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);
431 flowopt_setopts(fd, fo);
433 if (connect(fd, ai->ai_addr, ai->ai_addrlen) == 0)
439 * Reuse the address on passive sockets to avoid failure on
440 * restart (protocols using listen()) and when creating
441 * multiple listener instances (UDP multicast).
443 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on,
448 if (bind(fd, ai->ai_addr, ai->ai_addrlen) < 0) {
458 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
460 * \param l4type The layer-4 type (\p IPPROTO_xxx).
461 * \param passive Whether this is a passive or active socket.
462 * \param host Passed to \ref lookup_address().
463 * \param port_number Passed to \ref lookup_address().
464 * \param fo Passed to \ref makesock_addrinfo().
466 * This creates a ready-made IPv4/v6 socket structure after looking up the
467 * necessary parameters. The function first calls \ref lookup_address() and
468 * passes the address information to makesock_addrinfo() to create and
469 * initialize the socket.
471 * \return The newly created file descriptor on success, a negative error code
474 * \sa \ref lookup_address(), \ref makesock_addrinfo().
476 int makesock(unsigned l4type, bool passive, const char *host, uint16_t port_number,
480 int ret = lookup_address(l4type, passive, host, port_number, &ai);
483 ret = makesock_addrinfo(l4type, passive, ai, fo);
487 PARA_ERROR_LOG("can not create %s socket %s#%d.\n",
488 layer4_name(l4type), host? host : (passive?
489 "[loopback]" : "[localhost]"), port_number);
495 * Create a passive / listening socket.
497 * \param l4type The transport-layer type (\p IPPROTO_xxx).
498 * \param port The decimal port number to listen on.
499 * \param fo Flowopts (if any) to set before starting to listen.
501 * \return Positive integer (socket descriptor) on success, negative value
504 * \sa \ref makesock(), ip(7), ipv6(7), bind(2), listen(2).
506 int para_listen(unsigned l4type, uint16_t port, struct flowopts *fo)
508 int ret, fd = makesock(l4type, 1, NULL, port, fo);
511 ret = listen(fd, BACKLOG);
515 return -ERRNO_TO_PARA_ERROR(ret);
517 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
518 layer4_name(l4type), port, fd);
524 * Determine IPv4/v6 socket address length.
525 * \param sa Container of IPv4 or IPv6 address.
526 * \return Address-family dependent address length.
528 static socklen_t salen(const struct sockaddr *sa)
530 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
532 return sa->sa_family == AF_INET6
533 ? sizeof(struct sockaddr_in6)
534 : sizeof(struct sockaddr_in);
537 /** True if @ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
538 static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
540 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
542 return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
546 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
547 * \param ss Container of IPv4/6 address.
548 * \return Pointer to normalized address (may be static storage).
552 static const struct sockaddr *
553 normalize_ip_address(const struct sockaddr_storage *ss)
555 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
557 if (SS_IS_ADDR_V4MAPPED(ss)) {
558 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
559 static struct sockaddr_in ia;
561 ia.sin_family = AF_INET;
562 ia.sin_port = ia6->sin6_port;
563 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
564 return (const struct sockaddr *)&ia;
566 return (const struct sockaddr *)ss;
570 * Generic/fallback MTU values
572 * These are taken from RFC 1122, RFC 2460, and RFC 5405.
573 * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
574 * to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
575 * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
576 * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
577 * UDP senders should use the respective minimum values of EMTU_S.
579 static inline int generic_mtu(const int af_type)
581 return af_type == AF_INET6 ? 1280 : 576;
584 /** Crude approximation of IP header overhead - neglecting options. */
585 static inline int estimated_header_overhead(const int af_type)
587 return af_type == AF_INET6 ? 40 : 20;
591 * Get the maximum transport-layer message size (MMS_S).
593 * \param sockfd The socket file descriptor.
595 * The socket must be connected. See RFC 1122, 3.3.3. If the protocol family
596 * could not be determined, \p AF_INET is assumed.
598 * \return The maximum message size of the address family type.
600 int generic_max_transport_msg_size(int sockfd)
602 struct sockaddr_storage ss = {.ss_family = 0};
603 socklen_t sslen = sizeof(ss);
604 int af_type = AF_INET;
606 if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
607 PARA_ERROR_LOG("can not determine remote address type: %s\n",
609 } else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
610 af_type = ss.ss_family;
612 return generic_mtu(af_type) - estimated_header_overhead(af_type);
616 * Look up the remote side of a connected socket structure.
618 * \param fd The socket descriptor of the connected socket.
620 * \return A static character string identifying hostname and port of the
621 * chosen side in numeric host:port format.
623 * \sa getsockname(2), getpeername(2), \ref parse_url(), getnameinfo(3),
624 * services(5), nsswitch.conf(5).
626 char *remote_name(int fd)
628 struct sockaddr_storage ss = {.ss_family = 0};
629 const struct sockaddr *sa;
630 socklen_t sslen = sizeof(ss);
631 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
632 static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
635 if (getpeername(fd, (struct sockaddr *)&ss, &sslen) < 0) {
636 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
637 fd, strerror(errno));
638 snprintf(output, sizeof(output), "(unknown)");
641 sa = normalize_ip_address(&ss);
642 ret = getnameinfo(sa, salen(sa), hbuf, sizeof(hbuf), sbuf,
643 sizeof(sbuf), NI_NUMERICHOST | NI_NUMERICSERV);
645 PARA_WARNING_LOG("hostname lookup error (%s).\n",
647 snprintf(output, sizeof(output), "(lookup error)");
648 } else if (sa->sa_family == AF_INET6)
649 snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
651 snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
656 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
658 * \param ss Container of IPv4/6 address.
659 * \param ia Extracted IPv4 address (different from 0) or 0 if unsuccessful.
663 void extract_v4_addr(const struct sockaddr_storage *ss, struct in_addr *ia)
665 const struct sockaddr *sa = normalize_ip_address(ss);
667 memset(ia, 0, sizeof(*ia));
668 if (sa->sa_family == AF_INET)
669 *ia = ((struct sockaddr_in *)sa)->sin_addr;
673 * Compare the address part of IPv4/6 addresses.
675 * \param sa1 First address.
676 * \param sa2 Second address.
678 * \return True iff the IP address of \a sa1 and \a sa2 match.
680 bool sockaddr_equal(const struct sockaddr *sa1, const struct sockaddr *sa2)
684 if (sa1->sa_family != sa2->sa_family)
686 if (sa1->sa_family == AF_INET) {
687 struct sockaddr_in *a1 = (typeof(a1))sa1,
688 *a2 = (typeof (a2))sa2;
689 return a1->sin_addr.s_addr == a2->sin_addr.s_addr;
690 } else if (sa1->sa_family == AF_INET6) {
691 struct sockaddr_in6 *a1 = (typeof(a1))sa1,
692 *a2 = (typeof (a2))sa2;
693 return !memcmp(a1, a2, sizeof(*a1));
699 * Receive data from a file descriptor.
701 * \param fd The file descriptor.
702 * \param buf The buffer to write the data to.
703 * \param size The size of \a buf.
705 * Receive at most \a size bytes from file descriptor \a fd.
707 * \return The number of bytes received on success, negative on errors, zero if
708 * the peer has performed an orderly shutdown.
712 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
716 n = recv(fd, buf, size, 0);
718 return -ERRNO_TO_PARA_ERROR(errno);
723 * Receive and write terminating NULL byte.
725 * \param fd The file descriptor.
726 * \param buf The buffer to write the data to.
727 * \param size The size of \a buf.
729 * Read at most \a size - 1 bytes from file descriptor \a fd and
730 * write a NULL byte at the end of the received data.
732 * \return The return value of the underlying call to \a recv_bin_buffer().
734 * \sa \ref recv_bin_buffer()
736 int recv_buffer(int fd, char *buf, size_t size)
741 n = recv_bin_buffer(fd, buf, size - 1);
750 * Wrapper around the accept system call.
752 * \param fd The listening socket.
753 * \param rfds An optional fd_set pointer.
754 * \param addr Structure which is filled in with the address of the peer socket.
755 * \param size Should contain the size of the structure pointed to by \a addr.
756 * \param new_fd Result pointer.
758 * Accept incoming connections on \a addr, retry if interrupted. If \a rfds is
759 * not \p NULL, return 0 if \a fd is not set in \a rfds without calling accept().
761 * \return Negative on errors, zero if no connections are present to be accepted,
766 int para_accept(int fd, fd_set *rfds, void *addr, socklen_t size, int *new_fd)
770 if (rfds && !FD_ISSET(fd, rfds))
773 ret = accept(fd, (struct sockaddr *) addr, &size);
774 while (ret < 0 && errno == EINTR);
780 if (errno == EAGAIN || errno == EWOULDBLOCK)
782 return -ERRNO_TO_PARA_ERROR(errno);
786 * Probe the list of DCCP CCIDs configured on this host.
787 * \param ccid_array Pointer to return statically allocated array in.
788 * \return Number of elements returned in \a ccid_array or error.
790 * NB: This feature is only available on Linux > 2.6.30; on older kernels
791 * ENOPROTOOPT ("Protocol not available") will be returned.
793 int dccp_available_ccids(uint8_t **ccid_array)
795 static uint8_t ccids[DCCP_MAX_HOST_CCIDS];
796 socklen_t nccids = sizeof(ccids);
799 ret = fd = makesock(IPPROTO_DCCP, 1, NULL, 0, NULL);
803 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
804 ccids, &nccids) < 0) {
807 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
809 return -ERRNO_TO_PARA_ERROR(ret);
818 * Prepare a structure for AF_UNIX socket addresses.
820 * This just copies name to the sun_path component of u, prepending a zero byte
821 * if abstract sockets are supported.
823 * The first call to this function tries to bind a socket to the abstract name
824 * space. The result of this test is stored in a static variable. Subsequent
825 * calls read this variable and create abstract sockets on systems that support
828 static int init_unix_addr(struct sockaddr_un *u, const char *name)
830 static int use_abstract;
832 if (strlen(name) + 1 >= UNIX_PATH_MAX)
833 return -E_NAME_TOO_LONG;
834 memset(u->sun_path, 0, UNIX_PATH_MAX);
835 u->sun_family = PF_UNIX;
836 if (use_abstract == 0) { /* executed only once */
837 int fd = socket(PF_UNIX, SOCK_STREAM, 0);
838 memcpy(u->sun_path, "\0x\0", 3);
839 if (bind(fd, (struct sockaddr *)u, sizeof(*u)) == 0)
840 use_abstract = 1; /* yes */
842 use_abstract = -1; /* no */
844 PARA_NOTICE_LOG("%susing abstract socket namespace\n",
845 use_abstract == 1? "" : "not ");
847 strcpy(u->sun_path + (use_abstract == 1? 1 : 0), name);
852 * Create a socket for local communication and listen on it.
854 * \param name The socket pathname.
856 * This function creates a passive local socket for sequenced, reliable,
857 * two-way, connection-based byte streams. The socket file descriptor is set to
858 * nonblocking mode and listen(2) is called to prepare the socket for
859 * accepting incoming connection requests.
861 * \return The file descriptor on success, negative error code on failure.
863 * \sa socket(2), \sa bind(2), \sa chmod(2), listen(2), unix(7).
865 int create_local_socket(const char *name)
867 struct sockaddr_un unix_addr;
870 ret = init_unix_addr(&unix_addr, name);
873 ret = socket(PF_UNIX, SOCK_STREAM, 0);
875 return -ERRNO_TO_PARA_ERROR(errno);
877 ret = mark_fd_nonblocking(fd);
880 ret = bind(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr));
882 ret = -ERRNO_TO_PARA_ERROR(errno);
885 if (unix_addr.sun_path[0] != 0) { /* pathname socket */
886 mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP
889 if (chmod(name, mode) < 0)
892 if (listen(fd , 5) < 0) {
893 ret = -ERRNO_TO_PARA_ERROR(errno);
903 * Prepare, create, and connect to a Unix domain socket for local communication.
905 * \param name The socket pathname.
907 * This function creates a local socket for sequenced, reliable, two-way,
908 * connection-based byte streams.
910 * \return The file descriptor of the connected socket on success, negative on
913 * \sa \ref create_local_socket(), unix(7), connect(2).
915 int connect_local_socket(const char *name)
917 struct sockaddr_un unix_addr;
920 PARA_DEBUG_LOG("connecting to %s\n", name);
921 fd = socket(PF_UNIX, SOCK_STREAM, 0);
923 return -ERRNO_TO_PARA_ERROR(errno);
924 ret = init_unix_addr(&unix_addr, name);
927 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) != -1)
929 ret = -ERRNO_TO_PARA_ERROR(errno);
936 ssize_t send_cred_buffer(int sock, char *buf)
938 return write_buffer(sock, buf);
940 int recv_cred_buffer(int fd, char *buf, size_t size)
942 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
944 #else /* HAVE_UCRED */
947 * Send a buffer and the credentials of the current process to a socket.
949 * \param sock The file descriptor of the sending socket.
950 * \param buf The zero-terminated buffer to send.
952 * \return On success, this call returns the number of bytes sent. On errors,
953 * \p -E_SENDMSG is returned.
955 * \sa \ref recv_cred_buffer, sendmsg(2), socket(7), unix(7).
957 ssize_t send_cred_buffer(int sock, char *buf)
959 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
961 struct cmsghdr *cmsg;
962 static struct iovec iov;
968 iov.iov_len = strlen(buf);
972 /* compose the message */
973 memset(&msg, 0, sizeof(msg));
976 msg.msg_control = control;
977 msg.msg_controllen = sizeof(control);
978 /* attach the ucred struct */
979 cmsg = CMSG_FIRSTHDR(&msg);
980 cmsg->cmsg_level = SOL_SOCKET;
981 cmsg->cmsg_type = SCM_CREDENTIALS;
982 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
983 *(struct ucred *)CMSG_DATA(cmsg) = c;
984 msg.msg_controllen = cmsg->cmsg_len;
985 ret = sendmsg(sock, &msg, 0);
991 static void dispose_fds(int *fds, unsigned num)
995 for (i = 0; i < num; i++)
1000 * Receive a buffer and the Unix credentials of the sending process.
1002 * \param fd The file descriptor of the receiving socket.
1003 * \param buf The buffer to store the received message.
1004 * \param size The length of \a buf in bytes.
1006 * \return Negative on errors, the user id of the sending process on success.
1008 * \sa \ref send_cred_buffer and the references given there.
1010 int recv_cred_buffer(int fd, char *buf, size_t size)
1012 char control[255] __a_aligned(8);
1014 struct cmsghdr *cmsg;
1020 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
1021 memset(&msg, 0, sizeof(msg));
1022 memset(buf, 0, size);
1027 msg.msg_control = control;
1028 msg.msg_controllen = sizeof(control);
1029 if (recvmsg(fd, &msg, 0) < 0)
1031 result = -E_SCM_CREDENTIALS;
1032 cmsg = CMSG_FIRSTHDR(&msg);
1034 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
1035 == SCM_CREDENTIALS) {
1036 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
1039 if (cmsg->cmsg_level == SOL_SOCKET
1040 && cmsg->cmsg_type == SCM_RIGHTS) {
1041 dispose_fds((int *)CMSG_DATA(cmsg),
1042 (cmsg->cmsg_len - CMSG_LEN(0))
1045 cmsg = CMSG_NXTHDR(&msg, cmsg);
1049 #endif /* HAVE_UCRED */