【Socket】简单的回声服务器实现

#include 
#include 
#include 
#include 
#include 
#include 
#include 


#define SERVER_PORT 666

int main(void){

  int sock;//信箱

  struct sockaddr_in server_addr;


  //创建信箱
  sock = socket(AF_INET,SOCK_STREAM,0);
  
  
  //清空标签
  bzero(&server_addr,sizeof(server_addr));  
  //写上地址和端口号
  server_addr.sin_family = AF_INET;   //选择协议族ipv4
  server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//监听本地所有IP地址-几个网卡就有几个IP地址
  server_addr.sin_port = htons(SERVER_PORT);  //绑定端口号

  //实现标签贴到收信的信箱上
  bind(sock,(struct sockaddr*)&server_addr,sizeof(server_addr));

  //邮箱一次性只能接收128封信件
  listen(sock,128);

  printf("等待客户端链接\n");

  int done = 1;
  
  while(done){
    struct sockaddr_in client;
    
    int client_socket;    
    int len;

    char client_ip[64];
    
    char buf[256];

    socklen_t client_addr_len;

    client_addr_len = sizeof(client); 
      
    client_socket = accept(sock,(struct sockaddr*)&client,&client_addr_len);

    printf("客户端地址:%s\t端口:%d\n",inet_ntop(AF_INET,&client.sin_addr.s_addr,client_ip,sizeof(client_ip)),ntohs(client.sin_port));

    //读取数据
    len = read(client_socket,buf,sizeof(buf)-1);

    buf[len] = '\n';//read读过来的数据不会自动加字符串结束符

    printf("收到[%d]：%s\n",len,buf);

    len = write(client_socket,buf,len);//发回去

    printf("写完，len:%d",len);

    close(client_socket);
  }

  return 0;
}

#include 
#include 
#include 
#include 
#include 
#include 

#define SERVER_PORT 666
#define SERVER_IP "127.0.0.1"


int main(int argc, char* argv[]) {

  int sockfd;
  char* message;

  struct sockaddr_in servaddr;

  int n;

  char buf[64];

  //echo_client "xxxx"   ——所以判断是否为2
  if (argc != 2) {
    fputs("Usage: ./echo_client message \n",stderr);
    exit(1);
  }

  message = argv[1];
  printf("message: %s\n",message);


  sockfd = socket(AF_INET,SOCK_STREAM,0);

  memset(&servaddr,'\0',sizeof(struct sockaddr_in));

  servaddr.sin_family = AF_INET;

  //inet_pton(AF_INET,SERVER_IP,&servaddr.sin_addr);
  inet_pton(AF_INET, SERVER_IP, &servaddr.sin_addr);
  servaddr.sin_port = htons(SERVER_PORT); //转换为网络字节序

  connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr));

  write(sockfd,message,strlen(message));

  n = read(sockfd, buf, sizeof(buf)-1);

  if (n > 0) {
    buf[n] = '\n';
    printf("receive: %s\n",buf);
  } else {
    perror("error!");
  }

  printf("finished!\n");
  close(sockfd);

  return 0;
}