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      1 /* This file has be substantially modified from the original OpenBSD source */
      2 
      3 /*	$OpenBSD: bindresvport.c,v 1.17 2005/12/21 01:40:22 millert 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 /* OPENBSD ORIGINAL: lib/libc/rpc/bindresvport.c */
     32 
     33 #include "includes.h"
     34 
     35 #ifndef HAVE_BINDRESVPORT_SA
     36 #include <sys/types.h>
     37 #include <sys/socket.h>
     38 
     39 #include <netinet/in.h>
     40 #include <arpa/inet.h>
     41 
     42 #include <errno.h>
     43 #include <string.h>
     44 
     45 #define STARTPORT 600
     46 #define ENDPORT (IPPORT_RESERVED - 1)
     47 #define NPORTS	(ENDPORT - STARTPORT + 1)
     48 
     49 /*
     50  * Bind a socket to a privileged IP port
     51  */
     52 int
     53 bindresvport_sa(int sd, struct sockaddr *sa)
     54 {
     55 	int error, af;
     56 	struct sockaddr_storage myaddr;
     57 	struct sockaddr_in *in;
     58 	struct sockaddr_in6 *in6;
     59 	u_int16_t *portp;
     60 	u_int16_t port;
     61 	socklen_t salen;
     62 	int i;
     63 
     64 	if (sa == NULL) {
     65 		memset(&myaddr, 0, sizeof(myaddr));
     66 		sa = (struct sockaddr *)&myaddr;
     67 
     68 		if (getsockname(sd, sa, &salen) == -1)
     69 			return -1;	/* errno is correctly set */
     70 
     71 		af = sa->sa_family;
     72 		memset(&myaddr, 0, salen);
     73 	} else
     74 		af = sa->sa_family;
     75 
     76 	if (af == AF_INET) {
     77 		in = (struct sockaddr_in *)sa;
     78 		salen = sizeof(struct sockaddr_in);
     79 		portp = &in->sin_port;
     80 	} else if (af == AF_INET6) {
     81 		in6 = (struct sockaddr_in6 *)sa;
     82 		salen = sizeof(struct sockaddr_in6);
     83 		portp = &in6->sin6_port;
     84 	} else {
     85 		errno = EPFNOSUPPORT;
     86 		return (-1);
     87 	}
     88 	sa->sa_family = af;
     89 
     90 	port = ntohs(*portp);
     91 	if (port == 0)
     92 		port = arc4random_uniform(NPORTS) + STARTPORT;
     93 
     94 	/* Avoid warning */
     95 	error = -1;
     96 
     97 	for(i = 0; i < NPORTS; i++) {
     98 		*portp = htons(port);
     99 
    100 		error = bind(sd, sa, salen);
    101 
    102 		/* Terminate on success */
    103 		if (error == 0)
    104 			break;
    105 
    106 		/* Terminate on errors, except "address already in use" */
    107 		if ((error < 0) && !((errno == EADDRINUSE) || (errno == EINVAL)))
    108 			break;
    109 
    110 		port++;
    111 		if (port > ENDPORT)
    112 			port = STARTPORT;
    113 	}
    114 
    115 	return (error);
    116 }
    117 
    118 #endif /* HAVE_BINDRESVPORT_SA */
    119