| 1 | /* UDP send/receive module for secnet */ |
| 2 | |
| 3 | /* |
| 4 | * This file is part of secnet. |
| 5 | * See README for full list of copyright holders. |
| 6 | * |
| 7 | * secnet is free software; you can redistribute it and/or modify it |
| 8 | * under the terms of the GNU General Public License as published by |
| 9 | * the Free Software Foundation; either version d of the License, or |
| 10 | * (at your option) any later version. |
| 11 | * |
| 12 | * secnet is distributed in the hope that it will be useful, but |
| 13 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License |
| 18 | * version 3 along with secnet; if not, see |
| 19 | * https://www.gnu.org/licenses/gpl.html. |
| 20 | */ |
| 21 | |
| 22 | /* This module enables sites to communicate by sending UDP |
| 23 | * packets. When an instance of the module is created we can |
| 24 | * optionally bind to a particular local IP address (not implemented |
| 25 | * yet). |
| 26 | * |
| 27 | * Packets are offered to registered receivers in turn. Once one |
| 28 | * accepts it, it isn't offered to any more. */ |
| 29 | |
| 30 | #include "secnet.h" |
| 31 | #include <stdio.h> |
| 32 | #include <unistd.h> |
| 33 | #include <fcntl.h> |
| 34 | #include <string.h> |
| 35 | #include <errno.h> |
| 36 | #include <sys/socket.h> |
| 37 | #include <sys/wait.h> |
| 38 | #include <netinet/in.h> |
| 39 | #include <arpa/inet.h> |
| 40 | #include "util.h" |
| 41 | #include "magic.h" |
| 42 | #include "unaligned.h" |
| 43 | #include "ipaddr.h" |
| 44 | #include "magic.h" |
| 45 | #include "comm-common.h" |
| 46 | |
| 47 | static comm_sendmsg_fn udp_sendmsg; |
| 48 | |
| 49 | struct udp { |
| 50 | struct udpcommon uc; |
| 51 | struct udpsocks socks; |
| 52 | bool_t addr_configured; |
| 53 | unsigned counter; |
| 54 | }; |
| 55 | |
| 56 | /* |
| 57 | * Re comm_addr.ix: This field allows us to note in the comm_addr |
| 58 | * which socket an incoming packet was received on. This is required |
| 59 | * for conveniently logging the actual source of a packet. But the ix |
| 60 | * does not formally form part of the address: it is not used when |
| 61 | * sending, nor when comparing two comm_addrs. |
| 62 | * |
| 63 | * The special value -1 means that the comm_addr was constructed by |
| 64 | * another module in secnet (eg the resolver), rather than being a |
| 65 | * description of the source of an incoming packet. |
| 66 | */ |
| 67 | |
| 68 | static const char *udp_addr_to_string(void *commst, const struct comm_addr *ca) |
| 69 | { |
| 70 | struct udp *st=commst; |
| 71 | struct udpsocks *socks=&st->socks; |
| 72 | static char sbuf[100]; |
| 73 | int ix=ca->ix>=0 ? ca->ix : 0; |
| 74 | |
| 75 | assert(ix>=0 && ix<socks->n_socks); |
| 76 | snprintf(sbuf, sizeof(sbuf), "udp#%u@l%d:%s%s-%s", |
| 77 | st->counter, st->uc.cc.loc.line, |
| 78 | iaddr_to_string(&socks->socks[ix].addr), |
| 79 | ca->ix<0 && socks->n_socks>1 ? "&" : "", |
| 80 | iaddr_to_string(&ca->ia)); |
| 81 | return sbuf; |
| 82 | } |
| 83 | |
| 84 | static int udp_socks_beforepoll(void *state, struct pollfd *fds, int *nfds_io, |
| 85 | int *timeout_io) |
| 86 | { |
| 87 | struct udpsocks *socks=state; |
| 88 | int i; |
| 89 | BEFOREPOLL_WANT_FDS(socks->n_socks); |
| 90 | for (i=0; i<socks->n_socks; i++) { |
| 91 | fds[i].fd=socks->socks[i].fd; |
| 92 | fds[i].events=POLLIN; |
| 93 | } |
| 94 | return 0; |
| 95 | } |
| 96 | |
| 97 | const char *af_name(int af) |
| 98 | { |
| 99 | switch (af) { |
| 100 | case AF_INET6: return "IPv6"; |
| 101 | case AF_INET: return "IPv4"; |
| 102 | case 0: return "(any)"; |
| 103 | default: abort(); |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | void udp_sock_experienced(struct log_if *lg, struct udpcommon *uc, |
| 108 | struct udpsocks *socks, struct udpsock *us, |
| 109 | const union iaddr *dest, int af, |
| 110 | int r, int errnoval) |
| 111 | { |
| 112 | bool_t success=r>=0; |
| 113 | if (us->experienced[!!dest][af][success]++) |
| 114 | return; |
| 115 | lg_perror(lg, uc->cc.cl.description, &uc->cc.loc, |
| 116 | success ? M_INFO : M_WARNING, |
| 117 | success ? 0 : errnoval, |
| 118 | "%s %s experiencing some %s %s%s%s%s%s%s", |
| 119 | socks->desc,iaddr_to_string(&us->addr), |
| 120 | success?"success":"trouble", |
| 121 | dest?"transmitting":"receiving", |
| 122 | af?" ":"", af?af_name(af):"", |
| 123 | dest?" (to ":"", |
| 124 | dest?iaddr_to_string(dest):"", |
| 125 | dest?")":""); |
| 126 | } |
| 127 | |
| 128 | static void udp_socks_afterpoll(void *state, struct pollfd *fds, int nfds) |
| 129 | { |
| 130 | struct udpsocks *socks=state; |
| 131 | struct udpcommon *uc=socks->uc; |
| 132 | union iaddr from; |
| 133 | socklen_t fromlen; |
| 134 | bool_t done; |
| 135 | int rv; |
| 136 | int i; |
| 137 | |
| 138 | struct commcommon *cc=&uc->cc; |
| 139 | |
| 140 | for (i=0; i<socks->n_socks; i++) { |
| 141 | struct udpsock *us=&socks->socks[i]; |
| 142 | if (i>=nfds) continue; |
| 143 | if (!(fds[i].revents & POLLIN)) continue; |
| 144 | assert(fds[i].fd == us->fd); |
| 145 | int fd=us->fd; |
| 146 | do { |
| 147 | fromlen=sizeof(from); |
| 148 | BUF_ASSERT_FREE(cc->rbuf); |
| 149 | BUF_ALLOC(cc->rbuf,"udp_afterpoll"); |
| 150 | buffer_init(cc->rbuf,calculate_max_start_pad()); |
| 151 | rv=recvfrom(fd, cc->rbuf->start, |
| 152 | buf_remaining_space(cc->rbuf), |
| 153 | 0, &from.sa, &fromlen); |
| 154 | if (rv>0) { |
| 155 | cc->rbuf->size=rv; |
| 156 | if (uc->use_proxy) { |
| 157 | /* Check that the packet came from our poxy server; |
| 158 | we shouldn't be contacted directly by anybody else |
| 159 | (since they can trivially forge source addresses) */ |
| 160 | if (!iaddr_equal(&from,&uc->proxy,False)) { |
| 161 | Message(M_INFO,"udp: received packet that's not " |
| 162 | "from the proxy\n"); |
| 163 | BUF_FREE(cc->rbuf); |
| 164 | continue; |
| 165 | } |
| 166 | /* proxy protocol supports ipv4 transport only */ |
| 167 | from.sa.sa_family=AF_INET; |
| 168 | BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_addr,4); |
| 169 | buf_unprepend(cc->rbuf,2); |
| 170 | BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_port,2); |
| 171 | } |
| 172 | struct comm_addr ca; |
| 173 | ca.comm=&cc->ops; |
| 174 | ca.ia=from; |
| 175 | ca.ix=i; |
| 176 | done=comm_notify(&cc->notify, cc->rbuf, &ca); |
| 177 | if (done) { |
| 178 | udp_sock_experienced(0,uc,socks,us,0, |
| 179 | from.sa.sa_family,0,0); |
| 180 | } else { |
| 181 | uint32_t msgtype; |
| 182 | if (cc->rbuf->size>12 /* prevents traffic amplification */ |
| 183 | && ((msgtype=get_uint32(cc->rbuf->start+8)) |
| 184 | != LABEL_NAK)) { |
| 185 | uint32_t source,dest; |
| 186 | /* Manufacture and send NAK packet */ |
| 187 | source=get_uint32(cc->rbuf->start); /* Us */ |
| 188 | dest=get_uint32(cc->rbuf->start+4); /* Them */ |
| 189 | send_nak(&ca,source,dest,msgtype,cc->rbuf,"unwanted"); |
| 190 | } |
| 191 | BUF_FREE(cc->rbuf); |
| 192 | } |
| 193 | BUF_ASSERT_FREE(cc->rbuf); |
| 194 | } else { /* rv<=0 */ |
| 195 | if (errno!=EINTR && !iswouldblock(errno)) |
| 196 | udp_sock_experienced(0,uc,socks,us, 0,0, rv,errno); |
| 197 | BUF_FREE(cc->rbuf); |
| 198 | } |
| 199 | } while (rv>=0); |
| 200 | } |
| 201 | } |
| 202 | |
| 203 | static bool_t udp_sendmsg(void *commst, struct buffer_if *buf, |
| 204 | const struct comm_addr *dest) |
| 205 | { |
| 206 | struct udp *st=commst; |
| 207 | struct udpcommon *uc=&st->uc; |
| 208 | struct udpsocks *socks=&st->socks; |
| 209 | uint8_t *sa; |
| 210 | |
| 211 | if (uc->use_proxy) { |
| 212 | struct udpsock *us=&socks->socks[0]; |
| 213 | sa=buf_prepend(buf,8); |
| 214 | if (dest->ia.sa.sa_family != AF_INET) { |
| 215 | Message(M_INFO, |
| 216 | "udp: proxy means dropping outgoing non-IPv4 packet to %s\n", |
| 217 | iaddr_to_string(&dest->ia)); |
| 218 | return False; |
| 219 | } |
| 220 | memcpy(sa,&dest->ia.sin.sin_addr,4); |
| 221 | memset(sa+4,0,4); |
| 222 | memcpy(sa+6,&dest->ia.sin.sin_port,2); |
| 223 | int r=sendto(us->fd,sa,buf->size+8,0,&uc->proxy.sa, |
| 224 | iaddr_socklen(&uc->proxy)); |
| 225 | udp_sock_experienced(0,uc,socks,us, &dest->ia,0, r,errno); |
| 226 | buf_unprepend(buf,8); |
| 227 | } else { |
| 228 | int i,r; |
| 229 | bool_t allunsupported=True; |
| 230 | int af=dest->ia.sa.sa_family; |
| 231 | for (i=0; i<socks->n_socks; i++) { |
| 232 | struct udpsock *us=&socks->socks[i]; |
| 233 | if (us->addr.sa.sa_family != af) |
| 234 | /* no point even trying */ |
| 235 | continue; |
| 236 | r=sendto(us->fd, buf->start, buf->size, 0, |
| 237 | &dest->ia.sa, iaddr_socklen(&dest->ia)); |
| 238 | udp_sock_experienced(0,uc,socks,us, &dest->ia,af, r,errno); |
| 239 | if (r>=0) return True; |
| 240 | if (!(errno==EAFNOSUPPORT || errno==ENETUNREACH)) |
| 241 | /* who knows what that error means? */ |
| 242 | allunsupported=False; |
| 243 | } |
| 244 | return !allunsupported; /* see doc for comm_sendmsg_fn in secnet.h */ |
| 245 | } |
| 246 | |
| 247 | return True; |
| 248 | } |
| 249 | |
| 250 | void udp_destroy_socket(struct udpcommon *uc, struct udpsock *us) |
| 251 | { |
| 252 | if (us->fd>=0) { |
| 253 | close(us->fd); |
| 254 | us->fd=-1; |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | #define FAIL_LG 0, cc->cl.description, &cc->loc, failmsgclass |
| 259 | #define FAIL(...) do{ \ |
| 260 | lg_perror(FAIL_LG,errno,__VA_ARGS__); \ |
| 261 | goto failed; \ |
| 262 | }while(0) |
| 263 | |
| 264 | static bool_t record_socket_gotaddr(struct udpcommon *uc, struct udpsock *us, |
| 265 | int failmsgclass) |
| 266 | { |
| 267 | struct commcommon *cc=&uc->cc; |
| 268 | socklen_t salen=sizeof(us->addr); |
| 269 | int r=getsockname(us->fd,&us->addr.sa,&salen); |
| 270 | if (r) FAIL("getsockname()"); |
| 271 | if (salen>sizeof(us->addr)) { errno=0; FAIL("getsockname() length"); } |
| 272 | return True; |
| 273 | |
| 274 | failed: |
| 275 | return False; |
| 276 | } |
| 277 | |
| 278 | bool_t udp_import_socket(struct udpcommon *uc, struct udpsock *us, |
| 279 | int failmsgclass, int fd) |
| 280 | { |
| 281 | FILLZERO(us->experienced); |
| 282 | us->fd=fd; |
| 283 | return record_socket_gotaddr(uc,us,failmsgclass); |
| 284 | } |
| 285 | |
| 286 | bool_t udp_make_socket(struct udpcommon *uc, struct udpsock *us, |
| 287 | int failmsgclass) |
| 288 | { |
| 289 | const union iaddr *addr=&us->addr; |
| 290 | struct commcommon *cc=&uc->cc; |
| 291 | us->fd=-1; |
| 292 | |
| 293 | FILLZERO(us->experienced); |
| 294 | us->fd=socket(addr->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP); |
| 295 | if (us->fd<0) FAIL("socket"); |
| 296 | setnonblock(us->fd); |
| 297 | setcloexec(us->fd); |
| 298 | #ifdef CONFIG_IPV6 |
| 299 | if (addr->sa.sa_family==AF_INET6) { |
| 300 | int r; |
| 301 | int optval=1; |
| 302 | socklen_t optlen=sizeof(optval); |
| 303 | r=setsockopt(us->fd,IPPROTO_IPV6,IPV6_V6ONLY,&optval,optlen); |
| 304 | if (r) FAIL("setsockopt(,IPV6_V6ONLY,&1,)"); |
| 305 | } |
| 306 | #endif |
| 307 | |
| 308 | if (uc->authbind) { |
| 309 | pid_t c; |
| 310 | int status; |
| 311 | char desc[200]; |
| 312 | snprintf(desc,sizeof(desc),"authbind for %s: %s", |
| 313 | iaddr_to_string(addr), uc->authbind); |
| 314 | |
| 315 | /* XXX this fork() and waitpid() business needs to be hidden |
| 316 | in some system-specific library functions. */ |
| 317 | c=fork(); |
| 318 | if (c==-1) |
| 319 | FAIL("fork() for authbind"); |
| 320 | if (c==0) { |
| 321 | char *argv[5], addrstr[33], portstr[5]; |
| 322 | const char *addrfam; |
| 323 | int port; |
| 324 | afterfork(); |
| 325 | switch (addr->sa.sa_family) { |
| 326 | case AF_INET: |
| 327 | sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr); |
| 328 | port=addr->sin.sin_port; |
| 329 | addrfam=NULL; |
| 330 | break; |
| 331 | #ifdef CONFIG_IPV6 |
| 332 | case AF_INET6: { |
| 333 | int i; |
| 334 | for (i=0; i<16; i++) |
| 335 | sprintf(addrstr+i*2,"%02X",addr->sin6.sin6_addr.s6_addr[i]); |
| 336 | port=addr->sin6.sin6_port; |
| 337 | addrfam="6"; |
| 338 | break; |
| 339 | } |
| 340 | #endif /*CONFIG_IPV6*/ |
| 341 | default: |
| 342 | fatal("udp (%s:%d): unsupported address family for authbind", |
| 343 | cc->loc.file,cc->loc.line); |
| 344 | } |
| 345 | sprintf(portstr,"%04X",port); |
| 346 | argv[0]=uc->authbind; |
| 347 | argv[1]=addrstr; |
| 348 | argv[2]=portstr; |
| 349 | argv[3]=(char*)addrfam; |
| 350 | argv[4]=NULL; |
| 351 | dup2(us->fd,0); |
| 352 | execvp(uc->authbind,argv); |
| 353 | _exit(255); |
| 354 | } |
| 355 | while (waitpid(c,&status,0)==-1) { |
| 356 | if (errno==EINTR) continue; |
| 357 | FAIL("waitpid for authbind"); |
| 358 | } |
| 359 | if (status) { |
| 360 | if (WIFEXITED(status) && WEXITSTATUS(status)<127) { |
| 361 | int es=WEXITSTATUS(status); |
| 362 | lg_perror(FAIL_LG,es, |
| 363 | "%s exited with error exit status %d;" |
| 364 | " indicates error",desc,es); |
| 365 | } else { |
| 366 | lg_exitstatus(FAIL_LG,status,desc); |
| 367 | } |
| 368 | goto failed; |
| 369 | } |
| 370 | } else { |
| 371 | if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0) |
| 372 | FAIL("bind (%s)",iaddr_to_string(addr)); |
| 373 | } |
| 374 | |
| 375 | bool_t ok=record_socket_gotaddr(uc,us,failmsgclass); |
| 376 | if (!ok) goto failed; |
| 377 | |
| 378 | return True; |
| 379 | |
| 380 | failed: |
| 381 | udp_destroy_socket(uc,us); |
| 382 | return False; |
| 383 | } |
| 384 | |
| 385 | #undef FAIL |
| 386 | |
| 387 | void udp_socks_register(struct udpcommon *uc, struct udpsocks *socks, |
| 388 | const char *desc) |
| 389 | { |
| 390 | socks->uc=uc; |
| 391 | socks->desc=desc; |
| 392 | socks->interest= |
| 393 | register_for_poll(socks,udp_socks_beforepoll,udp_socks_afterpoll,"udp"); |
| 394 | } |
| 395 | |
| 396 | void udp_socks_deregister(struct udpcommon *uc, struct udpsocks *socks) |
| 397 | { |
| 398 | socks->uc=uc; |
| 399 | deregister_for_poll(socks->interest); |
| 400 | } |
| 401 | |
| 402 | void udp_socks_childpersist(struct udpcommon *uc, struct udpsocks *socks) |
| 403 | { |
| 404 | int i; |
| 405 | for (i=0; i<socks->n_socks; i++) |
| 406 | udp_destroy_socket(uc,&socks->socks[i]); |
| 407 | } |
| 408 | |
| 409 | static void udp_childpersist_hook(void *sst, uint32_t new_phase) |
| 410 | { |
| 411 | struct udp *st=sst; |
| 412 | udp_socks_childpersist(&st->uc,&st->socks); |
| 413 | } |
| 414 | |
| 415 | static void udp_phase_hook(void *sst, uint32_t new_phase) |
| 416 | { |
| 417 | struct udp *st=sst; |
| 418 | struct udpsocks *socks=&st->socks; |
| 419 | struct udpcommon *uc=&st->uc; |
| 420 | int i; |
| 421 | bool_t anydone=0; |
| 422 | |
| 423 | for (i=0; i<socks->n_socks; i++) { |
| 424 | bool_t required=st->addr_configured |
| 425 | || (!anydone && i==socks->n_socks-1); |
| 426 | anydone += udp_make_socket(uc,&socks->socks[i], |
| 427 | required ? M_FATAL : M_WARNING); |
| 428 | } |
| 429 | |
| 430 | udp_socks_register(uc,socks, uc->use_proxy ? "proxy" : "socket"); |
| 431 | |
| 432 | add_hook(PHASE_CHILDPERSIST,udp_childpersist_hook,st); |
| 433 | } |
| 434 | |
| 435 | static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context, |
| 436 | list_t *args) |
| 437 | { |
| 438 | static unsigned counter; |
| 439 | |
| 440 | struct udp *st; |
| 441 | list_t *caddrl; |
| 442 | list_t *l; |
| 443 | uint32_t a; |
| 444 | int i; |
| 445 | |
| 446 | COMM_APPLY(st,&st->uc.cc,udp_,"udp",loc); |
| 447 | COMM_APPLY_STANDARD(st,&st->uc.cc,"udp",args); |
| 448 | UDP_APPLY_STANDARD(st,&st->uc,"udp"); |
| 449 | |
| 450 | struct udpcommon *uc=&st->uc; |
| 451 | struct udpsocks *socks=&st->socks; |
| 452 | struct commcommon *cc=&uc->cc; |
| 453 | |
| 454 | st->counter=counter++; |
| 455 | |
| 456 | union iaddr defaultaddrs[] = { |
| 457 | #ifdef CONFIG_IPV6 |
| 458 | { .sin6 = { .sin6_family=AF_INET6, |
| 459 | .sin6_port=htons(uc->port), |
| 460 | .sin6_addr=IN6ADDR_ANY_INIT } }, |
| 461 | #endif |
| 462 | { .sin = { .sin_family=AF_INET, |
| 463 | .sin_port=htons(uc->port), |
| 464 | .sin_addr= { .s_addr=INADDR_ANY } } } |
| 465 | }; |
| 466 | |
| 467 | caddrl=dict_lookup(d,"address"); |
| 468 | st->addr_configured=!!caddrl; |
| 469 | socks->n_socks=st->addr_configured ? list_length(caddrl) |
| 470 | : (int)ARRAY_SIZE(defaultaddrs); |
| 471 | if (socks->n_socks<=0 || socks->n_socks>UDP_MAX_SOCKETS) |
| 472 | cfgfatal(cc->loc,"udp","`address' must be 1..%d addresses", |
| 473 | UDP_MAX_SOCKETS); |
| 474 | |
| 475 | for (i=0; i<socks->n_socks; i++) { |
| 476 | struct udpsock *us=&socks->socks[i]; |
| 477 | if (!st->addr_configured) { |
| 478 | us->addr=defaultaddrs[i]; |
| 479 | } else { |
| 480 | string_item_to_iaddr(list_elem(caddrl,i),uc->port,&us->addr,"udp"); |
| 481 | } |
| 482 | us->fd=-1; |
| 483 | } |
| 484 | |
| 485 | l=dict_lookup(d,"proxy"); |
| 486 | if (l) { |
| 487 | uc->use_proxy=True; |
| 488 | uc->proxy.sa.sa_family=AF_INET; |
| 489 | item=list_elem(l,0); |
| 490 | if (!item || item->type!=t_string) { |
| 491 | cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n"); |
| 492 | } |
| 493 | a=string_item_to_ipaddr(item,"proxy"); |
| 494 | uc->proxy.sin.sin_addr.s_addr=htonl(a); |
| 495 | item=list_elem(l,1); |
| 496 | if (!item || item->type!=t_number) { |
| 497 | cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n"); |
| 498 | } |
| 499 | uc->proxy.sin.sin_port=htons(item->data.number); |
| 500 | } |
| 501 | |
| 502 | update_max_start_pad(&comm_max_start_pad, uc->use_proxy ? 8 : 0); |
| 503 | |
| 504 | add_hook(PHASE_GETRESOURCES,udp_phase_hook,st); |
| 505 | |
| 506 | return new_closure(&cc->cl); |
| 507 | } |
| 508 | |
| 509 | void udp_module(dict_t *dict) |
| 510 | { |
| 511 | add_closure(dict,"udp",udp_apply); |
| 512 | } |