raw_sock.c

来自「Adhoc无线网络路由协议源码」· C语言 代码 · 共 67 行

#include "raw_sock.h"

/*
 * rawsock_init():
 *	prepare the raw socket and return the handle (file descriptor)
 */
int rawsock_init()
{
  char on = 1;
  int s, r;
  int onr = 1;

	/* raw socket */
	if ((s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0) {
		perror("socket(AF_INET, SOCK_RAW, IPPROTO_RAW)");
		return -1;
	}
	r = setsockopt(s, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on));
	if (r < 0) {
		close (s);
		perror("setsockopt(IPPROTO_IP)");
		return -1;
	}

	/* set SO_REUSEADDR so that more than one process can use the socket */
	if(setsockopt(s,SOL_SOCKET, SO_REUSEADDR, &onr, sizeof(onr)) < 0)
	{
		 perror("rawsock_init() : setsockopt");
		 return -1;
	}
	return (s);
}



/*
 * rawsock_out(fd, buf, len, flags):
 *	write the packet from buf into fd, return bytes actually written
 */
int rawsock_out(int s, unsigned char *buf, int len, int flags)
{
  int r;
  struct sockaddr_in sin;

	sin.sin_family = AF_INET;
	memcpy(&sin.sin_addr.s_addr, buf+16, 4);	/* buf+16: dest ip */
	sin.sin_port = 0;

	r = sendto(s, (void *)buf, len, flags,
			(struct sockaddr *)&sin, sizeof(sin));

#ifdef DEBUG
	{ int i;
		fprintf(stderr, "OUT: (%d) [ ", len);
		for (i = 0; i < 20; i++)
			fprintf(stderr, "%02x ", buf[i]);
		fprintf(stderr, "] = %d\n", r);
	}
#endif

	if (r < 0)
		perror("rawsock_out: sendto()");
	
	return r;
}