sockets.c

一个基于linux的TCP/IP协议栈的实现

/* sockets.h
 * [e-mail]
 * 2006-10-20
 */

#include <sys/socket.h>
#include <stdio.h>
#include <unistd.h>

#include "config.h"
#include "sockets.h"
#include "util.h"
#include "net-support.h"
#include "dummy_ipv4.h"
#include "log.h"

int skfd = -1;			/* generic raw socket desc.     */

int sockets_open( int family )
{
	struct aftype **aft;
	int sfd = -1;
	static int force = -1;

	if( force < 0 ){
		force = 0;
		if( kernel_version() < KRELEASE(2, 1, 0)  )
			force = 1;
		if( access("/proc/net", R_OK) )
			force = 1;
	}

	for( aft = aftypes; *aft; aft++ ){
		struct aftype *af = *aft;
		int type = SOCK_DUMMY;
		if( af->af == AF_UNSPEC )
			continue;
		if( family && family != af->af )
			continue;
		if( af->fd != -1 ){
			sfd = af->fd;
			continue;
		}
		if( !family && !force && af->flag_file ){
			if (access(af->flag_file, R_OK))
				continue;
		}
		af->fd = socket(af->af, type, IPPROTO_DUMMY );
		if (af->fd >= 0)
			sfd = af->fd;
	}
	if( sfd < 0 )
		PR_ERR( "No usable address families found.\n" );
	return sfd;
}