2 * Copyright (C) 2005-2009 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
30 #include <openssl/rc4.h>
40 * Parse and validate IPv4 address/netmask string.
42 * \param cidr Address in CIDR notation
43 * \param addr Copy of the IPv4 address part of \a cidr
44 * \param addrlen Size of \a addr in bytes
45 * \param netmask Value of the netmask part in \a cidr or the
46 * default of 32 if not specified.
48 * \return Pointer to \a addr if succesful, NULL on error.
51 char *parse_cidr(const char *cidr,
52 char *addr, ssize_t addrlen,
56 char *c = addr, *end = c + (addrlen - 1);
60 if (cidr == NULL || addrlen < 1)
63 for (o = cidr; (*c = *o == '/'? '\0' : *o); c++, o++)
68 if (para_atoi32(++o, netmask) < 0 ||
69 *netmask < 0 || *netmask > 0x20)
72 if (is_valid_ipv4_address(addr))
81 * Match string as a candidate IPv4 address.
83 * \param address The string to match.
84 * \return True if \a address has "dot-quad" format.
86 static bool is_v4_dot_quad(const char *address)
91 assert(para_regcomp(&r, "^([0-9]+\\.){3}[0-9]+$",
92 REG_EXTENDED | REG_NOSUB) >= 0);
93 result = regexec(&r, address, 0, NULL, 0) == 0;
99 * Perform basic syntax checking on the host-part of an URL:
101 * - Since ':' is invalid in IPv4 addresses and DNS names, the
102 * presence of ':' causes interpretation as IPv6 address;
103 * - next the first-match-wins algorithm from RFC 3986 is applied;
104 * - else the string is considered as DNS name, to be resolved later.
106 * \param host The host string to check.
107 * \return True if \a host passes the syntax checks.
109 * \sa RFC 3986, 3.2.2; RFC 1123, 2.1; RFC 1034, 3.5
111 static bool host_string_ok(const char *host)
113 if (host == NULL || *host == '\0')
115 if (strchr(host, ':') != NULL)
116 return is_valid_ipv6_address(host);
117 if (is_v4_dot_quad(host))
118 return is_valid_ipv4_address(host);
123 * Parse and validate URL string.
125 * The URL syntax is loosely based on RFC 3986, supporting one of
126 * - "["host"]"[:port] for native IPv6 addresses and
127 * - host[:port] for IPv4 hostnames and DNS names.
129 * Native IPv6 addresses must be enclosed in square brackets, since
130 * otherwise there is an ambiguity with the port separator `:'.
131 * The 'port' part is always considered to be a number; if absent,
132 * it is set to -1, to indicate that a default port is to be used.
134 * The following are valid examples:
142 * \param url The URL string to take apart.
143 * \param host To return the copied host part of \a url.
144 * \param hostlen The maximum length of \a host.
145 * \param port To return the port number (if any) of \a url.
147 * \return Pointer to \a host, or NULL if failed.
148 * If NULL is returned, \a host and \a portnum are undefined. If no
149 * port number was present in \a url, \a portnum is set to -1.
151 * \sa RFC 3986, 3.2.2/3.2.3
153 char *parse_url(const char *url,
154 char *host, ssize_t hostlen,
158 char *c = host, *end = c + (hostlen - 1);
162 if (o == NULL || hostlen < 1)
166 for (++o; (*c = *o == ']' ? '\0' : *o); c++, o++)
170 if (*o++ != ']' || (*o != '\0' && *o != ':'))
173 for (; (*c = *o == ':'? '\0' : *o); c++, o++)
179 if (para_atoi32(++o, port) < 0 ||
180 *port < 0 || *port > 0xffff)
183 if (host_string_ok(host))
191 * Stringify port number, resolve into service name where defined.
192 * \param port 2-byte port number, in host-byte-order.
193 * \param transport Transport protocol name (e.g. "udp", "tcp"), or NULL.
194 * \return Pointer to static result buffer.
196 * \sa getservent(3), services(5), nsswitch.conf(5)
198 const char *stringify_port(int port, const char *transport)
200 static char service[NI_MAXSERV];
202 if (port < 0 || port > 0xFFFF) {
203 snprintf(service, sizeof(service), "undefined (%d)", port);
205 struct servent *se = getservbyport(htons(port), transport);
208 snprintf(service, sizeof(service), "%u", port);
210 snprintf(service, sizeof(service), "%s", se->s_name);
216 * Determine the socket type for a given layer-4 protocol.
218 * \param l4type The symbolic name of the transport-layer protocol.
220 * \sa ip(7), socket(2)
222 static inline int sock_type(const unsigned l4type)
225 case IPPROTO_UDP: return SOCK_DGRAM;
226 case IPPROTO_TCP: return SOCK_STREAM;
227 case IPPROTO_DCCP: return SOCK_DCCP;
229 return -1; /* not supported here */
233 * Pretty-print transport-layer name.
235 static const char *layer4_name(const unsigned l4type)
238 case IPPROTO_UDP: return "UDP";
239 case IPPROTO_TCP: return "TCP";
240 case IPPROTO_DCCP: return "DCCP";
242 return "UNKNOWN PROTOCOL";
246 * Resolve IPv4/IPv6 address and create a ready-to-use active or passive socket.
248 * \param l3type The layer-3 type (\p AF_INET, \p AF_INET6, \p AF_UNSPEC).
249 * \param l4type The layer-4 type (\p IPPROTO_xxx).
250 * \param passive Whether this is a passive (1) or active (0) socket.
251 * \param host Remote or local hostname or IPv/6 address string.
252 * \param port_number Decimal port number.
254 * This creates a ready-made IPv4/v6 socket structure after looking up the
255 * necessary parameters. The interpretation of \a host depends on the value of
257 * - on a passive socket host is interpreted as an interface IPv4/6 address
258 * (can be left NULL);
259 * - on an active socket, \a host is the peer DNS name or IPv4/6 address
261 * - \a port_number is in either case the numeric port number (not service
264 * Furthermore, bind(2) is called on passive sockets, and connect(2) on active
265 * sockets. The algorithm tries all possible address combinations until it
268 * \return This function returns 1 on success and \a -E_ADDRESS_LOOKUP when no
269 * matching connection could be set up (with details in the error log).
271 * \sa ipv6(7), getaddrinfo(3), bind(2), connect(2).
273 int makesock(unsigned l3type, unsigned l4type, int passive,
274 const char *host, unsigned short port_number)
276 struct addrinfo *local = NULL, *src,
277 *remote = NULL, *dst, hints;
278 int rc, on = 1, sockfd = -1,
279 socktype = sock_type(l4type);
280 char port[6]; /* port number has at most 5 digits */
282 sprintf(port, "%u", port_number);
283 /* Set up address hint structure */
284 memset(&hints, 0, sizeof(hints));
285 hints.ai_family = l3type;
286 hints.ai_socktype = socktype;
288 * getaddrinfo does not support SOCK_DCCP, so for the sake of lookup
289 * (and only then) pretend to be UDP.
291 if (l4type == IPPROTO_DCCP)
292 hints.ai_socktype = SOCK_DGRAM;
294 /* only use addresses available on the host */
295 hints.ai_flags = AI_ADDRCONFIG;
296 if (l3type == AF_INET6)
297 /* use v4-mapped-v6 if no v6 addresses found */
298 hints.ai_flags |= AI_V4MAPPED | AI_ALL;
300 if (passive && host == NULL)
301 hints.ai_flags |= AI_PASSIVE;
303 /* Obtain local/remote address information */
304 if ((rc = getaddrinfo(host, port, &hints, passive ? &local : &remote))) {
305 PARA_ERROR_LOG("can not resolve %s address %s#%s: %s.\n",
307 host? host : (passive? "[loopback]" : "[localhost]"),
308 port, gai_strerror(rc));
309 return -E_ADDRESS_LOOKUP;
312 /* Iterate over all src/dst combination, exhausting dst first */
313 for (src = local, dst = remote; src != NULL || dst != NULL; /* no op */ ) {
314 if (src && dst && src->ai_family == AF_INET
315 && dst->ai_family == AF_INET6)
316 goto get_next_dst; /* v4 -> v6 is not possible */
318 sockfd = socket(src ? src->ai_family : dst->ai_family,
324 * Set those options that need to be set before establishing
325 * the connection. Reuse the address on passive (listening)
326 * sockets to avoid failure on restart.
328 if (passive && setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
329 &on, sizeof(on)) == -1) {
330 PARA_ERROR_LOG("can not set SO_REUSEADDR: %s\n",
332 return -ERRNO_TO_PARA_ERROR(errno);
336 if (bind(sockfd, src->ai_addr, src->ai_addrlen) < 0) {
340 if (!dst) /* bind-only completed successfully */
344 if (dst && connect(sockfd, dst->ai_addr, dst->ai_addrlen) == 0)
345 break; /* connection completed successfully */
348 if (dst && (dst = dst->ai_next))
351 if (src && (src = src->ai_next)) /* restart inner loop */
357 freeaddrinfo(remote);
359 if (src == NULL && dst == NULL) {
360 PARA_ERROR_LOG("can not create %s socket %s#%s.\n",
361 layer4_name(l4type), host? host : (passive?
362 "[loopback]" : "[localhost]"), port);
363 return -ERRNO_TO_PARA_ERROR(errno);
369 * Create a passive / listening socket.
371 * \param l3type The network-layer type (\p AF_xxx).
372 * \param l4type The transport-layer type (\p IPPROTO_xxx).
373 * \param port The decimal port number to listen on.
375 * \return Positive integer (socket descriptor) on success, negative value
378 * \sa makesock(), ip(7), ipv6(7), bind(2), listen(2).
380 int para_listen(unsigned l3type, unsigned l4type, unsigned short port)
382 int ret, fd = makesock(l3type, l4type, 1, NULL, port);
385 ret = listen(fd, BACKLOG);
388 return -ERRNO_TO_PARA_ERROR(errno);
390 PARA_INFO_LOG("listening on %s port %u, fd %d\n",
391 layer4_name(l4type), port, fd);
397 * Determine IPv4/v6 socket address length.
398 * \param sa Container of IPv4 or IPv6 address.
399 * \return Address-family dependent address length.
401 static socklen_t salen(const struct sockaddr *sa)
403 assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
405 return sa->sa_family == AF_INET6
406 ? sizeof(struct sockaddr_in6)
407 : sizeof(struct sockaddr_in);
411 * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
412 * \param ss Container of IPv4/6 address.
413 * \return Pointer to normalized address (may be static storage).
417 static const struct sockaddr *
418 normalize_ip_address(const struct sockaddr_storage *ss)
420 const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
422 assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
424 if (ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr)) {
425 static struct sockaddr_in ia;
427 ia.sin_family = AF_INET;
428 ia.sin_port = ia6->sin6_port;
429 memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
430 return (const struct sockaddr *)&ia;
432 return (const struct sockaddr *)ss;
436 * Print numeric host and port number (beware - uses static char).
438 * \param sa The IPv4/IPv6 socket address to use.
440 * \sa getnameinfo(3), services(5), nsswitch.conf(5)
442 static char *host_and_port(const struct sockaddr_storage *ss)
444 const struct sockaddr *sa = normalize_ip_address(ss);
445 char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
446 static char output[sizeof(hbuf) + sizeof(sbuf) + 2];
449 ret = getnameinfo(sa, salen(sa),
454 snprintf(output, sizeof(output), "%s#%s", hbuf, sbuf);
456 snprintf(output, sizeof(output), "(unknown)");
457 PARA_WARNING_LOG("hostname lookup error (%s).\n",
464 * Look up the local or remote side of a connected socket structure.
466 * \param fd The socket descriptor of the connected socket.
467 * \param getname Either \p getsockname() for local, or \p getpeername() for
470 * \return A static character string identifying hostname and port of the
473 * \sa getsockname(2), getpeername(2).
475 static char *__get_sock_name(int fd, int (*getname)(int, struct sockaddr*,
478 struct sockaddr_storage ss;
479 socklen_t sslen = sizeof(ss);
481 if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
482 static char *dont_know = "(don't know)";
483 PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
484 fd, strerror(errno));
487 return host_and_port(&ss);
491 * Look up the local side of a connected socket structure.
493 * \param sockfd The file descriptor of the socket.
495 * \return A pointer to a static buffer containing hostname an port. This
496 * buffer must not be freed by the caller.
500 char *local_name(int sockfd)
502 return __get_sock_name(sockfd, getsockname);
506 * Look up the remote side of a connected socket structure.
508 * \param sockfd The file descriptor of the socket.
510 * \return Analogous to the return value of \ref local_name() but for the
515 char *remote_name(int sockfd)
517 return __get_sock_name(sockfd, getpeername);
521 * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
522 * \param ss Container of IPv4/6 address
523 * \return Extracted IPv4 address (different from 0) or 0 if unsuccessful.
527 struct in_addr extract_v4_addr(const struct sockaddr_storage *ss)
529 struct in_addr ia = {.s_addr = 0};
530 const struct sockaddr *sa = normalize_ip_address(ss);
532 if (sa->sa_family == AF_INET)
533 ia = ((struct sockaddr_in *)sa)->sin_addr;
538 * Send a binary buffer.
540 * \param fd The file descriptor.
541 * \param buf The buffer to be sent.
542 * \param len The length of \a buf.
544 * Send out the buffer and try to resend the remaining part in case of short
549 int send_bin_buffer(int fd, const char *buf, size_t len)
552 PARA_CRIT_LOG("len == 0\n");
553 return write_all(fd, buf, &len);
557 * Send a \p NULL-terminated buffer.
559 * \param fd The file descriptor.
560 * \param buf The null-terminated buffer to be send.
562 * This is equivalent to send_bin_buffer(fd, buf, strlen(buf)).
566 int send_buffer(int fd, const char *buf)
568 return send_bin_buffer(fd, buf, strlen(buf));
572 * Send a buffer given by a format string.
574 * \param fd The file descriptor.
575 * \param fmt A format string.
579 __printf_2_3 int send_va_buffer(int fd, const char *fmt, ...)
584 PARA_VSPRINTF(fmt, msg);
585 ret = send_buffer(fd, msg);
591 * Receive data from a file descriptor.
593 * \param fd The file descriptor.
594 * \param buf The buffer to write the data to.
595 * \param size The size of \a buf.
597 * Receive at most \a size bytes from file descriptor \a fd.
599 * \return The number of bytes received on success, negative on errors, zero if
600 * the peer has performed an orderly shutdown.
604 __must_check int recv_bin_buffer(int fd, char *buf, size_t size)
608 n = recv(fd, buf, size, 0);
610 return -ERRNO_TO_PARA_ERROR(errno);
615 * Receive and write terminating NULL byte.
617 * \param fd The file descriptor.
618 * \param buf The buffer to write the data to.
619 * \param size The size of \a buf.
621 * Read at most \a size - 1 bytes from file descriptor \a fd and
622 * write a NULL byte at the end of the received data.
624 * \return The return value of the underlying call to \a recv_bin_buffer().
626 * \sa recv_bin_buffer()
628 int recv_buffer(int fd, char *buf, size_t size)
633 n = recv_bin_buffer(fd, buf, size - 1);
642 * Wrapper around the accept system call.
644 * \param fd The listening socket.
645 * \param addr Structure which is filled in with the address of the peer socket.
646 * \param size Should contain the size of the structure pointed to by \a addr.
648 * Accept incoming connections on \a addr. Retry if interrupted.
650 * \return The new file descriptor on success, negative on errors.
654 int para_accept(int fd, void *addr, socklen_t size)
659 new_fd = accept(fd, (struct sockaddr *) addr, &size);
660 while (new_fd < 0 && errno == EINTR);
661 return new_fd < 0? -ERRNO_TO_PARA_ERROR(errno) : new_fd;
665 * Prepare a structure for \p AF_UNIX socket addresses.
667 * \param u Pointer to the struct to be prepared.
668 * \param name The socket pathname.
670 * This just copies \a name to the sun_path component of \a u.
672 * \return Positive on success, \p -E_NAME_TOO_LONG if \a name is longer
673 * than \p UNIX_PATH_MAX.
675 static int init_unix_addr(struct sockaddr_un *u, const char *name)
677 if (strlen(name) >= UNIX_PATH_MAX)
678 return -E_NAME_TOO_LONG;
679 memset(u->sun_path, 0, UNIX_PATH_MAX);
680 u->sun_family = PF_UNIX;
681 strcpy(u->sun_path, name);
686 * Prepare, create, and bind a socket for local communication.
688 * \param name The socket pathname.
689 * \param unix_addr Pointer to the \p AF_UNIX socket structure.
690 * \param mode The desired mode of the socket.
692 * This function creates a local socket for sequenced, reliable,
693 * two-way, connection-based byte streams.
695 * \return The file descriptor, on success, negative on errors.
701 int create_local_socket(const char *name, struct sockaddr_un *unix_addr,
706 ret = init_unix_addr(unix_addr, name);
709 ret = socket(PF_UNIX, SOCK_STREAM, 0);
711 return -ERRNO_TO_PARA_ERROR(errno);
713 ret = bind(fd, (struct sockaddr *) unix_addr, UNIX_PATH_MAX);
715 ret = -ERRNO_TO_PARA_ERROR(errno);
719 if (chmod(name, mode) < 0)
728 * Prepare, create, and connect to a Unix domain socket for local communication.
730 * \param name The socket pathname.
732 * This function creates a local socket for sequenced, reliable, two-way,
733 * connection-based byte streams.
735 * \return The file descriptor, on success, negative on errors.
737 * \sa create_local_socket(), unix(7), connect(2).
739 int create_remote_socket(const char *name)
741 struct sockaddr_un unix_addr;
744 ret = init_unix_addr(&unix_addr, name);
747 fd = socket(PF_UNIX, SOCK_STREAM, 0);
749 return -ERRNO_TO_PARA_ERROR(errno);
750 if (connect(fd, (struct sockaddr *)&unix_addr, sizeof(unix_addr)) == -1) {
751 ret = -ERRNO_TO_PARA_ERROR(errno);
761 ssize_t send_cred_buffer(int sock, char *buf)
763 return send_buffer(sock, buf);
765 int recv_cred_buffer(int fd, char *buf, size_t size)
767 return recv_buffer(fd, buf, size) > 0? 1 : -E_RECVMSG;
769 #else /* HAVE_UCRED */
771 * Send \p NULL-terminated buffer and Unix credentials of the current process.
773 * \param sock The socket file descriptor.
774 * \param buf The buffer to be sent.
776 * \return On success, this call returns the number of characters sent. On
777 * error, \p -E_SENDMSG is returned.
779 * \sa sendmsg(2), okir's Black Hats Manual.
781 ssize_t send_cred_buffer(int sock, char *buf)
783 char control[sizeof(struct cmsghdr) + sizeof(struct ucred)];
785 struct cmsghdr *cmsg;
786 static struct iovec iov;
792 iov.iov_len = strlen(buf);
796 /* compose the message */
797 memset(&msg, 0, sizeof(msg));
800 msg.msg_control = control;
801 msg.msg_controllen = sizeof(control);
802 /* attach the ucred struct */
803 cmsg = CMSG_FIRSTHDR(&msg);
804 cmsg->cmsg_level = SOL_SOCKET;
805 cmsg->cmsg_type = SCM_CREDENTIALS;
806 cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
807 *(struct ucred *)CMSG_DATA(cmsg) = c;
808 msg.msg_controllen = cmsg->cmsg_len;
809 ret = sendmsg(sock, &msg, 0);
815 static void dispose_fds(int *fds, unsigned num)
819 for (i = 0; i < num; i++)
824 * Receive a buffer and the Unix credentials of the sending process.
826 * \param fd the socket file descriptor.
827 * \param buf the buffer to store the message.
828 * \param size the size of \a buffer.
830 * \return negative on errors, the user id on success.
832 * \sa recvmsg(2), okir's Black Hats Manual.
834 int recv_cred_buffer(int fd, char *buf, size_t size)
838 struct cmsghdr *cmsg;
844 setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &yes, sizeof(int));
845 memset(&msg, 0, sizeof(msg));
846 memset(buf, 0, size);
851 msg.msg_control = control;
852 msg.msg_controllen = sizeof(control);
853 if (recvmsg(fd, &msg, 0) < 0)
855 result = -E_SCM_CREDENTIALS;
856 cmsg = CMSG_FIRSTHDR(&msg);
858 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type
859 == SCM_CREDENTIALS) {
860 memcpy(&cred, CMSG_DATA(cmsg), sizeof(struct ucred));
863 if (cmsg->cmsg_level == SOL_SOCKET
864 && cmsg->cmsg_type == SCM_RIGHTS) {
865 dispose_fds((int *) CMSG_DATA(cmsg),
866 (cmsg->cmsg_len - CMSG_LEN(0))
869 cmsg = CMSG_NXTHDR(&msg, cmsg);
873 #endif /* HAVE_UCRED */
876 * Receive a buffer and check for a pattern.
878 * \param fd The file descriptor to receive from.
879 * \param pattern The expected pattern.
880 * \param bufsize The size of the internal buffer.
882 * \return Positive if \a pattern was received, negative otherwise.
884 * This function tries to receive at most \a bufsize bytes from file descriptor
885 * \a fd. If at least \p strlen(\a pattern) bytes were received, the beginning
886 * of the received buffer is compared with \a pattern, ignoring case.
888 * \sa recv_buffer(), \sa strncasecmp(3).
890 int recv_pattern(int fd, const char *pattern, size_t bufsize)
892 size_t len = strlen(pattern);
893 char *buf = para_malloc(bufsize + 1);
894 int ret = -E_RECV_PATTERN, n = recv_buffer(fd, buf, bufsize + 1);
898 if (strncasecmp(buf, pattern, len))
903 PARA_NOTICE_LOG("did not receive pattern '%s'\n", pattern);
905 PARA_NOTICE_LOG("recvd %d bytes: %s\n", n, buf);
907 PARA_NOTICE_LOG("%s\n", para_strerror(-n));