| 1 | /* UDP send/receive module for secnet */ |
| 2 | |
| 3 | /* This module enables sites to communicate by sending UDP |
| 4 | * packets. When an instance of the module is created we can |
| 5 | * optionally bind to a particular local IP address (not implemented |
| 6 | * yet). |
| 7 | * |
| 8 | * Packets are offered to registered receivers in turn. Once one |
| 9 | * accepts it, it isn't offered to any more. */ |
| 10 | |
| 11 | #include "secnet.h" |
| 12 | #include <stdio.h> |
| 13 | #include <unistd.h> |
| 14 | #include <fcntl.h> |
| 15 | #include <string.h> |
| 16 | #include <errno.h> |
| 17 | #include <sys/socket.h> |
| 18 | #include <sys/wait.h> |
| 19 | #include <netinet/in.h> |
| 20 | #include <arpa/inet.h> |
| 21 | #include "util.h" |
| 22 | #include "magic.h" |
| 23 | #include "unaligned.h" |
| 24 | #include "ipaddr.h" |
| 25 | #include "magic.h" |
| 26 | #include "comm-common.h" |
| 27 | |
| 28 | static comm_sendmsg_fn udp_sendmsg; |
| 29 | |
| 30 | struct udp { |
| 31 | struct udpcommon uc; |
| 32 | struct udpsocks socks; |
| 33 | }; |
| 34 | |
| 35 | /* |
| 36 | * Re comm_addr.ix: This field allows us to note in the comm_addr |
| 37 | * which socket an incoming packet was received on. This is required |
| 38 | * for conveniently logging the actual source of a packet. But the ix |
| 39 | * does not formally form part of the address: it is not used when |
| 40 | * sending, nor when comparing two comm_addrs. |
| 41 | * |
| 42 | * The special value -1 means that the comm_addr was constructed by |
| 43 | * another module in secnet (eg the resolver), rather than being a |
| 44 | * description of the source of an incoming packet. |
| 45 | */ |
| 46 | |
| 47 | static const char *udp_addr_to_string(void *commst, const struct comm_addr *ca) |
| 48 | { |
| 49 | struct udp *st=commst; |
| 50 | struct udpsocks *socks=&st->socks; |
| 51 | static char sbuf[100]; |
| 52 | int ix=ca->ix>=0 ? ca->ix : 0; |
| 53 | |
| 54 | assert(ix>=0 && ix<socks->n_socks); |
| 55 | snprintf(sbuf, sizeof(sbuf), "udp:%s%s-%s", |
| 56 | iaddr_to_string(&socks->socks[ix].addr), |
| 57 | ca->ix<0 ? "&" : "", |
| 58 | iaddr_to_string(&ca->ia)); |
| 59 | return sbuf; |
| 60 | } |
| 61 | |
| 62 | static int udp_socks_beforepoll(void *state, struct pollfd *fds, int *nfds_io, |
| 63 | int *timeout_io) |
| 64 | { |
| 65 | struct udpsocks *socks=state; |
| 66 | int i; |
| 67 | BEFOREPOLL_WANT_FDS(socks->n_socks); |
| 68 | for (i=0; i<socks->n_socks; i++) { |
| 69 | fds[i].fd=socks->socks[i].fd; |
| 70 | fds[i].events=POLLIN; |
| 71 | } |
| 72 | return 0; |
| 73 | } |
| 74 | |
| 75 | static void udp_socks_afterpoll(void *state, struct pollfd *fds, int nfds) |
| 76 | { |
| 77 | struct udpsocks *socks=state; |
| 78 | struct udpcommon *uc=socks->uc; |
| 79 | union iaddr from; |
| 80 | socklen_t fromlen; |
| 81 | bool_t done; |
| 82 | int rv; |
| 83 | int i; |
| 84 | |
| 85 | struct commcommon *cc=&uc->cc; |
| 86 | |
| 87 | for (i=0; i<socks->n_socks; i++) { |
| 88 | if (i>=nfds) continue; |
| 89 | if (!(fds[i].revents & POLLIN)) continue; |
| 90 | assert(fds[i].fd == socks->socks[i].fd); |
| 91 | int fd=socks->socks[i].fd; |
| 92 | do { |
| 93 | fromlen=sizeof(from); |
| 94 | BUF_ASSERT_FREE(cc->rbuf); |
| 95 | BUF_ALLOC(cc->rbuf,"udp_afterpoll"); |
| 96 | buffer_init(cc->rbuf,calculate_max_start_pad()); |
| 97 | rv=recvfrom(fd, cc->rbuf->start, |
| 98 | buf_remaining_space(cc->rbuf), |
| 99 | 0, &from.sa, &fromlen); |
| 100 | if (rv>0) { |
| 101 | cc->rbuf->size=rv; |
| 102 | if (uc->use_proxy) { |
| 103 | /* Check that the packet came from our poxy server; |
| 104 | we shouldn't be contacted directly by anybody else |
| 105 | (since they can trivially forge source addresses) */ |
| 106 | if (!iaddr_equal(&from,&uc->proxy)) { |
| 107 | Message(M_INFO,"udp: received packet that's not " |
| 108 | "from the proxy\n"); |
| 109 | BUF_FREE(cc->rbuf); |
| 110 | continue; |
| 111 | } |
| 112 | /* proxy protocol supports ipv4 transport only */ |
| 113 | from.sa.sa_family=AF_INET; |
| 114 | BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_addr,4); |
| 115 | buf_unprepend(cc->rbuf,2); |
| 116 | BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_port,2); |
| 117 | } |
| 118 | struct comm_addr ca; |
| 119 | ca.comm=&cc->ops; |
| 120 | ca.ia=from; |
| 121 | ca.ix=i; |
| 122 | done=comm_notify(&cc->notify, cc->rbuf, &ca); |
| 123 | if (!done) { |
| 124 | uint32_t msgtype; |
| 125 | if (cc->rbuf->size>12 /* prevents traffic amplification */ |
| 126 | && ((msgtype=get_uint32(cc->rbuf->start+8)) |
| 127 | != LABEL_NAK)) { |
| 128 | uint32_t source,dest; |
| 129 | /* Manufacture and send NAK packet */ |
| 130 | source=get_uint32(cc->rbuf->start); /* Us */ |
| 131 | dest=get_uint32(cc->rbuf->start+4); /* Them */ |
| 132 | send_nak(&ca,source,dest,msgtype,cc->rbuf,"unwanted"); |
| 133 | } |
| 134 | BUF_FREE(cc->rbuf); |
| 135 | } |
| 136 | BUF_ASSERT_FREE(cc->rbuf); |
| 137 | } else { |
| 138 | BUF_FREE(cc->rbuf); |
| 139 | } |
| 140 | } while (rv>=0); |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | static bool_t udp_sendmsg(void *commst, struct buffer_if *buf, |
| 145 | const struct comm_addr *dest) |
| 146 | { |
| 147 | struct udp *st=commst; |
| 148 | struct udpcommon *uc=&st->uc; |
| 149 | struct udpsocks *socks=&st->socks; |
| 150 | uint8_t *sa; |
| 151 | |
| 152 | if (uc->use_proxy) { |
| 153 | sa=buf_prepend(buf,8); |
| 154 | if (dest->ia.sa.sa_family != AF_INET) { |
| 155 | Message(M_INFO, |
| 156 | "udp: proxy means dropping outgoing non-IPv4 packet to %s\n", |
| 157 | iaddr_to_string(&dest->ia)); |
| 158 | return False; |
| 159 | } |
| 160 | memcpy(sa,&dest->ia.sin.sin_addr,4); |
| 161 | memset(sa+4,0,4); |
| 162 | memcpy(sa+6,&dest->ia.sin.sin_port,2); |
| 163 | sendto(socks->socks[0].fd,sa,buf->size+8,0,&uc->proxy.sa, |
| 164 | iaddr_socklen(&uc->proxy)); |
| 165 | buf_unprepend(buf,8); |
| 166 | } else { |
| 167 | int i,r; |
| 168 | bool_t allunsupported=True; |
| 169 | for (i=0; i<socks->n_socks; i++) { |
| 170 | if (dest->ia.sa.sa_family != socks->socks[i].addr.sa.sa_family) |
| 171 | /* no point even trying */ |
| 172 | continue; |
| 173 | r=sendto(socks->socks[i].fd, buf->start, buf->size, 0, |
| 174 | &dest->ia.sa, iaddr_socklen(&dest->ia)); |
| 175 | if (r>=0) return True; |
| 176 | if (!(errno==EAFNOSUPPORT || errno==ENETUNREACH)) |
| 177 | /* who knows what that error means? */ |
| 178 | allunsupported=False; |
| 179 | } |
| 180 | return !allunsupported; /* see doc for comm_sendmsg_fn in secnet.h */ |
| 181 | } |
| 182 | |
| 183 | return True; |
| 184 | } |
| 185 | |
| 186 | bool_t udp_make_socket(struct udpcommon *uc, struct udpsock *us, |
| 187 | int failmsgclass) |
| 188 | { |
| 189 | const union iaddr *addr=&us->addr; |
| 190 | struct commcommon *cc=&uc->cc; |
| 191 | us->fd=-1; |
| 192 | |
| 193 | #define FAIL_LG 0, cc->cl.description, &cc->loc, failmsgclass |
| 194 | #define FAIL(...) do{ \ |
| 195 | lg_perror(FAIL_LG,errno,__VA_ARGS__); \ |
| 196 | goto failed; \ |
| 197 | }while(0) |
| 198 | |
| 199 | us->fd=socket(addr->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP); |
| 200 | if (us->fd<0) FAIL("socket"); |
| 201 | if (fcntl(us->fd, F_SETFL, fcntl(us->fd, F_GETFL)|O_NONBLOCK)==-1) |
| 202 | FAIL("fcntl(set O_NONBLOCK)"); |
| 203 | setcloexec(us->fd); |
| 204 | #ifdef CONFIG_IPV6 |
| 205 | if (addr->sa.sa_family==AF_INET6) { |
| 206 | int r; |
| 207 | int optval=1; |
| 208 | socklen_t optlen=sizeof(optval); |
| 209 | r=setsockopt(us->fd,IPPROTO_IPV6,IPV6_V6ONLY,&optval,optlen); |
| 210 | if (r) FAIL("setsockopt(,IPV6_V6ONLY,&1,)"); |
| 211 | } |
| 212 | #endif |
| 213 | |
| 214 | if (uc->authbind) { |
| 215 | pid_t c; |
| 216 | int status; |
| 217 | |
| 218 | /* XXX this fork() and waitpid() business needs to be hidden |
| 219 | in some system-specific library functions. */ |
| 220 | c=fork(); |
| 221 | if (c==-1) |
| 222 | FAIL("fork() for authbind"); |
| 223 | if (c==0) { |
| 224 | char *argv[5], addrstr[33], portstr[5]; |
| 225 | const char *addrfam; |
| 226 | int port; |
| 227 | switch (addr->sa.sa_family) { |
| 228 | case AF_INET: |
| 229 | sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr); |
| 230 | port=addr->sin.sin_port; |
| 231 | addrfam=NULL; |
| 232 | break; |
| 233 | #ifdef CONFIG_IPV6 |
| 234 | case AF_INET6: { |
| 235 | int i; |
| 236 | for (i=0; i<16; i++) |
| 237 | sprintf(addrstr+i*2,"%02X",addr->sin6.sin6_addr.s6_addr[i]); |
| 238 | port=addr->sin6.sin6_port; |
| 239 | addrfam="6"; |
| 240 | break; |
| 241 | } |
| 242 | #endif /*CONFIG_IPV6*/ |
| 243 | default: |
| 244 | fatal("udp (%s:%d): unsupported address family for authbind", |
| 245 | cc->loc.file,cc->loc.line); |
| 246 | } |
| 247 | sprintf(portstr,"%04X",port); |
| 248 | argv[0]=uc->authbind; |
| 249 | argv[1]=addrstr; |
| 250 | argv[2]=portstr; |
| 251 | argv[3]=(char*)addrfam; |
| 252 | argv[4]=NULL; |
| 253 | dup2(us->fd,0); |
| 254 | execvp(uc->authbind,argv); |
| 255 | _exit(255); |
| 256 | } |
| 257 | while (waitpid(c,&status,0)==-1) { |
| 258 | if (errno==EINTR) continue; |
| 259 | FAIL("waitpid for authbind"); |
| 260 | } |
| 261 | if (status) { |
| 262 | lg_exitstatus(FAIL_LG,status,"authbind"); |
| 263 | goto failed; |
| 264 | } |
| 265 | } else { |
| 266 | if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0) |
| 267 | FAIL("bind (%s)",iaddr_to_string(addr)); |
| 268 | } |
| 269 | return True; |
| 270 | |
| 271 | failed: |
| 272 | if (us->fd>=0) { |
| 273 | close(us->fd); |
| 274 | us->fd=-1; |
| 275 | } |
| 276 | return False; |
| 277 | |
| 278 | #undef FAIL |
| 279 | } |
| 280 | |
| 281 | void udp_socks_register(struct udpcommon *uc, struct udpsocks *socks) |
| 282 | { |
| 283 | socks->uc=uc; |
| 284 | socks->interest= |
| 285 | register_for_poll(socks,udp_socks_beforepoll,udp_socks_afterpoll,"udp"); |
| 286 | } |
| 287 | |
| 288 | void udp_socks_deregister(struct udpcommon *uc, struct udpsocks *socks) |
| 289 | { |
| 290 | socks->uc=uc; |
| 291 | deregister_for_poll(socks->interest); |
| 292 | } |
| 293 | |
| 294 | static void udp_phase_hook(void *sst, uint32_t new_phase) |
| 295 | { |
| 296 | struct udp *st=sst; |
| 297 | struct udpsocks *socks=&st->socks; |
| 298 | struct udpcommon *uc=&st->uc; |
| 299 | int i; |
| 300 | for (i=0; i<socks->n_socks; i++) |
| 301 | udp_make_socket(uc,&socks->socks[i],M_FATAL); |
| 302 | |
| 303 | udp_socks_register(uc,socks); |
| 304 | } |
| 305 | |
| 306 | static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context, |
| 307 | list_t *args) |
| 308 | { |
| 309 | struct udp *st; |
| 310 | list_t *caddrl; |
| 311 | list_t *l; |
| 312 | uint32_t a; |
| 313 | int i; |
| 314 | |
| 315 | COMM_APPLY(st,&st->uc.cc,udp_,"udp",loc); |
| 316 | COMM_APPLY_STANDARD(st,&st->uc.cc,"udp",args); |
| 317 | UDP_APPLY_STANDARD(st,&st->uc,"udp"); |
| 318 | |
| 319 | struct udpcommon *uc=&st->uc; |
| 320 | struct udpsocks *socks=&st->socks; |
| 321 | struct commcommon *cc=&uc->cc; |
| 322 | |
| 323 | union iaddr defaultaddrs[] = { |
| 324 | #ifdef CONFIG_IPV6 |
| 325 | { .sin6 = { .sin6_family=AF_INET6, |
| 326 | .sin6_port=htons(uc->port), |
| 327 | .sin6_addr=IN6ADDR_ANY_INIT } }, |
| 328 | #endif |
| 329 | { .sin = { .sin_family=AF_INET, |
| 330 | .sin_port=htons(uc->port), |
| 331 | .sin_addr= { .s_addr=INADDR_ANY } } } |
| 332 | }; |
| 333 | |
| 334 | caddrl=dict_lookup(d,"address"); |
| 335 | socks->n_socks=caddrl ? list_length(caddrl) : (int)ARRAY_SIZE(defaultaddrs); |
| 336 | if (socks->n_socks<=0 || socks->n_socks>UDP_MAX_SOCKETS) |
| 337 | cfgfatal(cc->loc,"udp","`address' must be 1..%d addresses", |
| 338 | UDP_MAX_SOCKETS); |
| 339 | |
| 340 | for (i=0; i<socks->n_socks; i++) { |
| 341 | struct udpsock *us=&socks->socks[i]; |
| 342 | if (!list_length(caddrl)) { |
| 343 | us->addr=defaultaddrs[i]; |
| 344 | } else { |
| 345 | string_item_to_iaddr(list_elem(caddrl,i),uc->port,&us->addr,"udp"); |
| 346 | } |
| 347 | us->fd=-1; |
| 348 | } |
| 349 | |
| 350 | l=dict_lookup(d,"proxy"); |
| 351 | if (l) { |
| 352 | uc->use_proxy=True; |
| 353 | uc->proxy.sa.sa_family=AF_INET; |
| 354 | item=list_elem(l,0); |
| 355 | if (!item || item->type!=t_string) { |
| 356 | cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n"); |
| 357 | } |
| 358 | a=string_item_to_ipaddr(item,"proxy"); |
| 359 | uc->proxy.sin.sin_addr.s_addr=htonl(a); |
| 360 | item=list_elem(l,1); |
| 361 | if (!item || item->type!=t_number) { |
| 362 | cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n"); |
| 363 | } |
| 364 | uc->proxy.sin.sin_port=htons(item->data.number); |
| 365 | } |
| 366 | |
| 367 | update_max_start_pad(&comm_max_start_pad, uc->use_proxy ? 8 : 0); |
| 368 | |
| 369 | add_hook(PHASE_GETRESOURCES,udp_phase_hook,st); |
| 370 | |
| 371 | return new_closure(&cc->cl); |
| 372 | } |
| 373 | |
| 374 | void udp_module(dict_t *dict) |
| 375 | { |
| 376 | add_closure(dict,"udp",udp_apply); |
| 377 | } |