使用raw socket构造UDP包不成功

heartlesstoanyone 2012-07-14 05:27:05

抓不到包，请大家帮看看，先行谢过了。第一次接触raw socket编程，实在不知怎么搞了。



#include <errno.h>

#include <sys/socket.h>

#include <arpa/inet.h>

#include <netinet/in.h>

#include <netinet/ip.h>

#include <netinet/udp.h>

#include <sys/time.h>

#include <string.h>



#include <iostream>



using namespace std;



const int LISTEN_PORT = 7800;



const int PACK_LEN = 8192;



struct psdhdr

{

    u_int32_t saddr;

    u_int32_t daddr;

    u_int8_t  zero;

    u_int8_t  protocol;

    u_int16_t len;

};





u_int16_t checksum(u_int16_t *buffer, int size);



int main(int argc, char *argv[])

{

    char payload[] = "hello";

	

	struct sockaddr_in sin, din;

	memset(&sin, 0, sizeof(struct sockaddr_in));

	memset(&din, 0, sizeof(struct sockaddr_in));

	sin.sin_family = AF_INET;

	din.sin_family = AF_INET;

	sin.sin_addr.s_addr = inet_addr("19.9.0.95");

	din.sin_addr.s_addr = inet_addr("18.8.6.66");

	sin.sin_port = htons(LISTEN_PORT);

	din.sin_port = htons(LISTEN_PORT);	



    const int listen_fd = socket(PF_INET, SOCK_RAW, IPPROTO_UDP);

    if (listen_fd < 0)

    {

        cout << "system error [ " << errno << ":" << strerror(errno) << "]"<< endl;

        return 1;

    }



    if (bind(listen_fd, (const struct sockaddr *)&sin, sizeof(sin)) < 0)

    {

        close(listen_fd);

        cout << "system error [ " << errno << ":" << strerror(errno) << "]"<< endl;

        return 1;

    }



	int on = 1;

	if (setsockopt(listen_fd, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on)) < 0)

	{

		cout << "system error [ " << errno << ":" << strerror(errno) << "]" << endl;

		return 1;

	}



    char buf[PACK_LEN] = {0};

    struct iphdr *iphdr = (struct iphdr *) buf;

    struct psdhdr psd;

    struct udphdr *pudphdr = (struct udphdr *) (buf+sizeof(struct iphdr));

	

	memcpy(buf+sizeof(struct iphdr)+sizeof(struct udphdr), payload, strlen(payload));

	const int data_len = sizeof(struct iphdr)+sizeof(struct udphdr)+strlen(payload);

	iphdr->ihl = 5;

	iphdr->version = 4;

	iphdr->tos = 0;

	iphdr->tot_len = data_len;

	iphdr->id = htons(random());

	iphdr->frag_off = 0;

	iphdr->ttl = 0xff;

	iphdr->protocol = IPPROTO_UDP;

	iphdr->check = 0;

	iphdr->saddr = sin.sin_addr.s_addr;

	iphdr->daddr = din.sin_addr.s_addr;

	iphdr->check = checksum((u_int16_t *)buf, sizeof(struct iphdr));



	pudphdr->source = sin.sin_port;

	pudphdr->dest = din.sin_port;

	pudphdr->len = htons(sizeof(struct udphdr)+strlen(payload));

	pudphdr->check = 0;



	psd.saddr = iphdr->saddr;

	psd.daddr = iphdr->daddr;

	psd.zero = 0;

	psd.protocol = IPPROTO_UDP;

	psd.len = pudphdr->len;

	

	char tmp[sizeof(struct psdhdr) + ntohs(pudphdr->len)];

	struct psdhdr *ppsdhdr = (struct psdhdr *) tmp;

	ppsdhdr->saddr = iphdr->saddr;

	ppsdhdr->daddr = iphdr->daddr;

	ppsdhdr->zero = 0;

	ppsdhdr->protocol = IPPROTO_UDP;

	ppsdhdr->len = pudphdr->len;

	memcpy(tmp+sizeof(struct psdhdr), buf+sizeof(struct iphdr), ntohs(pudphdr->len));

	pudphdr->check = checksum((u_int16_t *)tmp, sizeof(tmp));

	

	for (int cnt = 1; cnt < 100; ++cnt)

	{

		if (sendto(listen_fd, buf, data_len, 0, (struct sockaddr *)&sin, sizeof(sin)) < 0)

		{

			cout << "system error [ " << errno << ":" << strerror(errno) << "]" << endl;

			cout << cnt << " failed" << endl;

		}

		else

		{

			cout << cnt << " success" << endl; 

		}

		sleep(2);

	}   



    cout << "Hello world!" << endl;

    return 0;

}



u_int16_t checksum(u_int16_t *buffer, int size)

{

	u_int64_t ret = 0;

	

	while (size > 1)

	{

		ret += *buffer++;

		size -= 2;

	}



	if (size == 1)

	{

		ret += *((u_int8_t *)buffer);

	}



	ret = (ret >> 16) + (ret & 0xffff);

	ret += (ret >> 16);



	return (u_int16_t)(~ret);

}