xref: /linux/tools/testing/selftests/drivers/net/gro.c (revision 6f74bc8b6e8d0e8218c1342682dadb156603d13e)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * This testsuite provides conformance testing for GRO coalescing.
4  *
5  * Test cases:
6  *
7  * data_*:
8  *  Data packets of the same size and same header setup with correct
9  *  sequence numbers coalesce. The one exception being the last data
10  *  packet coalesced: it can be smaller than the rest and coalesced
11  *  as long as it is in the same flow.
12  *   - data_same:    same size packets coalesce
13  *   - data_lrg_sml: large then small coalesces
14  *   - data_sml_lrg: small then large doesn't coalesce
15  *
16  * ack:
17  *  Pure ACK does not coalesce.
18  *
19  * flags_*:
20  *  No packets with PSH, SYN, URG, RST, CWR set will be coalesced.
21  *   - flags_psh, flags_syn, flags_rst, flags_urg, flags_cwr
22  *
23  * tcp_*:
24  *  Packets with incorrect checksum, non-consecutive seqno and
25  *  different TCP header options shouldn't coalesce. Nit: given that
26  *  some extension headers have paddings, such as timestamp, headers
27  *  that are padded differently would not be coalesced.
28  *   - tcp_csum: incorrect checksum
29  *   - tcp_seq:  non-consecutive sequence numbers
30  *   - tcp_ts:   different timestamps
31  *   - tcp_opt:  different TCP options
32  *
33  * ip_*:
34  *  Packets with different (ECN, TTL, TOS) header, IP options or
35  *  IP fragments shouldn't coalesce.
36  *   - ip_ecn, ip_tos:            shared between IPv4/IPv6
37  *   - ip_ttl, ip_opt, ip_frag4:  IPv4 only
38  *   - ip_id_df*:                 IPv4 IP ID field coalescing tests
39  *   - ip_frag6, ip_v6ext_*:      IPv6 only
40  *
41  * large_*:
42  *  Packets larger than GRO_MAX_SIZE packets shouldn't coalesce.
43  *   - large_max: exceeding max size
44  *   - large_rem: remainder handling
45  *
46  * MSS is defined as 4096 - header because if it is too small
47  * (i.e. 1500 MTU - header), it will result in many packets,
48  * increasing the "large" test case's flakiness. This is because
49  * due to time sensitivity in the coalescing window, the receiver
50  * may not coalesce all of the packets.
51  *
52  * Note the timing issue applies to all of the test cases, so some
53  * flakiness is to be expected.
54  *
55  */
56 
57 #define _GNU_SOURCE
58 
59 #include <arpa/inet.h>
60 #include <errno.h>
61 #include <error.h>
62 #include <getopt.h>
63 #include <linux/filter.h>
64 #include <linux/if_packet.h>
65 #include <linux/ipv6.h>
66 #include <net/ethernet.h>
67 #include <net/if.h>
68 #include <netinet/in.h>
69 #include <netinet/ip.h>
70 #include <netinet/ip6.h>
71 #include <netinet/tcp.h>
72 #include <stdbool.h>
73 #include <stddef.h>
74 #include <stdio.h>
75 #include <stdarg.h>
76 #include <string.h>
77 #include <unistd.h>
78 
79 #include "kselftest.h"
80 #include "../../net/lib/ksft.h"
81 
82 #define DPORT 8000
83 #define SPORT 1500
84 #define PAYLOAD_LEN 100
85 #define NUM_PACKETS 4
86 #define START_SEQ 100
87 #define START_ACK 100
88 #define ETH_P_NONE 0
89 #define TOTAL_HDR_LEN (ETH_HLEN + sizeof(struct ipv6hdr) + sizeof(struct tcphdr))
90 #define MSS (4096 - sizeof(struct tcphdr) - sizeof(struct ipv6hdr))
91 #define MAX_PAYLOAD (IP_MAXPACKET - sizeof(struct tcphdr) - sizeof(struct ipv6hdr))
92 #define NUM_LARGE_PKT (MAX_PAYLOAD / MSS)
93 #define MAX_HDR_LEN (ETH_HLEN + sizeof(struct ipv6hdr) + sizeof(struct tcphdr))
94 #define MIN_EXTHDR_SIZE 8
95 #define EXT_PAYLOAD_1 "\x00\x00\x00\x00\x00\x00"
96 #define EXT_PAYLOAD_2 "\x11\x11\x11\x11\x11\x11"
97 
98 #define ipv6_optlen(p)  (((p)->hdrlen+1) << 3) /* calculate IPv6 extension header len */
99 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
100 
101 enum flush_id_case {
102 	FLUSH_ID_DF1_INC,
103 	FLUSH_ID_DF1_FIXED,
104 	FLUSH_ID_DF0_INC,
105 	FLUSH_ID_DF0_FIXED,
106 	FLUSH_ID_DF1_INC_FIXED,
107 	FLUSH_ID_DF1_FIXED_INC,
108 };
109 
110 static const char *addr6_src = "fdaa::2";
111 static const char *addr6_dst = "fdaa::1";
112 static const char *addr4_src = "192.168.1.200";
113 static const char *addr4_dst = "192.168.1.100";
114 static int proto = -1;
115 static uint8_t src_mac[ETH_ALEN], dst_mac[ETH_ALEN];
116 static char *testname = "data";
117 static char *ifname = "eth0";
118 static char *smac = "aa:00:00:00:00:02";
119 static char *dmac = "aa:00:00:00:00:01";
120 static bool verbose;
121 static bool tx_socket = true;
122 static int tcp_offset = -1;
123 static int total_hdr_len = -1;
124 static int ethhdr_proto = -1;
125 static bool ipip;
126 
127 static void vlog(const char *fmt, ...)
128 {
129 	va_list args;
130 
131 	if (verbose) {
132 		va_start(args, fmt);
133 		vfprintf(stderr, fmt, args);
134 		va_end(args);
135 	}
136 }
137 
138 static void setup_sock_filter(int fd)
139 {
140 	const int dport_off = tcp_offset + offsetof(struct tcphdr, dest);
141 	const int ethproto_off = offsetof(struct ethhdr, h_proto);
142 	int optlen = 0;
143 	int ipproto_off, opt_ipproto_off;
144 	int next_off;
145 
146 	if (ipip)
147 		next_off = sizeof(struct iphdr) + offsetof(struct iphdr, protocol);
148 	else if (proto == PF_INET)
149 		next_off = offsetof(struct iphdr, protocol);
150 	else
151 		next_off = offsetof(struct ipv6hdr, nexthdr);
152 	ipproto_off = ETH_HLEN + next_off;
153 
154 	/* Overridden later if exthdrs are used: */
155 	opt_ipproto_off = ipproto_off;
156 
157 	if (strcmp(testname, "ip_opt") == 0) {
158 		optlen = sizeof(struct ip_timestamp);
159 	} else if (strcmp(testname, "ip_frag6") == 0 ||
160 		   strcmp(testname, "ip_v6ext_same") == 0 ||
161 		   strcmp(testname, "ip_v6ext_diff") == 0) {
162 		BUILD_BUG_ON(sizeof(struct ip6_hbh) > MIN_EXTHDR_SIZE);
163 		BUILD_BUG_ON(sizeof(struct ip6_dest) > MIN_EXTHDR_SIZE);
164 		BUILD_BUG_ON(sizeof(struct ip6_frag) > MIN_EXTHDR_SIZE);
165 
166 		/* same size for HBH and Fragment extension header types */
167 		optlen = MIN_EXTHDR_SIZE;
168 		opt_ipproto_off = ETH_HLEN + sizeof(struct ipv6hdr)
169 			+ offsetof(struct ip6_ext, ip6e_nxt);
170 	}
171 
172 	/* this filter validates the following:
173 	 *	- packet is IPv4/IPv6 according to the running test.
174 	 *	- packet is TCP. Also handles the case of one extension header and then TCP.
175 	 *	- checks the packet tcp dport equals to DPORT. Also handles the case of one
176 	 *	  extension header and then TCP.
177 	 */
178 	struct sock_filter filter[] = {
179 			BPF_STMT(BPF_LD  + BPF_H   + BPF_ABS, ethproto_off),
180 			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ntohs(ethhdr_proto), 0, 9),
181 			BPF_STMT(BPF_LD  + BPF_B   + BPF_ABS, ipproto_off),
182 			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_TCP, 2, 0),
183 			BPF_STMT(BPF_LD  + BPF_B   + BPF_ABS, opt_ipproto_off),
184 			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_TCP, 0, 5),
185 			BPF_STMT(BPF_LD  + BPF_H   + BPF_ABS, dport_off),
186 			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DPORT, 2, 0),
187 			BPF_STMT(BPF_LD  + BPF_H   + BPF_ABS, dport_off + optlen),
188 			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DPORT, 0, 1),
189 			BPF_STMT(BPF_RET + BPF_K, 0xFFFFFFFF),
190 			BPF_STMT(BPF_RET + BPF_K, 0),
191 	};
192 
193 	struct sock_fprog bpf = {
194 		.len = ARRAY_SIZE(filter),
195 		.filter = filter,
196 	};
197 
198 	if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &bpf, sizeof(bpf)) < 0)
199 		error(1, errno, "error setting filter");
200 }
201 
202 static uint32_t checksum_nofold(void *data, size_t len, uint32_t sum)
203 {
204 	uint16_t *words = data;
205 	int i;
206 
207 	for (i = 0; i < len / 2; i++)
208 		sum += words[i];
209 	if (len & 1)
210 		sum += ((char *)data)[len - 1];
211 	return sum;
212 }
213 
214 static uint16_t checksum_fold(void *data, size_t len, uint32_t sum)
215 {
216 	sum = checksum_nofold(data, len, sum);
217 	while (sum > 0xFFFF)
218 		sum = (sum & 0xFFFF) + (sum >> 16);
219 	return ~sum;
220 }
221 
222 static uint16_t tcp_checksum(void *buf, int payload_len)
223 {
224 	struct pseudo_header6 {
225 		struct in6_addr saddr;
226 		struct in6_addr daddr;
227 		uint16_t protocol;
228 		uint16_t payload_len;
229 	} ph6;
230 	struct pseudo_header4 {
231 		struct in_addr saddr;
232 		struct in_addr daddr;
233 		uint16_t protocol;
234 		uint16_t payload_len;
235 	} ph4;
236 	uint32_t sum = 0;
237 
238 	if (proto == PF_INET6) {
239 		if (inet_pton(AF_INET6, addr6_src, &ph6.saddr) != 1)
240 			error(1, errno, "inet_pton6 source ip pseudo");
241 		if (inet_pton(AF_INET6, addr6_dst, &ph6.daddr) != 1)
242 			error(1, errno, "inet_pton6 dest ip pseudo");
243 		ph6.protocol = htons(IPPROTO_TCP);
244 		ph6.payload_len = htons(sizeof(struct tcphdr) + payload_len);
245 
246 		sum = checksum_nofold(&ph6, sizeof(ph6), 0);
247 	} else if (proto == PF_INET) {
248 		if (inet_pton(AF_INET, addr4_src, &ph4.saddr) != 1)
249 			error(1, errno, "inet_pton source ip pseudo");
250 		if (inet_pton(AF_INET, addr4_dst, &ph4.daddr) != 1)
251 			error(1, errno, "inet_pton dest ip pseudo");
252 		ph4.protocol = htons(IPPROTO_TCP);
253 		ph4.payload_len = htons(sizeof(struct tcphdr) + payload_len);
254 
255 		sum = checksum_nofold(&ph4, sizeof(ph4), 0);
256 	}
257 
258 	return checksum_fold(buf, sizeof(struct tcphdr) + payload_len, sum);
259 }
260 
261 static void read_MAC(uint8_t *mac_addr, char *mac)
262 {
263 	if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
264 		   &mac_addr[0], &mac_addr[1], &mac_addr[2],
265 		   &mac_addr[3], &mac_addr[4], &mac_addr[5]) != 6)
266 		error(1, 0, "sscanf");
267 }
268 
269 static void fill_datalinklayer(void *buf)
270 {
271 	struct ethhdr *eth = buf;
272 
273 	memcpy(eth->h_dest, dst_mac, ETH_ALEN);
274 	memcpy(eth->h_source, src_mac, ETH_ALEN);
275 	eth->h_proto = ethhdr_proto;
276 }
277 
278 static void fill_networklayer(void *buf, int payload_len, int protocol)
279 {
280 	struct ipv6hdr *ip6h = buf;
281 	struct iphdr *iph = buf;
282 
283 	if (proto == PF_INET6) {
284 		memset(ip6h, 0, sizeof(*ip6h));
285 
286 		ip6h->version = 6;
287 		ip6h->payload_len = htons(sizeof(struct tcphdr) + payload_len);
288 		ip6h->nexthdr = protocol;
289 		ip6h->hop_limit = 8;
290 		if (inet_pton(AF_INET6, addr6_src, &ip6h->saddr) != 1)
291 			error(1, errno, "inet_pton source ip6");
292 		if (inet_pton(AF_INET6, addr6_dst, &ip6h->daddr) != 1)
293 			error(1, errno, "inet_pton dest ip6");
294 	} else if (proto == PF_INET) {
295 		memset(iph, 0, sizeof(*iph));
296 
297 		iph->version = 4;
298 		iph->ihl = 5;
299 		iph->ttl = 8;
300 		iph->protocol	= protocol;
301 		iph->tot_len = htons(sizeof(struct tcphdr) +
302 				payload_len + sizeof(struct iphdr));
303 		iph->frag_off = htons(0x4000); /* DF = 1, MF = 0 */
304 		if (inet_pton(AF_INET, addr4_src, &iph->saddr) != 1)
305 			error(1, errno, "inet_pton source ip");
306 		if (inet_pton(AF_INET, addr4_dst, &iph->daddr) != 1)
307 			error(1, errno, "inet_pton dest ip");
308 		iph->check = checksum_fold(buf, sizeof(struct iphdr), 0);
309 	}
310 }
311 
312 static void fill_transportlayer(void *buf, int seq_offset, int ack_offset,
313 				int payload_len, int fin)
314 {
315 	struct tcphdr *tcph = buf;
316 
317 	memset(tcph, 0, sizeof(*tcph));
318 
319 	tcph->source = htons(SPORT);
320 	tcph->dest = htons(DPORT);
321 	tcph->seq = ntohl(START_SEQ + seq_offset);
322 	tcph->ack_seq = ntohl(START_ACK + ack_offset);
323 	tcph->ack = 1;
324 	tcph->fin = fin;
325 	tcph->doff = 5;
326 	tcph->window = htons(TCP_MAXWIN);
327 	tcph->urg_ptr = 0;
328 	tcph->check = tcp_checksum(tcph, payload_len);
329 }
330 
331 static void write_packet(int fd, char *buf, int len, struct sockaddr_ll *daddr)
332 {
333 	int ret = -1;
334 
335 	ret = sendto(fd, buf, len, 0, (struct sockaddr *)daddr, sizeof(*daddr));
336 	if (ret == -1)
337 		error(1, errno, "sendto failure");
338 	if (ret != len)
339 		error(1, errno, "sendto wrong length");
340 }
341 
342 static void create_packet(void *buf, int seq_offset, int ack_offset,
343 			  int payload_len, int fin)
344 {
345 	memset(buf, 0, total_hdr_len);
346 	memset(buf + total_hdr_len, 'a', payload_len);
347 
348 	fill_transportlayer(buf + tcp_offset, seq_offset, ack_offset,
349 			    payload_len, fin);
350 
351 	if (ipip) {
352 		fill_networklayer(buf + ETH_HLEN, payload_len + sizeof(struct iphdr),
353 				  IPPROTO_IPIP);
354 		fill_networklayer(buf + ETH_HLEN + sizeof(struct iphdr),
355 				  payload_len, IPPROTO_TCP);
356 	} else {
357 		fill_networklayer(buf + ETH_HLEN, payload_len, IPPROTO_TCP);
358 	}
359 
360 	fill_datalinklayer(buf);
361 }
362 
363 #ifndef TH_CWR
364 #define TH_CWR 0x80
365 #endif
366 static void set_flags(struct tcphdr *tcph, int payload_len, int psh, int syn,
367 		      int rst, int urg, int cwr)
368 {
369 	tcph->psh = psh;
370 	tcph->syn = syn;
371 	tcph->rst = rst;
372 	tcph->urg = urg;
373 	if (cwr)
374 		tcph->th_flags |= TH_CWR;
375 	else
376 		tcph->th_flags &= ~TH_CWR;
377 	tcph->check = 0;
378 	tcph->check = tcp_checksum(tcph, payload_len);
379 }
380 
381 /* send extra flags of the (NUM_PACKETS / 2) and (NUM_PACKETS / 2 - 1)
382  * pkts, not first and not last pkt
383  */
384 static void send_flags(int fd, struct sockaddr_ll *daddr, int psh, int syn,
385 		       int rst, int urg, int cwr)
386 {
387 	static char flag_buf[2][MAX_HDR_LEN + PAYLOAD_LEN];
388 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
389 	int payload_len, pkt_size, i;
390 	struct tcphdr *tcph;
391 	int flag[2];
392 
393 	payload_len = PAYLOAD_LEN * (psh || cwr);
394 	pkt_size = total_hdr_len + payload_len;
395 	flag[0] = NUM_PACKETS / 2;
396 	flag[1] = NUM_PACKETS / 2 - 1;
397 
398 	/* Create and configure packets with flags
399 	 */
400 	for (i = 0; i < 2; i++) {
401 		if (flag[i] > 0) {
402 			create_packet(flag_buf[i], flag[i] * payload_len, 0,
403 				      payload_len, 0);
404 			tcph = (struct tcphdr *)(flag_buf[i] + tcp_offset);
405 			set_flags(tcph, payload_len, psh, syn, rst, urg, cwr);
406 		}
407 	}
408 
409 	for (i = 0; i < NUM_PACKETS + 1; i++) {
410 		if (i == flag[0]) {
411 			write_packet(fd, flag_buf[0], pkt_size, daddr);
412 			continue;
413 		} else if (i == flag[1] && cwr) {
414 			write_packet(fd, flag_buf[1], pkt_size, daddr);
415 			continue;
416 		}
417 		create_packet(buf, i * PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
418 		write_packet(fd, buf, total_hdr_len + PAYLOAD_LEN, daddr);
419 	}
420 }
421 
422 /* Test for data of same length, smaller than previous
423  * and of different lengths
424  */
425 static void send_data_pkts(int fd, struct sockaddr_ll *daddr,
426 			   int payload_len1, int payload_len2)
427 {
428 	static char buf[ETH_HLEN + IP_MAXPACKET];
429 
430 	create_packet(buf, 0, 0, payload_len1, 0);
431 	write_packet(fd, buf, total_hdr_len + payload_len1, daddr);
432 	create_packet(buf, payload_len1, 0, payload_len2, 0);
433 	write_packet(fd, buf, total_hdr_len + payload_len2, daddr);
434 }
435 
436 /* If incoming segments make tracked segment length exceed
437  * legal IP datagram length, do not coalesce
438  */
439 static void send_large(int fd, struct sockaddr_ll *daddr, int remainder)
440 {
441 	static char pkts[NUM_LARGE_PKT][TOTAL_HDR_LEN + MSS];
442 	static char last[TOTAL_HDR_LEN + MSS];
443 	static char new_seg[TOTAL_HDR_LEN + MSS];
444 	int i;
445 
446 	for (i = 0; i < NUM_LARGE_PKT; i++)
447 		create_packet(pkts[i], i * MSS, 0, MSS, 0);
448 	create_packet(last, NUM_LARGE_PKT * MSS, 0, remainder, 0);
449 	create_packet(new_seg, (NUM_LARGE_PKT + 1) * MSS, 0, remainder, 0);
450 
451 	for (i = 0; i < NUM_LARGE_PKT; i++)
452 		write_packet(fd, pkts[i], total_hdr_len + MSS, daddr);
453 	write_packet(fd, last, total_hdr_len + remainder, daddr);
454 	write_packet(fd, new_seg, total_hdr_len + remainder, daddr);
455 }
456 
457 /* Pure acks and dup acks don't coalesce */
458 static void send_ack(int fd, struct sockaddr_ll *daddr)
459 {
460 	static char buf[MAX_HDR_LEN];
461 
462 	create_packet(buf, 0, 0, 0, 0);
463 	write_packet(fd, buf, total_hdr_len, daddr);
464 	write_packet(fd, buf, total_hdr_len, daddr);
465 	create_packet(buf, 0, 1, 0, 0);
466 	write_packet(fd, buf, total_hdr_len, daddr);
467 }
468 
469 static void recompute_packet(char *buf, char *no_ext, int extlen)
470 {
471 	struct tcphdr *tcphdr = (struct tcphdr *)(buf + tcp_offset);
472 	struct ipv6hdr *ip6h = (struct ipv6hdr *)(buf + ETH_HLEN);
473 	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
474 
475 	memmove(buf, no_ext, total_hdr_len);
476 	memmove(buf + total_hdr_len + extlen,
477 		no_ext + total_hdr_len, PAYLOAD_LEN);
478 
479 	tcphdr->doff = tcphdr->doff + (extlen / 4);
480 	tcphdr->check = 0;
481 	tcphdr->check = tcp_checksum(tcphdr, PAYLOAD_LEN + extlen);
482 	if (proto == PF_INET) {
483 		iph->tot_len = htons(ntohs(iph->tot_len) + extlen);
484 		iph->check = 0;
485 		iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
486 
487 		if (ipip) {
488 			iph += 1;
489 			iph->tot_len = htons(ntohs(iph->tot_len) + extlen);
490 			iph->check = 0;
491 			iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
492 		}
493 	} else {
494 		ip6h->payload_len = htons(ntohs(ip6h->payload_len) + extlen);
495 	}
496 }
497 
498 static void tcp_write_options(char *buf, int kind, int ts)
499 {
500 	struct tcp_option_ts {
501 		uint8_t kind;
502 		uint8_t len;
503 		uint32_t tsval;
504 		uint32_t tsecr;
505 	} *opt_ts = (void *)buf;
506 	struct tcp_option_window {
507 		uint8_t kind;
508 		uint8_t len;
509 		uint8_t shift;
510 	} *opt_window = (void *)buf;
511 
512 	switch (kind) {
513 	case TCPOPT_NOP:
514 		buf[0] = TCPOPT_NOP;
515 		break;
516 	case TCPOPT_WINDOW:
517 		memset(opt_window, 0, sizeof(struct tcp_option_window));
518 		opt_window->kind = TCPOPT_WINDOW;
519 		opt_window->len = TCPOLEN_WINDOW;
520 		opt_window->shift = 0;
521 		break;
522 	case TCPOPT_TIMESTAMP:
523 		memset(opt_ts, 0, sizeof(struct tcp_option_ts));
524 		opt_ts->kind = TCPOPT_TIMESTAMP;
525 		opt_ts->len = TCPOLEN_TIMESTAMP;
526 		opt_ts->tsval = ts;
527 		opt_ts->tsecr = 0;
528 		break;
529 	default:
530 		error(1, 0, "unimplemented TCP option");
531 		break;
532 	}
533 }
534 
535 /* TCP with options is always a permutation of {TS, NOP, NOP}.
536  * Implement different orders to verify coalescing stops.
537  */
538 static void add_standard_tcp_options(char *buf, char *no_ext, int ts, int order)
539 {
540 	switch (order) {
541 	case 0:
542 		tcp_write_options(buf + total_hdr_len, TCPOPT_NOP, 0);
543 		tcp_write_options(buf + total_hdr_len + 1, TCPOPT_NOP, 0);
544 		tcp_write_options(buf + total_hdr_len + 2 /* two NOP opts */,
545 				  TCPOPT_TIMESTAMP, ts);
546 		break;
547 	case 1:
548 		tcp_write_options(buf + total_hdr_len, TCPOPT_NOP, 0);
549 		tcp_write_options(buf + total_hdr_len + 1,
550 				  TCPOPT_TIMESTAMP, ts);
551 		tcp_write_options(buf + total_hdr_len + 1 + TCPOLEN_TIMESTAMP,
552 				  TCPOPT_NOP, 0);
553 		break;
554 	case 2:
555 		tcp_write_options(buf + total_hdr_len, TCPOPT_TIMESTAMP, ts);
556 		tcp_write_options(buf + total_hdr_len + TCPOLEN_TIMESTAMP + 1,
557 				  TCPOPT_NOP, 0);
558 		tcp_write_options(buf + total_hdr_len + TCPOLEN_TIMESTAMP + 2,
559 				  TCPOPT_NOP, 0);
560 		break;
561 	default:
562 		error(1, 0, "unknown order");
563 		break;
564 	}
565 	recompute_packet(buf, no_ext, TCPOLEN_TSTAMP_APPA);
566 }
567 
568 /* Packets with invalid checksum don't coalesce. */
569 static void send_changed_checksum(int fd, struct sockaddr_ll *daddr)
570 {
571 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
572 	struct tcphdr *tcph = (struct tcphdr *)(buf + tcp_offset);
573 	int pkt_size = total_hdr_len + PAYLOAD_LEN;
574 
575 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
576 	write_packet(fd, buf, pkt_size, daddr);
577 
578 	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
579 	tcph->check = tcph->check - 1;
580 	write_packet(fd, buf, pkt_size, daddr);
581 }
582 
583  /* Packets with non-consecutive sequence number don't coalesce.*/
584 static void send_changed_seq(int fd, struct sockaddr_ll *daddr)
585 {
586 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
587 	struct tcphdr *tcph = (struct tcphdr *)(buf + tcp_offset);
588 	int pkt_size = total_hdr_len + PAYLOAD_LEN;
589 
590 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
591 	write_packet(fd, buf, pkt_size, daddr);
592 
593 	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
594 	tcph->seq = ntohl(htonl(tcph->seq) + 1);
595 	tcph->check = 0;
596 	tcph->check = tcp_checksum(tcph, PAYLOAD_LEN);
597 	write_packet(fd, buf, pkt_size, daddr);
598 }
599 
600  /* Packet with different timestamp option or different timestamps
601   * don't coalesce.
602   */
603 static void send_changed_ts(int fd, struct sockaddr_ll *daddr)
604 {
605 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
606 	static char extpkt[sizeof(buf) + TCPOLEN_TSTAMP_APPA];
607 	int pkt_size = total_hdr_len + PAYLOAD_LEN + TCPOLEN_TSTAMP_APPA;
608 
609 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
610 	add_standard_tcp_options(extpkt, buf, 0, 0);
611 	write_packet(fd, extpkt, pkt_size, daddr);
612 
613 	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
614 	add_standard_tcp_options(extpkt, buf, 0, 0);
615 	write_packet(fd, extpkt, pkt_size, daddr);
616 
617 	create_packet(buf, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
618 	add_standard_tcp_options(extpkt, buf, 100, 0);
619 	write_packet(fd, extpkt, pkt_size, daddr);
620 
621 	create_packet(buf, PAYLOAD_LEN * 3, 0, PAYLOAD_LEN, 0);
622 	add_standard_tcp_options(extpkt, buf, 100, 1);
623 	write_packet(fd, extpkt, pkt_size, daddr);
624 
625 	create_packet(buf, PAYLOAD_LEN * 4, 0, PAYLOAD_LEN, 0);
626 	add_standard_tcp_options(extpkt, buf, 100, 2);
627 	write_packet(fd, extpkt, pkt_size, daddr);
628 }
629 
630 /* Packet with different tcp options don't coalesce. */
631 static void send_diff_opt(int fd, struct sockaddr_ll *daddr)
632 {
633 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
634 	static char extpkt1[sizeof(buf) + TCPOLEN_TSTAMP_APPA];
635 	static char extpkt2[sizeof(buf) + TCPOLEN_MAXSEG];
636 	int extpkt1_size = total_hdr_len + PAYLOAD_LEN + TCPOLEN_TSTAMP_APPA;
637 	int extpkt2_size = total_hdr_len + PAYLOAD_LEN + TCPOLEN_MAXSEG;
638 
639 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
640 	add_standard_tcp_options(extpkt1, buf, 0, 0);
641 	write_packet(fd, extpkt1, extpkt1_size, daddr);
642 
643 	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
644 	add_standard_tcp_options(extpkt1, buf, 0, 0);
645 	write_packet(fd, extpkt1, extpkt1_size, daddr);
646 
647 	create_packet(buf, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
648 	tcp_write_options(extpkt2 + MAX_HDR_LEN, TCPOPT_NOP, 0);
649 	tcp_write_options(extpkt2 + MAX_HDR_LEN + 1, TCPOPT_WINDOW, 0);
650 	recompute_packet(extpkt2, buf, TCPOLEN_WINDOW + 1);
651 	write_packet(fd, extpkt2, extpkt2_size, daddr);
652 }
653 
654 static void add_ipv4_ts_option(void *buf, void *optpkt)
655 {
656 	struct ip_timestamp *ts = (struct ip_timestamp *)(optpkt + tcp_offset);
657 	int optlen = sizeof(struct ip_timestamp);
658 	struct iphdr *iph;
659 
660 	if (optlen % 4)
661 		error(1, 0, "ipv4 timestamp length is not a multiple of 4B");
662 
663 	ts->ipt_code = IPOPT_TS;
664 	ts->ipt_len = optlen;
665 	ts->ipt_ptr = 5;
666 	ts->ipt_flg = IPOPT_TS_TSONLY;
667 
668 	memcpy(optpkt, buf, tcp_offset);
669 	memcpy(optpkt + tcp_offset + optlen, buf + tcp_offset,
670 	       sizeof(struct tcphdr) + PAYLOAD_LEN);
671 
672 	iph = (struct iphdr *)(optpkt + ETH_HLEN);
673 	iph->ihl = 5 + (optlen / 4);
674 	iph->tot_len = htons(ntohs(iph->tot_len) + optlen);
675 	iph->check = 0;
676 	iph->check = checksum_fold(iph, sizeof(struct iphdr) + optlen, 0);
677 }
678 
679 static void add_ipv6_exthdr(void *buf, void *optpkt, __u8 exthdr_type, char *ext_payload)
680 {
681 	struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr *)(optpkt + tcp_offset);
682 	struct ipv6hdr *iph = (struct ipv6hdr *)(optpkt + ETH_HLEN);
683 	char *exthdr_payload_start = (char *)(exthdr + 1);
684 
685 	exthdr->hdrlen = 0;
686 	exthdr->nexthdr = IPPROTO_TCP;
687 
688 	memcpy(exthdr_payload_start, ext_payload, MIN_EXTHDR_SIZE - sizeof(*exthdr));
689 
690 	memcpy(optpkt, buf, tcp_offset);
691 	memcpy(optpkt + tcp_offset + MIN_EXTHDR_SIZE, buf + tcp_offset,
692 		sizeof(struct tcphdr) + PAYLOAD_LEN);
693 
694 	iph->nexthdr = exthdr_type;
695 	iph->payload_len = htons(ntohs(iph->payload_len) + MIN_EXTHDR_SIZE);
696 }
697 
698 static void fix_ip4_checksum(struct iphdr *iph)
699 {
700 	iph->check = 0;
701 	iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
702 }
703 
704 static void send_flush_id_case(int fd, struct sockaddr_ll *daddr,
705 			       enum flush_id_case tcase)
706 {
707 	static char buf1[MAX_HDR_LEN + PAYLOAD_LEN];
708 	static char buf2[MAX_HDR_LEN + PAYLOAD_LEN];
709 	static char buf3[MAX_HDR_LEN + PAYLOAD_LEN];
710 	bool send_three = false;
711 	struct iphdr *iph1;
712 	struct iphdr *iph2;
713 	struct iphdr *iph3;
714 
715 	iph1 = (struct iphdr *)(buf1 + ETH_HLEN);
716 	iph2 = (struct iphdr *)(buf2 + ETH_HLEN);
717 	iph3 = (struct iphdr *)(buf3 + ETH_HLEN);
718 
719 	create_packet(buf1, 0, 0, PAYLOAD_LEN, 0);
720 	create_packet(buf2, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
721 	create_packet(buf3, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
722 
723 	switch (tcase) {
724 	case FLUSH_ID_DF1_INC: /* DF=1, Incrementing - should coalesce */
725 		iph1->frag_off |= htons(IP_DF);
726 		iph1->id = htons(8);
727 
728 		iph2->frag_off |= htons(IP_DF);
729 		iph2->id = htons(9);
730 		break;
731 
732 	case FLUSH_ID_DF1_FIXED: /* DF=1, Fixed - should coalesce */
733 		iph1->frag_off |= htons(IP_DF);
734 		iph1->id = htons(8);
735 
736 		iph2->frag_off |= htons(IP_DF);
737 		iph2->id = htons(8);
738 		break;
739 
740 	case FLUSH_ID_DF0_INC: /* DF=0, Incrementing - should coalesce */
741 		iph1->frag_off &= ~htons(IP_DF);
742 		iph1->id = htons(8);
743 
744 		iph2->frag_off &= ~htons(IP_DF);
745 		iph2->id = htons(9);
746 		break;
747 
748 	case FLUSH_ID_DF0_FIXED: /* DF=0, Fixed - should coalesce */
749 		iph1->frag_off &= ~htons(IP_DF);
750 		iph1->id = htons(8);
751 
752 		iph2->frag_off &= ~htons(IP_DF);
753 		iph2->id = htons(8);
754 		break;
755 
756 	case FLUSH_ID_DF1_INC_FIXED: /* DF=1, two packets incrementing, and
757 				      * one fixed - should coalesce only the
758 				      * first two packets
759 				      */
760 		iph1->frag_off |= htons(IP_DF);
761 		iph1->id = htons(8);
762 
763 		iph2->frag_off |= htons(IP_DF);
764 		iph2->id = htons(9);
765 
766 		iph3->frag_off |= htons(IP_DF);
767 		iph3->id = htons(9);
768 		send_three = true;
769 		break;
770 
771 	case FLUSH_ID_DF1_FIXED_INC: /* DF=1, two packets fixed, and one
772 				      * incrementing - should coalesce only
773 				      * the first two packets
774 				      */
775 		iph1->frag_off |= htons(IP_DF);
776 		iph1->id = htons(8);
777 
778 		iph2->frag_off |= htons(IP_DF);
779 		iph2->id = htons(8);
780 
781 		iph3->frag_off |= htons(IP_DF);
782 		iph3->id = htons(9);
783 		send_three = true;
784 		break;
785 	}
786 
787 	fix_ip4_checksum(iph1);
788 	fix_ip4_checksum(iph2);
789 	write_packet(fd, buf1, total_hdr_len + PAYLOAD_LEN, daddr);
790 	write_packet(fd, buf2, total_hdr_len + PAYLOAD_LEN, daddr);
791 
792 	if (send_three) {
793 		fix_ip4_checksum(iph3);
794 		write_packet(fd, buf3, total_hdr_len + PAYLOAD_LEN, daddr);
795 	}
796 }
797 
798 static void send_ipv6_exthdr(int fd, struct sockaddr_ll *daddr, char *ext_data1, char *ext_data2)
799 {
800 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
801 	static char exthdr_pck[sizeof(buf) + MIN_EXTHDR_SIZE];
802 
803 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
804 	add_ipv6_exthdr(buf, exthdr_pck, IPPROTO_DSTOPTS, ext_data1);
805 	write_packet(fd, exthdr_pck, total_hdr_len + PAYLOAD_LEN + MIN_EXTHDR_SIZE, daddr);
806 
807 	create_packet(buf, PAYLOAD_LEN * 1, 0, PAYLOAD_LEN, 0);
808 	add_ipv6_exthdr(buf, exthdr_pck, IPPROTO_DSTOPTS, ext_data2);
809 	write_packet(fd, exthdr_pck, total_hdr_len + PAYLOAD_LEN + MIN_EXTHDR_SIZE, daddr);
810 }
811 
812 /* IPv4 options shouldn't coalesce */
813 static void send_ip_options(int fd, struct sockaddr_ll *daddr)
814 {
815 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
816 	static char optpkt[sizeof(buf) + sizeof(struct ip_timestamp)];
817 	int optlen = sizeof(struct ip_timestamp);
818 	int pkt_size = total_hdr_len + PAYLOAD_LEN + optlen;
819 
820 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
821 	write_packet(fd, buf, total_hdr_len + PAYLOAD_LEN, daddr);
822 
823 	create_packet(buf, PAYLOAD_LEN * 1, 0, PAYLOAD_LEN, 0);
824 	add_ipv4_ts_option(buf, optpkt);
825 	write_packet(fd, optpkt, pkt_size, daddr);
826 
827 	create_packet(buf, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
828 	write_packet(fd, buf, total_hdr_len + PAYLOAD_LEN, daddr);
829 }
830 
831 /*  IPv4 fragments shouldn't coalesce */
832 static void send_fragment4(int fd, struct sockaddr_ll *daddr)
833 {
834 	static char buf[IP_MAXPACKET];
835 	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
836 	int pkt_size = total_hdr_len + PAYLOAD_LEN;
837 
838 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
839 	write_packet(fd, buf, pkt_size, daddr);
840 
841 	/* Once fragmented, packet would retain the total_len.
842 	 * Tcp header is prepared as if rest of data is in follow-up frags,
843 	 * but follow up frags aren't actually sent.
844 	 */
845 	memset(buf + total_hdr_len, 'a', PAYLOAD_LEN * 2);
846 	fill_transportlayer(buf + tcp_offset, PAYLOAD_LEN, 0, PAYLOAD_LEN * 2, 0);
847 	fill_networklayer(buf + ETH_HLEN, PAYLOAD_LEN, IPPROTO_TCP);
848 	fill_datalinklayer(buf);
849 
850 	iph->frag_off = htons(0x6000); // DF = 1, MF = 1
851 	iph->check = 0;
852 	iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
853 	write_packet(fd, buf, pkt_size, daddr);
854 }
855 
856 /* IPv4 packets with different ttl don't coalesce.*/
857 static void send_changed_ttl(int fd, struct sockaddr_ll *daddr)
858 {
859 	int pkt_size = total_hdr_len + PAYLOAD_LEN;
860 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
861 	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
862 
863 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
864 	write_packet(fd, buf, pkt_size, daddr);
865 
866 	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
867 	iph->ttl = 7;
868 	iph->check = 0;
869 	iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
870 	write_packet(fd, buf, pkt_size, daddr);
871 }
872 
873 /* Packets with different tos don't coalesce.*/
874 static void send_changed_tos(int fd, struct sockaddr_ll *daddr)
875 {
876 	int pkt_size = total_hdr_len + PAYLOAD_LEN;
877 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
878 	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
879 	struct ipv6hdr *ip6h = (struct ipv6hdr *)(buf + ETH_HLEN);
880 
881 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
882 	write_packet(fd, buf, pkt_size, daddr);
883 
884 	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
885 	if (proto == PF_INET) {
886 		iph->tos = 1;
887 		iph->check = 0;
888 		iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
889 	} else if (proto == PF_INET6) {
890 		ip6h->priority = 0xf;
891 	}
892 	write_packet(fd, buf, pkt_size, daddr);
893 }
894 
895 /* Packets with different ECN don't coalesce.*/
896 static void send_changed_ECN(int fd, struct sockaddr_ll *daddr)
897 {
898 	int pkt_size = total_hdr_len + PAYLOAD_LEN;
899 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
900 	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
901 
902 	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
903 	write_packet(fd, buf, pkt_size, daddr);
904 
905 	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
906 	if (proto == PF_INET) {
907 		buf[ETH_HLEN + 1] ^= 0x2; // ECN set to 10
908 		iph->check = 0;
909 		iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
910 	} else {
911 		buf[ETH_HLEN + 1] ^= 0x20; // ECN set to 10
912 	}
913 	write_packet(fd, buf, pkt_size, daddr);
914 }
915 
916 /* IPv6 fragments and packets with extensions don't coalesce.*/
917 static void send_fragment6(int fd, struct sockaddr_ll *daddr)
918 {
919 	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
920 	static char extpkt[MAX_HDR_LEN + PAYLOAD_LEN +
921 			   sizeof(struct ip6_frag)];
922 	struct ipv6hdr *ip6h = (struct ipv6hdr *)(buf + ETH_HLEN);
923 	struct ip6_frag *frag = (void *)(extpkt + tcp_offset);
924 	int extlen = sizeof(struct ip6_frag);
925 	int bufpkt_len = total_hdr_len + PAYLOAD_LEN;
926 	int extpkt_len = bufpkt_len + extlen;
927 	int i;
928 
929 	for (i = 0; i < 2; i++) {
930 		create_packet(buf, PAYLOAD_LEN * i, 0, PAYLOAD_LEN, 0);
931 		write_packet(fd, buf, bufpkt_len, daddr);
932 	}
933 	sleep(1);
934 	create_packet(buf, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
935 	memset(extpkt, 0, extpkt_len);
936 
937 	ip6h->nexthdr = IPPROTO_FRAGMENT;
938 	ip6h->payload_len = htons(ntohs(ip6h->payload_len) + extlen);
939 	frag->ip6f_nxt = IPPROTO_TCP;
940 
941 	memcpy(extpkt, buf, tcp_offset);
942 	memcpy(extpkt + tcp_offset + extlen, buf + tcp_offset,
943 	       sizeof(struct tcphdr) + PAYLOAD_LEN);
944 	write_packet(fd, extpkt, extpkt_len, daddr);
945 
946 	create_packet(buf, PAYLOAD_LEN * 3, 0, PAYLOAD_LEN, 0);
947 	write_packet(fd, buf, bufpkt_len, daddr);
948 }
949 
950 static void bind_packetsocket(int fd)
951 {
952 	struct sockaddr_ll daddr = {};
953 
954 	daddr.sll_family = AF_PACKET;
955 	daddr.sll_protocol = ethhdr_proto;
956 	daddr.sll_ifindex = if_nametoindex(ifname);
957 	if (daddr.sll_ifindex == 0)
958 		error(1, errno, "if_nametoindex");
959 
960 	if (bind(fd, (void *)&daddr, sizeof(daddr)) < 0)
961 		error(1, errno, "could not bind socket");
962 }
963 
964 static void set_timeout(int fd)
965 {
966 	struct timeval timeout;
967 
968 	timeout.tv_sec = 3;
969 	timeout.tv_usec = 0;
970 	if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout,
971 		       sizeof(timeout)) < 0)
972 		error(1, errno, "cannot set timeout, setsockopt failed");
973 }
974 
975 static void set_rcvbuf(int fd)
976 {
977 	int bufsize = 1 * 1024 * 1024; /* 1 MB */
978 
979 	if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &bufsize, sizeof(bufsize)))
980 		error(1, errno, "cannot set rcvbuf size, setsockopt failed");
981 }
982 
983 static void recv_error(int fd, int rcv_errno)
984 {
985 	struct tpacket_stats stats;
986 	socklen_t len;
987 
988 	len = sizeof(stats);
989 	if (getsockopt(fd, SOL_PACKET, PACKET_STATISTICS, &stats, &len))
990 		error(1, errno, "can't get stats");
991 
992 	fprintf(stderr, "Socket stats: packets=%u, drops=%u\n",
993 		stats.tp_packets, stats.tp_drops);
994 	error(1, rcv_errno, "could not receive");
995 }
996 
997 static void check_recv_pkts(int fd, int *correct_payload,
998 			    int correct_num_pkts)
999 {
1000 	static char buffer[IP_MAXPACKET + ETH_HLEN + 1];
1001 	struct iphdr *iph = (struct iphdr *)(buffer + ETH_HLEN);
1002 	struct ipv6hdr *ip6h = (struct ipv6hdr *)(buffer + ETH_HLEN);
1003 	struct tcphdr *tcph;
1004 	bool bad_packet = false;
1005 	int tcp_ext_len = 0;
1006 	int ip_ext_len = 0;
1007 	int pkt_size = -1;
1008 	int data_len = 0;
1009 	int num_pkt = 0;
1010 	int i;
1011 
1012 	vlog("Expected {");
1013 	for (i = 0; i < correct_num_pkts; i++)
1014 		vlog("%d ", correct_payload[i]);
1015 	vlog("}, Total %d packets\nReceived {", correct_num_pkts);
1016 
1017 	while (1) {
1018 		ip_ext_len = 0;
1019 		pkt_size = recv(fd, buffer, IP_MAXPACKET + ETH_HLEN + 1, 0);
1020 		if (pkt_size < 0)
1021 			recv_error(fd, errno);
1022 
1023 		if (iph->version == 4)
1024 			ip_ext_len = (iph->ihl - 5) * 4;
1025 		else if (ip6h->version == 6 && ip6h->nexthdr != IPPROTO_TCP)
1026 			ip_ext_len = MIN_EXTHDR_SIZE;
1027 
1028 		tcph = (struct tcphdr *)(buffer + tcp_offset + ip_ext_len);
1029 
1030 		if (tcph->fin)
1031 			break;
1032 
1033 		tcp_ext_len = (tcph->doff - 5) * 4;
1034 		data_len = pkt_size - total_hdr_len - tcp_ext_len - ip_ext_len;
1035 		/* Min ethernet frame payload is 46(ETH_ZLEN - ETH_HLEN) by RFC 802.3.
1036 		 * Ipv4/tcp packets without at least 6 bytes of data will be padded.
1037 		 * Packet sockets are protocol agnostic, and will not trim the padding.
1038 		 */
1039 		if (pkt_size == ETH_ZLEN && iph->version == 4) {
1040 			data_len = ntohs(iph->tot_len)
1041 				- sizeof(struct tcphdr) - sizeof(struct iphdr);
1042 		}
1043 		vlog("%d ", data_len);
1044 		if (data_len != correct_payload[num_pkt]) {
1045 			vlog("[!=%d]", correct_payload[num_pkt]);
1046 			bad_packet = true;
1047 		}
1048 		num_pkt++;
1049 	}
1050 	vlog("}, Total %d packets.\n", num_pkt);
1051 	if (num_pkt != correct_num_pkts)
1052 		error(1, 0, "incorrect number of packets");
1053 	if (bad_packet)
1054 		error(1, 0, "incorrect packet geometry");
1055 
1056 	printf("Test succeeded\n\n");
1057 }
1058 
1059 static void gro_sender(void)
1060 {
1061 	const int fin_delay_us = 100 * 1000;
1062 	static char fin_pkt[MAX_HDR_LEN];
1063 	struct sockaddr_ll daddr = {};
1064 	int txfd = -1;
1065 
1066 	txfd = socket(PF_PACKET, SOCK_RAW, IPPROTO_RAW);
1067 	if (txfd < 0)
1068 		error(1, errno, "socket creation");
1069 
1070 	memset(&daddr, 0, sizeof(daddr));
1071 	daddr.sll_ifindex = if_nametoindex(ifname);
1072 	if (daddr.sll_ifindex == 0)
1073 		error(1, errno, "if_nametoindex");
1074 	daddr.sll_family = AF_PACKET;
1075 	memcpy(daddr.sll_addr, dst_mac, ETH_ALEN);
1076 	daddr.sll_halen = ETH_ALEN;
1077 	create_packet(fin_pkt, PAYLOAD_LEN * 2, 0, 0, 1);
1078 
1079 	/* data sub-tests */
1080 	if (strcmp(testname, "data_same") == 0) {
1081 		send_data_pkts(txfd, &daddr, PAYLOAD_LEN, PAYLOAD_LEN);
1082 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1083 	} else if (strcmp(testname, "data_lrg_sml") == 0) {
1084 		send_data_pkts(txfd, &daddr, PAYLOAD_LEN, PAYLOAD_LEN / 2);
1085 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1086 	} else if (strcmp(testname, "data_sml_lrg") == 0) {
1087 		send_data_pkts(txfd, &daddr, PAYLOAD_LEN / 2, PAYLOAD_LEN);
1088 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1089 
1090 	/* ack test */
1091 	} else if (strcmp(testname, "ack") == 0) {
1092 		send_ack(txfd, &daddr);
1093 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1094 
1095 	/* flags sub-tests */
1096 	} else if (strcmp(testname, "flags_psh") == 0) {
1097 		send_flags(txfd, &daddr, 1, 0, 0, 0, 0);
1098 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1099 	} else if (strcmp(testname, "flags_syn") == 0) {
1100 		send_flags(txfd, &daddr, 0, 1, 0, 0, 0);
1101 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1102 	} else if (strcmp(testname, "flags_rst") == 0) {
1103 		send_flags(txfd, &daddr, 0, 0, 1, 0, 0);
1104 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1105 	} else if (strcmp(testname, "flags_urg") == 0) {
1106 		send_flags(txfd, &daddr, 0, 0, 0, 1, 0);
1107 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1108 	} else if (strcmp(testname, "flags_cwr") == 0) {
1109 		send_flags(txfd, &daddr, 0, 0, 0, 0, 1);
1110 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1111 
1112 	/* tcp sub-tests */
1113 	} else if (strcmp(testname, "tcp_csum") == 0) {
1114 		send_changed_checksum(txfd, &daddr);
1115 		usleep(fin_delay_us);
1116 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1117 	} else if (strcmp(testname, "tcp_seq") == 0) {
1118 		send_changed_seq(txfd, &daddr);
1119 		usleep(fin_delay_us);
1120 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1121 	} else if (strcmp(testname, "tcp_ts") == 0) {
1122 		send_changed_ts(txfd, &daddr);
1123 		usleep(fin_delay_us);
1124 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1125 	} else if (strcmp(testname, "tcp_opt") == 0) {
1126 		send_diff_opt(txfd, &daddr);
1127 		usleep(fin_delay_us);
1128 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1129 
1130 	/* ip sub-tests - shared between IPv4 and IPv6 */
1131 	} else if (strcmp(testname, "ip_ecn") == 0) {
1132 		send_changed_ECN(txfd, &daddr);
1133 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1134 	} else if (strcmp(testname, "ip_tos") == 0) {
1135 		send_changed_tos(txfd, &daddr);
1136 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1137 
1138 	/* ip sub-tests - IPv4 only */
1139 	} else if (strcmp(testname, "ip_ttl") == 0) {
1140 		send_changed_ttl(txfd, &daddr);
1141 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1142 	} else if (strcmp(testname, "ip_opt") == 0) {
1143 		send_ip_options(txfd, &daddr);
1144 		usleep(fin_delay_us);
1145 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1146 	} else if (strcmp(testname, "ip_frag4") == 0) {
1147 		send_fragment4(txfd, &daddr);
1148 		usleep(fin_delay_us);
1149 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1150 	} else if (strcmp(testname, "ip_id_df1_inc") == 0) {
1151 		send_flush_id_case(txfd, &daddr, FLUSH_ID_DF1_INC);
1152 		usleep(fin_delay_us);
1153 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1154 	} else if (strcmp(testname, "ip_id_df1_fixed") == 0) {
1155 		send_flush_id_case(txfd, &daddr, FLUSH_ID_DF1_FIXED);
1156 		usleep(fin_delay_us);
1157 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1158 	} else if (strcmp(testname, "ip_id_df0_inc") == 0) {
1159 		send_flush_id_case(txfd, &daddr, FLUSH_ID_DF0_INC);
1160 		usleep(fin_delay_us);
1161 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1162 	} else if (strcmp(testname, "ip_id_df0_fixed") == 0) {
1163 		send_flush_id_case(txfd, &daddr, FLUSH_ID_DF0_FIXED);
1164 		usleep(fin_delay_us);
1165 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1166 	} else if (strcmp(testname, "ip_id_df1_inc_fixed") == 0) {
1167 		send_flush_id_case(txfd, &daddr, FLUSH_ID_DF1_INC_FIXED);
1168 		usleep(fin_delay_us);
1169 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1170 	} else if (strcmp(testname, "ip_id_df1_fixed_inc") == 0) {
1171 		send_flush_id_case(txfd, &daddr, FLUSH_ID_DF1_FIXED_INC);
1172 		usleep(fin_delay_us);
1173 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1174 
1175 	/* ip sub-tests - IPv6 only */
1176 	} else if (strcmp(testname, "ip_frag6") == 0) {
1177 		send_fragment6(txfd, &daddr);
1178 		usleep(fin_delay_us);
1179 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1180 	} else if (strcmp(testname, "ip_v6ext_same") == 0) {
1181 		send_ipv6_exthdr(txfd, &daddr, EXT_PAYLOAD_1, EXT_PAYLOAD_1);
1182 		usleep(fin_delay_us);
1183 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1184 	} else if (strcmp(testname, "ip_v6ext_diff") == 0) {
1185 		send_ipv6_exthdr(txfd, &daddr, EXT_PAYLOAD_1, EXT_PAYLOAD_2);
1186 		usleep(fin_delay_us);
1187 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1188 
1189 	/* large sub-tests */
1190 	} else if (strcmp(testname, "large_max") == 0) {
1191 		int offset = (proto == PF_INET && !ipip) ? 20 : 0;
1192 		int remainder = (MAX_PAYLOAD + offset) % MSS;
1193 
1194 		send_large(txfd, &daddr, remainder);
1195 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1196 	} else if (strcmp(testname, "large_rem") == 0) {
1197 		int offset = (proto == PF_INET && !ipip) ? 20 : 0;
1198 		int remainder = (MAX_PAYLOAD + offset) % MSS;
1199 
1200 		send_large(txfd, &daddr, remainder + 1);
1201 		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
1202 	} else {
1203 		error(1, 0, "Unknown testcase: %s", testname);
1204 	}
1205 
1206 	if (close(txfd))
1207 		error(1, errno, "socket close");
1208 }
1209 
1210 static void gro_receiver(void)
1211 {
1212 	static int correct_payload[NUM_PACKETS];
1213 	int rxfd = -1;
1214 
1215 	rxfd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_NONE));
1216 	if (rxfd < 0)
1217 		error(1, 0, "socket creation");
1218 	setup_sock_filter(rxfd);
1219 	set_timeout(rxfd);
1220 	set_rcvbuf(rxfd);
1221 	bind_packetsocket(rxfd);
1222 
1223 	ksft_ready();
1224 
1225 	memset(correct_payload, 0, sizeof(correct_payload));
1226 
1227 	/* data sub-tests */
1228 	if (strcmp(testname, "data_same") == 0) {
1229 		printf("pure data packet of same size: ");
1230 		correct_payload[0] = PAYLOAD_LEN * 2;
1231 		check_recv_pkts(rxfd, correct_payload, 1);
1232 	} else if (strcmp(testname, "data_lrg_sml") == 0) {
1233 		printf("large data packets followed by a smaller one: ");
1234 		correct_payload[0] = PAYLOAD_LEN * 1.5;
1235 		check_recv_pkts(rxfd, correct_payload, 1);
1236 	} else if (strcmp(testname, "data_sml_lrg") == 0) {
1237 		printf("small data packets followed by a larger one: ");
1238 		correct_payload[0] = PAYLOAD_LEN / 2;
1239 		correct_payload[1] = PAYLOAD_LEN;
1240 		check_recv_pkts(rxfd, correct_payload, 2);
1241 
1242 	/* ack test */
1243 	} else if (strcmp(testname, "ack") == 0) {
1244 		printf("duplicate ack and pure ack: ");
1245 		check_recv_pkts(rxfd, correct_payload, 3);
1246 
1247 	/* flags sub-tests */
1248 	} else if (strcmp(testname, "flags_psh") == 0) {
1249 		correct_payload[0] = PAYLOAD_LEN * 3;
1250 		correct_payload[1] = PAYLOAD_LEN * 2;
1251 		printf("psh flag ends coalescing: ");
1252 		check_recv_pkts(rxfd, correct_payload, 2);
1253 	} else if (strcmp(testname, "flags_syn") == 0) {
1254 		correct_payload[0] = PAYLOAD_LEN * 2;
1255 		correct_payload[1] = 0;
1256 		correct_payload[2] = PAYLOAD_LEN * 2;
1257 		printf("syn flag ends coalescing: ");
1258 		check_recv_pkts(rxfd, correct_payload, 3);
1259 	} else if (strcmp(testname, "flags_rst") == 0) {
1260 		correct_payload[0] = PAYLOAD_LEN * 2;
1261 		correct_payload[1] = 0;
1262 		correct_payload[2] = PAYLOAD_LEN * 2;
1263 		printf("rst flag ends coalescing: ");
1264 		check_recv_pkts(rxfd, correct_payload, 3);
1265 	} else if (strcmp(testname, "flags_urg") == 0) {
1266 		correct_payload[0] = PAYLOAD_LEN * 2;
1267 		correct_payload[1] = 0;
1268 		correct_payload[2] = PAYLOAD_LEN * 2;
1269 		printf("urg flag ends coalescing: ");
1270 		check_recv_pkts(rxfd, correct_payload, 3);
1271 	} else if (strcmp(testname, "flags_cwr") == 0) {
1272 		correct_payload[0] = PAYLOAD_LEN;
1273 		correct_payload[1] = PAYLOAD_LEN * 2;
1274 		correct_payload[2] = PAYLOAD_LEN * 2;
1275 		printf("cwr flag ends coalescing: ");
1276 		check_recv_pkts(rxfd, correct_payload, 3);
1277 
1278 	/* tcp sub-tests */
1279 	} else if (strcmp(testname, "tcp_csum") == 0) {
1280 		correct_payload[0] = PAYLOAD_LEN;
1281 		correct_payload[1] = PAYLOAD_LEN;
1282 		printf("changed checksum does not coalesce: ");
1283 		check_recv_pkts(rxfd, correct_payload, 2);
1284 	} else if (strcmp(testname, "tcp_seq") == 0) {
1285 		correct_payload[0] = PAYLOAD_LEN;
1286 		correct_payload[1] = PAYLOAD_LEN;
1287 		printf("Wrong Seq number doesn't coalesce: ");
1288 		check_recv_pkts(rxfd, correct_payload, 2);
1289 	} else if (strcmp(testname, "tcp_ts") == 0) {
1290 		correct_payload[0] = PAYLOAD_LEN * 2;
1291 		correct_payload[1] = PAYLOAD_LEN;
1292 		correct_payload[2] = PAYLOAD_LEN;
1293 		correct_payload[3] = PAYLOAD_LEN;
1294 		printf("Different timestamp doesn't coalesce: ");
1295 		check_recv_pkts(rxfd, correct_payload, 4);
1296 	} else if (strcmp(testname, "tcp_opt") == 0) {
1297 		correct_payload[0] = PAYLOAD_LEN * 2;
1298 		correct_payload[1] = PAYLOAD_LEN;
1299 		printf("Different options doesn't coalesce: ");
1300 		check_recv_pkts(rxfd, correct_payload, 2);
1301 
1302 	/* ip sub-tests - shared between IPv4 and IPv6 */
1303 	} else if (strcmp(testname, "ip_ecn") == 0) {
1304 		correct_payload[0] = PAYLOAD_LEN;
1305 		correct_payload[1] = PAYLOAD_LEN;
1306 		printf("different ECN doesn't coalesce: ");
1307 		check_recv_pkts(rxfd, correct_payload, 2);
1308 	} else if (strcmp(testname, "ip_tos") == 0) {
1309 		correct_payload[0] = PAYLOAD_LEN;
1310 		correct_payload[1] = PAYLOAD_LEN;
1311 		printf("different tos doesn't coalesce: ");
1312 		check_recv_pkts(rxfd, correct_payload, 2);
1313 
1314 	/* ip sub-tests - IPv4 only */
1315 	} else if (strcmp(testname, "ip_ttl") == 0) {
1316 		correct_payload[0] = PAYLOAD_LEN;
1317 		correct_payload[1] = PAYLOAD_LEN;
1318 		printf("different ttl doesn't coalesce: ");
1319 		check_recv_pkts(rxfd, correct_payload, 2);
1320 	} else if (strcmp(testname, "ip_opt") == 0) {
1321 		correct_payload[0] = PAYLOAD_LEN;
1322 		correct_payload[1] = PAYLOAD_LEN;
1323 		correct_payload[2] = PAYLOAD_LEN;
1324 		printf("ip options doesn't coalesce: ");
1325 		check_recv_pkts(rxfd, correct_payload, 3);
1326 	} else if (strcmp(testname, "ip_frag4") == 0) {
1327 		correct_payload[0] = PAYLOAD_LEN;
1328 		correct_payload[1] = PAYLOAD_LEN;
1329 		printf("fragmented ip4 doesn't coalesce: ");
1330 		check_recv_pkts(rxfd, correct_payload, 2);
1331 	} else if (strcmp(testname, "ip_id_df1_inc") == 0) {
1332 		printf("DF=1, Incrementing - should coalesce: ");
1333 		correct_payload[0] = PAYLOAD_LEN * 2;
1334 		check_recv_pkts(rxfd, correct_payload, 1);
1335 	} else if (strcmp(testname, "ip_id_df1_fixed") == 0) {
1336 		printf("DF=1, Fixed - should coalesce: ");
1337 		correct_payload[0] = PAYLOAD_LEN * 2;
1338 		check_recv_pkts(rxfd, correct_payload, 1);
1339 	} else if (strcmp(testname, "ip_id_df0_inc") == 0) {
1340 		printf("DF=0, Incrementing - should coalesce: ");
1341 		correct_payload[0] = PAYLOAD_LEN * 2;
1342 		check_recv_pkts(rxfd, correct_payload, 1);
1343 	} else if (strcmp(testname, "ip_id_df0_fixed") == 0) {
1344 		printf("DF=0, Fixed - should coalesce: ");
1345 		correct_payload[0] = PAYLOAD_LEN * 2;
1346 		check_recv_pkts(rxfd, correct_payload, 1);
1347 	} else if (strcmp(testname, "ip_id_df1_inc_fixed") == 0) {
1348 		printf("DF=1, 2 Incrementing and one fixed - should coalesce only first 2 packets: ");
1349 		correct_payload[0] = PAYLOAD_LEN * 2;
1350 		correct_payload[1] = PAYLOAD_LEN;
1351 		check_recv_pkts(rxfd, correct_payload, 2);
1352 	} else if (strcmp(testname, "ip_id_df1_fixed_inc") == 0) {
1353 		printf("DF=1, 2 Fixed and one incrementing - should coalesce only first 2 packets: ");
1354 		correct_payload[0] = PAYLOAD_LEN * 2;
1355 		correct_payload[1] = PAYLOAD_LEN;
1356 		check_recv_pkts(rxfd, correct_payload, 2);
1357 
1358 	/* ip sub-tests - IPv6 only */
1359 	} else if (strcmp(testname, "ip_frag6") == 0) {
1360 		/* GRO doesn't check for ipv6 hop limit when flushing.
1361 		 * Hence no corresponding test to the ipv4 case.
1362 		 */
1363 		printf("fragmented ip6 doesn't coalesce: ");
1364 		correct_payload[0] = PAYLOAD_LEN * 2;
1365 		correct_payload[1] = PAYLOAD_LEN;
1366 		correct_payload[2] = PAYLOAD_LEN;
1367 		check_recv_pkts(rxfd, correct_payload, 3);
1368 	} else if (strcmp(testname, "ip_v6ext_same") == 0) {
1369 		printf("ipv6 with ext header does coalesce: ");
1370 		correct_payload[0] = PAYLOAD_LEN * 2;
1371 		check_recv_pkts(rxfd, correct_payload, 1);
1372 	} else if (strcmp(testname, "ip_v6ext_diff") == 0) {
1373 		printf("ipv6 with ext header with different payloads doesn't coalesce: ");
1374 		correct_payload[0] = PAYLOAD_LEN;
1375 		correct_payload[1] = PAYLOAD_LEN;
1376 		check_recv_pkts(rxfd, correct_payload, 2);
1377 
1378 	/* large sub-tests */
1379 	} else if (strcmp(testname, "large_max") == 0) {
1380 		int offset = (proto == PF_INET && !ipip) ? 20 : 0;
1381 		int remainder = (MAX_PAYLOAD + offset) % MSS;
1382 
1383 		correct_payload[0] = (MAX_PAYLOAD + offset);
1384 		correct_payload[1] = remainder;
1385 		printf("Shouldn't coalesce if exceed IP max pkt size: ");
1386 		check_recv_pkts(rxfd, correct_payload, 2);
1387 	} else if (strcmp(testname, "large_rem") == 0) {
1388 		int offset = (proto == PF_INET && !ipip) ? 20 : 0;
1389 		int remainder = (MAX_PAYLOAD + offset) % MSS;
1390 
1391 		/* last segment sent individually, doesn't start new segment */
1392 		correct_payload[0] = (MAX_PAYLOAD + offset) - remainder;
1393 		correct_payload[1] = remainder + 1;
1394 		correct_payload[2] = remainder + 1;
1395 		printf("last segment sent individually: ");
1396 		check_recv_pkts(rxfd, correct_payload, 3);
1397 	} else {
1398 		error(1, 0, "Test case error: unknown testname %s", testname);
1399 	}
1400 
1401 	if (close(rxfd))
1402 		error(1, 0, "socket close");
1403 }
1404 
1405 static void parse_args(int argc, char **argv)
1406 {
1407 	static const struct option opts[] = {
1408 		{ "daddr", required_argument, NULL, 'd' },
1409 		{ "dmac", required_argument, NULL, 'D' },
1410 		{ "iface", required_argument, NULL, 'i' },
1411 		{ "ipv4", no_argument, NULL, '4' },
1412 		{ "ipv6", no_argument, NULL, '6' },
1413 		{ "ipip", no_argument, NULL, 'e' },
1414 		{ "rx", no_argument, NULL, 'r' },
1415 		{ "saddr", required_argument, NULL, 's' },
1416 		{ "smac", required_argument, NULL, 'S' },
1417 		{ "test", required_argument, NULL, 't' },
1418 		{ "verbose", no_argument, NULL, 'v' },
1419 		{ 0, 0, 0, 0 }
1420 	};
1421 	int c;
1422 
1423 	while ((c = getopt_long(argc, argv, "46d:D:ei:rs:S:t:v", opts, NULL)) != -1) {
1424 		switch (c) {
1425 		case '4':
1426 			proto = PF_INET;
1427 			ethhdr_proto = htons(ETH_P_IP);
1428 			break;
1429 		case '6':
1430 			proto = PF_INET6;
1431 			ethhdr_proto = htons(ETH_P_IPV6);
1432 			break;
1433 		case 'e':
1434 			ipip = true;
1435 			proto = PF_INET;
1436 			ethhdr_proto = htons(ETH_P_IP);
1437 			break;
1438 		case 'd':
1439 			addr4_dst = addr6_dst = optarg;
1440 			break;
1441 		case 'D':
1442 			dmac = optarg;
1443 			break;
1444 		case 'i':
1445 			ifname = optarg;
1446 			break;
1447 		case 'r':
1448 			tx_socket = false;
1449 			break;
1450 		case 's':
1451 			addr4_src = addr6_src = optarg;
1452 			break;
1453 		case 'S':
1454 			smac = optarg;
1455 			break;
1456 		case 't':
1457 			testname = optarg;
1458 			break;
1459 		case 'v':
1460 			verbose = true;
1461 			break;
1462 		default:
1463 			error(1, 0, "%s invalid option %c\n", __func__, c);
1464 			break;
1465 		}
1466 	}
1467 }
1468 
1469 int main(int argc, char **argv)
1470 {
1471 	parse_args(argc, argv);
1472 
1473 	if (ipip) {
1474 		tcp_offset = ETH_HLEN + sizeof(struct iphdr) * 2;
1475 		total_hdr_len = tcp_offset + sizeof(struct tcphdr);
1476 	} else if (proto == PF_INET) {
1477 		tcp_offset = ETH_HLEN + sizeof(struct iphdr);
1478 		total_hdr_len = tcp_offset + sizeof(struct tcphdr);
1479 	} else if (proto == PF_INET6) {
1480 		tcp_offset = ETH_HLEN + sizeof(struct ipv6hdr);
1481 		total_hdr_len = MAX_HDR_LEN;
1482 	} else {
1483 		error(1, 0, "Protocol family is not ipv4 or ipv6");
1484 	}
1485 
1486 	read_MAC(src_mac, smac);
1487 	read_MAC(dst_mac, dmac);
1488 
1489 	if (tx_socket) {
1490 		gro_sender();
1491 	} else {
1492 		/* Only the receiver exit status determines test success. */
1493 		gro_receiver();
1494 		fprintf(stderr, "Gro::%s test passed.\n", testname);
1495 	}
1496 
1497 	return 0;
1498 }
1499