raw socket 编程实例 raw socket编程实例

54 阅读 0 评论 36 点赞

我是靠谱客的博主玩命网络，最近开发中收集的这篇文章主要介绍raw socket 编程实例 raw socket编程实例，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

raw socket编程实例

2016年12月01日 00:58:28 1685人阅读评论(0) 收藏举报

分类：

网络编程（5）

由于最经做模拟TCP三次握手的实验，需要用到raw socket编程。

运行第一段代码，发送ip数据报，第二段代码接收ip数据报。需要运行第二段代码，否则将无法接收数据报。

[cpp] view plain copy

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
struct iphead{ //该结构体模拟IP首部（代码中，控制套接字不添加IP数据包首部，需要自己添加），

[cpp] view plain copy

//关于各变量的含义，可对照IP数据报格式，一目了然。
unsigned char ip_hl:4, ip_version:4; //ip_hl,ip_version各占四个bit位。
unsigned char ip_tos;
unsigned short int ip_len;
unsigned short int ip_id;
unsigned short int ip_off;
unsigned char ip_ttl;
unsigned char ip_pro;
unsigned short int ip_sum;
unsigned int ip_src;
unsigned int ip_dst;
};
struct icmphead{ //该结构体模拟ICMP报文首部
unsigned char icmp_type;
unsigned char icmp_code;
unsigned short int icmp_sum;
unsigned short int icmp_id;
unsigned short int icmp_seq;
};
unsigned short int cksum(char buffer[], int size){ //计算校验和，具体的算法可自行百度，或查阅资料
unsigned long sum = 0;
unsigned short int answer;
unsigned short int *temp;
temp = (short int *)buffer;
for( ; temp<buffer+size; temp+=1){
sum += *temp;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;
return answer;
}
int main(){
int sockfd;
struct sockaddr_in conn;
struct iphead *ip;
struct icmphead *icmp;
unsigned char package[sizeof(struct iphead) + sizeof(struct icmphead)]; //package存储IP数据报的首部和数据
memset(package, 0, sizeof(package));
ip = (struct iphead*)package;
icmp = (struct icmphead*)(package+sizeof(struct iphead)); //IP数据报数据字段仅仅包含一个ICMP首部
sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); //创建套接字
if(sockfd < 0){
printf("Create socket failedn");
return -1;
}
conn.sin_family = AF_INET;
conn.sin_addr.s_addr = inet_addr("192.168.230.135");
int one = 1;
if(setsockopt(sockfd, IPPROTO_IP, IP_HDRINCL, &one, sizeof(one)) < 0){ //设置套接字行为，此处设置套接字不添加IP首部
printf("setsockopt failed!n");
return -1;
}
/*设置IP首部各个字段的值*/
ip->ip_version = 4;
ip->ip_hl = 5;
ip->ip_tos = 0;
ip->ip_len = htons(sizeof(struct iphead) + sizeof(struct icmphead)); //关于htons()、htonl()的作用，可自行百度
ip->ip_id = htons(1);
ip->ip_off = htons(0x4000);
ip->ip_ttl = 10;
ip->ip_pro = IPPROTO_ICMP;
ip->ip_src = htonl(inet_addr("192.168.230.135"));
ip->ip_dst = htonl(inet_addr("192.168.230.135"));
printf("ipcksum : %dn", cksum(package, 20));
ip->ip_sum = cksum(package, 20); // 计算校验和，应当在其他字段之后设置（实验中发现检验和会被自动添加上）
/*设置ICMP首部各字段值*/
icmp->icmp_type = 8;
icmp->icmp_code = 0;
icmp->icmp_id = 1;
icmp->icmp_seq = 0;
icmp->icmp_sum = (cksum(package+20, 8));
/*接下来发送IP数据报即可*/
if(sendto(sockfd, package, htons(ip->ip_len), 0,(struct sockaddr *)&conn, sizeof(struct sockaddr)) < 0){
printf("send failedn");
return -1;
}
printf("send successfuln");
return 0;
}

[plain] view plain copy

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<unistd.h>
#include<linux/if_ether.h>
unsigned short int cksum(char buffer[], int size){ //校验函数
unsigned long sum = 0;
unsigned short int answer;
unsigned short int *temp;
temp = (short int *)buffer;
for( ; temp<buffer+size; temp+=1)
sum += *temp;
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;
return answer;
}
int main(){
unsigned char buffer[1024];
// int sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);//不知为啥，无法设置原始套接字在网络层抓IP数据报
int sockfd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP)); //此处，利用原始套接字在数据链路层抓取MAC帧，去掉
if(sockfd < 0){ //14个字节的MAC帧首部即可
printf("create sock failedn");
return -1;
}
int n = recvfrom(sockfd, buffer, 1024, 0, NULL, NULL); //接收MAC帧
printf("receive %d bytesn", n);
for(int i=14; i<n; i++){ //去掉MAC帧首部，直接输出IP数据报每个字节的数据
if((i-14) % 16 == 0)
printf("n");
printf("%d ",buffer[i]);
}
printf("n");
printf("ipcksum: %dn", cksum(buffer+14, 20)); //此处再次校验时，应当输出0
return 0;
}