C++を使用して簡単なTCPサーバの作成を実現する方法

シンプルなTCPサーバ実装

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

#define SERVER_PORT 7000
void sys_err(const char *str)
{
  perror(str);
  exit(1);
}
int main(int agrc, char *argv[]){
  int ret;
  char buf[BUFSIZ];
  //        
  int lfd = 0, cfd=0;
  //   addr      
  struct sockaddr_in server_addr, client_addr;
  socklen_t client_addr_len;
  
  server_addr.sin_family = AF_INET;
  server_addr.sin_port = htons(SERVER_PORT);
  server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
  
  //   socket
  lfd = socket(AF_INET, SOCK_STREAM, 0);
  if(lfd == -1){
    sys_err("socket error");
  }
  //     
  bind(lfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
  //     
  listen(lfd, 128);
  
  //     
  client_addr_len = sizeof(client_addr);
  cfd = accept(lfd, (struct sockaddr *)&client_addr, &client_addr_len);
  if (cfd == -1){
    sys_err("accept error");
  }
  
  while(1){
      //     
      ret = read(cfd, buf, sizeof(buf));
      write(STDOUT_FILENO, buf, ret);
      for (int i=0; i