2 * network.c -- Provide common network functions for NFS mount/umount
4 * Copyright (C) 2007 Oracle. All rights reserved.
5 * Copyright (C) 2007 Chuck Lever <chuck.lever@oracle.com>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
17 * You should have received a copy of the GNU General Public
18 * License along with this program; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 021110-1307, USA.
37 #include <sys/types.h>
38 #include <sys/socket.h>
40 #include <netinet/in.h>
42 #include <rpc/pmap_prot.h>
43 #include <rpc/pmap_clnt.h>
48 #include "nfs_mount.h"
49 #include "mount_constants.h"
54 * Earlier versions of glibc's /usr/include/netdb.h exclude these
55 * definitions because it was thought they were not part of a stable
56 * POSIX standard. However, they are defined by RFC 2553 and 3493
57 * and in POSIX 1003.1-2001, so these definitions were added in later
58 * versions of netdb.h.
61 #define AI_V4MAPPED 0x0008 /* IPv4-mapped addresses are acceptable. */
62 #endif /* AI_V4MAPPED */
64 #define AI_ALL 0x0010 /* Return both IPv4 and IPv6 addresses. */
67 #define AI_ADDRCONFIG 0x0020 /* Use configuration of this host to choose \
68 returned address type. */
69 #endif /* AI_ADDRCONFIG */
71 #define PMAP_TIMEOUT (10)
72 #define CONNECT_TIMEOUT (20)
73 #define MOUNT_TIMEOUT (30)
75 #if SIZEOF_SOCKLEN_T - 0 == 0
76 #define socklen_t unsigned int
79 extern int nfs_mount_data_version;
80 extern char *progname;
83 static const char *nfs_ns_pgmtbl[] = {
88 static const unsigned long nfs_to_mnt[] = {
95 static const unsigned long mnt_to_nfs[] = {
103 * Map an NFS version into the corresponding Mountd version
105 unsigned long nfsvers_to_mnt(const unsigned long vers)
108 return nfs_to_mnt[vers];
113 * Map a Mountd version into the corresponding NFS version
115 static unsigned long mntvers_to_nfs(const unsigned long vers)
118 return mnt_to_nfs[vers];
122 static const unsigned int probe_udp_only[] = {
127 static const unsigned int probe_udp_first[] = {
133 static const unsigned int probe_tcp_first[] = {
139 static const unsigned long probe_nfs2_only[] = {
144 static const unsigned long probe_nfs3_first[] = {
150 static const unsigned long probe_mnt1_first[] = {
156 static const unsigned long probe_mnt3_first[] = {
164 * nfs_name_to_address - resolve hostname to an IPv4 or IPv6 socket address
165 * @hostname: pointer to C string containing DNS hostname to resolve
166 * @sap: pointer to buffer to fill with socket address
167 * @len: IN: size of buffer to fill; OUT: size of socket address
169 * Returns 1 and places a socket address at @sap if successful;
172 int nfs_name_to_address(const char *hostname,
173 const sa_family_t af_hint,
174 struct sockaddr *sap, socklen_t *salen)
176 struct addrinfo *gai_results;
177 struct addrinfo gai_hint = {
178 .ai_family = af_hint,
179 .ai_flags = AI_ADDRCONFIG,
181 socklen_t len = *salen;
184 if (af_hint == AF_INET6)
185 gai_hint.ai_flags |= AI_V4MAPPED|AI_ALL;
189 error = getaddrinfo(hostname, NULL, &gai_hint, &gai_results);
191 nfs_error(_("%s: DNS resolution failed for %s: %s"),
192 progname, hostname, (error == EAI_SYSTEM ?
193 strerror(errno) : gai_strerror(error)));
197 switch (gai_results->ai_addr->sa_family) {
200 if (len >= gai_results->ai_addrlen) {
201 *salen = gai_results->ai_addrlen;
202 memcpy(sap, gai_results->ai_addr, *salen);
207 /* things are really broken if we get here, so warn */
208 nfs_error(_("%s: unrecognized DNS resolution results for %s"),
213 freeaddrinfo(gai_results);
218 * nfs_gethostbyname - resolve a hostname to an IPv4 address
219 * @hostname: pointer to a C string containing a DNS hostname
220 * @saddr: returns an IPv4 address
222 * Returns 1 if successful, otherwise zero.
224 int nfs_gethostbyname(const char *hostname, struct sockaddr_in *sin)
226 socklen_t len = sizeof(*sin);
228 return nfs_name_to_address(hostname, AF_INET,
229 (struct sockaddr *)sin, &len);
233 * nfs_string_to_sockaddr - convert string address to sockaddr
234 * @address: pointer to presentation format address to convert
235 * @addrlen: length of presentation address
236 * @sap: pointer to socket address buffer to fill in
237 * @salen: IN: length of address buffer
238 * OUT: length of converted socket address
240 * Convert a presentation format address string to a socket address.
241 * Similar to nfs_name_to_address(), but the DNS query is squelched,
242 * and won't make any noise if the getaddrinfo() call fails.
244 * Returns 1 and fills in @sap and @salen if successful; otherwise zero.
246 * See RFC 4038 section 5.1 or RFC 3513 section 2.2 for more details
247 * on presenting IPv6 addresses as text strings.
249 int nfs_string_to_sockaddr(const char *address, const size_t addrlen,
250 struct sockaddr *sap, socklen_t *salen)
252 struct addrinfo *gai_results;
253 struct addrinfo gai_hint = {
254 .ai_flags = AI_NUMERICHOST,
256 socklen_t len = *salen;
261 if (getaddrinfo(address, NULL, &gai_hint, &gai_results) == 0) {
262 switch (gai_results->ai_addr->sa_family) {
265 if (len >= gai_results->ai_addrlen) {
266 *salen = gai_results->ai_addrlen;
267 memcpy(sap, gai_results->ai_addr, *salen);
272 freeaddrinfo(gai_results);
279 * nfs_present_sockaddr - convert sockaddr to string
280 * @sap: pointer to socket address to convert
281 * @salen: length of socket address
282 * @buf: pointer to buffer to fill in
283 * @buflen: length of buffer
285 * Convert the passed-in sockaddr-style address to presentation format.
286 * The presentation format address is placed in @buf and is
289 * Returns 1 if successful; otherwise zero.
291 * See RFC 4038 section 5.1 or RFC 3513 section 2.2 for more details
292 * on presenting IPv6 addresses as text strings.
294 int nfs_present_sockaddr(const struct sockaddr *sap, const socklen_t salen,
295 char *buf, const size_t buflen)
297 #ifdef HAVE_GETNAMEINFO
300 result = getnameinfo(sap, salen, buf, buflen,
301 NULL, 0, NI_NUMERICHOST);
305 nfs_error(_("%s: invalid server address: %s"), progname,
306 gai_strerror(result));
308 #else /* HAVE_GETNAMEINFO */
311 if (sap->sa_family == AF_INET) {
312 addr = inet_ntoa(((struct sockaddr_in *)sap)->sin_addr);
313 if (addr && strlen(addr) < buflen) {
319 nfs_error(_("%s: invalid server address"), progname);
321 #endif /* HAVE_GETNAMEINFO */
325 * Attempt to connect a socket, but time out after "timeout" seconds.
327 * On error return, caller closes the socket.
329 static int connect_to(int fd, struct sockaddr *addr,
330 socklen_t addrlen, int timeout)
334 struct timeval tv = {
338 saved = fcntl(fd, F_GETFL, 0);
339 fcntl(fd, F_SETFL, saved | O_NONBLOCK);
341 ret = connect(fd, addr, addrlen);
342 if (ret < 0 && errno != EINPROGRESS)
350 ret = select(fd + 1, &rset, &wset, NULL, &tv);
355 if (FD_ISSET(fd, &rset) || FD_ISSET(fd, &wset)) {
357 socklen_t len = sizeof(error);
358 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &error, &len) < 0)
368 fcntl(fd, F_SETFL, saved);
373 * Create a socket that is locally bound to a reserved or non-reserved port.
375 * The caller should check rpc_createerr to determine the cause of any error.
377 static int get_socket(struct sockaddr_in *saddr, unsigned int p_prot,
378 unsigned int timeout, int resvp, int conn)
381 struct sockaddr_in laddr;
382 socklen_t namelen = sizeof(laddr);
384 type = (p_prot == IPPROTO_UDP ? SOCK_DGRAM : SOCK_STREAM);
385 if ((so = socket (AF_INET, type, p_prot)) < 0)
388 laddr.sin_family = AF_INET;
390 laddr.sin_addr.s_addr = htonl(INADDR_ANY);
392 if (bindresvport(so, &laddr) < 0)
393 goto err_bindresvport;
395 cc = bind(so, (struct sockaddr *)&laddr, namelen);
399 if (type == SOCK_STREAM || (conn && type == SOCK_DGRAM)) {
400 cc = connect_to(so, (struct sockaddr *)saddr, namelen,
408 rpc_createerr.cf_stat = RPC_SYSTEMERROR;
409 rpc_createerr.cf_error.re_errno = errno;
411 nfs_error(_("%s: Unable to create %s socket: errno %d (%s)\n"),
412 progname, p_prot == IPPROTO_UDP ? _("UDP") : _("TCP"),
413 errno, strerror(errno));
418 rpc_createerr.cf_stat = RPC_SYSTEMERROR;
419 rpc_createerr.cf_error.re_errno = errno;
421 nfs_error(_("%s: Unable to bindresvport %s socket: errno %d"
423 progname, p_prot == IPPROTO_UDP ? _("UDP") : _("TCP"),
424 errno, strerror(errno));
430 rpc_createerr.cf_stat = RPC_SYSTEMERROR;
431 rpc_createerr.cf_error.re_errno = errno;
433 nfs_error(_("%s: Unable to bind to %s socket: errno %d (%s)\n"),
434 progname, p_prot == IPPROTO_UDP ? _("UDP") : _("TCP"),
435 errno, strerror(errno));
441 rpc_createerr.cf_stat = RPC_SYSTEMERROR;
442 rpc_createerr.cf_error.re_errno = errno;
444 nfs_error(_("%s: Unable to connect to %s:%d, errno %d (%s)\n"),
445 progname, inet_ntoa(saddr->sin_addr),
446 ntohs(saddr->sin_port), errno, strerror(errno));
453 * getport() is very similar to pmap_getport() with the exception that
454 * this version tries to use an ephemeral port, since reserved ports are
455 * not needed for GETPORT queries. This conserves the very limited
456 * reserved port space, which helps reduce failed socket binds
457 * during mount storms.
459 * A side effect of calling this function is that rpccreateerr is set.
461 static unsigned short getport(struct sockaddr_in *saddr,
462 unsigned long program,
463 unsigned long version,
466 struct sockaddr_in bind_saddr;
467 unsigned short port = 0;
473 bind_saddr.sin_port = htons(PMAPPORT);
475 socket = get_socket(&bind_saddr, proto, PMAP_TIMEOUT, FALSE, TRUE);
476 if (socket == RPC_ANYSOCK) {
477 if (proto == IPPROTO_TCP &&
478 rpc_createerr.cf_error.re_errno == ETIMEDOUT)
479 rpc_createerr.cf_stat = RPC_TIMEDOUT;
485 clnt = clntudp_bufcreate(&bind_saddr,
487 RETRY_TIMEOUT, &socket,
492 clnt = clnttcp_create(&bind_saddr,
495 RPCSMALLMSGSIZE, RPCSMALLMSGSIZE);
499 struct pmap parms = {
505 stat = clnt_call(clnt, PMAPPROC_GETPORT,
506 (xdrproc_t)xdr_pmap, (caddr_t)&parms,
507 (xdrproc_t)xdr_u_short, (caddr_t)&port,
510 clnt_geterr(clnt, &rpc_createerr.cf_error);
511 rpc_createerr.cf_stat = stat;
514 if (stat != RPC_SUCCESS)
517 rpc_createerr.cf_stat = RPC_PROGNOTREGISTERED;
525 * Use the portmapper to discover whether or not the service we want is
526 * available. The lists 'versions' and 'protos' define ordered sequences
527 * of service versions and udp/tcp protocols to probe for.
529 static int probe_port(clnt_addr_t *server, const unsigned long *versions,
530 const unsigned int *protos)
532 struct sockaddr_in *saddr = &server->saddr;
533 struct pmap *pmap = &server->pmap;
534 const unsigned long prog = pmap->pm_prog, *p_vers;
535 const unsigned int prot = (u_int)pmap->pm_prot, *p_prot;
536 const u_short port = (u_short) pmap->pm_port;
537 unsigned long vers = pmap->pm_vers;
538 unsigned short p_port;
540 p_prot = prot ? &prot : protos;
541 p_vers = vers ? &vers : versions;
542 rpc_createerr.cf_stat = 0;
544 p_port = getport(saddr, prog, *p_vers, *p_prot);
546 if (!port || port == p_port) {
547 saddr->sin_port = htons(p_port);
549 printf(_("%s: trying %s prog %ld vers "
550 "%ld prot %s port %d\n"),
552 inet_ntoa(saddr->sin_addr),
554 *p_prot == IPPROTO_UDP ?
558 if (clnt_ping(saddr, prog, *p_vers, *p_prot, NULL))
562 if (rpc_createerr.cf_stat != RPC_PROGNOTREGISTERED &&
563 rpc_createerr.cf_stat != RPC_TIMEDOUT &&
564 rpc_createerr.cf_stat != RPC_CANTRECV &&
565 rpc_createerr.cf_stat != RPC_PROGVERSMISMATCH)
573 if (rpc_createerr.cf_stat == RPC_TIMEDOUT ||
574 rpc_createerr.cf_stat == RPC_CANTRECV)
577 if (vers || !*++p_vers)
586 pmap->pm_vers = *p_vers;
588 pmap->pm_prot = *p_prot;
590 pmap->pm_port = p_port;
591 rpc_createerr.cf_stat = 0;
595 static int probe_nfsport(clnt_addr_t *nfs_server)
597 struct pmap *pmap = &nfs_server->pmap;
599 if (pmap->pm_vers && pmap->pm_prot && pmap->pm_port)
602 if (nfs_mount_data_version >= 4)
603 return probe_port(nfs_server, probe_nfs3_first, probe_tcp_first);
605 return probe_port(nfs_server, probe_nfs2_only, probe_udp_only);
608 static int probe_mntport(clnt_addr_t *mnt_server)
610 struct pmap *pmap = &mnt_server->pmap;
612 if (pmap->pm_vers && pmap->pm_prot && pmap->pm_port)
615 if (nfs_mount_data_version >= 4)
616 return probe_port(mnt_server, probe_mnt3_first, probe_udp_first);
618 return probe_port(mnt_server, probe_mnt1_first, probe_udp_only);
622 * probe_bothports - discover the RPC endpoints of mountd and NFS server
623 * @mnt_server: pointer to address and pmap argument for mountd results
624 * @nfs_server: pointer to address and pmap argument for NFS server
626 * Returns 1 if successful, otherwise zero if some error occurred.
627 * Note that the arguments are both input and output arguments.
629 * A side effect of calling this function is that rpccreateerr is set.
631 int probe_bothports(clnt_addr_t *mnt_server, clnt_addr_t *nfs_server)
633 struct pmap *nfs_pmap = &nfs_server->pmap;
634 struct pmap *mnt_pmap = &mnt_server->pmap;
635 struct pmap save_nfs, save_mnt;
637 const unsigned long *probe_vers;
639 if (mnt_pmap->pm_vers && !nfs_pmap->pm_vers)
640 nfs_pmap->pm_vers = mntvers_to_nfs(mnt_pmap->pm_vers);
641 else if (nfs_pmap->pm_vers && !mnt_pmap->pm_vers)
642 mnt_pmap->pm_vers = nfsvers_to_mnt(nfs_pmap->pm_vers);
643 if (nfs_pmap->pm_vers)
646 memcpy(&save_nfs, nfs_pmap, sizeof(save_nfs));
647 memcpy(&save_mnt, mnt_pmap, sizeof(save_mnt));
648 probe_vers = (nfs_mount_data_version >= 4) ?
649 probe_mnt3_first : probe_mnt1_first;
651 for (; *probe_vers; probe_vers++) {
652 nfs_pmap->pm_vers = mntvers_to_nfs(*probe_vers);
653 if ((res = probe_nfsport(nfs_server) != 0)) {
654 mnt_pmap->pm_vers = *probe_vers;
655 if ((res = probe_mntport(mnt_server)) != 0)
657 memcpy(mnt_pmap, &save_mnt, sizeof(*mnt_pmap));
659 switch (rpc_createerr.cf_stat) {
660 case RPC_PROGVERSMISMATCH:
661 case RPC_PROGNOTREGISTERED:
666 memcpy(nfs_pmap, &save_nfs, sizeof(*nfs_pmap));
673 if (!probe_nfsport(nfs_server))
675 return probe_mntport(mnt_server);
678 static int nfs_probe_statd(void)
680 struct sockaddr_in addr = {
681 .sin_family = AF_INET,
682 .sin_addr.s_addr = htonl(INADDR_LOOPBACK),
684 rpcprog_t program = nfs_getrpcbyname(NSMPROG, nfs_ns_pgmtbl);
686 return nfs_getport_ping((struct sockaddr *)&addr, sizeof(addr),
687 program, (rpcvers_t)1, IPPROTO_UDP);
691 * start_statd - attempt to start rpc.statd
693 * Returns 1 if statd is running; otherwise zero.
695 int start_statd(void)
701 if (nfs_probe_statd())
705 if (stat(START_STATD, &stb) == 0) {
706 if (S_ISREG(stb.st_mode) && (stb.st_mode & S_IXUSR)) {
710 execl(START_STATD, START_STATD, NULL);
713 nfs_error(_("fork failed: %s"),
716 default: /* parent */
717 waitpid(pid, NULL,0);
720 if (nfs_probe_statd())
730 * nfs_call_umount - ask the server to remove a share from it's rmtab
731 * @mnt_server: address of RPC MNT program server
732 * @argp: directory path of share to "unmount"
734 * Returns one if the unmount call succeeded; zero if the unmount
735 * failed for any reason.
737 * Note that a side effect of calling this function is that rpccreateerr
740 int nfs_call_umount(clnt_addr_t *mnt_server, dirpath *argp)
743 enum clnt_stat res = 0;
746 if (!probe_mntport(mnt_server))
748 clnt = mnt_openclnt(mnt_server, &msock);
751 res = clnt_call(clnt, MOUNTPROC_UMNT,
752 (xdrproc_t)xdr_dirpath, (caddr_t)argp,
753 (xdrproc_t)xdr_void, NULL,
755 mnt_closeclnt(clnt, msock);
757 if (res == RPC_SUCCESS)
763 * mnt_openclnt - get a handle for a remote mountd service
764 * @mnt_server: address and pmap arguments of mountd service
765 * @msock: returns a file descriptor of the underlying transport socket
767 * Returns an active handle for the remote's mountd service
769 CLIENT *mnt_openclnt(clnt_addr_t *mnt_server, int *msock)
771 struct sockaddr_in *mnt_saddr = &mnt_server->saddr;
772 struct pmap *mnt_pmap = &mnt_server->pmap;
775 mnt_saddr->sin_port = htons((u_short)mnt_pmap->pm_port);
776 *msock = get_socket(mnt_saddr, mnt_pmap->pm_prot, MOUNT_TIMEOUT,
778 if (*msock == RPC_ANYSOCK) {
779 if (rpc_createerr.cf_error.re_errno == EADDRINUSE)
781 * Probably in-use by a TIME_WAIT connection,
782 * It is worth waiting a while and trying again.
784 rpc_createerr.cf_stat = RPC_TIMEDOUT;
788 switch (mnt_pmap->pm_prot) {
790 clnt = clntudp_bufcreate(mnt_saddr,
791 mnt_pmap->pm_prog, mnt_pmap->pm_vers,
792 RETRY_TIMEOUT, msock,
793 MNT_SENDBUFSIZE, MNT_RECVBUFSIZE);
796 clnt = clnttcp_create(mnt_saddr,
797 mnt_pmap->pm_prog, mnt_pmap->pm_vers,
799 MNT_SENDBUFSIZE, MNT_RECVBUFSIZE);
803 /* try to mount hostname:dirname */
804 clnt->cl_auth = authunix_create_default();
811 * mnt_closeclnt - terminate a handle for a remote mountd service
812 * @clnt: pointer to an active handle for a remote mountd service
813 * @msock: file descriptor of the underlying transport socket
816 void mnt_closeclnt(CLIENT *clnt, int msock)
818 auth_destroy(clnt->cl_auth);
824 * clnt_ping - send an RPC ping to the remote RPC service endpoint
825 * @saddr: server's address
826 * @prog: target RPC program number
827 * @vers: target RPC version number
828 * @prot: target RPC protocol
829 * @caddr: filled in with our network address
831 * Sigh... getport() doesn't actually check the version number.
832 * In order to make sure that the server actually supports the service
833 * we're requesting, we open and RPC client, and fire off a NULL
836 * caddr is the network address that the server will use to call us back.
837 * On multi-homed clients, this address depends on which NIC we use to
838 * route requests to the server.
840 * Returns one if successful, otherwise zero.
842 int clnt_ping(struct sockaddr_in *saddr, const unsigned long prog,
843 const unsigned long vers, const unsigned int prot,
844 struct sockaddr_in *caddr)
848 static char clnt_res;
849 struct sockaddr dissolve;
851 rpc_createerr.cf_stat = stat = 0;
852 sock = get_socket(saddr, prot, CONNECT_TIMEOUT, FALSE, TRUE);
853 if (sock == RPC_ANYSOCK) {
854 if (rpc_createerr.cf_error.re_errno == ETIMEDOUT) {
856 * TCP timeout. Bubble up the error to see
857 * how it should be handled.
859 rpc_createerr.cf_stat = RPC_TIMEDOUT;
865 /* Get the address of our end of this connection */
866 socklen_t len = sizeof(*caddr);
867 if (getsockname(sock, caddr, &len) != 0)
868 caddr->sin_family = 0;
873 /* The socket is connected (so we could getsockname successfully),
874 * but some servers on multi-homed hosts reply from
875 * the wrong address, so if we stay connected, we lose the reply.
877 dissolve.sa_family = AF_UNSPEC;
878 connect(sock, &dissolve, sizeof(dissolve));
880 clnt = clntudp_bufcreate(saddr, prog, vers,
881 RETRY_TIMEOUT, &sock,
882 RPCSMALLMSGSIZE, RPCSMALLMSGSIZE);
885 clnt = clnttcp_create(saddr, prog, vers, &sock,
886 RPCSMALLMSGSIZE, RPCSMALLMSGSIZE);
893 memset(&clnt_res, 0, sizeof(clnt_res));
894 stat = clnt_call(clnt, NULLPROC,
895 (xdrproc_t)xdr_void, (caddr_t)NULL,
896 (xdrproc_t)xdr_void, (caddr_t)&clnt_res,
899 clnt_geterr(clnt, &rpc_createerr.cf_error);
900 rpc_createerr.cf_stat = stat;
905 if (stat == RPC_SUCCESS)
912 * Try a getsockname() on a connected datagram socket.
914 * Returns 1 and fills in @buf if successful; otherwise, zero.
916 * A connected datagram socket prevents leaving a socket in TIME_WAIT.
917 * This conserves the ephemeral port number space, helping reduce failed
918 * socket binds during mount storms.
920 static int nfs_ca_sockname(const struct sockaddr *sap, const socklen_t salen,
921 struct sockaddr *buf, socklen_t *buflen)
923 struct sockaddr_in sin = {
924 .sin_family = AF_INET,
925 .sin_addr.s_addr = htonl(INADDR_ANY),
927 struct sockaddr_in6 sin6 = {
928 .sin6_family = AF_INET6,
929 .sin6_addr = IN6ADDR_ANY_INIT,
933 sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
937 switch (sap->sa_family) {
939 if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
945 if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) {
951 errno = EAFNOSUPPORT;
955 if (connect(sock, sap, salen) < 0) {
960 return !getsockname(sock, buf, buflen);
964 * Try to generate an address that prevents the server from calling us.
966 * Returns 1 and fills in @buf if successful; otherwise, zero.
968 static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t salen,
969 struct sockaddr *buf, socklen_t *buflen)
971 struct addrinfo *gai_results;
972 struct addrinfo gai_hint = {
973 .ai_family = sap->sa_family,
974 .ai_flags = AI_PASSIVE, /* ANYADDR */
977 if (getaddrinfo(NULL, "", &gai_hint, &gai_results))
980 *buflen = gai_results->ai_addrlen;
981 memcpy(buf, gai_results->ai_addr, *buflen);
983 freeaddrinfo(gai_results);
989 * nfs_callback_address - acquire our local network address
990 * @sap: pointer to address of remote
991 * @sap_len: length of address
992 * @buf: pointer to buffer to be filled in with local network address
993 * @buflen: IN: length of buffer to fill in; OUT: length of filled-in address
995 * Discover a network address that an NFSv4 server can use to call us back.
996 * On multi-homed clients, this address depends on which NIC we use to
997 * route requests to the server.
999 * Returns 1 and fills in @buf if an unambiguous local address is
1000 * available; returns 1 and fills in an appropriate ANYADDR address
1001 * if a local address isn't available; otherwise, returns zero.
1003 int nfs_callback_address(const struct sockaddr *sap, const socklen_t salen,
1004 struct sockaddr *buf, socklen_t *buflen)
1006 struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
1008 if (nfs_ca_sockname(sap, salen, buf, buflen) == 0)
1009 if (nfs_ca_gai(sap, salen, buf, buflen) == 0)
1013 * The server can't use an interface ID that was generated
1014 * here on the client, so always clear sin6_scope_id.
1016 if (sin6->sin6_family == AF_INET6)
1017 sin6->sin6_scope_id = 0;
1024 nfs_error(_("%s: failed to construct callback address"));