socket网络连接

Socket Client Example

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <netinet/in.h>

const int port = 5000;                    //服务器开放的端口号
const char* ip = "10.10.12.95";              //服务器的ip

int main()
{
	  //创建套接字,即创建socket 
	  int clt_sock = socket(AF_INET, SOCK_STREAM, 0); 
	  if(clt_sock < 0)
	  {
		  //创建失败
		  perror("socket");
		  return 1;
	  }

	  //绑定信息，即命名socket 
	  struct sockaddr_in addr; 

	  addr.sin_family = AF_INET;    // ipv4协议族
	  addr.sin_port = htons(port);    // 指定目标机端口 并转化位网络自己顺序
	  addr.sin_addr.s_addr = inet_addr(ip);     

         //inet_addr函数将把用点分十进制字符串表示的IPv4地址转化为用网络字节序整数表示的IPv4地址 

          socklen_t addr_len = sizeof(addr);

	  int connect_fd = connect(clt_sock, (struct sockaddr*)&addr, addr_len);
 

 //发起连接 
         int connect_fd = connect(clt_sock, (struct sockaddr*)&addr, addr_len); 
         if(connect_fd < 0) 
         { 
                  perror("connect"); 
                  return 2; 
         } 
        while(1)
      {
          memset(buf, '\0', sizeof(buf));
          printf("client please enter: ");
          fflush(stdout);
          ssize_t size = read(0, buf, sizeof(buf) - 1);
          if(size > 0)
          {
              buf[size - 1] = '\0';
          }
          else if(size == 0)
          {
              printf("read is done...\n");
              break;
          }
          else
          {
              perror("read");
              return 4;
          }
          write(clt_sock, buf, strlen(buf));
          size = read(clt_sock, buf, sizeof(buf));
          if(size > 0)
          {
               buf[size] = '\0';
          }
          else if(size == 0)
          {
              printf("read is done...\n");
              break;
          }
          else 
          {
              perror("read");
              return 5;
          }
          printf("server: %s\n", buf);
       }
      close(clt_sock);
      return 0;
}

Socket Server Example

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <netinet/in.h>

const int port = 5000;
const char* ip = "10.10.12.95"; 

int main()
{
	  //创建套接字,即创建socket 
	  int ser_sock = socket(AF_INET, SOCK_STREAM, 0); 
	  if(ser_sock < 0)
	  {
		  //创建失败
		  perror("socket");
		  return 1;
	  }

	  //绑定信息，即命名socket 
	  struct sockaddr_in addr; 
	  addr.sin_family = AF_INET; 
	  addr.sin_port = htons(port); 
	  addr.sin_addr.s_addr = inet_addr(ip); 

	  if(bind(ser_sock, (struct sockaddr*)&addr, sizeof(addr)) < 0) 
	  {	            
    	       //绑定失败 
	       perror("bind"); 
	       return 2; 	   
	  } 

	  //监听socket
	  int listen_sock = listen(ser_sock, 5);    // 5为内核为该套接字排队的最大连接个数
	  if(listen_sock < 0)
	  {
		  //监听失败
		  perror("listen");
		  return 3;
	  }

         //接受连接
	  //系统调用从listen监听队列中接受一个连接
	  //int accept(int sockfd, struct sockaddr* addr, socklen_t* addrlen)
	  //sockfd参数是执行过listen系统调用的监听socket；addr参数用来获取被
	  //接受连接的远端socket地址，该socket地址的长度由addrlen参数指出
	  //accept成功时返回一个新的连接socket，该socket唯一的标识了被接受
	  //的这个连接，服务器可通过读写该socket来与被接受连接对应的客户端通信

          struct sockaddr_in peer;
	  socklen_t peer_len = sizeof(struct sockaddr_in);     // 这个初始化很重要
	  char buf[1024];
	  int accept_fd = accept(ser_sock, (struct sockaddr*)&peer, &peer_len);  
          //在调用函数accept()的时候，服务器就处于睡眠状态，当客户机发来一个请求并完成三次握手后accept()函数苏醒并且返回表示客户端socket的描述符。

	  if(accept_fd < 0)
	  {
		  perror("accept");
		  return 4;
	  }
	  else
	  {
		  printf("connected with ip: %s  and port: %d\n", inet_ntop(AF_INET,&peer.sin_addr, buf, 1024), ntohs(peer.sin_port));
		
	  }

	  while(1)
	  {
		  memset(buf, '\0', sizeof(buf));
		  ssize_t size = read(accept_fd, buf, sizeof(buf) - 1);
		  if(size > 0)
		  {
			  printf("client#: %s\n", buf);
		  }
		  else if(size == 0)
		  {
			  printf("read is done...\n");
			  break;
		  }
		  else 
		  {
			  perror("read");
			  break;
		  }   


                  printf("server please enter: ");
		  fflush(stdout);
                  size = read(0, buf, sizeof(buf) - 1);
		  if(size > 0)
		  {
			  buf[size - 1] = '\0';
		  }
		  else if(size == 0)
		  {
			  printf("read is done...\n");
			  break;
		  }
		  else
		  {
			  perror("read");
			  break;
		  }	  
		  write(accept_fd, buf, strlen(buf));
	  }
		close(ser_sock);
	  return 0;
}

   
另：

 // 另一种读数据的方法
 while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0)    
    {  
         ....
    }   
  
  if(n < 0)  
    {  
        printf("\n Read error \n");  
    }