1 // SPDX-License-Identifier: GPL-2.0 2 3 #define _GNU_SOURCE 4 5 #include <arpa/inet.h> 6 #include <errno.h> 7 #include <error.h> 8 #include <linux/in.h> 9 #include <netinet/ip.h> 10 #include <netinet/ip6.h> 11 #include <netinet/udp.h> 12 #include <stdbool.h> 13 #include <stdio.h> 14 #include <stdlib.h> 15 #include <string.h> 16 #include <time.h> 17 #include <unistd.h> 18 19 static bool cfg_do_ipv4; 20 static bool cfg_do_ipv6; 21 static bool cfg_verbose; 22 static bool cfg_overlap; 23 static bool cfg_permissive; 24 static unsigned short cfg_port = 9000; 25 26 const struct in_addr addr4 = { .s_addr = __constant_htonl(INADDR_LOOPBACK + 2) }; 27 const struct in6_addr addr6 = IN6ADDR_LOOPBACK_INIT; 28 29 #define IP4_HLEN (sizeof(struct iphdr)) 30 #define IP6_HLEN (sizeof(struct ip6_hdr)) 31 #define UDP_HLEN (sizeof(struct udphdr)) 32 33 /* IPv6 fragment header lenth. */ 34 #define FRAG_HLEN 8 35 36 static int payload_len; 37 static int max_frag_len; 38 39 #define MSG_LEN_MAX 10000 /* Max UDP payload length. */ 40 41 #define IP4_MF (1u << 13) /* IPv4 MF flag. */ 42 #define IP6_MF (1) /* IPv6 MF flag. */ 43 44 #define CSUM_MANGLED_0 (0xffff) 45 46 static uint8_t udp_payload[MSG_LEN_MAX]; 47 static uint8_t ip_frame[IP_MAXPACKET]; 48 static uint32_t ip_id = 0xabcd; 49 static int msg_counter; 50 static int frag_counter; 51 static unsigned int seed; 52 53 /* Receive a UDP packet. Validate it matches udp_payload. */ 54 static void recv_validate_udp(int fd_udp) 55 { 56 ssize_t ret; 57 static uint8_t recv_buff[MSG_LEN_MAX]; 58 59 ret = recv(fd_udp, recv_buff, payload_len, 0); 60 msg_counter++; 61 62 if (cfg_overlap) { 63 if (ret == -1 && (errno == ETIMEDOUT || errno == EAGAIN)) 64 return; /* OK */ 65 if (!cfg_permissive) { 66 if (ret != -1) 67 error(1, 0, "recv: expected timeout; got %d", 68 (int)ret); 69 error(1, errno, "recv: expected timeout: %d", errno); 70 } 71 } 72 73 if (ret == -1) 74 error(1, errno, "recv: payload_len = %d max_frag_len = %d", 75 payload_len, max_frag_len); 76 if (ret != payload_len) 77 error(1, 0, "recv: wrong size: %d vs %d", (int)ret, payload_len); 78 if (memcmp(udp_payload, recv_buff, payload_len)) 79 error(1, 0, "recv: wrong data"); 80 } 81 82 static uint32_t raw_checksum(uint8_t *buf, int len, uint32_t sum) 83 { 84 int i; 85 86 for (i = 0; i < (len & ~1U); i += 2) { 87 sum += (u_int16_t)ntohs(*((u_int16_t *)(buf + i))); 88 if (sum > 0xffff) 89 sum -= 0xffff; 90 } 91 92 if (i < len) { 93 sum += buf[i] << 8; 94 if (sum > 0xffff) 95 sum -= 0xffff; 96 } 97 98 return sum; 99 } 100 101 static uint16_t udp_checksum(struct ip *iphdr, struct udphdr *udphdr) 102 { 103 uint32_t sum = 0; 104 uint16_t res; 105 106 sum = raw_checksum((uint8_t *)&iphdr->ip_src, 2 * sizeof(iphdr->ip_src), 107 IPPROTO_UDP + (uint32_t)(UDP_HLEN + payload_len)); 108 sum = raw_checksum((uint8_t *)udphdr, UDP_HLEN, sum); 109 sum = raw_checksum((uint8_t *)udp_payload, payload_len, sum); 110 res = 0xffff & ~sum; 111 if (res) 112 return htons(res); 113 else 114 return CSUM_MANGLED_0; 115 } 116 117 static uint16_t udp6_checksum(struct ip6_hdr *iphdr, struct udphdr *udphdr) 118 { 119 uint32_t sum = 0; 120 uint16_t res; 121 122 sum = raw_checksum((uint8_t *)&iphdr->ip6_src, 2 * sizeof(iphdr->ip6_src), 123 IPPROTO_UDP); 124 sum = raw_checksum((uint8_t *)&udphdr->len, sizeof(udphdr->len), sum); 125 sum = raw_checksum((uint8_t *)udphdr, UDP_HLEN, sum); 126 sum = raw_checksum((uint8_t *)udp_payload, payload_len, sum); 127 res = 0xffff & ~sum; 128 if (res) 129 return htons(res); 130 else 131 return CSUM_MANGLED_0; 132 } 133 134 static void send_fragment(int fd_raw, struct sockaddr *addr, socklen_t alen, 135 int offset, bool ipv6) 136 { 137 int frag_len; 138 int res; 139 int payload_offset = offset > 0 ? offset - UDP_HLEN : 0; 140 uint8_t *frag_start = ipv6 ? ip_frame + IP6_HLEN + FRAG_HLEN : 141 ip_frame + IP4_HLEN; 142 143 if (offset == 0) { 144 struct udphdr udphdr; 145 udphdr.source = htons(cfg_port + 1); 146 udphdr.dest = htons(cfg_port); 147 udphdr.len = htons(UDP_HLEN + payload_len); 148 udphdr.check = 0; 149 if (ipv6) 150 udphdr.check = udp6_checksum((struct ip6_hdr *)ip_frame, &udphdr); 151 else 152 udphdr.check = udp_checksum((struct ip *)ip_frame, &udphdr); 153 memcpy(frag_start, &udphdr, UDP_HLEN); 154 } 155 156 if (ipv6) { 157 struct ip6_hdr *ip6hdr = (struct ip6_hdr *)ip_frame; 158 struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN); 159 if (payload_len - payload_offset <= max_frag_len && offset > 0) { 160 /* This is the last fragment. */ 161 frag_len = FRAG_HLEN + payload_len - payload_offset; 162 fraghdr->ip6f_offlg = htons(offset); 163 } else { 164 frag_len = FRAG_HLEN + max_frag_len; 165 fraghdr->ip6f_offlg = htons(offset | IP6_MF); 166 } 167 ip6hdr->ip6_plen = htons(frag_len); 168 if (offset == 0) 169 memcpy(frag_start + UDP_HLEN, udp_payload, 170 frag_len - FRAG_HLEN - UDP_HLEN); 171 else 172 memcpy(frag_start, udp_payload + payload_offset, 173 frag_len - FRAG_HLEN); 174 frag_len += IP6_HLEN; 175 } else { 176 struct ip *iphdr = (struct ip *)ip_frame; 177 if (payload_len - payload_offset <= max_frag_len && offset > 0) { 178 /* This is the last fragment. */ 179 frag_len = IP4_HLEN + payload_len - payload_offset; 180 iphdr->ip_off = htons(offset / 8); 181 } else { 182 frag_len = IP4_HLEN + max_frag_len; 183 iphdr->ip_off = htons(offset / 8 | IP4_MF); 184 } 185 iphdr->ip_len = htons(frag_len); 186 if (offset == 0) 187 memcpy(frag_start + UDP_HLEN, udp_payload, 188 frag_len - IP4_HLEN - UDP_HLEN); 189 else 190 memcpy(frag_start, udp_payload + payload_offset, 191 frag_len - IP4_HLEN); 192 } 193 194 res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen); 195 if (res < 0) 196 error(1, errno, "send_fragment"); 197 if (res != frag_len) 198 error(1, 0, "send_fragment: %d vs %d", res, frag_len); 199 200 frag_counter++; 201 } 202 203 static void send_udp_frags(int fd_raw, struct sockaddr *addr, 204 socklen_t alen, bool ipv6) 205 { 206 struct ip *iphdr = (struct ip *)ip_frame; 207 struct ip6_hdr *ip6hdr = (struct ip6_hdr *)ip_frame; 208 int res; 209 int offset; 210 int frag_len; 211 212 /* Send the UDP datagram using raw IP fragments: the 0th fragment 213 * has the UDP header; other fragments are pieces of udp_payload 214 * split in chunks of frag_len size. 215 * 216 * Odd fragments (1st, 3rd, 5th, etc.) are sent out first, then 217 * even fragments (0th, 2nd, etc.) are sent out. 218 */ 219 if (ipv6) { 220 struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN); 221 ((struct sockaddr_in6 *)addr)->sin6_port = 0; 222 memset(ip6hdr, 0, sizeof(*ip6hdr)); 223 ip6hdr->ip6_flow = htonl(6<<28); /* Version. */ 224 ip6hdr->ip6_nxt = IPPROTO_FRAGMENT; 225 ip6hdr->ip6_hops = 255; 226 ip6hdr->ip6_src = addr6; 227 ip6hdr->ip6_dst = addr6; 228 fraghdr->ip6f_nxt = IPPROTO_UDP; 229 fraghdr->ip6f_reserved = 0; 230 fraghdr->ip6f_ident = htonl(ip_id++); 231 } else { 232 memset(iphdr, 0, sizeof(*iphdr)); 233 iphdr->ip_hl = 5; 234 iphdr->ip_v = 4; 235 iphdr->ip_tos = 0; 236 iphdr->ip_id = htons(ip_id++); 237 iphdr->ip_ttl = 0x40; 238 iphdr->ip_p = IPPROTO_UDP; 239 iphdr->ip_src.s_addr = htonl(INADDR_LOOPBACK); 240 iphdr->ip_dst = addr4; 241 iphdr->ip_sum = 0; 242 } 243 244 /* Occasionally test in-order fragments. */ 245 if (!cfg_overlap && (rand() % 100 < 15)) { 246 offset = 0; 247 while (offset < (UDP_HLEN + payload_len)) { 248 send_fragment(fd_raw, addr, alen, offset, ipv6); 249 offset += max_frag_len; 250 } 251 return; 252 } 253 254 /* Occasionally test IPv4 "runs" (see net/ipv4/ip_fragment.c) */ 255 if (!cfg_overlap && (rand() % 100 < 20) && 256 (payload_len > 9 * max_frag_len)) { 257 offset = 6 * max_frag_len; 258 while (offset < (UDP_HLEN + payload_len)) { 259 send_fragment(fd_raw, addr, alen, offset, ipv6); 260 offset += max_frag_len; 261 } 262 offset = 3 * max_frag_len; 263 while (offset < 6 * max_frag_len) { 264 send_fragment(fd_raw, addr, alen, offset, ipv6); 265 offset += max_frag_len; 266 } 267 offset = 0; 268 while (offset < 3 * max_frag_len) { 269 send_fragment(fd_raw, addr, alen, offset, ipv6); 270 offset += max_frag_len; 271 } 272 return; 273 } 274 275 /* Odd fragments. */ 276 offset = max_frag_len; 277 while (offset < (UDP_HLEN + payload_len)) { 278 send_fragment(fd_raw, addr, alen, offset, ipv6); 279 /* IPv4 ignores duplicates, so randomly send a duplicate. */ 280 if (rand() % 100 == 1) 281 send_fragment(fd_raw, addr, alen, offset, ipv6); 282 offset += 2 * max_frag_len; 283 } 284 285 if (cfg_overlap) { 286 /* Send an extra random fragment. 287 * 288 * Duplicates and some fragments completely inside 289 * previously sent fragments are dropped/ignored. So 290 * random offset and frag_len can result in a dropped 291 * fragment instead of a dropped queue/packet. Thus we 292 * hard-code offset and frag_len. 293 */ 294 if (max_frag_len * 4 < payload_len || max_frag_len < 16) { 295 /* not enough payload for random offset and frag_len. */ 296 offset = 8; 297 frag_len = UDP_HLEN + max_frag_len; 298 } else { 299 offset = rand() % (payload_len / 2); 300 frag_len = 2 * max_frag_len + 1 + rand() % 256; 301 } 302 if (ipv6) { 303 struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN); 304 /* sendto() returns EINVAL if offset + frag_len is too small. */ 305 /* In IPv6 if !!(frag_len % 8), the fragment is dropped. */ 306 frag_len &= ~0x7; 307 fraghdr->ip6f_offlg = htons(offset / 8 | IP6_MF); 308 ip6hdr->ip6_plen = htons(frag_len); 309 frag_len += IP6_HLEN; 310 } else { 311 frag_len += IP4_HLEN; 312 iphdr->ip_off = htons(offset / 8 | IP4_MF); 313 iphdr->ip_len = htons(frag_len); 314 } 315 res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen); 316 if (res < 0) 317 error(1, errno, "sendto overlap: %d", frag_len); 318 if (res != frag_len) 319 error(1, 0, "sendto overlap: %d vs %d", (int)res, frag_len); 320 frag_counter++; 321 } 322 323 /* Event fragments. */ 324 offset = 0; 325 while (offset < (UDP_HLEN + payload_len)) { 326 send_fragment(fd_raw, addr, alen, offset, ipv6); 327 /* IPv4 ignores duplicates, so randomly send a duplicate. */ 328 if (rand() % 100 == 1) 329 send_fragment(fd_raw, addr, alen, offset, ipv6); 330 offset += 2 * max_frag_len; 331 } 332 } 333 334 static void run_test(struct sockaddr *addr, socklen_t alen, bool ipv6) 335 { 336 int fd_tx_raw, fd_rx_udp; 337 /* Frag queue timeout is set to one second in the calling script; 338 * socket timeout should be just a bit longer to avoid tests interfering 339 * with each other. 340 */ 341 struct timeval tv = { .tv_sec = 1, .tv_usec = 10 }; 342 int idx; 343 int min_frag_len = 8; 344 345 /* Initialize the payload. */ 346 for (idx = 0; idx < MSG_LEN_MAX; ++idx) 347 udp_payload[idx] = idx % 256; 348 349 /* Open sockets. */ 350 fd_tx_raw = socket(addr->sa_family, SOCK_RAW, IPPROTO_RAW); 351 if (fd_tx_raw == -1) 352 error(1, errno, "socket tx_raw"); 353 354 fd_rx_udp = socket(addr->sa_family, SOCK_DGRAM, 0); 355 if (fd_rx_udp == -1) 356 error(1, errno, "socket rx_udp"); 357 if (bind(fd_rx_udp, addr, alen)) 358 error(1, errno, "bind"); 359 /* Fail fast. */ 360 if (setsockopt(fd_rx_udp, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv))) 361 error(1, errno, "setsockopt rcv timeout"); 362 363 for (payload_len = min_frag_len; payload_len < MSG_LEN_MAX; 364 payload_len += (rand() % 4096)) { 365 if (cfg_verbose) 366 printf("payload_len: %d\n", payload_len); 367 368 if (cfg_overlap) { 369 /* With overlaps, one send/receive pair below takes 370 * at least one second (== timeout) to run, so there 371 * is not enough test time to run a nested loop: 372 * the full overlap test takes 20-30 seconds. 373 */ 374 max_frag_len = min_frag_len + 375 rand() % (1500 - FRAG_HLEN - min_frag_len); 376 send_udp_frags(fd_tx_raw, addr, alen, ipv6); 377 recv_validate_udp(fd_rx_udp); 378 } else { 379 /* Without overlaps, each packet reassembly (== one 380 * send/receive pair below) takes very little time to 381 * run, so we can easily afford more thourough testing 382 * with a nested loop: the full non-overlap test takes 383 * less than one second). 384 */ 385 max_frag_len = min_frag_len; 386 do { 387 send_udp_frags(fd_tx_raw, addr, alen, ipv6); 388 recv_validate_udp(fd_rx_udp); 389 max_frag_len += 8 * (rand() % 8); 390 } while (max_frag_len < (1500 - FRAG_HLEN) && 391 max_frag_len <= payload_len); 392 } 393 } 394 395 /* Cleanup. */ 396 if (close(fd_tx_raw)) 397 error(1, errno, "close tx_raw"); 398 if (close(fd_rx_udp)) 399 error(1, errno, "close rx_udp"); 400 401 if (cfg_verbose) 402 printf("processed %d messages, %d fragments\n", 403 msg_counter, frag_counter); 404 405 fprintf(stderr, "PASS\n"); 406 } 407 408 409 static void run_test_v4(void) 410 { 411 struct sockaddr_in addr = {0}; 412 413 addr.sin_family = AF_INET; 414 addr.sin_port = htons(cfg_port); 415 addr.sin_addr = addr4; 416 417 run_test((void *)&addr, sizeof(addr), false /* !ipv6 */); 418 } 419 420 static void run_test_v6(void) 421 { 422 struct sockaddr_in6 addr = {0}; 423 424 addr.sin6_family = AF_INET6; 425 addr.sin6_port = htons(cfg_port); 426 addr.sin6_addr = addr6; 427 428 run_test((void *)&addr, sizeof(addr), true /* ipv6 */); 429 } 430 431 static void parse_opts(int argc, char **argv) 432 { 433 int c; 434 435 while ((c = getopt(argc, argv, "46opv")) != -1) { 436 switch (c) { 437 case '4': 438 cfg_do_ipv4 = true; 439 break; 440 case '6': 441 cfg_do_ipv6 = true; 442 break; 443 case 'o': 444 cfg_overlap = true; 445 break; 446 case 'p': 447 cfg_permissive = true; 448 break; 449 case 'v': 450 cfg_verbose = true; 451 break; 452 default: 453 error(1, 0, "%s: parse error", argv[0]); 454 } 455 } 456 } 457 458 int main(int argc, char **argv) 459 { 460 parse_opts(argc, argv); 461 seed = time(NULL); 462 srand(seed); 463 /* Print the seed to track/reproduce potential failures. */ 464 printf("seed = %d\n", seed); 465 466 if (cfg_do_ipv4) 467 run_test_v4(); 468 if (cfg_do_ipv6) 469 run_test_v6(); 470 471 return 0; 472 } 473