1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_inet.h" 36 #include "opt_inet6.h" 37 #include "opt_tcpdebug.h" 38 39 #include <sys/param.h> 40 #include <sys/kernel.h> 41 #include <sys/malloc.h> 42 #include <sys/mbuf.h> 43 #include <sys/socket.h> 44 #include <sys/socketvar.h> 45 #include <sys/sysctl.h> 46 #include <sys/syslog.h> 47 #include <sys/systm.h> 48 49 #include <vm/uma.h> 50 51 #include <net/if.h> 52 #include <net/route.h> 53 54 #include <netinet/in.h> 55 #include <netinet/in_pcb.h> 56 #include <netinet/in_systm.h> 57 #include <netinet/in_var.h> 58 #include <netinet/ip.h> 59 #include <netinet/ip_var.h> 60 #include <netinet/ip_options.h> 61 #include <netinet/ip6.h> 62 #include <netinet6/in6_pcb.h> 63 #include <netinet6/ip6_var.h> 64 #include <netinet6/nd6.h> 65 #include <netinet/tcp.h> 66 #include <netinet/tcp_fsm.h> 67 #include <netinet/tcp_seq.h> 68 #include <netinet/tcp_timer.h> 69 #include <netinet/tcp_var.h> 70 #include <netinet6/tcp6_var.h> 71 #include <netinet/tcpip.h> 72 #ifdef TCPDEBUG 73 #include <netinet/tcp_debug.h> 74 #endif /* TCPDEBUG */ 75 76 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 77 "TCP Segment Reassembly Queue"); 78 79 static int tcp_reass_maxseg = 0; 80 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 81 &tcp_reass_maxseg, 0, 82 "Global maximum number of TCP Segments in Reassembly Queue"); 83 84 int tcp_reass_qsize = 0; 85 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD, 86 &tcp_reass_qsize, 0, 87 "Global number of TCP Segments currently in Reassembly Queue"); 88 89 static int tcp_reass_maxqlen = 48; 90 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxqlen, CTLFLAG_RW, 91 &tcp_reass_maxqlen, 0, 92 "Maximum number of TCP Segments per individual Reassembly Queue"); 93 94 static int tcp_reass_overflows = 0; 95 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD, 96 &tcp_reass_overflows, 0, 97 "Global number of TCP Segment Reassembly Queue Overflows"); 98 99 /* Initialize TCP reassembly queue */ 100 static void 101 tcp_reass_zone_change(void *tag) 102 { 103 104 tcp_reass_maxseg = nmbclusters / 16; 105 uma_zone_set_max(tcp_reass_zone, tcp_reass_maxseg); 106 } 107 108 uma_zone_t tcp_reass_zone; 109 110 void 111 tcp_reass_init(void) 112 { 113 114 tcp_reass_maxseg = nmbclusters / 16; 115 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 116 &tcp_reass_maxseg); 117 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 118 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 119 uma_zone_set_max(tcp_reass_zone, tcp_reass_maxseg); 120 EVENTHANDLER_REGISTER(nmbclusters_change, 121 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 122 } 123 124 int 125 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) 126 { 127 struct tseg_qent *q; 128 struct tseg_qent *p = NULL; 129 struct tseg_qent *nq; 130 struct tseg_qent *te = NULL; 131 struct socket *so = tp->t_inpcb->inp_socket; 132 int flags; 133 134 INP_LOCK_ASSERT(tp->t_inpcb); 135 136 /* 137 * XXX: tcp_reass() is rather inefficient with its data structures 138 * and should be rewritten (see NetBSD for optimizations). While 139 * doing that it should move to its own file tcp_reass.c. 140 */ 141 142 /* 143 * Call with th==NULL after become established to 144 * force pre-ESTABLISHED data up to user socket. 145 */ 146 if (th == NULL) 147 goto present; 148 149 /* 150 * Limit the number of segments in the reassembly queue to prevent 151 * holding on to too many segments (and thus running out of mbufs). 152 * Make sure to let the missing segment through which caused this 153 * queue. Always keep one global queue entry spare to be able to 154 * process the missing segment. 155 */ 156 if (th->th_seq != tp->rcv_nxt && 157 (tcp_reass_qsize + 1 >= tcp_reass_maxseg || 158 tp->t_segqlen >= tcp_reass_maxqlen)) { 159 tcp_reass_overflows++; 160 tcpstat.tcps_rcvmemdrop++; 161 m_freem(m); 162 *tlenp = 0; 163 return (0); 164 } 165 166 /* 167 * Allocate a new queue entry. If we can't, or hit the zone limit 168 * just drop the pkt. 169 */ 170 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 171 if (te == NULL) { 172 tcpstat.tcps_rcvmemdrop++; 173 m_freem(m); 174 *tlenp = 0; 175 return (0); 176 } 177 tp->t_segqlen++; 178 tcp_reass_qsize++; 179 180 /* 181 * Find a segment which begins after this one does. 182 */ 183 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 184 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 185 break; 186 p = q; 187 } 188 189 /* 190 * If there is a preceding segment, it may provide some of 191 * our data already. If so, drop the data from the incoming 192 * segment. If it provides all of our data, drop us. 193 */ 194 if (p != NULL) { 195 int i; 196 /* conversion to int (in i) handles seq wraparound */ 197 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 198 if (i > 0) { 199 if (i >= *tlenp) { 200 tcpstat.tcps_rcvduppack++; 201 tcpstat.tcps_rcvdupbyte += *tlenp; 202 m_freem(m); 203 uma_zfree(tcp_reass_zone, te); 204 tp->t_segqlen--; 205 tcp_reass_qsize--; 206 /* 207 * Try to present any queued data 208 * at the left window edge to the user. 209 * This is needed after the 3-WHS 210 * completes. 211 */ 212 goto present; /* ??? */ 213 } 214 m_adj(m, i); 215 *tlenp -= i; 216 th->th_seq += i; 217 } 218 } 219 tcpstat.tcps_rcvoopack++; 220 tcpstat.tcps_rcvoobyte += *tlenp; 221 222 /* 223 * While we overlap succeeding segments trim them or, 224 * if they are completely covered, dequeue them. 225 */ 226 while (q) { 227 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 228 if (i <= 0) 229 break; 230 if (i < q->tqe_len) { 231 q->tqe_th->th_seq += i; 232 q->tqe_len -= i; 233 m_adj(q->tqe_m, i); 234 break; 235 } 236 237 nq = LIST_NEXT(q, tqe_q); 238 LIST_REMOVE(q, tqe_q); 239 m_freem(q->tqe_m); 240 uma_zfree(tcp_reass_zone, q); 241 tp->t_segqlen--; 242 tcp_reass_qsize--; 243 q = nq; 244 } 245 246 /* Insert the new segment queue entry into place. */ 247 te->tqe_m = m; 248 te->tqe_th = th; 249 te->tqe_len = *tlenp; 250 251 if (p == NULL) { 252 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 253 } else { 254 LIST_INSERT_AFTER(p, te, tqe_q); 255 } 256 257 present: 258 /* 259 * Present data to user, advancing rcv_nxt through 260 * completed sequence space. 261 */ 262 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 263 return (0); 264 q = LIST_FIRST(&tp->t_segq); 265 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 266 return (0); 267 SOCKBUF_LOCK(&so->so_rcv); 268 do { 269 tp->rcv_nxt += q->tqe_len; 270 flags = q->tqe_th->th_flags & TH_FIN; 271 nq = LIST_NEXT(q, tqe_q); 272 LIST_REMOVE(q, tqe_q); 273 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 274 m_freem(q->tqe_m); 275 else 276 sbappendstream_locked(&so->so_rcv, q->tqe_m); 277 uma_zfree(tcp_reass_zone, q); 278 tp->t_segqlen--; 279 tcp_reass_qsize--; 280 q = nq; 281 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 282 ND6_HINT(tp); 283 sorwakeup_locked(so); 284 return (flags); 285 } 286