xref: /openssh-portable/canohost.c (revision 816036f1)
1 /* $OpenBSD: canohost.c,v 1.75 2020/10/18 11:32:01 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 
38 void
ipv64_normalise_mapped(struct sockaddr_storage * addr,socklen_t * len)39 ipv64_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  */
67 static char *
get_socket_address(int sock,int remote,int flags)68 get_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_f("getnameinfo %d failed: %s",
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 
113 char *
get_peer_ipaddr(int sock)114 get_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 
123 char *
get_local_ipaddr(int sock)124 get_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 
133 char *
get_local_name(int fd)134 get_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_f("gethostname: %s", 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 
155 static int
get_sock_port(int sock,int local)156 get_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) == -1) {
168 			error("getsockname failed: %.100s", strerror(errno));
169 			return 0;
170 		}
171 	} else {
172 		if (getpeername(sock, (struct sockaddr *)&from, &fromlen) == -1) {
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_f("getnameinfo NI_NUMERICSERV failed: %s",
190 		    ssh_gai_strerror(r));
191 	return atoi(strport);
192 }
193 
194 int
get_peer_port(int sock)195 get_peer_port(int sock)
196 {
197 	return get_sock_port(sock, 0);
198 }
199 
200 int
get_local_port(int sock)201 get_local_port(int sock)
202 {
203 	return get_sock_port(sock, 1);
204 }
205