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>
21 /* Whether the given address conforms to the IPv4 address format. */
22 static inline bool is_valid_ipv4_address(const char *address)
24 struct in_addr test_it;
25 return inet_pton(AF_INET, address, &test_it) != 0;
29 * Parse and validate IPv4 address/netmask string.
31 * \param cidr Address in CIDR notation
32 * \param addr Copy of the IPv4 address part of \a cidr
33 * \param addrlen Size of \a addr in bytes
34 * \param netmask Value of the netmask part in \a cidr or the
35 * default of 32 if not specified.
37 * \return Pointer to \a addr if successful, NULL on error.
40 char *parse_cidr(const char *cidr,
41 char *addr, ssize_t addrlen,
45 char *c = addr, *end = c + (addrlen - 1);
49 if (cidr == NULL || addrlen < 1)
52 for (o = cidr; (*c = *o == '/'? '\0' : *o); c++, o++)
57 if (para_atoi32(++o, netmask) < 0 ||
58 *netmask < 0 || *netmask > 0x20)
61 if (is_valid_ipv4_address(addr))
68 static bool is_v4_dot_quad(const char *address)
73 assert(para_regcomp(&r, "^([0-9]+\\.){3}[0-9]+$",
74 REG_EXTENDED | REG_NOSUB) >= 0);
75 result = regexec(&r, address, 0, NULL, 0) == 0;
80 /* Whether a string conforms to IPv6 address format (RFC 4291). */
81 static inline bool is_valid_ipv6_address(const char *address)
83 struct in6_addr test_it;
84 return inet_pton(AF_INET6, address, &test_it) != 0;
88 * Perform basic syntax checking on the host-part of an URL:
90 * - Since ':' is invalid in IPv4 addresses and DNS names, the
91 * presence of ':' causes interpretation as IPv6 address;
92 * - next the first-match-wins algorithm from RFC 3986 is applied;
93 * - else the string is considered as DNS name, to be resolved later.
95 * \param host The host string to check.
96 * \return True if \a host passes the syntax checks.
98 * \sa RFC 3986, 3.2.2; RFC 1123, 2.1; RFC 1034, 3.5.
100 static bool host_string_ok(const char *host)
102 if (host == NULL || *host == '\0')
104 if (strchr(host, ':') != NULL)
105 return is_valid_ipv6_address(host);
106 if (is_v4_dot_quad(host))
107 return is_valid_ipv4_address(host);
112 * Parse and validate URL string.
114 * The URL syntax is loosely based on RFC 3986, supporting one of
115 * - "["host"]"[:port] for native IPv6 addresses and
116 * - host[:port] for IPv4 hostnames and DNS names.
118 * Native IPv6 addresses must be enclosed in square brackets, since
119 * otherwise there is an ambiguity with the port separator `:'.
120 * The 'port' part is always considered to be a number; if absent,
121 * it is set to -1, to indicate that a default port is to be used.
123 * The following are valid examples:
131 * \param url The URL string to take apart.
132 * \param host To return the copied host part of \a url.
133 * \param hostlen The maximum length of \a host.
134 * \param port To return the port number (if any) of \a url.
136 * \return Pointer to \a host, or \p NULL if failed. If \p NULL is returned,
137 * \a host and \a port are undefined. If no port number was present in \a url,
138 * \a port is set to -1.
140 * \sa RFC 3986, 3.2.2/3.2.3.
142 char *parse_url(const char *url,
143 char *host, ssize_t hostlen,
147 char *c = host, *end = c + (hostlen - 1);
151 if (o == NULL || hostlen < 1)
155 for (++o; (*c = *o == ']' ? '\0' : *o); c++, o++)
159 if (*o++ != ']' || (*o != '\0' && *o != ':'))
162 for (; (*c = *o == ':'? '\0' : *o); c++, o++) {
163 if (c == end && o[1])
169 if (para_atoi32(++o, port) < 0 || *port < 0 || *port > 0xffff)
171 if (host_string_ok(host))
179 * Pretty-print a host/port pair.
181 * \param url NULL, or any string accepted by \ref parse_url().
182 * \param default_port Applies if url has no port.
184 * If the url argument is NULL, the function returns the string
185 * 0.0.0.0:default_port. Otherwise it calls \ref parse_url() to check the
186 * syntax of the input string given by url. On errors the string "?" is
187 * returned. Otherwise, if url contains a port, a copy of url is returned. If
188 * no port was supplied, a colon and the default port are appended to url.
190 * \return In all cases the returned string is a allocated with malloc(3) and
191 * has to be freed by the caller.
193 __malloc char *format_url(const char *url, int default_port)
195 char host[MAX_HOSTLEN];
199 return make_message("0.0.0.0:%d", default_port);
200 if (!parse_url(url, host, sizeof(host), &url_port))
201 return make_message("?");
203 return make_message("%s:%d", url, default_port);
205 return para_strdup(url);
209 * Stringify port number, resolve into service name where defined.
211 * \param port 2-byte port number, in host-byte-order.
212 * \param transport Transport protocol name (e.g. "udp", "tcp"), or NULL.
213 * \return Pointer to static result buffer.
215 * \sa getservbyport(3), services(5), nsswitch.conf(5).
217 const char *stringify_port(int port, const char *transport)
219 static char service[NI_MAXSERV];
221 if (port < 0 || port > 0xFFFF) {
222 snprintf(service, sizeof(service), "undefined (%d)", port);
224 struct servent *se = getservbyport(htons(port), transport);
227 snprintf(service, sizeof(service), "%d", port);
229 snprintf(service, sizeof(service), "%s", se->s_name);
235 #define SOCK_DCCP 6 /**< Linux socket type. */
239 * Determine the socket type, given the symbolic name of the transport-layer
240 * protocol. See ip(7), socket(2).
242 static inline int sock_type(const unsigned l4type)
245 case IPPROTO_UDP: return SOCK_DGRAM;
246 case IPPROTO_TCP: return SOCK_STREAM;
247 case IPPROTO_DCCP: return SOCK_DCCP;
249 return -1; /* not supported here */
252 /* Pretty-print transport-layer name. */
253 static const char *layer4_name(const unsigned l4type)
256 case IPPROTO_UDP: return "UDP";
257 case IPPROTO_TCP: return "TCP";
258 case IPPROTO_DCCP: return "DCCP";
260 return "UNKNOWN PROTOCOL";
264 * Flowopts: Transport-layer independent encapsulation of socket options.
266 * These collect individual socket options into a queue, which is disposed of
267 * directly after makesock(). The 'pre_conn_opt' structure is for internal use
268 * only and should not be visible elsewhere.
270 * \sa setsockopt(2), \ref makesock().
272 struct pre_conn_opt {
273 int sock_level; /**< Second argument to setsockopt() */
274 int sock_option; /**< Third argument to setsockopt() */
275 char *opt_name; /**< Stringified \a sock_option */
276 void *opt_val; /**< Fourth argument to setsockopt() */
277 socklen_t opt_len; /**< Fifth argument to setsockopt() */
279 struct list_head node; /**< FIFO, as sockopt order matters. */
283 * List of pre-connection socket options to be set.
285 * This list contains transport-layer independent encapsulation of socket
286 * options that need to be registered prior to setting up a connection.
289 struct list_head sockopts;
293 * Allocate and initialize a flowopt queue.
295 * \return A new structure to be passed to \ref flowopt_add(). It is
296 * automatically deallocated in \ref makesock().
298 struct flowopts *flowopt_new(void)
300 struct flowopts *new = alloc(sizeof(*new));
302 init_list_head(&new->sockopts);
307 * Append new socket option to flowopt queue.
309 * \param fo The flowopt queue to append to.
310 * \param lev Level at which \a opt resides.
311 * \param opt New option to add.
312 * \param name Stringified name of \a opt.
313 * \param val The value to set \a opt to.
314 * \param len Length of \a val.
318 void flowopt_add(struct flowopts *fo, int lev, int opt,
319 const char *name, const void *val, int len)
321 struct pre_conn_opt *new = alloc(sizeof(*new));
323 new->sock_option = opt;
324 new->sock_level = lev;
325 new->opt_name = para_strdup(name);
331 new->opt_val = alloc(len);
333 memcpy(new->opt_val, val, len);
336 list_add_tail(&new->node, &fo->sockopts);
339 /* Set the entire bunch of pre-connection options at once. */
340 static void flowopt_setopts(int sockfd, struct flowopts *fo)
342 struct pre_conn_opt *pc;
347 list_for_each_entry(pc, &fo->sockopts, node)
348 if (setsockopt(sockfd, pc->sock_level, pc->sock_option,
349 pc->opt_val, pc->opt_len) < 0) {
350 PARA_EMERG_LOG("Can not set %s socket option: %s",
351 pc->opt_name, strerror(errno));
357 * Deallocate all resources of a flowopts structure.
359 * \param fo A pointer as returned from flowopt_new().
361 * It's OK to pass \p NULL here in which case the function does nothing.
363 void flowopt_cleanup(struct flowopts *fo)
365 struct pre_conn_opt *cur, *next;
370 list_for_each_entry_safe(cur, next, &fo->sockopts, node) {
379 * Resolve an IPv4/IPv6 address.
381 * \param l4type The layer-4 type (\p IPPROTO_xxx).
382 * \param passive Whether \p AI_PASSIVE should be included as hint.
383 * \param host Remote or local hostname or IPv/6 address string.
384 * \param port_number Used to set the port in each returned address structure.
385 * \param result addrinfo structures are returned here.
387 * The interpretation of \a host depends on the value of \a passive. On a
388 * passive socket host is interpreted as an interface IPv4/6 address (can be
389 * left NULL). On an active socket, \a host is the peer DNS name or IPv4/6
390 * address to connect to.
394 * \sa getaddrinfo(3).
396 int lookup_address(unsigned l4type, bool passive, const char *host,
397 int port_number, struct addrinfo **result)
400 char port[6]; /* port number has at most 5 digits */
401 struct addrinfo *addr = NULL, hints;
404 sprintf(port, "%d", port_number & 0xffff);
405 /* Set up address hint structure */
406 memset(&hints, 0, sizeof(hints));
407 hints.ai_family = AF_UNSPEC;
408 hints.ai_socktype = sock_type(l4type);
410 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
411 * (and only then) pretend to be UDP.
413 if (l4type == IPPROTO_DCCP)
414 hints.ai_socktype = SOCK_DGRAM;
415 /* only use addresses available on the host */
416 hints.ai_flags = AI_ADDRCONFIG;
417 if (passive && host == NULL)
418 hints.ai_flags |= AI_PASSIVE;
419 /* Obtain local/remote address information */
420 ret = getaddrinfo(host, port, &hints, &addr);
422 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s\n",
424 host? host : (passive? "[loopback]" : "[localhost]"),
425 port, gai_strerror(ret));
426 return -E_ADDRESS_LOOKUP;
433 * Create an active or passive socket.
435 * \param l4type \p IPPROTO_TCP, \p IPPROTO_UDP, or \p IPPROTO_DCCP.
436 * \param passive Whether to call bind(2) or connect(2).
437 * \param ai Address information as obtained from \ref lookup_address().
438 * \param fo Socket options to be set before making the connection.
440 * bind(2) is called on passive sockets, and connect(2) on active sockets. The
441 * algorithm tries all possible address combinations until it succeeds. If \a
442 * fo is supplied, options are set but cleanup must be performed in the caller.
444 * \return File descriptor on success, \p E_MAKESOCK on errors.
446 * \sa \ref lookup_address(), \ref makesock(), ip(7), ipv6(7), bind(2),
449 int makesock_addrinfo(unsigned l4type, bool passive, struct addrinfo *ai,
452 int ret = -E_MAKESOCK, on = 1;
454 for (; ai; ai = ai->ai_next) {
456 ret = socket(ai->ai_family, sock_type(l4type), l4type);
458 PARA_NOTICE_LOG("socket(): %s\n", strerror(errno));
462 flowopt_setopts(fd, fo);
464 if (connect(fd, ai->ai_addr, ai->ai_addrlen) < 0) {
465 PARA_NOTICE_LOG("connect(): %s\n",
473 * Reuse the address on passive sockets to avoid failure on
474 * restart (protocols using listen()) and when creating
475 * multiple listener instances (UDP multicast).
477 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on,
479 PARA_NOTICE_LOG("setsockopt(): %s\n", strerror(errno));
483 if (bind(fd, ai->ai_addr, ai->ai_addrlen) < 0) {
484 PARA_NOTICE_LOG("bind(): %s\n", strerror(errno));
494 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
496 * \param l4type The layer-4 type (\p IPPROTO_xxx).
497 * \param passive Whether this is a passive or active socket.
498 * \param host Passed to \ref lookup_address().
499 * \param port_number Passed to \ref lookup_address().
500 * \param fo Passed to \ref makesock_addrinfo().
502 * This creates a ready-made IPv4/v6 socket structure after looking up the
503 * necessary parameters. The function first calls \ref lookup_address() and
504 * passes the address information to makesock_addrinfo() to create and
505 * initialize the socket.
507 * \return The newly created file descriptor on success, a negative error code
510 * \sa \ref lookup_address(), \ref makesock_addrinfo().
512 int makesock(unsigned l4type, bool passive, const char *host, uint16_t port_number,
516 int ret = lookup_address(l4type, passive, host, port_number, &ai);
519 ret = makesock_addrinfo(l4type, passive, ai, fo);
523 PARA_NOTICE_LOG("can not create %s socket %s#%d.\n",
524 layer4_name(l4type), host? host : (passive?
525 "[loopback]" : "[localhost]"), port_number);
531 * Create a passive / listening socket.
533 * \param l4type The transport-layer type (\p IPPROTO_xxx).
534 * \param addr Passed to \ref parse_url() if not NULL.
535 * \param port Ignored if addr contains a port number.
537 * \return Positive integer (socket descriptor) on success, negative value
540 * \sa \ref makesock(), ip(7), ipv6(7), bind(2), listen(2).
542 int para_listen(unsigned l4type, const char *addr, uint16_t port)
544 char host[MAX_HOSTLEN];
545 int ret, fd, addr_port;
548 if (!parse_url(addr, host, sizeof(host), &addr_port))
549 return -ERRNO_TO_PARA_ERROR(EINVAL);
554 fd = makesock(l4type, true /* passive */, addr, port,
555 NULL /* no flowopts */);
557 ret = listen(fd, BACKLOG);
561 return -ERRNO_TO_PARA_ERROR(ret);
563 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
564 layer4_name(l4type), port, fd);
570 * Create a socket which listens on all network addresses.
572 * \param l4type See \ref para_listen().
573 * \param port See \ref para_listen().
575 * This is a simple wrapper for \ref para_listen() which passes a NULL pointer
576 * as the address information.
578 * \return See \ref para_listen().
580 int para_listen_simple(unsigned l4type, uint16_t port)
582 return para_listen(l4type, NULL, port);
585 /* Compute the address-family dependent address length of an IPv4/v6 socket. */
586 static socklen_t salen(const struct sockaddr *sa)
588 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
590 return sa->sa_family == AF_INET6
591 ? sizeof(struct sockaddr_in6)
592 : sizeof(struct sockaddr_in);
595 /* True if ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
596 static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
598 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
600 return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
604 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
605 * ss: Container of IPv4/6 address.
606 * Returns: Pointer to normalized address (may be static storage).
610 static const struct sockaddr *
611 normalize_ip_address(const struct sockaddr_storage *ss)
613 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
615 if (SS_IS_ADDR_V4MAPPED(ss)) {
616 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
617 static struct sockaddr_in ia;
619 ia.sin_family = AF_INET;
620 ia.sin_port = ia6->sin6_port;
621 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
622 return (const struct sockaddr *)&ia;
624 return (const struct sockaddr *)ss;
628 * Generic/fallback MTU values
630 * These are taken from RFC 1122, RFC 2460, and RFC 5405.
631 * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
632 * to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
633 * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
634 * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
635 * UDP senders should use the respective minimum values of EMTU_S.
637 static inline int generic_mtu(const int af_type)
639 return af_type == AF_INET6 ? 1280 : 576;
642 /* Crude approximation of IP header overhead - neglecting options. */
643 static inline int estimated_header_overhead(const int af_type)
645 return af_type == AF_INET6 ? 40 : 20;
649 * Get the maximum transport-layer message size (MMS_S).
651 * \param sockfd The socket file descriptor.
653 * The socket must be connected. See RFC 1122, 3.3.3. If the protocol family
654 * could not be determined, \p AF_INET is assumed.
656 * \return The maximum message size of the address family type.
658 int generic_max_transport_msg_size(int sockfd)
660 struct sockaddr_storage ss = {.ss_family = 0};
661 socklen_t sslen = sizeof(ss);
662 int af_type = AF_INET;
664 if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
665 PARA_ERROR_LOG("can not determine remote address type: %s\n",
667 } else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
668 af_type = ss.ss_family;
670 return generic_mtu(af_type) - estimated_header_overhead(af_type);
674 * Look up the remote side of a connected socket structure.
676 * \param fd The socket descriptor of the connected socket.
678 * \return A static character string identifying hostname and port of the
679 * chosen side in numeric host:port format.
681 * \sa getsockname(2), getpeername(2), \ref parse_url(), getnameinfo(3),
682 * services(5), nsswitch.conf(5).
684 char *remote_name(int fd)
686 struct sockaddr_storage ss = {.ss_family = 0};
687 const struct sockaddr *sa;
688 socklen_t sslen = sizeof(ss);
689 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
690 static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
693 if (getpeername(fd, (struct sockaddr *)&ss, &sslen) < 0) {
694 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
695 fd, strerror(errno));
696 snprintf(output, sizeof(output), "(unknown)");
699 sa = normalize_ip_address(&ss);
700 ret = getnameinfo(sa, salen(sa), hbuf, sizeof(hbuf), sbuf,
701 sizeof(sbuf), NI_NUMERICHOST | NI_NUMERICSERV);
703 PARA_WARNING_LOG("hostname lookup error (%s).\n",
705 snprintf(output, sizeof(output), "(lookup error)");
706 } else if (sa->sa_family == AF_INET6)
707 snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
709 snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
714 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
716 * \param ss Container of IPv4/6 address.
717 * \param ia Extracted IPv4 address (different from 0) or 0 if unsuccessful.
721 void extract_v4_addr(const struct sockaddr_storage *ss, struct in_addr *ia)
723 const struct sockaddr *sa = normalize_ip_address(ss);
725 memset(ia, 0, sizeof(*ia));
726 if (sa->sa_family == AF_INET)
727 *ia = ((struct sockaddr_in *)sa)->sin_addr;
731 * Compare the address part of IPv4/6 addresses.
733 * \param sa1 First address.
734 * \param sa2 Second address.
736 * \return True iff the IP address of \a sa1 and \a sa2 match.
738 bool sockaddr_equal(const struct sockaddr *sa1, const struct sockaddr *sa2)
742 if (sa1->sa_family != sa2->sa_family)
744 if (sa1->sa_family == AF_INET) {
745 struct sockaddr_in *a1 = (typeof(a1))sa1,
746 *a2 = (typeof (a2))sa2;
747 return a1->sin_addr.s_addr == a2->sin_addr.s_addr;
748 } else if (sa1->sa_family == AF_INET6) {
749 struct sockaddr_in6 *a1 = (typeof(a1))sa1,
750 *a2 = (typeof (a2))sa2;
751 return !memcmp(a1, a2, sizeof(*a1));
757 * Receive data from a file descriptor.
759 * \param fd The file descriptor.
760 * \param buf The buffer to write the data to.
761 * \param size The size of \a buf.
763 * Receive at most \a size bytes from file descriptor \a fd.
765 * \return The number of bytes received on success, negative on errors, zero if
766 * the peer has performed an orderly shutdown.
770 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
774 n = recv(fd, buf, size, 0);
776 return -ERRNO_TO_PARA_ERROR(errno);
781 * Receive and write terminating NULL byte.
783 * \param fd The file descriptor.
784 * \param buf The buffer to write the data to.
785 * \param size The size of \a buf.
787 * Read at most \a size - 1 bytes from file descriptor \a fd and
788 * write a NULL byte at the end of the received data.
790 * \return The return value of the underlying call to \a recv_bin_buffer().
792 * \sa \ref recv_bin_buffer()
794 int recv_buffer(int fd, char *buf, size_t size)
799 n = recv_bin_buffer(fd, buf, size - 1);
808 * Wrapper around the accept system call.
810 * \param fd The listening socket.
811 * \param addr Structure which is filled in with the address of the peer socket.
812 * \param size Should contain the size of the structure pointed to by \a addr.
813 * \param new_fd Result pointer.
815 * Accept incoming connections on addr, retry if interrupted.
817 * \return Negative on errors, zero if no connections are present to be accepted,
822 int para_accept(int fd, void *addr, socklen_t size, int *new_fd)
827 ret = accept(fd, (struct sockaddr *) addr, &size);
828 while (ret < 0 && errno == EINTR);
834 if (errno == EAGAIN || errno == EWOULDBLOCK)
836 return -ERRNO_TO_PARA_ERROR(errno);
839 #ifndef DCCP_SOCKOPT_AVAILABLE_CCIDS
840 #define DCCP_SOCKOPT_AVAILABLE_CCIDS 12 /**< List of supported CCIDs. */
844 * Probe the list of DCCP CCIDs configured on this host.
845 * \param ccid_array Pointer to return statically allocated array in.
846 * \return Number of elements returned in \a ccid_array or error.
848 * NB: This feature is only available on Linux > 2.6.30; on older kernels
849 * ENOPROTOOPT ("Protocol not available") will be returned.
851 int dccp_available_ccids(uint8_t **ccid_array)
853 static uint8_t ccids[DCCP_MAX_HOST_CCIDS];
854 socklen_t nccids = sizeof(ccids);
857 ret = fd = makesock(IPPROTO_DCCP, true /* passive */, NULL, 0, NULL);
861 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
862 ccids, &nccids) < 0) {
865 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
867 return -ERRNO_TO_PARA_ERROR(ret);
876 * The buffer size of the sun_path component of struct sockaddr_un.
878 * While glibc doesn't define UNIX_PATH_MAX, it documents it has being limited
879 * to 108 bytes. On NetBSD it is only 104 bytes though. We trust UNIX_PATH_MAX
880 * if it is defined and use the size of the ->sun_path member otherwise. This
881 * should be safe everywhere.
883 #ifndef UNIX_PATH_MAX
884 #define UNIX_PATH_MAX (sizeof(((struct sockaddr_un *)0)->sun_path))
888 * Prepare a structure for AF_UNIX socket addresses.
890 * This just copies name to the sun_path component of u, prepending a zero byte
891 * if abstract sockets are supported.
893 * The first call to this function tries to bind a socket to the abstract name
894 * space. The result of this test is stored in a static variable. Subsequent
895 * calls read this variable and create abstract sockets on systems that support
896 * them. If a NULL pointer is passed as the name, the function only
897 * initializes the static variable.
899 static int init_unix_addr(struct sockaddr_un *u, const char *name)
901 static int use_abstract;
903 memset(u->sun_path, 0, UNIX_PATH_MAX);
904 u->sun_family = PF_UNIX;
905 if (use_abstract == 0) { /* executed only once */
906 int fd = socket(PF_UNIX, SOCK_STREAM, 0);
907 memcpy(u->sun_path, "\0x\0", 3);
908 if (bind(fd, (struct sockaddr *)u, sizeof(*u)) == 0)
909 use_abstract = 1; /* yes */
911 use_abstract = -1; /* no */
913 PARA_NOTICE_LOG("%susing abstract socket namespace\n",
914 use_abstract == 1? "" : "not ");
918 if (strlen(name) + 1 >= UNIX_PATH_MAX)
919 return -E_NAME_TOO_LONG;
920 strcpy(u->sun_path + (use_abstract == 1? 1 : 0), name);
925 * Create a socket for local communication and listen on it.
927 * \param name The socket pathname.
929 * This function creates a passive local socket for sequenced, reliable,
930 * two-way, connection-based byte streams. The socket file descriptor is set to
931 * nonblocking mode and listen(2) is called to prepare the socket for
932 * accepting incoming connection requests.
934 * \return The file descriptor on success, negative error code on failure.
936 * \sa socket(2), \sa bind(2), \sa chmod(2), listen(2), unix(7).
938 int create_local_socket(const char *name)
940 struct sockaddr_un unix_addr;
943 ret = init_unix_addr(&unix_addr, name);
944 if (ret <= 0) /* error, or name was NULL */
946 ret = socket(PF_UNIX, SOCK_STREAM, 0);
948 return -ERRNO_TO_PARA_ERROR(errno);
950 ret = mark_fd_nonblocking(fd);
953 ret = bind(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr));
955 ret = -ERRNO_TO_PARA_ERROR(errno);
958 if (unix_addr.sun_path[0] != 0) { /* pathname socket */
959 mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP
962 if (chmod(name, mode) < 0)
965 if (listen(fd , 5) < 0) {
966 ret = -ERRNO_TO_PARA_ERROR(errno);
976 * Prepare, create, and connect to a Unix domain socket for local communication.
978 * \param name The socket pathname.
980 * This function creates a local socket for sequenced, reliable, two-way,
981 * connection-based byte streams.
983 * \return The file descriptor of the connected socket on success, negative on
986 * \sa \ref create_local_socket(), unix(7), connect(2).
988 int connect_local_socket(const char *name)
990 struct sockaddr_un unix_addr;
993 PARA_DEBUG_LOG("connecting to %s\n", name);
994 fd = socket(PF_UNIX, SOCK_STREAM, 0);
996 return -ERRNO_TO_PARA_ERROR(errno);
997 ret = init_unix_addr(&unix_addr, name);
1000 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) != -1)
1002 ret = -ERRNO_TO_PARA_ERROR(errno);
1009 ssize_t send_cred_buffer(int sock, char *buf)
1011 return write_buffer(sock, buf);
1013 int recv_cred_buffer(int fd, char *buf, size_t size)
1015 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
1017 #else /* HAVE_UCRED */
1020 * Send a buffer and the credentials of the current process to a socket.
1022 * \param sock The file descriptor of the sending socket.
1023 * \param buf The zero-terminated buffer to send.
1025 * \return On success, this call returns the number of bytes sent. On errors,
1026 * \p -E_SENDMSG is returned.
1028 * \sa \ref recv_cred_buffer, sendmsg(2), socket(7), unix(7).
1030 ssize_t send_cred_buffer(int sock, char *buf)
1032 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
1034 struct cmsghdr *cmsg;
1035 static struct iovec iov;
1041 iov.iov_len = strlen(buf);
1045 /* compose the message */
1046 memset(&msg, 0, sizeof(msg));
1049 msg.msg_control = control;
1050 msg.msg_controllen = sizeof(control);
1051 /* attach the ucred struct */
1052 cmsg = CMSG_FIRSTHDR(&msg);
1053 cmsg->cmsg_level = SOL_SOCKET;
1054 cmsg->cmsg_type = SCM_CREDENTIALS;
1055 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
1056 *(struct ucred *)CMSG_DATA(cmsg) = c;
1057 msg.msg_controllen = cmsg->cmsg_len;
1058 ret = sendmsg(sock, &msg, 0);
1064 static void dispose_fds(int *fds, unsigned num)
1068 for (i = 0; i < num; i++)
1073 * Receive a buffer and the Unix credentials of the sending process.
1075 * \param fd The file descriptor of the receiving socket.
1076 * \param buf The buffer to store the received message.
1077 * \param size The length of \a buf in bytes.
1079 * \return Negative on errors, the user id of the sending process on success.
1081 * \sa \ref send_cred_buffer and the references given there.
1083 int recv_cred_buffer(int fd, char *buf, size_t size)
1085 char control[255] __a_aligned(8);
1087 struct cmsghdr *cmsg;
1093 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
1094 memset(&msg, 0, sizeof(msg));
1095 memset(buf, 0, size);
1100 msg.msg_control = control;
1101 msg.msg_controllen = sizeof(control);
1102 if (recvmsg(fd, &msg, 0) < 0)
1104 result = -E_SCM_CREDENTIALS;
1105 cmsg = CMSG_FIRSTHDR(&msg);
1107 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
1108 == SCM_CREDENTIALS) {
1109 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
1112 if (cmsg->cmsg_level == SOL_SOCKET
1113 && cmsg->cmsg_type == SCM_RIGHTS) {
1114 dispose_fds((int *)CMSG_DATA(cmsg),
1115 (cmsg->cmsg_len - CMSG_LEN(0))
1118 cmsg = CMSG_NXTHDR(&msg, cmsg);
1122 #endif /* HAVE_UCRED */