/* -*- c-file-style: "linux" -*- rsync -- fast file replication program Copyright (C) 1992-2001 by Andrew Tridgell Copyright (C) 2001, 2002 by Martin Pool 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 2 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, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /** * @file clientname.c * * Functions for looking up the remote name or addr of a socket. * * 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"; /** * Return the IP addr of the client as a string **/ char *client_addr(int fd) { struct sockaddr_storage ss; socklen_t length = sizeof ss; static char addr_buf[100]; static int initialised; if (initialised) return addr_buf; initialised = 1; 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. **/ char *client_name(int fd) { struct sockaddr_storage ss; socklen_t ss_len = sizeof ss; static char name_buf[100]; static char port_buf[100]; static int initialised; if (initialised) return name_buf; strcpy(name_buf, default_name); initialised = 1; client_sockaddr(fd, &ss, &ss_len); if (!lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf, port_buf, sizeof port_buf)) check_name(fd, &ss, ss_len, name_buf, port_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) { if (getpeername(fd, (struct sockaddr *) ss, ss_len)) { /* FIXME: Can we really not continue? */ rprintf(FERROR, RSYNC_NAME ": getpeername on fd%d failed: %s\n", fd, strerror(errno)); 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_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. **/ int lookup_name(int fd, const struct sockaddr_storage *ss, socklen_t ss_len, char *name_buf, size_t name_buf_len, char *port_buf, size_t port_buf_len) { int name_err; /* reverse lookup */ name_err = getnameinfo((struct sockaddr *) ss, ss_len, name_buf, name_buf_len, port_buf, port_buf_len, NI_NAMEREQD | NI_NUMERICSERV); if (name_err != 0) { strcpy(name_buf, default_name); rprintf(FERROR, RSYNC_NAME ": 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"; size_t valid_len; if (ai->ai_family != ss_family) { rprintf(FERROR, "%s: response family %d != %d\n", fn, ai->ai_family, ss_family); return 1; } switch (ss_family) { case AF_INET: valid_len = sizeof (struct sockaddr_in); break; #ifdef INET6 case AF_INET6: valid_len = sizeof (struct sockaddr_in6); break; #endif default: /* Don't know what to do! */ return 1; } return memcmp(ss, ai->ai_addr, valid_len); } /** * 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". **/ int check_name(int fd, const struct sockaddr_storage *ss, socklen_t ss_len, char *name_buf, const char *port_buf) { struct addrinfo hints, *res, *res0; int error; int ss_family = get_sockaddr_family(ss); memset(&hints, 0, sizeof(hints)); hints.ai_family = PF_UNSPEC; hints.ai_flags = ss_family; hints.ai_socktype = SOCK_STREAM; error = getaddrinfo(name_buf, port_buf, &hints, &res0); if (error) { rprintf(FERROR, RSYNC_NAME ": forward name lookup for %s failed: %s\n", name_buf, gai_strerror(error)); strcpy(name_buf, default_name); 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(FERROR, RSYNC_NAME ": no known address for \"%s\": " "spoofed address?\n", name_buf); strcpy(name_buf, default_name); } else if (res == NULL) { /* We hit the end of the list without finding an * address that was the same as ss. */ rprintf(FERROR, RSYNC_NAME ": %s is not a known address for \"%s\": " "spoofed address?\n", client_addr(fd), name_buf); strcpy(name_buf, default_name); } freeaddrinfo(res0); return 0; }