内网穿透 TCP打洞 C语言实现

左手的ㄟ右手 2022-11-15 05:48 235阅读 0赞

[https://blog.csdn.net/soralaro/article/details/86696349][https_blog.csdn.net_soralaro_article_details_86696349]

# 内网穿透 TCP打洞 C语言实现 #

时间 2017-03-29

标签 [socket][] [c语言][c] [打洞][Link 1] [穿透][Link 2] 栏目 [系统网络][Link 3]

*原文* http://blog.csdn.net/wuzuyu365/article/details/68068133

上篇文章中做了UDP打洞，这篇当然就会是TCP打洞了，两个处于不同内网的两台机器如何通过TCP/IP协议进行链接通讯呢？这其实跟UDP打洞差不多，基本步骤是这个样子的。  
假设我们有两台处于不同内网的两台机器A和B和一台众所周知外网IP的服务器S，而机器A中运行着通讯的服务端程序B运行着通讯的客户端程序，那么  
  
  
1、A连接S，S记录A的外网IP与通讯的端口  
2、B连接S  
3、S将A与此通讯的端口号返回给A  
4、S将A与此连接的IP与端口号返回给B  
5、A在程序中将服务绑定并侦听在从S返回的端口  
6、B使用从S返回的IP与端口连接A  
  
  
这样A与B就成功连接了,这里需要注意的一点就是两个socket在同一个端口绑定的问题，socket提供了setsockopt函数，其中参数SO\_REUSEADDR可以解决这个问题  
  
  
下面是c语言代码示例  
  
  
S中的程序

#include <stdio.h>
    #include <sys/socket.h>
    #include <sys/types.h>
    #include <stdlib.h>
    #include <string.h>
    #include <errno.h>
    #include <arpa/inet.h>
    #include <netinet/in.h>
     
    typedef struct sockaddr SA;
    typedef struct sockaddr_in SA_IN;
     
    typedef struct
    {
     struct in_addr ip;
     int port;
    }IP; //记录ip与端口
     
    int main(int argc,char **argv)
    {
     SA_IN server,addr;
     int sockfd;
     IP ip;
     char s;
     socklen_t addrlen=sizeof(SA_IN);
     
     sockfd=socket(AF_INET,SOCK_STREAM,0);
     if(sockfd == -1)
     {
      perror("socket");
      return -1;
     }
     bzero(&server,sizeof(SA_IN));
     server.sin_port=htons(8888);
     server.sin_family=AF_INET;
     server.sin_addr.s_addr=INADDR_ANY;
     if(bind(sockfd,(SA *)&server,sizeof(SA_IN)) == -1)
     {
      perror("bind");
      return -1;
     }
     if(listen(sockfd,20) == -1)
     {
      perror("listen");
      return -1;
     }
     
     while(1)
     {
      int newfd[2];
     
      newfd[0]=accept(sockfd,(SA *)&addr,&addrlen);
      //接收两个心跳包
      recv(newfd[0],&s,sizeof(char),0);
      memcpy(&ip.ip,&addr.sin_addr,sizeof(struct in_addr));
      ip.port=addr.sin_port;
      printf("%s\t%d OK\n",inet_ntoa(ip.ip),ntohs(ip.port));
     
      newfd[1]=accept(sockfd,(SA *)&addr,&addrlen);
      printf("%s\t%d OK\n",
        inet_ntoa(addr.sin_addr),ntohs(addr.sin_port));
     
      send(newfd[0],&ip,sizeof(IP),0);
      send(newfd[1],&ip,sizeof(IP),0);
     
      close(newfd[0]);
      close(newfd[1]);
     }
     
     return 0;
    }

A中的程序

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <sys/socket.h>
    #include <sys/types.h>
    #include <arpa/inet.h>
     
    #define SER "xxx.xxx.xxx.xxx"
    #define PORT 8888
     
    typedef struct
    {
     struct in_addr ip;
     int port;
    }IP; //ip与端口
     
    typedef struct sockaddr SA;
    typedef struct sockaddr_in SA_IN;
     
    //回射服务
    void echo_ser(int sockfd)
    {
     char buf[1024];
     
     while(1)
     {
      bzero(buf,sizeof(buf));
      //接收B发来的数据
      recv(sockfd,buf,sizeof(buf)-1,0);
      printf("%s",buf);
      //向B发送数据
      send(sockfd,buf,strlen(buf),0);
     
      buf[strlen(buf)-1]='\0';
      if(strcmp(buf,"exit") == 0)
       break;
     }
    }
     
    int main(int argc,char **argv)
    {
     int sockfd,sockfd2;
     SA_IN server,addr;
     IP ip;
     socklen_t addrlen=sizeof(SA_IN);
     char s='a';
     int flags=1;
     
     sockfd=socket(AF_INET,SOCK_STREAM,0);
     
     bzero(&server,sizeof(SA_IN));
     server.sin_family=AF_INET;
     server.sin_addr.s_addr=inet_addr(SER);
     server.sin_port=htons(PORT);
     
     if(setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&flags,sizeof(int)) == -1)
      perror("setsockopt sockfd");
     connect(sockfd,(SA *)&server,sizeof(SA_IN));
     send(sockfd,&s,sizeof(char),0);
     recv(sockfd,&ip,sizeof(IP),0);
     close(sockfd);
     
     sockfd2=socket(AF_INET,SOCK_STREAM,0);
     if(sockfd2 == -1)
      perror("sockfd2");
     if(setsockopt(sockfd2,SOL_SOCKET,SO_REUSEADDR,&flags,sizeof(int)) == -1)
      perror("setsockopt sockfd2");
     server.sin_addr.s_addr=INADDR_ANY;
     server.sin_port=ip.port;
     if(bind(sockfd2,(SA *)&server,sizeof(SA_IN)) == -1)
      perror("bind sockfd");
     if(listen(sockfd2,20) == -1)
      perror("listen");
     
     echo_ser(accept(sockfd2,(SA *)&addr,&addrlen));
     
     close(sockfd2);
     
     return 0;
    }

B中的程序

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <sys/socket.h>
    #include <sys/types.h>
    #include <arpa/inet.h>
     
    #define SER "xxx.xxx.xxx.xxx"
    #define PORT 8888
     
    typedef struct
    {
     struct in_addr ip;
     int port;
    }IP; //ip与端口
     
    typedef struct sockaddr SA;
    typedef struct sockaddr_in SA_IN;
     
    void echo_cli(int sockfd)
    {
     char buf[1024];
     
     while(1)
     {
      bzero(buf,sizeof(buf));
      printf(">");
      fflush(stdout);
      fgets(buf,sizeof(buf)-1,stdin);
      send(sockfd,buf,strlen(buf),0);
     
      bzero(buf,sizeof(buf));
      recv(sockfd,buf,sizeof(buf)-1,0);
      printf("%s",buf);
      buf[strlen(buf)-1]='\0';
      if(strcmp(buf,"exit") == 0)
       break;
     }
    }
     
    int main(int argc,char **argv)
    {
     int sockfd,sockfd2;
     SA_IN server,addr;
     IP ip;
     socklen_t addrlen=sizeof(SA_IN);
     
     sockfd=socket(AF_INET,SOCK_STREAM,0);
     
     bzero(&server,sizeof(SA_IN));
     server.sin_family=AF_INET;
     server.sin_addr.s_addr=inet_addr(SER);
     server.sin_port=htons(PORT);
     
     connect(sockfd,(SA *)&server,sizeof(SA_IN));
     recv(sockfd,&ip,sizeof(IP),0);
     close(sockfd);
     
     sockfd2=socket(AF_INET,SOCK_STREAM,0);
     server.sin_addr=ip.ip;
     server.sin_port=ip.port;
     while(connect(sockfd2,(SA *)&server,sizeof(SA_IN)) == -1)
      perror("connect");
     
     echo_cli(sockfd2);
     
     close(sockfd2);
     return 0;
    }

[https_blog.csdn.net_soralaro_article_details_86696349]: https://blog.csdn.net/soralaro/article/details/86696349
[socket]: http://www.voidcn.com/tag/socket
[c]: http://www.voidcn.com/tag/c%E8%AF%AD%E8%A8%80
[Link 1]: http://www.voidcn.com/tag/%E6%89%93%E6%B4%9E
[Link 2]: http://www.voidcn.com/tag/%E7%A9%BF%E9%80%8F
[Link 3]: http://www.voidcn.com/column/network