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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) 2002-2014 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;
if (initialised)
return addr_buf;
initialised = 1;
if (am_server) { /* daemon over --rsh mode */
char *env_str;
strlcpy(addr_buf, "0.0.0.0", sizeof addr_buf);
if ((env_str = getenv("REMOTE_HOST")) != NULL
|| (env_str = getenv("SSH_CONNECTION")) != NULL
|| (env_str = getenv("SSH_CLIENT")) != NULL
|| (env_str = getenv("SSH2_CLIENT")) != NULL) {
char *p;
strlcpy(addr_buf, env_str, 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;
}