udp_socket.c

一个基于linux的TCP/IP协议栈的实现

#include <sys/socket.h>
#include <linux/types.h>
#include <linux/errqueue.h>
#include <sys/ioctl.h>
#include "my_inet.h"
#include <stdio.h>
#include <errno.h>
#include <string.h>

#include <arpa/inet.h>
#include <unistd.h>

int ip_control_msg( struct cmsghdr *msg )
{
	int ret = 0;
	switch( msg->cmsg_type ){
	case IP_RECVERR:
		{	
			struct sock_extended_err *exterr;
			exterr = (struct sock_extended_err *)(CMSG_DATA(msg));
			printf("ee_errno: %u\n", exterr->ee_errno );
			printf("ee_origin: %u\n", exterr->ee_origin );
			printf("ee_type: %u\n", exterr->ee_type );
			printf("ee_code: %u\n", exterr->ee_code );
			printf("ee_pad: %u\n", exterr->ee_pad );
			printf("ee_info: %u\n", exterr->ee_info );
			printf("ee_data: %u\n", exterr->ee_data );
		}
		ret = -1;
		break;
	default:
		break;
	}
	return ret;		
}

int control_msg( struct msghdr *msg )
{
	int ret = 0;
    struct cmsghdr *control_msg = CMSG_FIRSTHDR( msg );
    while( control_msg != NULL ){
        switch( control_msg->cmsg_level ){
        case SOL_IP:
            ret = ip_control_msg( control_msg );
            break;
        default:
            break;
        }
        control_msg = CMSG_NXTHDR( msg, control_msg );
    }
	return ret;
}

int main()
{
	int i;
	struct sockaddr_in dest;
	dest.sin_family = MY_PF_INET;
	dest.sin_port = htons(16000);
	dest.sin_addr.s_addr = 0x013010AC;

	int fd = socket( MY_PF_INET, SOCK_DGRAM, MY_IPPROTO_UDP );
	if( fd < 0 ){
		perror("socket: ");
		return -1;
	}
	if( connect( fd, (struct sockaddr*)&dest, sizeof(dest) ) < 0 ){
		perror("connect: ");
		return -1;
	}

	int val = 1;
	if(	setsockopt( fd, SOL_IP, IP_RECVERR, &val, sizeof(val) ) == -1 ){
		perror("setsockopt: ");
		return -1;
	}
	
	int bwrite = send( fd, "abcdefg", 7, 0 );
	if( bwrite == -1 ){
		perror("send: ");
		return -1;
	}	

	char buf[1024];
	char control_buf[1024];
	struct msghdr msg;
	struct iovec iov = { buf, 1024 };
	memset( &msg, 0, sizeof(msg) );
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_control = &control_buf;
	msg.msg_controllen = 1024;

	int bread = recvmsg( fd, &msg, MSG_ERRQUEUE );
	if( bread == -1 ){
		perror("recv: ");
		return -1;
	}
	if( control_msg( &msg ) >= 0 )
		printf("successed!\n");
	else
		printf("failed!\n");

	close( fd );
	return 0;
}