1 /* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
3 /** \file net.c Networking-related helper functions. */
7 #include <netinet/in.h>
10 #include <sys/types.h>
11 #include <sys/socket.h>
14 /* At least NetBSD needs these. */
22 #define AI_ADDRCONFIG 0
34 * Parse and validate IPv4 address/netmask string.
36 * \param cidr Address in CIDR notation
37 * \param addr Copy of the IPv4 address part of \a cidr
38 * \param addrlen Size of \a addr in bytes
39 * \param netmask Value of the netmask part in \a cidr or the
40 * default of 32 if not specified.
42 * \return Pointer to \a addr if successful, NULL on error.
45 char *parse_cidr(const char *cidr,
46 char *addr, ssize_t addrlen,
50 char *c = addr, *end = c + (addrlen - 1);
54 if (cidr == NULL || addrlen < 1)
57 for (o = cidr; (*c = *o == '/'? '\0' : *o); c++, o++)
62 if (para_atoi32(++o, netmask) < 0 ||
63 *netmask < 0 || *netmask > 0x20)
66 if (is_valid_ipv4_address(addr))
75 * Match string as a candidate IPv4 address.
77 * \param address The string to match.
78 * \return True if \a address has "dot-quad" format.
80 static bool is_v4_dot_quad(const char *address)
85 assert(para_regcomp(&r, "^([0-9]+\\.){3}[0-9]+$",
86 REG_EXTENDED | REG_NOSUB) >= 0);
87 result = regexec(&r, address, 0, NULL, 0) == 0;
93 * Perform basic syntax checking on the host-part of an URL:
95 * - Since ':' is invalid in IPv4 addresses and DNS names, the
96 * presence of ':' causes interpretation as IPv6 address;
97 * - next the first-match-wins algorithm from RFC 3986 is applied;
98 * - else the string is considered as DNS name, to be resolved later.
100 * \param host The host string to check.
101 * \return True if \a host passes the syntax checks.
103 * \sa RFC 3986, 3.2.2; RFC 1123, 2.1; RFC 1034, 3.5.
105 static bool host_string_ok(const char *host)
107 if (host == NULL || *host == '\0')
109 if (strchr(host, ':') != NULL)
110 return is_valid_ipv6_address(host);
111 if (is_v4_dot_quad(host))
112 return is_valid_ipv4_address(host);
117 * Parse and validate URL string.
119 * The URL syntax is loosely based on RFC 3986, supporting one of
120 * - "["host"]"[:port] for native IPv6 addresses and
121 * - host[:port] for IPv4 hostnames and DNS names.
123 * Native IPv6 addresses must be enclosed in square brackets, since
124 * otherwise there is an ambiguity with the port separator `:'.
125 * The 'port' part is always considered to be a number; if absent,
126 * it is set to -1, to indicate that a default port is to be used.
128 * The following are valid examples:
136 * \param url The URL string to take apart.
137 * \param host To return the copied host part of \a url.
138 * \param hostlen The maximum length of \a host.
139 * \param port To return the port number (if any) of \a url.
141 * \return Pointer to \a host, or \p NULL if failed. If \p NULL is returned,
142 * \a host and \a port are undefined. If no port number was present in \a url,
143 * \a port is set to -1.
145 * \sa RFC 3986, 3.2.2/3.2.3.
147 char *parse_url(const char *url,
148 char *host, ssize_t hostlen,
152 char *c = host, *end = c + (hostlen - 1);
156 if (o == NULL || hostlen < 1)
160 for (++o; (*c = *o == ']' ? '\0' : *o); c++, o++)
164 if (*o++ != ']' || (*o != '\0' && *o != ':'))
167 for (; (*c = *o == ':'? '\0' : *o); c++, o++) {
168 if (c == end && o[1])
174 if (para_atoi32(++o, port) < 0 || *port < 0 || *port > 0xffff)
176 if (host_string_ok(host))
184 * Stringify port number, resolve into service name where defined.
186 * \param port 2-byte port number, in host-byte-order.
187 * \param transport Transport protocol name (e.g. "udp", "tcp"), or NULL.
188 * \return Pointer to static result buffer.
190 * \sa getservent(3), services(5), nsswitch.conf(5).
192 const char *stringify_port(int port, const char *transport)
194 static char service[NI_MAXSERV];
196 if (port < 0 || port > 0xFFFF) {
197 snprintf(service, sizeof(service), "undefined (%d)", port);
199 struct servent *se = getservbyport(htons(port), transport);
202 snprintf(service, sizeof(service), "%d", port);
204 snprintf(service, sizeof(service), "%s", se->s_name);
210 * Determine the socket type for a given layer-4 protocol.
212 * \param l4type The symbolic name of the transport-layer protocol.
214 * \sa ip(7), socket(2).
216 static inline int sock_type(const unsigned l4type)
219 case IPPROTO_UDP: return SOCK_DGRAM;
220 case IPPROTO_TCP: return SOCK_STREAM;
221 case IPPROTO_DCCP: return SOCK_DCCP;
223 return -1; /* not supported here */
227 * Pretty-print transport-layer name.
229 static const char *layer4_name(const unsigned l4type)
232 case IPPROTO_UDP: return "UDP";
233 case IPPROTO_TCP: return "TCP";
234 case IPPROTO_DCCP: return "DCCP";
236 return "UNKNOWN PROTOCOL";
240 * Flowopts: Transport-layer independent encapsulation of socket options.
242 * These collect individual socket options into a queue, which is disposed of
243 * directly after makesock(). The 'pre_conn_opt' structure is for internal use
244 * only and should not be visible elsewhere.
246 * \sa setsockopt(2), \ref makesock().
248 struct pre_conn_opt {
249 int sock_level; /**< Second argument to setsockopt() */
250 int sock_option; /**< Third argument to setsockopt() */
251 char *opt_name; /**< Stringified \a sock_option */
252 void *opt_val; /**< Fourth argument to setsockopt() */
253 socklen_t opt_len; /**< Fifth argument to setsockopt() */
255 struct list_head node; /**< FIFO, as sockopt order matters. */
258 /** FIFO list of pre-connection socket options to be set */
260 struct list_head sockopts;
264 * Allocate and initialize a flowopt queue.
266 * \return A new structure to be passed to \ref flowopt_add(). It is
267 * automatically deallocated in \ref makesock().
269 struct flowopts *flowopt_new(void)
271 struct flowopts *new = para_malloc(sizeof(*new));
273 INIT_LIST_HEAD(&new->sockopts);
278 * Append new socket option to flowopt queue.
280 * \param fo The flowopt queue to append to.
281 * \param lev Level at which \a opt resides.
282 * \param opt New option to add.
283 * \param name Stringified name of \a opt.
284 * \param val The value to set \a opt to.
285 * \param len Length of \a val.
289 void flowopt_add(struct flowopts *fo, int lev, int opt,
290 const char *name, const void *val, int len)
292 struct pre_conn_opt *new = para_malloc(sizeof(*new));
294 new->sock_option = opt;
295 new->sock_level = lev;
296 new->opt_name = para_strdup(name);
302 new->opt_val = para_malloc(len);
304 memcpy(new->opt_val, val, len);
307 list_add_tail(&new->node, &fo->sockopts);
310 /** Set the entire bunch of pre-connection options at once. */
311 static void flowopt_setopts(int sockfd, struct flowopts *fo)
313 struct pre_conn_opt *pc;
318 list_for_each_entry(pc, &fo->sockopts, node)
319 if (setsockopt(sockfd, pc->sock_level, pc->sock_option,
320 pc->opt_val, pc->opt_len) < 0) {
321 PARA_EMERG_LOG("Can not set %s socket option: %s",
322 pc->opt_name, strerror(errno));
328 * Deallocate all resources of a flowopts structure.
330 * \param fo A pointer as returned from flowopt_new().
332 * It's OK to pass \p NULL here in which case the function does nothing.
334 void flowopt_cleanup(struct flowopts *fo)
336 struct pre_conn_opt *cur, *next;
341 list_for_each_entry_safe(cur, next, &fo->sockopts, node) {
350 * Resolve an IPv4/IPv6 address.
352 * \param l4type The layer-4 type (\p IPPROTO_xxx).
353 * \param passive Whether \p AI_PASSIVE should be included as hint.
354 * \param host Remote or local hostname or IPv/6 address string.
355 * \param port_number Used to set the port in each returned address structure.
356 * \param result addrinfo structures are returned here.
358 * The interpretation of \a host depends on the value of \a passive. On a
359 * passive socket host is interpreted as an interface IPv4/6 address (can be
360 * left NULL). On an active socket, \a host is the peer DNS name or IPv4/6
361 * address to connect to.
365 * \sa getaddrinfo(3).
367 int lookup_address(unsigned l4type, bool passive, const char *host,
368 int port_number, struct addrinfo **result)
371 char port[6]; /* port number has at most 5 digits */
372 struct addrinfo *addr = NULL, hints;
375 sprintf(port, "%d", port_number & 0xffff);
376 /* Set up address hint structure */
377 memset(&hints, 0, sizeof(hints));
378 hints.ai_family = AF_UNSPEC;
379 hints.ai_socktype = sock_type(l4type);
381 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
382 * (and only then) pretend to be UDP.
384 if (l4type == IPPROTO_DCCP)
385 hints.ai_socktype = SOCK_DGRAM;
386 /* only use addresses available on the host */
387 hints.ai_flags = AI_ADDRCONFIG;
388 if (passive && host == NULL)
389 hints.ai_flags |= AI_PASSIVE;
390 /* Obtain local/remote address information */
391 ret = getaddrinfo(host, port, &hints, &addr);
393 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s\n",
395 host? host : (passive? "[loopback]" : "[localhost]"),
396 port, gai_strerror(ret));
397 return -E_ADDRESS_LOOKUP;
404 * Create an active or passive socket.
406 * \param l4type \p IPPROTO_TCP, \p IPPROTO_UDP, or \p IPPROTO_DCCP.
407 * \param passive Whether to call bind(2) or connect(2).
408 * \param ai Address information as obtained from \ref lookup_address().
409 * \param fo Socket options to be set before making the connection.
411 * bind(2) is called on passive sockets, and connect(2) on active sockets. The
412 * algorithm tries all possible address combinations until it succeeds. If \a
413 * fo is supplied, options are set but cleanup must be performed in the caller.
415 * \return File descriptor on success, \p E_MAKESOCK on errors.
417 * \sa \ref lookup_address(), \ref makesock(), ip(7), ipv6(7), bind(2),
420 int makesock_addrinfo(unsigned l4type, bool passive, struct addrinfo *ai,
423 int ret = -E_MAKESOCK, on = 1;
425 for (; ai; ai = ai->ai_next) {
427 ret = socket(ai->ai_family, sock_type(l4type), l4type);
429 PARA_NOTICE_LOG("socket(): %s\n", strerror(errno));
433 flowopt_setopts(fd, fo);
435 if (connect(fd, ai->ai_addr, ai->ai_addrlen) < 0) {
436 PARA_NOTICE_LOG("connect(): %s\n",
444 * Reuse the address on passive sockets to avoid failure on
445 * restart (protocols using listen()) and when creating
446 * multiple listener instances (UDP multicast).
448 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on,
450 PARA_NOTICE_LOG("setsockopt(): %s\n", strerror(errno));
454 if (bind(fd, ai->ai_addr, ai->ai_addrlen) < 0) {
455 PARA_NOTICE_LOG("bind(): %s\n", strerror(errno));
465 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
467 * \param l4type The layer-4 type (\p IPPROTO_xxx).
468 * \param passive Whether this is a passive or active socket.
469 * \param host Passed to \ref lookup_address().
470 * \param port_number Passed to \ref lookup_address().
471 * \param fo Passed to \ref makesock_addrinfo().
473 * This creates a ready-made IPv4/v6 socket structure after looking up the
474 * necessary parameters. The function first calls \ref lookup_address() and
475 * passes the address information to makesock_addrinfo() to create and
476 * initialize the socket.
478 * \return The newly created file descriptor on success, a negative error code
481 * \sa \ref lookup_address(), \ref makesock_addrinfo().
483 int makesock(unsigned l4type, bool passive, const char *host, uint16_t port_number,
487 int ret = lookup_address(l4type, passive, host, port_number, &ai);
490 ret = makesock_addrinfo(l4type, passive, ai, fo);
494 PARA_ERROR_LOG("can not create %s socket %s#%d.\n",
495 layer4_name(l4type), host? host : (passive?
496 "[loopback]" : "[localhost]"), port_number);
502 * Create a passive / listening socket.
504 * \param l4type The transport-layer type (\p IPPROTO_xxx).
505 * \param addr Passed to \ref parse_url() if not NULL.
506 * \param port Ignored if addr contains a port number.
508 * \return Positive integer (socket descriptor) on success, negative value
511 * \sa \ref makesock(), ip(7), ipv6(7), bind(2), listen(2).
513 int para_listen(unsigned l4type, const char *addr, uint16_t port)
515 char host[MAX_HOSTLEN];
516 int ret, fd, addr_port;
519 if (!parse_url(addr, host, sizeof(host), &addr_port))
520 return -ERRNO_TO_PARA_ERROR(EINVAL);
525 fd = makesock(l4type, true /* passive */, addr, port,
526 NULL /* no flowopts */);
528 ret = listen(fd, BACKLOG);
532 return -ERRNO_TO_PARA_ERROR(ret);
534 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
535 layer4_name(l4type), port, fd);
541 * Create a socket which listens on all network addresses.
543 * \param l4type See \ref para_listen().
544 * \param port See \ref para_listen().
546 * This is a simple wrapper for \ref para_listen() which passes a NULL pointer
547 * as the address information.
549 * \return See \ref para_listen().
551 int para_listen_simple(unsigned l4type, uint16_t port)
553 return para_listen(l4type, NULL, port);
557 * Determine IPv4/v6 socket address length.
558 * \param sa Container of IPv4 or IPv6 address.
559 * \return Address-family dependent address length.
561 static socklen_t salen(const struct sockaddr *sa)
563 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
565 return sa->sa_family == AF_INET6
566 ? sizeof(struct sockaddr_in6)
567 : sizeof(struct sockaddr_in);
570 /** True if @ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
571 static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
573 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
575 return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
579 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
580 * \param ss Container of IPv4/6 address.
581 * \return Pointer to normalized address (may be static storage).
585 static const struct sockaddr *
586 normalize_ip_address(const struct sockaddr_storage *ss)
588 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
590 if (SS_IS_ADDR_V4MAPPED(ss)) {
591 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
592 static struct sockaddr_in ia;
594 ia.sin_family = AF_INET;
595 ia.sin_port = ia6->sin6_port;
596 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
597 return (const struct sockaddr *)&ia;
599 return (const struct sockaddr *)ss;
603 * Generic/fallback MTU values
605 * These are taken from RFC 1122, RFC 2460, and RFC 5405.
606 * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
607 * to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
608 * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
609 * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
610 * UDP senders should use the respective minimum values of EMTU_S.
612 static inline int generic_mtu(const int af_type)
614 return af_type == AF_INET6 ? 1280 : 576;
617 /** Crude approximation of IP header overhead - neglecting options. */
618 static inline int estimated_header_overhead(const int af_type)
620 return af_type == AF_INET6 ? 40 : 20;
624 * Get the maximum transport-layer message size (MMS_S).
626 * \param sockfd The socket file descriptor.
628 * The socket must be connected. See RFC 1122, 3.3.3. If the protocol family
629 * could not be determined, \p AF_INET is assumed.
631 * \return The maximum message size of the address family type.
633 int generic_max_transport_msg_size(int sockfd)
635 struct sockaddr_storage ss = {.ss_family = 0};
636 socklen_t sslen = sizeof(ss);
637 int af_type = AF_INET;
639 if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
640 PARA_ERROR_LOG("can not determine remote address type: %s\n",
642 } else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
643 af_type = ss.ss_family;
645 return generic_mtu(af_type) - estimated_header_overhead(af_type);
649 * Look up the remote side of a connected socket structure.
651 * \param fd The socket descriptor of the connected socket.
653 * \return A static character string identifying hostname and port of the
654 * chosen side in numeric host:port format.
656 * \sa getsockname(2), getpeername(2), \ref parse_url(), getnameinfo(3),
657 * services(5), nsswitch.conf(5).
659 char *remote_name(int fd)
661 struct sockaddr_storage ss = {.ss_family = 0};
662 const struct sockaddr *sa;
663 socklen_t sslen = sizeof(ss);
664 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
665 static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
668 if (getpeername(fd, (struct sockaddr *)&ss, &sslen) < 0) {
669 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
670 fd, strerror(errno));
671 snprintf(output, sizeof(output), "(unknown)");
674 sa = normalize_ip_address(&ss);
675 ret = getnameinfo(sa, salen(sa), hbuf, sizeof(hbuf), sbuf,
676 sizeof(sbuf), NI_NUMERICHOST | NI_NUMERICSERV);
678 PARA_WARNING_LOG("hostname lookup error (%s).\n",
680 snprintf(output, sizeof(output), "(lookup error)");
681 } else if (sa->sa_family == AF_INET6)
682 snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
684 snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
689 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
691 * \param ss Container of IPv4/6 address.
692 * \param ia Extracted IPv4 address (different from 0) or 0 if unsuccessful.
696 void extract_v4_addr(const struct sockaddr_storage *ss, struct in_addr *ia)
698 const struct sockaddr *sa = normalize_ip_address(ss);
700 memset(ia, 0, sizeof(*ia));
701 if (sa->sa_family == AF_INET)
702 *ia = ((struct sockaddr_in *)sa)->sin_addr;
706 * Compare the address part of IPv4/6 addresses.
708 * \param sa1 First address.
709 * \param sa2 Second address.
711 * \return True iff the IP address of \a sa1 and \a sa2 match.
713 bool sockaddr_equal(const struct sockaddr *sa1, const struct sockaddr *sa2)
717 if (sa1->sa_family != sa2->sa_family)
719 if (sa1->sa_family == AF_INET) {
720 struct sockaddr_in *a1 = (typeof(a1))sa1,
721 *a2 = (typeof (a2))sa2;
722 return a1->sin_addr.s_addr == a2->sin_addr.s_addr;
723 } else if (sa1->sa_family == AF_INET6) {
724 struct sockaddr_in6 *a1 = (typeof(a1))sa1,
725 *a2 = (typeof (a2))sa2;
726 return !memcmp(a1, a2, sizeof(*a1));
732 * Receive data from a file descriptor.
734 * \param fd The file descriptor.
735 * \param buf The buffer to write the data to.
736 * \param size The size of \a buf.
738 * Receive at most \a size bytes from file descriptor \a fd.
740 * \return The number of bytes received on success, negative on errors, zero if
741 * the peer has performed an orderly shutdown.
745 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
749 n = recv(fd, buf, size, 0);
751 return -ERRNO_TO_PARA_ERROR(errno);
756 * Receive and write terminating NULL byte.
758 * \param fd The file descriptor.
759 * \param buf The buffer to write the data to.
760 * \param size The size of \a buf.
762 * Read at most \a size - 1 bytes from file descriptor \a fd and
763 * write a NULL byte at the end of the received data.
765 * \return The return value of the underlying call to \a recv_bin_buffer().
767 * \sa \ref recv_bin_buffer()
769 int recv_buffer(int fd, char *buf, size_t size)
774 n = recv_bin_buffer(fd, buf, size - 1);
783 * Wrapper around the accept system call.
785 * \param fd The listening socket.
786 * \param rfds An optional fd_set pointer.
787 * \param addr Structure which is filled in with the address of the peer socket.
788 * \param size Should contain the size of the structure pointed to by \a addr.
789 * \param new_fd Result pointer.
791 * Accept incoming connections on \a addr, retry if interrupted. If \a rfds is
792 * not \p NULL, return 0 if \a fd is not set in \a rfds without calling accept().
794 * \return Negative on errors, zero if no connections are present to be accepted,
799 int para_accept(int fd, fd_set *rfds, void *addr, socklen_t size, int *new_fd)
803 if (rfds && !FD_ISSET(fd, rfds))
806 ret = accept(fd, (struct sockaddr *) addr, &size);
807 while (ret < 0 && errno == EINTR);
813 if (errno == EAGAIN || errno == EWOULDBLOCK)
815 return -ERRNO_TO_PARA_ERROR(errno);
819 * Probe the list of DCCP CCIDs configured on this host.
820 * \param ccid_array Pointer to return statically allocated array in.
821 * \return Number of elements returned in \a ccid_array or error.
823 * NB: This feature is only available on Linux > 2.6.30; on older kernels
824 * ENOPROTOOPT ("Protocol not available") will be returned.
826 int dccp_available_ccids(uint8_t **ccid_array)
828 static uint8_t ccids[DCCP_MAX_HOST_CCIDS];
829 socklen_t nccids = sizeof(ccids);
832 ret = fd = makesock(IPPROTO_DCCP, 1, NULL, 0, NULL);
836 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
837 ccids, &nccids) < 0) {
840 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
842 return -ERRNO_TO_PARA_ERROR(ret);
851 * Prepare a structure for AF_UNIX socket addresses.
853 * This just copies name to the sun_path component of u, prepending a zero byte
854 * if abstract sockets are supported.
856 * The first call to this function tries to bind a socket to the abstract name
857 * space. The result of this test is stored in a static variable. Subsequent
858 * calls read this variable and create abstract sockets on systems that support
861 static int init_unix_addr(struct sockaddr_un *u, const char *name)
863 static int use_abstract;
865 if (strlen(name) + 1 >= UNIX_PATH_MAX)
866 return -E_NAME_TOO_LONG;
867 memset(u->sun_path, 0, UNIX_PATH_MAX);
868 u->sun_family = PF_UNIX;
869 if (use_abstract == 0) { /* executed only once */
870 int fd = socket(PF_UNIX, SOCK_STREAM, 0);
871 memcpy(u->sun_path, "\0x\0", 3);
872 if (bind(fd, (struct sockaddr *)u, sizeof(*u)) == 0)
873 use_abstract = 1; /* yes */
875 use_abstract = -1; /* no */
877 PARA_NOTICE_LOG("%susing abstract socket namespace\n",
878 use_abstract == 1? "" : "not ");
880 strcpy(u->sun_path + (use_abstract == 1? 1 : 0), name);
885 * Create a socket for local communication and listen on it.
887 * \param name The socket pathname.
889 * This function creates a passive local socket for sequenced, reliable,
890 * two-way, connection-based byte streams. The socket file descriptor is set to
891 * nonblocking mode and listen(2) is called to prepare the socket for
892 * accepting incoming connection requests.
894 * \return The file descriptor on success, negative error code on failure.
896 * \sa socket(2), \sa bind(2), \sa chmod(2), listen(2), unix(7).
898 int create_local_socket(const char *name)
900 struct sockaddr_un unix_addr;
903 ret = init_unix_addr(&unix_addr, name);
906 ret = socket(PF_UNIX, SOCK_STREAM, 0);
908 return -ERRNO_TO_PARA_ERROR(errno);
910 ret = mark_fd_nonblocking(fd);
913 ret = bind(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr));
915 ret = -ERRNO_TO_PARA_ERROR(errno);
918 if (unix_addr.sun_path[0] != 0) { /* pathname socket */
919 mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP
922 if (chmod(name, mode) < 0)
925 if (listen(fd , 5) < 0) {
926 ret = -ERRNO_TO_PARA_ERROR(errno);
936 * Prepare, create, and connect to a Unix domain socket for local communication.
938 * \param name The socket pathname.
940 * This function creates a local socket for sequenced, reliable, two-way,
941 * connection-based byte streams.
943 * \return The file descriptor of the connected socket on success, negative on
946 * \sa \ref create_local_socket(), unix(7), connect(2).
948 int connect_local_socket(const char *name)
950 struct sockaddr_un unix_addr;
953 PARA_DEBUG_LOG("connecting to %s\n", name);
954 fd = socket(PF_UNIX, SOCK_STREAM, 0);
956 return -ERRNO_TO_PARA_ERROR(errno);
957 ret = init_unix_addr(&unix_addr, name);
960 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) != -1)
962 ret = -ERRNO_TO_PARA_ERROR(errno);
969 ssize_t send_cred_buffer(int sock, char *buf)
971 return write_buffer(sock, buf);
973 int recv_cred_buffer(int fd, char *buf, size_t size)
975 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
977 #else /* HAVE_UCRED */
980 * Send a buffer and the credentials of the current process to a socket.
982 * \param sock The file descriptor of the sending socket.
983 * \param buf The zero-terminated buffer to send.
985 * \return On success, this call returns the number of bytes sent. On errors,
986 * \p -E_SENDMSG is returned.
988 * \sa \ref recv_cred_buffer, sendmsg(2), socket(7), unix(7).
990 ssize_t send_cred_buffer(int sock, char *buf)
992 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
994 struct cmsghdr *cmsg;
995 static struct iovec iov;
1001 iov.iov_len = strlen(buf);
1005 /* compose the message */
1006 memset(&msg, 0, sizeof(msg));
1009 msg.msg_control = control;
1010 msg.msg_controllen = sizeof(control);
1011 /* attach the ucred struct */
1012 cmsg = CMSG_FIRSTHDR(&msg);
1013 cmsg->cmsg_level = SOL_SOCKET;
1014 cmsg->cmsg_type = SCM_CREDENTIALS;
1015 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
1016 *(struct ucred *)CMSG_DATA(cmsg) = c;
1017 msg.msg_controllen = cmsg->cmsg_len;
1018 ret = sendmsg(sock, &msg, 0);
1024 static void dispose_fds(int *fds, unsigned num)
1028 for (i = 0; i < num; i++)
1033 * Receive a buffer and the Unix credentials of the sending process.
1035 * \param fd The file descriptor of the receiving socket.
1036 * \param buf The buffer to store the received message.
1037 * \param size The length of \a buf in bytes.
1039 * \return Negative on errors, the user id of the sending process on success.
1041 * \sa \ref send_cred_buffer and the references given there.
1043 int recv_cred_buffer(int fd, char *buf, size_t size)
1045 char control[255] __a_aligned(8);
1047 struct cmsghdr *cmsg;
1053 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
1054 memset(&msg, 0, sizeof(msg));
1055 memset(buf, 0, size);
1060 msg.msg_control = control;
1061 msg.msg_controllen = sizeof(control);
1062 if (recvmsg(fd, &msg, 0) < 0)
1064 result = -E_SCM_CREDENTIALS;
1065 cmsg = CMSG_FIRSTHDR(&msg);
1067 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
1068 == SCM_CREDENTIALS) {
1069 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
1072 if (cmsg->cmsg_level == SOL_SOCKET
1073 && cmsg->cmsg_type == SCM_RIGHTS) {
1074 dispose_fds((int *)CMSG_DATA(cmsg),
1075 (cmsg->cmsg_len - CMSG_LEN(0))
1078 cmsg = CMSG_NXTHDR(&msg, cmsg);
1082 #endif /* HAVE_UCRED */