1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Functions for doing things with sockets. With the advent of IPv6 this has
9 got messier, so that it's worth pulling out the code into separate functions
10 that other parts of Exim can call, expecially as there are now several
11 different places in the code where sockets are used. */
17 /*************************************************
19 *************************************************/
21 /* Socket creation happens in a number of places so it's packaged here for
25 type SOCK_DGRAM or SOCK_STREAM
26 af AF_INET or AF_INET6
28 Returns: socket number or -1 on failure
32 ip_socket(int type, int af)
34 int sock = socket(af, type, 0);
36 log_write(0, LOG_MAIN, "IPv%c socket creation failed: %s",
37 (af == AF_INET6)? '6':'4', strerror(errno));
45 /*************************************************
46 * Convert printing address to numeric *
47 *************************************************/
49 /* This function converts the textual form of an IP address into a numeric form
50 in an appropriate structure in an IPv6 environment. The getaddrinfo() function
51 can (apparently) handle more complicated addresses (e.g. those containing
52 scopes) than inet_pton() in some environments. We use hints to tell it that the
53 input must be a numeric address.
55 However, apparently some operating systems (or libraries) don't support
56 getaddrinfo(), so there is a build-time option to revert to inet_pton() (which
57 does not support scopes).
60 address textual form of the address
61 addr where to copy back the answer
63 Returns: nothing - failure provokes a panic-die
67 ip_addrinfo(const uschar *address, struct sockaddr_in6 *saddr)
69 #ifdef IPV6_USE_INET_PTON
71 if (inet_pton(AF_INET6, CCS address, &saddr->sin6_addr) != 1)
72 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
73 "IP address", address);
74 saddr->sin6_family = AF_INET6;
79 struct addrinfo hints, *res;
80 memset(&hints, 0, sizeof(hints));
81 hints.ai_family = AF_INET6;
82 hints.ai_socktype = SOCK_STREAM;
83 hints.ai_flags = AI_NUMERICHOST;
84 if ((rc = getaddrinfo(CCS address, NULL, &hints, &res)) != 0 || res == NULL)
85 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
86 "IP address: %s", address,
87 (rc == 0)? "NULL result returned" : gai_strerror(rc));
88 memcpy(saddr, res->ai_addr, res->ai_addrlen);
93 #endif /* HAVE_IPV6 */
96 /*************************************************
97 * Bind socket to interface and port *
98 *************************************************/
101 ip_addr(void * sin_, int af, const uschar * address, int port)
103 union sockaddr_46 * sin = sin_;
104 memset(sin, 0, sizeof(*sin));
106 /* Setup code when using an IPv6 socket. The wildcard address is ":", to
107 ensure an IPv6 socket is used. */
112 if (address[0] == ':' && address[1] == 0)
114 sin->v6.sin6_family = AF_INET6;
115 sin->v6.sin6_addr = in6addr_any;
118 ip_addrinfo(address, &sin->v6); /* Panic-dies on error */
119 sin->v6.sin6_port = htons(port);
120 return sizeof(sin->v6);
123 #else /* HAVE_IPv6 */
124 af = af; /* Avoid compiler warning */
125 #endif /* HAVE_IPV6 */
127 /* Setup code when using IPv4 socket. The wildcard address is "". */
130 sin->v4.sin_family = AF_INET;
131 sin->v4.sin_port = htons(port);
132 sin->v4.sin_addr.s_addr = address[0] == 0
133 ? (S_ADDR_TYPE)INADDR_ANY
134 : (S_ADDR_TYPE)inet_addr(CS address);
135 return sizeof(sin->v4);
141 /* This function binds a socket to a local interface address and port. For a
142 wildcard IPv6 bind, the address is ":".
146 af AF_INET or AF_INET6 - the socket type
147 address the IP address, in text form
148 port the IP port (host order)
150 Returns: the result of bind()
154 ip_bind(int sock, int af, uschar *address, int port)
156 union sockaddr_46 sin;
157 int s_len = ip_addr(&sin, af, address, port);
158 return bind(sock, (struct sockaddr *)&sin, s_len);
163 /*************************************************
164 * Connect socket to remote host *
165 *************************************************/
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. The socket is not
169 closed, even in cases of error. It is expected that the calling function, which
170 created the socket, will be the one that closes it.
174 af AF_INET6 or AF_INET for the socket type
175 address the remote address, in text form
177 timeout a timeout (zero for indefinite timeout)
179 Returns: 0 on success; -1 on failure, with errno set
183 ip_connect(int sock, int af, const uschar *address, int port, int timeout)
185 struct sockaddr_in s_in4;
186 struct sockaddr *s_ptr;
187 int s_len, rc, save_errno;
189 /* For an IPv6 address, use an IPv6 sockaddr structure. */
192 struct sockaddr_in6 s_in6;
195 memset(&s_in6, 0, sizeof(s_in6));
196 ip_addrinfo(address, &s_in6); /* Panic-dies on error */
197 s_in6.sin6_port = htons(port);
198 s_ptr = (struct sockaddr *)&s_in6;
199 s_len = sizeof(s_in6);
202 #else /* HAVE_IPV6 */
203 af = af; /* Avoid compiler warning */
204 #endif /* HAVE_IPV6 */
206 /* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with
210 memset(&s_in4, 0, sizeof(s_in4));
211 s_in4.sin_family = AF_INET;
212 s_in4.sin_port = htons(port);
213 s_in4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CCS address);
214 s_ptr = (struct sockaddr *)&s_in4;
215 s_len = sizeof(s_in4);
218 /* If no connection timeout is set, just call connect() without setting a
219 timer, thereby allowing the inbuilt OS timeout to operate. */
221 sigalrm_seen = FALSE;
222 if (timeout > 0) alarm(timeout);
223 rc = connect(sock, s_ptr, s_len);
227 /* There is a testing facility for simulating a connection timeout, as I
228 can't think of any other way of doing this. It converts a connection refused
229 into a timeout if the timeout is set to 999999. */
231 if (running_in_test_harness && save_errno == ECONNREFUSED && timeout == 999999)
242 callout_address = string_sprintf("[%s]:%d", address, port);
246 /* A failure whose error code is "Interrupted system call" is in fact
247 an externally applied timeout if the signal handler has been run. */
249 errno = save_errno == EINTR && sigalrm_seen ? ETIMEDOUT : save_errno;
255 /*************************************************
256 * Create connected socket to remote host *
257 *************************************************/
259 /* Create a socket and connect to host (name or number, ipv6 ok)
260 at one of port-range.
263 type SOCK_DGRAM or SOCK_STREAM
264 af AF_INET6 or AF_INET for the socket type
265 address the remote address, in text form
266 portlo,porthi the remote port range
268 connhost if not NULL, host_item filled in with connection details
269 errstr pointer for allocated string on error
272 socket fd, or -1 on failure (having allocated an error string)
275 ip_connectedsocket(int type, const uschar * hostname, int portlo, int porthi,
276 int timeout, host_item * connhost, uschar ** errstr)
281 int af = 0, fd, fd4 = -1, fd6 = -1;
284 shost.address = NULL;
288 namelen = Ustrlen(hostname);
290 /* Anything enclosed in [] must be an IP address. */
292 if (hostname[0] == '[' &&
293 hostname[namelen - 1] == ']')
295 uschar * host = string_copy(hostname);
296 host[namelen - 1] = 0;
298 if (string_is_ip_address(host, NULL) == 0)
300 *errstr = string_sprintf("malformed IP address \"%s\"", hostname);
303 shost.name = shost.address = host;
306 /* Otherwise check for an unadorned IP address */
308 else if (string_is_ip_address(hostname, NULL) != 0)
309 shost.name = shost.address = string_copy(hostname);
311 /* Otherwise lookup IP address(es) from the name */
315 shost.name = string_copy(hostname);
316 if (host_find_byname(&shost, NULL, HOST_FIND_QUALIFY_SINGLE,
317 NULL, FALSE) != HOST_FOUND)
319 *errstr = string_sprintf("no IP address found for host %s", shost.name);
324 /* Try to connect to the server - test each IP till one works */
326 for (h = &shost; h != NULL; h = h->next)
328 fd = (Ustrchr(h->address, ':') != 0)
329 ? (fd6 < 0) ? (fd6 = ip_socket(type, af = AF_INET6)) : fd6
330 : (fd4 < 0) ? (fd4 = ip_socket(type, af = AF_INET )) : fd4;
334 *errstr = string_sprintf("failed to create socket: %s", strerror(errno));
338 for(port = portlo; port <= porthi; port++)
339 if (ip_connect(fd, af, h->address, port, timeout) == 0)
341 if (fd != fd6) close(fd6);
342 if (fd != fd4) close(fd4);
347 connhost->next = NULL;
353 *errstr = string_sprintf("failed to connect to any address for %s: %s",
354 hostname, strerror(errno));
357 close(fd4); close(fd6); return -1;
362 ip_tcpsocket(const uschar * hostport, uschar ** errstr, int tmo)
365 uschar hostname[256];
366 unsigned int portlow, porthigh;
368 /* extract host and port part */
369 scan = sscanf(CS hostport, "%255s %u-%u", hostname, &portlow, &porthigh);
374 *errstr = string_sprintf("invalid socket '%s'", hostport);
380 return ip_connectedsocket(SOCK_STREAM, hostname, portlow, porthigh,
385 ip_unixsocket(const uschar * path, uschar ** errstr)
388 struct sockaddr_un server;
390 if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
392 *errstr = US"can't open UNIX socket.";
396 server.sun_family = AF_UNIX;
397 Ustrncpy(server.sun_path, path, sizeof(server.sun_path)-1);
398 server.sun_path[sizeof(server.sun_path)-1] = '\0';
399 if (connect(sock, (struct sockaddr *) &server, sizeof(server)) < 0)
403 *errstr = string_sprintf("unable to connect to UNIX socket (%s): %s",
404 path, strerror(err));
407 callout_address = string_copy(path);
412 ip_streamsocket(const uschar * spec, uschar ** errstr, int tmo)
415 ? ip_unixsocket(spec, errstr) : ip_tcpsocket(spec, errstr, tmo);
418 /*************************************************
419 * Set keepalive on a socket *
420 *************************************************/
422 /* Can be called for both incoming and outgoing sockets.
426 address the remote host address, for failure logging
427 torf true for outgoing connection, false for incoming
433 ip_keepalive(int sock, const uschar *address, BOOL torf)
436 if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
437 (uschar *)(&fodder), sizeof(fodder)) != 0)
438 log_write(0, LOG_MAIN, "setsockopt(SO_KEEPALIVE) on connection %s %s "
439 "failed: %s", torf? "to":"from", address, strerror(errno));
444 /*************************************************
445 * Receive from a socket with timeout *
446 *************************************************/
450 fd the file descriptor
451 timeout the timeout, seconds
452 Returns: TRUE => ready for i/o
453 FALSE => timed out, or other error
456 fd_ready(int fd, int timeout)
459 time_t start_recv = time(NULL);
460 int time_left = timeout;
468 /* Wait until the socket is ready */
472 struct timeval tv = { time_left, 0 };
473 FD_ZERO (&select_inset);
474 FD_SET (fd, &select_inset);
476 /*DEBUG(D_transport) debug_printf("waiting for data on fd\n");*/
477 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&select_inset, NULL, NULL, &tv);
479 /* If some interrupt arrived, just retry. We presume this to be rare,
480 but it can happen (e.g. the SIGUSR1 signal sent by exiwhat causes
483 Aug 2004: Somebody set up a cron job that ran exiwhat every 2 minutes, making
484 the interrupt not at all rare. Since the timeout is typically more than 2
485 minutes, the effect was to block the timeout completely. To prevent this
486 happening again, we do an explicit time test and adjust the timeout
489 if (rc < 0 && errno == EINTR)
491 DEBUG(D_transport) debug_printf("EINTR while waiting for socket data\n");
493 /* Watch out, 'continue' jumps to the condition, not to the loops top */
494 time_left = timeout - (time(NULL) - start_recv);
495 if (time_left > 0) continue;
504 /* Checking the FD_ISSET is not enough, if we're interrupted, the
505 select_inset may still contain the 'input'. */
507 while (rc < 0 || !FD_ISSET(fd, &select_inset));
511 /* The timeout is implemented using select(), and we loop to cover select()
512 getting interrupted, and the possibility of select() returning with a positive
513 result but no ready descriptor. Is this in fact possible?
518 bufsize the buffer size
521 Returns: > 0 => that much data read
522 <= 0 on error or EOF; errno set - zero for EOF
526 ip_recv(int sock, uschar *buffer, int buffsize, int timeout)
530 if (!fd_ready(sock, timeout))
533 /* The socket is ready, read from it (via TLS if it's active). On EOF (i.e.
534 close down of the connection), set errno to zero; otherwise leave it alone. */
537 if (tls_out.active == sock)
538 rc = tls_read(FALSE, buffer, buffsize);
539 else if (tls_in.active == sock)
540 rc = tls_read(TRUE, buffer, buffsize);
543 rc = recv(sock, buffer, buffsize, 0);
545 if (rc > 0) return rc;
546 if (rc == 0) errno = 0;
553 /*************************************************
554 * Lookup address family of potential socket *
555 *************************************************/
557 /* Given a file-descriptor, check to see if it's a socket and, if so,
558 return the address family; detects IPv4 vs IPv6. If not a socket then
561 The value 0 is typically AF_UNSPEC, which should not be seen on a connected
562 fd. If the return is -1, the errno will be from getsockname(); probably
563 ENOTSOCK or ECONNRESET.
565 Arguments: socket-or-not fd
566 Returns: address family or -1
570 ip_get_address_family(int fd)
572 struct sockaddr_storage ss;
573 socklen_t sslen = sizeof(ss);
575 if (getsockname(fd, (struct sockaddr *) &ss, &sslen) < 0)
578 return (int) ss.ss_family;
584 /*************************************************
585 * Lookup DSCP settings for a socket *
586 *************************************************/
588 struct dscp_name_tableentry {
592 /* Keep both of these tables sorted! */
593 static struct dscp_name_tableentry dscp_table[] = {
594 #ifdef IPTOS_DSCP_AF11
595 { CUS"af11", IPTOS_DSCP_AF11 },
596 { CUS"af12", IPTOS_DSCP_AF12 },
597 { CUS"af13", IPTOS_DSCP_AF13 },
598 { CUS"af21", IPTOS_DSCP_AF21 },
599 { CUS"af22", IPTOS_DSCP_AF22 },
600 { CUS"af23", IPTOS_DSCP_AF23 },
601 { CUS"af31", IPTOS_DSCP_AF31 },
602 { CUS"af32", IPTOS_DSCP_AF32 },
603 { CUS"af33", IPTOS_DSCP_AF33 },
604 { CUS"af41", IPTOS_DSCP_AF41 },
605 { CUS"af42", IPTOS_DSCP_AF42 },
606 { CUS"af43", IPTOS_DSCP_AF43 },
607 { CUS"ef", IPTOS_DSCP_EF },
610 { CUS"lowcost", IPTOS_LOWCOST },
612 { CUS"lowdelay", IPTOS_LOWDELAY },
614 { CUS"mincost", IPTOS_MINCOST },
616 { CUS"reliability", IPTOS_RELIABILITY },
617 { CUS"throughput", IPTOS_THROUGHPUT }
619 static int dscp_table_size =
620 sizeof(dscp_table) / sizeof(struct dscp_name_tableentry);
622 /* DSCP values change by protocol family, and so do the options used for
623 setsockopt(); this utility does all the lookups. It takes an unexpanded
624 option string, expands it, strips off affix whitespace, then checks if it's
625 a number. If all of what's left is a number, then that's how the option will
626 be parsed and success/failure is a range check. If it's not all a number,
627 then it must be a supported keyword.
630 dscp_name a string, so far unvalidated
631 af address_family in use
632 level setsockopt level to use
633 optname setsockopt name to use
634 dscp_value value for dscp_name
636 Returns: TRUE if okay to setsockopt(), else FALSE
638 *level and *optname may be set even if FALSE is returned
642 dscp_lookup(const uschar *dscp_name, int af,
643 int *level, int *optname, int *dscp_value)
645 uschar *dscp_lookup, *p;
654 #if HAVE_IPV6 && defined(IPV6_TCLASS)
655 else if (af == AF_INET6)
657 *level = IPPROTO_IPV6;
658 *optname = IPV6_TCLASS;
664 debug_printf("Unhandled address family %d in dscp_lookup()\n", af);
670 debug_printf("[empty DSCP]\n");
673 dscp_lookup = expand_string(US dscp_name);
674 if (dscp_lookup == NULL || *dscp_lookup == '\0')
677 p = dscp_lookup + Ustrlen(dscp_lookup) - 1;
678 while (isspace(*p)) *p-- = '\0';
679 while (isspace(*dscp_lookup) && dscp_lookup < p) dscp_lookup++;
680 if (*dscp_lookup == '\0')
683 rawlong = Ustrtol(dscp_lookup, &p, 0);
684 if (p != dscp_lookup && *p == '\0')
686 /* We have six bits available, which will end up shifted to fit in 0xFC mask.
687 RFC 2597 defines the values unshifted. */
688 if (rawlong < 0 || rawlong > 0x3F)
691 debug_printf("DSCP value %ld out of range, ignored.\n", rawlong);
694 *dscp_value = rawlong << 2;
699 last = dscp_table_size;
702 int middle = (first + last)/2;
703 int c = Ustrcmp(dscp_lookup, dscp_table[middle].name);
706 *dscp_value = dscp_table[middle].value;
718 dscp_list_to_stream(FILE *stream)
721 for (i=0; i < dscp_table_size; ++i)
722 fprintf(stream, "%s\n", dscp_table[i].name);