canohost.c revision 323124 
1/* $OpenBSD: canohost.c,v 1.73 2016/03/07 19:02:43 djm Exp $ */
2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 *                    All rights reserved
6 * Functions for returning the canonical host name of the remote site.
7 *
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose.  Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
13 */
14
15#include "includes.h"
16
17#include <sys/types.h>
18#include <sys/socket.h>
19#include <sys/un.h>
20
21#include <netinet/in.h>
22#include <arpa/inet.h>
23
24#include <errno.h>
25#include <netdb.h>
26#include <stdio.h>
27#include <stdlib.h>
28#include <string.h>
29#include <stdarg.h>
30#include <unistd.h>
31
32#include "xmalloc.h"
33#include "packet.h"
34#include "log.h"
35#include "canohost.h"
36#include "misc.h"
37
38void
39ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len)
40{
41	struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr;
42	struct sockaddr_in *a4 = (struct sockaddr_in *)addr;
43	struct in_addr inaddr;
44	u_int16_t port;
45
46	if (addr->ss_family != AF_INET6 ||
47	    !IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr))
48		return;
49
50	debug3("Normalising mapped IPv4 in IPv6 address");
51
52	memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr));
53	port = a6->sin6_port;
54
55	memset(a4, 0, sizeof(*a4));
56
57	a4->sin_family = AF_INET;
58	*len = sizeof(*a4);
59	memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr));
60	a4->sin_port = port;
61}
62
63/*
64 * Returns the local/remote IP-address/hostname of socket as a string.
65 * The returned string must be freed.
66 */
67static char *
68get_socket_address(int sock, int remote, int flags)
69{
70	struct sockaddr_storage addr;
71	socklen_t addrlen;
72	char ntop[NI_MAXHOST];
73	int r;
74
75	/* Get IP address of client. */
76	addrlen = sizeof(addr);
77	memset(&addr, 0, sizeof(addr));
78
79	if (remote) {
80		if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) != 0)
81			return NULL;
82	} else {
83		if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) != 0)
84			return NULL;
85	}
86
87	/* Work around Linux IPv6 weirdness */
88	if (addr.ss_family == AF_INET6) {
89		addrlen = sizeof(struct sockaddr_in6);
90		ipv64_normalise_mapped(&addr, &addrlen);
91	}
92
93	switch (addr.ss_family) {
94	case AF_INET:
95	case AF_INET6:
96		/* Get the address in ascii. */
97		if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop,
98		    sizeof(ntop), NULL, 0, flags)) != 0) {
99			error("%s: getnameinfo %d failed: %s", __func__,
100			    flags, ssh_gai_strerror(r));
101			return NULL;
102		}
103		return xstrdup(ntop);
104	case AF_UNIX:
105		/* Get the Unix domain socket path. */
106		return xstrdup(((struct sockaddr_un *)&addr)->sun_path);
107	default:
108		/* We can't look up remote Unix domain sockets. */
109		return NULL;
110	}
111}
112
113char *
114get_peer_ipaddr(int sock)
115{
116	char *p;
117
118	if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL)
119		return p;
120	return xstrdup("UNKNOWN");
121}
122
123char *
124get_local_ipaddr(int sock)
125{
126	char *p;
127
128	if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL)
129		return p;
130	return xstrdup("UNKNOWN");
131}
132
133char *
134get_local_name(int fd)
135{
136	char *host, myname[NI_MAXHOST];
137
138	/* Assume we were passed a socket */
139	if ((host = get_socket_address(fd, 0, NI_NAMEREQD)) != NULL)
140		return host;
141
142	/* Handle the case where we were passed a pipe */
143	if (gethostname(myname, sizeof(myname)) == -1) {
144		verbose("%s: gethostname: %s", __func__, strerror(errno));
145		host = xstrdup("UNKNOWN");
146	} else {
147		host = xstrdup(myname);
148	}
149
150	return host;
151}
152
153/* Returns the local/remote port for the socket. */
154
155static int
156get_sock_port(int sock, int local)
157{
158	struct sockaddr_storage from;
159	socklen_t fromlen;
160	char strport[NI_MAXSERV];
161	int r;
162
163	/* Get IP address of client. */
164	fromlen = sizeof(from);
165	memset(&from, 0, sizeof(from));
166	if (local) {
167		if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
168			error("getsockname failed: %.100s", strerror(errno));
169			return 0;
170		}
171	} else {
172		if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
173			debug("getpeername failed: %.100s", strerror(errno));
174			return -1;
175		}
176	}
177
178	/* Work around Linux IPv6 weirdness */
179	if (from.ss_family == AF_INET6)
180		fromlen = sizeof(struct sockaddr_in6);
181
182	/* Non-inet sockets don't have a port number. */
183	if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
184		return 0;
185
186	/* Return port number. */
187	if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
188	    strport, sizeof(strport), NI_NUMERICSERV)) != 0)
189		fatal("%s: getnameinfo NI_NUMERICSERV failed: %s", __func__,
190		    ssh_gai_strerror(r));
191	return atoi(strport);
192}
193
194int
195get_peer_port(int sock)
196{
197	return get_sock_port(sock, 0);
198}
199
200int
201get_local_port(int sock)
202{
203	return get_sock_port(sock, 1);
204}
205