bindresvport.c

linux下用PCMCIA无线网卡虚拟无线AP的程序源码

/*
 * 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
 */

/*
 * Copyright (c) 1987 by Sun Microsystems, Inc.
 */

#define __FORCE_GLIBC__
#include <features.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/socket.h>
#include <netinet/in.h>

/*
 * Bind a socket to a privileged IP port
 */
int bindresvport(sd, sin)
int sd;
struct sockaddr_in *sin;
{
	int res;
	static short port;
	struct sockaddr_in myaddr;
	extern int errno;
	int i;

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

	if (sin == (struct sockaddr_in *) 0) {
		sin = &myaddr;
		bzero(sin, sizeof(*sin));
		sin->sin_family = AF_INET;
	} else if (sin->sin_family != AF_INET) {
		__set_errno(EPFNOSUPPORT);
		return (-1);
	}
	if (port == 0) {
		port = (getpid() % NPORTS) + STARTPORT;
	}
	res = -1;
	__set_errno(EADDRINUSE);
	for (i = 0; i < NPORTS && res < 0 && errno == EADDRINUSE; i++) {
		sin->sin_port = htons(port++);
		if (port > ENDPORT) {
			port = STARTPORT;
		}
		res = bind(sd, (struct sockaddr *)sin, (socklen_t)sizeof(struct sockaddr_in));
	}
	return (res);
}