bindresvport.c revision 124208
1/* This file has be substantially modified from the original OpenBSD source */
2
3/*	$OpenBSD: bindresvport.c,v 1.15 2003/05/20 22:42:35 deraadt Exp $	*/
4
5/*
6 * Copyright 1996, Jason Downs.  All rights reserved.
7 * Copyright 1998, Theo de Raadt.  All rights reserved.
8 * Copyright 2000, Damien Miller.  All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include "includes.h"
32
33#ifndef HAVE_BINDRESVPORT_SA
34
35#include "includes.h"
36
37#define STARTPORT 600
38#define ENDPORT (IPPORT_RESERVED - 1)
39#define NPORTS	(ENDPORT - STARTPORT + 1)
40
41/*
42 * Bind a socket to a privileged IP port
43 */
44int
45bindresvport_sa(sd, sa)
46	int sd;
47	struct sockaddr *sa;
48{
49	int error, af;
50	struct sockaddr_storage myaddr;
51	struct sockaddr_in *sin;
52	struct sockaddr_in6 *sin6;
53	u_int16_t *portp;
54	u_int16_t port;
55	socklen_t salen;
56	int i;
57
58	if (sa == NULL) {
59		memset(&myaddr, 0, 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		sin = (struct sockaddr_in *)sa;
72		salen = sizeof(struct sockaddr_in);
73		portp = &sin->sin_port;
74	} else if (af == AF_INET6) {
75		sin6 = (struct sockaddr_in6 *)sa;
76		salen = sizeof(struct sockaddr_in6);
77		portp = &sin6->sin6_port;
78	} else {
79		errno = EPFNOSUPPORT;
80		return (-1);
81	}
82	sa->sa_family = af;
83
84	port = ntohs(*portp);
85	if (port == 0)
86		port = (arc4random() % NPORTS) + STARTPORT;
87
88	/* Avoid warning */
89	error = -1;
90
91	for(i = 0; i < NPORTS; i++) {
92		*portp = htons(port);
93
94		error = bind(sd, sa, salen);
95
96		/* Terminate on success */
97		if (error == 0)
98			break;
99
100		/* Terminate on errors, except "address already in use" */
101		if ((error < 0) && !((errno == EADDRINUSE) || (errno == EINVAL)))
102			break;
103
104		port++;
105		if (port > ENDPORT)
106			port = STARTPORT;
107	}
108
109	return (error);
110}
111
112#endif /* HAVE_BINDRESVPORT_SA */
113