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 unsigned short cfg_port = 9000; 24 25 const struct in_addr addr4 = { .s_addr = __constant_htonl(INADDR_LOOPBACK + 2) }; 26 const struct in6_addr addr6 = IN6ADDR_LOOPBACK_INIT; 27 28 #define IP4_HLEN (sizeof(struct iphdr)) 29 #define IP6_HLEN (sizeof(struct ip6_hdr)) 30 #define UDP_HLEN (sizeof(struct udphdr)) 31 32 /* IPv6 fragment header lenth. */ 33 #define FRAG_HLEN 8 34 35 static int payload_len; 36 static int max_frag_len; 37 38 #define MSG_LEN_MAX 60000 /* Max UDP payload length. */ 39 40 #define IP4_MF (1u << 13) /* IPv4 MF flag. */ 41 #define IP6_MF (1) /* IPv6 MF flag. */ 42 43 #define CSUM_MANGLED_0 (0xffff) 44 45 static uint8_t udp_payload[MSG_LEN_MAX]; 46 static uint8_t ip_frame[IP_MAXPACKET]; 47 static uint32_t ip_id = 0xabcd; 48 static int msg_counter; 49 static int frag_counter; 50 static unsigned int seed; 51 52 /* Receive a UDP packet. Validate it matches udp_payload. */ 53 static void recv_validate_udp(int fd_udp) 54 { 55 ssize_t ret; 56 static uint8_t recv_buff[MSG_LEN_MAX]; 57 58 ret = recv(fd_udp, recv_buff, payload_len, 0); 59 msg_counter++; 60 61 if (cfg_overlap) { 62 if (ret != -1) 63 error(1, 0, "recv: expected timeout; got %d", 64 (int)ret); 65 if (errno != ETIMEDOUT && errno != EAGAIN) 66 error(1, errno, "recv: expected timeout: %d", 67 errno); 68 return; /* OK */ 69 } 70 71 if (ret == -1) 72 error(1, errno, "recv: payload_len = %d max_frag_len = %d", 73 payload_len, max_frag_len); 74 if (ret != payload_len) 75 error(1, 0, "recv: wrong size: %d vs %d", (int)ret, payload_len); 76 if (memcmp(udp_payload, recv_buff, payload_len)) 77 error(1, 0, "recv: wrong data"); 78 } 79 80 static uint32_t raw_checksum(uint8_t *buf, int len, uint32_t sum) 81 { 82 int i; 83 84 for (i = 0; i < (len & ~1U); i += 2) { 85 sum += (u_int16_t)ntohs(*((u_int16_t *)(buf + i))); 86 if (sum > 0xffff) 87 sum -= 0xffff; 88 } 89 90 if (i < len) { 91 sum += buf[i] << 8; 92 if (sum > 0xffff) 93 sum -= 0xffff; 94 } 95 96 return sum; 97 } 98 99 static uint16_t udp_checksum(struct ip *iphdr, struct udphdr *udphdr) 100 { 101 uint32_t sum = 0; 102 uint16_t res; 103 104 sum = raw_checksum((uint8_t *)&iphdr->ip_src, 2 * sizeof(iphdr->ip_src), 105 IPPROTO_UDP + (uint32_t)(UDP_HLEN + payload_len)); 106 sum = raw_checksum((uint8_t *)udphdr, UDP_HLEN, sum); 107 sum = raw_checksum((uint8_t *)udp_payload, payload_len, sum); 108 res = 0xffff & ~sum; 109 if (res) 110 return htons(res); 111 else 112 return CSUM_MANGLED_0; 113 } 114 115 static uint16_t udp6_checksum(struct ip6_hdr *iphdr, struct udphdr *udphdr) 116 { 117 uint32_t sum = 0; 118 uint16_t res; 119 120 sum = raw_checksum((uint8_t *)&iphdr->ip6_src, 2 * sizeof(iphdr->ip6_src), 121 IPPROTO_UDP); 122 sum = raw_checksum((uint8_t *)&udphdr->len, sizeof(udphdr->len), sum); 123 sum = raw_checksum((uint8_t *)udphdr, UDP_HLEN, sum); 124 sum = raw_checksum((uint8_t *)udp_payload, payload_len, sum); 125 res = 0xffff & ~sum; 126 if (res) 127 return htons(res); 128 else 129 return CSUM_MANGLED_0; 130 } 131 132 static void send_fragment(int fd_raw, struct sockaddr *addr, socklen_t alen, 133 int offset, bool ipv6) 134 { 135 int frag_len; 136 int res; 137 int payload_offset = offset > 0 ? offset - UDP_HLEN : 0; 138 uint8_t *frag_start = ipv6 ? ip_frame + IP6_HLEN + FRAG_HLEN : 139 ip_frame + IP4_HLEN; 140 141 if (offset == 0) { 142 struct udphdr udphdr; 143 udphdr.source = htons(cfg_port + 1); 144 udphdr.dest = htons(cfg_port); 145 udphdr.len = htons(UDP_HLEN + payload_len); 146 udphdr.check = 0; 147 if (ipv6) 148 udphdr.check = udp6_checksum((struct ip6_hdr *)ip_frame, &udphdr); 149 else 150 udphdr.check = udp_checksum((struct ip *)ip_frame, &udphdr); 151 memcpy(frag_start, &udphdr, UDP_HLEN); 152 } 153 154 if (ipv6) { 155 struct ip6_hdr *ip6hdr = (struct ip6_hdr *)ip_frame; 156 struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN); 157 if (payload_len - payload_offset <= max_frag_len && offset > 0) { 158 /* This is the last fragment. */ 159 frag_len = FRAG_HLEN + payload_len - payload_offset; 160 fraghdr->ip6f_offlg = htons(offset); 161 } else { 162 frag_len = FRAG_HLEN + max_frag_len; 163 fraghdr->ip6f_offlg = htons(offset | IP6_MF); 164 } 165 ip6hdr->ip6_plen = htons(frag_len); 166 if (offset == 0) 167 memcpy(frag_start + UDP_HLEN, udp_payload, 168 frag_len - FRAG_HLEN - UDP_HLEN); 169 else 170 memcpy(frag_start, udp_payload + payload_offset, 171 frag_len - FRAG_HLEN); 172 frag_len += IP6_HLEN; 173 } else { 174 struct ip *iphdr = (struct ip *)ip_frame; 175 if (payload_len - payload_offset <= max_frag_len && offset > 0) { 176 /* This is the last fragment. */ 177 frag_len = IP4_HLEN + payload_len - payload_offset; 178 iphdr->ip_off = htons(offset / 8); 179 } else { 180 frag_len = IP4_HLEN + max_frag_len; 181 iphdr->ip_off = htons(offset / 8 | IP4_MF); 182 } 183 iphdr->ip_len = htons(frag_len); 184 if (offset == 0) 185 memcpy(frag_start + UDP_HLEN, udp_payload, 186 frag_len - IP4_HLEN - UDP_HLEN); 187 else 188 memcpy(frag_start, udp_payload + payload_offset, 189 frag_len - IP4_HLEN); 190 } 191 192 res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen); 193 if (res < 0) 194 error(1, errno, "send_fragment"); 195 if (res != frag_len) 196 error(1, 0, "send_fragment: %d vs %d", res, frag_len); 197 198 frag_counter++; 199 } 200 201 static void send_udp_frags(int fd_raw, struct sockaddr *addr, 202 socklen_t alen, bool ipv6) 203 { 204 struct ip *iphdr = (struct ip *)ip_frame; 205 struct ip6_hdr *ip6hdr = (struct ip6_hdr *)ip_frame; 206 int res; 207 int offset; 208 int frag_len; 209 210 /* Send the UDP datagram using raw IP fragments: the 0th fragment 211 * has the UDP header; other fragments are pieces of udp_payload 212 * split in chunks of frag_len size. 213 * 214 * Odd fragments (1st, 3rd, 5th, etc.) are sent out first, then 215 * even fragments (0th, 2nd, etc.) are sent out. 216 */ 217 if (ipv6) { 218 struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN); 219 ((struct sockaddr_in6 *)addr)->sin6_port = 0; 220 memset(ip6hdr, 0, sizeof(*ip6hdr)); 221 ip6hdr->ip6_flow = htonl(6<<28); /* Version. */ 222 ip6hdr->ip6_nxt = IPPROTO_FRAGMENT; 223 ip6hdr->ip6_hops = 255; 224 ip6hdr->ip6_src = addr6; 225 ip6hdr->ip6_dst = addr6; 226 fraghdr->ip6f_nxt = IPPROTO_UDP; 227 fraghdr->ip6f_reserved = 0; 228 fraghdr->ip6f_ident = htonl(ip_id++); 229 } else { 230 memset(iphdr, 0, sizeof(*iphdr)); 231 iphdr->ip_hl = 5; 232 iphdr->ip_v = 4; 233 iphdr->ip_tos = 0; 234 iphdr->ip_id = htons(ip_id++); 235 iphdr->ip_ttl = 0x40; 236 iphdr->ip_p = IPPROTO_UDP; 237 iphdr->ip_src.s_addr = htonl(INADDR_LOOPBACK); 238 iphdr->ip_dst = addr4; 239 iphdr->ip_sum = 0; 240 } 241 242 /* Odd fragments. */ 243 offset = max_frag_len; 244 while (offset < (UDP_HLEN + payload_len)) { 245 send_fragment(fd_raw, addr, alen, offset, ipv6); 246 offset += 2 * max_frag_len; 247 } 248 249 if (cfg_overlap) { 250 /* Send an extra random fragment. */ 251 offset = rand() % (UDP_HLEN + payload_len - 1); 252 /* sendto() returns EINVAL if offset + frag_len is too small. */ 253 if (ipv6) { 254 struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN); 255 frag_len = max_frag_len + rand() % 256; 256 /* In IPv6 if !!(frag_len % 8), the fragment is dropped. */ 257 frag_len &= ~0x7; 258 fraghdr->ip6f_offlg = htons(offset / 8 | IP6_MF); 259 ip6hdr->ip6_plen = htons(frag_len); 260 frag_len += IP6_HLEN; 261 } else { 262 frag_len = IP4_HLEN + UDP_HLEN + rand() % 256; 263 iphdr->ip_off = htons(offset / 8 | IP4_MF); 264 iphdr->ip_len = htons(frag_len); 265 } 266 res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen); 267 if (res < 0) 268 error(1, errno, "sendto overlap"); 269 if (res != frag_len) 270 error(1, 0, "sendto overlap: %d vs %d", (int)res, frag_len); 271 frag_counter++; 272 } 273 274 /* Event fragments. */ 275 offset = 0; 276 while (offset < (UDP_HLEN + payload_len)) { 277 send_fragment(fd_raw, addr, alen, offset, ipv6); 278 offset += 2 * max_frag_len; 279 } 280 } 281 282 static void run_test(struct sockaddr *addr, socklen_t alen, bool ipv6) 283 { 284 int fd_tx_raw, fd_rx_udp; 285 struct timeval tv = { .tv_sec = 0, .tv_usec = 10 * 1000 }; 286 int idx; 287 int min_frag_len = ipv6 ? 1280 : 8; 288 289 /* Initialize the payload. */ 290 for (idx = 0; idx < MSG_LEN_MAX; ++idx) 291 udp_payload[idx] = idx % 256; 292 293 /* Open sockets. */ 294 fd_tx_raw = socket(addr->sa_family, SOCK_RAW, IPPROTO_RAW); 295 if (fd_tx_raw == -1) 296 error(1, errno, "socket tx_raw"); 297 298 fd_rx_udp = socket(addr->sa_family, SOCK_DGRAM, 0); 299 if (fd_rx_udp == -1) 300 error(1, errno, "socket rx_udp"); 301 if (bind(fd_rx_udp, addr, alen)) 302 error(1, errno, "bind"); 303 /* Fail fast. */ 304 if (setsockopt(fd_rx_udp, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv))) 305 error(1, errno, "setsockopt rcv timeout"); 306 307 for (payload_len = min_frag_len; payload_len < MSG_LEN_MAX; 308 payload_len += (rand() % 4096)) { 309 if (cfg_verbose) 310 printf("payload_len: %d\n", payload_len); 311 max_frag_len = min_frag_len; 312 do { 313 send_udp_frags(fd_tx_raw, addr, alen, ipv6); 314 recv_validate_udp(fd_rx_udp); 315 max_frag_len += 8 * (rand() % 8); 316 } while (max_frag_len < (1500 - FRAG_HLEN) && max_frag_len <= payload_len); 317 } 318 319 /* Cleanup. */ 320 if (close(fd_tx_raw)) 321 error(1, errno, "close tx_raw"); 322 if (close(fd_rx_udp)) 323 error(1, errno, "close rx_udp"); 324 325 if (cfg_verbose) 326 printf("processed %d messages, %d fragments\n", 327 msg_counter, frag_counter); 328 329 fprintf(stderr, "PASS\n"); 330 } 331 332 333 static void run_test_v4(void) 334 { 335 struct sockaddr_in addr = {0}; 336 337 addr.sin_family = AF_INET; 338 addr.sin_port = htons(cfg_port); 339 addr.sin_addr = addr4; 340 341 run_test((void *)&addr, sizeof(addr), false /* !ipv6 */); 342 } 343 344 static void run_test_v6(void) 345 { 346 struct sockaddr_in6 addr = {0}; 347 348 addr.sin6_family = AF_INET6; 349 addr.sin6_port = htons(cfg_port); 350 addr.sin6_addr = addr6; 351 352 run_test((void *)&addr, sizeof(addr), true /* ipv6 */); 353 } 354 355 static void parse_opts(int argc, char **argv) 356 { 357 int c; 358 359 while ((c = getopt(argc, argv, "46ov")) != -1) { 360 switch (c) { 361 case '4': 362 cfg_do_ipv4 = true; 363 break; 364 case '6': 365 cfg_do_ipv6 = true; 366 break; 367 case 'o': 368 cfg_overlap = true; 369 break; 370 case 'v': 371 cfg_verbose = true; 372 break; 373 default: 374 error(1, 0, "%s: parse error", argv[0]); 375 } 376 } 377 } 378 379 int main(int argc, char **argv) 380 { 381 parse_opts(argc, argv); 382 seed = time(NULL); 383 srand(seed); 384 /* Print the seed to track/reproduce potential failures. */ 385 printf("seed = %d\n", seed); 386 387 if (cfg_do_ipv4) 388 run_test_v4(); 389 if (cfg_do_ipv6) 390 run_test_v6(); 391 392 return 0; 393 } 394