xref: /freebsd/sys/netinet/tcp_subr.c (revision 1db64f89363c97858961c4df0b7d02f3223723cf)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 #include "opt_inet.h"
34 #include "opt_inet6.h"
35 #include "opt_ipsec.h"
36 #include "opt_kern_tls.h"
37 
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/arb.h>
41 #include <sys/callout.h>
42 #include <sys/eventhandler.h>
43 #ifdef TCP_HHOOK
44 #include <sys/hhook.h>
45 #endif
46 #include <sys/kernel.h>
47 #ifdef TCP_HHOOK
48 #include <sys/khelp.h>
49 #endif
50 #ifdef KERN_TLS
51 #include <sys/ktls.h>
52 #endif
53 #include <sys/qmath.h>
54 #include <sys/stats.h>
55 #include <sys/sysctl.h>
56 #include <sys/jail.h>
57 #include <sys/malloc.h>
58 #include <sys/refcount.h>
59 #include <sys/mbuf.h>
60 #include <sys/priv.h>
61 #include <sys/proc.h>
62 #include <sys/sdt.h>
63 #include <sys/socket.h>
64 #include <sys/socketvar.h>
65 #include <sys/protosw.h>
66 #include <sys/random.h>
67 
68 #include <vm/uma.h>
69 
70 #include <net/route.h>
71 #include <net/route/nhop.h>
72 #include <net/if.h>
73 #include <net/if_var.h>
74 #include <net/if_private.h>
75 #include <net/vnet.h>
76 
77 #include <netinet/in.h>
78 #include <netinet/in_fib.h>
79 #include <netinet/in_kdtrace.h>
80 #include <netinet/in_pcb.h>
81 #include <netinet/in_systm.h>
82 #include <netinet/in_var.h>
83 #include <netinet/ip.h>
84 #include <netinet/ip_icmp.h>
85 #include <netinet/ip_var.h>
86 #ifdef INET6
87 #include <netinet/icmp6.h>
88 #include <netinet/ip6.h>
89 #include <netinet6/in6_fib.h>
90 #include <netinet6/in6_pcb.h>
91 #include <netinet6/ip6_var.h>
92 #include <netinet6/scope6_var.h>
93 #include <netinet6/nd6.h>
94 #endif
95 
96 #include <netinet/tcp.h>
97 #ifdef INVARIANTS
98 #define TCPSTATES
99 #endif
100 #include <netinet/tcp_fsm.h>
101 #include <netinet/tcp_seq.h>
102 #include <netinet/tcp_timer.h>
103 #include <netinet/tcp_var.h>
104 #include <netinet/tcp_ecn.h>
105 #include <netinet/tcp_log_buf.h>
106 #include <netinet/tcp_syncache.h>
107 #include <netinet/tcp_hpts.h>
108 #include <netinet/tcp_lro.h>
109 #include <netinet/cc/cc.h>
110 #include <netinet/tcpip.h>
111 #include <netinet/tcp_fastopen.h>
112 #include <netinet/tcp_accounting.h>
113 #ifdef TCPPCAP
114 #include <netinet/tcp_pcap.h>
115 #endif
116 #ifdef TCP_OFFLOAD
117 #include <netinet/tcp_offload.h>
118 #endif
119 #include <netinet/udp.h>
120 #include <netinet/udp_var.h>
121 #ifdef INET6
122 #include <netinet6/tcp6_var.h>
123 #endif
124 
125 #include <netipsec/ipsec_support.h>
126 
127 #include <machine/in_cksum.h>
128 #include <crypto/siphash/siphash.h>
129 
130 #include <security/mac/mac_framework.h>
131 
132 #ifdef INET6
133 static ip6proto_ctlinput_t tcp6_ctlinput;
134 static udp_tun_icmp_t tcp6_ctlinput_viaudp;
135 #endif
136 
137 VNET_DEFINE(int, tcp_mssdflt) = TCP_MSS;
138 #ifdef INET6
139 VNET_DEFINE(int, tcp_v6mssdflt) = TCP6_MSS;
140 #endif
141 
142 #ifdef TCP_SAD_DETECTION
143 /*  Sack attack detection thresholds and such */
144 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, sack_attack,
145     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
146     "Sack Attack detection thresholds");
147 int32_t tcp_force_detection = 0;
148 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, force_detection,
149     CTLFLAG_RW,
150     &tcp_force_detection, 0,
151     "Do we force detection even if the INP has it off?");
152 int32_t tcp_sad_limit = 10000;
153 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, limit,
154     CTLFLAG_RW,
155     &tcp_sad_limit, 10000,
156     "If SaD is enabled, what is the limit to sendmap entries (0 = unlimited)?");
157 int32_t tcp_sack_to_ack_thresh = 700;	/* 70 % */
158 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, sack_to_ack_thresh,
159     CTLFLAG_RW,
160     &tcp_sack_to_ack_thresh, 700,
161     "Percentage of sacks to acks we must see above (10.1 percent is 101)?");
162 int32_t tcp_sack_to_move_thresh = 600;	/* 60 % */
163 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, move_thresh,
164     CTLFLAG_RW,
165     &tcp_sack_to_move_thresh, 600,
166     "Percentage of sack moves we must see above (10.1 percent is 101)");
167 int32_t tcp_restoral_thresh = 450;	/* 45 % (sack:2:ack -25%) (mv:ratio -15%) **/
168 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, restore_thresh,
169     CTLFLAG_RW,
170     &tcp_restoral_thresh, 450,
171     "Percentage of sack to ack percentage we must see below to restore(10.1 percent is 101)");
172 int32_t tcp_sad_decay_val = 800;
173 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, decay_per,
174     CTLFLAG_RW,
175     &tcp_sad_decay_val, 800,
176     "The decay percentage (10.1 percent equals 101 )");
177 int32_t tcp_map_minimum = 500;
178 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, nummaps,
179     CTLFLAG_RW,
180     &tcp_map_minimum, 500,
181     "Number of Map enteries before we start detection");
182 int32_t tcp_sad_pacing_interval = 2000;
183 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, sad_pacing_int,
184     CTLFLAG_RW,
185     &tcp_sad_pacing_interval, 2000,
186     "What is the minimum pacing interval for a classified attacker?");
187 
188 int32_t tcp_sad_low_pps = 100;
189 SYSCTL_INT(_net_inet_tcp_sack_attack, OID_AUTO, sad_low_pps,
190     CTLFLAG_RW,
191     &tcp_sad_low_pps, 100,
192     "What is the input pps that below which we do not decay?");
193 #endif
194 uint32_t tcp_ack_war_time_window = 1000;
195 SYSCTL_UINT(_net_inet_tcp, OID_AUTO, ack_war_timewindow,
196     CTLFLAG_RW,
197     &tcp_ack_war_time_window, 1000,
198    "If the tcp_stack does ack-war prevention how many milliseconds are in its time window?");
199 uint32_t tcp_ack_war_cnt = 5;
200 SYSCTL_UINT(_net_inet_tcp, OID_AUTO, ack_war_cnt,
201     CTLFLAG_RW,
202     &tcp_ack_war_cnt, 5,
203    "If the tcp_stack does ack-war prevention how many acks can be sent in its time window?");
204 
205 struct rwlock tcp_function_lock;
206 
207 static int
208 sysctl_net_inet_tcp_mss_check(SYSCTL_HANDLER_ARGS)
209 {
210 	int error, new;
211 
212 	new = V_tcp_mssdflt;
213 	error = sysctl_handle_int(oidp, &new, 0, req);
214 	if (error == 0 && req->newptr) {
215 		if (new < TCP_MINMSS)
216 			error = EINVAL;
217 		else
218 			V_tcp_mssdflt = new;
219 	}
220 	return (error);
221 }
222 
223 SYSCTL_PROC(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt,
224     CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
225     &VNET_NAME(tcp_mssdflt), 0, &sysctl_net_inet_tcp_mss_check, "I",
226     "Default TCP Maximum Segment Size");
227 
228 #ifdef INET6
229 static int
230 sysctl_net_inet_tcp_mss_v6_check(SYSCTL_HANDLER_ARGS)
231 {
232 	int error, new;
233 
234 	new = V_tcp_v6mssdflt;
235 	error = sysctl_handle_int(oidp, &new, 0, req);
236 	if (error == 0 && req->newptr) {
237 		if (new < TCP_MINMSS)
238 			error = EINVAL;
239 		else
240 			V_tcp_v6mssdflt = new;
241 	}
242 	return (error);
243 }
244 
245 SYSCTL_PROC(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
246     CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
247     &VNET_NAME(tcp_v6mssdflt), 0, &sysctl_net_inet_tcp_mss_v6_check, "I",
248    "Default TCP Maximum Segment Size for IPv6");
249 #endif /* INET6 */
250 
251 /*
252  * Minimum MSS we accept and use. This prevents DoS attacks where
253  * we are forced to a ridiculous low MSS like 20 and send hundreds
254  * of packets instead of one. The effect scales with the available
255  * bandwidth and quickly saturates the CPU and network interface
256  * with packet generation and sending. Set to zero to disable MINMSS
257  * checking. This setting prevents us from sending too small packets.
258  */
259 VNET_DEFINE(int, tcp_minmss) = TCP_MINMSS;
260 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_VNET | CTLFLAG_RW,
261      &VNET_NAME(tcp_minmss), 0,
262     "Minimum TCP Maximum Segment Size");
263 
264 VNET_DEFINE(int, tcp_do_rfc1323) = 1;
265 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_VNET | CTLFLAG_RW,
266     &VNET_NAME(tcp_do_rfc1323), 0,
267     "Enable rfc1323 (high performance TCP) extensions");
268 
269 /*
270  * As of June 2021, several TCP stacks violate RFC 7323 from September 2014.
271  * Some stacks negotiate TS, but never send them after connection setup. Some
272  * stacks negotiate TS, but don't send them when sending keep-alive segments.
273  * These include modern widely deployed TCP stacks.
274  * Therefore tolerating violations for now...
275  */
276 VNET_DEFINE(int, tcp_tolerate_missing_ts) = 1;
277 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tolerate_missing_ts, CTLFLAG_VNET | CTLFLAG_RW,
278     &VNET_NAME(tcp_tolerate_missing_ts), 0,
279     "Tolerate missing TCP timestamps");
280 
281 VNET_DEFINE(int, tcp_ts_offset_per_conn) = 1;
282 SYSCTL_INT(_net_inet_tcp, OID_AUTO, ts_offset_per_conn, CTLFLAG_VNET | CTLFLAG_RW,
283     &VNET_NAME(tcp_ts_offset_per_conn), 0,
284     "Initialize TCP timestamps per connection instead of per host pair");
285 
286 /* How many connections are pacing */
287 static volatile uint32_t number_of_tcp_connections_pacing = 0;
288 static uint32_t shadow_num_connections = 0;
289 static counter_u64_t tcp_pacing_failures;
290 
291 static int tcp_pacing_limit = 10000;
292 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pacing_limit, CTLFLAG_RW,
293     &tcp_pacing_limit, 1000,
294     "If the TCP stack does pacing, is there a limit (-1 = no, 0 = no pacing N = number of connections)");
295 
296 SYSCTL_UINT(_net_inet_tcp, OID_AUTO, pacing_count, CTLFLAG_RD,
297     &shadow_num_connections, 0, "Number of TCP connections being paced");
298 
299 SYSCTL_COUNTER_U64(_net_inet_tcp, OID_AUTO, pacing_failures, CTLFLAG_RD,
300     &tcp_pacing_failures, "Number of times we failed to enable pacing to avoid exceeding the limit");
301 
302 static int	tcp_log_debug = 0;
303 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW,
304     &tcp_log_debug, 0, "Log errors caused by incoming TCP segments");
305 
306 /*
307  * Target size of TCP PCB hash tables. Must be a power of two.
308  *
309  * Note that this can be overridden by the kernel environment
310  * variable net.inet.tcp.tcbhashsize
311  */
312 #ifndef TCBHASHSIZE
313 #define TCBHASHSIZE	0
314 #endif
315 static int	tcp_tcbhashsize = TCBHASHSIZE;
316 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN,
317     &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
318 
319 static int	do_tcpdrain = 1;
320 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
321     "Enable tcp_drain routine for extra help when low on mbufs");
322 
323 SYSCTL_UINT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_VNET | CTLFLAG_RD,
324     &VNET_NAME(tcbinfo.ipi_count), 0, "Number of active PCBs");
325 
326 VNET_DEFINE_STATIC(int, icmp_may_rst) = 1;
327 #define	V_icmp_may_rst			VNET(icmp_may_rst)
328 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_VNET | CTLFLAG_RW,
329     &VNET_NAME(icmp_may_rst), 0,
330     "Certain ICMP unreachable messages may abort connections in SYN_SENT");
331 
332 VNET_DEFINE_STATIC(int, tcp_isn_reseed_interval) = 0;
333 #define	V_tcp_isn_reseed_interval	VNET(tcp_isn_reseed_interval)
334 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_VNET | CTLFLAG_RW,
335     &VNET_NAME(tcp_isn_reseed_interval), 0,
336     "Seconds between reseeding of ISN secret");
337 
338 static int	tcp_soreceive_stream;
339 SYSCTL_INT(_net_inet_tcp, OID_AUTO, soreceive_stream, CTLFLAG_RDTUN,
340     &tcp_soreceive_stream, 0, "Using soreceive_stream for TCP sockets");
341 
342 VNET_DEFINE(uma_zone_t, sack_hole_zone);
343 #define	V_sack_hole_zone		VNET(sack_hole_zone)
344 VNET_DEFINE(uint32_t, tcp_map_entries_limit) = 0;	/* unlimited */
345 static int
346 sysctl_net_inet_tcp_map_limit_check(SYSCTL_HANDLER_ARGS)
347 {
348 	int error;
349 	uint32_t new;
350 
351 	new = V_tcp_map_entries_limit;
352 	error = sysctl_handle_int(oidp, &new, 0, req);
353 	if (error == 0 && req->newptr) {
354 		/* only allow "0" and value > minimum */
355 		if (new > 0 && new < TCP_MIN_MAP_ENTRIES_LIMIT)
356 			error = EINVAL;
357 		else
358 			V_tcp_map_entries_limit = new;
359 	}
360 	return (error);
361 }
362 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, map_limit,
363     CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
364     &VNET_NAME(tcp_map_entries_limit), 0,
365     &sysctl_net_inet_tcp_map_limit_check, "IU",
366     "Total sendmap entries limit");
367 
368 VNET_DEFINE(uint32_t, tcp_map_split_limit) = 0;	/* unlimited */
369 SYSCTL_UINT(_net_inet_tcp, OID_AUTO, split_limit, CTLFLAG_VNET | CTLFLAG_RW,
370      &VNET_NAME(tcp_map_split_limit), 0,
371     "Total sendmap split entries limit");
372 
373 #ifdef TCP_HHOOK
374 VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
375 #endif
376 
377 #define TS_OFFSET_SECRET_LENGTH SIPHASH_KEY_LENGTH
378 VNET_DEFINE_STATIC(u_char, ts_offset_secret[TS_OFFSET_SECRET_LENGTH]);
379 #define	V_ts_offset_secret	VNET(ts_offset_secret)
380 
381 static int	tcp_default_fb_init(struct tcpcb *tp, void **ptr);
382 static void	tcp_default_fb_fini(struct tcpcb *tp, int tcb_is_purged);
383 static int	tcp_default_handoff_ok(struct tcpcb *tp);
384 static struct inpcb *tcp_notify(struct inpcb *, int);
385 static struct inpcb *tcp_mtudisc_notify(struct inpcb *, int);
386 static struct inpcb *tcp_mtudisc(struct inpcb *, int);
387 static struct inpcb *tcp_drop_syn_sent(struct inpcb *, int);
388 static char *	tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
389 		    const void *ip4hdr, const void *ip6hdr);
390 static void	tcp_default_switch_failed(struct tcpcb *tp);
391 static ipproto_ctlinput_t	tcp_ctlinput;
392 static udp_tun_icmp_t		tcp_ctlinput_viaudp;
393 
394 static struct tcp_function_block tcp_def_funcblk = {
395 	.tfb_tcp_block_name = "freebsd",
396 	.tfb_tcp_output = tcp_default_output,
397 	.tfb_tcp_do_segment = tcp_do_segment,
398 	.tfb_tcp_ctloutput = tcp_default_ctloutput,
399 	.tfb_tcp_handoff_ok = tcp_default_handoff_ok,
400 	.tfb_tcp_fb_init = tcp_default_fb_init,
401 	.tfb_tcp_fb_fini = tcp_default_fb_fini,
402 	.tfb_switch_failed = tcp_default_switch_failed,
403 };
404 
405 static int tcp_fb_cnt = 0;
406 struct tcp_funchead t_functions;
407 VNET_DEFINE_STATIC(struct tcp_function_block *, tcp_func_set_ptr) = &tcp_def_funcblk;
408 #define	V_tcp_func_set_ptr VNET(tcp_func_set_ptr)
409 
410 void
411 tcp_record_dsack(struct tcpcb *tp, tcp_seq start, tcp_seq end, int tlp)
412 {
413 	TCPSTAT_INC(tcps_dsack_count);
414 	tp->t_dsack_pack++;
415 	if (tlp == 0) {
416 		if (SEQ_GT(end, start)) {
417 			tp->t_dsack_bytes += (end - start);
418 			TCPSTAT_ADD(tcps_dsack_bytes, (end - start));
419 		} else {
420 			tp->t_dsack_tlp_bytes += (start - end);
421 			TCPSTAT_ADD(tcps_dsack_bytes, (start - end));
422 		}
423 	} else {
424 		if (SEQ_GT(end, start)) {
425 			tp->t_dsack_bytes += (end - start);
426 			TCPSTAT_ADD(tcps_dsack_tlp_bytes, (end - start));
427 		} else {
428 			tp->t_dsack_tlp_bytes += (start - end);
429 			TCPSTAT_ADD(tcps_dsack_tlp_bytes, (start - end));
430 		}
431 	}
432 }
433 
434 static struct tcp_function_block *
435 find_tcp_functions_locked(struct tcp_function_set *fs)
436 {
437 	struct tcp_function *f;
438 	struct tcp_function_block *blk=NULL;
439 
440 	TAILQ_FOREACH(f, &t_functions, tf_next) {
441 		if (strcmp(f->tf_name, fs->function_set_name) == 0) {
442 			blk = f->tf_fb;
443 			break;
444 		}
445 	}
446 	return(blk);
447 }
448 
449 static struct tcp_function_block *
450 find_tcp_fb_locked(struct tcp_function_block *blk, struct tcp_function **s)
451 {
452 	struct tcp_function_block *rblk=NULL;
453 	struct tcp_function *f;
454 
455 	TAILQ_FOREACH(f, &t_functions, tf_next) {
456 		if (f->tf_fb == blk) {
457 			rblk = blk;
458 			if (s) {
459 				*s = f;
460 			}
461 			break;
462 		}
463 	}
464 	return (rblk);
465 }
466 
467 struct tcp_function_block *
468 find_and_ref_tcp_functions(struct tcp_function_set *fs)
469 {
470 	struct tcp_function_block *blk;
471 
472 	rw_rlock(&tcp_function_lock);
473 	blk = find_tcp_functions_locked(fs);
474 	if (blk)
475 		refcount_acquire(&blk->tfb_refcnt);
476 	rw_runlock(&tcp_function_lock);
477 	return(blk);
478 }
479 
480 struct tcp_function_block *
481 find_and_ref_tcp_fb(struct tcp_function_block *blk)
482 {
483 	struct tcp_function_block *rblk;
484 
485 	rw_rlock(&tcp_function_lock);
486 	rblk = find_tcp_fb_locked(blk, NULL);
487 	if (rblk)
488 		refcount_acquire(&rblk->tfb_refcnt);
489 	rw_runlock(&tcp_function_lock);
490 	return(rblk);
491 }
492 
493 /* Find a matching alias for the given tcp_function_block. */
494 int
495 find_tcp_function_alias(struct tcp_function_block *blk,
496     struct tcp_function_set *fs)
497 {
498 	struct tcp_function *f;
499 	int found;
500 
501 	found = 0;
502 	rw_rlock(&tcp_function_lock);
503 	TAILQ_FOREACH(f, &t_functions, tf_next) {
504 		if ((f->tf_fb == blk) &&
505 		    (strncmp(f->tf_name, blk->tfb_tcp_block_name,
506 		        TCP_FUNCTION_NAME_LEN_MAX) != 0)) {
507 			/* Matching function block with different name. */
508 			strncpy(fs->function_set_name, f->tf_name,
509 			    TCP_FUNCTION_NAME_LEN_MAX);
510 			found = 1;
511 			break;
512 		}
513 	}
514 	/* Null terminate the string appropriately. */
515 	if (found) {
516 		fs->function_set_name[TCP_FUNCTION_NAME_LEN_MAX - 1] = '\0';
517 	} else {
518 		fs->function_set_name[0] = '\0';
519 	}
520 	rw_runlock(&tcp_function_lock);
521 	return (found);
522 }
523 
524 static struct tcp_function_block *
525 find_and_ref_tcp_default_fb(void)
526 {
527 	struct tcp_function_block *rblk;
528 
529 	rw_rlock(&tcp_function_lock);
530 	rblk = V_tcp_func_set_ptr;
531 	refcount_acquire(&rblk->tfb_refcnt);
532 	rw_runlock(&tcp_function_lock);
533 	return (rblk);
534 }
535 
536 void
537 tcp_switch_back_to_default(struct tcpcb *tp)
538 {
539 	struct tcp_function_block *tfb;
540 	void *ptr = NULL;
541 
542 	KASSERT(tp->t_fb != &tcp_def_funcblk,
543 	    ("%s: called by the built-in default stack", __func__));
544 
545 	/*
546 	 * Now, we'll find a new function block to use.
547 	 * Start by trying the current user-selected
548 	 * default, unless this stack is the user-selected
549 	 * default.
550 	 */
551 	tfb = find_and_ref_tcp_default_fb();
552 	if (tfb == tp->t_fb) {
553 		refcount_release(&tfb->tfb_refcnt);
554 		tfb = NULL;
555 	}
556 	/* Does the stack accept this connection? */
557 	if (tfb != NULL && tfb->tfb_tcp_handoff_ok != NULL &&
558 	    (*tfb->tfb_tcp_handoff_ok)(tp)) {
559 		refcount_release(&tfb->tfb_refcnt);
560 		tfb = NULL;
561 	}
562 	/* Try to use that stack. */
563 	if (tfb != NULL) {
564 		/* Initialize the new stack. If it succeeds, we are done. */
565 		if (tfb->tfb_tcp_fb_init == NULL ||
566 		    (*tfb->tfb_tcp_fb_init)(tp, &ptr) == 0) {
567 			/* Release the old stack */
568 			if (tp->t_fb->tfb_tcp_fb_fini != NULL)
569 				(*tp->t_fb->tfb_tcp_fb_fini)(tp, 0);
570 			refcount_release(&tp->t_fb->tfb_refcnt);
571 			/* Now set in all the pointers */
572 			tp->t_fb = tfb;
573 			tp->t_fb_ptr = ptr;
574 			return;
575 		}
576 		/*
577 		 * Initialization failed. Release the reference count on
578 		 * the looked up default stack.
579 		 */
580 		refcount_release(&tfb->tfb_refcnt);
581 	}
582 
583 	/*
584 	 * If that wasn't feasible, use the built-in default
585 	 * stack which is not allowed to reject anyone.
586 	 */
587 	tfb = find_and_ref_tcp_fb(&tcp_def_funcblk);
588 	if (tfb == NULL) {
589 		/* there always should be a default */
590 		panic("Can't refer to tcp_def_funcblk");
591 	}
592 	if (tfb->tfb_tcp_handoff_ok != NULL) {
593 		if ((*tfb->tfb_tcp_handoff_ok) (tp)) {
594 			/* The default stack cannot say no */
595 			panic("Default stack rejects a new session?");
596 		}
597 	}
598 	if (tfb->tfb_tcp_fb_init != NULL &&
599 	    (*tfb->tfb_tcp_fb_init)(tp, &ptr)) {
600 		/* The default stack cannot fail */
601 		panic("Default stack initialization failed");
602 	}
603 	/* Now release the old stack */
604 	if (tp->t_fb->tfb_tcp_fb_fini != NULL)
605 		(*tp->t_fb->tfb_tcp_fb_fini)(tp, 0);
606 	refcount_release(&tp->t_fb->tfb_refcnt);
607 	/* And set in the pointers to the new */
608 	tp->t_fb = tfb;
609 	tp->t_fb_ptr = ptr;
610 }
611 
612 static bool
613 tcp_recv_udp_tunneled_packet(struct mbuf *m, int off, struct inpcb *inp,
614     const struct sockaddr *sa, void *ctx)
615 {
616 	struct ip *iph;
617 #ifdef INET6
618 	struct ip6_hdr *ip6;
619 #endif
620 	struct udphdr *uh;
621 	struct tcphdr *th;
622 	int thlen;
623 	uint16_t port;
624 
625 	TCPSTAT_INC(tcps_tunneled_pkts);
626 	if ((m->m_flags & M_PKTHDR) == 0) {
627 		/* Can't handle one that is not a pkt hdr */
628 		TCPSTAT_INC(tcps_tunneled_errs);
629 		goto out;
630 	}
631 	thlen = sizeof(struct tcphdr);
632 	if (m->m_len < off + sizeof(struct udphdr) + thlen &&
633 	    (m =  m_pullup(m, off + sizeof(struct udphdr) + thlen)) == NULL) {
634 		TCPSTAT_INC(tcps_tunneled_errs);
635 		goto out;
636 	}
637 	iph = mtod(m, struct ip *);
638 	uh = (struct udphdr *)((caddr_t)iph + off);
639 	th = (struct tcphdr *)(uh + 1);
640 	thlen = th->th_off << 2;
641 	if (m->m_len < off + sizeof(struct udphdr) + thlen) {
642 		m =  m_pullup(m, off + sizeof(struct udphdr) + thlen);
643 		if (m == NULL) {
644 			TCPSTAT_INC(tcps_tunneled_errs);
645 			goto out;
646 		} else {
647 			iph = mtod(m, struct ip *);
648 			uh = (struct udphdr *)((caddr_t)iph + off);
649 			th = (struct tcphdr *)(uh + 1);
650 		}
651 	}
652 	m->m_pkthdr.tcp_tun_port = port = uh->uh_sport;
653 	bcopy(th, uh, m->m_len - off);
654 	m->m_len -= sizeof(struct udphdr);
655 	m->m_pkthdr.len -= sizeof(struct udphdr);
656 	/*
657 	 * We use the same algorithm for
658 	 * both UDP and TCP for c-sum. So
659 	 * the code in tcp_input will skip
660 	 * the checksum. So we do nothing
661 	 * with the flag (m->m_pkthdr.csum_flags).
662 	 */
663 	switch (iph->ip_v) {
664 #ifdef INET
665 	case IPVERSION:
666 		iph->ip_len = htons(ntohs(iph->ip_len) - sizeof(struct udphdr));
667 		tcp_input_with_port(&m, &off, IPPROTO_TCP, port);
668 		break;
669 #endif
670 #ifdef INET6
671 	case IPV6_VERSION >> 4:
672 		ip6 = mtod(m, struct ip6_hdr *);
673 		ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - sizeof(struct udphdr));
674 		tcp6_input_with_port(&m, &off, IPPROTO_TCP, port);
675 		break;
676 #endif
677 	default:
678 		goto out;
679 		break;
680 	}
681 	return (true);
682 out:
683 	m_freem(m);
684 
685 	return (true);
686 }
687 
688 static int
689 sysctl_net_inet_default_tcp_functions(SYSCTL_HANDLER_ARGS)
690 {
691 	int error=ENOENT;
692 	struct tcp_function_set fs;
693 	struct tcp_function_block *blk;
694 
695 	memset(&fs, 0, sizeof(fs));
696 	rw_rlock(&tcp_function_lock);
697 	blk = find_tcp_fb_locked(V_tcp_func_set_ptr, NULL);
698 	if (blk) {
699 		/* Found him */
700 		strcpy(fs.function_set_name, blk->tfb_tcp_block_name);
701 		fs.pcbcnt = blk->tfb_refcnt;
702 	}
703 	rw_runlock(&tcp_function_lock);
704 	error = sysctl_handle_string(oidp, fs.function_set_name,
705 				     sizeof(fs.function_set_name), req);
706 
707 	/* Check for error or no change */
708 	if (error != 0 || req->newptr == NULL)
709 		return(error);
710 
711 	rw_wlock(&tcp_function_lock);
712 	blk = find_tcp_functions_locked(&fs);
713 	if ((blk == NULL) ||
714 	    (blk->tfb_flags & TCP_FUNC_BEING_REMOVED)) {
715 		error = ENOENT;
716 		goto done;
717 	}
718 	V_tcp_func_set_ptr = blk;
719 done:
720 	rw_wunlock(&tcp_function_lock);
721 	return (error);
722 }
723 
724 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, functions_default,
725     CTLFLAG_VNET | CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
726     NULL, 0, sysctl_net_inet_default_tcp_functions, "A",
727     "Set/get the default TCP functions");
728 
729 static int
730 sysctl_net_inet_list_available(SYSCTL_HANDLER_ARGS)
731 {
732 	int error, cnt, linesz;
733 	struct tcp_function *f;
734 	char *buffer, *cp;
735 	size_t bufsz, outsz;
736 	bool alias;
737 
738 	cnt = 0;
739 	rw_rlock(&tcp_function_lock);
740 	TAILQ_FOREACH(f, &t_functions, tf_next) {
741 		cnt++;
742 	}
743 	rw_runlock(&tcp_function_lock);
744 
745 	bufsz = (cnt+2) * ((TCP_FUNCTION_NAME_LEN_MAX * 2) + 13) + 1;
746 	buffer = malloc(bufsz, M_TEMP, M_WAITOK);
747 
748 	error = 0;
749 	cp = buffer;
750 
751 	linesz = snprintf(cp, bufsz, "\n%-32s%c %-32s %s\n", "Stack", 'D',
752 	    "Alias", "PCB count");
753 	cp += linesz;
754 	bufsz -= linesz;
755 	outsz = linesz;
756 
757 	rw_rlock(&tcp_function_lock);
758 	TAILQ_FOREACH(f, &t_functions, tf_next) {
759 		alias = (f->tf_name != f->tf_fb->tfb_tcp_block_name);
760 		linesz = snprintf(cp, bufsz, "%-32s%c %-32s %u\n",
761 		    f->tf_fb->tfb_tcp_block_name,
762 		    (f->tf_fb == V_tcp_func_set_ptr) ? '*' : ' ',
763 		    alias ? f->tf_name : "-",
764 		    f->tf_fb->tfb_refcnt);
765 		if (linesz >= bufsz) {
766 			error = EOVERFLOW;
767 			break;
768 		}
769 		cp += linesz;
770 		bufsz -= linesz;
771 		outsz += linesz;
772 	}
773 	rw_runlock(&tcp_function_lock);
774 	if (error == 0)
775 		error = sysctl_handle_string(oidp, buffer, outsz + 1, req);
776 	free(buffer, M_TEMP);
777 	return (error);
778 }
779 
780 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, functions_available,
781     CTLFLAG_VNET | CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT,
782     NULL, 0, sysctl_net_inet_list_available, "A",
783     "list available TCP Function sets");
784 
785 VNET_DEFINE(int, tcp_udp_tunneling_port) = TCP_TUNNELING_PORT_DEFAULT;
786 
787 #ifdef INET
788 VNET_DEFINE(struct socket *, udp4_tun_socket) = NULL;
789 #define	V_udp4_tun_socket	VNET(udp4_tun_socket)
790 #endif
791 #ifdef INET6
792 VNET_DEFINE(struct socket *, udp6_tun_socket) = NULL;
793 #define	V_udp6_tun_socket	VNET(udp6_tun_socket)
794 #endif
795 
796 static struct sx tcpoudp_lock;
797 
798 static void
799 tcp_over_udp_stop(void)
800 {
801 
802 	sx_assert(&tcpoudp_lock, SA_XLOCKED);
803 
804 #ifdef INET
805 	if (V_udp4_tun_socket != NULL) {
806 		soclose(V_udp4_tun_socket);
807 		V_udp4_tun_socket = NULL;
808 	}
809 #endif
810 #ifdef INET6
811 	if (V_udp6_tun_socket != NULL) {
812 		soclose(V_udp6_tun_socket);
813 		V_udp6_tun_socket = NULL;
814 	}
815 #endif
816 }
817 
818 static int
819 tcp_over_udp_start(void)
820 {
821 	uint16_t port;
822 	int ret;
823 #ifdef INET
824 	struct sockaddr_in sin;
825 #endif
826 #ifdef INET6
827 	struct sockaddr_in6 sin6;
828 #endif
829 
830 	sx_assert(&tcpoudp_lock, SA_XLOCKED);
831 
832 	port = V_tcp_udp_tunneling_port;
833 	if (ntohs(port) == 0) {
834 		/* Must have a port set */
835 		return (EINVAL);
836 	}
837 #ifdef INET
838 	if (V_udp4_tun_socket != NULL) {
839 		/* Already running -- must stop first */
840 		return (EALREADY);
841 	}
842 #endif
843 #ifdef INET6
844 	if (V_udp6_tun_socket != NULL) {
845 		/* Already running -- must stop first */
846 		return (EALREADY);
847 	}
848 #endif
849 #ifdef INET
850 	if ((ret = socreate(PF_INET, &V_udp4_tun_socket,
851 	    SOCK_DGRAM, IPPROTO_UDP,
852 	    curthread->td_ucred, curthread))) {
853 		tcp_over_udp_stop();
854 		return (ret);
855 	}
856 	/* Call the special UDP hook. */
857 	if ((ret = udp_set_kernel_tunneling(V_udp4_tun_socket,
858 	    tcp_recv_udp_tunneled_packet,
859 	    tcp_ctlinput_viaudp,
860 	    NULL))) {
861 		tcp_over_udp_stop();
862 		return (ret);
863 	}
864 	/* Ok, we have a socket, bind it to the port. */
865 	memset(&sin, 0, sizeof(struct sockaddr_in));
866 	sin.sin_len = sizeof(struct sockaddr_in);
867 	sin.sin_family = AF_INET;
868 	sin.sin_port = htons(port);
869 	if ((ret = sobind(V_udp4_tun_socket,
870 	    (struct sockaddr *)&sin, curthread))) {
871 		tcp_over_udp_stop();
872 		return (ret);
873 	}
874 #endif
875 #ifdef INET6
876 	if ((ret = socreate(PF_INET6, &V_udp6_tun_socket,
877 	    SOCK_DGRAM, IPPROTO_UDP,
878 	    curthread->td_ucred, curthread))) {
879 		tcp_over_udp_stop();
880 		return (ret);
881 	}
882 	/* Call the special UDP hook. */
883 	if ((ret = udp_set_kernel_tunneling(V_udp6_tun_socket,
884 	    tcp_recv_udp_tunneled_packet,
885 	    tcp6_ctlinput_viaudp,
886 	    NULL))) {
887 		tcp_over_udp_stop();
888 		return (ret);
889 	}
890 	/* Ok, we have a socket, bind it to the port. */
891 	memset(&sin6, 0, sizeof(struct sockaddr_in6));
892 	sin6.sin6_len = sizeof(struct sockaddr_in6);
893 	sin6.sin6_family = AF_INET6;
894 	sin6.sin6_port = htons(port);
895 	if ((ret = sobind(V_udp6_tun_socket,
896 	    (struct sockaddr *)&sin6, curthread))) {
897 		tcp_over_udp_stop();
898 		return (ret);
899 	}
900 #endif
901 	return (0);
902 }
903 
904 static int
905 sysctl_net_inet_tcp_udp_tunneling_port_check(SYSCTL_HANDLER_ARGS)
906 {
907 	int error;
908 	uint32_t old, new;
909 
910 	old = V_tcp_udp_tunneling_port;
911 	new = old;
912 	error = sysctl_handle_int(oidp, &new, 0, req);
913 	if ((error == 0) &&
914 	    (req->newptr != NULL)) {
915 		if ((new < TCP_TUNNELING_PORT_MIN) ||
916 		    (new > TCP_TUNNELING_PORT_MAX)) {
917 			error = EINVAL;
918 		} else {
919 			sx_xlock(&tcpoudp_lock);
920 			V_tcp_udp_tunneling_port = new;
921 			if (old != 0) {
922 				tcp_over_udp_stop();
923 			}
924 			if (new != 0) {
925 				error = tcp_over_udp_start();
926 				if (error != 0) {
927 					V_tcp_udp_tunneling_port = 0;
928 				}
929 			}
930 			sx_xunlock(&tcpoudp_lock);
931 		}
932 	}
933 	return (error);
934 }
935 
936 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, udp_tunneling_port,
937     CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
938     &VNET_NAME(tcp_udp_tunneling_port),
939     0, &sysctl_net_inet_tcp_udp_tunneling_port_check, "IU",
940     "Tunneling port for tcp over udp");
941 
942 VNET_DEFINE(int, tcp_udp_tunneling_overhead) = TCP_TUNNELING_OVERHEAD_DEFAULT;
943 
944 static int
945 sysctl_net_inet_tcp_udp_tunneling_overhead_check(SYSCTL_HANDLER_ARGS)
946 {
947 	int error, new;
948 
949 	new = V_tcp_udp_tunneling_overhead;
950 	error = sysctl_handle_int(oidp, &new, 0, req);
951 	if (error == 0 && req->newptr) {
952 		if ((new < TCP_TUNNELING_OVERHEAD_MIN) ||
953 		    (new > TCP_TUNNELING_OVERHEAD_MAX))
954 			error = EINVAL;
955 		else
956 			V_tcp_udp_tunneling_overhead = new;
957 	}
958 	return (error);
959 }
960 
961 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, udp_tunneling_overhead,
962     CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
963     &VNET_NAME(tcp_udp_tunneling_overhead),
964     0, &sysctl_net_inet_tcp_udp_tunneling_overhead_check, "IU",
965     "MSS reduction when using tcp over udp");
966 
967 /*
968  * Exports one (struct tcp_function_info) for each alias/name.
969  */
970 static int
971 sysctl_net_inet_list_func_info(SYSCTL_HANDLER_ARGS)
972 {
973 	int cnt, error;
974 	struct tcp_function *f;
975 	struct tcp_function_info tfi;
976 
977 	/*
978 	 * We don't allow writes.
979 	 */
980 	if (req->newptr != NULL)
981 		return (EINVAL);
982 
983 	/*
984 	 * Wire the old buffer so we can directly copy the functions to
985 	 * user space without dropping the lock.
986 	 */
987 	if (req->oldptr != NULL) {
988 		error = sysctl_wire_old_buffer(req, 0);
989 		if (error)
990 			return (error);
991 	}
992 
993 	/*
994 	 * Walk the list and copy out matching entries. If INVARIANTS
995 	 * is compiled in, also walk the list to verify the length of
996 	 * the list matches what we have recorded.
997 	 */
998 	rw_rlock(&tcp_function_lock);
999 
1000 	cnt = 0;
1001 #ifndef INVARIANTS
1002 	if (req->oldptr == NULL) {
1003 		cnt = tcp_fb_cnt;
1004 		goto skip_loop;
1005 	}
1006 #endif
1007 	TAILQ_FOREACH(f, &t_functions, tf_next) {
1008 #ifdef INVARIANTS
1009 		cnt++;
1010 #endif
1011 		if (req->oldptr != NULL) {
1012 			bzero(&tfi, sizeof(tfi));
1013 			tfi.tfi_refcnt = f->tf_fb->tfb_refcnt;
1014 			tfi.tfi_id = f->tf_fb->tfb_id;
1015 			(void)strlcpy(tfi.tfi_alias, f->tf_name,
1016 			    sizeof(tfi.tfi_alias));
1017 			(void)strlcpy(tfi.tfi_name,
1018 			    f->tf_fb->tfb_tcp_block_name, sizeof(tfi.tfi_name));
1019 			error = SYSCTL_OUT(req, &tfi, sizeof(tfi));
1020 			/*
1021 			 * Don't stop on error, as that is the
1022 			 * mechanism we use to accumulate length
1023 			 * information if the buffer was too short.
1024 			 */
1025 		}
1026 	}
1027 	KASSERT(cnt == tcp_fb_cnt,
1028 	    ("%s: cnt (%d) != tcp_fb_cnt (%d)", __func__, cnt, tcp_fb_cnt));
1029 #ifndef INVARIANTS
1030 skip_loop:
1031 #endif
1032 	rw_runlock(&tcp_function_lock);
1033 	if (req->oldptr == NULL)
1034 		error = SYSCTL_OUT(req, NULL,
1035 		    (cnt + 1) * sizeof(struct tcp_function_info));
1036 
1037 	return (error);
1038 }
1039 
1040 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, function_info,
1041 	    CTLTYPE_OPAQUE | CTLFLAG_SKIP | CTLFLAG_RD | CTLFLAG_MPSAFE,
1042 	    NULL, 0, sysctl_net_inet_list_func_info, "S,tcp_function_info",
1043 	    "List TCP function block name-to-ID mappings");
1044 
1045 /*
1046  * tfb_tcp_handoff_ok() function for the default stack.
1047  * Note that we'll basically try to take all comers.
1048  */
1049 static int
1050 tcp_default_handoff_ok(struct tcpcb *tp)
1051 {
1052 
1053 	return (0);
1054 }
1055 
1056 /*
1057  * tfb_tcp_fb_init() function for the default stack.
1058  *
1059  * This handles making sure we have appropriate timers set if you are
1060  * transitioning a socket that has some amount of setup done.
1061  *
1062  * The init() fuction from the default can *never* return non-zero i.e.
1063  * it is required to always succeed since it is the stack of last resort!
1064  */
1065 static int
1066 tcp_default_fb_init(struct tcpcb *tp, void **ptr)
1067 {
1068 	struct socket *so = tptosocket(tp);
1069 	int rexmt;
1070 
1071 	INP_WLOCK_ASSERT(tptoinpcb(tp));
1072 	/* We don't use the pointer */
1073 	*ptr = NULL;
1074 
1075 	KASSERT(tp->t_state >= 0 && tp->t_state < TCPS_TIME_WAIT,
1076 	    ("%s: connection %p in unexpected state %d", __func__, tp,
1077 	    tp->t_state));
1078 
1079 	/* Make sure we get no interesting mbuf queuing behavior */
1080 	/* All mbuf queue/ack compress flags should be off */
1081 	tcp_lro_features_off(tp);
1082 
1083 	/* Cancel the GP measurement in progress */
1084 	tp->t_flags &= ~TF_GPUTINPROG;
1085 	/* Validate the timers are not in usec, if they are convert */
1086 	tcp_change_time_units(tp, TCP_TMR_GRANULARITY_TICKS);
1087 	if ((tp->t_state == TCPS_SYN_SENT) ||
1088 	    (tp->t_state == TCPS_SYN_RECEIVED))
1089 		rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
1090 	else
1091 		rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
1092 	if (tp->t_rxtshift == 0)
1093 		tp->t_rxtcur = rexmt;
1094 	else
1095 		TCPT_RANGESET(tp->t_rxtcur, rexmt, tp->t_rttmin, TCPTV_REXMTMAX);
1096 
1097 	/*
1098 	 * Nothing to do for ESTABLISHED or LISTEN states. And, we don't
1099 	 * know what to do for unexpected states (which includes TIME_WAIT).
1100 	 */
1101 	if (tp->t_state <= TCPS_LISTEN || tp->t_state >= TCPS_TIME_WAIT)
1102 		return (0);
1103 
1104 	/*
1105 	 * Make sure some kind of transmission timer is set if there is
1106 	 * outstanding data.
1107 	 */
1108 	if ((!TCPS_HAVEESTABLISHED(tp->t_state) || sbavail(&so->so_snd) ||
1109 	    tp->snd_una != tp->snd_max) && !(tcp_timer_active(tp, TT_REXMT) ||
1110 	    tcp_timer_active(tp, TT_PERSIST))) {
1111 		/*
1112 		 * If the session has established and it looks like it should
1113 		 * be in the persist state, set the persist timer. Otherwise,
1114 		 * set the retransmit timer.
1115 		 */
1116 		if (TCPS_HAVEESTABLISHED(tp->t_state) && tp->snd_wnd == 0 &&
1117 		    (int32_t)(tp->snd_nxt - tp->snd_una) <
1118 		    (int32_t)sbavail(&so->so_snd))
1119 			tcp_setpersist(tp);
1120 		else
1121 			tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp));
1122 	}
1123 
1124 	/* All non-embryonic sessions get a keepalive timer. */
1125 	if (!tcp_timer_active(tp, TT_KEEP))
1126 		tcp_timer_activate(tp, TT_KEEP,
1127 		    TCPS_HAVEESTABLISHED(tp->t_state) ? TP_KEEPIDLE(tp) :
1128 		    TP_KEEPINIT(tp));
1129 
1130 	/*
1131 	 * Make sure critical variables are initialized
1132 	 * if transitioning while in Recovery.
1133 	 */
1134 	if IN_FASTRECOVERY(tp->t_flags) {
1135 		if (tp->sackhint.recover_fs == 0)
1136 			tp->sackhint.recover_fs = max(1,
1137 			    tp->snd_nxt - tp->snd_una);
1138 	}
1139 
1140 	return (0);
1141 }
1142 
1143 /*
1144  * tfb_tcp_fb_fini() function for the default stack.
1145  *
1146  * This changes state as necessary (or prudent) to prepare for another stack
1147  * to assume responsibility for the connection.
1148  */
1149 static void
1150 tcp_default_fb_fini(struct tcpcb *tp, int tcb_is_purged)
1151 {
1152 
1153 	INP_WLOCK_ASSERT(tptoinpcb(tp));
1154 
1155 #ifdef TCP_BLACKBOX
1156 	tcp_log_flowend(tp);
1157 #endif
1158 	tp->t_acktime = 0;
1159 	return;
1160 }
1161 
1162 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers");
1163 MALLOC_DEFINE(M_TCPFUNCTIONS, "tcpfunc", "TCP function set memory");
1164 
1165 static struct mtx isn_mtx;
1166 
1167 #define	ISN_LOCK_INIT()	mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF)
1168 #define	ISN_LOCK()	mtx_lock(&isn_mtx)
1169 #define	ISN_UNLOCK()	mtx_unlock(&isn_mtx)
1170 
1171 INPCBSTORAGE_DEFINE(tcpcbstor, tcpcb, "tcpinp", "tcp_inpcb", "tcp", "tcphash");
1172 
1173 /*
1174  * Take a value and get the next power of 2 that doesn't overflow.
1175  * Used to size the tcp_inpcb hash buckets.
1176  */
1177 static int
1178 maketcp_hashsize(int size)
1179 {
1180 	int hashsize;
1181 
1182 	/*
1183 	 * auto tune.
1184 	 * get the next power of 2 higher than maxsockets.
1185 	 */
1186 	hashsize = 1 << fls(size);
1187 	/* catch overflow, and just go one power of 2 smaller */
1188 	if (hashsize < size) {
1189 		hashsize = 1 << (fls(size) - 1);
1190 	}
1191 	return (hashsize);
1192 }
1193 
1194 static volatile int next_tcp_stack_id = 1;
1195 
1196 /*
1197  * Register a TCP function block with the name provided in the names
1198  * array.  (Note that this function does NOT automatically register
1199  * blk->tfb_tcp_block_name as a stack name.  Therefore, you should
1200  * explicitly include blk->tfb_tcp_block_name in the list of names if
1201  * you wish to register the stack with that name.)
1202  *
1203  * Either all name registrations will succeed or all will fail.  If
1204  * a name registration fails, the function will update the num_names
1205  * argument to point to the array index of the name that encountered
1206  * the failure.
1207  *
1208  * Returns 0 on success, or an error code on failure.
1209  */
1210 int
1211 register_tcp_functions_as_names(struct tcp_function_block *blk, int wait,
1212     const char *names[], int *num_names)
1213 {
1214 	struct tcp_function *n;
1215 	struct tcp_function_set fs;
1216 	int error, i;
1217 
1218 	KASSERT(names != NULL && *num_names > 0,
1219 	    ("%s: Called with 0-length name list", __func__));
1220 	KASSERT(names != NULL, ("%s: Called with NULL name list", __func__));
1221 	KASSERT(rw_initialized(&tcp_function_lock),
1222 	    ("%s: called too early", __func__));
1223 
1224 	if ((blk->tfb_tcp_output == NULL) ||
1225 	    (blk->tfb_tcp_do_segment == NULL) ||
1226 	    (blk->tfb_tcp_ctloutput == NULL) ||
1227 	    (strlen(blk->tfb_tcp_block_name) == 0)) {
1228 		/*
1229 		 * These functions are required and you
1230 		 * need a name.
1231 		 */
1232 		*num_names = 0;
1233 		return (EINVAL);
1234 	}
1235 
1236 	if (blk->tfb_flags & TCP_FUNC_BEING_REMOVED) {
1237 		*num_names = 0;
1238 		return (EINVAL);
1239 	}
1240 
1241 	refcount_init(&blk->tfb_refcnt, 0);
1242 	blk->tfb_id = atomic_fetchadd_int(&next_tcp_stack_id, 1);
1243 	for (i = 0; i < *num_names; i++) {
1244 		n = malloc(sizeof(struct tcp_function), M_TCPFUNCTIONS, wait);
1245 		if (n == NULL) {
1246 			error = ENOMEM;
1247 			goto cleanup;
1248 		}
1249 		n->tf_fb = blk;
1250 
1251 		(void)strlcpy(fs.function_set_name, names[i],
1252 		    sizeof(fs.function_set_name));
1253 		rw_wlock(&tcp_function_lock);
1254 		if (find_tcp_functions_locked(&fs) != NULL) {
1255 			/* Duplicate name space not allowed */
1256 			rw_wunlock(&tcp_function_lock);
1257 			free(n, M_TCPFUNCTIONS);
1258 			error = EALREADY;
1259 			goto cleanup;
1260 		}
1261 		(void)strlcpy(n->tf_name, names[i], sizeof(n->tf_name));
1262 		TAILQ_INSERT_TAIL(&t_functions, n, tf_next);
1263 		tcp_fb_cnt++;
1264 		rw_wunlock(&tcp_function_lock);
1265 	}
1266 	return(0);
1267 
1268 cleanup:
1269 	/*
1270 	 * Deregister the names we just added. Because registration failed
1271 	 * for names[i], we don't need to deregister that name.
1272 	 */
1273 	*num_names = i;
1274 	rw_wlock(&tcp_function_lock);
1275 	while (--i >= 0) {
1276 		TAILQ_FOREACH(n, &t_functions, tf_next) {
1277 			if (!strncmp(n->tf_name, names[i],
1278 			    TCP_FUNCTION_NAME_LEN_MAX)) {
1279 				TAILQ_REMOVE(&t_functions, n, tf_next);
1280 				tcp_fb_cnt--;
1281 				n->tf_fb = NULL;
1282 				free(n, M_TCPFUNCTIONS);
1283 				break;
1284 			}
1285 		}
1286 	}
1287 	rw_wunlock(&tcp_function_lock);
1288 	return (error);
1289 }
1290 
1291 /*
1292  * Register a TCP function block using the name provided in the name
1293  * argument.
1294  *
1295  * Returns 0 on success, or an error code on failure.
1296  */
1297 int
1298 register_tcp_functions_as_name(struct tcp_function_block *blk, const char *name,
1299     int wait)
1300 {
1301 	const char *name_list[1];
1302 	int num_names, rv;
1303 
1304 	num_names = 1;
1305 	if (name != NULL)
1306 		name_list[0] = name;
1307 	else
1308 		name_list[0] = blk->tfb_tcp_block_name;
1309 	rv = register_tcp_functions_as_names(blk, wait, name_list, &num_names);
1310 	return (rv);
1311 }
1312 
1313 /*
1314  * Register a TCP function block using the name defined in
1315  * blk->tfb_tcp_block_name.
1316  *
1317  * Returns 0 on success, or an error code on failure.
1318  */
1319 int
1320 register_tcp_functions(struct tcp_function_block *blk, int wait)
1321 {
1322 
1323 	return (register_tcp_functions_as_name(blk, NULL, wait));
1324 }
1325 
1326 /*
1327  * Deregister all names associated with a function block. This
1328  * functionally removes the function block from use within the system.
1329  *
1330  * When called with a true quiesce argument, mark the function block
1331  * as being removed so no more stacks will use it and determine
1332  * whether the removal would succeed.
1333  *
1334  * When called with a false quiesce argument, actually attempt the
1335  * removal.
1336  *
1337  * When called with a force argument, attempt to switch all TCBs to
1338  * use the default stack instead of returning EBUSY.
1339  *
1340  * Returns 0 on success (or if the removal would succeed), or an error
1341  * code on failure.
1342  */
1343 int
1344 deregister_tcp_functions(struct tcp_function_block *blk, bool quiesce,
1345     bool force)
1346 {
1347 	struct tcp_function *f;
1348 	VNET_ITERATOR_DECL(vnet_iter);
1349 
1350 	if (blk == &tcp_def_funcblk) {
1351 		/* You can't un-register the default */
1352 		return (EPERM);
1353 	}
1354 	rw_wlock(&tcp_function_lock);
1355 	VNET_LIST_RLOCK_NOSLEEP();
1356 	VNET_FOREACH(vnet_iter) {
1357 		CURVNET_SET(vnet_iter);
1358 		if (blk == V_tcp_func_set_ptr) {
1359 			/* You can't free the current default in some vnet. */
1360 			CURVNET_RESTORE();
1361 			VNET_LIST_RUNLOCK_NOSLEEP();
1362 			rw_wunlock(&tcp_function_lock);
1363 			return (EBUSY);
1364 		}
1365 		CURVNET_RESTORE();
1366 	}
1367 	VNET_LIST_RUNLOCK_NOSLEEP();
1368 	/* Mark the block so no more stacks can use it. */
1369 	blk->tfb_flags |= TCP_FUNC_BEING_REMOVED;
1370 	/*
1371 	 * If TCBs are still attached to the stack, attempt to switch them
1372 	 * to the default stack.
1373 	 */
1374 	if (force && blk->tfb_refcnt) {
1375 		struct inpcb *inp;
1376 		struct tcpcb *tp;
1377 		VNET_ITERATOR_DECL(vnet_iter);
1378 
1379 		rw_wunlock(&tcp_function_lock);
1380 
1381 		VNET_LIST_RLOCK();
1382 		VNET_FOREACH(vnet_iter) {
1383 			CURVNET_SET(vnet_iter);
1384 			struct inpcb_iterator inpi = INP_ALL_ITERATOR(&V_tcbinfo,
1385 			    INPLOOKUP_WLOCKPCB);
1386 
1387 			while ((inp = inp_next(&inpi)) != NULL) {
1388 				tp = intotcpcb(inp);
1389 				if (tp == NULL || tp->t_fb != blk)
1390 					continue;
1391 				tcp_switch_back_to_default(tp);
1392 			}
1393 			CURVNET_RESTORE();
1394 		}
1395 		VNET_LIST_RUNLOCK();
1396 
1397 		rw_wlock(&tcp_function_lock);
1398 	}
1399 	if (blk->tfb_refcnt) {
1400 		/* TCBs still attached. */
1401 		rw_wunlock(&tcp_function_lock);
1402 		return (EBUSY);
1403 	}
1404 	if (quiesce) {
1405 		/* Skip removal. */
1406 		rw_wunlock(&tcp_function_lock);
1407 		return (0);
1408 	}
1409 	/* Remove any function names that map to this function block. */
1410 	while (find_tcp_fb_locked(blk, &f) != NULL) {
1411 		TAILQ_REMOVE(&t_functions, f, tf_next);
1412 		tcp_fb_cnt--;
1413 		f->tf_fb = NULL;
1414 		free(f, M_TCPFUNCTIONS);
1415 	}
1416 	rw_wunlock(&tcp_function_lock);
1417 	return (0);
1418 }
1419 
1420 static void
1421 tcp_drain(void)
1422 {
1423 	struct epoch_tracker et;
1424 	VNET_ITERATOR_DECL(vnet_iter);
1425 
1426 	if (!do_tcpdrain)
1427 		return;
1428 
1429 	NET_EPOCH_ENTER(et);
1430 	VNET_LIST_RLOCK_NOSLEEP();
1431 	VNET_FOREACH(vnet_iter) {
1432 		CURVNET_SET(vnet_iter);
1433 		struct inpcb_iterator inpi = INP_ALL_ITERATOR(&V_tcbinfo,
1434 		    INPLOOKUP_WLOCKPCB);
1435 		struct inpcb *inpb;
1436 		struct tcpcb *tcpb;
1437 
1438 	/*
1439 	 * Walk the tcpbs, if existing, and flush the reassembly queue,
1440 	 * if there is one...
1441 	 * XXX: The "Net/3" implementation doesn't imply that the TCP
1442 	 *      reassembly queue should be flushed, but in a situation
1443 	 *	where we're really low on mbufs, this is potentially
1444 	 *	useful.
1445 	 */
1446 		while ((inpb = inp_next(&inpi)) != NULL) {
1447 			if ((tcpb = intotcpcb(inpb)) != NULL) {
1448 				tcp_reass_flush(tcpb);
1449 				tcp_clean_sackreport(tcpb);
1450 #ifdef TCP_BLACKBOX
1451 				tcp_log_drain(tcpb);
1452 #endif
1453 #ifdef TCPPCAP
1454 				if (tcp_pcap_aggressive_free) {
1455 					/* Free the TCP PCAP queues. */
1456 					tcp_pcap_drain(&(tcpb->t_inpkts));
1457 					tcp_pcap_drain(&(tcpb->t_outpkts));
1458 				}
1459 #endif
1460 			}
1461 		}
1462 		CURVNET_RESTORE();
1463 	}
1464 	VNET_LIST_RUNLOCK_NOSLEEP();
1465 	NET_EPOCH_EXIT(et);
1466 }
1467 
1468 static void
1469 tcp_vnet_init(void *arg __unused)
1470 {
1471 
1472 #ifdef TCP_HHOOK
1473 	if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN,
1474 	    &V_tcp_hhh[HHOOK_TCP_EST_IN], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
1475 		printf("%s: WARNING: unable to register helper hook\n", __func__);
1476 	if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT,
1477 	    &V_tcp_hhh[HHOOK_TCP_EST_OUT], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
1478 		printf("%s: WARNING: unable to register helper hook\n", __func__);
1479 #endif
1480 #ifdef STATS
1481 	if (tcp_stats_init())
1482 		printf("%s: WARNING: unable to initialise TCP stats\n",
1483 		    __func__);
1484 #endif
1485 	in_pcbinfo_init(&V_tcbinfo, &tcpcbstor, tcp_tcbhashsize,
1486 	    tcp_tcbhashsize);
1487 
1488 	syncache_init();
1489 	tcp_hc_init();
1490 
1491 	TUNABLE_INT_FETCH("net.inet.tcp.sack.enable", &V_tcp_do_sack);
1492 	V_sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
1493 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
1494 
1495 	tcp_fastopen_init();
1496 
1497 	COUNTER_ARRAY_ALLOC(V_tcps_states, TCP_NSTATES, M_WAITOK);
1498 	VNET_PCPUSTAT_ALLOC(tcpstat, M_WAITOK);
1499 
1500 	V_tcp_msl = TCPTV_MSL;
1501 }
1502 VNET_SYSINIT(tcp_vnet_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH,
1503     tcp_vnet_init, NULL);
1504 
1505 static void
1506 tcp_init(void *arg __unused)
1507 {
1508 	int hashsize;
1509 
1510 	tcp_reass_global_init();
1511 
1512 	/* XXX virtualize those below? */
1513 	tcp_delacktime = TCPTV_DELACK;
1514 	tcp_keepinit = TCPTV_KEEP_INIT;
1515 	tcp_keepidle = TCPTV_KEEP_IDLE;
1516 	tcp_keepintvl = TCPTV_KEEPINTVL;
1517 	tcp_maxpersistidle = TCPTV_KEEP_IDLE;
1518 	tcp_rexmit_initial = TCPTV_RTOBASE;
1519 	if (tcp_rexmit_initial < 1)
1520 		tcp_rexmit_initial = 1;
1521 	tcp_rexmit_min = TCPTV_MIN;
1522 	if (tcp_rexmit_min < 1)
1523 		tcp_rexmit_min = 1;
1524 	tcp_persmin = TCPTV_PERSMIN;
1525 	tcp_persmax = TCPTV_PERSMAX;
1526 	tcp_rexmit_slop = TCPTV_CPU_VAR;
1527 	tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT;
1528 
1529 	/* Setup the tcp function block list */
1530 	TAILQ_INIT(&t_functions);
1531 	rw_init(&tcp_function_lock, "tcp_func_lock");
1532 	register_tcp_functions(&tcp_def_funcblk, M_WAITOK);
1533 	sx_init(&tcpoudp_lock, "TCP over UDP configuration");
1534 #ifdef TCP_BLACKBOX
1535 	/* Initialize the TCP logging data. */
1536 	tcp_log_init();
1537 #endif
1538 	arc4rand(&V_ts_offset_secret, sizeof(V_ts_offset_secret), 0);
1539 
1540 	if (tcp_soreceive_stream) {
1541 #ifdef INET
1542 		tcp_protosw.pr_soreceive = soreceive_stream;
1543 #endif
1544 #ifdef INET6
1545 		tcp6_protosw.pr_soreceive = soreceive_stream;
1546 #endif /* INET6 */
1547 	}
1548 
1549 #ifdef INET6
1550 	max_protohdr_grow(sizeof(struct ip6_hdr) + sizeof(struct tcphdr));
1551 #else /* INET6 */
1552 	max_protohdr_grow(sizeof(struct tcpiphdr));
1553 #endif /* INET6 */
1554 
1555 	ISN_LOCK_INIT();
1556 	EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL,
1557 		SHUTDOWN_PRI_DEFAULT);
1558 	EVENTHANDLER_REGISTER(vm_lowmem, tcp_drain, NULL, LOWMEM_PRI_DEFAULT);
1559 	EVENTHANDLER_REGISTER(mbuf_lowmem, tcp_drain, NULL, LOWMEM_PRI_DEFAULT);
1560 
1561 	tcp_inp_lro_direct_queue = counter_u64_alloc(M_WAITOK);
1562 	tcp_inp_lro_wokeup_queue = counter_u64_alloc(M_WAITOK);
1563 	tcp_inp_lro_compressed = counter_u64_alloc(M_WAITOK);
1564 	tcp_inp_lro_locks_taken = counter_u64_alloc(M_WAITOK);
1565 	tcp_extra_mbuf = counter_u64_alloc(M_WAITOK);
1566 	tcp_would_have_but = counter_u64_alloc(M_WAITOK);
1567 	tcp_comp_total = counter_u64_alloc(M_WAITOK);
1568 	tcp_uncomp_total = counter_u64_alloc(M_WAITOK);
1569 	tcp_bad_csums = counter_u64_alloc(M_WAITOK);
1570 	tcp_pacing_failures = counter_u64_alloc(M_WAITOK);
1571 #ifdef TCPPCAP
1572 	tcp_pcap_init();
1573 #endif
1574 
1575 	hashsize = tcp_tcbhashsize;
1576 	if (hashsize == 0) {
1577 		/*
1578 		 * Auto tune the hash size based on maxsockets.
1579 		 * A perfect hash would have a 1:1 mapping
1580 		 * (hashsize = maxsockets) however it's been
1581 		 * suggested that O(2) average is better.
1582 		 */
1583 		hashsize = maketcp_hashsize(maxsockets / 4);
1584 		/*
1585 		 * Our historical default is 512,
1586 		 * do not autotune lower than this.
1587 		 */
1588 		if (hashsize < 512)
1589 			hashsize = 512;
1590 		if (bootverbose)
1591 			printf("%s: %s auto tuned to %d\n", __func__,
1592 			    "net.inet.tcp.tcbhashsize", hashsize);
1593 	}
1594 	/*
1595 	 * We require a hashsize to be a power of two.
1596 	 * Previously if it was not a power of two we would just reset it
1597 	 * back to 512, which could be a nasty surprise if you did not notice
1598 	 * the error message.
1599 	 * Instead what we do is clip it to the closest power of two lower
1600 	 * than the specified hash value.
1601 	 */
1602 	if (!powerof2(hashsize)) {
1603 		int oldhashsize = hashsize;
1604 
1605 		hashsize = maketcp_hashsize(hashsize);
1606 		/* prevent absurdly low value */
1607 		if (hashsize < 16)
1608 			hashsize = 16;
1609 		printf("%s: WARNING: TCB hash size not a power of 2, "
1610 		    "clipped from %d to %d.\n", __func__, oldhashsize,
1611 		    hashsize);
1612 	}
1613 	tcp_tcbhashsize = hashsize;
1614 
1615 #ifdef INET
1616 	IPPROTO_REGISTER(IPPROTO_TCP, tcp_input, tcp_ctlinput);
1617 #endif
1618 #ifdef INET6
1619 	IP6PROTO_REGISTER(IPPROTO_TCP, tcp6_input, tcp6_ctlinput);
1620 #endif
1621 }
1622 SYSINIT(tcp_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, tcp_init, NULL);
1623 
1624 #ifdef VIMAGE
1625 static void
1626 tcp_destroy(void *unused __unused)
1627 {
1628 	int n;
1629 #ifdef TCP_HHOOK
1630 	int error;
1631 #endif
1632 
1633 	/*
1634 	 * All our processes are gone, all our sockets should be cleaned
1635 	 * up, which means, we should be past the tcp_discardcb() calls.
1636 	 * Sleep to let all tcpcb timers really disappear and cleanup.
1637 	 */
1638 	for (;;) {
1639 		INP_INFO_WLOCK(&V_tcbinfo);
1640 		n = V_tcbinfo.ipi_count;
1641 		INP_INFO_WUNLOCK(&V_tcbinfo);
1642 		if (n == 0)
1643 			break;
1644 		pause("tcpdes", hz / 10);
1645 	}
1646 	tcp_hc_destroy();
1647 	syncache_destroy();
1648 	in_pcbinfo_destroy(&V_tcbinfo);
1649 	/* tcp_discardcb() clears the sack_holes up. */
1650 	uma_zdestroy(V_sack_hole_zone);
1651 
1652 	/*
1653 	 * Cannot free the zone until all tcpcbs are released as we attach
1654 	 * the allocations to them.
1655 	 */
1656 	tcp_fastopen_destroy();
1657 
1658 	COUNTER_ARRAY_FREE(V_tcps_states, TCP_NSTATES);
1659 	VNET_PCPUSTAT_FREE(tcpstat);
1660 
1661 #ifdef TCP_HHOOK
1662 	error = hhook_head_deregister(V_tcp_hhh[HHOOK_TCP_EST_IN]);
1663 	if (error != 0) {
1664 		printf("%s: WARNING: unable to deregister helper hook "
1665 		    "type=%d, id=%d: error %d returned\n", __func__,
1666 		    HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN, error);
1667 	}
1668 	error = hhook_head_deregister(V_tcp_hhh[HHOOK_TCP_EST_OUT]);
1669 	if (error != 0) {
1670 		printf("%s: WARNING: unable to deregister helper hook "
1671 		    "type=%d, id=%d: error %d returned\n", __func__,
1672 		    HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT, error);
1673 	}
1674 #endif
1675 }
1676 VNET_SYSUNINIT(tcp, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH, tcp_destroy, NULL);
1677 #endif
1678 
1679 void
1680 tcp_fini(void *xtp)
1681 {
1682 
1683 }
1684 
1685 /*
1686  * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
1687  * tcp_template used to store this data in mbufs, but we now recopy it out
1688  * of the tcpcb each time to conserve mbufs.
1689  */
1690 void
1691 tcpip_fillheaders(struct inpcb *inp, uint16_t port, void *ip_ptr, void *tcp_ptr)
1692 {
1693 	struct tcphdr *th = (struct tcphdr *)tcp_ptr;
1694 
1695 	INP_WLOCK_ASSERT(inp);
1696 
1697 #ifdef INET6
1698 	if ((inp->inp_vflag & INP_IPV6) != 0) {
1699 		struct ip6_hdr *ip6;
1700 
1701 		ip6 = (struct ip6_hdr *)ip_ptr;
1702 		ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
1703 			(inp->inp_flow & IPV6_FLOWINFO_MASK);
1704 		ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
1705 			(IPV6_VERSION & IPV6_VERSION_MASK);
1706 		if (port == 0)
1707 			ip6->ip6_nxt = IPPROTO_TCP;
1708 		else
1709 			ip6->ip6_nxt = IPPROTO_UDP;
1710 		ip6->ip6_plen = htons(sizeof(struct tcphdr));
1711 		ip6->ip6_src = inp->in6p_laddr;
1712 		ip6->ip6_dst = inp->in6p_faddr;
1713 	}
1714 #endif /* INET6 */
1715 #if defined(INET6) && defined(INET)
1716 	else
1717 #endif
1718 #ifdef INET
1719 	{
1720 		struct ip *ip;
1721 
1722 		ip = (struct ip *)ip_ptr;
1723 		ip->ip_v = IPVERSION;
1724 		ip->ip_hl = 5;
1725 		ip->ip_tos = inp->inp_ip_tos;
1726 		ip->ip_len = 0;
1727 		ip->ip_id = 0;
1728 		ip->ip_off = 0;
1729 		ip->ip_ttl = inp->inp_ip_ttl;
1730 		ip->ip_sum = 0;
1731 		if (port == 0)
1732 			ip->ip_p = IPPROTO_TCP;
1733 		else
1734 			ip->ip_p = IPPROTO_UDP;
1735 		ip->ip_src = inp->inp_laddr;
1736 		ip->ip_dst = inp->inp_faddr;
1737 	}
1738 #endif /* INET */
1739 	th->th_sport = inp->inp_lport;
1740 	th->th_dport = inp->inp_fport;
1741 	th->th_seq = 0;
1742 	th->th_ack = 0;
1743 	th->th_off = 5;
1744 	tcp_set_flags(th, 0);
1745 	th->th_win = 0;
1746 	th->th_urp = 0;
1747 	th->th_sum = 0;		/* in_pseudo() is called later for ipv4 */
1748 }
1749 
1750 /*
1751  * Create template to be used to send tcp packets on a connection.
1752  * Allocates an mbuf and fills in a skeletal tcp/ip header.  The only
1753  * use for this function is in keepalives, which use tcp_respond.
1754  */
1755 struct tcptemp *
1756 tcpip_maketemplate(struct inpcb *inp)
1757 {
1758 	struct tcptemp *t;
1759 
1760 	t = malloc(sizeof(*t), M_TEMP, M_NOWAIT);
1761 	if (t == NULL)
1762 		return (NULL);
1763 	tcpip_fillheaders(inp, 0, (void *)&t->tt_ipgen, (void *)&t->tt_t);
1764 	return (t);
1765 }
1766 
1767 /*
1768  * Send a single message to the TCP at address specified by
1769  * the given TCP/IP header.  If m == NULL, then we make a copy
1770  * of the tcpiphdr at th and send directly to the addressed host.
1771  * This is used to force keep alive messages out using the TCP
1772  * template for a connection.  If flags are given then we send
1773  * a message back to the TCP which originated the segment th,
1774  * and discard the mbuf containing it and any other attached mbufs.
1775  *
1776  * In any case the ack and sequence number of the transmitted
1777  * segment are as specified by the parameters.
1778  *
1779  * NOTE: If m != NULL, then th must point to *inside* the mbuf.
1780  */
1781 void
1782 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
1783     tcp_seq ack, tcp_seq seq, uint16_t flags)
1784 {
1785 	struct tcpopt to;
1786 	struct inpcb *inp;
1787 	struct ip *ip;
1788 	struct mbuf *optm;
1789 	struct udphdr *uh = NULL;
1790 	struct tcphdr *nth;
1791 	struct tcp_log_buffer *lgb;
1792 	u_char *optp;
1793 #ifdef INET6
1794 	struct ip6_hdr *ip6;
1795 	int isipv6;
1796 #endif /* INET6 */
1797 	int optlen, tlen, win, ulen;
1798 	int ect = 0;
1799 	bool incl_opts;
1800 	uint16_t port;
1801 	int output_ret;
1802 #ifdef INVARIANTS
1803 	int thflags = tcp_get_flags(th);
1804 #endif
1805 
1806 	KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
1807 	NET_EPOCH_ASSERT();
1808 
1809 #ifdef INET6
1810 	isipv6 = ((struct ip *)ipgen)->ip_v == (IPV6_VERSION >> 4);
1811 	ip6 = ipgen;
1812 #endif /* INET6 */
1813 	ip = ipgen;
1814 
1815 	if (tp != NULL) {
1816 		inp = tptoinpcb(tp);
1817 		INP_LOCK_ASSERT(inp);
1818 	} else
1819 		inp = NULL;
1820 
1821 	if (m != NULL) {
1822 #ifdef INET6
1823 		if (isipv6 && ip6 && (ip6->ip6_nxt == IPPROTO_UDP))
1824 			port = m->m_pkthdr.tcp_tun_port;
1825 		else
1826 #endif
1827 		if (ip && (ip->ip_p == IPPROTO_UDP))
1828 			port = m->m_pkthdr.tcp_tun_port;
1829 		else
1830 			port = 0;
1831 	} else
1832 		port = tp->t_port;
1833 
1834 	incl_opts = false;
1835 	win = 0;
1836 	if (tp != NULL) {
1837 		if (!(flags & TH_RST)) {
1838 			win = sbspace(&inp->inp_socket->so_rcv);
1839 			if (win > TCP_MAXWIN << tp->rcv_scale)
1840 				win = TCP_MAXWIN << tp->rcv_scale;
1841 		}
1842 		if ((tp->t_flags & TF_NOOPT) == 0)
1843 			incl_opts = true;
1844 	}
1845 	if (m == NULL) {
1846 		m = m_gethdr(M_NOWAIT, MT_DATA);
1847 		if (m == NULL)
1848 			return;
1849 		m->m_data += max_linkhdr;
1850 #ifdef INET6
1851 		if (isipv6) {
1852 			bcopy((caddr_t)ip6, mtod(m, caddr_t),
1853 			      sizeof(struct ip6_hdr));
1854 			ip6 = mtod(m, struct ip6_hdr *);
1855 			nth = (struct tcphdr *)(ip6 + 1);
1856 			if (port) {
1857 				/* Insert a UDP header */
1858 				uh = (struct udphdr *)nth;
1859 				uh->uh_sport = htons(V_tcp_udp_tunneling_port);
1860 				uh->uh_dport = port;
1861 				nth = (struct tcphdr *)(uh + 1);
1862 			}
1863 		} else
1864 #endif /* INET6 */
1865 		{
1866 			bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
1867 			ip = mtod(m, struct ip *);
1868 			nth = (struct tcphdr *)(ip + 1);
1869 			if (port) {
1870 				/* Insert a UDP header */
1871 				uh = (struct udphdr *)nth;
1872 				uh->uh_sport = htons(V_tcp_udp_tunneling_port);
1873 				uh->uh_dport = port;
1874 				nth = (struct tcphdr *)(uh + 1);
1875 			}
1876 		}
1877 		bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
1878 		flags = TH_ACK;
1879 	} else if ((!M_WRITABLE(m)) || (port != 0)) {
1880 		struct mbuf *n;
1881 
1882 		/* Can't reuse 'm', allocate a new mbuf. */
1883 		n = m_gethdr(M_NOWAIT, MT_DATA);
1884 		if (n == NULL) {
1885 			m_freem(m);
1886 			return;
1887 		}
1888 
1889 		if (!m_dup_pkthdr(n, m, M_NOWAIT)) {
1890 			m_freem(m);
1891 			m_freem(n);
1892 			return;
1893 		}
1894 
1895 		n->m_data += max_linkhdr;
1896 		/* m_len is set later */
1897 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
1898 #ifdef INET6
1899 		if (isipv6) {
1900 			bcopy((caddr_t)ip6, mtod(n, caddr_t),
1901 			      sizeof(struct ip6_hdr));
1902 			ip6 = mtod(n, struct ip6_hdr *);
1903 			xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
1904 			nth = (struct tcphdr *)(ip6 + 1);
1905 			if (port) {
1906 				/* Insert a UDP header */
1907 				uh = (struct udphdr *)nth;
1908 				uh->uh_sport = htons(V_tcp_udp_tunneling_port);
1909 				uh->uh_dport = port;
1910 				nth = (struct tcphdr *)(uh + 1);
1911 			}
1912 		} else
1913 #endif /* INET6 */
1914 		{
1915 			bcopy((caddr_t)ip, mtod(n, caddr_t), sizeof(struct ip));
1916 			ip = mtod(n, struct ip *);
1917 			xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t);
1918 			nth = (struct tcphdr *)(ip + 1);
1919 			if (port) {
1920 				/* Insert a UDP header */
1921 				uh = (struct udphdr *)nth;
1922 				uh->uh_sport = htons(V_tcp_udp_tunneling_port);
1923 				uh->uh_dport = port;
1924 				nth = (struct tcphdr *)(uh + 1);
1925 			}
1926 		}
1927 		bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
1928 		xchg(nth->th_dport, nth->th_sport, uint16_t);
1929 		th = nth;
1930 		m_freem(m);
1931 		m = n;
1932 	} else {
1933 		/*
1934 		 *  reuse the mbuf.
1935 		 * XXX MRT We inherit the FIB, which is lucky.
1936 		 */
1937 		m_freem(m->m_next);
1938 		m->m_next = NULL;
1939 		m->m_data = (caddr_t)ipgen;
1940 		/* clear any receive flags for proper bpf timestamping */
1941 		m->m_flags &= ~(M_TSTMP | M_TSTMP_LRO);
1942 		/* m_len is set later */
1943 #ifdef INET6
1944 		if (isipv6) {
1945 			xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
1946 			nth = (struct tcphdr *)(ip6 + 1);
1947 		} else
1948 #endif /* INET6 */
1949 		{
1950 			xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t);
1951 			nth = (struct tcphdr *)(ip + 1);
1952 		}
1953 		if (th != nth) {
1954 			/*
1955 			 * this is usually a case when an extension header
1956 			 * exists between the IPv6 header and the
1957 			 * TCP header.
1958 			 */
1959 			nth->th_sport = th->th_sport;
1960 			nth->th_dport = th->th_dport;
1961 		}
1962 		xchg(nth->th_dport, nth->th_sport, uint16_t);
1963 #undef xchg
1964 	}
1965 	tlen = 0;
1966 #ifdef INET6
1967 	if (isipv6)
1968 		tlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
1969 #endif
1970 #if defined(INET) && defined(INET6)
1971 	else
1972 #endif
1973 #ifdef INET
1974 		tlen = sizeof (struct tcpiphdr);
1975 #endif
1976 	if (port)
1977 		tlen += sizeof (struct udphdr);
1978 #ifdef INVARIANTS
1979 	m->m_len = 0;
1980 	KASSERT(M_TRAILINGSPACE(m) >= tlen,
1981 	    ("Not enough trailing space for message (m=%p, need=%d, have=%ld)",
1982 	    m, tlen, (long)M_TRAILINGSPACE(m)));
1983 #endif
1984 	m->m_len = tlen;
1985 	to.to_flags = 0;
1986 	if (incl_opts) {
1987 		ect = tcp_ecn_output_established(tp, &flags, 0, false);
1988 		/* Make sure we have room. */
1989 		if (M_TRAILINGSPACE(m) < TCP_MAXOLEN) {
1990 			m->m_next = m_get(M_NOWAIT, MT_DATA);
1991 			if (m->m_next) {
1992 				optp = mtod(m->m_next, u_char *);
1993 				optm = m->m_next;
1994 			} else
1995 				incl_opts = false;
1996 		} else {
1997 			optp = (u_char *) (nth + 1);
1998 			optm = m;
1999 		}
2000 	}
2001 	if (incl_opts) {
2002 		/* Timestamps. */
2003 		if (tp->t_flags & TF_RCVD_TSTMP) {
2004 			to.to_tsval = tcp_ts_getticks() + tp->ts_offset;
2005 			to.to_tsecr = tp->ts_recent;
2006 			to.to_flags |= TOF_TS;
2007 		}
2008 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
2009 		/* TCP-MD5 (RFC2385). */
2010 		if (tp->t_flags & TF_SIGNATURE)
2011 			to.to_flags |= TOF_SIGNATURE;
2012 #endif
2013 		/* Add the options. */
2014 		tlen += optlen = tcp_addoptions(&to, optp);
2015 
2016 		/* Update m_len in the correct mbuf. */
2017 		optm->m_len += optlen;
2018 	} else
2019 		optlen = 0;
2020 #ifdef INET6
2021 	if (isipv6) {
2022 		if (uh) {
2023 			ulen = tlen - sizeof(struct ip6_hdr);
2024 			uh->uh_ulen = htons(ulen);
2025 		}
2026 		ip6->ip6_flow = htonl(ect << IPV6_FLOWLABEL_LEN);
2027 		ip6->ip6_vfc = IPV6_VERSION;
2028 		if (port)
2029 			ip6->ip6_nxt = IPPROTO_UDP;
2030 		else
2031 			ip6->ip6_nxt = IPPROTO_TCP;
2032 		ip6->ip6_plen = htons(tlen - sizeof(*ip6));
2033 	}
2034 #endif
2035 #if defined(INET) && defined(INET6)
2036 	else
2037 #endif
2038 #ifdef INET
2039 	{
2040 		if (uh) {
2041 			ulen = tlen - sizeof(struct ip);
2042 			uh->uh_ulen = htons(ulen);
2043 		}
2044 		ip->ip_len = htons(tlen);
2045 		if (inp != NULL) {
2046 			ip->ip_tos = inp->inp_ip_tos & ~IPTOS_ECN_MASK;
2047 			ip->ip_ttl = inp->inp_ip_ttl;
2048 		} else {
2049 			ip->ip_tos = 0;
2050 			ip->ip_ttl = V_ip_defttl;
2051 		}
2052 		ip->ip_tos |= ect;
2053 		if (port) {
2054 			ip->ip_p = IPPROTO_UDP;
2055 		} else {
2056 			ip->ip_p = IPPROTO_TCP;
2057 		}
2058 		if (V_path_mtu_discovery)
2059 			ip->ip_off |= htons(IP_DF);
2060 	}
2061 #endif
2062 	m->m_pkthdr.len = tlen;
2063 	m->m_pkthdr.rcvif = NULL;
2064 #ifdef MAC
2065 	if (inp != NULL) {
2066 		/*
2067 		 * Packet is associated with a socket, so allow the
2068 		 * label of the response to reflect the socket label.
2069 		 */
2070 		INP_LOCK_ASSERT(inp);
2071 		mac_inpcb_create_mbuf(inp, m);
2072 	} else {
2073 		/*
2074 		 * Packet is not associated with a socket, so possibly
2075 		 * update the label in place.
2076 		 */
2077 		mac_netinet_tcp_reply(m);
2078 	}
2079 #endif
2080 	nth->th_seq = htonl(seq);
2081 	nth->th_ack = htonl(ack);
2082 	nth->th_off = (sizeof (struct tcphdr) + optlen) >> 2;
2083 	tcp_set_flags(nth, flags);
2084 	if (tp && (flags & TH_RST)) {
2085 		/* Log the reset */
2086 		tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST);
2087 	}
2088 	if (tp != NULL)
2089 		nth->th_win = htons((u_short) (win >> tp->rcv_scale));
2090 	else
2091 		nth->th_win = htons((u_short)win);
2092 	nth->th_urp = 0;
2093 
2094 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
2095 	if (to.to_flags & TOF_SIGNATURE) {
2096 		if (!TCPMD5_ENABLED() ||
2097 		    TCPMD5_OUTPUT(m, nth, to.to_signature) != 0) {
2098 			m_freem(m);
2099 			return;
2100 		}
2101 	}
2102 #endif
2103 
2104 #ifdef INET6
2105 	if (isipv6) {
2106 		if (port) {
2107 			m->m_pkthdr.csum_flags = CSUM_UDP_IPV6;
2108 			m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
2109 			uh->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0);
2110 			nth->th_sum = 0;
2111 		} else {
2112 			m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
2113 			m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
2114 			nth->th_sum = in6_cksum_pseudo(ip6,
2115 			    tlen - sizeof(struct ip6_hdr), IPPROTO_TCP, 0);
2116 		}
2117 		ip6->ip6_hlim = in6_selecthlim(inp, NULL);
2118 	}
2119 #endif /* INET6 */
2120 #if defined(INET6) && defined(INET)
2121 	else
2122 #endif
2123 #ifdef INET
2124 	{
2125 		if (port) {
2126 			uh->uh_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
2127 			    htons(ulen + IPPROTO_UDP));
2128 			m->m_pkthdr.csum_flags = CSUM_UDP;
2129 			m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
2130 			nth->th_sum = 0;
2131 		} else {
2132 			m->m_pkthdr.csum_flags = CSUM_TCP;
2133 			m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
2134 			nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
2135 			    htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
2136 		}
2137 	}
2138 #endif /* INET */
2139 	TCP_PROBE3(debug__output, tp, th, m);
2140 	if (flags & TH_RST)
2141 		TCP_PROBE5(accept__refused, NULL, NULL, m, tp, nth);
2142 	lgb = NULL;
2143 	if ((tp != NULL) && tcp_bblogging_on(tp)) {
2144 		if (INP_WLOCKED(inp)) {
2145 			union tcp_log_stackspecific log;
2146 			struct timeval tv;
2147 
2148 			memset(&log.u_bbr, 0, sizeof(log.u_bbr));
2149 			log.u_bbr.inhpts = tcp_in_hpts(tp);
2150 			log.u_bbr.flex8 = 4;
2151 			log.u_bbr.pkts_out = tp->t_maxseg;
2152 			log.u_bbr.timeStamp = tcp_get_usecs(&tv);
2153 			log.u_bbr.delivered = 0;
2154 			lgb = tcp_log_event(tp, nth, NULL, NULL, TCP_LOG_OUT,
2155 			    ERRNO_UNK, 0, &log, false, NULL, NULL, 0, &tv);
2156 		} else {
2157 			/*
2158 			 * We can not log the packet, since we only own the
2159 			 * read lock, but a write lock is needed. The read lock
2160 			 * is not upgraded to a write lock, since only getting
2161 			 * the read lock was done intentionally to improve the
2162 			 * handling of SYN flooding attacks.
2163 			 * This happens only for pure SYN segments received in
2164 			 * the initial CLOSED state, or received in a more
2165 			 * advanced state than listen and the UDP encapsulation
2166 			 * port is unexpected.
2167 			 * The incoming SYN segments do not really belong to
2168 			 * the TCP connection and the handling does not change
2169 			 * the state of the TCP connection. Therefore, the
2170 			 * sending of the RST segments is not logged. Please
2171 			 * note that also the incoming SYN segments are not
2172 			 * logged.
2173 			 *
2174 			 * The following code ensures that the above description
2175 			 * is and stays correct.
2176 			 */
2177 			KASSERT((thflags & (TH_ACK|TH_SYN)) == TH_SYN &&
2178 			    (tp->t_state == TCPS_CLOSED ||
2179 			    (tp->t_state > TCPS_LISTEN && tp->t_port != port)),
2180 			    ("%s: Logging of TCP segment with flags 0x%b and "
2181 			    "UDP encapsulation port %u skipped in state %s",
2182 			    __func__, thflags, PRINT_TH_FLAGS,
2183 			    ntohs(port), tcpstates[tp->t_state]));
2184 		}
2185 	}
2186 
2187 	if (flags & TH_ACK)
2188 		TCPSTAT_INC(tcps_sndacks);
2189 	else if (flags & (TH_SYN|TH_FIN|TH_RST))
2190 		TCPSTAT_INC(tcps_sndctrl);
2191 	TCPSTAT_INC(tcps_sndtotal);
2192 
2193 #ifdef INET6
2194 	if (isipv6) {
2195 		TCP_PROBE5(send, NULL, tp, ip6, tp, nth);
2196 		output_ret = ip6_output(m, inp ? inp->in6p_outputopts : NULL,
2197 		    NULL, 0, NULL, NULL, inp);
2198 	}
2199 #endif /* INET6 */
2200 #if defined(INET) && defined(INET6)
2201 	else
2202 #endif
2203 #ifdef INET
2204 	{
2205 		TCP_PROBE5(send, NULL, tp, ip, tp, nth);
2206 		output_ret = ip_output(m, NULL, NULL, 0, NULL, inp);
2207 	}
2208 #endif
2209 	if (lgb != NULL)
2210 		lgb->tlb_errno = output_ret;
2211 }
2212 
2213 /*
2214  * Create a new TCP control block, making an empty reassembly queue and hooking
2215  * it to the argument protocol control block.  The `inp' parameter must have
2216  * come from the zone allocator set up by tcpcbstor declaration.
2217  */
2218 struct tcpcb *
2219 tcp_newtcpcb(struct inpcb *inp)
2220 {
2221 	struct tcpcb *tp = intotcpcb(inp);
2222 #ifdef INET6
2223 	int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
2224 #endif /* INET6 */
2225 
2226 	/*
2227 	 * Historically allocation was done with M_ZERO.  There is a lot of
2228 	 * code that rely on that.  For now take safe approach and zero whole
2229 	 * tcpcb.  This definitely can be optimized.
2230 	 */
2231 	bzero(&tp->t_start_zero, t_zero_size);
2232 
2233 	/* Initialise cc_var struct for this tcpcb. */
2234 	tp->t_ccv.type = IPPROTO_TCP;
2235 	tp->t_ccv.ccvc.tcp = tp;
2236 	rw_rlock(&tcp_function_lock);
2237 	tp->t_fb = V_tcp_func_set_ptr;
2238 	refcount_acquire(&tp->t_fb->tfb_refcnt);
2239 	rw_runlock(&tcp_function_lock);
2240 	/*
2241 	 * Use the current system default CC algorithm.
2242 	 */
2243 	cc_attach(tp, CC_DEFAULT_ALGO());
2244 
2245 	if (CC_ALGO(tp)->cb_init != NULL)
2246 		if (CC_ALGO(tp)->cb_init(&tp->t_ccv, NULL) > 0) {
2247 			cc_detach(tp);
2248 			if (tp->t_fb->tfb_tcp_fb_fini)
2249 				(*tp->t_fb->tfb_tcp_fb_fini)(tp, 1);
2250 			refcount_release(&tp->t_fb->tfb_refcnt);
2251 			return (NULL);
2252 		}
2253 
2254 #ifdef TCP_HHOOK
2255 	if (khelp_init_osd(HELPER_CLASS_TCP, &tp->t_osd)) {
2256 		if (tp->t_fb->tfb_tcp_fb_fini)
2257 			(*tp->t_fb->tfb_tcp_fb_fini)(tp, 1);
2258 		refcount_release(&tp->t_fb->tfb_refcnt);
2259 		return (NULL);
2260 	}
2261 #endif
2262 
2263 	TAILQ_INIT(&tp->t_segq);
2264 	STAILQ_INIT(&tp->t_inqueue);
2265 	tp->t_maxseg =
2266 #ifdef INET6
2267 		isipv6 ? V_tcp_v6mssdflt :
2268 #endif /* INET6 */
2269 		V_tcp_mssdflt;
2270 
2271 	/* All mbuf queue/ack compress flags should be off */
2272 	tcp_lro_features_off(tp);
2273 
2274 	callout_init_rw(&tp->t_callout, &inp->inp_lock, CALLOUT_RETURNUNLOCKED);
2275 	for (int i = 0; i < TT_N; i++)
2276 		tp->t_timers[i] = SBT_MAX;
2277 
2278 	switch (V_tcp_do_rfc1323) {
2279 		case 0:
2280 			break;
2281 		default:
2282 		case 1:
2283 			tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
2284 			break;
2285 		case 2:
2286 			tp->t_flags = TF_REQ_SCALE;
2287 			break;
2288 		case 3:
2289 			tp->t_flags = TF_REQ_TSTMP;
2290 			break;
2291 	}
2292 	if (V_tcp_do_sack)
2293 		tp->t_flags |= TF_SACK_PERMIT;
2294 	TAILQ_INIT(&tp->snd_holes);
2295 
2296 	/*
2297 	 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
2298 	 * rtt estimate.  Set rttvar so that srtt + 4 * rttvar gives
2299 	 * reasonable initial retransmit time.
2300 	 */
2301 	tp->t_srtt = TCPTV_SRTTBASE;
2302 	tp->t_rttvar = ((tcp_rexmit_initial - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
2303 	tp->t_rttmin = tcp_rexmit_min;
2304 	tp->t_rxtcur = tcp_rexmit_initial;
2305 	tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
2306 	tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
2307 	tp->t_rcvtime = ticks;
2308 	/* We always start with ticks granularity */
2309 	tp->t_tmr_granularity = TCP_TMR_GRANULARITY_TICKS;
2310 	/*
2311 	 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
2312 	 * because the socket may be bound to an IPv6 wildcard address,
2313 	 * which may match an IPv4-mapped IPv6 address.
2314 	 */
2315 	inp->inp_ip_ttl = V_ip_defttl;
2316 #ifdef TCPHPTS
2317 	tcp_hpts_init(tp);
2318 #endif
2319 #ifdef TCPPCAP
2320 	/*
2321 	 * Init the TCP PCAP queues.
2322 	 */
2323 	tcp_pcap_tcpcb_init(tp);
2324 #endif
2325 #ifdef TCP_BLACKBOX
2326 	/* Initialize the per-TCPCB log data. */
2327 	tcp_log_tcpcbinit(tp);
2328 #endif
2329 	tp->t_pacing_rate = -1;
2330 	if (tp->t_fb->tfb_tcp_fb_init) {
2331 		if ((*tp->t_fb->tfb_tcp_fb_init)(tp, &tp->t_fb_ptr)) {
2332 			refcount_release(&tp->t_fb->tfb_refcnt);
2333 			return (NULL);
2334 		}
2335 	}
2336 #ifdef STATS
2337 	if (V_tcp_perconn_stats_enable == 1)
2338 		tp->t_stats = stats_blob_alloc(V_tcp_perconn_stats_dflt_tpl, 0);
2339 #endif
2340 	if (V_tcp_do_lrd)
2341 		tp->t_flags |= TF_LRD;
2342 
2343 	return (tp);
2344 }
2345 
2346 /*
2347  * Drop a TCP connection, reporting
2348  * the specified error.  If connection is synchronized,
2349  * then send a RST to peer.
2350  */
2351 struct tcpcb *
2352 tcp_drop(struct tcpcb *tp, int errno)
2353 {
2354 	struct socket *so = tptosocket(tp);
2355 
2356 	NET_EPOCH_ASSERT();
2357 	INP_WLOCK_ASSERT(tptoinpcb(tp));
2358 
2359 	if (TCPS_HAVERCVDSYN(tp->t_state)) {
2360 		tcp_state_change(tp, TCPS_CLOSED);
2361 		/* Don't use tcp_output() here due to possible recursion. */
2362 		(void)tcp_output_nodrop(tp);
2363 		TCPSTAT_INC(tcps_drops);
2364 	} else
2365 		TCPSTAT_INC(tcps_conndrops);
2366 	if (errno == ETIMEDOUT && tp->t_softerror)
2367 		errno = tp->t_softerror;
2368 	so->so_error = errno;
2369 	return (tcp_close(tp));
2370 }
2371 
2372 void
2373 tcp_discardcb(struct tcpcb *tp)
2374 {
2375 	struct inpcb *inp = tptoinpcb(tp);
2376 	struct socket *so = tptosocket(tp);
2377 	struct mbuf *m;
2378 #ifdef INET6
2379 	bool isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
2380 #endif
2381 
2382 	INP_WLOCK_ASSERT(inp);
2383 
2384 	tcp_timer_stop(tp);
2385 	if (tp->t_fb->tfb_tcp_timer_stop_all) {
2386 		tp->t_fb->tfb_tcp_timer_stop_all(tp);
2387 	}
2388 
2389 	/* free the reassembly queue, if any */
2390 	tcp_reass_flush(tp);
2391 
2392 #ifdef TCP_OFFLOAD
2393 	/* Disconnect offload device, if any. */
2394 	if (tp->t_flags & TF_TOE)
2395 		tcp_offload_detach(tp);
2396 #endif
2397 
2398 	tcp_free_sackholes(tp);
2399 
2400 #ifdef TCPPCAP
2401 	/* Free the TCP PCAP queues. */
2402 	tcp_pcap_drain(&(tp->t_inpkts));
2403 	tcp_pcap_drain(&(tp->t_outpkts));
2404 #endif
2405 
2406 	/* Allow the CC algorithm to clean up after itself. */
2407 	if (CC_ALGO(tp)->cb_destroy != NULL)
2408 		CC_ALGO(tp)->cb_destroy(&tp->t_ccv);
2409 	CC_DATA(tp) = NULL;
2410 	/* Detach from the CC algorithm */
2411 	cc_detach(tp);
2412 
2413 #ifdef TCP_HHOOK
2414 	khelp_destroy_osd(&tp->t_osd);
2415 #endif
2416 #ifdef STATS
2417 	stats_blob_destroy(tp->t_stats);
2418 #endif
2419 
2420 	CC_ALGO(tp) = NULL;
2421 	if ((m = STAILQ_FIRST(&tp->t_inqueue)) != NULL) {
2422 		struct mbuf *prev;
2423 
2424 		STAILQ_INIT(&tp->t_inqueue);
2425 		STAILQ_FOREACH_FROM_SAFE(m, &tp->t_inqueue, m_stailqpkt, prev)
2426 			m_freem(m);
2427 	}
2428 	TCPSTATES_DEC(tp->t_state);
2429 
2430 	if (tp->t_fb->tfb_tcp_fb_fini)
2431 		(*tp->t_fb->tfb_tcp_fb_fini)(tp, 1);
2432 	MPASS(!tcp_in_hpts(tp));
2433 #ifdef TCP_BLACKBOX
2434 	tcp_log_tcpcbfini(tp);
2435 #endif
2436 
2437 	/*
2438 	 * If we got enough samples through the srtt filter,
2439 	 * save the rtt and rttvar in the routing entry.
2440 	 * 'Enough' is arbitrarily defined as 4 rtt samples.
2441 	 * 4 samples is enough for the srtt filter to converge
2442 	 * to within enough % of the correct value; fewer samples
2443 	 * and we could save a bogus rtt. The danger is not high
2444 	 * as tcp quickly recovers from everything.
2445 	 * XXX: Works very well but needs some more statistics!
2446 	 *
2447 	 * XXXRRS: Updating must be after the stack fini() since
2448 	 * that may be converting some internal representation of
2449 	 * say srtt etc into the general one used by other stacks.
2450 	 * Lets also at least protect against the so being NULL
2451 	 * as RW stated below.
2452 	 */
2453 	if ((tp->t_rttupdated >= 4) && (so != NULL)) {
2454 		struct hc_metrics_lite metrics;
2455 		uint32_t ssthresh;
2456 
2457 		bzero(&metrics, sizeof(metrics));
2458 		/*
2459 		 * Update the ssthresh always when the conditions below
2460 		 * are satisfied. This gives us better new start value
2461 		 * for the congestion avoidance for new connections.
2462 		 * ssthresh is only set if packet loss occurred on a session.
2463 		 *
2464 		 * XXXRW: 'so' may be NULL here, and/or socket buffer may be
2465 		 * being torn down.  Ideally this code would not use 'so'.
2466 		 */
2467 		ssthresh = tp->snd_ssthresh;
2468 		if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) {
2469 			/*
2470 			 * convert the limit from user data bytes to
2471 			 * packets then to packet data bytes.
2472 			 */
2473 			ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg;
2474 			if (ssthresh < 2)
2475 				ssthresh = 2;
2476 			ssthresh *= (tp->t_maxseg +
2477 #ifdef INET6
2478 			    (isipv6 ? sizeof (struct ip6_hdr) +
2479 			    sizeof (struct tcphdr) :
2480 #endif
2481 			    sizeof (struct tcpiphdr)
2482 #ifdef INET6
2483 			    )
2484 #endif
2485 			    );
2486 		} else
2487 			ssthresh = 0;
2488 		metrics.rmx_ssthresh = ssthresh;
2489 
2490 		metrics.rmx_rtt = tp->t_srtt;
2491 		metrics.rmx_rttvar = tp->t_rttvar;
2492 		metrics.rmx_cwnd = tp->snd_cwnd;
2493 		metrics.rmx_sendpipe = 0;
2494 		metrics.rmx_recvpipe = 0;
2495 
2496 		tcp_hc_update(&inp->inp_inc, &metrics);
2497 	}
2498 
2499 	refcount_release(&tp->t_fb->tfb_refcnt);
2500 }
2501 
2502 /*
2503  * Attempt to close a TCP control block, marking it as dropped, and freeing
2504  * the socket if we hold the only reference.
2505  */
2506 struct tcpcb *
2507 tcp_close(struct tcpcb *tp)
2508 {
2509 	struct inpcb *inp = tptoinpcb(tp);
2510 	struct socket *so = tptosocket(tp);
2511 
2512 	INP_WLOCK_ASSERT(inp);
2513 
2514 #ifdef TCP_OFFLOAD
2515 	if (tp->t_state == TCPS_LISTEN)
2516 		tcp_offload_listen_stop(tp);
2517 #endif
2518 	/*
2519 	 * This releases the TFO pending counter resource for TFO listen
2520 	 * sockets as well as passively-created TFO sockets that transition
2521 	 * from SYN_RECEIVED to CLOSED.
2522 	 */
2523 	if (tp->t_tfo_pending) {
2524 		tcp_fastopen_decrement_counter(tp->t_tfo_pending);
2525 		tp->t_tfo_pending = NULL;
2526 	}
2527 #ifdef TCPHPTS
2528 	tcp_hpts_remove(tp);
2529 #endif
2530 	in_pcbdrop(inp);
2531 	TCPSTAT_INC(tcps_closed);
2532 	if (tp->t_state != TCPS_CLOSED)
2533 		tcp_state_change(tp, TCPS_CLOSED);
2534 	KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL"));
2535 	soisdisconnected(so);
2536 	if (inp->inp_flags & INP_SOCKREF) {
2537 		inp->inp_flags &= ~INP_SOCKREF;
2538 		INP_WUNLOCK(inp);
2539 		sorele(so);
2540 		return (NULL);
2541 	}
2542 	return (tp);
2543 }
2544 
2545 /*
2546  * Notify a tcp user of an asynchronous error;
2547  * store error as soft error, but wake up user
2548  * (for now, won't do anything until can select for soft error).
2549  *
2550  * Do not wake up user since there currently is no mechanism for
2551  * reporting soft errors (yet - a kqueue filter may be added).
2552  */
2553 static struct inpcb *
2554 tcp_notify(struct inpcb *inp, int error)
2555 {
2556 	struct tcpcb *tp;
2557 
2558 	INP_WLOCK_ASSERT(inp);
2559 
2560 	tp = intotcpcb(inp);
2561 	KASSERT(tp != NULL, ("tcp_notify: tp == NULL"));
2562 
2563 	/*
2564 	 * Ignore some errors if we are hooked up.
2565 	 * If connection hasn't completed, has retransmitted several times,
2566 	 * and receives a second error, give up now.  This is better
2567 	 * than waiting a long time to establish a connection that
2568 	 * can never complete.
2569 	 */
2570 	if (tp->t_state == TCPS_ESTABLISHED &&
2571 	    (error == EHOSTUNREACH || error == ENETUNREACH ||
2572 	     error == EHOSTDOWN)) {
2573 		if (inp->inp_route.ro_nh) {
2574 			NH_FREE(inp->inp_route.ro_nh);
2575 			inp->inp_route.ro_nh = (struct nhop_object *)NULL;
2576 		}
2577 		return (inp);
2578 	} else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
2579 	    tp->t_softerror) {
2580 		tp = tcp_drop(tp, error);
2581 		if (tp != NULL)
2582 			return (inp);
2583 		else
2584 			return (NULL);
2585 	} else {
2586 		tp->t_softerror = error;
2587 		return (inp);
2588 	}
2589 #if 0
2590 	wakeup( &so->so_timeo);
2591 	sorwakeup(so);
2592 	sowwakeup(so);
2593 #endif
2594 }
2595 
2596 static int
2597 tcp_pcblist(SYSCTL_HANDLER_ARGS)
2598 {
2599 	struct inpcb_iterator inpi = INP_ALL_ITERATOR(&V_tcbinfo,
2600 	    INPLOOKUP_RLOCKPCB);
2601 	struct xinpgen xig;
2602 	struct inpcb *inp;
2603 	int error;
2604 
2605 	if (req->newptr != NULL)
2606 		return (EPERM);
2607 
2608 	if (req->oldptr == NULL) {
2609 		int n;
2610 
2611 		n = V_tcbinfo.ipi_count +
2612 		    counter_u64_fetch(V_tcps_states[TCPS_SYN_RECEIVED]);
2613 		n += imax(n / 8, 10);
2614 		req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xtcpcb);
2615 		return (0);
2616 	}
2617 
2618 	if ((error = sysctl_wire_old_buffer(req, 0)) != 0)
2619 		return (error);
2620 
2621 	bzero(&xig, sizeof(xig));
2622 	xig.xig_len = sizeof xig;
2623 	xig.xig_count = V_tcbinfo.ipi_count +
2624 	    counter_u64_fetch(V_tcps_states[TCPS_SYN_RECEIVED]);
2625 	xig.xig_gen = V_tcbinfo.ipi_gencnt;
2626 	xig.xig_sogen = so_gencnt;
2627 	error = SYSCTL_OUT(req, &xig, sizeof xig);
2628 	if (error)
2629 		return (error);
2630 
2631 	error = syncache_pcblist(req);
2632 	if (error)
2633 		return (error);
2634 
2635 	while ((inp = inp_next(&inpi)) != NULL) {
2636 		if (inp->inp_gencnt <= xig.xig_gen &&
2637 		    cr_canseeinpcb(req->td->td_ucred, inp) == 0) {
2638 			struct xtcpcb xt;
2639 
2640 			tcp_inptoxtp(inp, &xt);
2641 			error = SYSCTL_OUT(req, &xt, sizeof xt);
2642 			if (error) {
2643 				INP_RUNLOCK(inp);
2644 				break;
2645 			} else
2646 				continue;
2647 		}
2648 	}
2649 
2650 	if (!error) {
2651 		/*
2652 		 * Give the user an updated idea of our state.
2653 		 * If the generation differs from what we told
2654 		 * her before, she knows that something happened
2655 		 * while we were processing this request, and it
2656 		 * might be necessary to retry.
2657 		 */
2658 		xig.xig_gen = V_tcbinfo.ipi_gencnt;
2659 		xig.xig_sogen = so_gencnt;
2660 		xig.xig_count = V_tcbinfo.ipi_count +
2661 		    counter_u64_fetch(V_tcps_states[TCPS_SYN_RECEIVED]);
2662 		error = SYSCTL_OUT(req, &xig, sizeof xig);
2663 	}
2664 
2665 	return (error);
2666 }
2667 
2668 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist,
2669     CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_NEEDGIANT,
2670     NULL, 0, tcp_pcblist, "S,xtcpcb",
2671     "List of active TCP connections");
2672 
2673 #ifdef INET
2674 static int
2675 tcp_getcred(SYSCTL_HANDLER_ARGS)
2676 {
2677 	struct xucred xuc;
2678 	struct sockaddr_in addrs[2];
2679 	struct epoch_tracker et;
2680 	struct inpcb *inp;
2681 	int error;
2682 
2683 	error = priv_check(req->td, PRIV_NETINET_GETCRED);
2684 	if (error)
2685 		return (error);
2686 	error = SYSCTL_IN(req, addrs, sizeof(addrs));
2687 	if (error)
2688 		return (error);
2689 	NET_EPOCH_ENTER(et);
2690 	inp = in_pcblookup(&V_tcbinfo, addrs[1].sin_addr, addrs[1].sin_port,
2691 	    addrs[0].sin_addr, addrs[0].sin_port, INPLOOKUP_RLOCKPCB, NULL);
2692 	NET_EPOCH_EXIT(et);
2693 	if (inp != NULL) {
2694 		if (error == 0)
2695 			error = cr_canseeinpcb(req->td->td_ucred, inp);
2696 		if (error == 0)
2697 			cru2x(inp->inp_cred, &xuc);
2698 		INP_RUNLOCK(inp);
2699 	} else
2700 		error = ENOENT;
2701 	if (error == 0)
2702 		error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
2703 	return (error);
2704 }
2705 
2706 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
2707     CTLTYPE_OPAQUE | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_NEEDGIANT,
2708     0, 0, tcp_getcred, "S,xucred",
2709     "Get the xucred of a TCP connection");
2710 #endif /* INET */
2711 
2712 #ifdef INET6
2713 static int
2714 tcp6_getcred(SYSCTL_HANDLER_ARGS)
2715 {
2716 	struct epoch_tracker et;
2717 	struct xucred xuc;
2718 	struct sockaddr_in6 addrs[2];
2719 	struct inpcb *inp;
2720 	int error;
2721 #ifdef INET
2722 	int mapped = 0;
2723 #endif
2724 
2725 	error = priv_check(req->td, PRIV_NETINET_GETCRED);
2726 	if (error)
2727 		return (error);
2728 	error = SYSCTL_IN(req, addrs, sizeof(addrs));
2729 	if (error)
2730 		return (error);
2731 	if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 ||
2732 	    (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) {
2733 		return (error);
2734 	}
2735 	if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
2736 #ifdef INET
2737 		if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
2738 			mapped = 1;
2739 		else
2740 #endif
2741 			return (EINVAL);
2742 	}
2743 
2744 	NET_EPOCH_ENTER(et);
2745 #ifdef INET
2746 	if (mapped == 1)
2747 		inp = in_pcblookup(&V_tcbinfo,
2748 			*(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
2749 			addrs[1].sin6_port,
2750 			*(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
2751 			addrs[0].sin6_port, INPLOOKUP_RLOCKPCB, NULL);
2752 	else
2753 #endif
2754 		inp = in6_pcblookup(&V_tcbinfo,
2755 			&addrs[1].sin6_addr, addrs[1].sin6_port,
2756 			&addrs[0].sin6_addr, addrs[0].sin6_port,
2757 			INPLOOKUP_RLOCKPCB, NULL);
2758 	NET_EPOCH_EXIT(et);
2759 	if (inp != NULL) {
2760 		if (error == 0)
2761 			error = cr_canseeinpcb(req->td->td_ucred, inp);
2762 		if (error == 0)
2763 			cru2x(inp->inp_cred, &xuc);
2764 		INP_RUNLOCK(inp);
2765 	} else
2766 		error = ENOENT;
2767 	if (error == 0)
2768 		error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
2769 	return (error);
2770 }
2771 
2772 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
2773     CTLTYPE_OPAQUE | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_NEEDGIANT,
2774     0, 0, tcp6_getcred, "S,xucred",
2775     "Get the xucred of a TCP6 connection");
2776 #endif /* INET6 */
2777 
2778 #ifdef INET
2779 /* Path MTU to try next when a fragmentation-needed message is received. */
2780 static inline int
2781 tcp_next_pmtu(const struct icmp *icp, const struct ip *ip)
2782 {
2783 	int mtu = ntohs(icp->icmp_nextmtu);
2784 
2785 	/* If no alternative MTU was proposed, try the next smaller one. */
2786 	if (!mtu)
2787 		mtu = ip_next_mtu(ntohs(ip->ip_len), 1);
2788 	if (mtu < V_tcp_minmss + sizeof(struct tcpiphdr))
2789 		mtu = V_tcp_minmss + sizeof(struct tcpiphdr);
2790 
2791 	return (mtu);
2792 }
2793 
2794 static void
2795 tcp_ctlinput_with_port(struct icmp *icp, uint16_t port)
2796 {
2797 	struct ip *ip;
2798 	struct tcphdr *th;
2799 	struct inpcb *inp;
2800 	struct tcpcb *tp;
2801 	struct inpcb *(*notify)(struct inpcb *, int);
2802 	struct in_conninfo inc;
2803 	tcp_seq icmp_tcp_seq;
2804 	int errno, mtu;
2805 
2806 	errno = icmp_errmap(icp);
2807 	switch (errno) {
2808 	case 0:
2809 		return;
2810 	case EMSGSIZE:
2811 		notify = tcp_mtudisc_notify;
2812 		break;
2813 	case ECONNREFUSED:
2814 		if (V_icmp_may_rst)
2815 			notify = tcp_drop_syn_sent;
2816 		else
2817 			notify = tcp_notify;
2818 		break;
2819 	case EHOSTUNREACH:
2820 		if (V_icmp_may_rst && icp->icmp_type == ICMP_TIMXCEED)
2821 			notify = tcp_drop_syn_sent;
2822 		else
2823 			notify = tcp_notify;
2824 		break;
2825 	default:
2826 		notify = tcp_notify;
2827 	}
2828 
2829 	ip = &icp->icmp_ip;
2830 	th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2));
2831 	icmp_tcp_seq = th->th_seq;
2832 	inp = in_pcblookup(&V_tcbinfo, ip->ip_dst, th->th_dport, ip->ip_src,
2833 	    th->th_sport, INPLOOKUP_WLOCKPCB, NULL);
2834 	if (inp != NULL)  {
2835 		tp = intotcpcb(inp);
2836 #ifdef TCP_OFFLOAD
2837 		if (tp->t_flags & TF_TOE && errno == EMSGSIZE) {
2838 			/*
2839 			 * MTU discovery for offloaded connections.  Let
2840 			 * the TOE driver verify seq# and process it.
2841 			 */
2842 			mtu = tcp_next_pmtu(icp, ip);
2843 			tcp_offload_pmtu_update(tp, icmp_tcp_seq, mtu);
2844 			goto out;
2845 		}
2846 #endif
2847 		if (tp->t_port != port)
2848 			goto out;
2849 		if (SEQ_GEQ(ntohl(icmp_tcp_seq), tp->snd_una) &&
2850 		    SEQ_LT(ntohl(icmp_tcp_seq), tp->snd_max)) {
2851 			if (errno == EMSGSIZE) {
2852 				/*
2853 				 * MTU discovery: we got a needfrag and
2854 				 * will potentially try a lower MTU.
2855 				 */
2856 				mtu = tcp_next_pmtu(icp, ip);
2857 
2858 				/*
2859 				 * Only process the offered MTU if it
2860 				 * is smaller than the current one.
2861 				 */
2862 				if (mtu < tp->t_maxseg +
2863 				    sizeof(struct tcpiphdr)) {
2864 					bzero(&inc, sizeof(inc));
2865 					inc.inc_faddr = ip->ip_dst;
2866 					inc.inc_fibnum =
2867 					    inp->inp_inc.inc_fibnum;
2868 					tcp_hc_updatemtu(&inc, mtu);
2869 					inp = tcp_mtudisc(inp, mtu);
2870 				}
2871 			} else
2872 				inp = (*notify)(inp, errno);
2873 		}
2874 	} else {
2875 		bzero(&inc, sizeof(inc));
2876 		inc.inc_fport = th->th_dport;
2877 		inc.inc_lport = th->th_sport;
2878 		inc.inc_faddr = ip->ip_dst;
2879 		inc.inc_laddr = ip->ip_src;
2880 		syncache_unreach(&inc, icmp_tcp_seq, port);
2881 	}
2882 out:
2883 	if (inp != NULL)
2884 		INP_WUNLOCK(inp);
2885 }
2886 
2887 static void
2888 tcp_ctlinput(struct icmp *icmp)
2889 {
2890 	tcp_ctlinput_with_port(icmp, htons(0));
2891 }
2892 
2893 static void
2894 tcp_ctlinput_viaudp(udp_tun_icmp_param_t param)
2895 {
2896 	/* Its a tunneled TCP over UDP icmp */
2897 	struct icmp *icmp = param.icmp;
2898 	struct ip *outer_ip, *inner_ip;
2899 	struct udphdr *udp;
2900 	struct tcphdr *th, ttemp;
2901 	int i_hlen, o_len;
2902 	uint16_t port;
2903 
2904 	outer_ip = (struct ip *)((caddr_t)icmp - sizeof(struct ip));
2905 	inner_ip = &icmp->icmp_ip;
2906 	i_hlen = inner_ip->ip_hl << 2;
2907 	o_len = ntohs(outer_ip->ip_len);
2908 	if (o_len <
2909 	    (sizeof(struct ip) + 8 + i_hlen + sizeof(struct udphdr) + offsetof(struct tcphdr, th_ack))) {
2910 		/* Not enough data present */
2911 		return;
2912 	}
2913 	/* Ok lets strip out the inner udphdr header by copying up on top of it the tcp hdr */
2914 	udp = (struct udphdr *)(((caddr_t)inner_ip) + i_hlen);
2915 	if (ntohs(udp->uh_sport) != V_tcp_udp_tunneling_port) {
2916 		return;
2917 	}
2918 	port = udp->uh_dport;
2919 	th = (struct tcphdr *)(udp + 1);
2920 	memcpy(&ttemp, th, sizeof(struct tcphdr));
2921 	memcpy(udp, &ttemp, sizeof(struct tcphdr));
2922 	/* Now adjust down the size of the outer IP header */
2923 	o_len -= sizeof(struct udphdr);
2924 	outer_ip->ip_len = htons(o_len);
2925 	/* Now call in to the normal handling code */
2926 	tcp_ctlinput_with_port(icmp, port);
2927 }
2928 #endif /* INET */
2929 
2930 #ifdef INET6
2931 static inline int
2932 tcp6_next_pmtu(const struct icmp6_hdr *icmp6)
2933 {
2934 	int mtu = ntohl(icmp6->icmp6_mtu);
2935 
2936 	/*
2937 	 * If no alternative MTU was proposed, or the proposed MTU was too
2938 	 * small, set to the min.
2939 	 */
2940 	if (mtu < IPV6_MMTU)
2941 		mtu = IPV6_MMTU - 8;	/* XXXNP: what is the adjustment for? */
2942 	return (mtu);
2943 }
2944 
2945 static void
2946 tcp6_ctlinput_with_port(struct ip6ctlparam *ip6cp, uint16_t port)
2947 {
2948 	struct in6_addr *dst;
2949 	struct inpcb *(*notify)(struct inpcb *, int);
2950 	struct ip6_hdr *ip6;
2951 	struct mbuf *m;
2952 	struct inpcb *inp;
2953 	struct tcpcb *tp;
2954 	struct icmp6_hdr *icmp6;
2955 	struct in_conninfo inc;
2956 	struct tcp_ports {
2957 		uint16_t th_sport;
2958 		uint16_t th_dport;
2959 	} t_ports;
2960 	tcp_seq icmp_tcp_seq;
2961 	unsigned int mtu;
2962 	unsigned int off;
2963 	int errno;
2964 
2965 	icmp6 = ip6cp->ip6c_icmp6;
2966 	m = ip6cp->ip6c_m;
2967 	ip6 = ip6cp->ip6c_ip6;
2968 	off = ip6cp->ip6c_off;
2969 	dst = &ip6cp->ip6c_finaldst->sin6_addr;
2970 
2971 	errno = icmp6_errmap(icmp6);
2972 	switch (errno) {
2973 	case 0:
2974 		return;
2975 	case EMSGSIZE:
2976 		notify = tcp_mtudisc_notify;
2977 		break;
2978 	case ECONNREFUSED:
2979 		if (V_icmp_may_rst)
2980 			notify = tcp_drop_syn_sent;
2981 		else
2982 			notify = tcp_notify;
2983 		break;
2984 	case EHOSTUNREACH:
2985 		/*
2986 		 * There are only four ICMPs that may reset connection:
2987 		 * - administratively prohibited
2988 		 * - port unreachable
2989 		 * - time exceeded in transit
2990 		 * - unknown next header
2991 		 */
2992 		if (V_icmp_may_rst &&
2993 		    ((icmp6->icmp6_type == ICMP6_DST_UNREACH &&
2994 		     (icmp6->icmp6_code == ICMP6_DST_UNREACH_ADMIN ||
2995 		      icmp6->icmp6_code == ICMP6_DST_UNREACH_NOPORT)) ||
2996 		    (icmp6->icmp6_type == ICMP6_TIME_EXCEEDED &&
2997 		      icmp6->icmp6_code == ICMP6_TIME_EXCEED_TRANSIT) ||
2998 		    (icmp6->icmp6_type == ICMP6_PARAM_PROB &&
2999 		      icmp6->icmp6_code == ICMP6_PARAMPROB_NEXTHEADER)))
3000 			notify = tcp_drop_syn_sent;
3001 		else
3002 			notify = tcp_notify;
3003 		break;
3004 	default:
3005 		notify = tcp_notify;
3006 	}
3007 
3008 	/* Check if we can safely get the ports from the tcp hdr */
3009 	if (m == NULL ||
3010 	    (m->m_pkthdr.len <
3011 		(int32_t) (off + sizeof(struct tcp_ports)))) {
3012 		return;
3013 	}
3014 	bzero(&t_ports, sizeof(struct tcp_ports));
3015 	m_copydata(m, off, sizeof(struct tcp_ports), (caddr_t)&t_ports);
3016 	inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_dst, t_ports.th_dport,
3017 	    &ip6->ip6_src, t_ports.th_sport, INPLOOKUP_WLOCKPCB, NULL);
3018 	off += sizeof(struct tcp_ports);
3019 	if (m->m_pkthdr.len < (int32_t) (off + sizeof(tcp_seq))) {
3020 		goto out;
3021 	}
3022 	m_copydata(m, off, sizeof(tcp_seq), (caddr_t)&icmp_tcp_seq);
3023 	if (inp != NULL)  {
3024 		tp = intotcpcb(inp);
3025 #ifdef TCP_OFFLOAD
3026 		if (tp->t_flags & TF_TOE && errno == EMSGSIZE) {
3027 			/* MTU discovery for offloaded connections. */
3028 			mtu = tcp6_next_pmtu(icmp6);
3029 			tcp_offload_pmtu_update(tp, icmp_tcp_seq, mtu);
3030 			goto out;
3031 		}
3032 #endif
3033 		if (tp->t_port != port)
3034 			goto out;
3035 		if (SEQ_GEQ(ntohl(icmp_tcp_seq), tp->snd_una) &&
3036 		    SEQ_LT(ntohl(icmp_tcp_seq), tp->snd_max)) {
3037 			if (errno == EMSGSIZE) {
3038 				/*
3039 				 * MTU discovery:
3040 				 * If we got a needfrag set the MTU
3041 				 * in the route to the suggested new
3042 				 * value (if given) and then notify.
3043 				 */
3044 				mtu = tcp6_next_pmtu(icmp6);
3045 
3046 				bzero(&inc, sizeof(inc));
3047 				inc.inc_fibnum = M_GETFIB(m);
3048 				inc.inc_flags |= INC_ISIPV6;
3049 				inc.inc6_faddr = *dst;
3050 				if (in6_setscope(&inc.inc6_faddr,
3051 					m->m_pkthdr.rcvif, NULL))
3052 					goto out;
3053 				/*
3054 				 * Only process the offered MTU if it
3055 				 * is smaller than the current one.
3056 				 */
3057 				if (mtu < tp->t_maxseg +
3058 				    sizeof (struct tcphdr) +
3059 				    sizeof (struct ip6_hdr)) {
3060 					tcp_hc_updatemtu(&inc, mtu);
3061 					tcp_mtudisc(inp, mtu);
3062 					ICMP6STAT_INC(icp6s_pmtuchg);
3063 				}
3064 			} else
3065 				inp = (*notify)(inp, errno);
3066 		}
3067 	} else {
3068 		bzero(&inc, sizeof(inc));
3069 		inc.inc_fibnum = M_GETFIB(m);
3070 		inc.inc_flags |= INC_ISIPV6;
3071 		inc.inc_fport = t_ports.th_dport;
3072 		inc.inc_lport = t_ports.th_sport;
3073 		inc.inc6_faddr = *dst;
3074 		inc.inc6_laddr = ip6->ip6_src;
3075 		syncache_unreach(&inc, icmp_tcp_seq, port);
3076 	}
3077 out:
3078 	if (inp != NULL)
3079 		INP_WUNLOCK(inp);
3080 }
3081 
3082 static void
3083 tcp6_ctlinput(struct ip6ctlparam *ctl)
3084 {
3085 	tcp6_ctlinput_with_port(ctl, htons(0));
3086 }
3087 
3088 static void
3089 tcp6_ctlinput_viaudp(udp_tun_icmp_param_t param)
3090 {
3091 	struct ip6ctlparam *ip6cp = param.ip6cp;
3092 	struct mbuf *m;
3093 	struct udphdr *udp;
3094 	uint16_t port;
3095 
3096 	m = m_pulldown(ip6cp->ip6c_m, ip6cp->ip6c_off, sizeof(struct udphdr), NULL);
3097 	if (m == NULL) {
3098 		return;
3099 	}
3100 	udp = mtod(m, struct udphdr *);
3101 	if (ntohs(udp->uh_sport) != V_tcp_udp_tunneling_port) {
3102 		return;
3103 	}
3104 	port = udp->uh_dport;
3105 	m_adj(m, sizeof(struct udphdr));
3106 	if ((m->m_flags & M_PKTHDR) == 0) {
3107 		ip6cp->ip6c_m->m_pkthdr.len -= sizeof(struct udphdr);
3108 	}
3109 	/* Now call in to the normal handling code */
3110 	tcp6_ctlinput_with_port(ip6cp, port);
3111 }
3112 
3113 #endif /* INET6 */
3114 
3115 static uint32_t
3116 tcp_keyed_hash(struct in_conninfo *inc, u_char *key, u_int len)
3117 {
3118 	SIPHASH_CTX ctx;
3119 	uint32_t hash[2];
3120 
3121 	KASSERT(len >= SIPHASH_KEY_LENGTH,
3122 	    ("%s: keylen %u too short ", __func__, len));
3123 	SipHash24_Init(&ctx);
3124 	SipHash_SetKey(&ctx, (uint8_t *)key);
3125 	SipHash_Update(&ctx, &inc->inc_fport, sizeof(uint16_t));
3126 	SipHash_Update(&ctx, &inc->inc_lport, sizeof(uint16_t));
3127 	switch (inc->inc_flags & INC_ISIPV6) {
3128 #ifdef INET
3129 	case 0:
3130 		SipHash_Update(&ctx, &inc->inc_faddr, sizeof(struct in_addr));
3131 		SipHash_Update(&ctx, &inc->inc_laddr, sizeof(struct in_addr));
3132 		break;
3133 #endif
3134 #ifdef INET6
3135 	case INC_ISIPV6:
3136 		SipHash_Update(&ctx, &inc->inc6_faddr, sizeof(struct in6_addr));
3137 		SipHash_Update(&ctx, &inc->inc6_laddr, sizeof(struct in6_addr));
3138 		break;
3139 #endif
3140 	}
3141 	SipHash_Final((uint8_t *)hash, &ctx);
3142 
3143 	return (hash[0] ^ hash[1]);
3144 }
3145 
3146 uint32_t
3147 tcp_new_ts_offset(struct in_conninfo *inc)
3148 {
3149 	struct in_conninfo inc_store, *local_inc;
3150 
3151 	if (!V_tcp_ts_offset_per_conn) {
3152 		memcpy(&inc_store, inc, sizeof(struct in_conninfo));
3153 		inc_store.inc_lport = 0;
3154 		inc_store.inc_fport = 0;
3155 		local_inc = &inc_store;
3156 	} else {
3157 		local_inc = inc;
3158 	}
3159 	return (tcp_keyed_hash(local_inc, V_ts_offset_secret,
3160 	    sizeof(V_ts_offset_secret)));
3161 }
3162 
3163 /*
3164  * Following is where TCP initial sequence number generation occurs.
3165  *
3166  * There are two places where we must use initial sequence numbers:
3167  * 1.  In SYN-ACK packets.
3168  * 2.  In SYN packets.
3169  *
3170  * All ISNs for SYN-ACK packets are generated by the syncache.  See
3171  * tcp_syncache.c for details.
3172  *
3173  * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
3174  * depends on this property.  In addition, these ISNs should be
3175  * unguessable so as to prevent connection hijacking.  To satisfy
3176  * the requirements of this situation, the algorithm outlined in
3177  * RFC 1948 is used, with only small modifications.
3178  *
3179  * Implementation details:
3180  *
3181  * Time is based off the system timer, and is corrected so that it
3182  * increases by one megabyte per second.  This allows for proper
3183  * recycling on high speed LANs while still leaving over an hour
3184  * before rollover.
3185  *
3186  * As reading the *exact* system time is too expensive to be done
3187  * whenever setting up a TCP connection, we increment the time
3188  * offset in two ways.  First, a small random positive increment
3189  * is added to isn_offset for each connection that is set up.
3190  * Second, the function tcp_isn_tick fires once per clock tick
3191  * and increments isn_offset as necessary so that sequence numbers
3192  * are incremented at approximately ISN_BYTES_PER_SECOND.  The
3193  * random positive increments serve only to ensure that the same
3194  * exact sequence number is never sent out twice (as could otherwise
3195  * happen when a port is recycled in less than the system tick
3196  * interval.)
3197  *
3198  * net.inet.tcp.isn_reseed_interval controls the number of seconds
3199  * between seeding of isn_secret.  This is normally set to zero,
3200  * as reseeding should not be necessary.
3201  *
3202  * Locking of the global variables isn_secret, isn_last_reseed, isn_offset,
3203  * isn_offset_old, and isn_ctx is performed using the ISN lock.  In
3204  * general, this means holding an exclusive (write) lock.
3205  */
3206 
3207 #define ISN_BYTES_PER_SECOND 1048576
3208 #define ISN_STATIC_INCREMENT 4096
3209 #define ISN_RANDOM_INCREMENT (4096 - 1)
3210 #define ISN_SECRET_LENGTH    SIPHASH_KEY_LENGTH
3211 
3212 VNET_DEFINE_STATIC(u_char, isn_secret[ISN_SECRET_LENGTH]);
3213 VNET_DEFINE_STATIC(int, isn_last);
3214 VNET_DEFINE_STATIC(int, isn_last_reseed);
3215 VNET_DEFINE_STATIC(u_int32_t, isn_offset);
3216 VNET_DEFINE_STATIC(u_int32_t, isn_offset_old);
3217 
3218 #define	V_isn_secret			VNET(isn_secret)
3219 #define	V_isn_last			VNET(isn_last)
3220 #define	V_isn_last_reseed		VNET(isn_last_reseed)
3221 #define	V_isn_offset			VNET(isn_offset)
3222 #define	V_isn_offset_old		VNET(isn_offset_old)
3223 
3224 tcp_seq
3225 tcp_new_isn(struct in_conninfo *inc)
3226 {
3227 	tcp_seq new_isn;
3228 	u_int32_t projected_offset;
3229 
3230 	ISN_LOCK();
3231 	/* Seed if this is the first use, reseed if requested. */
3232 	if ((V_isn_last_reseed == 0) || ((V_tcp_isn_reseed_interval > 0) &&
3233 	     (((u_int)V_isn_last_reseed + (u_int)V_tcp_isn_reseed_interval*hz)
3234 		< (u_int)ticks))) {
3235 		arc4rand(&V_isn_secret, sizeof(V_isn_secret), 0);
3236 		V_isn_last_reseed = ticks;
3237 	}
3238 
3239 	/* Compute the hash and return the ISN. */
3240 	new_isn = (tcp_seq)tcp_keyed_hash(inc, V_isn_secret,
3241 	    sizeof(V_isn_secret));
3242 	V_isn_offset += ISN_STATIC_INCREMENT +
3243 		(arc4random() & ISN_RANDOM_INCREMENT);
3244 	if (ticks != V_isn_last) {
3245 		projected_offset = V_isn_offset_old +
3246 		    ISN_BYTES_PER_SECOND / hz * (ticks - V_isn_last);
3247 		if (SEQ_GT(projected_offset, V_isn_offset))
3248 			V_isn_offset = projected_offset;
3249 		V_isn_offset_old = V_isn_offset;
3250 		V_isn_last = ticks;
3251 	}
3252 	new_isn += V_isn_offset;
3253 	ISN_UNLOCK();
3254 	return (new_isn);
3255 }
3256 
3257 /*
3258  * When a specific ICMP unreachable message is received and the
3259  * connection state is SYN-SENT, drop the connection.  This behavior
3260  * is controlled by the icmp_may_rst sysctl.
3261  */
3262 static struct inpcb *
3263 tcp_drop_syn_sent(struct inpcb *inp, int errno)
3264 {
3265 	struct tcpcb *tp;
3266 
3267 	NET_EPOCH_ASSERT();
3268 	INP_WLOCK_ASSERT(inp);
3269 
3270 	tp = intotcpcb(inp);
3271 	if (tp->t_state != TCPS_SYN_SENT)
3272 		return (inp);
3273 
3274 	if (IS_FASTOPEN(tp->t_flags))
3275 		tcp_fastopen_disable_path(tp);
3276 
3277 	tp = tcp_drop(tp, errno);
3278 	if (tp != NULL)
3279 		return (inp);
3280 	else
3281 		return (NULL);
3282 }
3283 
3284 /*
3285  * When `need fragmentation' ICMP is received, update our idea of the MSS
3286  * based on the new value. Also nudge TCP to send something, since we
3287  * know the packet we just sent was dropped.
3288  * This duplicates some code in the tcp_mss() function in tcp_input.c.
3289  */
3290 static struct inpcb *
3291 tcp_mtudisc_notify(struct inpcb *inp, int error)
3292 {
3293 
3294 	return (tcp_mtudisc(inp, -1));
3295 }
3296 
3297 static struct inpcb *
3298 tcp_mtudisc(struct inpcb *inp, int mtuoffer)
3299 {
3300 	struct tcpcb *tp;
3301 	struct socket *so;
3302 
3303 	INP_WLOCK_ASSERT(inp);
3304 
3305 	tp = intotcpcb(inp);
3306 	KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
3307 
3308 	tcp_mss_update(tp, -1, mtuoffer, NULL, NULL);
3309 
3310 	so = inp->inp_socket;
3311 	SOCKBUF_LOCK(&so->so_snd);
3312 	/* If the mss is larger than the socket buffer, decrease the mss. */
3313 	if (so->so_snd.sb_hiwat < tp->t_maxseg)
3314 		tp->t_maxseg = so->so_snd.sb_hiwat;
3315 	SOCKBUF_UNLOCK(&so->so_snd);
3316 
3317 	TCPSTAT_INC(tcps_mturesent);
3318 	tp->t_rtttime = 0;
3319 	tp->snd_nxt = tp->snd_una;
3320 	tcp_free_sackholes(tp);
3321 	tp->snd_recover = tp->snd_max;
3322 	if (tp->t_flags & TF_SACK_PERMIT)
3323 		EXIT_FASTRECOVERY(tp->t_flags);
3324 	if (tp->t_fb->tfb_tcp_mtu_chg != NULL) {
3325 		/*
3326 		 * Conceptually the snd_nxt setting
3327 		 * and freeing sack holes should
3328 		 * be done by the default stacks
3329 		 * own tfb_tcp_mtu_chg().
3330 		 */
3331 		tp->t_fb->tfb_tcp_mtu_chg(tp);
3332 	}
3333 	if (tcp_output(tp) < 0)
3334 		return (NULL);
3335 	else
3336 		return (inp);
3337 }
3338 
3339 #ifdef INET
3340 /*
3341  * Look-up the routing entry to the peer of this inpcb.  If no route
3342  * is found and it cannot be allocated, then return 0.  This routine
3343  * is called by TCP routines that access the rmx structure and by
3344  * tcp_mss_update to get the peer/interface MTU.
3345  */
3346 uint32_t
3347 tcp_maxmtu(struct in_conninfo *inc, struct tcp_ifcap *cap)
3348 {
3349 	struct nhop_object *nh;
3350 	struct ifnet *ifp;
3351 	uint32_t maxmtu = 0;
3352 
3353 	KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer"));
3354 
3355 	if (inc->inc_faddr.s_addr != INADDR_ANY) {
3356 		nh = fib4_lookup(inc->inc_fibnum, inc->inc_faddr, 0, NHR_NONE, 0);
3357 		if (nh == NULL)
3358 			return (0);
3359 
3360 		ifp = nh->nh_ifp;
3361 		maxmtu = nh->nh_mtu;
3362 
3363 		/* Report additional interface capabilities. */
3364 		if (cap != NULL) {
3365 			if (ifp->if_capenable & IFCAP_TSO4 &&
3366 			    ifp->if_hwassist & CSUM_TSO) {
3367 				cap->ifcap |= CSUM_TSO;
3368 				cap->tsomax = ifp->if_hw_tsomax;
3369 				cap->tsomaxsegcount = ifp->if_hw_tsomaxsegcount;
3370 				cap->tsomaxsegsize = ifp->if_hw_tsomaxsegsize;
3371 			}
3372 		}
3373 	}
3374 	return (maxmtu);
3375 }
3376 #endif /* INET */
3377 
3378 #ifdef INET6
3379 uint32_t
3380 tcp_maxmtu6(struct in_conninfo *inc, struct tcp_ifcap *cap)
3381 {
3382 	struct nhop_object *nh;
3383 	struct in6_addr dst6;
3384 	uint32_t scopeid;
3385 	struct ifnet *ifp;
3386 	uint32_t maxmtu = 0;
3387 
3388 	KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer"));
3389 
3390 	if (inc->inc_flags & INC_IPV6MINMTU)
3391 		return (IPV6_MMTU);
3392 
3393 	if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
3394 		in6_splitscope(&inc->inc6_faddr, &dst6, &scopeid);
3395 		nh = fib6_lookup(inc->inc_fibnum, &dst6, scopeid, NHR_NONE, 0);
3396 		if (nh == NULL)
3397 			return (0);
3398 
3399 		ifp = nh->nh_ifp;
3400 		maxmtu = nh->nh_mtu;
3401 
3402 		/* Report additional interface capabilities. */
3403 		if (cap != NULL) {
3404 			if (ifp->if_capenable & IFCAP_TSO6 &&
3405 			    ifp->if_hwassist & CSUM_TSO) {
3406 				cap->ifcap |= CSUM_TSO;
3407 				cap->tsomax = ifp->if_hw_tsomax;
3408 				cap->tsomaxsegcount = ifp->if_hw_tsomaxsegcount;
3409 				cap->tsomaxsegsize = ifp->if_hw_tsomaxsegsize;
3410 			}
3411 		}
3412 	}
3413 
3414 	return (maxmtu);
3415 }
3416 
3417 /*
3418  * Handle setsockopt(IPV6_USE_MIN_MTU) by a TCP stack.
3419  *
3420  * XXXGL: we are updating inpcb here with INC_IPV6MINMTU flag.
3421  * The right place to do that is ip6_setpktopt() that has just been
3422  * executed.  By the way it just filled ip6po_minmtu for us.
3423  */
3424 void
3425 tcp6_use_min_mtu(struct tcpcb *tp)
3426 {
3427 	struct inpcb *inp = tptoinpcb(tp);
3428 
3429 	INP_WLOCK_ASSERT(inp);
3430 	/*
3431 	 * In case of the IPV6_USE_MIN_MTU socket
3432 	 * option, the INC_IPV6MINMTU flag to announce
3433 	 * a corresponding MSS during the initial
3434 	 * handshake.  If the TCP connection is not in
3435 	 * the front states, just reduce the MSS being
3436 	 * used.  This avoids the sending of TCP
3437 	 * segments which will be fragmented at the
3438 	 * IPv6 layer.
3439 	 */
3440 	inp->inp_inc.inc_flags |= INC_IPV6MINMTU;
3441 	if ((tp->t_state >= TCPS_SYN_SENT) &&
3442 	    (inp->inp_inc.inc_flags & INC_ISIPV6)) {
3443 		struct ip6_pktopts *opt;
3444 
3445 		opt = inp->in6p_outputopts;
3446 		if (opt != NULL && opt->ip6po_minmtu == IP6PO_MINMTU_ALL &&
3447 		    tp->t_maxseg > TCP6_MSS)
3448 			tp->t_maxseg = TCP6_MSS;
3449 	}
3450 }
3451 #endif /* INET6 */
3452 
3453 /*
3454  * Calculate effective SMSS per RFC5681 definition for a given TCP
3455  * connection at its current state, taking into account SACK and etc.
3456  */
3457 u_int
3458 tcp_maxseg(const struct tcpcb *tp)
3459 {
3460 	u_int optlen;
3461 
3462 	if (tp->t_flags & TF_NOOPT)
3463 		return (tp->t_maxseg);
3464 
3465 	/*
3466 	 * Here we have a simplified code from tcp_addoptions(),
3467 	 * without a proper loop, and having most of paddings hardcoded.
3468 	 * We might make mistakes with padding here in some edge cases,
3469 	 * but this is harmless, since result of tcp_maxseg() is used
3470 	 * only in cwnd and ssthresh estimations.
3471 	 */
3472 	if (TCPS_HAVEESTABLISHED(tp->t_state)) {
3473 		if (tp->t_flags & TF_RCVD_TSTMP)
3474 			optlen = TCPOLEN_TSTAMP_APPA;
3475 		else
3476 			optlen = 0;
3477 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
3478 		if (tp->t_flags & TF_SIGNATURE)
3479 			optlen += PADTCPOLEN(TCPOLEN_SIGNATURE);
3480 #endif
3481 		if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks > 0) {
3482 			optlen += TCPOLEN_SACKHDR;
3483 			optlen += tp->rcv_numsacks * TCPOLEN_SACK;
3484 			optlen = PADTCPOLEN(optlen);
3485 		}
3486 	} else {
3487 		if (tp->t_flags & TF_REQ_TSTMP)
3488 			optlen = TCPOLEN_TSTAMP_APPA;
3489 		else
3490 			optlen = PADTCPOLEN(TCPOLEN_MAXSEG);
3491 		if (tp->t_flags & TF_REQ_SCALE)
3492 			optlen += PADTCPOLEN(TCPOLEN_WINDOW);
3493 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
3494 		if (tp->t_flags & TF_SIGNATURE)
3495 			optlen += PADTCPOLEN(TCPOLEN_SIGNATURE);
3496 #endif
3497 		if (tp->t_flags & TF_SACK_PERMIT)
3498 			optlen += PADTCPOLEN(TCPOLEN_SACK_PERMITTED);
3499 	}
3500 #undef PAD
3501 	optlen = min(optlen, TCP_MAXOLEN);
3502 	return (tp->t_maxseg - optlen);
3503 }
3504 
3505 
3506 u_int
3507 tcp_fixed_maxseg(const struct tcpcb *tp)
3508 {
3509 	int optlen;
3510 
3511 	if (tp->t_flags & TF_NOOPT)
3512 		return (tp->t_maxseg);
3513 
3514 	/*
3515 	 * Here we have a simplified code from tcp_addoptions(),
3516 	 * without a proper loop, and having most of paddings hardcoded.
3517 	 * We only consider fixed options that we would send every
3518 	 * time I.e. SACK is not considered. This is important
3519 	 * for cc modules to figure out what the modulo of the
3520 	 * cwnd should be.
3521 	 */
3522 #define	PAD(len)	((((len) / 4) + !!((len) % 4)) * 4)
3523 	if (TCPS_HAVEESTABLISHED(tp->t_state)) {
3524 		if (tp->t_flags & TF_RCVD_TSTMP)
3525 			optlen = TCPOLEN_TSTAMP_APPA;
3526 		else
3527 			optlen = 0;
3528 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
3529 		if (tp->t_flags & TF_SIGNATURE)
3530 			optlen += PAD(TCPOLEN_SIGNATURE);
3531 #endif
3532 	} else {
3533 		if (tp->t_flags & TF_REQ_TSTMP)
3534 			optlen = TCPOLEN_TSTAMP_APPA;
3535 		else
3536 			optlen = PAD(TCPOLEN_MAXSEG);
3537 		if (tp->t_flags & TF_REQ_SCALE)
3538 			optlen += PAD(TCPOLEN_WINDOW);
3539 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
3540 		if (tp->t_flags & TF_SIGNATURE)
3541 			optlen += PAD(TCPOLEN_SIGNATURE);
3542 #endif
3543 		if (tp->t_flags & TF_SACK_PERMIT)
3544 			optlen += PAD(TCPOLEN_SACK_PERMITTED);
3545 	}
3546 #undef PAD
3547 	optlen = min(optlen, TCP_MAXOLEN);
3548 	return (tp->t_maxseg - optlen);
3549 }
3550 
3551 
3552 
3553 static int
3554 sysctl_drop(SYSCTL_HANDLER_ARGS)
3555 {
3556 	/* addrs[0] is a foreign socket, addrs[1] is a local one. */
3557 	struct sockaddr_storage addrs[2];
3558 	struct inpcb *inp;
3559 	struct tcpcb *tp;
3560 #ifdef INET
3561 	struct sockaddr_in *fin = NULL, *lin = NULL;
3562 #endif
3563 	struct epoch_tracker et;
3564 #ifdef INET6
3565 	struct sockaddr_in6 *fin6, *lin6;
3566 #endif
3567 	int error;
3568 
3569 	inp = NULL;
3570 #ifdef INET6
3571 	fin6 = lin6 = NULL;
3572 #endif
3573 	error = 0;
3574 
3575 	if (req->oldptr != NULL || req->oldlen != 0)
3576 		return (EINVAL);
3577 	if (req->newptr == NULL)
3578 		return (EPERM);
3579 	if (req->newlen < sizeof(addrs))
3580 		return (ENOMEM);
3581 	error = SYSCTL_IN(req, &addrs, sizeof(addrs));
3582 	if (error)
3583 		return (error);
3584 
3585 	switch (addrs[0].ss_family) {
3586 #ifdef INET6
3587 	case AF_INET6:
3588 		fin6 = (struct sockaddr_in6 *)&addrs[0];
3589 		lin6 = (struct sockaddr_in6 *)&addrs[1];
3590 		if (fin6->sin6_len != sizeof(struct sockaddr_in6) ||
3591 		    lin6->sin6_len != sizeof(struct sockaddr_in6))
3592 			return (EINVAL);
3593 		if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) {
3594 			if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr))
3595 				return (EINVAL);
3596 			in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]);
3597 			in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]);
3598 #ifdef INET
3599 			fin = (struct sockaddr_in *)&addrs[0];
3600 			lin = (struct sockaddr_in *)&addrs[1];
3601 #endif
3602 			break;
3603 		}
3604 		error = sa6_embedscope(fin6, V_ip6_use_defzone);
3605 		if (error)
3606 			return (error);
3607 		error = sa6_embedscope(lin6, V_ip6_use_defzone);
3608 		if (error)
3609 			return (error);
3610 		break;
3611 #endif
3612 #ifdef INET
3613 	case AF_INET:
3614 		fin = (struct sockaddr_in *)&addrs[0];
3615 		lin = (struct sockaddr_in *)&addrs[1];
3616 		if (fin->sin_len != sizeof(struct sockaddr_in) ||
3617 		    lin->sin_len != sizeof(struct sockaddr_in))
3618 			return (EINVAL);
3619 		break;
3620 #endif
3621 	default:
3622 		return (EINVAL);
3623 	}
3624 	NET_EPOCH_ENTER(et);
3625 	switch (addrs[0].ss_family) {
3626 #ifdef INET6
3627 	case AF_INET6:
3628 		inp = in6_pcblookup(&V_tcbinfo, &fin6->sin6_addr,
3629 		    fin6->sin6_port, &lin6->sin6_addr, lin6->sin6_port,
3630 		    INPLOOKUP_WLOCKPCB, NULL);
3631 		break;
3632 #endif
3633 #ifdef INET
3634 	case AF_INET:
3635 		inp = in_pcblookup(&V_tcbinfo, fin->sin_addr, fin->sin_port,
3636 		    lin->sin_addr, lin->sin_port, INPLOOKUP_WLOCKPCB, NULL);
3637 		break;
3638 #endif
3639 	}
3640 	if (inp != NULL) {
3641 		if (!SOLISTENING(inp->inp_socket)) {
3642 			tp = intotcpcb(inp);
3643 			tp = tcp_drop(tp, ECONNABORTED);
3644 			if (tp != NULL)
3645 				INP_WUNLOCK(inp);
3646 		} else
3647 			INP_WUNLOCK(inp);
3648 	} else
3649 		error = ESRCH;
3650 	NET_EPOCH_EXIT(et);
3651 	return (error);
3652 }
3653 
3654 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop,
3655     CTLFLAG_VNET | CTLTYPE_STRUCT | CTLFLAG_WR | CTLFLAG_SKIP |
3656     CTLFLAG_NEEDGIANT, NULL, 0, sysctl_drop, "",
3657     "Drop TCP connection");
3658 
3659 static int
3660 tcp_sysctl_setsockopt(SYSCTL_HANDLER_ARGS)
3661 {
3662 	return (sysctl_setsockopt(oidp, arg1, arg2, req, &V_tcbinfo,
3663 	    &tcp_ctloutput_set));
3664 }
3665 
3666 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, setsockopt,
3667     CTLFLAG_VNET | CTLTYPE_STRUCT | CTLFLAG_WR | CTLFLAG_SKIP |
3668     CTLFLAG_MPSAFE, NULL, 0, tcp_sysctl_setsockopt, "",
3669     "Set socket option for TCP endpoint");
3670 
3671 #ifdef KERN_TLS
3672 static int
3673 sysctl_switch_tls(SYSCTL_HANDLER_ARGS)
3674 {
3675 	/* addrs[0] is a foreign socket, addrs[1] is a local one. */
3676 	struct sockaddr_storage addrs[2];
3677 	struct inpcb *inp;
3678 #ifdef INET
3679 	struct sockaddr_in *fin = NULL, *lin = NULL;
3680 #endif
3681 	struct epoch_tracker et;
3682 #ifdef INET6
3683 	struct sockaddr_in6 *fin6, *lin6;
3684 #endif
3685 	int error;
3686 
3687 	inp = NULL;
3688 #ifdef INET6
3689 	fin6 = lin6 = NULL;
3690 #endif
3691 	error = 0;
3692 
3693 	if (req->oldptr != NULL || req->oldlen != 0)
3694 		return (EINVAL);
3695 	if (req->newptr == NULL)
3696 		return (EPERM);
3697 	if (req->newlen < sizeof(addrs))
3698 		return (ENOMEM);
3699 	error = SYSCTL_IN(req, &addrs, sizeof(addrs));
3700 	if (error)
3701 		return (error);
3702 
3703 	switch (addrs[0].ss_family) {
3704 #ifdef INET6
3705 	case AF_INET6:
3706 		fin6 = (struct sockaddr_in6 *)&addrs[0];
3707 		lin6 = (struct sockaddr_in6 *)&addrs[1];
3708 		if (fin6->sin6_len != sizeof(struct sockaddr_in6) ||
3709 		    lin6->sin6_len != sizeof(struct sockaddr_in6))
3710 			return (EINVAL);
3711 		if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) {
3712 			if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr))
3713 				return (EINVAL);
3714 			in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]);
3715 			in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]);
3716 #ifdef INET
3717 			fin = (struct sockaddr_in *)&addrs[0];
3718 			lin = (struct sockaddr_in *)&addrs[1];
3719 #endif
3720 			break;
3721 		}
3722 		error = sa6_embedscope(fin6, V_ip6_use_defzone);
3723 		if (error)
3724 			return (error);
3725 		error = sa6_embedscope(lin6, V_ip6_use_defzone);
3726 		if (error)
3727 			return (error);
3728 		break;
3729 #endif
3730 #ifdef INET
3731 	case AF_INET:
3732 		fin = (struct sockaddr_in *)&addrs[0];
3733 		lin = (struct sockaddr_in *)&addrs[1];
3734 		if (fin->sin_len != sizeof(struct sockaddr_in) ||
3735 		    lin->sin_len != sizeof(struct sockaddr_in))
3736 			return (EINVAL);
3737 		break;
3738 #endif
3739 	default:
3740 		return (EINVAL);
3741 	}
3742 	NET_EPOCH_ENTER(et);
3743 	switch (addrs[0].ss_family) {
3744 #ifdef INET6
3745 	case AF_INET6:
3746 		inp = in6_pcblookup(&V_tcbinfo, &fin6->sin6_addr,
3747 		    fin6->sin6_port, &lin6->sin6_addr, lin6->sin6_port,
3748 		    INPLOOKUP_WLOCKPCB, NULL);
3749 		break;
3750 #endif
3751 #ifdef INET
3752 	case AF_INET:
3753 		inp = in_pcblookup(&V_tcbinfo, fin->sin_addr, fin->sin_port,
3754 		    lin->sin_addr, lin->sin_port, INPLOOKUP_WLOCKPCB, NULL);
3755 		break;
3756 #endif
3757 	}
3758 	NET_EPOCH_EXIT(et);
3759 	if (inp != NULL) {
3760 		struct socket *so;
3761 
3762 		so = inp->inp_socket;
3763 		soref(so);
3764 		error = ktls_set_tx_mode(so,
3765 		    arg2 == 0 ? TCP_TLS_MODE_SW : TCP_TLS_MODE_IFNET);
3766 		INP_WUNLOCK(inp);
3767 		sorele(so);
3768 	} else
3769 		error = ESRCH;
3770 	return (error);
3771 }
3772 
3773 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, switch_to_sw_tls,
3774     CTLFLAG_VNET | CTLTYPE_STRUCT | CTLFLAG_WR | CTLFLAG_SKIP |
3775     CTLFLAG_NEEDGIANT, NULL, 0, sysctl_switch_tls, "",
3776     "Switch TCP connection to SW TLS");
3777 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, switch_to_ifnet_tls,
3778     CTLFLAG_VNET | CTLTYPE_STRUCT | CTLFLAG_WR | CTLFLAG_SKIP |
3779     CTLFLAG_NEEDGIANT, NULL, 1, sysctl_switch_tls, "",
3780     "Switch TCP connection to ifnet TLS");
3781 #endif
3782 
3783 /*
3784  * Generate a standardized TCP log line for use throughout the
3785  * tcp subsystem.  Memory allocation is done with M_NOWAIT to
3786  * allow use in the interrupt context.
3787  *
3788  * NB: The caller MUST free(s, M_TCPLOG) the returned string.
3789  * NB: The function may return NULL if memory allocation failed.
3790  *
3791  * Due to header inclusion and ordering limitations the struct ip
3792  * and ip6_hdr pointers have to be passed as void pointers.
3793  */
3794 char *
3795 tcp_log_vain(struct in_conninfo *inc, struct tcphdr *th, const void *ip4hdr,
3796     const void *ip6hdr)
3797 {
3798 
3799 	/* Is logging enabled? */
3800 	if (V_tcp_log_in_vain == 0)
3801 		return (NULL);
3802 
3803 	return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
3804 }
3805 
3806 char *
3807 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, const void *ip4hdr,
3808     const void *ip6hdr)
3809 {
3810 
3811 	/* Is logging enabled? */
3812 	if (tcp_log_debug == 0)
3813 		return (NULL);
3814 
3815 	return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
3816 }
3817 
3818 static char *
3819 tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th, const void *ip4hdr,
3820     const void *ip6hdr)
3821 {
3822 	char *s, *sp;
3823 	size_t size;
3824 #ifdef INET
3825 	const struct ip *ip = (const struct ip *)ip4hdr;
3826 #endif
3827 #ifdef INET6
3828 	const struct ip6_hdr *ip6 = (const struct ip6_hdr *)ip6hdr;
3829 #endif /* INET6 */
3830 
3831 	/*
3832 	 * The log line looks like this:
3833 	 * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>"
3834 	 */
3835 	size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") +
3836 	    sizeof(PRINT_TH_FLAGS) + 1 +
3837 #ifdef INET6
3838 	    2 * INET6_ADDRSTRLEN;
3839 #else
3840 	    2 * INET_ADDRSTRLEN;
3841 #endif /* INET6 */
3842 
3843 	s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT);
3844 	if (s == NULL)
3845 		return (NULL);
3846 
3847 	strcat(s, "TCP: [");
3848 	sp = s + strlen(s);
3849 
3850 	if (inc && ((inc->inc_flags & INC_ISIPV6) == 0)) {
3851 		inet_ntoa_r(inc->inc_faddr, sp);
3852 		sp = s + strlen(s);
3853 		sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
3854 		sp = s + strlen(s);
3855 		inet_ntoa_r(inc->inc_laddr, sp);
3856 		sp = s + strlen(s);
3857 		sprintf(sp, "]:%i", ntohs(inc->inc_lport));
3858 #ifdef INET6
3859 	} else if (inc) {
3860 		ip6_sprintf(sp, &inc->inc6_faddr);
3861 		sp = s + strlen(s);
3862 		sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
3863 		sp = s + strlen(s);
3864 		ip6_sprintf(sp, &inc->inc6_laddr);
3865 		sp = s + strlen(s);
3866 		sprintf(sp, "]:%i", ntohs(inc->inc_lport));
3867 	} else if (ip6 && th) {
3868 		ip6_sprintf(sp, &ip6->ip6_src);
3869 		sp = s + strlen(s);
3870 		sprintf(sp, "]:%i to [", ntohs(th->th_sport));
3871 		sp = s + strlen(s);
3872 		ip6_sprintf(sp, &ip6->ip6_dst);
3873 		sp = s + strlen(s);
3874 		sprintf(sp, "]:%i", ntohs(th->th_dport));
3875 #endif /* INET6 */
3876 #ifdef INET
3877 	} else if (ip && th) {
3878 		inet_ntoa_r(ip->ip_src, sp);
3879 		sp = s + strlen(s);
3880 		sprintf(sp, "]:%i to [", ntohs(th->th_sport));
3881 		sp = s + strlen(s);
3882 		inet_ntoa_r(ip->ip_dst, sp);
3883 		sp = s + strlen(s);
3884 		sprintf(sp, "]:%i", ntohs(th->th_dport));
3885 #endif /* INET */
3886 	} else {
3887 		free(s, M_TCPLOG);
3888 		return (NULL);
3889 	}
3890 	sp = s + strlen(s);
3891 	if (th)
3892 		sprintf(sp, " tcpflags 0x%b", tcp_get_flags(th), PRINT_TH_FLAGS);
3893 	if (*(s + size - 1) != '\0')
3894 		panic("%s: string too long", __func__);
3895 	return (s);
3896 }
3897 
3898 /*
3899  * A subroutine which makes it easy to track TCP state changes with DTrace.
3900  * This function shouldn't be called for t_state initializations that don't
3901  * correspond to actual TCP state transitions.
3902  */
3903 void
3904 tcp_state_change(struct tcpcb *tp, int newstate)
3905 {
3906 #if defined(KDTRACE_HOOKS)
3907 	int pstate = tp->t_state;
3908 #endif
3909 
3910 	TCPSTATES_DEC(tp->t_state);
3911 	TCPSTATES_INC(newstate);
3912 	tp->t_state = newstate;
3913 	TCP_PROBE6(state__change, NULL, tp, NULL, tp, NULL, pstate);
3914 }
3915 
3916 /*
3917  * Create an external-format (``xtcpcb'') structure using the information in
3918  * the kernel-format tcpcb structure pointed to by tp.  This is done to
3919  * reduce the spew of irrelevant information over this interface, to isolate
3920  * user code from changes in the kernel structure, and potentially to provide
3921  * information-hiding if we decide that some of this information should be
3922  * hidden from users.
3923  */
3924 void
3925 tcp_inptoxtp(const struct inpcb *inp, struct xtcpcb *xt)
3926 {
3927 	struct tcpcb *tp = intotcpcb(inp);
3928 	sbintime_t now;
3929 
3930 	bzero(xt, sizeof(*xt));
3931 	xt->t_state = tp->t_state;
3932 	xt->t_logstate = tcp_get_bblog_state(tp);
3933 	xt->t_flags = tp->t_flags;
3934 	xt->t_sndzerowin = tp->t_sndzerowin;
3935 	xt->t_sndrexmitpack = tp->t_sndrexmitpack;
3936 	xt->t_rcvoopack = tp->t_rcvoopack;
3937 	xt->t_rcv_wnd = tp->rcv_wnd;
3938 	xt->t_snd_wnd = tp->snd_wnd;
3939 	xt->t_snd_cwnd = tp->snd_cwnd;
3940 	xt->t_snd_ssthresh = tp->snd_ssthresh;
3941 	xt->t_dsack_bytes = tp->t_dsack_bytes;
3942 	xt->t_dsack_tlp_bytes = tp->t_dsack_tlp_bytes;
3943 	xt->t_dsack_pack = tp->t_dsack_pack;
3944 	xt->t_maxseg = tp->t_maxseg;
3945 	xt->xt_ecn = (tp->t_flags2 & TF2_ECN_PERMIT) ? 1 : 0 +
3946 		     (tp->t_flags2 & TF2_ACE_PERMIT) ? 2 : 0;
3947 
3948 	now = getsbinuptime();
3949 #define	COPYTIMER(which,where)	do {					\
3950 	if (tp->t_timers[which] != SBT_MAX)				\
3951 		xt->where = (tp->t_timers[which] - now) / SBT_1MS;	\
3952 	else								\
3953 		xt->where = 0;						\
3954 } while (0)
3955 	COPYTIMER(TT_DELACK, tt_delack);
3956 	COPYTIMER(TT_REXMT, tt_rexmt);
3957 	COPYTIMER(TT_PERSIST, tt_persist);
3958 	COPYTIMER(TT_KEEP, tt_keep);
3959 	COPYTIMER(TT_2MSL, tt_2msl);
3960 #undef COPYTIMER
3961 	xt->t_rcvtime = 1000 * (ticks - tp->t_rcvtime) / hz;
3962 
3963 	xt->xt_encaps_port = tp->t_port;
3964 	bcopy(tp->t_fb->tfb_tcp_block_name, xt->xt_stack,
3965 	    TCP_FUNCTION_NAME_LEN_MAX);
3966 	bcopy(CC_ALGO(tp)->name, xt->xt_cc, TCP_CA_NAME_MAX);
3967 #ifdef TCP_BLACKBOX
3968 	(void)tcp_log_get_id(tp, xt->xt_logid);
3969 #endif
3970 
3971 	xt->xt_len = sizeof(struct xtcpcb);
3972 	in_pcbtoxinpcb(inp, &xt->xt_inp);
3973 	/*
3974 	 * TCP doesn't use inp_ppcb pointer, we embed inpcb into tcpcb.
3975 	 * Fixup the pointer that in_pcbtoxinpcb() has set.  When printing
3976 	 * TCP netstat(1) used to use this pointer, so this fixup needs to
3977 	 * stay for stable/14.
3978 	 */
3979 	xt->xt_inp.inp_ppcb = (uintptr_t)tp;
3980 }
3981 
3982 void
3983 tcp_log_end_status(struct tcpcb *tp, uint8_t status)
3984 {
3985 	uint32_t bit, i;
3986 
3987 	if ((tp == NULL) ||
3988 	    (status > TCP_EI_STATUS_MAX_VALUE) ||
3989 	    (status == 0)) {
3990 		/* Invalid */
3991 		return;
3992 	}
3993 	if (status > (sizeof(uint32_t) * 8)) {
3994 		/* Should this be a KASSERT? */
3995 		return;
3996 	}
3997 	bit = 1U << (status - 1);
3998 	if (bit & tp->t_end_info_status) {
3999 		/* already logged */
4000 		return;
4001 	}
4002 	for (i = 0; i < TCP_END_BYTE_INFO; i++) {
4003 		if (tp->t_end_info_bytes[i] == TCP_EI_EMPTY_SLOT) {
4004 			tp->t_end_info_bytes[i] = status;
4005 			tp->t_end_info_status |= bit;
4006 			break;
4007 		}
4008 	}
4009 }
4010 
4011 int
4012 tcp_can_enable_pacing(void)
4013 {
4014 
4015 	if ((tcp_pacing_limit == -1) ||
4016 	    (tcp_pacing_limit > number_of_tcp_connections_pacing)) {
4017 		atomic_fetchadd_int(&number_of_tcp_connections_pacing, 1);
4018 		shadow_num_connections = number_of_tcp_connections_pacing;
4019 		return (1);
4020 	} else {
4021 		counter_u64_add(tcp_pacing_failures, 1);
4022 		return (0);
4023 	}
4024 }
4025 
4026 static uint8_t tcp_pacing_warning = 0;
4027 
4028 void
4029 tcp_decrement_paced_conn(void)
4030 {
4031 	uint32_t ret;
4032 
4033 	ret = atomic_fetchadd_int(&number_of_tcp_connections_pacing, -1);
4034 	shadow_num_connections = number_of_tcp_connections_pacing;
4035 	KASSERT(ret != 0, ("tcp_paced_connection_exits -1 would cause wrap?"));
4036 	if (ret == 0) {
4037 		if (tcp_pacing_limit != -1) {
4038 			printf("Warning all pacing is now disabled, count decrements invalidly!\n");
4039 			tcp_pacing_limit = 0;
4040 		} else if (tcp_pacing_warning == 0) {
4041 			printf("Warning pacing count is invalid, invalid decrement\n");
4042 			tcp_pacing_warning = 1;
4043 		}
4044 	}
4045 }
4046 
4047 static void
4048 tcp_default_switch_failed(struct tcpcb *tp)
4049 {
4050 	/*
4051 	 * If a switch fails we only need to
4052 	 * care about two things:
4053 	 * a) The t_flags2
4054 	 * and
4055 	 * b) The timer granularity.
4056 	 * Timeouts, at least for now, don't use the
4057 	 * old callout system in the other stacks so
4058 	 * those are hopefully safe.
4059 	 */
4060 	tcp_lro_features_off(tp);
4061 	tcp_change_time_units(tp, TCP_TMR_GRANULARITY_TICKS);
4062 }
4063 
4064 #ifdef TCP_ACCOUNTING
4065 int
4066 tcp_do_ack_accounting(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to, uint32_t tiwin, int mss)
4067 {
4068 	if (SEQ_LT(th->th_ack, tp->snd_una)) {
4069 		/* Do we have a SACK? */
4070 		if (to->to_flags & TOF_SACK) {
4071 			if (tp->t_flags2 & TF2_TCP_ACCOUNTING) {
4072 				tp->tcp_cnt_counters[ACK_SACK]++;
4073 			}
4074 			return (ACK_SACK);
4075 		} else {
4076 			if (tp->t_flags2 & TF2_TCP_ACCOUNTING) {
4077 				tp->tcp_cnt_counters[ACK_BEHIND]++;
4078 			}
4079 			return (ACK_BEHIND);
4080 		}
4081 	} else if (th->th_ack == tp->snd_una) {
4082 		/* Do we have a SACK? */
4083 		if (to->to_flags & TOF_SACK) {
4084 			if (tp->t_flags2 & TF2_TCP_ACCOUNTING) {
4085 				tp->tcp_cnt_counters[ACK_SACK]++;
4086 			}
4087 			return (ACK_SACK);
4088 		} else if (tiwin != tp->snd_wnd) {
4089 			if (tp->t_flags2 & TF2_TCP_ACCOUNTING) {
4090 				tp->tcp_cnt_counters[ACK_RWND]++;
4091 			}
4092 			return (ACK_RWND);
4093 		} else {
4094 			if (tp->t_flags2 & TF2_TCP_ACCOUNTING) {
4095 				tp->tcp_cnt_counters[ACK_DUPACK]++;
4096 			}
4097 			return (ACK_DUPACK);
4098 		}
4099 	} else {
4100 		if (!SEQ_GT(th->th_ack, tp->snd_max)) {
4101 			if (tp->t_flags2 & TF2_TCP_ACCOUNTING) {
4102 				tp->tcp_cnt_counters[CNT_OF_ACKS_IN] += (((th->th_ack - tp->snd_una) + mss - 1)/mss);
4103 			}
4104 		}
4105 		if (to->to_flags & TOF_SACK) {
4106 			if (tp->t_flags2 & TF2_TCP_ACCOUNTING) {
4107 				tp->tcp_cnt_counters[ACK_CUMACK_SACK]++;
4108 			}
4109 			return (ACK_CUMACK_SACK);
4110 		} else {
4111 			if (tp->t_flags2 & TF2_TCP_ACCOUNTING) {
4112 				tp->tcp_cnt_counters[ACK_CUMACK]++;
4113 			}
4114 			return (ACK_CUMACK);
4115 		}
4116 	}
4117 }
4118 #endif
4119 
4120 void
4121 tcp_change_time_units(struct tcpcb *tp, int granularity)
4122 {
4123 	if (tp->t_tmr_granularity == granularity) {
4124 		/* We are there */
4125 		return;
4126 	}
4127 	if (granularity == TCP_TMR_GRANULARITY_USEC) {
4128 		KASSERT((tp->t_tmr_granularity == TCP_TMR_GRANULARITY_TICKS),
4129 			("Granularity is not TICKS its %u in tp:%p",
4130 			 tp->t_tmr_granularity, tp));
4131 		tp->t_rttlow = TICKS_2_USEC(tp->t_rttlow);
4132 		if (tp->t_srtt > 1) {
4133 			uint32_t val, frac;
4134 
4135 			val = tp->t_srtt >> TCP_RTT_SHIFT;
4136 			frac = tp->t_srtt & 0x1f;
4137 			tp->t_srtt = TICKS_2_USEC(val);
4138 			/*
4139 			 * frac is the fractional part of the srtt (if any)
4140 			 * but its in ticks and every bit represents
4141 			 * 1/32nd of a hz.
4142 			 */
4143 			if (frac) {
4144 				if (hz == 1000) {
4145 					frac = (((uint64_t)frac * (uint64_t)HPTS_USEC_IN_MSEC) / (uint64_t)TCP_RTT_SCALE);
4146 				} else {
4147 					frac = (((uint64_t)frac * (uint64_t)HPTS_USEC_IN_SEC) / ((uint64_t)(hz) * (uint64_t)TCP_RTT_SCALE));
4148 				}
4149 				tp->t_srtt += frac;
4150 			}
4151 		}
4152 		if (tp->t_rttvar) {
4153 			uint32_t val, frac;
4154 
4155 			val = tp->t_rttvar >> TCP_RTTVAR_SHIFT;
4156 			frac = tp->t_rttvar & 0x1f;
4157 			tp->t_rttvar = TICKS_2_USEC(val);
4158 			/*
4159 			 * frac is the fractional part of the srtt (if any)
4160 			 * but its in ticks and every bit represents
4161 			 * 1/32nd of a hz.
4162 			 */
4163 			if (frac) {
4164 				if (hz == 1000) {
4165 					frac = (((uint64_t)frac * (uint64_t)HPTS_USEC_IN_MSEC) / (uint64_t)TCP_RTT_SCALE);
4166 				} else {
4167 					frac = (((uint64_t)frac * (uint64_t)HPTS_USEC_IN_SEC) / ((uint64_t)(hz) * (uint64_t)TCP_RTT_SCALE));
4168 				}
4169 				tp->t_rttvar += frac;
4170 			}
4171 		}
4172 		tp->t_tmr_granularity = TCP_TMR_GRANULARITY_USEC;
4173 	} else if (granularity == TCP_TMR_GRANULARITY_TICKS) {
4174 		/* Convert back to ticks, with  */
4175 		KASSERT((tp->t_tmr_granularity == TCP_TMR_GRANULARITY_USEC),
4176 			("Granularity is not USEC its %u in tp:%p",
4177 			 tp->t_tmr_granularity, tp));
4178 		if (tp->t_srtt > 1) {
4179 			uint32_t val, frac;
4180 
4181 			val = USEC_2_TICKS(tp->t_srtt);
4182 			frac = tp->t_srtt % (HPTS_USEC_IN_SEC / hz);
4183 			tp->t_srtt = val << TCP_RTT_SHIFT;
4184 			/*
4185 			 * frac is the fractional part here is left
4186 			 * over from converting to hz and shifting.
4187 			 * We need to convert this to the 5 bit
4188 			 * remainder.
4189 			 */
4190 			if (frac) {
4191 				if (hz == 1000) {
4192 					frac = (((uint64_t)frac *  (uint64_t)TCP_RTT_SCALE) / (uint64_t)HPTS_USEC_IN_MSEC);
4193 				} else {
4194 					frac = (((uint64_t)frac * (uint64_t)(hz) * (uint64_t)TCP_RTT_SCALE) /(uint64_t)HPTS_USEC_IN_SEC);
4195 				}
4196 				tp->t_srtt += frac;
4197 			}
4198 		}
4199 		if (tp->t_rttvar) {
4200 			uint32_t val, frac;
4201 
4202 			val = USEC_2_TICKS(tp->t_rttvar);
4203 			frac = tp->t_srtt % (HPTS_USEC_IN_SEC / hz);
4204 			tp->t_rttvar = val <<  TCP_RTTVAR_SHIFT;
4205 			/*
4206 			 * frac is the fractional part here is left
4207 			 * over from converting to hz and shifting.
4208 			 * We need to convert this to the 5 bit
4209 			 * remainder.
4210 			 */
4211 			if (frac) {
4212 				if (hz == 1000) {
4213 					frac = (((uint64_t)frac *  (uint64_t)TCP_RTT_SCALE) / (uint64_t)HPTS_USEC_IN_MSEC);
4214 				} else {
4215 					frac = (((uint64_t)frac * (uint64_t)(hz) * (uint64_t)TCP_RTT_SCALE) /(uint64_t)HPTS_USEC_IN_SEC);
4216 				}
4217 				tp->t_rttvar += frac;
4218 			}
4219 		}
4220 		tp->t_rttlow = USEC_2_TICKS(tp->t_rttlow);
4221 		tp->t_tmr_granularity = TCP_TMR_GRANULARITY_TICKS;
4222 	}
4223 #ifdef INVARIANTS
4224 	else {
4225 		panic("Unknown granularity:%d tp:%p",
4226 		      granularity, tp);
4227 	}
4228 #endif
4229 }
4230 
4231 void
4232 tcp_handle_orphaned_packets(struct tcpcb *tp)
4233 {
4234 	struct mbuf *save, *m, *prev;
4235 	/*
4236 	 * Called when a stack switch is occuring from the fini()
4237 	 * of the old stack. We assue the init() as already been
4238 	 * run of the new stack and it has set the t_flags2 to
4239 	 * what it supports. This function will then deal with any
4240 	 * differences i.e. cleanup packets that maybe queued that
4241 	 * the newstack does not support.
4242 	 */
4243 
4244 	if (tp->t_flags2 & TF2_MBUF_L_ACKS)
4245 		return;
4246 	if ((tp->t_flags2 & TF2_SUPPORTS_MBUFQ) == 0 &&
4247 	    !STAILQ_EMPTY(&tp->t_inqueue)) {
4248 		/*
4249 		 * It is unsafe to process the packets since a
4250 		 * reset may be lurking in them (its rare but it
4251 		 * can occur). If we were to find a RST, then we
4252 		 * would end up dropping the connection and the
4253 		 * INP lock, so when we return the caller (tcp_usrreq)
4254 		 * will blow up when it trys to unlock the inp.
4255 		 * This new stack does not do any fancy LRO features
4256 		 * so all we can do is toss the packets.
4257 		 */
4258 		m = STAILQ_FIRST(&tp->t_inqueue);
4259 		STAILQ_INIT(&tp->t_inqueue);
4260 		STAILQ_FOREACH_FROM_SAFE(m, &tp->t_inqueue, m_stailqpkt, save)
4261 			m_freem(m);
4262 	} else {
4263 		/*
4264 		 * Here we have a stack that does mbuf queuing but
4265 		 * does not support compressed ack's. We must
4266 		 * walk all the mbufs and discard any compressed acks.
4267 		 */
4268 		STAILQ_FOREACH_SAFE(m, &tp->t_inqueue, m_stailqpkt, save) {
4269 			if (m->m_flags & M_ACKCMP) {
4270 				if (m == STAILQ_FIRST(&tp->t_inqueue))
4271 					STAILQ_REMOVE_HEAD(&tp->t_inqueue,
4272 					    m_stailqpkt);
4273 				else
4274 					STAILQ_REMOVE_AFTER(&tp->t_inqueue,
4275 					    prev, m_stailqpkt);
4276 				m_freem(m);
4277 			} else
4278 				prev = m;
4279 		}
4280 	}
4281 }
4282 
4283 #ifdef TCP_REQUEST_TRK
4284 uint32_t
4285 tcp_estimate_tls_overhead(struct socket *so, uint64_t tls_usr_bytes)
4286 {
4287 #ifdef KERN_TLS
4288 	struct ktls_session *tls;
4289 	uint32_t rec_oh, records;
4290 
4291 	tls = so->so_snd.sb_tls_info;
4292 	if (tls == NULL)
4293 	    return (0);
4294 
4295 	rec_oh = tls->params.tls_hlen + tls->params.tls_tlen;
4296 	records = ((tls_usr_bytes + tls->params.max_frame_len - 1)/tls->params.max_frame_len);
4297 	return (records * rec_oh);
4298 #else
4299 	return (0);
4300 #endif
4301 }
4302 
4303 extern uint32_t tcp_stale_entry_time;
4304 uint32_t tcp_stale_entry_time = 250000;
4305 SYSCTL_UINT(_net_inet_tcp, OID_AUTO, usrlog_stale, CTLFLAG_RW,
4306     &tcp_stale_entry_time, 250000, "Time that a tcpreq entry without a sendfile ages out");
4307 
4308 void
4309 tcp_req_log_req_info(struct tcpcb *tp, struct tcp_sendfile_track *req,
4310     uint16_t slot, uint8_t val, uint64_t offset, uint64_t nbytes)
4311 {
4312 	if (tcp_bblogging_on(tp)) {
4313 		union tcp_log_stackspecific log;
4314 		struct timeval tv;
4315 
4316 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
4317 #ifdef TCPHPTS
4318 		log.u_bbr.inhpts = tcp_in_hpts(tp);
4319 #endif
4320 		log.u_bbr.flex8 = val;
4321 		log.u_bbr.rttProp = req->timestamp;
4322 		log.u_bbr.delRate = req->start;
4323 		log.u_bbr.cur_del_rate = req->end;
4324 		log.u_bbr.flex1 = req->start_seq;
4325 		log.u_bbr.flex2 = req->end_seq;
4326 		log.u_bbr.flex3 = req->flags;
4327 		log.u_bbr.flex4 = ((req->localtime >> 32) & 0x00000000ffffffff);
4328 		log.u_bbr.flex5 = (req->localtime & 0x00000000ffffffff);
4329 		log.u_bbr.flex7 = slot;
4330 		log.u_bbr.bw_inuse = offset;
4331 		/* nbytes = flex6 | epoch */
4332 		log.u_bbr.flex6 = ((nbytes >> 32) & 0x00000000ffffffff);
4333 		log.u_bbr.epoch = (nbytes & 0x00000000ffffffff);
4334 		/* cspr =  lt_epoch | pkts_out */
4335 		log.u_bbr.lt_epoch = ((req->cspr >> 32) & 0x00000000ffffffff);
4336 		log.u_bbr.pkts_out |= (req->cspr & 0x00000000ffffffff);
4337 		log.u_bbr.applimited = tp->t_tcpreq_closed;
4338 		log.u_bbr.applimited <<= 8;
4339 		log.u_bbr.applimited |= tp->t_tcpreq_open;
4340 		log.u_bbr.applimited <<= 8;
4341 		log.u_bbr.applimited |= tp->t_tcpreq_req;
4342 		log.u_bbr.timeStamp = tcp_get_usecs(&tv);
4343 		TCP_LOG_EVENTP(tp, NULL,
4344 		    &tptosocket(tp)->so_rcv,
4345 		    &tptosocket(tp)->so_snd,
4346 		    TCP_LOG_REQ_T, 0,
4347 		    0, &log, false, &tv);
4348 	}
4349 }
4350 
4351 void
4352 tcp_req_free_a_slot(struct tcpcb *tp, struct tcp_sendfile_track *ent)
4353 {
4354 	if (tp->t_tcpreq_req > 0)
4355 		tp->t_tcpreq_req--;
4356 	if (ent->flags & TCP_TRK_TRACK_FLG_OPEN) {
4357 		if (tp->t_tcpreq_open > 0)
4358 			tp->t_tcpreq_open--;
4359 	} else {
4360 		if (tp->t_tcpreq_closed > 0)
4361 			tp->t_tcpreq_closed--;
4362 	}
4363 	ent->flags = TCP_TRK_TRACK_FLG_EMPTY;
4364 }
4365 
4366 static void
4367 tcp_req_check_for_stale_entries(struct tcpcb *tp, uint64_t ts, int rm_oldest)
4368 {
4369 	struct tcp_sendfile_track *ent;
4370 	uint64_t time_delta, oldest_delta;
4371 	int i, oldest, oldest_set = 0, cnt_rm = 0;
4372 
4373 	for(i = 0; i < MAX_TCP_TRK_REQ; i++) {
4374 		ent = &tp->t_tcpreq_info[i];
4375 		if (ent->flags != TCP_TRK_TRACK_FLG_USED) {
4376 			/*
4377 			 * We only care about closed end ranges
4378 			 * that are allocated and have no sendfile
4379 			 * ever touching them. They would be in
4380 			 * state USED.
4381 			 */
4382 			continue;
4383 		}
4384 		if (ts >= ent->localtime)
4385 			time_delta = ts - ent->localtime;
4386 		else
4387 			time_delta = 0;
4388 		if (time_delta &&
4389 		    ((oldest_delta < time_delta) || (oldest_set == 0))) {
4390 			oldest_set = 1;
4391 			oldest = i;
4392 			oldest_delta = time_delta;
4393 		}
4394 		if (tcp_stale_entry_time && (time_delta >= tcp_stale_entry_time)) {
4395 			/*
4396 			 * No sendfile in a our time-limit
4397 			 * time to purge it.
4398 			 */
4399 			cnt_rm++;
4400 			tcp_req_log_req_info(tp, &tp->t_tcpreq_info[i], i, TCP_TRK_REQ_LOG_STALE,
4401 					      time_delta, 0);
4402 			tcp_req_free_a_slot(tp, ent);
4403 		}
4404 	}
4405 	if ((cnt_rm == 0) && rm_oldest && oldest_set) {
4406 		ent = &tp->t_tcpreq_info[oldest];
4407 		tcp_req_log_req_info(tp, &tp->t_tcpreq_info[i], i, TCP_TRK_REQ_LOG_STALE,
4408 				      oldest_delta, 1);
4409 		tcp_req_free_a_slot(tp, ent);
4410 	}
4411 }
4412 
4413 int
4414 tcp_req_check_for_comp(struct tcpcb *tp, tcp_seq ack_point)
4415 {
4416 	int i, ret=0;
4417 	struct tcp_sendfile_track *ent;
4418 
4419 	/* Clean up any old closed end requests that are now completed */
4420 	if (tp->t_tcpreq_req == 0)
4421 		return(0);
4422 	if (tp->t_tcpreq_closed == 0)
4423 		return(0);
4424 	for(i = 0; i < MAX_TCP_TRK_REQ; i++) {
4425 		ent = &tp->t_tcpreq_info[i];
4426 		/* Skip empty ones */
4427 		if (ent->flags == TCP_TRK_TRACK_FLG_EMPTY)
4428 			continue;
4429 		/* Skip open ones */
4430 		if (ent->flags & TCP_TRK_TRACK_FLG_OPEN)
4431 			continue;
4432 		if (SEQ_GEQ(ack_point, ent->end_seq)) {
4433 			/* We are past it -- free it */
4434 			tcp_req_log_req_info(tp, ent,
4435 					      i, TCP_TRK_REQ_LOG_FREED, 0, 0);
4436 			tcp_req_free_a_slot(tp, ent);
4437 			ret++;
4438 		}
4439 	}
4440 	return (ret);
4441 }
4442 
4443 int
4444 tcp_req_is_entry_comp(struct tcpcb *tp, struct tcp_sendfile_track *ent, tcp_seq ack_point)
4445 {
4446 	if (tp->t_tcpreq_req == 0)
4447 		return(-1);
4448 	if (tp->t_tcpreq_closed == 0)
4449 		return(-1);
4450 	if (ent->flags == TCP_TRK_TRACK_FLG_EMPTY)
4451 		return(-1);
4452 	if (SEQ_GEQ(ack_point, ent->end_seq)) {
4453 		return (1);
4454 	}
4455 	return (0);
4456 }
4457 
4458 struct tcp_sendfile_track *
4459 tcp_req_find_a_req_that_is_completed_by(struct tcpcb *tp, tcp_seq th_ack, int *ip)
4460 {
4461 	/*
4462 	 * Given an ack point (th_ack) walk through our entries and
4463 	 * return the first one found that th_ack goes past the
4464 	 * end_seq.
4465 	 */
4466 	struct tcp_sendfile_track *ent;
4467 	int i;
4468 
4469 	if (tp->t_tcpreq_req == 0) {
4470 		/* none open */
4471 		return (NULL);
4472 	}
4473 	for(i = 0; i < MAX_TCP_TRK_REQ; i++) {
4474 		ent = &tp->t_tcpreq_info[i];
4475 		if (ent->flags == TCP_TRK_TRACK_FLG_EMPTY)
4476 			continue;
4477 		if ((ent->flags & TCP_TRK_TRACK_FLG_OPEN) == 0) {
4478 			if (SEQ_GEQ(th_ack, ent->end_seq)) {
4479 				*ip = i;
4480 				return (ent);
4481 			}
4482 		}
4483 	}
4484 	return (NULL);
4485 }
4486 
4487 struct tcp_sendfile_track *
4488 tcp_req_find_req_for_seq(struct tcpcb *tp, tcp_seq seq)
4489 {
4490 	struct tcp_sendfile_track *ent;
4491 	int i;
4492 
4493 	if (tp->t_tcpreq_req == 0) {
4494 		/* none open */
4495 		return (NULL);
4496 	}
4497 	for(i = 0; i < MAX_TCP_TRK_REQ; i++) {
4498 		ent = &tp->t_tcpreq_info[i];
4499 		tcp_req_log_req_info(tp, ent, i, TCP_TRK_REQ_LOG_SEARCH,
4500 				      (uint64_t)seq, 0);
4501 		if (ent->flags == TCP_TRK_TRACK_FLG_EMPTY) {
4502 			continue;
4503 		}
4504 		if (ent->flags & TCP_TRK_TRACK_FLG_OPEN) {
4505 			/*
4506 			 * An open end request only needs to
4507 			 * match the beginning seq or be
4508 			 * all we have (once we keep going on
4509 			 * a open end request we may have a seq
4510 			 * wrap).
4511 			 */
4512 			if ((SEQ_GEQ(seq, ent->start_seq)) ||
4513 			    (tp->t_tcpreq_closed == 0))
4514 				return (ent);
4515 		} else {
4516 			/*
4517 			 * For this one we need to
4518 			 * be a bit more careful if its
4519 			 * completed at least.
4520 			 */
4521 			if ((SEQ_GEQ(seq, ent->start_seq)) &&
4522 			    (SEQ_LT(seq, ent->end_seq))) {
4523 				return (ent);
4524 			}
4525 		}
4526 	}
4527 	return (NULL);
4528 }
4529 
4530 /* Should this be in its own file tcp_req.c ? */
4531 struct tcp_sendfile_track *
4532 tcp_req_alloc_req_full(struct tcpcb *tp, struct tcp_snd_req *req, uint64_t ts, int rec_dups)
4533 {
4534 	struct tcp_sendfile_track *fil;
4535 	int i, allocated;
4536 
4537 	/* In case the stack does not check for completions do so now */
4538 	tcp_req_check_for_comp(tp, tp->snd_una);
4539 	/* Check for stale entries */
4540 	if (tp->t_tcpreq_req)
4541 		tcp_req_check_for_stale_entries(tp, ts,
4542 		    (tp->t_tcpreq_req >= MAX_TCP_TRK_REQ));
4543 	/* Check to see if this is a duplicate of one not started */
4544 	if (tp->t_tcpreq_req) {
4545 		for(i = 0, allocated = 0; i < MAX_TCP_TRK_REQ; i++) {
4546 			fil = &tp->t_tcpreq_info[i];
4547 			if (fil->flags != TCP_TRK_TRACK_FLG_USED)
4548 				continue;
4549 			if ((fil->timestamp == req->timestamp) &&
4550 			    (fil->start == req->start) &&
4551 			    ((fil->flags & TCP_TRK_TRACK_FLG_OPEN) ||
4552 			     (fil->end == req->end))) {
4553 				/*
4554 				 * We already have this request
4555 				 * and it has not been started with sendfile.
4556 				 * This probably means the user was returned
4557 				 * a 4xx of some sort and its going to age
4558 				 * out, lets not duplicate it.
4559 				 */
4560 				return(fil);
4561 			}
4562 		}
4563 	}
4564 	/* Ok if there is no room at the inn we are in trouble */
4565 	if (tp->t_tcpreq_req >= MAX_TCP_TRK_REQ) {
4566 		tcp_trace_point(tp, TCP_TP_REQ_LOG_FAIL);
4567 		for(i = 0; i < MAX_TCP_TRK_REQ; i++) {
4568 			tcp_req_log_req_info(tp, &tp->t_tcpreq_info[i],
4569 			    i, TCP_TRK_REQ_LOG_ALLOCFAIL, 0, 0);
4570 		}
4571 		return (NULL);
4572 	}
4573 	for(i = 0, allocated = 0; i < MAX_TCP_TRK_REQ; i++) {
4574 		fil = &tp->t_tcpreq_info[i];
4575 		if (fil->flags == TCP_TRK_TRACK_FLG_EMPTY) {
4576 			allocated = 1;
4577 			fil->flags = TCP_TRK_TRACK_FLG_USED;
4578 			fil->timestamp = req->timestamp;
4579 			fil->localtime = ts;
4580 			fil->start = req->start;
4581 			if (req->flags & TCP_LOG_HTTPD_RANGE_END) {
4582 				fil->end = req->end;
4583 			} else {
4584 				fil->end = 0;
4585 				fil->flags |= TCP_TRK_TRACK_FLG_OPEN;
4586 			}
4587 			/*
4588 			 * We can set the min boundaries to the TCP Sequence space,
4589 			 * but it might be found to be further up when sendfile
4590 			 * actually runs on this range (if it ever does).
4591 			 */
4592 			fil->sbcc_at_s = tptosocket(tp)->so_snd.sb_ccc;
4593 			fil->start_seq = tp->snd_una +
4594 			    tptosocket(tp)->so_snd.sb_ccc;
4595 			fil->end_seq = (fil->start_seq + ((uint32_t)(fil->end - fil->start)));
4596 			if (tptosocket(tp)->so_snd.sb_tls_info) {
4597 				/*
4598 				 * This session is doing TLS. Take a swag guess
4599 				 * at the overhead.
4600 				 */
4601 				fil->end_seq += tcp_estimate_tls_overhead(
4602 				    tptosocket(tp), (fil->end - fil->start));
4603 			}
4604 			tp->t_tcpreq_req++;
4605 			if (fil->flags & TCP_TRK_TRACK_FLG_OPEN)
4606 				tp->t_tcpreq_open++;
4607 			else
4608 				tp->t_tcpreq_closed++;
4609 			tcp_req_log_req_info(tp, fil, i,
4610 			    TCP_TRK_REQ_LOG_NEW, 0, 0);
4611 			break;
4612 		} else
4613 			fil = NULL;
4614 	}
4615 	return (fil);
4616 }
4617 
4618 void
4619 tcp_req_alloc_req(struct tcpcb *tp, union tcp_log_userdata *user, uint64_t ts)
4620 {
4621 	(void)tcp_req_alloc_req_full(tp, &user->tcp_req, ts, 1);
4622 }
4623 #endif
4624 
4625 void
4626 tcp_log_socket_option(struct tcpcb *tp, uint32_t option_num, uint32_t option_val, int err)
4627 {
4628 	if (tcp_bblogging_on(tp)) {
4629 		struct tcp_log_buffer *l;
4630 
4631 		l = tcp_log_event(tp, NULL,
4632 		        &tptosocket(tp)->so_rcv,
4633 		        &tptosocket(tp)->so_snd,
4634 		        TCP_LOG_SOCKET_OPT,
4635 		        err, 0, NULL, 1,
4636 		        NULL, NULL, 0, NULL);
4637 		if (l) {
4638 			l->tlb_flex1 = option_num;
4639 			l->tlb_flex2 = option_val;
4640 		}
4641 	}
4642 }
4643 
4644 uint32_t
4645 tcp_get_srtt(struct tcpcb *tp, int granularity)
4646 {
4647 	uint32_t srtt;
4648 
4649 	KASSERT(granularity == TCP_TMR_GRANULARITY_USEC ||
4650 	    granularity == TCP_TMR_GRANULARITY_TICKS,
4651 	    ("%s: called with unexpected granularity %d", __func__,
4652 	    granularity));
4653 
4654 	srtt = tp->t_srtt;
4655 
4656 	/*
4657 	 * We only support two granularities. If the stored granularity
4658 	 * does not match the granularity requested by the caller,
4659 	 * convert the stored value to the requested unit of granularity.
4660 	 */
4661 	if (tp->t_tmr_granularity != granularity) {
4662 		if (granularity == TCP_TMR_GRANULARITY_USEC)
4663 			srtt = TICKS_2_USEC(srtt);
4664 		else
4665 			srtt = USEC_2_TICKS(srtt);
4666 	}
4667 
4668 	/*
4669 	 * If the srtt is stored with ticks granularity, we need to
4670 	 * unshift to get the actual value. We do this after the
4671 	 * conversion above (if one was necessary) in order to maximize
4672 	 * precision.
4673 	 */
4674 	if (tp->t_tmr_granularity == TCP_TMR_GRANULARITY_TICKS)
4675 		srtt = srtt >> TCP_RTT_SHIFT;
4676 
4677 	return (srtt);
4678 }
4679 
4680 void
4681 tcp_account_for_send(struct tcpcb *tp, uint32_t len, uint8_t is_rxt,
4682     uint8_t is_tlp, bool hw_tls)
4683 {
4684 
4685 	if (is_tlp) {
4686 		tp->t_sndtlppack++;
4687 		tp->t_sndtlpbyte += len;
4688 	}
4689 	/* To get total bytes sent you must add t_snd_rxt_bytes to t_sndbytes */
4690 	if (is_rxt)
4691 		tp->t_snd_rxt_bytes += len;
4692 	else
4693 		tp->t_sndbytes += len;
4694 
4695 #ifdef KERN_TLS
4696 	if (hw_tls && is_rxt && len != 0) {
4697 		uint64_t rexmit_percent;
4698 
4699 		rexmit_percent = (1000ULL * tp->t_snd_rxt_bytes) /
4700 		    (10ULL * (tp->t_snd_rxt_bytes + tp->t_sndbytes));
4701 		if (rexmit_percent > ktls_ifnet_max_rexmit_pct)
4702 			ktls_disable_ifnet(tp);
4703 	}
4704 #endif
4705 }
4706