303 lines
8.6 KiB
C
303 lines
8.6 KiB
C
/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Functions for returning the canonical host name of the remote site.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*/
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#include "includes.h"
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RCSID("$OpenBSD: canohost.c,v 1.15 2000/09/07 21:13:37 markus Exp $");
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RCSID("$FreeBSD$");
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#include "packet.h"
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#include "xmalloc.h"
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#include "ssh.h"
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/*
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* Return the canonical name of the host at the other end of the socket. The
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* caller should free the returned string with xfree.
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*/
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char *
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get_remote_hostname(int socket)
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{
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struct sockaddr_storage from;
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int i;
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socklen_t fromlen;
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struct addrinfo hints, *ai, *aitop;
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char name[MAXHOSTNAMELEN];
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char ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
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/* Get IP address of client. */
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fromlen = sizeof(from);
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memset(&from, 0, sizeof(from));
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if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
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debug("getpeername failed: %.100s", strerror(errno));
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fatal_cleanup();
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}
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if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
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NULL, 0, NI_NUMERICHOST) != 0)
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fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
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/* Map the IP address to a host name. */
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if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
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NULL, 0, NI_NAMEREQD) == 0) {
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/* Got host name. */
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name[sizeof(name) - 1] = '\0';
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/*
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* Convert it to all lowercase (which is expected by the rest
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* of this software).
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*/
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for (i = 0; name[i]; i++)
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if (isupper(name[i]))
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name[i] = tolower(name[i]);
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/*
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* Map it back to an IP address and check that the given
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* address actually is an address of this host. This is
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* necessary because anyone with access to a name server can
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* define arbitrary names for an IP address. Mapping from
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* name to IP address can be trusted better (but can still be
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* fooled if the intruder has access to the name server of
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* the domain).
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*/
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = from.ss_family;
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hints.ai_socktype = SOCK_STREAM;
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if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
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log("reverse mapping checking getaddrinfo for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name);
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strlcpy(name, ntop, sizeof name);
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goto check_ip_options;
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}
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/* Look for the address from the list of addresses. */
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for (ai = aitop; ai; ai = ai->ai_next) {
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if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
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sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
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(strcmp(ntop, ntop2) == 0))
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break;
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}
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freeaddrinfo(aitop);
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/* If we reached the end of the list, the address was not there. */
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if (!ai) {
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/* Address not found for the host name. */
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log("Address %.100s maps to %.600s, but this does not map back to the address - POSSIBLE BREAKIN ATTEMPT!",
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ntop, name);
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strlcpy(name, ntop, sizeof name);
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goto check_ip_options;
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}
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/* Address was found for the host name. We accept the host name. */
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} else {
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/* Host name not found. Use ascii representation of the address. */
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strlcpy(name, ntop, sizeof name);
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log("Could not reverse map address %.100s.", name);
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}
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check_ip_options:
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/*
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* If IP options are supported, make sure there are none (log and
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* disconnect them if any are found). Basically we are worried about
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* source routing; it can be used to pretend you are somebody
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* (ip-address) you are not. That itself may be "almost acceptable"
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* under certain circumstances, but rhosts autentication is useless
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* if source routing is accepted. Notice also that if we just dropped
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* source routing here, the other side could use IP spoofing to do
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* rest of the interaction and could still bypass security. So we
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* exit here if we detect any IP options.
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*/
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/* IP options -- IPv4 only */
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if (from.ss_family == AF_INET) {
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unsigned char options[200], *ucp;
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char text[1024], *cp;
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socklen_t option_size;
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int ipproto;
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struct protoent *ip;
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if ((ip = getprotobyname("ip")) != NULL)
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ipproto = ip->p_proto;
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else
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ipproto = IPPROTO_IP;
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option_size = sizeof(options);
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if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options,
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&option_size) >= 0 && option_size != 0) {
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cp = text;
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/* Note: "text" buffer must be at least 3x as big as options. */
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for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
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sprintf(cp, " %2.2x", *ucp);
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log("Connection from %.100s with IP options:%.800s",
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ntop, text);
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packet_disconnect("Connection from %.100s with IP options:%.800s",
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ntop, text);
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}
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}
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return xstrdup(name);
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}
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/*
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* Return the canonical name of the host in the other side of the current
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* connection. The host name is cached, so it is efficient to call this
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* several times.
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*/
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const char *
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get_canonical_hostname()
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{
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static char *canonical_host_name = NULL;
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/* Check if we have previously retrieved this same name. */
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if (canonical_host_name != NULL)
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return canonical_host_name;
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/* Get the real hostname if socket; otherwise return UNKNOWN. */
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if (packet_connection_is_on_socket())
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canonical_host_name = get_remote_hostname(packet_get_connection_in());
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else
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canonical_host_name = xstrdup("UNKNOWN");
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return canonical_host_name;
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}
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/*
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* Returns the IP-address of the remote host as a string. The returned
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* string must not be freed.
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*/
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const char *
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get_remote_ipaddr()
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{
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static char *canonical_host_ip = NULL;
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struct sockaddr_storage from;
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socklen_t fromlen;
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int socket;
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char ntop[NI_MAXHOST];
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/* Check whether we have chached the name. */
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if (canonical_host_ip != NULL)
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return canonical_host_ip;
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/* If not a socket, return UNKNOWN. */
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if (!packet_connection_is_on_socket()) {
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canonical_host_ip = xstrdup("UNKNOWN");
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return canonical_host_ip;
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}
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/* Get client socket. */
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socket = packet_get_connection_in();
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/* Get IP address of client. */
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fromlen = sizeof(from);
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memset(&from, 0, sizeof(from));
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if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
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debug("getpeername failed: %.100s", strerror(errno));
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fatal_cleanup();
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}
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/* Get the IP address in ascii. */
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if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
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NULL, 0, NI_NUMERICHOST) != 0)
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fatal("get_remote_ipaddr: getnameinfo NI_NUMERICHOST failed");
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canonical_host_ip = xstrdup(ntop);
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/* Return ip address string. */
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return canonical_host_ip;
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}
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/*
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* Returns the IP-address of the local host as a string. The returned
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* string must be freed.
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*/
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const char *
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get_ipaddr(int socket)
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{
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static char *canonical_host_ip = NULL;
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struct sockaddr_storage from;
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socklen_t fromlen;
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char ntop[NI_MAXHOST];
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/* Get IP address of server. */
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fromlen = sizeof(from);
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memset(&from, 0, sizeof(from));
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if (getsockname(socket, (struct sockaddr *)&from, &fromlen) < 0) {
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debug("getsockname failed: %.100s", strerror(errno));
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fatal_cleanup();
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}
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/* Get the IP address in ascii. */
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if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
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NULL, 0, NI_NUMERICHOST) != 0)
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fatal("get_local_ipaddr: getnameinfo NI_NUMERICHOST failed");
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/* Return ip address string. */
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return xstrdup(ntop);
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}
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/* Returns the local/remote port for the socket. */
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int
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get_sock_port(int sock, int local)
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{
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struct sockaddr_storage from;
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socklen_t fromlen;
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char strport[NI_MAXSERV];
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/* Get IP address of client. */
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fromlen = sizeof(from);
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memset(&from, 0, sizeof(from));
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if (local) {
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if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
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error("getsockname failed: %.100s", strerror(errno));
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return 0;
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}
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} else {
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if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
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debug("getpeername failed: %.100s", strerror(errno));
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fatal_cleanup();
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}
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}
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/* Return port number. */
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if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
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strport, sizeof(strport), NI_NUMERICSERV) != 0)
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fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
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return atoi(strport);
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}
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/* Returns remote/local port number for the current connection. */
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int
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get_port(int local)
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{
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/*
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* If the connection is not a socket, return 65535. This is
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* intentionally chosen to be an unprivileged port number.
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*/
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if (!packet_connection_is_on_socket())
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return 65535;
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/* Get socket and return the port number. */
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return get_sock_port(packet_get_connection_in(), local);
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}
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int
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get_peer_port(int sock)
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{
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return get_sock_port(sock, 0);
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}
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int
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get_remote_port()
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{
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return get_port(0);
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}
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int
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get_local_port()
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{
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return get_port(1);
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}
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