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.
15 #include <netinet/in.h>
16 #include <arpa/inet.h>
18 #include <sys/types.h>
19 #include <sys/socket.h>
22 /* At least NetBSD needs these. */
30 #define AI_ADDRCONFIG 0
43 * Parse and validate IPv4 address/netmask string.
45 * \param cidr Address in CIDR notation
46 * \param addr Copy of the IPv4 address part of \a cidr
47 * \param addrlen Size of \a addr in bytes
48 * \param netmask Value of the netmask part in \a cidr or the
49 * default of 32 if not specified.
51 * \return Pointer to \a addr if succesful, NULL on error.
54 char *parse_cidr(const char *cidr,
55 char *addr, ssize_t addrlen,
59 char *c = addr, *end = c + (addrlen - 1);
63 if (cidr == NULL || addrlen < 1)
66 for (o = cidr; (*c = *o == '/'? '\0' : *o); c++, o++)
71 if (para_atoi32(++o, netmask) < 0 ||
72 *netmask < 0 || *netmask > 0x20)
75 if (is_valid_ipv4_address(addr))
84 * Match string as a candidate IPv4 address.
86 * \param address The string to match.
87 * \return True if \a address has "dot-quad" format.
89 static bool is_v4_dot_quad(const char *address)
94 assert(para_regcomp(&r, "^([0-9]+\\.){3}[0-9]+$",
95 REG_EXTENDED | REG_NOSUB) >= 0);
96 result = regexec(&r, address, 0, NULL, 0) == 0;
102 * Perform basic syntax checking on the host-part of an URL:
104 * - Since ':' is invalid in IPv4 addresses and DNS names, the
105 * presence of ':' causes interpretation as IPv6 address;
106 * - next the first-match-wins algorithm from RFC 3986 is applied;
107 * - else the string is considered as DNS name, to be resolved later.
109 * \param host The host string to check.
110 * \return True if \a host passes the syntax checks.
112 * \sa RFC 3986, 3.2.2; RFC 1123, 2.1; RFC 1034, 3.5
114 static bool host_string_ok(const char *host)
116 if (host == NULL || *host == '\0')
118 if (strchr(host, ':') != NULL)
119 return is_valid_ipv6_address(host);
120 if (is_v4_dot_quad(host))
121 return is_valid_ipv4_address(host);
126 * Parse and validate URL string.
128 * The URL syntax is loosely based on RFC 3986, supporting one of
129 * - "["host"]"[:port] for native IPv6 addresses and
130 * - host[:port] for IPv4 hostnames and DNS names.
132 * Native IPv6 addresses must be enclosed in square brackets, since
133 * otherwise there is an ambiguity with the port separator `:'.
134 * The 'port' part is always considered to be a number; if absent,
135 * it is set to -1, to indicate that a default port is to be used.
137 * The following are valid examples:
145 * \param url The URL string to take apart.
146 * \param host To return the copied host part of \a url.
147 * \param hostlen The maximum length of \a host.
148 * \param port To return the port number (if any) of \a url.
150 * \return Pointer to \a host, or \p NULL if failed. If \p NULL is returned,
151 * \a host and \a port are undefined. If no port number was present in \a url,
152 * \a port is set to -1.
154 * \sa RFC 3986, 3.2.2/3.2.3
156 char *parse_url(const char *url,
157 char *host, ssize_t hostlen,
161 char *c = host, *end = c + (hostlen - 1);
165 if (o == NULL || hostlen < 1)
169 for (++o; (*c = *o == ']' ? '\0' : *o); c++, o++)
173 if (*o++ != ']' || (*o != '\0' && *o != ':'))
176 for (; (*c = *o == ':'? '\0' : *o); c++, o++) {
177 if (c == end && o[1])
183 if (para_atoi32(++o, port) < 0 ||
184 *port < 0 || *port > 0xffff)
186 if (host_string_ok(host))
194 * Stringify port number, resolve into service name where defined.
195 * \param port 2-byte port number, in host-byte-order.
196 * \param transport Transport protocol name (e.g. "udp", "tcp"), or NULL.
197 * \return Pointer to static result buffer.
199 * \sa getservent(3), services(5), nsswitch.conf(5)
201 const char *stringify_port(int port, const char *transport)
203 static char service[NI_MAXSERV];
205 if (port < 0 || port > 0xFFFF) {
206 snprintf(service, sizeof(service), "undefined (%d)", port);
208 struct servent *se = getservbyport(htons(port), transport);
211 snprintf(service, sizeof(service), "%u", port);
213 snprintf(service, sizeof(service), "%s", se->s_name);
219 * Determine the socket type for a given layer-4 protocol.
221 * \param l4type The symbolic name of the transport-layer protocol.
223 * \sa ip(7), socket(2)
225 static inline int sock_type(const unsigned l4type)
228 case IPPROTO_UDP: return SOCK_DGRAM;
229 case IPPROTO_TCP: return SOCK_STREAM;
230 case IPPROTO_DCCP: return SOCK_DCCP;
232 return -1; /* not supported here */
236 * Pretty-print transport-layer name.
238 static const char *layer4_name(const unsigned l4type)
241 case IPPROTO_UDP: return "UDP";
242 case IPPROTO_TCP: return "TCP";
243 case IPPROTO_DCCP: return "DCCP";
245 return "UNKNOWN PROTOCOL";
249 * Flowopts: Transport-layer independent encapsulation of socket options.
251 * These collect individual socket options into a queue, which is disposed of
252 * directly after makesock(). The 'pre_conn_opt' structure is for internal use
253 * only and should not be visible elsewhere.
255 * \sa setsockopt(2), makesock()
257 struct pre_conn_opt {
258 int sock_level; /**< Second argument to setsockopt() */
259 int sock_option; /**< Third argument to setsockopt() */
260 char *opt_name; /**< Stringified \a sock_option */
261 void *opt_val; /**< Fourth argument to setsockopt() */
262 socklen_t opt_len; /**< Fifth argument to setsockopt() */
264 struct list_head node; /**< FIFO, as sockopt order matters. */
267 /** FIFO list of pre-connection socket options to be set */
269 struct list_head sockopts;
273 * Allocate and initialize a flowopt queue.
275 * \return A new structure to be passed to \ref flowopt_add(). It is
276 * automatically deallocated in \ref makesock().
278 struct flowopts *flowopt_new(void)
280 struct flowopts *new = para_malloc(sizeof(*new));
282 INIT_LIST_HEAD(&new->sockopts);
287 * Append new socket option to flowopt queue.
289 * \param fo The flowopt queue to append to.
290 * \param lev Level at which \a opt resides.
291 * \param opt New option to add.
292 * \param name Stringified name of \a opt.
293 * \param val The value to set \a opt to.
294 * \param len Length of \a val.
298 void flowopt_add(struct flowopts *fo, int lev, int opt,
299 const char *name, const void *val, int len)
301 struct pre_conn_opt *new = para_malloc(sizeof(*new));
303 new->sock_option = opt;
304 new->sock_level = lev;
305 new->opt_name = para_strdup(name);
311 new->opt_val = para_malloc(len);
313 memcpy(new->opt_val, val, len);
316 list_add_tail(&new->node, &fo->sockopts);
319 /** Set the entire bunch of pre-connection options at once. */
320 static void flowopt_setopts(int sockfd, struct flowopts *fo)
322 struct pre_conn_opt *pc;
327 list_for_each_entry(pc, &fo->sockopts, node)
328 if (setsockopt(sockfd, pc->sock_level, pc->sock_option,
329 pc->opt_val, pc->opt_len) < 0) {
330 PARA_EMERG_LOG("Can not set %s socket option: %s",
331 pc->opt_name, strerror(errno));
336 static void flowopt_cleanup(struct flowopts *fo)
338 struct pre_conn_opt *cur, *next;
343 list_for_each_entry_safe(cur, next, &fo->sockopts, node) {
352 * Resolve an IPv4/IPv6 address.
354 * \param l4type The layer-4 type (\p IPPROTO_xxx).
355 * \param passive Whether \p AI_PASSIVE should be included as hint.
356 * \param host Remote or local hostname or IPv/6 address string.
357 * \param port_number Used to set the port in each returned address structure.
358 * \param result addrinfo structures are returned here.
360 * The interpretation of \a host depends on the value of \a passive. On a
361 * passive socket host is interpreted as an interface IPv4/6 address (can be
362 * left NULL). On an active socket, \a host is the peer DNS name or IPv4/6
363 * address to connect to.
367 * \sa getaddrinfo(3).
369 static int lookup_address(unsigned l4type, bool passive, const char *host,
370 int port_number, struct addrinfo **result)
373 char port[6]; /* port number has at most 5 digits */
374 struct addrinfo *addr = NULL, hints;
377 sprintf(port, "%u", port_number & 0xffff);
378 /* Set up address hint structure */
379 memset(&hints, 0, sizeof(hints));
380 hints.ai_family = AF_UNSPEC;
381 hints.ai_socktype = sock_type(l4type);
383 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
384 * (and only then) pretend to be UDP.
386 if (l4type == IPPROTO_DCCP)
387 hints.ai_socktype = SOCK_DGRAM;
388 /* only use addresses available on the host */
389 hints.ai_flags = AI_ADDRCONFIG;
390 if (passive && host == NULL)
391 hints.ai_flags |= AI_PASSIVE;
392 /* Obtain local/remote address information */
393 ret = getaddrinfo(host, port, &hints, &addr);
395 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s\n",
397 host? host : (passive? "[loopback]" : "[localhost]"),
398 port, gai_strerror(ret));
399 return -E_ADDRESS_LOOKUP;
406 * Create an active or passive socket.
408 * \param l4type \p IPPROTO_TCP, \p IPPROTO_UDP, or \p IPPROTO_DCCP.
409 * \param passive Whether to call bind(2) or connect(2).
410 * \param ai Address information as obtained from \ref lookup_address().
411 * \param fo Socket options to be set before making the connection.
413 * bind(2) is called on passive sockets, and connect(2) on active sockets. The
414 * algorithm tries all possible address combinations until it succeeds. If \a
415 * fo is supplied, options are set and cleanup is performed.
417 * \return File descriptor on success, \p E_MAKESOCK on errors.
419 * \sa \ref lookup_address(), \ref makesock(), ip(7), ipv6(7), bind(2),
422 static int makesock_addrinfo(unsigned l4type, bool passive, struct addrinfo *ai,
425 int ret = -E_MAKESOCK, on = 1, sockfd = -1;
427 for (; ai; ai = ai->ai_next) {
428 ret = socket(ai->ai_family, sock_type(l4type), l4type);
432 flowopt_setopts(sockfd, fo);
434 if (connect(sockfd, ai->ai_addr, ai->ai_addrlen) == 0)
440 * Reuse the address on passive sockets to avoid failure on
441 * restart (protocols using listen()) and when creating
442 * multiple listener instances (UDP multicast).
444 if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on,
449 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
459 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
461 * \param l4type The layer-4 type (\p IPPROTO_xxx).
462 * \param passive Whether this is a passive or active socket.
463 * \param host Passed to \ref lookup_address().
464 * \param port_number Passed to \ref lookup_address().
465 * \param fo Passed to \ref makesock_addrinfo().
467 * This creates a ready-made IPv4/v6 socket structure after looking up the
468 * necessary parameters. The function first calls \ref lookup_address() and
469 * passes the address information to makesock_addrinfo() to create and
470 * initialize the socket.
472 * \return The newly created file descriptor on success, a negative error code
475 * \sa \ref lookup_address(), \ref makesock_addrinfo().
477 int makesock(unsigned l4type, bool passive, const char *host, uint16_t port_number,
481 int ret = lookup_address(l4type, passive, host, port_number, &ai);
484 ret = makesock_addrinfo(l4type, passive, ai, fo);
489 PARA_ERROR_LOG("can not create %s socket %s#%d.\n",
490 layer4_name(l4type), host? host : (passive?
491 "[loopback]" : "[localhost]"), port_number);
497 * Create a passive / listening socket.
499 * \param l4type The transport-layer type (\p IPPROTO_xxx).
500 * \param port The decimal port number to listen on.
501 * \param fo Flowopts (if any) to set before starting to listen.
503 * \return Positive integer (socket descriptor) on success, negative value
506 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
508 int para_listen(unsigned l4type, uint16_t port, struct flowopts *fo)
510 int ret, fd = makesock(l4type, 1, NULL, port, fo);
513 ret = listen(fd, BACKLOG);
517 return -ERRNO_TO_PARA_ERROR(ret);
519 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
520 layer4_name(l4type), port, fd);
526 * Determine IPv4/v6 socket address length.
527 * \param sa Container of IPv4 or IPv6 address.
528 * \return Address-family dependent address length.
530 static socklen_t salen(const struct sockaddr *sa)
532 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
534 return sa->sa_family == AF_INET6
535 ? sizeof(struct sockaddr_in6)
536 : sizeof(struct sockaddr_in);
539 /** True if @ss holds a v6-mapped-v4 address (RFC 4291, 2.5.5.2) */
540 static bool SS_IS_ADDR_V4MAPPED(const struct sockaddr_storage *ss)
542 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
544 return ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr);
548 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
549 * \param ss Container of IPv4/6 address.
550 * \return Pointer to normalized address (may be static storage).
554 static const struct sockaddr *
555 normalize_ip_address(const struct sockaddr_storage *ss)
557 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
559 if (SS_IS_ADDR_V4MAPPED(ss)) {
560 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
561 static struct sockaddr_in ia;
563 ia.sin_family = AF_INET;
564 ia.sin_port = ia6->sin6_port;
565 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
566 return (const struct sockaddr *)&ia;
568 return (const struct sockaddr *)ss;
572 * Generic/fallback MTU values
574 * These are taken from RFC 1122, RFC 2460, and RFC 5405.
575 * - RFC 1122, 3.3.3 defines EMTU_S ("Effective MTU for sending") and recommends
576 * to use an EMTU_S size of of 576 bytes if the IPv4 path MTU is unknown;
577 * - RFC 2460, 5. requires a minimum IPv6 MTU of 1280 bytes;
578 * - RFC 5405, 3.2 recommends that if path MTU discovery is not done,
579 * UDP senders should use the respective minimum values of EMTU_S.
581 static inline int generic_mtu(const int af_type)
583 return af_type == AF_INET6 ? 1280 : 576;
586 /** Crude approximation of IP header overhead - neglecting options. */
587 static inline int estimated_header_overhead(const int af_type)
589 return af_type == AF_INET6 ? 40 : 20;
593 * Get the maximum transport-layer message size (MMS_S).
595 * \param sockfd The socket file descriptor.
597 * The socket must be connected. See RFC 1122, 3.3.3. If the protocol familiy
598 * could not be determined, \p AF_INET is assumed.
600 * \return The maximum message size of the address family type.
602 int generic_max_transport_msg_size(int sockfd)
604 struct sockaddr_storage ss;
605 socklen_t sslen = sizeof(ss);
606 int af_type = AF_INET;
608 if (getpeername(sockfd, (struct sockaddr *)&ss, &sslen) < 0) {
609 PARA_ERROR_LOG("can not determine remote address type: %s\n",
611 } else if (!SS_IS_ADDR_V4MAPPED(&ss)) {
612 af_type = ss.ss_family;
614 return generic_mtu(af_type) - estimated_header_overhead(af_type);
618 * Look up the local or remote side of a connected socket structure.
620 * \param fd The socket descriptor of the connected socket.
621 * \param getname Either \p getsockname() for local, or \p getpeername() for
624 * \return A static character string identifying hostname and port of the
625 * chosen side in numeric host:port format.
627 * \sa getsockname(2), getpeername(2), parse_url(), getnameinfo(3),
628 * services(5), nsswitch.conf(5).
630 static char *__get_sock_name(int fd, typeof(getsockname) getname)
632 struct sockaddr_storage ss;
633 const struct sockaddr *sa;
634 socklen_t sslen = sizeof(ss);
635 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
636 static char output[sizeof(hbuf) + sizeof(sbuf) + 4];
639 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
640 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
641 fd, strerror(errno));
642 snprintf(output, sizeof(output), "(unknown)");
645 sa = normalize_ip_address(&ss);
646 ret = getnameinfo(sa, salen(sa), hbuf, sizeof(hbuf), sbuf,
647 sizeof(sbuf), NI_NUMERICHOST | NI_NUMERICSERV);
649 PARA_WARNING_LOG("hostname lookup error (%s).\n",
651 snprintf(output, sizeof(output), "(lookup error)");
652 } else if (sa->sa_family == AF_INET6)
653 snprintf(output, sizeof(output), "[%s]:%s", hbuf, sbuf);
655 snprintf(output, sizeof(output), "%s:%s", hbuf, sbuf);
660 * Look up the local side of a connected socket structure.
662 * \param sockfd The file descriptor of the socket.
664 * \return A pointer to a static buffer containing hostname an port. This
665 * buffer must not be freed by the caller.
669 char *local_name(int sockfd)
671 return __get_sock_name(sockfd, getsockname);
675 * Look up the remote side of a connected socket structure.
677 * \param sockfd The file descriptor of the socket.
679 * \return Analogous to the return value of \ref local_name() but for the
684 char *remote_name(int sockfd)
686 return __get_sock_name(sockfd, getpeername);
690 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
692 * \param ss Container of IPv4/6 address.
693 * \param ia Extracted IPv4 address (different from 0) or 0 if unsuccessful.
697 void extract_v4_addr(const struct sockaddr_storage *ss, struct in_addr *ia)
699 const struct sockaddr *sa = normalize_ip_address(ss);
701 memset(ia, 0, sizeof(*ia));
702 if (sa->sa_family == AF_INET)
703 *ia = ((struct sockaddr_in *)sa)->sin_addr;
707 * Receive data from a file descriptor.
709 * \param fd The file descriptor.
710 * \param buf The buffer to write the data to.
711 * \param size The size of \a buf.
713 * Receive at most \a size bytes from file descriptor \a fd.
715 * \return The number of bytes received on success, negative on errors, zero if
716 * the peer has performed an orderly shutdown.
720 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
724 n = recv(fd, buf, size, 0);
726 return -ERRNO_TO_PARA_ERROR(errno);
731 * Receive and write terminating NULL byte.
733 * \param fd The file descriptor.
734 * \param buf The buffer to write the data to.
735 * \param size The size of \a buf.
737 * Read at most \a size - 1 bytes from file descriptor \a fd and
738 * write a NULL byte at the end of the received data.
740 * \return The return value of the underlying call to \a recv_bin_buffer().
742 * \sa recv_bin_buffer()
744 int recv_buffer(int fd, char *buf, size_t size)
749 n = recv_bin_buffer(fd, buf, size - 1);
758 * Wrapper around the accept system call.
760 * \param fd The listening socket.
761 * \param rfds An optional fd_set pointer.
762 * \param addr Structure which is filled in with the address of the peer socket.
763 * \param size Should contain the size of the structure pointed to by \a addr.
764 * \param new_fd Result pointer.
766 * Accept incoming connections on \a addr, retry if interrupted. If \a rfds is
767 * not \p NULL, return 0 if \a fd is not set in \a rfds without calling accept().
769 * \return Negative on errors, zero if no connections are present to be accepted,
774 int para_accept(int fd, fd_set *rfds, void *addr, socklen_t size, int *new_fd)
778 if (rfds && !FD_ISSET(fd, rfds))
781 ret = accept(fd, (struct sockaddr *) addr, &size);
782 while (ret < 0 && errno == EINTR);
788 if (errno == EAGAIN || errno == EWOULDBLOCK)
790 return -ERRNO_TO_PARA_ERROR(errno);
794 * Probe the list of DCCP CCIDs configured on this host.
795 * \param ccid_array Pointer to return statically allocated array in.
796 * \return Number of elements returned in \a ccid_array or error.
798 * NB: This feature is only available on Linux > 2.6.30; on older kernels
799 * ENOPROTOOPT ("Protocol not available") will be returned.
801 int dccp_available_ccids(uint8_t **ccid_array)
803 static uint8_t ccids[DCCP_MAX_HOST_CCIDS];
804 socklen_t nccids = sizeof(ccids);
807 ret = fd = makesock(IPPROTO_DCCP, 1, NULL, 0, NULL);
811 if (getsockopt(fd, SOL_DCCP, DCCP_SOCKOPT_AVAILABLE_CCIDS,
812 ccids, &nccids) < 0) {
815 PARA_ERROR_LOG("No DCCP_SOCKOPT_AVAILABLE_CCIDS: %s\n",
817 return -ERRNO_TO_PARA_ERROR(ret);
826 * Prepare a structure for \p AF_UNIX socket addresses.
828 * \param u Pointer to the struct to be prepared.
829 * \param name The socket pathname.
831 * This just copies \a name to the sun_path component of \a u.
833 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
834 * than \p UNIX_PATH_MAX.
836 static int init_unix_addr(struct sockaddr_un *u, const char *name)
838 if (strlen(name) >= UNIX_PATH_MAX)
839 return -E_NAME_TOO_LONG;
840 memset(u->sun_path, 0, UNIX_PATH_MAX);
841 u->sun_family = PF_UNIX;
842 strcpy(u->sun_path, name);
847 * Prepare, create, and bind a socket for local communication.
849 * \param name The socket pathname.
850 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
851 * \param mode The desired mode of the socket.
853 * This function creates a local socket for sequenced, reliable,
854 * two-way, connection-based byte streams.
856 * \return The file descriptor, on success, negative on errors.
862 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
867 ret = init_unix_addr(unix_addr, name);
870 ret = socket(PF_UNIX, SOCK_STREAM, 0);
872 return -ERRNO_TO_PARA_ERROR(errno);
874 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
876 ret = -ERRNO_TO_PARA_ERROR(errno);
880 if (chmod(name, mode) < 0)
889 * Prepare, create, and connect to a Unix domain socket for local communication.
891 * \param name The socket pathname.
893 * This function creates a local socket for sequenced, reliable, two-way,
894 * connection-based byte streams.
896 * \return The file descriptor of the connected socket on success, negative on
899 * \sa create_local_socket(), unix(7), connect(2).
901 int connect_local_socket(const char *name)
903 struct sockaddr_un unix_addr;
906 PARA_DEBUG_LOG("connecting to %s\n", name);
907 ret = init_unix_addr(&unix_addr, name);
910 fd = socket(PF_UNIX, SOCK_STREAM, 0);
912 return -ERRNO_TO_PARA_ERROR(errno);
913 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) == -1) {
914 ret = -ERRNO_TO_PARA_ERROR(errno);
924 ssize_t send_cred_buffer(int sock, char *buf)
926 return write_buffer(sock, buf);
928 int recv_cred_buffer(int fd, char *buf, size_t size)
930 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
932 #else /* HAVE_UCRED */
934 * Send \p NULL-terminated buffer and Unix credentials of the current process.
936 * \param sock The socket file descriptor.
937 * \param buf The buffer to be sent.
939 * \return On success, this call returns the number of characters sent. On
940 * error, \p -E_SENDMSG is returned.
942 * \sa sendmsg(2), okir's Black Hats Manual.
944 ssize_t send_cred_buffer(int sock, char *buf)
946 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
948 struct cmsghdr *cmsg;
949 static struct iovec iov;
955 iov.iov_len = strlen(buf);
959 /* compose the message */
960 memset(&msg, 0, sizeof(msg));
963 msg.msg_control = control;
964 msg.msg_controllen = sizeof(control);
965 /* attach the ucred struct */
966 cmsg = CMSG_FIRSTHDR(&msg);
967 cmsg->cmsg_level = SOL_SOCKET;
968 cmsg->cmsg_type = SCM_CREDENTIALS;
969 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
970 *(struct ucred *)CMSG_DATA(cmsg) = c;
971 msg.msg_controllen = cmsg->cmsg_len;
972 ret = sendmsg(sock, &msg, 0);
978 static void dispose_fds(int *fds, unsigned num)
982 for (i = 0; i < num; i++)
987 * Receive a buffer and the Unix credentials of the sending process.
989 * \param fd the socket file descriptor.
990 * \param buf the buffer to store the message.
991 * \param size the size of \a buffer.
993 * \return negative on errors, the user id on success.
995 * \sa recvmsg(2), okir's Black Hats Manual.
997 int recv_cred_buffer(int fd, char *buf, size_t size)
1001 struct cmsghdr *cmsg;
1007 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
1008 memset(&msg, 0, sizeof(msg));
1009 memset(buf, 0, size);
1014 msg.msg_control = control;
1015 msg.msg_controllen = sizeof(control);
1016 if (recvmsg(fd, &msg, 0) < 0)
1018 result = -E_SCM_CREDENTIALS;
1019 cmsg = CMSG_FIRSTHDR(&msg);
1021 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
1022 == SCM_CREDENTIALS) {
1023 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
1026 if (cmsg->cmsg_level == SOL_SOCKET
1027 && cmsg->cmsg_type == SCM_RIGHTS) {
1028 dispose_fds((int *) CMSG_DATA(cmsg),
1029 (cmsg->cmsg_len - CMSG_LEN(0))
1032 cmsg = CMSG_NXTHDR(&msg, cmsg);
1036 #endif /* HAVE_UCRED */