tcpserver.c

/*
NAME
       socket - create an endpoint for communication

SYNOPSIS
       #include <sys/types.h>  
       #include <sys/socket.h>

       int socket(int domain, int type, int protocol);

RETURN VALUE
       On  success,  a  file  descriptor  for  the new socket is returned.  On
       error, -1 is returned, and errno is set appropriately.


NAME
       bind - bind a name to a socket

SYNOPSIS
       #include <sys/types.h>
       #include <sys/socket.h>

       int bind(int sockfd, const struct sockaddr *addr,socklen_t addrlen);

RETURN VALUE
       On  success,  zero is returned.  On error, -1 is returned, and errno is
       set appropriately.

NAME
       listen - listen for connections on a socket

SYNOPSIS
       #include <sys/types.h> 
       #include <sys/socket.h>

       int listen(int sockfd, int backlog);

RETURN VALUE
       On  success,  zero is returned.  On error, -1 is returned, and errno is
       set appropriately.

vim tcpserver.c
gcc -o tcpserver tcpserver.c
./tcpserver
netstat -ap|grep tcpserver
*/
#include <sys/types.h>   
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int mian()
{
  int skfd;//socket文件描述符 socket file description 
  socklen_t addrlen;
  int ret;
  char buff[20];

  struct sockaddr_in serveraddr,clientaddr;
  skfd = socket(AF_INEF,SOCK_STREAM,0);
  if(skfd<0)
  {
    perror("socket");
    return -1;  
  }
  //填充网络类型，端口号，ip地址
  serveraddr.sin_family = AF_INEF;//填充网络地址类型 IPv4
  serveraddr.sin_port = htons(55555);//注意 端口号是short htons是字节序转换
  serveraddr.sin_addr.s_addr = 0;//inet_addr(""0,0,0,0);写0表示绑定任意地址
  addrlen = sizeof(serveraddr);
  ret = bind(skfd,(struct sockaddr *)&serveraddr,addrlen);
  if(ret<0)
  {
    perror("bind");
    return -1;  
  } 
  ret = listen(skfd,5);//5表示可以同时连接客户端的数量
  if(ret<0)
  {
    perror("listen");
    return -1;  
  }
  while(1)
  {
    int clientfd;//client文件描述符 client file description 
    clientfd = accept(skfd,(struct sockaddr *)&clientaddr,&addrlen);

    if(clientfd<0)
    {
      perror("accept");
      return -1;  
    }
    printf("ret=%d,ip:%s,port:%d\n",clientfd,inet_ntao(clientaddr.sin_addr,ntohs(clientaddr.sin_port)));
    int recvlen=0;    
    if(clientfd>0)
    {
      while(1)
      {
        memset(buff,0,MSGLEN);
        recvlen = recv(clientfd,buff,10,0);
        if(recvlen==0)
        {
          printf("connect:%d closeed\n",clientfd);
          close(clientfd);
          break;    
        }
        printf("recvlen:%d,%s\n",recvlen,buff);
      }
    }
    close(skfd);
  }
}