/************************************************* * Exim - an Internet mail transport agent * *************************************************/ /* Copyright (c) University of Cambridge 1995 - 2018 */ /* See the file NOTICE for conditions of use and distribution. */ /* Functions for doing things with sockets. With the advent of IPv6 this has got messier, so that it's worth pulling out the code into separate functions that other parts of Exim can call, especially as there are now several different places in the code where sockets are used. */ #include "exim.h" #if defined(TCP_FASTOPEN) # if defined(MSG_FASTOPEN) || defined(EXIM_TFO_CONNECTX) || defined(EXIM_TFO_FREEBSD) # define EXIM_SUPPORT_TFO # endif #endif /************************************************* * Create a socket * *************************************************/ /* Socket creation happens in a number of places so it's packaged here for convenience. Arguments: type SOCK_DGRAM or SOCK_STREAM af AF_INET or AF_INET6 Returns: socket number or -1 on failure */ int ip_socket(int type, int af) { int sock = socket(af, type, 0); if (sock < 0) log_write(0, LOG_MAIN, "IPv%c socket creation failed: %s", (af == AF_INET6)? '6':'4', strerror(errno)); return sock; } #if HAVE_IPV6 /************************************************* * Convert printing address to numeric * *************************************************/ /* This function converts the textual form of an IP address into a numeric form in an appropriate structure in an IPv6 environment. The getaddrinfo() function can (apparently) handle more complicated addresses (e.g. those containing scopes) than inet_pton() in some environments. We use hints to tell it that the input must be a numeric address. However, apparently some operating systems (or libraries) don't support getaddrinfo(), so there is a build-time option to revert to inet_pton() (which does not support scopes). Arguments: address textual form of the address addr where to copy back the answer Returns: nothing - failure provokes a panic-die */ static void ip_addrinfo(const uschar *address, struct sockaddr_in6 *saddr) { #ifdef IPV6_USE_INET_PTON if (inet_pton(AF_INET6, CCS address, &saddr->sin6_addr) != 1) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an " "IP address", address); saddr->sin6_family = AF_INET6; #else int rc; struct addrinfo hints, *res; memset(&hints, 0, sizeof(hints)); hints.ai_family = AF_INET6; hints.ai_socktype = SOCK_STREAM; hints.ai_flags = AI_NUMERICHOST; if ((rc = getaddrinfo(CCS address, NULL, &hints, &res)) != 0 || res == NULL) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an " "IP address: %s", address, (rc == 0)? "NULL result returned" : gai_strerror(rc)); memcpy(saddr, res->ai_addr, res->ai_addrlen); freeaddrinfo(res); #endif } #endif /* HAVE_IPV6 */ /************************************************* * Bind socket to interface and port * *************************************************/ int ip_addr(void * sin_, int af, const uschar * address, int port) { union sockaddr_46 * sin = sin_; memset(sin, 0, sizeof(*sin)); /* Setup code when using an IPv6 socket. The wildcard address is ":", to ensure an IPv6 socket is used. */ #if HAVE_IPV6 if (af == AF_INET6) { if (address[0] == ':' && address[1] == 0) { sin->v6.sin6_family = AF_INET6; sin->v6.sin6_addr = in6addr_any; } else ip_addrinfo(address, &sin->v6); /* Panic-dies on error */ sin->v6.sin6_port = htons(port); return sizeof(sin->v6); } else #else /* HAVE_IPv6 */ af = af; /* Avoid compiler warning */ #endif /* HAVE_IPV6 */ /* Setup code when using IPv4 socket. The wildcard address is "". */ { sin->v4.sin_family = AF_INET; sin->v4.sin_port = htons(port); sin->v4.sin_addr.s_addr = address[0] == 0 ? (S_ADDR_TYPE)INADDR_ANY : (S_ADDR_TYPE)inet_addr(CS address); return sizeof(sin->v4); } } /* This function binds a socket to a local interface address and port. For a wildcard IPv6 bind, the address is ":". Arguments: sock the socket af AF_INET or AF_INET6 - the socket type address the IP address, in text form port the IP port (host order) Returns: the result of bind() */ int ip_bind(int sock, int af, uschar *address, int port) { union sockaddr_46 sin; int s_len = ip_addr(&sin, af, address, port); return bind(sock, (struct sockaddr *)&sin, s_len); } /************************************************* * Connect socket to remote host * *************************************************/ /* This function connects a socket to a remote address and port. The socket may or may not have previously been bound to a local interface. The socket is not closed, even in cases of error. It is expected that the calling function, which created the socket, will be the one that closes it. Arguments: sock the socket af AF_INET6 or AF_INET for the socket type address the remote address, in text form port the remote port timeout a timeout (zero for indefinite timeout) fastopen_blob non-null iff TCP_FASTOPEN can be used; may indicate early-data to be sent in SYN segment. Any such data must be idempotent. Returns: 0 on success; -1 on failure, with errno set */ int ip_connect(int sock, int af, const uschar *address, int port, int timeout, const blob * fastopen_blob) { struct sockaddr_in s_in4; struct sockaddr *s_ptr; int s_len, rc, save_errno; /* For an IPv6 address, use an IPv6 sockaddr structure. */ #if HAVE_IPV6 struct sockaddr_in6 s_in6; if (af == AF_INET6) { memset(&s_in6, 0, sizeof(s_in6)); ip_addrinfo(address, &s_in6); /* Panic-dies on error */ s_in6.sin6_port = htons(port); s_ptr = (struct sockaddr *)&s_in6; s_len = sizeof(s_in6); } else #else /* HAVE_IPV6 */ af = af; /* Avoid compiler warning */ #endif /* HAVE_IPV6 */ /* For an IPv4 address, use an IPv4 sockaddr structure, even on a system with IPv6 support. */ { memset(&s_in4, 0, sizeof(s_in4)); s_in4.sin_family = AF_INET; s_in4.sin_port = htons(port); s_in4.sin_addr.s_addr = (S_ADDR_TYPE)inet_addr(CCS address); s_ptr = (struct sockaddr *)&s_in4; s_len = sizeof(s_in4); } /* If no connection timeout is set, just call connect() without setting a timer, thereby allowing the inbuilt OS timeout to operate. */ callout_address = string_sprintf("[%s]:%d", address, port); sigalrm_seen = FALSE; if (timeout > 0) ALARM(timeout); #ifdef EXIM_SUPPORT_TFO /* TCP Fast Open, if the system has a cookie from a previous call to this peer, can send data in the SYN packet. The peer can send data before it gets our ACK of its SYN,ACK - the latter is useful for the SMTP banner. Other (than SMTP) cases of TCP connections can possibly use the data-on-syn, so support that too. */ if (fastopen_blob && f.tcp_fastopen_ok) { # ifdef MSG_FASTOPEN /* This is a Linux implementation. */ if ((rc = sendto(sock, fastopen_blob->data, fastopen_blob->len, MSG_FASTOPEN | MSG_DONTWAIT, s_ptr, s_len)) >= 0) /* seen for with-data, experimental TFO option, with-cookie case */ /* seen for with-data, proper TFO opt, with-cookie case */ { DEBUG(D_transport|D_v) debug_printf(" TFO mode connection attempt to %s, %lu data\n", address, (unsigned long)fastopen_blob->len); /*XXX also seen on successful TFO, sigh */ tcp_out_fastopen = fastopen_blob->len > 0 ? TFO_ATTEMPTED_DATA : TFO_ATTEMPTED_NODATA; } else switch (errno) { case EINPROGRESS: /* expected if we had no cookie for peer */ /* seen for no-data, proper TFO option, both cookie-request and with-cookie cases */ /* apparently no visibility of the diffference at this point */ /* seen for with-data, proper TFO opt, cookie-req */ /* with netwk delay, post-conn tcp_info sees unacked 1 for R, 2 for C; code in smtp_out.c */ /* ? older Experimental TFO option behaviour ? */ DEBUG(D_transport|D_v) debug_printf(" TFO mode sendto, %s data: EINPROGRESS\n", fastopen_blob->len > 0 ? "with" : "no"); if (!fastopen_blob->data) { tcp_out_fastopen = TFO_ATTEMPTED_NODATA; /* we tried; unknown if useful yet */ rc = 0; } else /* queue unsent data */ rc = send(sock, fastopen_blob->data, fastopen_blob->len, 0); break; case EOPNOTSUPP: DEBUG(D_transport) debug_printf("Tried TCP Fast Open but apparently not enabled by sysctl\n"); goto legacy_connect; case EPIPE: DEBUG(D_transport) debug_printf("Tried TCP Fast Open but kernel too old to support it\n"); goto legacy_connect; } # elif defined(EXIM_TFO_FREEBSD) /* Re: https://people.freebsd.org/~pkelsey/tfo-tools/tfo-client.c */ if (setsockopt(sock, IPPROTO_TCP, TCP_FASTOPEN, &on, sizeof(on)) < 0) { DEBUG(D_transport) debug_printf("Tried TCP Fast Open but apparently not enabled by sysctl\n"); goto legacy_connect; } if ((rc = sendto(sock, fastopen_blob->data, fastopen_blob->len, 0, s_ptr, s_len)) >= 0) { DEBUG(D_transport|D_v) debug_printf(" TFO mode connection attempt to %s, %lu data\n", address, (unsigned long)fastopen_blob->len); tcp_out_fastopen = fastopen_blob->len > 0 ? TFO_ATTEMPTED_DATA : TFO_ATTEMPTED_NODATA; } # elif defined(EXIM_TFO_CONNECTX) /* MacOS */ sa_endpoints_t ends = { .sae_srcif = 0, .sae_srcaddr = NULL, .sae_srcaddrlen = 0, .sae_dstaddr = s_ptr, .sae_dstaddrlen = s_len }; struct iovec iov = { .iov_base = fastopen_blob->data, .iov_len = fastopen_blob->len }; size_t len; if ((rc = connectx(sock, &ends, SAE_ASSOCID_ANY, CONNECT_DATA_IDEMPOTENT, &iov, 1, &len, NULL)) == 0) { DEBUG(D_transport|D_v) debug_printf(" TFO mode connection attempt to %s, %lu data\n", address, (unsigned long)fastopen_blob->len); tcp_out_fastopen = fastopen_blob->len > 0 ? TFO_ATTEMPTED_DATA : TFO_ATTEMPTED_NODATA; if (len != fastopen_blob->len) DEBUG(D_transport|D_v) debug_printf(" only queued %lu data!\n", (unsigned long)len); } else if (errno == EINPROGRESS) { DEBUG(D_transport|D_v) debug_printf(" TFO mode connectx, %s data: EINPROGRESS\n", fastopen_blob->len > 0 ? "with" : "no"); if (!fastopen_blob->data) { tcp_out_fastopen = TFO_ATTEMPTED_NODATA; /* we tried; unknown if useful yet */ rc = 0; } else /* assume that no data was queued; block in send */ rc = send(sock, fastopen_blob->data, fastopen_blob->len, 0); } # endif } else #endif /*EXIM_SUPPORT_TFO*/ { #if defined(EXIM_SUPPORT_TFO) && !defined(EXIM_TFO_CONNECTX) legacy_connect: #endif DEBUG(D_transport|D_v) if (fastopen_blob) debug_printf(" non-TFO mode connection attempt to %s, %lu data\n", address, (unsigned long)fastopen_blob->len); if ((rc = connect(sock, s_ptr, s_len)) >= 0) if ( fastopen_blob && fastopen_blob->data && fastopen_blob->len && send(sock, fastopen_blob->data, fastopen_blob->len, 0) < 0) rc = -1; } save_errno = errno; ALARM_CLR(0); /* There is a testing facility for simulating a connection timeout, as I can't think of any other way of doing this. It converts a connection refused into a timeout if the timeout is set to 999999. */ if (f.running_in_test_harness && save_errno == ECONNREFUSED && timeout == 999999) { rc = -1; save_errno = EINTR; sigalrm_seen = TRUE; } /* Success */ if (rc >= 0) return 0; /* A failure whose error code is "Interrupted system call" is in fact an externally applied timeout if the signal handler has been run. */ errno = save_errno == EINTR && sigalrm_seen ? ETIMEDOUT : save_errno; return -1; } /************************************************* * Create connected socket to remote host * *************************************************/ /* Create a socket and connect to host (name or number, ipv6 ok) at one of port-range. Arguments: type SOCK_DGRAM or SOCK_STREAM af AF_INET6 or AF_INET for the socket type hostname host name, or ip address (as text) portlo,porthi the remote port range timeout a timeout connhost if not NULL, host_item to be filled in with connection details errstr pointer for allocated string on error fastopen_blob with SOCK_STREAM, if non-null, request TCP Fast Open. Additionally, optional idempotent early-data to send Return: socket fd, or -1 on failure (having allocated an error string) */ int ip_connectedsocket(int type, const uschar * hostname, int portlo, int porthi, int timeout, host_item * connhost, uschar ** errstr, const blob * fastopen_blob) { int namelen; host_item shost; int af = 0, fd, fd4 = -1, fd6 = -1; shost.next = NULL; shost.address = NULL; shost.port = portlo; shost.mx = -1; namelen = Ustrlen(hostname); /* Anything enclosed in [] must be an IP address. */ if (hostname[0] == '[' && hostname[namelen - 1] == ']') { uschar * host = string_copyn(hostname+1, namelen-2); if (string_is_ip_address(host, NULL) == 0) { *errstr = string_sprintf("malformed IP address \"%s\"", hostname); return -1; } shost.name = shost.address = host; } /* Otherwise check for an unadorned IP address */ else if (string_is_ip_address(hostname, NULL) != 0) shost.name = shost.address = string_copyn(hostname, namelen); /* Otherwise lookup IP address(es) from the name */ else { shost.name = string_copyn(hostname, namelen); if (host_find_byname(&shost, NULL, HOST_FIND_QUALIFY_SINGLE, NULL, FALSE) != HOST_FOUND) { *errstr = string_sprintf("no IP address found for host %s", shost.name); return -1; } } /* Try to connect to the server - test each IP till one works */ for (host_item * h = &shost; h; h = h->next) { fd = Ustrchr(h->address, ':') != 0 ? fd6 < 0 ? (fd6 = ip_socket(type, af = AF_INET6)) : fd6 : fd4 < 0 ? (fd4 = ip_socket(type, af = AF_INET )) : fd4; if (fd < 0) { *errstr = string_sprintf("failed to create socket: %s", strerror(errno)); goto bad; } for (int port = portlo; port <= porthi; port++) if (ip_connect(fd, af, h->address, port, timeout, fastopen_blob) == 0) { if (fd != fd6) close(fd6); if (fd != fd4) close(fd4); if (connhost) { h->port = port; *connhost = *h; connhost->next = NULL; } return fd; } } *errstr = string_sprintf("failed to connect to any address for %s: %s", hostname, strerror(errno)); bad: close(fd4); close(fd6); return -1; } /*XXX TFO? */ int ip_tcpsocket(const uschar * hostport, uschar ** errstr, int tmo, host_item * connhost) { int scan; uschar hostname[256]; unsigned int portlow, porthigh; /* extract host and port part */ scan = sscanf(CS hostport, "%255s %u-%u", hostname, &portlow, &porthigh); if (scan != 3) { if (scan != 2) { *errstr = string_sprintf("invalid socket '%s'", hostport); return -1; } porthigh = portlow; } return ip_connectedsocket(SOCK_STREAM, hostname, portlow, porthigh, tmo, connhost, errstr, NULL); } int ip_unixsocket(const uschar * path, uschar ** errstr) { int sock; struct sockaddr_un server; if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) { *errstr = US"can't open UNIX socket."; return -1; } callout_address = string_copy(path); server.sun_family = AF_UNIX; Ustrncpy(US server.sun_path, path, sizeof(server.sun_path)-1); server.sun_path[sizeof(server.sun_path)-1] = '\0'; if (connect(sock, (struct sockaddr *) &server, sizeof(server)) < 0) { int err = errno; (void)close(sock); *errstr = string_sprintf("unable to connect to UNIX socket (%s): %s", path, strerror(err)); return -1; } return sock; } /* spec is either an absolute path (with a leading /), or a host (name or IP) and port (whitespace-separated). The port can be a range, dash-separated, or a single number. For a TCP socket, optionally fill in a host_item. */ int ip_streamsocket(const uschar * spec, uschar ** errstr, int tmo, host_item * connhost) { return *spec == '/' ? ip_unixsocket(spec, errstr) : ip_tcpsocket(spec, errstr, tmo, connhost); } /************************************************* * Set keepalive on a socket * *************************************************/ /* Can be called for both incoming and outgoing sockets. Arguments: sock the socket address the remote host address, for failure logging torf true for outgoing connection, false for incoming Returns: nothing */ void ip_keepalive(int sock, const uschar *address, BOOL torf) { int fodder = 1; if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, US (&fodder), sizeof(fodder)) != 0) log_write(0, LOG_MAIN, "setsockopt(SO_KEEPALIVE) on connection %s %s " "failed: %s", torf? "to":"from", address, strerror(errno)); } /************************************************* * Receive from a socket with timeout * *************************************************/ /* Arguments: fd the file descriptor timelimit the timeout endpoint, seconds-since-epoch Returns: TRUE => ready for i/o FALSE => timed out, or other error */ BOOL fd_ready(int fd, time_t timelimit) { fd_set select_inset; int time_left = timelimit - time(NULL); int rc; if (time_left <= 0) { errno = ETIMEDOUT; return FALSE; } /* Wait until the socket is ready */ do { struct timeval tv = { .tv_sec = time_left, .tv_usec = 0 }; FD_ZERO (&select_inset); FD_SET (fd, &select_inset); /*DEBUG(D_transport) debug_printf("waiting for data on fd\n");*/ rc = select(fd + 1, (SELECT_ARG2_TYPE *)&select_inset, NULL, NULL, &tv); /* If some interrupt arrived, just retry. We presume this to be rare, but it can happen (e.g. the SIGUSR1 signal sent by exiwhat causes select() to exit). Aug 2004: Somebody set up a cron job that ran exiwhat every 2 minutes, making the interrupt not at all rare. Since the timeout is typically more than 2 minutes, the effect was to block the timeout completely. To prevent this happening again, we do an explicit time test and adjust the timeout accordingly */ if (rc < 0 && errno == EINTR) { DEBUG(D_transport) debug_printf("EINTR while waiting for socket data\n"); /* Watch out, 'continue' jumps to the condition, not to the loops top */ if ((time_left = timelimit - time(NULL)) > 0) continue; } if (rc <= 0) { errno = ETIMEDOUT; return FALSE; } /* Checking the FD_ISSET is not enough, if we're interrupted, the select_inset may still contain the 'input'. */ } while (rc < 0 || !FD_ISSET(fd, &select_inset)); return TRUE; } /* The timeout is implemented using select(), and we loop to cover select() getting interrupted, and the possibility of select() returning with a positive result but no ready descriptor. Is this in fact possible? Arguments: cctx the connection context (socket fd, possibly TLS context) buffer to read into bufsize the buffer size timelimit the timeout endpoint, seconds-since-epoch Returns: > 0 => that much data read <= 0 on error or EOF; errno set - zero for EOF */ int ip_recv(client_conn_ctx * cctx, uschar * buffer, int buffsize, time_t timelimit) { int rc; if (!fd_ready(cctx->sock, timelimit)) return -1; /* The socket is ready, read from it (via TLS if it's active). On EOF (i.e. close down of the connection), set errno to zero; otherwise leave it alone. */ #ifndef DISABLE_TLS if (cctx->tls_ctx) /* client TLS */ rc = tls_read(cctx->tls_ctx, buffer, buffsize); else if (tls_in.active.sock == cctx->sock) /* server TLS */ rc = tls_read(NULL, buffer, buffsize); else #endif rc = recv(cctx->sock, buffer, buffsize, 0); if (rc > 0) return rc; if (rc == 0) errno = 0; return -1; } /************************************************* * Lookup address family of potential socket * *************************************************/ /* Given a file-descriptor, check to see if it's a socket and, if so, return the address family; detects IPv4 vs IPv6. If not a socket then return -1. The value 0 is typically AF_UNSPEC, which should not be seen on a connected fd. If the return is -1, the errno will be from getsockname(); probably ENOTSOCK or ECONNRESET. Arguments: socket-or-not fd Returns: address family or -1 */ int ip_get_address_family(int fd) { struct sockaddr_storage ss; socklen_t sslen = sizeof(ss); if (getsockname(fd, (struct sockaddr *) &ss, &sslen) < 0) return -1; return (int) ss.ss_family; } /************************************************* * Lookup DSCP settings for a socket * *************************************************/ struct dscp_name_tableentry { const uschar *name; int value; }; /* Keep both of these tables sorted! */ static struct dscp_name_tableentry dscp_table[] = { #ifdef IPTOS_DSCP_AF11 { CUS"af11", IPTOS_DSCP_AF11 }, { CUS"af12", IPTOS_DSCP_AF12 }, { CUS"af13", IPTOS_DSCP_AF13 }, { CUS"af21", IPTOS_DSCP_AF21 }, { CUS"af22", IPTOS_DSCP_AF22 }, { CUS"af23", IPTOS_DSCP_AF23 }, { CUS"af31", IPTOS_DSCP_AF31 }, { CUS"af32", IPTOS_DSCP_AF32 }, { CUS"af33", IPTOS_DSCP_AF33 }, { CUS"af41", IPTOS_DSCP_AF41 }, { CUS"af42", IPTOS_DSCP_AF42 }, { CUS"af43", IPTOS_DSCP_AF43 }, { CUS"ef", IPTOS_DSCP_EF }, #endif #ifdef IPTOS_LOWCOST { CUS"lowcost", IPTOS_LOWCOST }, #endif { CUS"lowdelay", IPTOS_LOWDELAY }, #ifdef IPTOS_MINCOST { CUS"mincost", IPTOS_MINCOST }, #endif { CUS"reliability", IPTOS_RELIABILITY }, { CUS"throughput", IPTOS_THROUGHPUT } }; static int dscp_table_size = sizeof(dscp_table) / sizeof(struct dscp_name_tableentry); /* DSCP values change by protocol family, and so do the options used for setsockopt(); this utility does all the lookups. It takes an unexpanded option string, expands it, strips off affix whitespace, then checks if it's a number. If all of what's left is a number, then that's how the option will be parsed and success/failure is a range check. If it's not all a number, then it must be a supported keyword. Arguments: dscp_name a string, so far unvalidated af address_family in use level setsockopt level to use optname setsockopt name to use dscp_value value for dscp_name Returns: TRUE if okay to setsockopt(), else FALSE *level and *optname may be set even if FALSE is returned */ BOOL dscp_lookup(const uschar *dscp_name, int af, int *level, int *optname, int *dscp_value) { uschar *dscp_lookup, *p; int first, last; long rawlong; if (af == AF_INET) { *level = IPPROTO_IP; *optname = IP_TOS; } #if HAVE_IPV6 && defined(IPV6_TCLASS) else if (af == AF_INET6) { *level = IPPROTO_IPV6; *optname = IPV6_TCLASS; } #endif else { DEBUG(D_transport) debug_printf("Unhandled address family %d in dscp_lookup()\n", af); return FALSE; } if (!dscp_name) { DEBUG(D_transport) debug_printf("[empty DSCP]\n"); return FALSE; } dscp_lookup = expand_string(US dscp_name); if (dscp_lookup == NULL || *dscp_lookup == '\0') return FALSE; p = dscp_lookup + Ustrlen(dscp_lookup) - 1; while (isspace(*p)) *p-- = '\0'; while (isspace(*dscp_lookup) && dscp_lookup < p) dscp_lookup++; if (*dscp_lookup == '\0') return FALSE; rawlong = Ustrtol(dscp_lookup, &p, 0); if (p != dscp_lookup && *p == '\0') { /* We have six bits available, which will end up shifted to fit in 0xFC mask. RFC 2597 defines the values unshifted. */ if (rawlong < 0 || rawlong > 0x3F) { DEBUG(D_transport) debug_printf("DSCP value %ld out of range, ignored.\n", rawlong); return FALSE; } *dscp_value = rawlong << 2; return TRUE; } first = 0; last = dscp_table_size; while (last > first) { int middle = (first + last)/2; int c = Ustrcmp(dscp_lookup, dscp_table[middle].name); if (c == 0) { *dscp_value = dscp_table[middle].value; return TRUE; } else if (c > 0) first = middle + 1; else last = middle; } return FALSE; } void dscp_list_to_stream(FILE *stream) { for (int i = 0; i < dscp_table_size; ++i) fprintf(stream, "%s\n", dscp_table[i].name); } /* End of ip.c */ /* vi: aw ai sw=2 */