openssh/bsd-bindresvport.c

/*
 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
 * unrestricted use provided that this legend is included on all tape
 * media and as a part of the software program in whole or part.  Users
 * may copy or modify Sun RPC without charge, but are not authorized
 * to license or distribute it to anyone else except as part of a product or
 * program developed by the user.
 * 
 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
 * 
 * Sun RPC is provided with no support and without any obligation on the
 * part of Sun Microsystems, Inc. to assist in its use, correction,
 * modification or enhancement.
 * 
 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
 * OR ANY PART THEREOF.
 * 
 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
 * or profits or other special, indirect and consequential damages, even if
 * Sun has been advised of the possibility of such damages.
 * 
 * Sun Microsystems, Inc.
 * 2550 Garcia Avenue
 * Mountain View, California  94043
 */

#include "config.h"

#ifndef HAVE_BINDRESVPORT_AF

#if defined(LIBC_SCCS) && !defined(lint)
static char *rcsid = "$OpenBSD: bindresvport.c,v 1.11 1999/12/17 19:22:08 deraadt Exp $";
#endif /* LIBC_SCCS and not lint */

/*
 * Copyright (c) 1987 by Sun Microsystems, Inc.
 *
 * Portions Copyright(C) 1996, Jason Downs.  All rights reserved.
 */

#include "includes.h"

#define STARTPORT 600
#define ENDPORT (IPPORT_RESERVED - 1)
#define NPORTS	(ENDPORT - STARTPORT + 1)

/*
 * Bind a socket to a privileged IP port
 */
int
bindresvport_af(sd, sa, af)
	int sd;
	struct sockaddr *sa;
	int af;
{
	int error;
	struct sockaddr_storage myaddr;
	struct sockaddr_in *sin;
	struct sockaddr_in6 *sin6;
	u_int16_t *portp;
	u_int16_t port;
	socklen_t salen;
	int i;

	if (sa == NULL) {
		memset(&myaddr, 0, sizeof(myaddr));
		sa = (struct sockaddr *)&myaddr;
	}

	if (af == AF_INET) {
		sin = (struct sockaddr_in *)sa;
		salen = sizeof(struct sockaddr_in);
		portp = &sin->sin_port;
	} else if (af == AF_INET6) {
		sin6 = (struct sockaddr_in6 *)sa;
		salen = sizeof(struct sockaddr_in6);
		portp = &sin6->sin6_port;
	} else {
		errno = EPFNOSUPPORT;
		return (-1);
	}
	sa->sa_family = af;

	port = ntohs(*portp);
	if (port == 0)
		port = (arc4random() % NPORTS) + STARTPORT;

	for(i = 0; i < NPORTS; i++) {
		*portp = htons(port);
		
		error = bind(sd, sa, salen);
		
		/* Terminate on success */
		if (error == 0)
			break;
			
		/* Terminate on errors, except "address already in use" */
		if ((error < 0) && !((errno == EADDRINUSE) || (errno == EINVAL)))
			break;
			
		port++;
		if (port > ENDPORT)
			port = STARTPORT;
	}

	return (error);
}

#endif /* HAVE_BINDRESVPORT_AF */