1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2017 */
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 * 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)
178 fastopen non-null iff TCP_FASTOPEN can be used; may indicate early-data to
179 be sent in SYN segment
181 Returns: 0 on success; -1 on failure, with errno set
185 ip_connect(int sock, int af, const uschar *address, int port, int timeout,
186 const blob * fastopen)
188 struct sockaddr_in s_in4;
189 struct sockaddr *s_ptr;
190 int s_len, rc, save_errno;
192 /* For an IPv6 address, use an IPv6 sockaddr structure. */
195 struct sockaddr_in6 s_in6;
198 memset(&s_in6, 0, sizeof(s_in6));
199 ip_addrinfo(address, &s_in6); /* Panic-dies on error */
200 s_in6.sin6_port = htons(port);
201 s_ptr = (struct sockaddr *)&s_in6;
202 s_len = sizeof(s_in6);
205 #else /* HAVE_IPV6 */
206 af = af; /* Avoid compiler warning */
207 #endif /* HAVE_IPV6 */
209 /* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with
213 memset(&s_in4, 0, sizeof(s_in4));
214 s_in4.sin_family = AF_INET;
215 s_in4.sin_port = htons(port);
216 s_in4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CCS address);
217 s_ptr = (struct sockaddr *)&s_in4;
218 s_len = sizeof(s_in4);
221 /* If no connection timeout is set, just call connect() without setting a
222 timer, thereby allowing the inbuilt OS timeout to operate. */
224 callout_address = string_sprintf("[%s]:%d", address, port);
225 sigalrm_seen = FALSE;
226 if (timeout > 0) alarm(timeout);
228 #if defined(TCP_FASTOPEN) && defined(MSG_FASTOPEN)
229 /* TCP Fast Open, if the system has a cookie from a previous call to
230 this peer, can send data in the SYN packet. The peer can send data
231 before it gets our ACK of its SYN,ACK - the latter is useful for
232 the SMTP banner. Other (than SMTP) cases of TCP connections can
233 possibly use the data-on-syn, so support that too. */
237 if ((rc = sendto(sock, fastopen->data, fastopen->len,
238 MSG_FASTOPEN | MSG_DONTWAIT, s_ptr, s_len)) >= 0)
239 /* seen for with-data, experimental TFO option, with-cookie case */
241 DEBUG(D_transport|D_v) debug_printf("TFO mode connection attempt, %s data\n",
242 fastopen->len > 0 ? "with" : "no");
243 tcp_out_fastopen = fastopen->len > 0 ? 2 : 1;
245 else if (errno == EINPROGRESS) /* expected for nonready peer */
246 /* seen for no-data, proper TFO option, both cookie-request and with-cookie cases */
247 /* apparently no visibility of the diffference at this point */
248 /* with netwk delay, post-conn tcp_info sees unacked 1 for R, 2 for C; code in smtp_out.c */
249 /* ? older Experimental TFO option behaviour ? */
250 { /* queue unsent data */
253 tcp_out_fastopen = 1; /* we tried; unknown if useful yet */
256 else if ( (rc = send(sock, fastopen->data, fastopen->len, 0)) < 0
257 && errno == EINPROGRESS /* expected for nonready peer */
261 else if(errno == EOPNOTSUPP)
264 debug_printf("Tried TCP Fast Open but apparently not enabled by sysctl\n");
272 if ((rc = connect(sock, s_ptr, s_len)) >= 0)
273 if ( fastopen && fastopen->data && fastopen->len
274 && send(sock, fastopen->data, fastopen->len, 0) < 0)
281 /* There is a testing facility for simulating a connection timeout, as I
282 can't think of any other way of doing this. It converts a connection refused
283 into a timeout if the timeout is set to 999999. */
285 if (running_in_test_harness && save_errno == ECONNREFUSED && timeout == 999999)
297 /* A failure whose error code is "Interrupted system call" is in fact
298 an externally applied timeout if the signal handler has been run. */
300 errno = save_errno == EINTR && sigalrm_seen ? ETIMEDOUT : save_errno;
306 /*************************************************
307 * Create connected socket to remote host *
308 *************************************************/
310 /* Create a socket and connect to host (name or number, ipv6 ok)
311 at one of port-range.
314 type SOCK_DGRAM or SOCK_STREAM
315 af AF_INET6 or AF_INET for the socket type
316 address the remote address, in text form
317 portlo,porthi the remote port range
319 connhost if not NULL, host_item to be filled in with connection details
320 errstr pointer for allocated string on error
321 fastopen with SOCK_STREAM, if non-null, request TCP Fast Open.
322 Additionally, optional early-data to send
325 socket fd, or -1 on failure (having allocated an error string)
328 ip_connectedsocket(int type, const uschar * hostname, int portlo, int porthi,
329 int timeout, host_item * connhost, uschar ** errstr, const blob * fastopen)
334 int af = 0, fd, fd4 = -1, fd6 = -1;
337 shost.address = NULL;
341 namelen = Ustrlen(hostname);
343 /* Anything enclosed in [] must be an IP address. */
345 if (hostname[0] == '[' &&
346 hostname[namelen - 1] == ']')
348 uschar * host = string_copyn(hostname+1, namelen-2);
349 if (string_is_ip_address(host, NULL) == 0)
351 *errstr = string_sprintf("malformed IP address \"%s\"", hostname);
354 shost.name = shost.address = host;
357 /* Otherwise check for an unadorned IP address */
359 else if (string_is_ip_address(hostname, NULL) != 0)
360 shost.name = shost.address = string_copyn(hostname, namelen);
362 /* Otherwise lookup IP address(es) from the name */
366 shost.name = string_copyn(hostname, namelen);
367 if (host_find_byname(&shost, NULL, HOST_FIND_QUALIFY_SINGLE,
368 NULL, FALSE) != HOST_FOUND)
370 *errstr = string_sprintf("no IP address found for host %s", shost.name);
375 /* Try to connect to the server - test each IP till one works */
377 for (h = &shost; h; h = h->next)
379 fd = Ustrchr(h->address, ':') != 0
380 ? fd6 < 0 ? (fd6 = ip_socket(type, af = AF_INET6)) : fd6
381 : fd4 < 0 ? (fd4 = ip_socket(type, af = AF_INET )) : fd4;
385 *errstr = string_sprintf("failed to create socket: %s", strerror(errno));
389 for(port = portlo; port <= porthi; port++)
390 if (ip_connect(fd, af, h->address, port, timeout, fastopen) == 0)
392 if (fd != fd6) close(fd6);
393 if (fd != fd4) close(fd4);
398 connhost->next = NULL;
404 *errstr = string_sprintf("failed to connect to any address for %s: %s",
405 hostname, strerror(errno));
408 close(fd4); close(fd6); return -1;
414 ip_tcpsocket(const uschar * hostport, uschar ** errstr, int tmo)
417 uschar hostname[256];
418 unsigned int portlow, porthigh;
420 /* extract host and port part */
421 scan = sscanf(CS hostport, "%255s %u-%u", hostname, &portlow, &porthigh);
426 *errstr = string_sprintf("invalid socket '%s'", hostport);
432 return ip_connectedsocket(SOCK_STREAM, hostname, portlow, porthigh,
433 tmo, NULL, errstr, NULL);
437 ip_unixsocket(const uschar * path, uschar ** errstr)
440 struct sockaddr_un server;
442 if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
444 *errstr = US"can't open UNIX socket.";
448 callout_address = string_copy(path);
449 server.sun_family = AF_UNIX;
450 Ustrncpy(server.sun_path, path, sizeof(server.sun_path)-1);
451 server.sun_path[sizeof(server.sun_path)-1] = '\0';
452 if (connect(sock, (struct sockaddr *) &server, sizeof(server)) < 0)
456 *errstr = string_sprintf("unable to connect to UNIX socket (%s): %s",
457 path, strerror(err));
464 ip_streamsocket(const uschar * spec, uschar ** errstr, int tmo)
467 ? ip_unixsocket(spec, errstr) : ip_tcpsocket(spec, errstr, tmo);
470 /*************************************************
471 * Set keepalive on a socket *
472 *************************************************/
474 /* Can be called for both incoming and outgoing sockets.
478 address the remote host address, for failure logging
479 torf true for outgoing connection, false for incoming
485 ip_keepalive(int sock, const uschar *address, BOOL torf)
488 if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
489 US (&fodder), sizeof(fodder)) != 0)
490 log_write(0, LOG_MAIN, "setsockopt(SO_KEEPALIVE) on connection %s %s "
491 "failed: %s", torf? "to":"from", address, strerror(errno));
496 /*************************************************
497 * Receive from a socket with timeout *
498 *************************************************/
502 fd the file descriptor
503 timeout the timeout, seconds
504 Returns: TRUE => ready for i/o
505 FALSE => timed out, or other error
508 fd_ready(int fd, int timeout)
511 time_t start_recv = time(NULL);
512 int time_left = timeout;
520 /* Wait until the socket is ready */
524 struct timeval tv = { .tv_sec = time_left, .tv_usec = 0 };
525 FD_ZERO (&select_inset);
526 FD_SET (fd, &select_inset);
528 /*DEBUG(D_transport) debug_printf("waiting for data on fd\n");*/
529 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&select_inset, NULL, NULL, &tv);
531 /* If some interrupt arrived, just retry. We presume this to be rare,
532 but it can happen (e.g. the SIGUSR1 signal sent by exiwhat causes
535 Aug 2004: Somebody set up a cron job that ran exiwhat every 2 minutes, making
536 the interrupt not at all rare. Since the timeout is typically more than 2
537 minutes, the effect was to block the timeout completely. To prevent this
538 happening again, we do an explicit time test and adjust the timeout
541 if (rc < 0 && errno == EINTR)
543 DEBUG(D_transport) debug_printf("EINTR while waiting for socket data\n");
545 /* Watch out, 'continue' jumps to the condition, not to the loops top */
546 time_left = timeout - (time(NULL) - start_recv);
547 if (time_left > 0) continue;
556 /* Checking the FD_ISSET is not enough, if we're interrupted, the
557 select_inset may still contain the 'input'. */
559 while (rc < 0 || !FD_ISSET(fd, &select_inset));
563 /* The timeout is implemented using select(), and we loop to cover select()
564 getting interrupted, and the possibility of select() returning with a positive
565 result but no ready descriptor. Is this in fact possible?
570 bufsize the buffer size
573 Returns: > 0 => that much data read
574 <= 0 on error or EOF; errno set - zero for EOF
578 ip_recv(int sock, uschar *buffer, int buffsize, int timeout)
582 if (!fd_ready(sock, timeout))
585 /* The socket is ready, read from it (via TLS if it's active). On EOF (i.e.
586 close down of the connection), set errno to zero; otherwise leave it alone. */
589 if (tls_out.active == sock)
590 rc = tls_read(FALSE, buffer, buffsize);
591 else if (tls_in.active == sock)
592 rc = tls_read(TRUE, buffer, buffsize);
595 rc = recv(sock, buffer, buffsize, 0);
597 if (rc > 0) return rc;
598 if (rc == 0) errno = 0;
605 /*************************************************
606 * Lookup address family of potential socket *
607 *************************************************/
609 /* Given a file-descriptor, check to see if it's a socket and, if so,
610 return the address family; detects IPv4 vs IPv6. If not a socket then
613 The value 0 is typically AF_UNSPEC, which should not be seen on a connected
614 fd. If the return is -1, the errno will be from getsockname(); probably
615 ENOTSOCK or ECONNRESET.
617 Arguments: socket-or-not fd
618 Returns: address family or -1
622 ip_get_address_family(int fd)
624 struct sockaddr_storage ss;
625 socklen_t sslen = sizeof(ss);
627 if (getsockname(fd, (struct sockaddr *) &ss, &sslen) < 0)
630 return (int) ss.ss_family;
636 /*************************************************
637 * Lookup DSCP settings for a socket *
638 *************************************************/
640 struct dscp_name_tableentry {
644 /* Keep both of these tables sorted! */
645 static struct dscp_name_tableentry dscp_table[] = {
646 #ifdef IPTOS_DSCP_AF11
647 { CUS"af11", IPTOS_DSCP_AF11 },
648 { CUS"af12", IPTOS_DSCP_AF12 },
649 { CUS"af13", IPTOS_DSCP_AF13 },
650 { CUS"af21", IPTOS_DSCP_AF21 },
651 { CUS"af22", IPTOS_DSCP_AF22 },
652 { CUS"af23", IPTOS_DSCP_AF23 },
653 { CUS"af31", IPTOS_DSCP_AF31 },
654 { CUS"af32", IPTOS_DSCP_AF32 },
655 { CUS"af33", IPTOS_DSCP_AF33 },
656 { CUS"af41", IPTOS_DSCP_AF41 },
657 { CUS"af42", IPTOS_DSCP_AF42 },
658 { CUS"af43", IPTOS_DSCP_AF43 },
659 { CUS"ef", IPTOS_DSCP_EF },
662 { CUS"lowcost", IPTOS_LOWCOST },
664 { CUS"lowdelay", IPTOS_LOWDELAY },
666 { CUS"mincost", IPTOS_MINCOST },
668 { CUS"reliability", IPTOS_RELIABILITY },
669 { CUS"throughput", IPTOS_THROUGHPUT }
671 static int dscp_table_size =
672 sizeof(dscp_table) / sizeof(struct dscp_name_tableentry);
674 /* DSCP values change by protocol family, and so do the options used for
675 setsockopt(); this utility does all the lookups. It takes an unexpanded
676 option string, expands it, strips off affix whitespace, then checks if it's
677 a number. If all of what's left is a number, then that's how the option will
678 be parsed and success/failure is a range check. If it's not all a number,
679 then it must be a supported keyword.
682 dscp_name a string, so far unvalidated
683 af address_family in use
684 level setsockopt level to use
685 optname setsockopt name to use
686 dscp_value value for dscp_name
688 Returns: TRUE if okay to setsockopt(), else FALSE
690 *level and *optname may be set even if FALSE is returned
694 dscp_lookup(const uschar *dscp_name, int af,
695 int *level, int *optname, int *dscp_value)
697 uschar *dscp_lookup, *p;
706 #if HAVE_IPV6 && defined(IPV6_TCLASS)
707 else if (af == AF_INET6)
709 *level = IPPROTO_IPV6;
710 *optname = IPV6_TCLASS;
716 debug_printf("Unhandled address family %d in dscp_lookup()\n", af);
722 debug_printf("[empty DSCP]\n");
725 dscp_lookup = expand_string(US dscp_name);
726 if (dscp_lookup == NULL || *dscp_lookup == '\0')
729 p = dscp_lookup + Ustrlen(dscp_lookup) - 1;
730 while (isspace(*p)) *p-- = '\0';
731 while (isspace(*dscp_lookup) && dscp_lookup < p) dscp_lookup++;
732 if (*dscp_lookup == '\0')
735 rawlong = Ustrtol(dscp_lookup, &p, 0);
736 if (p != dscp_lookup && *p == '\0')
738 /* We have six bits available, which will end up shifted to fit in 0xFC mask.
739 RFC 2597 defines the values unshifted. */
740 if (rawlong < 0 || rawlong > 0x3F)
743 debug_printf("DSCP value %ld out of range, ignored.\n", rawlong);
746 *dscp_value = rawlong << 2;
751 last = dscp_table_size;
754 int middle = (first + last)/2;
755 int c = Ustrcmp(dscp_lookup, dscp_table[middle].name);
758 *dscp_value = dscp_table[middle].value;
770 dscp_list_to_stream(FILE *stream)
773 for (i=0; i < dscp_table_size; ++i)
774 fprintf(stream, "%s\n", dscp_table[i].name);