RepoMirrors
/
openssh
mirror of git://anongit.mindrot.org/openssh.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
openssh/canohost.c

299 lines
8.2 KiB
C
Raw Blame History

/*
*
* canohost.c
*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*
* Created: Sun Jul 2 17:52:22 1995 ylo
*
* Functions for returning the canonical host name of the remote site.
*
*/
#include "includes.h"
RCSID("$Id: canohost.c,v 1.9 2000/04/16 01:18:40 damien Exp $");
#include "packet.h"
#include "xmalloc.h"
#include "ssh.h"
/*
* Return the canonical name of the host at the other end of the socket. The
* caller should free the returned string with xfree.
*/
char *
get_remote_hostname(int socket)
{
struct sockaddr_storage from;
int i;
socklen_t fromlen;
struct addrinfo hints, *ai, *aitop;
char name[MAXHOSTNAMELEN];
char ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
/* Get IP address of client. */
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
debug("getpeername failed: %.100s", strerror(errno));
fatal_cleanup();
}
#ifdef IPV4_IN_IPV6
if (from.ss_family == AF_INET6) {
struct sockaddr_in6 *from6 = (struct sockaddr_in6 *)&from;
/* Detect IPv4 in IPv6 mapped address and convert it to */
/* plain (AF_INET) IPv4 address */
if (IN6_IS_ADDR_V4MAPPED(&from6->sin6_addr)) {
struct sockaddr_in *from4 = (struct sockaddr_in *)&from;
struct in_addr addr;
u_int16_t port;
memcpy(&addr, ((char *)&from6->sin6_addr) + 12, sizeof(addr));
port = from6->sin6_port;
memset(&from, 0, sizeof(from));
from4->sin_family = AF_INET;
memcpy(&from4->sin_addr, &addr, sizeof(addr));
from4->sin_port = port;
}
}
#endif
if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
NULL, 0, NI_NUMERICHOST) != 0)
fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
/* Map the IP address to a host name. */
if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
NULL, 0, NI_NAMEREQD) == 0) {
/* Got host name. */
name[sizeof(name) - 1] = '\0';
/*
* Convert it to all lowercase (which is expected by the rest
* of this software).
*/
for (i = 0; name[i]; i++)
if (isupper(name[i]))
name[i] = tolower(name[i]);
/*
* Map it back to an IP address and check that the given
* address actually is an address of this host. This is
* necessary because anyone with access to a name server can
* define arbitrary names for an IP address. Mapping from
* name to IP address can be trusted better (but can still be
* fooled if the intruder has access to the name server of
* the domain).
*/
memset(&hints, 0, sizeof(hints));
hints.ai_family = from.ss_family;
hints.ai_socktype = SOCK_STREAM;
if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
log("reverse mapping checking getaddrinfo for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name);
strlcpy(name, ntop, sizeof name);
goto check_ip_options;
}
/* Look for the address from the list of addresses. */
for (ai = aitop; ai; ai = ai->ai_next) {
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
(strcmp(ntop, ntop2) == 0))
break;
}
freeaddrinfo(aitop);
/* If we reached the end of the list, the address was not there. */
if (!ai) {
/* Address not found for the host name. */
log("Address %.100s maps to %.600s, but this does not map back to the address - POSSIBLE BREAKIN ATTEMPT!",
ntop, name);
strlcpy(name, ntop, sizeof name);
goto check_ip_options;
}
/* Address was found for the host name. We accept the host name. */
} else {
/* Host name not found. Use ascii representation of the address. */
strlcpy(name, ntop, sizeof name);
log("Could not reverse map address %.100s.", name);
}
check_ip_options:
/*
* If IP options are supported, make sure there are none (log and
* disconnect them if any are found). Basically we are worried about
* source routing; it can be used to pretend you are somebody
* (ip-address) you are not. That itself may be "almost acceptable"
* under certain circumstances, but rhosts autentication is useless
* if source routing is accepted. Notice also that if we just dropped
* source routing here, the other side could use IP spoofing to do
* rest of the interaction and could still bypass security. So we
* exit here if we detect any IP options.
*/
/* IP options -- IPv4 only */
if (from.ss_family == AF_INET) {
unsigned char options[200], *ucp;
char text[1024], *cp;
socklen_t option_size;
int ipproto;
struct protoent *ip;
if ((ip = getprotobyname("ip")) != NULL)
ipproto = ip->p_proto;
else
ipproto = IPPROTO_IP;
option_size = sizeof(options);
if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options,
&option_size) >= 0 && option_size != 0) {
cp = text;
/* Note: "text" buffer must be at least 3x as big as options. */
for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
sprintf(cp, " %2.2x", *ucp);
log("Connection from %.100s with IP options:%.800s",
ntop, text);
packet_disconnect("Connection from %.100s with IP options:%.800s",
ntop, text);
}
}
return xstrdup(name);
}
/*
* Return the canonical name of the host in the other side of the current
* connection. The host name is cached, so it is efficient to call this
* several times.
*/
const char *
get_canonical_hostname()
{
static char *canonical_host_name = NULL;
/* Check if we have previously retrieved this same name. */
if (canonical_host_name != NULL)
return canonical_host_name;
/* Get the real hostname if socket; otherwise return UNKNOWN. */
if (packet_connection_is_on_socket())
canonical_host_name = get_remote_hostname(packet_get_connection_in());
else
canonical_host_name = xstrdup("UNKNOWN");
return canonical_host_name;
}
/*
* Returns the IP-address of the remote host as a string. The returned
* string must not be freed.
*/
const char *
get_remote_ipaddr()
{
static char *canonical_host_ip = NULL;
struct sockaddr_storage from;
socklen_t fromlen;
int socket;
char ntop[NI_MAXHOST];
/* Check whether we have chached the name. */
if (canonical_host_ip != NULL)
return canonical_host_ip;
/* If not a socket, return UNKNOWN. */
if (!packet_connection_is_on_socket()) {
canonical_host_ip = xstrdup("UNKNOWN");
return canonical_host_ip;
}
/* Get client socket. */
socket = packet_get_connection_in();
/* Get IP address of client. */
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
debug("getpeername failed: %.100s", strerror(errno));
fatal_cleanup();
}
/* Get the IP address in ascii. */
if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
NULL, 0, NI_NUMERICHOST) != 0)
fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
canonical_host_ip = xstrdup(ntop);
/* Return ip address string. */
return canonical_host_ip;
}
/* Returns the local/remote port for the socket. */
int
get_sock_port(int sock, int local)
{
struct sockaddr_storage from;
socklen_t fromlen;
char strport[NI_MAXSERV];
/* Get IP address of client. */
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
if (local) {
if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
error("getsockname failed: %.100s", strerror(errno));
return 0;
}
} else {
if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
debug("getpeername failed: %.100s", strerror(errno));
fatal_cleanup();
}
}
/* Return port number. */
if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
strport, sizeof(strport), NI_NUMERICSERV) != 0)
fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
return atoi(strport);
}
/* Returns remote/local port number for the current connection. */
int
get_port(int local)
{
/*
* If the connection is not a socket, return 65535. This is
* intentionally chosen to be an unprivileged port number.
*/
if (!packet_connection_is_on_socket())
return 65535;
/* Get socket and return the port number. */
return get_sock_port(packet_get_connection_in(), local);
}
int
get_peer_port(int sock)
{
return get_sock_port(sock, 0);
}
int
get_remote_port()
{
return get_port(0);
}
int
get_local_port()
{
return get_port(1);
}
Reference in New Issue View Git Blame Copy Permalink