1 /* $OpenBSD: bindresvport.c,v 1.17 2005/12/21 01:40:22 millert 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 38 bindresvport(int sd, struct sockaddr_in *sin) 39 { 40 return bindresvport_sa(sd, (struct sockaddr *)sin); 41 } 42 43 /* 44 * Bind a socket to a privileged port for whatever protocol. 45 */ 46 int 47 bindresvport_sa(int sd, struct sockaddr *sa) 48 { 49 int old, error, af; 50 struct sockaddr_storage myaddr; 51 struct sockaddr_in *sin; 52 struct sockaddr_in6 *sin6; 53 int proto, portrange, portlow; 54 u_int16_t port; 55 socklen_t salen; 56 57 if (sa == NULL) { 58 salen = sizeof(myaddr); 59 sa = (struct sockaddr *)&myaddr; 60 61 if (getsockname(sd, sa, &salen) == -1) 62 return -1; /* errno is correctly set */ 63 64 af = sa->sa_family; 65 memset(&myaddr, 0, salen); 66 } else 67 af = sa->sa_family; 68 69 if (af == AF_INET) { 70 proto = IPPROTO_IP; 71 portrange = IP_PORTRANGE; 72 portlow = IP_PORTRANGE_LOW; 73 sin = (struct sockaddr_in *)sa; 74 salen = sizeof(struct sockaddr_in); 75 port = sin->sin_port; 76 } else if (af == AF_INET6) { 77 proto = IPPROTO_IPV6; 78 portrange = IPV6_PORTRANGE; 79 portlow = IPV6_PORTRANGE_LOW; 80 sin6 = (struct sockaddr_in6 *)sa; 81 salen = sizeof(struct sockaddr_in6); 82 port = sin6->sin6_port; 83 } else { 84 errno = EPFNOSUPPORT; 85 return (-1); 86 } 87 sa->sa_family = af; 88 sa->sa_len = salen; 89 90 if (port == 0) { 91 socklen_t oldlen = sizeof(old); 92 93 error = getsockopt(sd, proto, portrange, &old, &oldlen); 94 if (error < 0) 95 return (error); 96 97 error = setsockopt(sd, proto, portrange, &portlow, 98 sizeof(portlow)); 99 if (error < 0) 100 return (error); 101 } 102 103 error = bind(sd, sa, salen); 104 105 if (port == 0) { 106 int saved_errno = errno; 107 108 if (error) { 109 if (setsockopt(sd, proto, portrange, &old, 110 sizeof(old)) < 0) 111 errno = saved_errno; 112 return (error); 113 } 114 115 if (sa != (struct sockaddr *)&myaddr) { 116 /* Hmm, what did the kernel assign... */ 117 if (getsockname(sd, sa, &salen) < 0) 118 errno = saved_errno; 119 return (error); 120 } 121 } 122 return (error); 123 } 124