1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
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, especially 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 *************************************************/
166 #ifdef EXIM_TFO_PROBE
171 int sock, backlog = 5;
173 if ( (sock = socket(SOCK_STREAM, AF_INET, 0)) < 0
174 && setsockopt(sock, IPPROTO_TCP, TCP_FASTOPEN, &backlog, sizeof(backlog))
176 tcp_fastopen_ok = TRUE;
183 /*************************************************
184 * Connect socket to remote host *
185 *************************************************/
187 /* This function connects a socket to a remote address and port. The socket may
188 or may not have previously been bound to a local interface. The socket is not
189 closed, even in cases of error. It is expected that the calling function, which
190 created the socket, will be the one that closes it.
194 af AF_INET6 or AF_INET for the socket type
195 address the remote address, in text form
197 timeout a timeout (zero for indefinite timeout)
198 fastopen_blob non-null iff TCP_FASTOPEN can be used; may indicate early-data to
199 be sent in SYN segment
201 Returns: 0 on success; -1 on failure, with errno set
205 ip_connect(int sock, int af, const uschar *address, int port, int timeout,
206 const blob * fastopen_blob)
208 struct sockaddr_in s_in4;
209 struct sockaddr *s_ptr;
210 int s_len, rc, save_errno;
212 /* For an IPv6 address, use an IPv6 sockaddr structure. */
215 struct sockaddr_in6 s_in6;
218 memset(&s_in6, 0, sizeof(s_in6));
219 ip_addrinfo(address, &s_in6); /* Panic-dies on error */
220 s_in6.sin6_port = htons(port);
221 s_ptr = (struct sockaddr *)&s_in6;
222 s_len = sizeof(s_in6);
225 #else /* HAVE_IPV6 */
226 af = af; /* Avoid compiler warning */
227 #endif /* HAVE_IPV6 */
229 /* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with
233 memset(&s_in4, 0, sizeof(s_in4));
234 s_in4.sin_family = AF_INET;
235 s_in4.sin_port = htons(port);
236 s_in4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CCS address);
237 s_ptr = (struct sockaddr *)&s_in4;
238 s_len = sizeof(s_in4);
241 /* If no connection timeout is set, just call connect() without setting a
242 timer, thereby allowing the inbuilt OS timeout to operate. */
244 callout_address = string_sprintf("[%s]:%d", address, port);
245 sigalrm_seen = FALSE;
246 if (timeout > 0) alarm(timeout);
248 #if defined(TCP_FASTOPEN) && defined(MSG_FASTOPEN)
249 /* TCP Fast Open, if the system has a cookie from a previous call to
250 this peer, can send data in the SYN packet. The peer can send data
251 before it gets our ACK of its SYN,ACK - the latter is useful for
252 the SMTP banner. Other (than SMTP) cases of TCP connections can
253 possibly use the data-on-syn, so support that too.
255 This is a Linux implementation. It might be useable on FreeBSD; I have
256 not checked. I think MacOS has a "connectx" call for this purpose,
257 rather than using "sendto" ? */
259 if (fastopen_blob && tcp_fastopen_ok)
261 if ((rc = sendto(sock, fastopen_blob->data, fastopen_blob->len,
262 MSG_FASTOPEN | MSG_DONTWAIT, s_ptr, s_len)) >= 0)
263 /* seen for with-data, experimental TFO option, with-cookie case */
264 /* seen for with-data, proper TFO opt, with-cookie case */
266 DEBUG(D_transport|D_v)
267 debug_printf("non-TFO mode connection attempt to %s, %lu data\n",
268 address, (unsigned long)fastopen_blob->len);
269 /*XXX also seen on successful TFO, sigh */
270 tcp_out_fastopen = fastopen_blob->len > 0 ? 2 : 1;
272 else if (errno == EINPROGRESS) /* expected if we had no cookie for peer */
273 /* seen for no-data, proper TFO option, both cookie-request and with-cookie cases */
274 /* apparently no visibility of the diffference at this point */
275 /* seen for with-data, proper TFO opt, cookie-req */
276 /* with netwk delay, post-conn tcp_info sees unacked 1 for R, 2 for C; code in smtp_out.c */
277 /* ? older Experimental TFO option behaviour ? */
278 { /* queue unsent data */
279 DEBUG(D_transport|D_v) debug_printf("TFO mode sendto, %s data: EINPROGRESS\n",
280 fastopen_blob->len > 0 ? "with" : "no");
281 if (!fastopen_blob->data)
283 tcp_out_fastopen = 1; /* we tried; unknown if useful yet */
287 rc = send(sock, fastopen_blob->data, fastopen_blob->len, 0);
289 else if(errno == EOPNOTSUPP)
292 debug_printf("Tried TCP Fast Open but apparently not enabled by sysctl\n");
300 DEBUG(D_transport|D_v) if (fastopen_blob)
301 debug_printf("non-TFO mode connection attempt to %s, %lu data\n",
302 address, (unsigned long)fastopen_blob->len);
303 if ((rc = connect(sock, s_ptr, s_len)) >= 0)
304 if ( fastopen_blob && fastopen_blob->data && fastopen_blob->len
305 && send(sock, fastopen_blob->data, fastopen_blob->len, 0) < 0)
312 /* There is a testing facility for simulating a connection timeout, as I
313 can't think of any other way of doing this. It converts a connection refused
314 into a timeout if the timeout is set to 999999. */
316 if (running_in_test_harness && save_errno == ECONNREFUSED && timeout == 999999)
328 /* A failure whose error code is "Interrupted system call" is in fact
329 an externally applied timeout if the signal handler has been run. */
331 errno = save_errno == EINTR && sigalrm_seen ? ETIMEDOUT : save_errno;
337 /*************************************************
338 * Create connected socket to remote host *
339 *************************************************/
341 /* Create a socket and connect to host (name or number, ipv6 ok)
342 at one of port-range.
345 type SOCK_DGRAM or SOCK_STREAM
346 af AF_INET6 or AF_INET for the socket type
347 hostname host name, or ip address (as text)
348 portlo,porthi the remote port range
350 connhost if not NULL, host_item to be filled in with connection details
351 errstr pointer for allocated string on error
352 fastopen_blob with SOCK_STREAM, if non-null, request TCP Fast Open.
353 Additionally, optional early-data to send
356 socket fd, or -1 on failure (having allocated an error string)
359 ip_connectedsocket(int type, const uschar * hostname, int portlo, int porthi,
360 int timeout, host_item * connhost, uschar ** errstr, const blob * fastopen_blob)
365 int af = 0, fd, fd4 = -1, fd6 = -1;
368 shost.address = NULL;
372 namelen = Ustrlen(hostname);
374 /* Anything enclosed in [] must be an IP address. */
376 if (hostname[0] == '[' &&
377 hostname[namelen - 1] == ']')
379 uschar * host = string_copyn(hostname+1, namelen-2);
380 if (string_is_ip_address(host, NULL) == 0)
382 *errstr = string_sprintf("malformed IP address \"%s\"", hostname);
385 shost.name = shost.address = host;
388 /* Otherwise check for an unadorned IP address */
390 else if (string_is_ip_address(hostname, NULL) != 0)
391 shost.name = shost.address = string_copyn(hostname, namelen);
393 /* Otherwise lookup IP address(es) from the name */
397 shost.name = string_copyn(hostname, namelen);
398 if (host_find_byname(&shost, NULL, HOST_FIND_QUALIFY_SINGLE,
399 NULL, FALSE) != HOST_FOUND)
401 *errstr = string_sprintf("no IP address found for host %s", shost.name);
406 /* Try to connect to the server - test each IP till one works */
408 for (h = &shost; h; h = h->next)
410 fd = Ustrchr(h->address, ':') != 0
411 ? fd6 < 0 ? (fd6 = ip_socket(type, af = AF_INET6)) : fd6
412 : fd4 < 0 ? (fd4 = ip_socket(type, af = AF_INET )) : fd4;
416 *errstr = string_sprintf("failed to create socket: %s", strerror(errno));
420 for(port = portlo; port <= porthi; port++)
421 if (ip_connect(fd, af, h->address, port, timeout, fastopen_blob) == 0)
423 if (fd != fd6) close(fd6);
424 if (fd != fd4) close(fd4);
429 connhost->next = NULL;
435 *errstr = string_sprintf("failed to connect to any address for %s: %s",
436 hostname, strerror(errno));
439 close(fd4); close(fd6); return -1;
445 ip_tcpsocket(const uschar * hostport, uschar ** errstr, int tmo)
448 uschar hostname[256];
449 unsigned int portlow, porthigh;
451 /* extract host and port part */
452 scan = sscanf(CS hostport, "%255s %u-%u", hostname, &portlow, &porthigh);
457 *errstr = string_sprintf("invalid socket '%s'", hostport);
463 return ip_connectedsocket(SOCK_STREAM, hostname, portlow, porthigh,
464 tmo, NULL, errstr, NULL);
468 ip_unixsocket(const uschar * path, uschar ** errstr)
471 struct sockaddr_un server;
473 if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
475 *errstr = US"can't open UNIX socket.";
479 callout_address = string_copy(path);
480 server.sun_family = AF_UNIX;
481 Ustrncpy(server.sun_path, path, sizeof(server.sun_path)-1);
482 server.sun_path[sizeof(server.sun_path)-1] = '\0';
483 if (connect(sock, (struct sockaddr *) &server, sizeof(server)) < 0)
487 *errstr = string_sprintf("unable to connect to UNIX socket (%s): %s",
488 path, strerror(err));
495 ip_streamsocket(const uschar * spec, uschar ** errstr, int tmo)
498 ? ip_unixsocket(spec, errstr) : ip_tcpsocket(spec, errstr, tmo);
501 /*************************************************
502 * Set keepalive on a socket *
503 *************************************************/
505 /* Can be called for both incoming and outgoing sockets.
509 address the remote host address, for failure logging
510 torf true for outgoing connection, false for incoming
516 ip_keepalive(int sock, const uschar *address, BOOL torf)
519 if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
520 US (&fodder), sizeof(fodder)) != 0)
521 log_write(0, LOG_MAIN, "setsockopt(SO_KEEPALIVE) on connection %s %s "
522 "failed: %s", torf? "to":"from", address, strerror(errno));
527 /*************************************************
528 * Receive from a socket with timeout *
529 *************************************************/
533 fd the file descriptor
534 timeout the timeout, seconds
535 Returns: TRUE => ready for i/o
536 FALSE => timed out, or other error
539 fd_ready(int fd, int timeout)
542 time_t start_recv = time(NULL);
543 int time_left = timeout;
551 /* Wait until the socket is ready */
555 struct timeval tv = { .tv_sec = time_left, .tv_usec = 0 };
556 FD_ZERO (&select_inset);
557 FD_SET (fd, &select_inset);
559 /*DEBUG(D_transport) debug_printf("waiting for data on fd\n");*/
560 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&select_inset, NULL, NULL, &tv);
562 /* If some interrupt arrived, just retry. We presume this to be rare,
563 but it can happen (e.g. the SIGUSR1 signal sent by exiwhat causes
566 Aug 2004: Somebody set up a cron job that ran exiwhat every 2 minutes, making
567 the interrupt not at all rare. Since the timeout is typically more than 2
568 minutes, the effect was to block the timeout completely. To prevent this
569 happening again, we do an explicit time test and adjust the timeout
572 if (rc < 0 && errno == EINTR)
574 DEBUG(D_transport) debug_printf("EINTR while waiting for socket data\n");
576 /* Watch out, 'continue' jumps to the condition, not to the loops top */
577 time_left = timeout - (time(NULL) - start_recv);
578 if (time_left > 0) continue;
587 /* Checking the FD_ISSET is not enough, if we're interrupted, the
588 select_inset may still contain the 'input'. */
590 while (rc < 0 || !FD_ISSET(fd, &select_inset));
594 /* The timeout is implemented using select(), and we loop to cover select()
595 getting interrupted, and the possibility of select() returning with a positive
596 result but no ready descriptor. Is this in fact possible?
599 cctx the connection context (socket fd, possibly TLS context)
601 bufsize the buffer size
604 Returns: > 0 => that much data read
605 <= 0 on error or EOF; errno set - zero for EOF
609 ip_recv(client_conn_ctx * cctx, uschar * buffer, int buffsize, int timeout)
613 if (!fd_ready(cctx->sock, timeout))
616 /* The socket is ready, read from it (via TLS if it's active). On EOF (i.e.
617 close down of the connection), set errno to zero; otherwise leave it alone. */
620 if (cctx->tls_ctx) /* client TLS */
621 rc = tls_read(cctx->tls_ctx, buffer, buffsize);
622 else if (tls_in.active.sock == cctx->sock) /* server TLS */
623 rc = tls_read(NULL, buffer, buffsize);
626 rc = recv(cctx->sock, buffer, buffsize, 0);
628 if (rc > 0) return rc;
629 if (rc == 0) errno = 0;
636 /*************************************************
637 * Lookup address family of potential socket *
638 *************************************************/
640 /* Given a file-descriptor, check to see if it's a socket and, if so,
641 return the address family; detects IPv4 vs IPv6. If not a socket then
644 The value 0 is typically AF_UNSPEC, which should not be seen on a connected
645 fd. If the return is -1, the errno will be from getsockname(); probably
646 ENOTSOCK or ECONNRESET.
648 Arguments: socket-or-not fd
649 Returns: address family or -1
653 ip_get_address_family(int fd)
655 struct sockaddr_storage ss;
656 socklen_t sslen = sizeof(ss);
658 if (getsockname(fd, (struct sockaddr *) &ss, &sslen) < 0)
661 return (int) ss.ss_family;
667 /*************************************************
668 * Lookup DSCP settings for a socket *
669 *************************************************/
671 struct dscp_name_tableentry {
675 /* Keep both of these tables sorted! */
676 static struct dscp_name_tableentry dscp_table[] = {
677 #ifdef IPTOS_DSCP_AF11
678 { CUS"af11", IPTOS_DSCP_AF11 },
679 { CUS"af12", IPTOS_DSCP_AF12 },
680 { CUS"af13", IPTOS_DSCP_AF13 },
681 { CUS"af21", IPTOS_DSCP_AF21 },
682 { CUS"af22", IPTOS_DSCP_AF22 },
683 { CUS"af23", IPTOS_DSCP_AF23 },
684 { CUS"af31", IPTOS_DSCP_AF31 },
685 { CUS"af32", IPTOS_DSCP_AF32 },
686 { CUS"af33", IPTOS_DSCP_AF33 },
687 { CUS"af41", IPTOS_DSCP_AF41 },
688 { CUS"af42", IPTOS_DSCP_AF42 },
689 { CUS"af43", IPTOS_DSCP_AF43 },
690 { CUS"ef", IPTOS_DSCP_EF },
693 { CUS"lowcost", IPTOS_LOWCOST },
695 { CUS"lowdelay", IPTOS_LOWDELAY },
697 { CUS"mincost", IPTOS_MINCOST },
699 { CUS"reliability", IPTOS_RELIABILITY },
700 { CUS"throughput", IPTOS_THROUGHPUT }
702 static int dscp_table_size =
703 sizeof(dscp_table) / sizeof(struct dscp_name_tableentry);
705 /* DSCP values change by protocol family, and so do the options used for
706 setsockopt(); this utility does all the lookups. It takes an unexpanded
707 option string, expands it, strips off affix whitespace, then checks if it's
708 a number. If all of what's left is a number, then that's how the option will
709 be parsed and success/failure is a range check. If it's not all a number,
710 then it must be a supported keyword.
713 dscp_name a string, so far unvalidated
714 af address_family in use
715 level setsockopt level to use
716 optname setsockopt name to use
717 dscp_value value for dscp_name
719 Returns: TRUE if okay to setsockopt(), else FALSE
721 *level and *optname may be set even if FALSE is returned
725 dscp_lookup(const uschar *dscp_name, int af,
726 int *level, int *optname, int *dscp_value)
728 uschar *dscp_lookup, *p;
737 #if HAVE_IPV6 && defined(IPV6_TCLASS)
738 else if (af == AF_INET6)
740 *level = IPPROTO_IPV6;
741 *optname = IPV6_TCLASS;
747 debug_printf("Unhandled address family %d in dscp_lookup()\n", af);
753 debug_printf("[empty DSCP]\n");
756 dscp_lookup = expand_string(US dscp_name);
757 if (dscp_lookup == NULL || *dscp_lookup == '\0')
760 p = dscp_lookup + Ustrlen(dscp_lookup) - 1;
761 while (isspace(*p)) *p-- = '\0';
762 while (isspace(*dscp_lookup) && dscp_lookup < p) dscp_lookup++;
763 if (*dscp_lookup == '\0')
766 rawlong = Ustrtol(dscp_lookup, &p, 0);
767 if (p != dscp_lookup && *p == '\0')
769 /* We have six bits available, which will end up shifted to fit in 0xFC mask.
770 RFC 2597 defines the values unshifted. */
771 if (rawlong < 0 || rawlong > 0x3F)
774 debug_printf("DSCP value %ld out of range, ignored.\n", rawlong);
777 *dscp_value = rawlong << 2;
782 last = dscp_table_size;
785 int middle = (first + last)/2;
786 int c = Ustrcmp(dscp_lookup, dscp_table[middle].name);
789 *dscp_value = dscp_table[middle].value;
801 dscp_list_to_stream(FILE *stream)
804 for (i=0; i < dscp_table_size; ++i)
805 fprintf(stream, "%s\n", dscp_table[i].name);