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- /*
- * Functions for looking up the remote name or addr of a socket.
- *
- * Copyright (C) 1992-2001 Andrew Tridgell <tridge@samba.org>
- * Copyright (C) 2001, 2002 Martin Pool <mbp@samba.org>
- * Copyright (C) 2002-2009 Wayne Davison
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, visit the http://fsf.org website.
- */
- /*
- * This file is now converted to use the new-style getaddrinfo()
- * interface, which supports IPv6 but is also supported on recent
- * IPv4-only machines. On systems that don't have that interface, we
- * emulate it using the KAME implementation.
- */
- #include "rsync.h"
- static const char default_name[] = "UNKNOWN";
- extern int am_server;
- /**
- * Return the IP addr of the client as a string
- **/
- char *client_addr(int fd)
- {
- static char addr_buf[100];
- static int initialised;
- struct sockaddr_storage ss;
- socklen_t length = sizeof ss;
- char *ssh_info, *p;
- if (initialised)
- return addr_buf;
- initialised = 1;
- if (am_server) { /* daemon over --rsh mode */
- strlcpy(addr_buf, "0.0.0.0", sizeof addr_buf);
- if ((ssh_info = getenv("SSH_CONNECTION")) != NULL
- || (ssh_info = getenv("SSH_CLIENT")) != NULL
- || (ssh_info = getenv("SSH2_CLIENT")) != NULL) {
- strlcpy(addr_buf, ssh_info, sizeof addr_buf);
- /* Truncate the value to just the IP address. */
- if ((p = strchr(addr_buf, ' ')) != NULL)
- *p = '\0';
- }
- } else {
- client_sockaddr(fd, &ss, &length);
- getnameinfo((struct sockaddr *)&ss, length,
- addr_buf, sizeof addr_buf, NULL, 0, NI_NUMERICHOST);
- }
- return addr_buf;
- }
- static int get_sockaddr_family(const struct sockaddr_storage *ss)
- {
- return ((struct sockaddr *) ss)->sa_family;
- }
- /**
- * Return the DNS name of the client.
- *
- * The name is statically cached so that repeated lookups are quick,
- * so there is a limit of one lookup per customer.
- *
- * If anything goes wrong, including the name->addr->name check, then
- * we just use "UNKNOWN", so you can use that value in hosts allow
- * lines.
- *
- * After translation from sockaddr to name we do a forward lookup to
- * make sure nobody is spoofing PTR records.
- **/
- char *client_name(int fd)
- {
- static char name_buf[100];
- static char port_buf[100];
- static int initialised;
- struct sockaddr_storage ss;
- socklen_t ss_len;
- if (initialised)
- return name_buf;
- strlcpy(name_buf, default_name, sizeof name_buf);
- initialised = 1;
- memset(&ss, 0, sizeof ss);
- if (am_server) { /* daemon over --rsh mode */
- char *addr = client_addr(fd);
- struct addrinfo hint, *answer;
- int err;
- if (strcmp(addr, "0.0.0.0") == 0)
- return name_buf;
- memset(&hint, 0, sizeof hint);
- #ifdef AI_NUMERICHOST
- hint.ai_flags = AI_NUMERICHOST;
- #endif
- hint.ai_socktype = SOCK_STREAM;
- if ((err = getaddrinfo(addr, NULL, &hint, &answer)) != 0) {
- rprintf(FLOG, "malformed address %s: %s\n",
- addr, gai_strerror(err));
- return name_buf;
- }
- switch (answer->ai_family) {
- case AF_INET:
- ss_len = sizeof (struct sockaddr_in);
- memcpy(&ss, answer->ai_addr, ss_len);
- break;
- #ifdef INET6
- case AF_INET6:
- ss_len = sizeof (struct sockaddr_in6);
- memcpy(&ss, answer->ai_addr, ss_len);
- break;
- #endif
- default:
- exit_cleanup(RERR_SOCKETIO);
- }
- freeaddrinfo(answer);
- } else {
- ss_len = sizeof ss;
- client_sockaddr(fd, &ss, &ss_len);
- }
- if (lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf,
- port_buf, sizeof port_buf) == 0)
- check_name(fd, &ss, name_buf, sizeof name_buf);
- return name_buf;
- }
- /**
- * Get the sockaddr for the client.
- *
- * If it comes in as an ipv4 address mapped into IPv6 format then we
- * convert it back to a regular IPv4.
- **/
- void client_sockaddr(int fd,
- struct sockaddr_storage *ss,
- socklen_t *ss_len)
- {
- memset(ss, 0, sizeof *ss);
- if (getpeername(fd, (struct sockaddr *) ss, ss_len)) {
- /* FIXME: Can we really not continue? */
- rsyserr(FLOG, errno, "getpeername on fd%d failed", fd);
- exit_cleanup(RERR_SOCKETIO);
- }
- #ifdef INET6
- if (get_sockaddr_family(ss) == AF_INET6 &&
- IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) {
- /* OK, so ss is in the IPv6 family, but it is really
- * an IPv4 address: something like
- * "::ffff:10.130.1.2". If we use it as-is, then the
- * reverse lookup might fail or perhaps something else
- * bad might happen. So instead we convert it to an
- * equivalent address in the IPv4 address family. */
- struct sockaddr_in6 sin6;
- struct sockaddr_in *sin;
- memcpy(&sin6, ss, sizeof sin6);
- sin = (struct sockaddr_in *)ss;
- memset(sin, 0, sizeof *sin);
- sin->sin_family = AF_INET;
- *ss_len = sizeof (struct sockaddr_in);
- #ifdef HAVE_SOCKADDR_IN_LEN
- sin->sin_len = *ss_len;
- #endif
- sin->sin_port = sin6.sin6_port;
- /* There is a macro to extract the mapped part
- * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem
- * to be present in the Linux headers. */
- memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12],
- sizeof sin->sin_addr);
- }
- #endif
- }
- /**
- * Look up a name from @p ss into @p name_buf.
- *
- * @param fd file descriptor for client socket.
- **/
- int lookup_name(int fd, const struct sockaddr_storage *ss,
- socklen_t ss_len,
- char *name_buf, size_t name_buf_size,
- char *port_buf, size_t port_buf_size)
- {
- int name_err;
- /* reverse lookup */
- name_err = getnameinfo((struct sockaddr *) ss, ss_len,
- name_buf, name_buf_size,
- port_buf, port_buf_size,
- NI_NAMEREQD | NI_NUMERICSERV);
- if (name_err != 0) {
- strlcpy(name_buf, default_name, name_buf_size);
- rprintf(FLOG, "name lookup failed for %s: %s\n",
- client_addr(fd), gai_strerror(name_err));
- return name_err;
- }
- return 0;
- }
- /**
- * Compare an addrinfo from the resolver to a sockinfo.
- *
- * Like strcmp, returns 0 for identical.
- **/
- int compare_addrinfo_sockaddr(const struct addrinfo *ai,
- const struct sockaddr_storage *ss)
- {
- int ss_family = get_sockaddr_family(ss);
- const char fn[] = "compare_addrinfo_sockaddr";
- if (ai->ai_family != ss_family) {
- rprintf(FLOG, "%s: response family %d != %d\n",
- fn, ai->ai_family, ss_family);
- return 1;
- }
- /* The comparison method depends on the particular AF. */
- if (ss_family == AF_INET) {
- const struct sockaddr_in *sin1, *sin2;
- sin1 = (const struct sockaddr_in *) ss;
- sin2 = (const struct sockaddr_in *) ai->ai_addr;
- return memcmp(&sin1->sin_addr, &sin2->sin_addr,
- sizeof sin1->sin_addr);
- }
- #ifdef INET6
- if (ss_family == AF_INET6) {
- const struct sockaddr_in6 *sin1, *sin2;
- sin1 = (const struct sockaddr_in6 *) ss;
- sin2 = (const struct sockaddr_in6 *) ai->ai_addr;
- if (ai->ai_addrlen < sizeof (struct sockaddr_in6)) {
- rprintf(FLOG, "%s: too short sockaddr_in6; length=%d\n",
- fn, (int)ai->ai_addrlen);
- return 1;
- }
- if (memcmp(&sin1->sin6_addr, &sin2->sin6_addr,
- sizeof sin1->sin6_addr))
- return 1;
- #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID
- if (sin1->sin6_scope_id != sin2->sin6_scope_id)
- return 1;
- #endif
- return 0;
- }
- #endif /* INET6 */
- /* don't know */
- return 1;
- }
- /**
- * Do a forward lookup on @p name_buf and make sure it corresponds to
- * @p ss -- otherwise we may be being spoofed. If we suspect we are,
- * then we don't abort the connection but just emit a warning, and
- * change @p name_buf to be "UNKNOWN".
- *
- * We don't do anything with the service when checking the name,
- * because it doesn't seem that it could be spoofed in any way, and
- * getaddrinfo on random service names seems to cause problems on AIX.
- **/
- int check_name(int fd,
- const struct sockaddr_storage *ss,
- char *name_buf, size_t name_buf_size)
- {
- struct addrinfo hints, *res, *res0;
- int error;
- int ss_family = get_sockaddr_family(ss);
- memset(&hints, 0, sizeof hints);
- hints.ai_family = ss_family;
- hints.ai_flags = AI_CANONNAME;
- hints.ai_socktype = SOCK_STREAM;
- error = getaddrinfo(name_buf, NULL, &hints, &res0);
- if (error) {
- rprintf(FLOG, "forward name lookup for %s failed: %s\n",
- name_buf, gai_strerror(error));
- strlcpy(name_buf, default_name, name_buf_size);
- return error;
- }
- /* Given all these results, we expect that one of them will be
- * the same as ss. The comparison is a bit complicated. */
- for (res = res0; res; res = res->ai_next) {
- if (!compare_addrinfo_sockaddr(res, ss))
- break; /* OK, identical */
- }
- if (!res0) {
- /* We hit the end of the list without finding an
- * address that was the same as ss. */
- rprintf(FLOG, "no known address for \"%s\": "
- "spoofed address?\n", name_buf);
- strlcpy(name_buf, default_name, name_buf_size);
- } else if (res == NULL) {
- /* We hit the end of the list without finding an
- * address that was the same as ss. */
- rprintf(FLOG, "%s is not a known address for \"%s\": "
- "spoofed address?\n", client_addr(fd), name_buf);
- strlcpy(name_buf, default_name, name_buf_size);
- }
- freeaddrinfo(res0);
- return 0;
- }
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