1 /*-
2 * Copyright (c) 2010 Bjoern A. Zeeb <bz@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD$
27 */
28
29 #ifdef HAVE_CONFIG_H
30 #include "config.h"
31 #else
32 #include "default_config.h"
33 #endif
34
35 #include <string.h>
36 #ifndef WIN32
37 # include <sys/types.h>
38 # include <sys/socket.h>
39 #include <netinet/in.h>
40 #else
41 # include <winsock2.h>
42 # include <ws2tcpip.h> /*sockaddr, addrinfo etc.*/
43 # include <stdint.h>
44 #endif /*WIN32*/
45
46 #include "pcp.h"
47 #include "findsaddr.h"
48 #include "unp.h"
49
50 /*
51 * Return the source address for the given destination address.
52 *
53 * This makes use of proper source address selection in the FreeBSD kernel
54 * even taking jails into account (sys/netinet/in_pcb.c:in_pcbladdr()).
55 * We open a UDP socket, and connect to the destination, letting the kernel
56 * do the bind and then read the source IPv4 address using getsockname(2).
57 * This has multiple advantages: no need to do PF_ROUTE operations possibly
58 * needing special privileges, jails properly taken into account and most
59 * important - getting the result the kernel would give us rather than
60 * best-guessing ourselves.
61 */
62
63 #ifndef SOCKET
64 #define SOCKET int
65 #endif
66
67 #ifndef INVALID_SOCKET
68 #define INVALID_SOCKET -1
69 #endif
70
findsaddr(register const struct sockaddr_in * to,struct in6_addr * from)71 const char *findsaddr(register const struct sockaddr_in *to,
72 struct in6_addr *from)
73 {
74 const char *errstr;
75 struct sockaddr_in cto, cfrom;
76 SOCKET s;
77 socklen_t len;
78
79 s=socket(AF_INET, SOCK_DGRAM, 0);
80 if (s == INVALID_SOCKET)
81 return ("failed to open DGRAM socket for src addr selection.");
82 errstr=NULL;
83 len=sizeof(struct sockaddr_in);
84 memcpy(&cto, to, len);
85 cto.sin_port=htons(65535); /* Dummy port for connect(2). */
86 if (connect(s, (struct sockaddr *)&cto, len) == -1) {
87 errstr="failed to connect to peer for src addr selection.";
88 goto err;
89 }
90
91 if (getsockname(s, (struct sockaddr *)&cfrom, &len) == -1) {
92 errstr="failed to get socket name for src addr selection.";
93 goto err;
94 }
95
96 if (len != sizeof(struct sockaddr_in) || cfrom.sin_family != AF_INET) {
97 errstr="unexpected address family in src addr selection.";
98 goto err;
99 }
100
101 ((uint32_t *)from)[0]=0;
102 ((uint32_t *)from)[1]=0;
103 ((uint32_t *)from)[2]=htonl(0xffff);
104 ((uint32_t *)from)[3]=cfrom.sin_addr.s_addr;
105
106 err:
107 (void)CLOSE(s);
108
109 /* No error (string) to return. */
110 return (errstr);
111 }
112
findsaddr6(register const struct sockaddr_in6 * to,register struct in6_addr * from)113 const char *findsaddr6(register const struct sockaddr_in6 *to,
114 register struct in6_addr *from)
115 {
116 const char *errstr;
117 struct sockaddr_in6 cto, cfrom;
118 SOCKET s;
119 socklen_t len;
120 uint32_t sock_flg=0;
121
122 if (IN6_IS_ADDR_LOOPBACK(&to->sin6_addr)) {
123 memcpy(from, &to->sin6_addr, sizeof(struct in6_addr));
124 return NULL;
125 }
126
127 s=socket(AF_INET6, SOCK_DGRAM, 0);
128 if (s == INVALID_SOCKET)
129 return ("failed to open DGRAM socket for src addr selection.");
130
131 errstr=NULL;
132
133 //Enable Dual-stack socket for Vista and higher
134 if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, (char *)&sock_flg,
135 sizeof(sock_flg)) == -1) {
136 errstr="setsockopt failed to set dual stack mode.";
137 goto err;
138 }
139
140 len=sizeof(struct sockaddr_in6);
141 memcpy(&cto, to, len);
142 cto.sin6_port=htons(65535); /* Dummy port for connect(2). */
143 if (connect(s, (struct sockaddr *)&cto, len) == -1) {
144 errstr="failed to connect to peer for src addr selection.";
145 goto err;
146 }
147
148 if (getsockname(s, (struct sockaddr *)&cfrom, &len) == -1) {
149 errstr="failed to get socket name for src addr selection.";
150 goto err;
151 }
152
153 if (len != sizeof(struct sockaddr_in6) || cfrom.sin6_family != AF_INET6) {
154 errstr="unexpected address family in src addr selection.";
155 goto err;
156 }
157
158 memcpy(from->s6_addr, cfrom.sin6_addr.s6_addr, sizeof(struct in6_addr));
159
160 err:
161 (void) CLOSE(s);
162
163 /* No error (string) to return. */
164 return (errstr);
165 }
166
167 /* end */
168