1 /* $OpenBSD: bindresvport.c,v 1.19 2019/06/28 13:32:42 deraadt Exp $ */
2
3 /*
4 * Copyright 1996, Jason Downs. All rights reserved.
5 * Copyright 1998, Theo de Raadt. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <errno.h>
29 #include <string.h>
30 #include <sys/types.h>
31 #include <sys/socket.h>
32 #include <netinet/in.h>
33
34 /*
35 * Bind a socket to a privileged IP port
36 */
37 int
bindresvport(int sd,struct sockaddr_in * sin)38 bindresvport(int sd, struct sockaddr_in *sin)
39 {
40 return bindresvport_sa(sd, (struct sockaddr *)sin);
41 }
42 DEF_WEAK(bindresvport);
43
44 /*
45 * Bind a socket to a privileged port for whatever protocol.
46 */
47 int
bindresvport_sa(int sd,struct sockaddr * sa)48 bindresvport_sa(int sd, struct sockaddr *sa)
49 {
50 int old, error, af;
51 struct sockaddr_storage myaddr;
52 struct sockaddr_in *sin;
53 struct sockaddr_in6 *sin6;
54 int proto, portrange, portlow;
55 u_int16_t port;
56 socklen_t salen;
57
58 if (sa == NULL) {
59 salen = sizeof(myaddr);
60 sa = (struct sockaddr *)&myaddr;
61
62 if (getsockname(sd, sa, &salen) == -1)
63 return -1; /* errno is correctly set */
64
65 af = sa->sa_family;
66 memset(&myaddr, 0, salen);
67 } else
68 af = sa->sa_family;
69
70 if (af == AF_INET) {
71 proto = IPPROTO_IP;
72 portrange = IP_PORTRANGE;
73 portlow = IP_PORTRANGE_LOW;
74 sin = (struct sockaddr_in *)sa;
75 salen = sizeof(struct sockaddr_in);
76 port = sin->sin_port;
77 } else if (af == AF_INET6) {
78 proto = IPPROTO_IPV6;
79 portrange = IPV6_PORTRANGE;
80 portlow = IPV6_PORTRANGE_LOW;
81 sin6 = (struct sockaddr_in6 *)sa;
82 salen = sizeof(struct sockaddr_in6);
83 port = sin6->sin6_port;
84 } else {
85 errno = EPFNOSUPPORT;
86 return (-1);
87 }
88 sa->sa_family = af;
89 sa->sa_len = salen;
90
91 if (port == 0) {
92 socklen_t oldlen = sizeof(old);
93
94 error = getsockopt(sd, proto, portrange, &old, &oldlen);
95 if (error == -1)
96 return (error);
97
98 error = setsockopt(sd, proto, portrange, &portlow,
99 sizeof(portlow));
100 if (error == -1)
101 return (error);
102 }
103
104 error = bind(sd, sa, salen);
105
106 if (port == 0) {
107 int saved_errno = errno;
108
109 if (error) {
110 if (setsockopt(sd, proto, portrange, &old,
111 sizeof(old)) == -1)
112 errno = saved_errno;
113 return (error);
114 }
115
116 if (sa != (struct sockaddr *)&myaddr) {
117 /* Hmm, what did the kernel assign... */
118 if (getsockname(sd, sa, &salen) == -1)
119 errno = saved_errno;
120 return (error);
121 }
122 }
123 return (error);
124 }
125 DEF_WEAK(bindresvport_sa);
126