2 * Copyright (C) 2005-2013 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file net.c Networking-related helper functions. */
10 * Since glibc 2.8, the _GNU_SOURCE feature test macro must be defined in order
11 * to obtain the definition of the ucred structure.
17 /* At least NetBSD needs these. */
25 #define AI_ADDRCONFIG 0
38 * Parse and validate IPv4 address/netmask string.
40 * \param cidr Address in CIDR notation
41 * \param addr Copy of the IPv4 address part of \a cidr
42 * \param addrlen Size of \a addr in bytes
43 * \param netmask Value of the netmask part in \a cidr or the
44 * default of 32 if not specified.
46 * \return Pointer to \a addr if succesful, NULL on error.
49 char *parse_cidr(const char *cidr,
50 char *addr, ssize_t addrlen,
54 char *c = addr, *end = c + (addrlen - 1);
58 if (cidr == NULL || addrlen < 1)
61 for (o = cidr; (*c = *o == '/'? '\0' : *o); c++, o++)
66 if (para_atoi32(++o, netmask) < 0 ||
67 *netmask < 0 || *netmask > 0x20)
70 if (is_valid_ipv4_address(addr))
79 * Match string as a candidate IPv4 address.
81 * \param address The string to match.
82 * \return True if \a address has "dot-quad" format.
84 static bool is_v4_dot_quad(const char *address)
89 assert(para_regcomp(&r, "^([0-9]+\\.){3}[0-9]+$",
90 REG_EXTENDED | REG_NOSUB) >= 0);
91 result = regexec(&r, address, 0, NULL, 0) == 0;
97 * Perform basic syntax checking on the host-part of an URL:
99 * - Since ':' is invalid in IPv4 addresses and DNS names, the
100 * presence of ':' causes interpretation as IPv6 address;
101 * - next the first-match-wins algorithm from RFC 3986 is applied;
102 * - else the string is considered as DNS name, to be resolved later.
104 * \param host The host string to check.
105 * \return True if \a host passes the syntax checks.
107 * \sa RFC 3986, 3.2.2; RFC 1123, 2.1; RFC 1034, 3.5
109 static bool host_string_ok(const char *host)
111 if (host == NULL || *host == '\0')
113 if (strchr(host, ':') != NULL)
114 return is_valid_ipv6_address(host);
115 if (is_v4_dot_quad(host))
116 return is_valid_ipv4_address(host);
121 * Parse and validate URL string.
123 * The URL syntax is loosely based on RFC 3986, supporting one of
124 * - "["host"]"[:port] for native IPv6 addresses and
125 * - host[:port] for IPv4 hostnames and DNS names.
127 * Native IPv6 addresses must be enclosed in square brackets, since
128 * otherwise there is an ambiguity with the port separator `:'.
129 * The 'port' part is always considered to be a number; if absent,
130 * it is set to -1, to indicate that a default port is to be used.
132 * The following are valid examples:
140 * \param url The URL string to take apart.
141 * \param host To return the copied host part of \a url.
142 * \param hostlen The maximum length of \a host.
143 * \param port To return the port number (if any) of \a url.
145 * \return Pointer to \a host, or \p NULL if failed. If \p NULL is returned,
146 * \a host and \a port are undefined. If no port number was present in \a url,
147 * \a port is set to -1.
149 * \sa RFC 3986, 3.2.2/3.2.3
151 char *parse_url(const char *url,
152 char *host, ssize_t hostlen,
156 char *c = host, *end = c + (hostlen - 1);
160 if (o == NULL || hostlen < 1)
164 for (++o; (*c = *o == ']' ? '\0' : *o); c++, o++)
168 if (*o++ != ']' || (*o != '\0' && *o != ':'))
171 for (; (*c = *o == ':'? '\0' : *o); c++, o++) {
172 if (c == end && o[1])
178 if (para_atoi32(++o, port) < 0 ||
179 *port < 0 || *port > 0xffff)
181 if (host_string_ok(host))
189 * Stringify port number, resolve into service name where defined.
190 * \param port 2-byte port number, in host-byte-order.
191 * \param transport Transport protocol name (e.g. "udp", "tcp"), or NULL.
192 * \return Pointer to static result buffer.
194 * \sa getservent(3), services(5), nsswitch.conf(5)
196 const char *stringify_port(int port, const char *transport)
198 static char service[NI_MAXSERV];
200 if (port < 0 || port > 0xFFFF) {
201 snprintf(service, sizeof(service), "undefined (%d)", port);
203 struct servent *se = getservbyport(htons(port), transport);
206 snprintf(service, sizeof(service), "%u", port);
208 snprintf(service, sizeof(service), "%s", se->s_name);
214 * Determine the socket type for a given layer-4 protocol.
216 * \param l4type The symbolic name of the transport-layer protocol.
218 * \sa ip(7), socket(2)
220 static inline int sock_type(const unsigned l4type)
223 case IPPROTO_UDP: return SOCK_DGRAM;
224 case IPPROTO_TCP: return SOCK_STREAM;
225 case IPPROTO_DCCP: return SOCK_DCCP;
227 return -1; /* not supported here */
231 * Pretty-print transport-layer name.
233 static const char *layer4_name(const unsigned l4type)
236 case IPPROTO_UDP: return "UDP";
237 case IPPROTO_TCP: return "TCP";
238 case IPPROTO_DCCP: return "DCCP";
240 return "UNKNOWN PROTOCOL";
244 * Flowopts: Transport-layer independent encapsulation of socket options.
246 * These collect individual socket options into a queue, which is disposed of
247 * directly after makesock(). The 'pre_conn_opt' structure is for internal use
248 * only and should not be visible elsewhere.
250 * \sa setsockopt(2), makesock()
252 struct pre_conn_opt {
253 int sock_level; /**< Second argument to setsockopt() */
254 int sock_option; /**< Third argument to setsockopt() */
255 char *opt_name; /**< Stringified \a sock_option */
256 void *opt_val; /**< Fourth argument to setsockopt() */
257 socklen_t opt_len; /**< Fifth argument to setsockopt() */
259 struct list_head node; /**< FIFO, as sockopt order matters. */
262 /** FIFO list of pre-connection socket options to be set */
264 struct list_head sockopts;
268 * Allocate and initialize a flowopt queue.
270 * \return A new structure to be passed to \ref flowopt_add(). It is
271 * automatically deallocated in \ref makesock().
273 struct flowopts *flowopt_new(void)
275 struct flowopts *new = para_malloc(sizeof(*new));
277 INIT_LIST_HEAD(&new->sockopts);
282 * Append new socket option to flowopt queue.
284 * \param fo The flowopt queue to append to.
285 * \param lev Level at which \a opt resides.
286 * \param opt New option to add.
287 * \param name Stringified name of \a opt.
288 * \param val The value to set \a opt to.
289 * \param len Length of \a val.
293 void flowopt_add(struct flowopts *fo, int lev, int opt,
294 const char *name, const void *val, int len)
296 struct pre_conn_opt *new = para_malloc(sizeof(*new));
298 new->sock_option = opt;
299 new->sock_level = lev;
300 new->opt_name = para_strdup(name);
306 new->opt_val = para_malloc(len);
308 memcpy(new->opt_val, val, len);
311 list_add_tail(&new->node, &fo->sockopts);
314 /** Set the entire bunch of pre-connection options at once. */
315 static void flowopt_setopts(int sockfd, struct flowopts *fo)
317 struct pre_conn_opt *pc;
322 list_for_each_entry(pc, &fo->sockopts, node)
323 if (setsockopt(sockfd, pc->sock_level, pc->sock_option,
324 pc->opt_val, pc->opt_len) < 0) {
325 PARA_EMERG_LOG("Can not set %s socket option: %s",
326 pc->opt_name, strerror(errno));
331 static void flowopt_cleanup(struct flowopts *fo)
333 struct pre_conn_opt *cur, *next;
338 list_for_each_entry_safe(cur, next, &fo->sockopts, node) {
347 * Resolve an IPv4/IPv6 address.
349 * \param l4type The layer-4 type (\p IPPROTO_xxx).
350 * \param passive Whether \p AI_PASSIVE should be included as hint.
351 * \param host Remote or local hostname or IPv/6 address string.
352 * \param port_number Used to set the port in each returned address structure.
353 * \param result addrinfo structures are returned here.
355 * The interpretation of \a host depends on the value of \a passive. On a
356 * passive socket host is interpreted as an interface IPv4/6 address (can be
357 * left NULL). On an active socket, \a host is the peer DNS name or IPv4/6
358 * address to connect to.
362 * \sa getaddrinfo(3).
364 static int lookup_address(unsigned l4type, bool passive, const char *host,
365 int port_number, struct addrinfo **result)
368 char port[6]; /* port number has at most 5 digits */
369 struct addrinfo *addr = NULL, hints;
372 sprintf(port, "%u", port_number & 0xffff);
373 /* Set up address hint structure */
374 memset(&hints, 0, sizeof(hints));
375 hints.ai_family = AF_UNSPEC;
376 hints.ai_socktype = sock_type(l4type);
378 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
379 * (and only then) pretend to be UDP.
381 if (l4type == IPPROTO_DCCP)
382 hints.ai_socktype = SOCK_DGRAM;
383 /* only use addresses available on the host */
384 hints.ai_flags = AI_ADDRCONFIG;
385 if (passive && host == NULL)
386 hints.ai_flags |= AI_PASSIVE;
387 /* Obtain local/remote address information */
388 ret = getaddrinfo(host, port, &hints, &addr);
390 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s\n",
392 host? host : (passive? "[loopback]" : "[localhost]"),
393 port, gai_strerror(ret));
394 return -E_ADDRESS_LOOKUP;
401 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
403 * \param l4type The layer-4 type (\p IPPROTO_xxx).
404 * \param passive Whether this is a passive or active socket.
405 * \param host Passed to \ref \a lookup_address().
406 * \param port_number Passed to \ref \a lookup_address().
407 * \param fo Socket options to be set before making the connection.
409 * This creates a ready-made IPv4/v6 socket structure after looking up the
410 * necessary parameters.
412 * bind(2) is called on passive sockets, and connect(2) on active sockets. The
413 * algorithm tries all possible address combinations until it succeeds. If \a
414 * fo is supplied, options are set and cleanup is performed.
418 * \sa \ref lookup_address(), ipv6(7), getaddrinfo(3), bind(2), connect(2).
420 int makesock(unsigned l4type, bool passive,
421 const char *host, uint16_t port_number,
424 struct addrinfo *local = NULL, *src = NULL, *remote = NULL, *dst = NULL;
425 int rc, on = 1, sockfd = -1;
427 rc = lookup_address(l4type, passive, host, port_number, passive?
431 /* Iterate over all src/dst combination, exhausting dst first */
432 for (src = local, dst = remote; src != NULL || dst != NULL; /* no op */ ) {
433 if (src && dst && src->ai_family == AF_INET
434 && dst->ai_family == AF_INET6)
435 goto get_next_dst; /* v4 -> v6 is not possible */
437 sockfd = socket(src ? src->ai_family : dst->ai_family,
438 sock_type(l4type), l4type);
443 * Reuse the address on passive sockets to avoid failure on
444 * restart (protocols using listen()) and when creating
445 * multiple listener instances (UDP multicast).
447 if (passive && setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
448 &on, sizeof(on)) == -1) {
451 PARA_ERROR_LOG("can not set SO_REUSEADDR: %s\n",
453 rc = -ERRNO_TO_PARA_ERROR(rc);
456 flowopt_setopts(sockfd, fo);
459 if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
463 if (!dst) /* bind-only completed successfully */
467 if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
468 break; /* connection completed successfully */
471 if (dst && (dst = dst->ai_next))
474 if (src && (src = src->ai_next)) /* restart inner loop */
481 freeaddrinfo(remote);
484 if (src == NULL && dst == NULL) {
487 PARA_ERROR_LOG("can not create %s socket %s#%d.\n",
488 layer4_name(l4type), host? host : (passive?
489 "[loopback]" : "[localhost]"), port_number);
496 * Create a passive / listening socket.
498 * \param l4type The transport-layer type (\p IPPROTO_xxx).
499 * \param port The decimal port number to listen on.
500 * \param fo Flowopts (if any) to set before starting to listen.
502 * \return Positive integer (socket descriptor) on success, negative value
505 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
507 int para_listen(unsigned l4type, uint16_t port, struct flowopts *fo)
509 int ret, fd = makesock(l4type, 1, NULL, port, fo);
512 ret = listen(fd, BACKLOG);
516 return -ERRNO_TO_PARA_ERROR(ret);
518 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
519 layer4_name(l4type), port, fd);
525 * Determine IPv4/v6 socket address length.
526 * \param sa Container of IPv4 or IPv6 address.
527 * \return Address-family dependent address length.
529 static socklen_t salen(const struct sockaddr *sa)
531 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
533 return sa->sa_family == AF_INET6
534 ? sizeof(struct sockaddr_in6)
535 : sizeof(struct sockaddr_in);
538 /** True if @ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
539 static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
541 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
543 return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
547 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
548 * \param ss Container of IPv4/6 address.
549 * \return Pointer to normalized address (may be static storage).
553 static const struct sockaddr *
554 normalize_ip_address(const struct sockaddr_storage *ss)
556 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
558 if (SS_IS_ADDR_V4MAPPED(ss)) {
559 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
560 static struct sockaddr_in ia;
562 ia.sin_family = AF_INET;
563 ia.sin_port = ia6->sin6_port;
564 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
565 return (const struct sockaddr *)&ia;
567 return (const struct sockaddr *)ss;
571 * Generic/fallback MTU values
573 * These are taken from RFC 1122, RFC 2460, and RFC 5405.
574 * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
575 * to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
576 * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
577 * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
578 * UDP senders should use the respective minimum values of EMTU_S.
580 static inline int generic_mtu(const int af_type)
582 return af_type == AF_INET6 ? 1280 : 576;
585 /** Crude approximation of IP header overhead - neglecting options. */
586 static inline int estimated_header_overhead(const int af_type)
588 return af_type == AF_INET6 ? 40 : 20;
592 * Get the maximum transport-layer message size (MMS_S).
594 * \param sockfd The socket file descriptor.
596 * The socket must be connected. See RFC 1122, 3.3.3. If the protocol familiy
597 * could not be determined, \p AF_INET is assumed.
599 * \return The maximum message size of the address family type.
601 int generic_max_transport_msg_size(int sockfd)
603 struct sockaddr_storage ss;
604 socklen_t sslen = sizeof(ss);
605 int af_type = AF_INET;
607 if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
608 PARA_ERROR_LOG("can not determine remote address type: %s\n",
610 } else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
611 af_type = ss.ss_family;
613 return generic_mtu(af_type) - estimated_header_overhead(af_type);
617 * Look up the local or remote side of a connected socket structure.
619 * \param fd The socket descriptor of the connected socket.
620 * \param getname Either \p getsockname() for local, or \p getpeername() for
623 * \return A static character string identifying hostname and port of the
624 * chosen side in numeric host:port format.
626 * \sa getsockname(2), getpeername(2), parse_url(), getnameinfo(3),
627 * services(5), nsswitch.conf(5).
629 static char *__get_sock_name(int fd, typeof(getsockname) getname)
631 struct sockaddr_storage ss;
632 const struct sockaddr *sa;
633 socklen_t sslen = sizeof(ss);
634 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
635 static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
638 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
639 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
640 fd, strerror(errno));
641 snprintf(output, sizeof(output), "(unknown)");
644 sa = normalize_ip_address(&ss);
645 ret = getnameinfo(sa, salen(sa), hbuf, sizeof(hbuf), sbuf,
646 sizeof(sbuf), NI_NUMERICHOST | NI_NUMERICSERV);
648 PARA_WARNING_LOG("hostname lookup error (%s).\n",
650 snprintf(output, sizeof(output), "(lookup error)");
651 } else if (sa->sa_family == AF_INET6)
652 snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
654 snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
659 * Look up the local side of a connected socket structure.
661 * \param sockfd The file descriptor of the socket.
663 * \return A pointer to a static buffer containing hostname an port. This
664 * buffer must not be freed by the caller.
668 char *local_name(int sockfd)
670 return __get_sock_name(sockfd, getsockname);
674 * Look up the remote side of a connected socket structure.
676 * \param sockfd The file descriptor of the socket.
678 * \return Analogous to the return value of \ref local_name() but for the
683 char *remote_name(int sockfd)
685 return __get_sock_name(sockfd, getpeername);
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 * Receive data from a file descriptor.
708 * \param fd The file descriptor.
709 * \param buf The buffer to write the data to.
710 * \param size The size of \a buf.
712 * Receive at most \a size bytes from file descriptor \a fd.
714 * \return The number of bytes received on success, negative on errors, zero if
715 * the peer has performed an orderly shutdown.
719 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
723 n = recv(fd, buf, size, 0);
725 return -ERRNO_TO_PARA_ERROR(errno);
730 * Receive and write terminating NULL byte.
732 * \param fd The file descriptor.
733 * \param buf The buffer to write the data to.
734 * \param size The size of \a buf.
736 * Read at most \a size - 1 bytes from file descriptor \a fd and
737 * write a NULL byte at the end of the received data.
739 * \return The return value of the underlying call to \a recv_bin_buffer().
741 * \sa recv_bin_buffer()
743 int recv_buffer(int fd, char *buf, size_t size)
748 n = recv_bin_buffer(fd, buf, size - 1);
757 * Wrapper around the accept system call.
759 * \param fd The listening socket.
760 * \param rfds An optional fd_set pointer.
761 * \param addr Structure which is filled in with the address of the peer socket.
762 * \param size Should contain the size of the structure pointed to by \a addr.
763 * \param new_fd Result pointer.
765 * Accept incoming connections on \a addr, retry if interrupted. If \a rfds is
766 * not \p NULL, return 0 if \a fd is not set in \a rfds without calling accept().
768 * \return Negative on errors, zero if no connections are present to be accepted,
773 int para_accept(int fd, fd_set *rfds, void *addr, socklen_t size, int *new_fd)
777 if (rfds && !FD_ISSET(fd, rfds))
780 ret = accept(fd, (struct sockaddr *) addr, &size);
781 while (ret < 0 && errno == EINTR);
787 if (errno == EAGAIN || errno == EWOULDBLOCK)
789 return -ERRNO_TO_PARA_ERROR(errno);
793 * Probe the list of DCCP CCIDs configured on this host.
794 * \param ccid_array Pointer to return statically allocated array in.
795 * \return Number of elements returned in \a ccid_array or error.
797 * NB: This feature is only available on Linux > 2.6.30; on older kernels
798 * ENOPROTOOPT ("Protocol not available") will be returned.
800 int dccp_available_ccids(uint8_t **ccid_array)
802 static uint8_t ccids[DCCP_MAX_HOST_CCIDS];
803 socklen_t nccids = sizeof(ccids);
806 ret = fd = makesock(IPPROTO_DCCP, 1, NULL, 0, NULL);
810 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
811 ccids, &nccids) < 0) {
814 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
816 return -ERRNO_TO_PARA_ERROR(ret);
825 * Prepare a structure for \p AF_UNIX socket addresses.
827 * \param u Pointer to the struct to be prepared.
828 * \param name The socket pathname.
830 * This just copies \a name to the sun_path component of \a u.
832 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
833 * than \p UNIX_PATH_MAX.
835 static int init_unix_addr(struct sockaddr_un *u, const char *name)
837 if (strlen(name) >= UNIX_PATH_MAX)
838 return -E_NAME_TOO_LONG;
839 memset(u->sun_path, 0, UNIX_PATH_MAX);
840 u->sun_family = PF_UNIX;
841 strcpy(u->sun_path, name);
846 * Prepare, create, and bind a socket for local communication.
848 * \param name The socket pathname.
849 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
850 * \param mode The desired mode of the socket.
852 * This function creates a local socket for sequenced, reliable,
853 * two-way, connection-based byte streams.
855 * \return The file descriptor, on success, negative on errors.
861 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
866 ret = init_unix_addr(unix_addr, name);
869 ret = socket(PF_UNIX, SOCK_STREAM, 0);
871 return -ERRNO_TO_PARA_ERROR(errno);
873 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
875 ret = -ERRNO_TO_PARA_ERROR(errno);
879 if (chmod(name, mode) < 0)
888 * Prepare, create, and connect to a Unix domain socket for local communication.
890 * \param name The socket pathname.
892 * This function creates a local socket for sequenced, reliable, two-way,
893 * connection-based byte streams.
895 * \return The file descriptor of the connected socket on success, negative on
898 * \sa create_local_socket(), unix(7), connect(2).
900 int connect_local_socket(const char *name)
902 struct sockaddr_un unix_addr;
905 PARA_DEBUG_LOG("connecting to %s\n", name);
906 ret = init_unix_addr(&unix_addr, name);
909 fd = socket(PF_UNIX, SOCK_STREAM, 0);
911 return -ERRNO_TO_PARA_ERROR(errno);
912 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) == -1) {
913 ret = -ERRNO_TO_PARA_ERROR(errno);
923 ssize_t send_cred_buffer(int sock, char *buf)
925 return write_buffer(sock, buf);
927 int recv_cred_buffer(int fd, char *buf, size_t size)
929 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
931 #else /* HAVE_UCRED */
933 * Send \p NULL-terminated buffer and Unix credentials of the current process.
935 * \param sock The socket file descriptor.
936 * \param buf The buffer to be sent.
938 * \return On success, this call returns the number of characters sent. On
939 * error, \p -E_SENDMSG is returned.
941 * \sa sendmsg(2), okir's Black Hats Manual.
943 ssize_t send_cred_buffer(int sock, char *buf)
945 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
947 struct cmsghdr *cmsg;
948 static struct iovec iov;
954 iov.iov_len = strlen(buf);
958 /* compose the message */
959 memset(&msg, 0, sizeof(msg));
962 msg.msg_control = control;
963 msg.msg_controllen = sizeof(control);
964 /* attach the ucred struct */
965 cmsg = CMSG_FIRSTHDR(&msg);
966 cmsg->cmsg_level = SOL_SOCKET;
967 cmsg->cmsg_type = SCM_CREDENTIALS;
968 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
969 *(struct ucred *)CMSG_DATA(cmsg) = c;
970 msg.msg_controllen = cmsg->cmsg_len;
971 ret = sendmsg(sock, &msg, 0);
977 static void dispose_fds(int *fds, unsigned num)
981 for (i = 0; i < num; i++)
986 * Receive a buffer and the Unix credentials of the sending process.
988 * \param fd the socket file descriptor.
989 * \param buf the buffer to store the message.
990 * \param size the size of \a buffer.
992 * \return negative on errors, the user id on success.
994 * \sa recvmsg(2), okir's Black Hats Manual.
996 int recv_cred_buffer(int fd, char *buf, size_t size)
1000 struct cmsghdr *cmsg;
1006 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
1007 memset(&msg, 0, sizeof(msg));
1008 memset(buf, 0, size);
1013 msg.msg_control = control;
1014 msg.msg_controllen = sizeof(control);
1015 if (recvmsg(fd, &msg, 0) < 0)
1017 result = -E_SCM_CREDENTIALS;
1018 cmsg = CMSG_FIRSTHDR(&msg);
1020 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
1021 == SCM_CREDENTIALS) {
1022 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
1025 if (cmsg->cmsg_level == SOL_SOCKET
1026 && cmsg->cmsg_type == SCM_RIGHTS) {
1027 dispose_fds((int *) CMSG_DATA(cmsg),
1028 (cmsg->cmsg_len - CMSG_LEN(0))
1031 cmsg = CMSG_NXTHDR(&msg, cmsg);
1035 #endif /* HAVE_UCRED */