| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge 1995 - 2009 */ |
| 6 | /* See the file NOTICE for conditions of use and distribution. */ |
| 7 | |
| 8 | /* A number of functions for driving outgoing SMTP calls. */ |
| 9 | |
| 10 | |
| 11 | #include "exim.h" |
| 12 | |
| 13 | |
| 14 | |
| 15 | /************************************************* |
| 16 | * Find an outgoing interface * |
| 17 | *************************************************/ |
| 18 | |
| 19 | /* This function is called from the smtp transport and also from the callout |
| 20 | code in verify.c. Its job is to expand a string to get a list of interfaces, |
| 21 | and choose a suitable one (IPv4 or IPv6) for the outgoing address. |
| 22 | |
| 23 | Arguments: |
| 24 | istring string interface setting, may be NULL, meaning "any", in |
| 25 | which case the function does nothing |
| 26 | host_af AF_INET or AF_INET6 for the outgoing IP address |
| 27 | addr the mail address being handled (for setting errors) |
| 28 | changed if not NULL, set TRUE if expansion actually changed istring |
| 29 | interface point this to the interface |
| 30 | msg to add to any error message |
| 31 | |
| 32 | Returns: TRUE on success, FALSE on failure, with error message |
| 33 | set in addr and transport_return set to PANIC |
| 34 | */ |
| 35 | |
| 36 | BOOL |
| 37 | smtp_get_interface(uschar *istring, int host_af, address_item *addr, |
| 38 | BOOL *changed, uschar **interface, uschar *msg) |
| 39 | { |
| 40 | uschar *expint; |
| 41 | uschar *iface; |
| 42 | int sep = 0; |
| 43 | |
| 44 | if (istring == NULL) return TRUE; |
| 45 | |
| 46 | expint = expand_string(istring); |
| 47 | if (expint == NULL) |
| 48 | { |
| 49 | if (expand_string_forcedfail) return TRUE; |
| 50 | addr->transport_return = PANIC; |
| 51 | addr->message = string_sprintf("failed to expand \"interface\" " |
| 52 | "option for %s: %s", msg, expand_string_message); |
| 53 | return FALSE; |
| 54 | } |
| 55 | |
| 56 | if (changed != NULL) *changed = expint != istring; |
| 57 | |
| 58 | while (isspace(*expint)) expint++; |
| 59 | if (*expint == 0) return TRUE; |
| 60 | |
| 61 | while ((iface = string_nextinlist(&expint, &sep, big_buffer, |
| 62 | big_buffer_size)) != NULL) |
| 63 | { |
| 64 | if (string_is_ip_address(iface, NULL) == 0) |
| 65 | { |
| 66 | addr->transport_return = PANIC; |
| 67 | addr->message = string_sprintf("\"%s\" is not a valid IP " |
| 68 | "address for the \"interface\" option for %s", |
| 69 | iface, msg); |
| 70 | return FALSE; |
| 71 | } |
| 72 | |
| 73 | if (((Ustrchr(iface, ':') == NULL)? AF_INET:AF_INET6) == host_af) |
| 74 | break; |
| 75 | } |
| 76 | |
| 77 | if (iface != NULL) *interface = string_copy(iface); |
| 78 | return TRUE; |
| 79 | } |
| 80 | |
| 81 | |
| 82 | |
| 83 | /************************************************* |
| 84 | * Find an outgoing port * |
| 85 | *************************************************/ |
| 86 | |
| 87 | /* This function is called from the smtp transport and also from the callout |
| 88 | code in verify.c. Its job is to find a port number. Note that getservbyname() |
| 89 | produces the number in network byte order. |
| 90 | |
| 91 | Arguments: |
| 92 | rstring raw (unexpanded) string representation of the port |
| 93 | addr the mail address being handled (for setting errors) |
| 94 | port stick the port in here |
| 95 | msg for adding to error message |
| 96 | |
| 97 | Returns: TRUE on success, FALSE on failure, with error message set |
| 98 | in addr, and transport_return set to PANIC |
| 99 | */ |
| 100 | |
| 101 | BOOL |
| 102 | smtp_get_port(uschar *rstring, address_item *addr, int *port, uschar *msg) |
| 103 | { |
| 104 | uschar *pstring = expand_string(rstring); |
| 105 | |
| 106 | if (pstring == NULL) |
| 107 | { |
| 108 | addr->transport_return = PANIC; |
| 109 | addr->message = string_sprintf("failed to expand \"%s\" (\"port\" option) " |
| 110 | "for %s: %s", rstring, msg, expand_string_message); |
| 111 | return FALSE; |
| 112 | } |
| 113 | |
| 114 | if (isdigit(*pstring)) |
| 115 | { |
| 116 | uschar *end; |
| 117 | *port = Ustrtol(pstring, &end, 0); |
| 118 | if (end != pstring + Ustrlen(pstring)) |
| 119 | { |
| 120 | addr->transport_return = PANIC; |
| 121 | addr->message = string_sprintf("invalid port number for %s: %s", msg, |
| 122 | pstring); |
| 123 | return FALSE; |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | else |
| 128 | { |
| 129 | struct servent *smtp_service = getservbyname(CS pstring, "tcp"); |
| 130 | if (smtp_service == NULL) |
| 131 | { |
| 132 | addr->transport_return = PANIC; |
| 133 | addr->message = string_sprintf("TCP port \"%s\" is not defined for %s", |
| 134 | pstring, msg); |
| 135 | return FALSE; |
| 136 | } |
| 137 | *port = ntohs(smtp_service->s_port); |
| 138 | } |
| 139 | |
| 140 | return TRUE; |
| 141 | } |
| 142 | |
| 143 | |
| 144 | |
| 145 | |
| 146 | /************************************************* |
| 147 | * Connect to remote host * |
| 148 | *************************************************/ |
| 149 | |
| 150 | /* Create a socket, and connect it to a remote host. IPv6 addresses are |
| 151 | detected by checking for a colon in the address. AF_INET6 is defined even on |
| 152 | non-IPv6 systems, to enable the code to be less messy. However, on such systems |
| 153 | host->address will always be an IPv4 address. |
| 154 | |
| 155 | The port field in the host item is used if it is set (usually router from SRV |
| 156 | records or elsewhere). In other cases, the default passed as an argument is |
| 157 | used, and the host item is updated with its value. |
| 158 | |
| 159 | Arguments: |
| 160 | host host item containing name and address (and sometimes port) |
| 161 | host_af AF_INET or AF_INET6 |
| 162 | port default remote port to connect to, in host byte order, for those |
| 163 | hosts whose port setting is PORT_NONE |
| 164 | interface outgoing interface address or NULL |
| 165 | timeout timeout value or 0 |
| 166 | keepalive TRUE to use keepalive |
| 167 | |
| 168 | Returns: connected socket number, or -1 with errno set |
| 169 | */ |
| 170 | |
| 171 | int |
| 172 | smtp_connect(host_item *host, int host_af, int port, uschar *interface, |
| 173 | int timeout, BOOL keepalive) |
| 174 | { |
| 175 | int on = 1; |
| 176 | int save_errno = 0; |
| 177 | int sock; |
| 178 | |
| 179 | if (host->port != PORT_NONE) |
| 180 | { |
| 181 | HDEBUG(D_transport|D_acl|D_v) |
| 182 | debug_printf("Transport port=%d replaced by host-specific port=%d\n", port, |
| 183 | host->port); |
| 184 | port = host->port; |
| 185 | } |
| 186 | else host->port = port; /* Set the port actually used */ |
| 187 | |
| 188 | HDEBUG(D_transport|D_acl|D_v) |
| 189 | { |
| 190 | if (interface == NULL) |
| 191 | debug_printf("Connecting to %s [%s]:%d ... ",host->name,host->address,port); |
| 192 | else |
| 193 | debug_printf("Connecting to %s [%s]:%d from %s ... ", host->name, |
| 194 | host->address, port, interface); |
| 195 | } |
| 196 | |
| 197 | /* Create the socket */ |
| 198 | |
| 199 | if ((sock = ip_socket(SOCK_STREAM, host_af)) < 0) return -1; |
| 200 | |
| 201 | /* Set TCP_NODELAY; Exim does its own buffering. */ |
| 202 | |
| 203 | setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (uschar *)(&on), sizeof(on)); |
| 204 | |
| 205 | /* Bind to a specific interface if requested. Caller must ensure the interface |
| 206 | is the same type (IPv4 or IPv6) as the outgoing address. */ |
| 207 | |
| 208 | if (interface != NULL && ip_bind(sock, host_af, interface, 0) < 0) |
| 209 | { |
| 210 | save_errno = errno; |
| 211 | HDEBUG(D_transport|D_acl|D_v) |
| 212 | debug_printf("unable to bind outgoing SMTP call to %s: %s", interface, |
| 213 | strerror(errno)); |
| 214 | } |
| 215 | |
| 216 | /* Connect to the remote host, and add keepalive to the socket before returning |
| 217 | it, if requested. */ |
| 218 | |
| 219 | else if (ip_connect(sock, host_af, host->address, port, timeout) < 0) |
| 220 | save_errno = errno; |
| 221 | |
| 222 | /* Either bind() or connect() failed */ |
| 223 | |
| 224 | if (save_errno != 0) |
| 225 | { |
| 226 | HDEBUG(D_transport|D_acl|D_v) |
| 227 | { |
| 228 | debug_printf("failed: %s", CUstrerror(save_errno)); |
| 229 | if (save_errno == ETIMEDOUT) |
| 230 | debug_printf(" (timeout=%s)", readconf_printtime(timeout)); |
| 231 | debug_printf("\n"); |
| 232 | } |
| 233 | (void)close(sock); |
| 234 | errno = save_errno; |
| 235 | return -1; |
| 236 | } |
| 237 | |
| 238 | /* Both bind() and connect() succeeded */ |
| 239 | |
| 240 | else |
| 241 | { |
| 242 | union sockaddr_46 interface_sock; |
| 243 | EXIM_SOCKLEN_T size = sizeof(interface_sock); |
| 244 | HDEBUG(D_transport|D_acl|D_v) debug_printf("connected\n"); |
| 245 | if (getsockname(sock, (struct sockaddr *)(&interface_sock), &size) == 0) |
| 246 | sending_ip_address = host_ntoa(-1, &interface_sock, NULL, &sending_port); |
| 247 | else |
| 248 | { |
| 249 | log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC), |
| 250 | "getsockname() failed: %s", strerror(errno)); |
| 251 | close(sock); |
| 252 | return -1; |
| 253 | } |
| 254 | if (keepalive) ip_keepalive(sock, host->address, TRUE); |
| 255 | return sock; |
| 256 | } |
| 257 | } |
| 258 | |
| 259 | |
| 260 | /************************************************* |
| 261 | * Flush outgoing command buffer * |
| 262 | *************************************************/ |
| 263 | |
| 264 | /* This function is called only from smtp_write_command() below. It flushes |
| 265 | the buffer of outgoing commands. There is more than one in the buffer only when |
| 266 | pipelining. |
| 267 | |
| 268 | Argument: |
| 269 | outblock the SMTP output block |
| 270 | |
| 271 | Returns: TRUE if OK, FALSE on error, with errno set |
| 272 | */ |
| 273 | |
| 274 | static BOOL |
| 275 | flush_buffer(smtp_outblock *outblock) |
| 276 | { |
| 277 | int rc; |
| 278 | |
| 279 | #ifdef SUPPORT_TLS |
| 280 | if (tls_active == outblock->sock) |
| 281 | rc = tls_write(outblock->buffer, outblock->ptr - outblock->buffer); |
| 282 | else |
| 283 | #endif |
| 284 | |
| 285 | rc = send(outblock->sock, outblock->buffer, outblock->ptr - outblock->buffer, 0); |
| 286 | if (rc <= 0) |
| 287 | { |
| 288 | HDEBUG(D_transport|D_acl) debug_printf("send failed: %s\n", strerror(errno)); |
| 289 | return FALSE; |
| 290 | } |
| 291 | |
| 292 | outblock->ptr = outblock->buffer; |
| 293 | outblock->cmd_count = 0; |
| 294 | return TRUE; |
| 295 | } |
| 296 | |
| 297 | |
| 298 | |
| 299 | /************************************************* |
| 300 | * Write SMTP command * |
| 301 | *************************************************/ |
| 302 | |
| 303 | /* The formatted command is left in big_buffer so that it can be reflected in |
| 304 | any error message. |
| 305 | |
| 306 | Arguments: |
| 307 | outblock contains buffer for pipelining, and socket |
| 308 | noflush if TRUE, save the command in the output buffer, for pipelining |
| 309 | format a format, starting with one of |
| 310 | of HELO, MAIL FROM, RCPT TO, DATA, ".", or QUIT. |
| 311 | ... data for the format |
| 312 | |
| 313 | Returns: 0 if command added to pipelining buffer, with nothing transmitted |
| 314 | +n if n commands transmitted (may still have buffered the new one) |
| 315 | -1 on error, with errno set |
| 316 | */ |
| 317 | |
| 318 | int |
| 319 | smtp_write_command(smtp_outblock *outblock, BOOL noflush, const char *format, ...) |
| 320 | { |
| 321 | int count; |
| 322 | int rc = 0; |
| 323 | va_list ap; |
| 324 | |
| 325 | va_start(ap, format); |
| 326 | if (!string_vformat(big_buffer, big_buffer_size, CS format, ap)) |
| 327 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing " |
| 328 | "SMTP"); |
| 329 | va_end(ap); |
| 330 | count = Ustrlen(big_buffer); |
| 331 | |
| 332 | if (count > outblock->buffersize - (outblock->ptr - outblock->buffer)) |
| 333 | { |
| 334 | rc = outblock->cmd_count; /* flush resets */ |
| 335 | if (!flush_buffer(outblock)) return -1; |
| 336 | } |
| 337 | |
| 338 | Ustrncpy(CS outblock->ptr, big_buffer, count); |
| 339 | outblock->ptr += count; |
| 340 | outblock->cmd_count++; |
| 341 | count -= 2; |
| 342 | big_buffer[count] = 0; /* remove \r\n for error message */ |
| 343 | |
| 344 | /* We want to hide the actual data sent in AUTH transactions from reflections |
| 345 | and logs. While authenticating, a flag is set in the outblock to enable this. |
| 346 | The AUTH command itself gets any data flattened. Other lines are flattened |
| 347 | completely. */ |
| 348 | |
| 349 | if (outblock->authenticating) |
| 350 | { |
| 351 | uschar *p = big_buffer; |
| 352 | if (Ustrncmp(big_buffer, "AUTH ", 5) == 0) |
| 353 | { |
| 354 | p += 5; |
| 355 | while (isspace(*p)) p++; |
| 356 | while (!isspace(*p)) p++; |
| 357 | while (isspace(*p)) p++; |
| 358 | } |
| 359 | while (*p != 0) *p++ = '*'; |
| 360 | } |
| 361 | |
| 362 | HDEBUG(D_transport|D_acl|D_v) debug_printf(" SMTP>> %s\n", big_buffer); |
| 363 | |
| 364 | if (!noflush) |
| 365 | { |
| 366 | rc += outblock->cmd_count; /* flush resets */ |
| 367 | if (!flush_buffer(outblock)) return -1; |
| 368 | } |
| 369 | |
| 370 | return rc; |
| 371 | } |
| 372 | |
| 373 | |
| 374 | |
| 375 | /************************************************* |
| 376 | * Read one line of SMTP response * |
| 377 | *************************************************/ |
| 378 | |
| 379 | /* This function reads one line of SMTP response from the server host. This may |
| 380 | not be a complete response - it could be just part of a multiline response. We |
| 381 | have to use a buffer for incoming packets, because when pipelining or using |
| 382 | LMTP, there may well be more than one response in a single packet. This |
| 383 | function is called only from the one that follows. |
| 384 | |
| 385 | Arguments: |
| 386 | inblock the SMTP input block (contains holding buffer, socket, etc.) |
| 387 | buffer where to put the line |
| 388 | size space available for the line |
| 389 | timeout the timeout to use when reading a packet |
| 390 | |
| 391 | Returns: length of a line that has been put in the buffer |
| 392 | -1 otherwise, with errno set |
| 393 | */ |
| 394 | |
| 395 | static int |
| 396 | read_response_line(smtp_inblock *inblock, uschar *buffer, int size, int timeout) |
| 397 | { |
| 398 | uschar *p = buffer; |
| 399 | uschar *ptr = inblock->ptr; |
| 400 | uschar *ptrend = inblock->ptrend; |
| 401 | int sock = inblock->sock; |
| 402 | |
| 403 | /* Loop for reading multiple packets or reading another packet after emptying |
| 404 | a previously-read one. */ |
| 405 | |
| 406 | for (;;) |
| 407 | { |
| 408 | int rc; |
| 409 | |
| 410 | /* If there is data in the input buffer left over from last time, copy |
| 411 | characters from it until the end of a line, at which point we can return, |
| 412 | having removed any whitespace (which will include CR) at the end of the line. |
| 413 | The rules for SMTP say that lines end in CRLF, but there are have been cases |
| 414 | of hosts using just LF, and other MTAs are reported to handle this, so we |
| 415 | just look for LF. If we run out of characters before the end of a line, |
| 416 | carry on to read the next incoming packet. */ |
| 417 | |
| 418 | while (ptr < ptrend) |
| 419 | { |
| 420 | int c = *ptr++; |
| 421 | if (c == '\n') |
| 422 | { |
| 423 | while (p > buffer && isspace(p[-1])) p--; |
| 424 | *p = 0; |
| 425 | inblock->ptr = ptr; |
| 426 | return p - buffer; |
| 427 | } |
| 428 | *p++ = c; |
| 429 | if (--size < 4) |
| 430 | { |
| 431 | *p = 0; /* Leave malformed line for error message */ |
| 432 | errno = ERRNO_SMTPFORMAT; |
| 433 | return -1; |
| 434 | } |
| 435 | } |
| 436 | |
| 437 | /* Need to read a new input packet. */ |
| 438 | |
| 439 | rc = ip_recv(sock, inblock->buffer, inblock->buffersize, timeout); |
| 440 | if (rc <= 0) break; |
| 441 | |
| 442 | /* Another block of data has been successfully read. Set up the pointers |
| 443 | and let the loop continue. */ |
| 444 | |
| 445 | ptrend = inblock->ptrend = inblock->buffer + rc; |
| 446 | ptr = inblock->buffer; |
| 447 | DEBUG(D_transport|D_acl) debug_printf("read response data: size=%d\n", rc); |
| 448 | } |
| 449 | |
| 450 | /* Get here if there has been some kind of recv() error; errno is set, but we |
| 451 | ensure that the result buffer is empty before returning. */ |
| 452 | |
| 453 | *buffer = 0; |
| 454 | return -1; |
| 455 | } |
| 456 | |
| 457 | |
| 458 | |
| 459 | |
| 460 | |
| 461 | /************************************************* |
| 462 | * Read SMTP response * |
| 463 | *************************************************/ |
| 464 | |
| 465 | /* This function reads an SMTP response with a timeout, and returns the |
| 466 | response in the given buffer, as a string. A multiline response will contain |
| 467 | newline characters between the lines. The function also analyzes the first |
| 468 | digit of the reply code and returns FALSE if it is not acceptable. FALSE is |
| 469 | also returned after a reading error. In this case buffer[0] will be zero, and |
| 470 | the error code will be in errno. |
| 471 | |
| 472 | Arguments: |
| 473 | inblock the SMTP input block (contains holding buffer, socket, etc.) |
| 474 | buffer where to put the response |
| 475 | size the size of the buffer |
| 476 | okdigit the expected first digit of the response |
| 477 | timeout the timeout to use |
| 478 | |
| 479 | Returns: TRUE if a valid, non-error response was received; else FALSE |
| 480 | */ |
| 481 | |
| 482 | BOOL |
| 483 | smtp_read_response(smtp_inblock *inblock, uschar *buffer, int size, int okdigit, |
| 484 | int timeout) |
| 485 | { |
| 486 | uschar *ptr = buffer; |
| 487 | int count; |
| 488 | |
| 489 | errno = 0; /* Ensure errno starts out zero */ |
| 490 | |
| 491 | /* This is a loop to read and concatentate the lines that make up a multi-line |
| 492 | response. */ |
| 493 | |
| 494 | for (;;) |
| 495 | { |
| 496 | if ((count = read_response_line(inblock, ptr, size, timeout)) < 0) |
| 497 | return FALSE; |
| 498 | |
| 499 | HDEBUG(D_transport|D_acl|D_v) |
| 500 | debug_printf(" %s %s\n", (ptr == buffer)? "SMTP<<" : " ", ptr); |
| 501 | |
| 502 | /* Check the format of the response: it must start with three digits; if |
| 503 | these are followed by a space or end of line, the response is complete. If |
| 504 | they are followed by '-' this is a multi-line response and we must look for |
| 505 | another line until the final line is reached. The only use made of multi-line |
| 506 | responses is to pass them back as error messages. We therefore just |
| 507 | concatenate them all within the buffer, which should be large enough to |
| 508 | accept any reasonable number of lines. */ |
| 509 | |
| 510 | if (count < 3 || |
| 511 | !isdigit(ptr[0]) || |
| 512 | !isdigit(ptr[1]) || |
| 513 | !isdigit(ptr[2]) || |
| 514 | (ptr[3] != '-' && ptr[3] != ' ' && ptr[3] != 0)) |
| 515 | { |
| 516 | errno = ERRNO_SMTPFORMAT; /* format error */ |
| 517 | return FALSE; |
| 518 | } |
| 519 | |
| 520 | /* If the line we have just read is a terminal line, line, we are done. |
| 521 | Otherwise more data has to be read. */ |
| 522 | |
| 523 | if (ptr[3] != '-') break; |
| 524 | |
| 525 | /* Move the reading pointer upwards in the buffer and insert \n between the |
| 526 | components of a multiline response. Space is left for this by read_response_ |
| 527 | line(). */ |
| 528 | |
| 529 | ptr += count; |
| 530 | *ptr++ = '\n'; |
| 531 | size -= count + 1; |
| 532 | } |
| 533 | |
| 534 | /* Return a value that depends on the SMTP return code. On some systems a |
| 535 | non-zero value of errno has been seen at this point, so ensure it is zero, |
| 536 | because the caller of this function looks at errno when FALSE is returned, to |
| 537 | distinguish between an unexpected return code and other errors such as |
| 538 | timeouts, lost connections, etc. */ |
| 539 | |
| 540 | errno = 0; |
| 541 | return buffer[0] == okdigit; |
| 542 | } |
| 543 | |
| 544 | /* End of smtp_out.c */ |