raw socket編程實例

2016年12月01日 00:58:28 1685人閱讀 評論(0) 收藏 舉報 分類： 網絡編程（5）

版權聲明：本文為博主原創文章，未經博主允許不得轉載。 https://blog.csdn.net/nice_wen/article/details/53416063

由于最經做模擬TCP三次握手的實驗，需要用到raw socket編程。

運行第一段代碼，發送ip數據報，第二段代碼接收ip數據報。需要運行第二段代碼，否則將無法接收數據報。

[cpp] view plaincopy

<span?style="font-size:18px;">#include<stdio.h>??

#include<string.h>??

#include<stdlib.h>??

#include<sys/socket.h>??

#include<sys/types.h>??

#include<netinet/in.h>??

??

struct?iphead{???//該結構體模擬IP首部（代碼中，控制套接字不添加IP數據包首部，需要自己添加），</span>??

[cpp] view plaincopy

<span?style="font-size:18px;"><span?style="white-space:pre;">???????</span>//關于各變量的含義，可對照IP數據報格式，一目了然。??

????unsigned?char?ip_hl:4,?ip_version:4;??//ip_hl,ip_version各占四個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{??//</span><span?style="font-size:18px;font-family:Arial,?Helvetica,?sans-serif;">該結構體模擬ICMP報文首部</span><span?style="font-size:18px;">??

????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){???//計算校驗和，具體的算法可自行百度，或查閱資料??

????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存儲IP數據報的首部和數據??

????memset(package,?0,?sizeof(package));??

??

????ip?=?(struct?iphead*)package;??

????icmp?=?(struct?icmphead*)(package+sizeof(struct?iphead));?//IP數據報數據字段僅僅包含一個ICMP首部??

????sockfd?=?socket(AF_INET,?SOCK_RAW,?IPPROTO_ICMP);?//創建套接字??

????if(sockfd?<?0){??

????????printf("Create?socket?failed\n");??

????????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){??//設置套接字行為，此處設置套接字不添加IP首部??

????????printf("setsockopt?failed!\n");??

????????return?-1;??

????}??

????/*設置IP首部各個字段的值*/????

????ip->ip_version?=?4;???

????ip->ip_hl?=?5;??

????ip->ip_tos?=?0;??

????ip->ip_len?=?htons(sizeof(struct?iphead)?+?sizeof(struct?icmphead));?//關于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?:?%d\n",?cksum(package,?20));???

????ip->ip_sum?=?cksum(package,?20);??//?計算校驗和，應當在其他字段之后設置（實驗中發現檢驗和會被自動添加上）??

??????

????/*設置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));??

????/*接下來發送IP數據報即可*/??

????if(sendto(sockfd,?package,?htons(ip->ip_len),?0,(struct?sockaddr?*)&conn,?sizeof(struct?sockaddr))?<?0){??

????printf("send?failed\n");???

????return?-1;??

????}??

????printf("send?successful\n");??????

????return?0;??

}</span>??

[plain] view plaincopy

<span?style="font-size:18px;">#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){??//校驗函數??

????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);//不知為啥，無法設置原始套接字在網絡層抓IP數據報??

????int?sockfd?=?socket(PF_PACKET,?SOCK_RAW,?htons(ETH_P_IP));?//此處，利用原始套接字在數據鏈路層抓取MAC幀，去掉??

????if(sockfd?<?0){????????????????????????????????????????????//14個字節的MAC幀首部即可??

????????printf("create?sock?failed\n");??

????return?-1;??

????}??????

????int?n?=?recvfrom(sockfd,?buffer,?1024,?0,?NULL,?NULL);?//接收MAC幀??

??

????printf("receive?%d?bytes\n",?n);??

????for(int?i=14;?i<n;?i++){??????//去掉MAC幀首部，直接輸出IP數據報每個字節的數據??

????if((i-14)?%?16?==?0)??

????????printf("\n");??

????printf("%d?",buffer[i]);??

????}??

????printf("\n");??

????printf("ipcksum:?%d\n",?cksum(buffer+14,?20));?//此處再次校驗時，應當輸出0??

????return?0;??

}</span>??

這是之前參考過的一篇文章，寫的還可以:http://www.it165.net/pro/html/201208/3450.html

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