006.udp转发包并代理访问服务器总结

背景：

当加速器(client)拦截了游戏客户端发送的完整数据包(package)时，将package传给中间服务器(mid_server)，经过自己的链路传输数据之后，中间服务器模拟游戏客户端将数据发给游戏服务器(end_server)，目的服务器收到请求后回应，回应的包以同样的方式返回，直到游戏客户端收到数据包。

原理及实现：

1.我们需要三个主机来模拟这个请求：

client_server: IP:192.168.11.104

mid_server: IP:192.168.11.105

end_server: IP:192.168.11.106

程序的流程图：

其中：

1.client_server只是充当普通的udp客户端，不同的是我们发送的数据是一个完整的udp类型的IP数据包

2.end_server模拟的是一台普通的游戏服务器，当有客户请求的时候，它就会回应

3.mid_server代替游戏客户端的请求，将数据包中替换了请求IP和port后发给游戏服务器，获得服务。

当游戏服务器回应数据后，同样再次将数据封装成一个完整的udp的IP数据包，填入相应的服务器IP，服务器端口，客户端IP，客户端端口，将这个数据包作为数据发给client_server

4.client_server将完整的数据包发给游戏服务器。

代码实现：

1.client_server部分：

 /*

  ============================================================================

  Name        : udp_client.c

  Author      : huh

  Version     :

  Copyright   : ---notice---

  Description : Hello World in C, Ansi-style

  ============================================================================

  */

 #include <sys/types.h>

 #include <sys/socket.h>

 #include <stdio.h>

 #include <netinet/in.h>

 #include <arpa/inet.h>

 #include <unistd.h>

 #include <stdlib.h>

 #include <string.h>

 #include <netinet/ip_icmp.h>

 #include <netinet/udp.h>

 #define MAXLINE 1024*10

 int make_message(char *mesg, char sendbuf[], int send_buf_len, uint32_t src_ip, u_int16_t src_port, uint32_t des_ip, u_int16_t des_port);

 int main()

 {

     int server_sockfd;

     char send_message[MAXLINE];

     char recv_message[MAXLINE];

     struct sockaddr_in server_address;

     server_sockfd = socket(AF_INET, SOCK_DGRAM, );

     bzero(&server_address,sizeof(server_address));

     server_address.sin_family = AF_INET;

     server_address.sin_addr.s_addr = inet_addr("192.168.11.105");

     server_address.sin_port = htons();

     int mesg_len;

     bzero(&send_message, MAXLINE);

     mesg_len = make_message("hello world!", send_message, MAXLINE, inet_addr("192.168.11.104"), , inet_addr("192.168.11.106"), );

     //printf("send message len:%d\n",strlen(send_message));

     sendto(server_sockfd, send_message, mesg_len, , (struct sockaddr *)&server_address, sizeof(server_address));  //将包发出去

     bzero(&recv_message, sizeof(recv_message));

     int len = recvfrom(server_sockfd, recv_message, MAXLINE, , NULL, NULL);

     printf("当前收到的IP数据包的内容：\n");

     struct iphdr *ip;

     ip = (struct iphdr *)recv_message;

     struct udphdr *udp;

     udp = (struct udphdr *)(recv_message + sizeof(struct iphdr));

     struct in_addr ad;

     ad.s_addr = ip->saddr;

     printf("src_ip:%s\n",inet_ntoa(ad));

     printf("src_port:%d\n",ntohs(udp->source));

     ad.s_addr = ip->daddr;

     printf("des_ip:%s\n",inet_ntoa(ad));

     printf("des_port:%d\n",ntohs(udp->dest));

     printf("data:%s\ndata len:%d\n",(recv_message+),len);

         close(server_sockfd);

     return ;

 }

udp_client.c

 /*

  * make_message.c

  *

  *  Created on: 2015年11月18日

  *      Author: root

  */

 #include <sys/types.h>

 #include <sys/socket.h>

 #include <stdio.h>

 #include <netinet/in.h>

 #include <arpa/inet.h>

 #include <unistd.h>

 #include <stdlib.h>

 #include <string.h>

 #include <netinet/ip_icmp.h>

 #include <netinet/udp.h>

 #define MAXLINE 1024*10

 struct udp_front  //udp

 {

     uint32_t srcip;

     uint32_t desip;

     u_int8_t zero;

     u_int8_t protocol;

     u_int16_t len;

 };

 u_int16_t in_chksum(u_int16_t *addr, int len);

 u_int16_t udp_check(char *sendbuf, int len, const struct udp_front front);

 int make_message(char *mesg, char sendbuf[], int send_buf_len, uint32_t src_ip, u_int16_t src_port, uint32_t des_ip, u_int16_t des_port);

 //拼接IP数据报

 int make_message(char *mesg, char sendbuf[], int send_buf_len, uint32_t src_ip, u_int16_t src_port, uint32_t des_ip, u_int16_t des_port)

 {

     char message[MAXLINE];

     bzero(message, sizeof(message));

     strcpy(message,mesg);

     printf("message len:%d\n",strlen(message));

     struct iphdr *ip;

     ip = (struct iphdr *)sendbuf;

     ip->ihl = sizeof(struct iphdr) >> ; //首部长度

     ip->version = ;   //ip协议版本

     ip->tos = ;   //服务类型字段

     ip->tot_len = ;   //总长度

     ip->id = ;   //

     ip->frag_off = ;

     ip->ttl = ;

     ip->protocol = IPPROTO_UDP;

     ip->check = ;  //内核会算相应的效验和

     ip->saddr = src_ip;

     ip->daddr = des_ip;

     struct udp_front front;

     front.srcip = src_ip;

     front.desip = des_ip;

     front.len = htons(+strlen(message));

     front.protocol = ;

     front.zero = ;

     struct udphdr *udp;

     udp = (struct udphdr *)(sendbuf + sizeof(struct iphdr));

     udp->source = htons(src_port);  //源端口

     udp->dest = htons(des_port);    //目的端口

     udp->check = ;   //效验和，效验整个udp数据报

     strcpy((sendbuf++), message);

     udp->len = htons(+strlen(message)); //udp数据报总长度

     udp->check = udp_check((sendbuf+), +strlen(message), front);

     ip->tot_len = ( +  + strlen(message));   //总长度

     printf("ip->tot_len:%d\n",ip->tot_len);

     ip->check = in_chksum((unsigned short *)sendbuf, );

     return (ip->tot_len);

 }

 //计算udp效验和

 unsigned short udp_check(char *sendbuf, int len, const struct udp_front front)

 {

     char str[MAXLINE];

     bzero(&str, MAXLINE);

     bcopy(&front, str, sizeof(front));

     bcopy(sendbuf, str+sizeof(front), len);

     struct udp_front *ptr;

     ptr = (struct udp_front *)str;

     char *s;

     s = (str+);

     return in_chksum((unsigned short *)str, sizeof(front)+len);

 }

 //效验和算法

 uint16_t in_chksum(uint16_t *addr, int len)

 {

     int nleft = len;

     uint32_t sum = ;

     uint16_t *w = addr;

     uint16_t answer = ;

     //把ICMP报头二进制数据以2字节为单位累加起来

     while (nleft > )

     {

         sum += *w++;

         nleft -= ;

     }

     if (nleft == )

     {

         *(unsigned char *)(&answer) = *(unsigned char *)w;

         sum += answer;

     }

     sum = (sum>>) + (sum&0xffff);

     sum += (sum>>);

     answer = ~sum;

     return answer;

 }

make_message.c

2.mid_server部分：

 /*

  ============================================================================

  Name        : udp_mid_server.c

  Author      : huh

  Version     :

  Copyright   : ---notice---

  Description : Hello World in C, Ansi-style

  ============================================================================

  */

 #include <sys/types.h>

 #include <sys/socket.h>

 #include <stdio.h>

 #include <netinet/in.h>

 #include <arpa/inet.h>

 #include <unistd.h>

 #include <stdlib.h>

 #include <string.h>

 #include <netinet/ip_icmp.h>

 #include <netinet/udp.h>

 #define MAXLINE 1024*50

 #define SERVER_IP       "192.168.11.105"   //本服务器IP

 #define TO_CLI_PORT 8600               //本服务器监听client_server端口

 #define TO_END_PORT 8601               //本服务器监听end_server端口

 #define END_SERVER_IP "192.168.11.106" //end_server的ip

 #define END_SERVER_PORT 8686           //end_server的port

 struct udp_front  //udp

 {

     uint32_t srcip;

     uint32_t desip;

     u_int8_t zero;

     u_int8_t protocol;

     u_int16_t len;

 };

 uint32_t client_ip;

 int client_port;

 extern u_int16_t in_chksum(u_int16_t *addr, int len);

 extern u_int16_t udp_check(char *sendbuf, int len, const struct udp_front front);

 extern int make_message(char *mesg, char sendbuf[], int send_buf_len, uint32_t src_ip, u_int16_t src_port, uint32_t des_ip, u_int16_t des_port);

 void change_src(char sendbuf[], int len, uint32_t src_ip, int src_port)

 {

     struct iphdr *ip;

     ip = (struct iphdr *)sendbuf;

     ip->check = ;  //内核会算相应的效验和

     client_ip = ip->saddr;

     ip->saddr = src_ip;

     ip->check = in_chksum((unsigned short *)sendbuf, );

     ;

     struct udp_front front;

     front.srcip = src_ip;

     front.desip = ip->daddr;

     front.len = htons(len-);

     front.protocol = ;

     front.zero = ;

     struct udphdr *udp;

     udp = (struct udphdr *)(sendbuf + sizeof(struct iphdr));

     client_port = ntohs(udp->source);

     udp->source = htons(src_port);  //源端口

     udp->check = ;   //效验和，效验整个udp数据报

     udp->check = udp_check((sendbuf+), len-, front);

 }

 void send_1(int raw_sockfd, char *send_message, int len)

 {

         struct sockaddr_in server_addr;

         bzero(&server_addr,sizeof(server_addr));

         server_addr.sin_family = AF_INET;

         server_addr.sin_addr.s_addr = inet_addr(END_SERVER_IP);

         change_src(send_message, len, inet_addr(SERVER_IP), TO_END_PORT);

         sendto(raw_sockfd, send_message, len, , (struct sockaddr *) &server_addr, sizeof(server_addr));  //将包发出去

         printf("前往end_server的包已经出发！\n");

 }

 int main()

 {

         int size = *;

     int server_len, client_len;

     struct sockaddr_in server_address;

     struct sockaddr_in client_address;

     //接收client_server端数据的套接字

     //监听端口：8600

     int server_sockfd;

     server_sockfd = socket(AF_INET, SOCK_DGRAM, );

     bzero(&server_address,sizeof(server_address));

     server_address.sin_family = AF_INET;

     server_address.sin_addr.s_addr = inet_addr(SERVER_IP);

     server_address.sin_port = htons(TO_CLI_PORT);

     server_len = sizeof(server_address);

     bind(server_sockfd, (struct sockaddr *)&server_address, server_len);

     //发送给end_server的原始套接字

     int raw_sockfd;

     raw_sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);

     setsockopt(raw_sockfd, IPPROTO_IP, IP_HDRINCL, &size, sizeof(size));

     //接收end_server端数据的套接字

     //监听端口：8601

     int end_sockfd;

     end_sockfd = socket(AF_INET, SOCK_DGRAM, );

     bzero(&server_address,sizeof(server_address));

     server_address.sin_family = AF_INET;

     server_address.sin_addr.s_addr = inet_addr(SERVER_IP);

     server_address.sin_port = htons(TO_END_PORT);

     server_len = sizeof(server_address);

     bind(end_sockfd, (struct sockaddr *)&server_address, server_len);

     char recv_mesg[MAXLINE];

     char send_mesg[MAXLINE];

     for( ; ; )

     {

                 int len;

                 client_len = sizeof(struct sockaddr_in);

                 printf("server waiting!\n");

                 //接收来自client_server的包

                 bzero(&client_address, sizeof(client_address));

                 len = recvfrom(server_sockfd, recv_mesg, MAXLINE, , (struct sockaddr *) &client_address, (socklen_t *) &client_len);

                 printf("来自client_server的IP数据包的长度为:%d\n",len);

                 //将接收到的数据作为一个完整的IP包发给end_server

                 send_1(raw_sockfd, recv_mesg, len);

                 //接收来自end_server的回应包，并将数据存在recv_mesg里面

                 bzero(recv_mesg, sizeof(recv_mesg));

                 len = recvfrom(end_sockfd, recv_mesg, MAXLINE, , NULL, NULL);

                 printf("收到来自end_server的应答：%s,长度：%d\n",recv_mesg,len);

                 //现在将end_server给我的包拼接好后发给client_server.

                 printf("client:%d\n",client_port);

                 bzero(send_mesg,sizeof(send_mesg));

                 int mesg_len = make_message(recv_mesg, send_mesg, MAXLINE, inet_addr(END_SERVER_IP), END_SERVER_PORT, client_ip, client_port);

                 sendto(server_sockfd, send_mesg, mesg_len, , (struct sockaddr *) &client_address, client_len);

     }

     return ;

 }

udp_mid_server.c

 /*

  * make_message.c

  *

  *  Created on: 2015年11月18日

  *      Author: root

  */

 #include <sys/types.h>

 #include <sys/socket.h>

 #include <stdio.h>

 #include <netinet/in.h>

 #include <arpa/inet.h>

 #include <unistd.h>

 #include <stdlib.h>

 #include <string.h>

 #include <netinet/ip_icmp.h>

 #include <netinet/udp.h>

 #define MAXLINE 1024*10

 struct udp_front  //udp

 {

     uint32_t srcip;

     uint32_t desip;

     u_int8_t zero;

     u_int8_t protocol;

     u_int16_t len;

 };

 u_int16_t in_chksum(u_int16_t *addr, int len);

 u_int16_t udp_check(char *sendbuf, int len, const struct udp_front front);

 //拼接IP数据报

 int make_message(char *mesg, char sendbuf[], int send_buf_len, uint32_t src_ip, u_int16_t src_port, uint32_t des_ip, u_int16_t des_port)

 {

     char message[MAXLINE];

     bzero(message, sizeof(message));

     strcpy(message,mesg);

     printf("message len:%d\n",strlen(message));

     struct iphdr *ip;

     ip = (struct iphdr *)sendbuf;

     ip->ihl = sizeof(struct iphdr) >> ; //首部长度

     ip->version = ;   //ip协议版本

     ip->tos = ;   //服务类型字段

     ip->tot_len = ;   //总长度

     ip->id = ;   //

     ip->frag_off = ;

     ip->ttl = ;

     ip->protocol = IPPROTO_UDP;

     ip->check = ;  //内核会算相应的效验和

     ip->saddr = src_ip;

     ip->daddr = des_ip;

     struct udp_front front;

     front.srcip = src_ip;

     front.desip = des_ip;

     front.len = htons(+strlen(message));

     front.protocol = ;

     front.zero = ;

     struct udphdr *udp;

     udp = (struct udphdr *)(sendbuf + sizeof(struct iphdr));

     udp->source = htons(src_port);  //源端口

     udp->dest = htons(des_port);    //目的端口

     udp->check = ;   //效验和，效验整个udp数据报

     strcpy((sendbuf++), message);

     udp->len = htons(+strlen(message)); //udp数据报总长度

     udp->check = udp_check((sendbuf+), +strlen(message), front);

     ip->tot_len = ( +  + strlen(message));   //总长度

     printf("ip->tot_len:%d\n",ip->tot_len);

     ip->check = in_chksum((unsigned short *)sendbuf, );

     return (ip->tot_len);

 }

 //计算udp效验和

 unsigned short udp_check(char *sendbuf, int len, const struct udp_front front)

 {

     char str[MAXLINE];

     bzero(&str, MAXLINE);

     bcopy(&front, str, sizeof(front));

     bcopy(sendbuf, str+sizeof(front), len);

     struct udp_front *ptr;

     ptr = (struct udp_front *)str;

     char *s;

     s = (str+);

     return in_chksum((unsigned short *)str, sizeof(front)+len);

 }

 //效验和算法

 uint16_t in_chksum(uint16_t *addr, int len)

 {

     int nleft = len;

     uint32_t sum = ;

     uint16_t *w = addr;

     uint16_t answer = ;

     //把ICMP报头二进制数据以2字节为单位累加起来

     while (nleft > )

     {

         sum += *w++;

         nleft -= ;

     }

     if (nleft == )

     {

         *(unsigned char *)(&answer) = *(unsigned char *)w;

         sum += answer;

     }

     sum = (sum>>) + (sum&0xffff);

     sum += (sum>>);

     answer = ~sum;

     return answer;

 }

make_message.c

3.end_srever部分：

 /*

  ============================================================================

  Name        : udp_end_server.c

  Author      : huh

  Version     :

  Copyright   : ---notice---

  Description : Hello World in C, Ansi-style

  ============================================================================

  */

 #include <sys/types.h>

 #include <sys/socket.h>

 #include <stdio.h>

 #include <netinet/in.h>

 #include <arpa/inet.h>

 #include <unistd.h>

 #include <stdlib.h>

 #include <string.h>

 #define MAXLINE 1024*50

 #define SERVER_IP       "192.168.11.106"   //本服务器IP

 #define SERVER_PORT 8686               //本服务器监听端口

 int main()

 {

     int server_sockfd;

     char recv_mesg[MAXLINE];

     int server_len, client_len;

     struct sockaddr_in server_address;

     struct sockaddr_in client_address;

     server_sockfd = socket(AF_INET, SOCK_DGRAM, );

     server_address.sin_family = AF_INET;

     server_address.sin_addr.s_addr = inet_addr(SERVER_IP);

     server_address.sin_port = htons(SERVER_PORT);

     server_len = sizeof(server_address);

     bind(server_sockfd, (struct sockaddr *)&server_address, server_len);

     //我们会将收到的数据加上"by end server!",再返回给客户端

     while()

     {

         int len;

         client_len = sizeof(struct sockaddr_in);

         printf("end server waiting!\n");

         bzero(recv_mesg, sizeof(recv_mesg));

         len = recvfrom(server_sockfd, recv_mesg, MAXLINE, , (struct sockaddr *) &client_address, (socklen_t *) &client_len);

         printf("收到mid_server包的长度为:%d,内容为:%s\n", len, recv_mesg);

         strcpy(recv_mesg+len," by end_server!");

         len = strlen(recv_mesg);

         sendto(server_sockfd, recv_mesg, len, , (struct sockaddr *) &client_address, client_len);  //将包发出去

         printf("往mid_server回应的包已经出发!\n");

     }

     return ;

 }

udp_end_server.c

监听中间服务器显示的结果：

 [root@mid_server ~]# tcpdump -nn udp and host 192.168.11.105

 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

 listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes

 22:25:24.085794 IP 192.168.11.104.45375 > 192.168.11.105.8600: UDP, length 40

 22:25:24.086092 IP 192.168.11.105.8601 > 192.168.11.106.8686: UDP, length 12

 22:25:24.086632 IP 192.168.11.106.8686 > 192.168.11.105.8601: UDP, length 27

 22:25:24.086891 IP 192.168.11.105.8600 > 192.168.11.104.45375: UDP, length 55

006.udp转发包并代理访问服务器总结的更多相关文章

Py之Crawler：爬虫利用随机选取代理访问服务器的方法实现下载某网址上所有的图片到指定文件夹——Jason niu
#Py之Crawler:爬虫利用随机选取代理访问服务器的方法实现下载某网址上所有的图片到指定文件夹 import urllib.request import os import random def ...
python使用代理访问服务器
python使用代理访问服务器主要有一下3个步骤: 1.创建一个代理处理器ProxyHandler: proxy_support = urllib.request.ProxyHandler(),Pro ...
UDP协议发包的使用（DatagramSocket、DatagramPacket）
1.UDP 是User Datagram Protocol的简称, 中文名是用户数据报协议,是OSI(Open System Interconnection,开放式系统互联) 参考模型中一种无连接的传 ...
【http代理报文】通过发包实现代理请求网页内容
工作中,我们难免需要通过TCP/IP协议发送报文来直接请求网页内容(比如爬虫工具),有同学问如何通过HTTP代理来请求网页,其实我们只需要把报文稍稍修改下,发送给代理服务器即可实现. 基础不过关的朋友 ...
udp之关于linux udp收发包缓冲区大小
1.修订单个socket的缓冲区大小:通过setsockopt使用SO_RCVBUF来设置接收缓冲区,该参数在设置的时候不会与rmem_max进行对比校验,但是如果设置的大小超过rmem_max的话, ...
记录一个UDP收包丢包的问题
这几天写GB28181平台接入层代码,对收到的PS包进行解包时,总是出现误码,最终导致rtsp点播服务中画面花屏. 分析了码流抓包数据之后,发现网络上没有丢包,遂认为PS流解包代码有bug,于是埋头分 ...
ss与udp转发的释疑
转载: http://shadowsocks.info/shadowsocks-udp/ VPS购买地址 udp是什么:UDP 是User Datagram Protocol的简称, 中文名是用户数据 ...
python--socket/Socketerver并发/udp
Socketerve并发基于tcp套接字,关键就是两个循环,一个链接循环,一个通讯循环 Socketserver模块中分两个大类:server类(解决链接问题)和request类(解决通信问题) s ...
网络游戏程序员须知 UDP vs TCP（转）
本文为作者原创或翻译,转载请注明,不得用于商业用途. 作者:rellikt@gmail.com 首发链接:http://blog.csdn.net/rellikt/archive/2010/08/21 ...

随机推荐

Python遍历文件夹
许多次需要用python来遍历目录下文件, 这一次就整理了记录在这里. 随实际工作,不定期更新. import os class FileTraversal: def __init__(self, r ...
MAC使用CocoaPods
前言,還是那句話,按照濤叔下面畫黃色的步驟順序執行就好了使用CocoaPods兩種方式:使用之前安裝的插件&命令行. 一.利用插件 1.創建項目后添加CocoaPods 2.在文本框中輸入如 ...
Guava学习笔记：Guava新增集合类型-Multimap
在日常的开发工作中,我们有的时候需要构造像Map<K, List<V>>或者Map<K, Set<V>>这样比较复杂的集合类型的数据结构,以便做相应的业 ...
接口测试之webservice
什么是Webservice Web service是一个平台独立的,低耦合的,自包含的.基于可编程的web的应用程序,可使用开放的XML(标准通用标记语言下的一个子集)标准来描述.发布.发现.协调和配 ...
深入理解：JavaScript原型与继承
深入理解:JavaScript原型与继承看过不少书籍,不少文章,对于原型与继承的说明基本上让人不明觉厉,特别是对于习惯了面向对象编程的人来说更难理解,这里我就给大家说说我的理解. 首先JavaScr ...
WinForm-GridView
前端: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="CKXM.aspx. ...
SharePoint基于windows验证的如何通过组策略实现IE自动以当前域账号登录SP站点
通过组策略实现IE自动以当前域账号登录SP站点 1. 在运行中运行MMC,启动"组策略对象编辑器". 如下图: 找到组策略如下图: 找到域点右键编辑找到如下图: 找到[计算机配 ...
Basic Virus's Infection & Variation [Python]
Learn from here Initial #!/usr/bin/python2.7 #MAGIC_STRING_skd83749872 import os import __main__ imp ...
No architectures to compile for (ONLY_ACTIVE_ARCH=YES, active arch=x86_64, VALID_ARCHS=i386)
今天在运行一个老ios项目的时候,突然报错:No architectures to compile for (ONLY_ACTIVE_ARCH=YES, active arch=x86_64, VAL ...
swift 2.2 语法 (下)
前言: 1.此文中的语法会根据Swift的升级变动而更新. 2.如果需要请移步 -> swift2.2 语法(上).swift 2.2语法(中) 类的析构函数 swift会自动释放不需要的实例来 ...

006.udp转发包并代理访问服务器总结

006.udp转发包并代理访问服务器总结的更多相关文章

随机推荐

热门专题