| 1 | /* $Cambridge: exim/src/src/ip.c,v 1.3 2005/06/27 14:29:43 ph10 Exp $ */ |
| 2 | |
| 3 | /************************************************* |
| 4 | * Exim - an Internet mail transport agent * |
| 5 | *************************************************/ |
| 6 | |
| 7 | /* Copyright (c) University of Cambridge 1995 - 2005 */ |
| 8 | /* See the file NOTICE for conditions of use and distribution. */ |
| 9 | |
| 10 | /* Functions for doing things with sockets. With the advent of IPv6 this has |
| 11 | got messier, so that it's worth pulling out the code into separate functions |
| 12 | that other parts of Exim can call, expecially as there are now several |
| 13 | different places in the code where sockets are used. */ |
| 14 | |
| 15 | |
| 16 | #include "exim.h" |
| 17 | |
| 18 | |
| 19 | /************************************************* |
| 20 | * Create a socket * |
| 21 | *************************************************/ |
| 22 | |
| 23 | /* Socket creation happens in a number of places so it's packaged here for |
| 24 | convenience. |
| 25 | |
| 26 | Arguments: |
| 27 | type SOCK_DGRAM or SOCK_STREAM |
| 28 | af AF_INET or AF_INET6 |
| 29 | |
| 30 | Returns: socket number or -1 on failure |
| 31 | */ |
| 32 | |
| 33 | int |
| 34 | ip_socket(int type, int af) |
| 35 | { |
| 36 | int sock = socket(af, type, 0); |
| 37 | if (sock < 0) |
| 38 | log_write(0, LOG_MAIN, "IPv%c socket creation failed: %s", |
| 39 | (af == AF_INET6)? '6':'4', strerror(errno)); |
| 40 | return sock; |
| 41 | } |
| 42 | |
| 43 | |
| 44 | |
| 45 | |
| 46 | #if HAVE_IPV6 |
| 47 | /************************************************* |
| 48 | * Convert printing address to numeric * |
| 49 | *************************************************/ |
| 50 | |
| 51 | /* This function converts the textual form of an IP address into a numeric form |
| 52 | in an appropriate structure in an IPv6 environment. The getaddrinfo() function |
| 53 | can (apparently) handle more complicated addresses (e.g. those containing |
| 54 | scopes) than inet_pton() in some environments. We use hints to tell it that the |
| 55 | input must be a numeric address. |
| 56 | |
| 57 | However, apparently some operating systems (or libraries) don't support |
| 58 | getaddrinfo(), so there is a build-time option to revert to inet_pton() (which |
| 59 | does not support scopes). |
| 60 | |
| 61 | Arguments: |
| 62 | address textual form of the address |
| 63 | addr where to copy back the answer |
| 64 | |
| 65 | Returns: nothing - failure provokes a panic-die |
| 66 | */ |
| 67 | |
| 68 | static void |
| 69 | ip_addrinfo(uschar *address, struct sockaddr_in6 *saddr) |
| 70 | { |
| 71 | #ifdef IPV6_USE_INET_PTON |
| 72 | |
| 73 | if (inet_pton(AF_INET6, CS address, &saddr->sin6_addr) != 1) |
| 74 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an " |
| 75 | "IP address", address); |
| 76 | saddr->sin6_family = AF_INET6; |
| 77 | |
| 78 | #else |
| 79 | |
| 80 | int rc; |
| 81 | struct addrinfo hints, *res; |
| 82 | memset(&hints, 0, sizeof(hints)); |
| 83 | hints.ai_family = AF_INET6; |
| 84 | hints.ai_socktype = SOCK_STREAM; |
| 85 | hints.ai_flags = AI_NUMERICHOST; |
| 86 | if ((rc = getaddrinfo(CS address, NULL, &hints, &res)) != 0 || res == NULL) |
| 87 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an " |
| 88 | "IP address: %s", address, |
| 89 | (rc == 0)? "NULL result returned" : gai_strerror(rc)); |
| 90 | memcpy(saddr, res->ai_addr, res->ai_addrlen); |
| 91 | freeaddrinfo(res); |
| 92 | |
| 93 | #endif |
| 94 | } |
| 95 | #endif /* HAVE_IPV6 */ |
| 96 | |
| 97 | |
| 98 | /************************************************* |
| 99 | * Bind socket to interface and port * |
| 100 | *************************************************/ |
| 101 | |
| 102 | /* This function binds a socket to a local interface address and port. For a |
| 103 | wildcard IPv6 bind, the address is ":". |
| 104 | |
| 105 | Arguments: |
| 106 | sock the socket |
| 107 | af AF_INET or AF_INET6 - the socket type |
| 108 | address the IP address, in text form |
| 109 | port the IP port (host order) |
| 110 | |
| 111 | Returns: the result of bind() |
| 112 | */ |
| 113 | |
| 114 | int |
| 115 | ip_bind(int sock, int af, uschar *address, int port) |
| 116 | { |
| 117 | int s_len; |
| 118 | union sockaddr_46 sin; |
| 119 | memset(&sin, 0, sizeof(sin)); |
| 120 | |
| 121 | /* Setup code when using an IPv6 socket. The wildcard address is ":", to |
| 122 | ensure an IPv6 socket is used. */ |
| 123 | |
| 124 | #if HAVE_IPV6 |
| 125 | if (af == AF_INET6) |
| 126 | { |
| 127 | if (address[0] == ':' && address[1] == 0) |
| 128 | { |
| 129 | sin.v6.sin6_family = AF_INET6; |
| 130 | sin.v6.sin6_addr = in6addr_any; |
| 131 | } |
| 132 | else |
| 133 | { |
| 134 | ip_addrinfo(address, &sin.v6); /* Panic-dies on error */ |
| 135 | } |
| 136 | sin.v6.sin6_port = htons(port); |
| 137 | s_len = sizeof(sin.v6); |
| 138 | } |
| 139 | else |
| 140 | #else /* HAVE_IPv6 */ |
| 141 | af = af; /* Avoid compiler warning */ |
| 142 | #endif /* HAVE_IPV6 */ |
| 143 | |
| 144 | /* Setup code when using IPv4 socket. The wildcard address is "". */ |
| 145 | |
| 146 | { |
| 147 | sin.v4.sin_family = AF_INET; |
| 148 | sin.v4.sin_port = htons(port); |
| 149 | s_len = sizeof(sin.v4); |
| 150 | if (address[0] == 0) |
| 151 | sin.v4.sin_addr.s_addr = (S_ADDR_TYPE)INADDR_ANY; |
| 152 | else |
| 153 | sin.v4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CS address); |
| 154 | } |
| 155 | |
| 156 | /* Now we can call the bind() function */ |
| 157 | |
| 158 | return bind(sock, (struct sockaddr *)&sin, s_len); |
| 159 | } |
| 160 | |
| 161 | |
| 162 | |
| 163 | /************************************************* |
| 164 | * Connect socket to remote host * |
| 165 | *************************************************/ |
| 166 | |
| 167 | /* This function connects a socket to a remote address and port. The socket may |
| 168 | or may not have previously been bound to a local interface. |
| 169 | |
| 170 | Arguments: |
| 171 | sock the socket |
| 172 | af AF_INET6 or AF_INET for the socket type |
| 173 | address the remote address, in text form |
| 174 | port the remote port |
| 175 | timeout a timeout |
| 176 | |
| 177 | Returns: 0 on success; -1 on failure, with errno set |
| 178 | */ |
| 179 | |
| 180 | int |
| 181 | ip_connect(int sock, int af, uschar *address, int port, int timeout) |
| 182 | { |
| 183 | struct sockaddr_in s_in4; |
| 184 | struct sockaddr *s_ptr; |
| 185 | int s_len, rc, save_errno; |
| 186 | |
| 187 | /* For an IPv6 address, use an IPv6 sockaddr structure. */ |
| 188 | |
| 189 | #if HAVE_IPV6 |
| 190 | struct sockaddr_in6 s_in6; |
| 191 | if (af == AF_INET6) |
| 192 | { |
| 193 | memset(&s_in6, 0, sizeof(s_in6)); |
| 194 | ip_addrinfo(address, &s_in6); /* Panic-dies on error */ |
| 195 | s_in6.sin6_port = htons(port); |
| 196 | s_ptr = (struct sockaddr *)&s_in6; |
| 197 | s_len = sizeof(s_in6); |
| 198 | } |
| 199 | else |
| 200 | #else /* HAVE_IPV6 */ |
| 201 | af = af; /* Avoid compiler warning */ |
| 202 | #endif /* HAVE_IPV6 */ |
| 203 | |
| 204 | /* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with |
| 205 | IPv6 support. */ |
| 206 | |
| 207 | { |
| 208 | memset(&s_in4, 0, sizeof(s_in4)); |
| 209 | s_in4.sin_family = AF_INET; |
| 210 | s_in4.sin_port = htons(port); |
| 211 | s_in4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CS address); |
| 212 | s_ptr = (struct sockaddr *)&s_in4; |
| 213 | s_len = sizeof(s_in4); |
| 214 | } |
| 215 | |
| 216 | /* If no connection timeout is set, just call connect() without setting a |
| 217 | timer, thereby allowing the inbuilt OS timeout to operate. */ |
| 218 | |
| 219 | sigalrm_seen = FALSE; |
| 220 | if (timeout > 0) alarm(timeout); |
| 221 | rc = connect(sock, s_ptr, s_len); |
| 222 | save_errno = errno; |
| 223 | alarm(0); |
| 224 | |
| 225 | /* There is a testing facility for simulating a connection timeout, as I |
| 226 | can't think of any other way of doing this. It converts a connection refused |
| 227 | into a timeout. |
| 228 | |
| 229 | I had to add a second fudge to keep the tests working. Attempts to connect to |
| 230 | 10.x.x.x are expected to timeout, but sometimes they now give "No route to |
| 231 | host". */ |
| 232 | |
| 233 | if (running_in_test_harness) |
| 234 | { |
| 235 | if ((save_errno == ECONNREFUSED && timeout == 999999) || |
| 236 | (save_errno == EHOSTUNREACH && timeout > 0 && |
| 237 | Ustrncmp(address, "10.", 3) == 0)) |
| 238 | { |
| 239 | rc = -1; |
| 240 | save_errno = EINTR; |
| 241 | sigalrm_seen = TRUE; |
| 242 | } |
| 243 | } |
| 244 | |
| 245 | /* Success */ |
| 246 | |
| 247 | if (rc >= 0) return 0; |
| 248 | |
| 249 | /* A failure whose error code is "Interrupted system call" is in fact |
| 250 | an externally applied timeout if the signal handler has been run. */ |
| 251 | |
| 252 | (void)close(sock); |
| 253 | errno = (save_errno == EINTR && sigalrm_seen)? ETIMEDOUT : save_errno; |
| 254 | return -1; |
| 255 | } |
| 256 | |
| 257 | |
| 258 | |
| 259 | /************************************************* |
| 260 | * Set keepalive on a socket * |
| 261 | *************************************************/ |
| 262 | |
| 263 | /* Can be called for both incoming and outgoing sockets. |
| 264 | |
| 265 | Arguments: |
| 266 | sock the socket |
| 267 | address the remote host address, for failure logging |
| 268 | torf true for outgoing connection, false for incoming |
| 269 | |
| 270 | Returns: nothing |
| 271 | */ |
| 272 | |
| 273 | void |
| 274 | ip_keepalive(int sock, uschar *address, BOOL torf) |
| 275 | { |
| 276 | int fodder = 1; |
| 277 | if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, |
| 278 | (uschar *)(&fodder), sizeof(fodder)) != 0) |
| 279 | log_write(0, LOG_MAIN, "setsockopt(SO_KEEPALIVE) on connection %s %s " |
| 280 | "failed: %s", torf? "to":"from", address, strerror(errno)); |
| 281 | } |
| 282 | |
| 283 | |
| 284 | |
| 285 | /************************************************* |
| 286 | * Receive from a socket with timeout * |
| 287 | *************************************************/ |
| 288 | |
| 289 | /* The timeout is implemented using select(), and we loop to cover select() |
| 290 | getting interrupted, and the possibility of select() returning with a positive |
| 291 | result but no ready descriptor. Is this in fact possible? |
| 292 | |
| 293 | Arguments: |
| 294 | sock the socket |
| 295 | buffer to read into |
| 296 | bufsize the buffer size |
| 297 | timeout the timeout |
| 298 | |
| 299 | Returns: > 0 => that much data read |
| 300 | <= 0 on error or EOF; errno set - zero for EOF |
| 301 | */ |
| 302 | |
| 303 | int |
| 304 | ip_recv(int sock, uschar *buffer, int buffsize, int timeout) |
| 305 | { |
| 306 | fd_set select_inset; |
| 307 | struct timeval tv; |
| 308 | int start_recv = time(NULL); |
| 309 | int rc; |
| 310 | |
| 311 | /* Wait until the socket is ready */ |
| 312 | |
| 313 | for (;;) |
| 314 | { |
| 315 | FD_ZERO (&select_inset); |
| 316 | FD_SET (sock, &select_inset); |
| 317 | tv.tv_sec = timeout; |
| 318 | tv.tv_usec = 0; |
| 319 | |
| 320 | DEBUG(D_transport) debug_printf("waiting for data on socket\n"); |
| 321 | rc = select(sock + 1, (SELECT_ARG2_TYPE *)&select_inset, NULL, NULL, &tv); |
| 322 | |
| 323 | /* If some interrupt arrived, just retry. We presume this to be rare, |
| 324 | but it can happen (e.g. the SIGUSR1 signal sent by exiwhat causes |
| 325 | select() to exit). |
| 326 | |
| 327 | Aug 2004: Somebody set up a cron job that ran exiwhat every 2 minutes, making |
| 328 | the interrupt not at all rare. Since the timeout is typically more than 2 |
| 329 | minutes, the effect was to block the timeout completely. To prevent this |
| 330 | happening again, we do an explicit time test. */ |
| 331 | |
| 332 | if (rc < 0 && errno == EINTR) |
| 333 | { |
| 334 | DEBUG(D_transport) debug_printf("EINTR while waiting for socket data\n"); |
| 335 | if (time(NULL) - start_recv < timeout) continue; |
| 336 | DEBUG(D_transport) debug_printf("total wait time exceeds timeout\n"); |
| 337 | } |
| 338 | |
| 339 | /* Handle a timeout, and treat any other select error as a timeout, including |
| 340 | an EINTR when we have been in this loop for longer than timeout. */ |
| 341 | |
| 342 | if (rc <= 0) |
| 343 | { |
| 344 | errno = ETIMEDOUT; |
| 345 | return -1; |
| 346 | } |
| 347 | |
| 348 | /* If the socket is ready, break out of the loop. */ |
| 349 | |
| 350 | if (FD_ISSET(sock, &select_inset)) break; |
| 351 | } |
| 352 | |
| 353 | /* The socket is ready, read from it (via TLS if it's active). On EOF (i.e. |
| 354 | close down of the connection), set errno to zero; otherwise leave it alone. */ |
| 355 | |
| 356 | #ifdef SUPPORT_TLS |
| 357 | if (tls_active == sock) |
| 358 | rc = tls_read(buffer, buffsize); |
| 359 | else |
| 360 | #endif |
| 361 | rc = recv(sock, buffer, buffsize, 0); |
| 362 | |
| 363 | if (rc > 0) return rc; |
| 364 | if (rc == 0) errno = 0; |
| 365 | return -1; |
| 366 | } |
| 367 | |
| 368 | |
| 369 | /* End of ip.c */ |