server_udp.cpp

udp 的连接实例

#include <stdio.h>
#include "winsock2.h"
#include "time.h"
#include "stddef.h"
#include <iostream>
using namespace std;


int main() {
  
//-----------------------------------------------
// Initialize Winsock
  WSADATA wsaData;
  SOCKET mySocket;
  sockaddr_in serverAdd;
  sockaddr_in clientAdd;
  int Port = 27015;
  char RecvBuf[5];
  int  BufLen=5;
  WSAStartup(MAKEWORD(2,2), &wsaData);
  int clientAddSize = sizeof(clientAdd);
//-----------------------------------------------
// Create a socket  
  mySocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); 
  serverAdd.sin_family = AF_INET;
  serverAdd.sin_port = htons(Port);
  serverAdd.sin_addr.s_addr = htonl(INADDR_ANY);
//-----------------------------------------------
// Bind the socket to any address and the specified port.
  int rval=bind(mySocket, (SOCKADDR *)&serverAdd, sizeof(serverAdd));
//-----------------------------------------------
//error checking
  if(rval < 0)
	{
		cout << "binding error"<<endl;
		return 0;
	}
//-----------------------------------------------
// Call the recvfrom function to receive datagrams
// on the bound socket.

      printf("the udp_sercer is receiving ...\n");

      recvfrom(mySocket, RecvBuf,  BufLen,   0, 
	  (SOCKADDR *)&clientAdd, &clientAddSize);
//-----------------------------------------------
//Show the request of the client	  
	  printf("The client request:");
	  for(int i=0;i<5;i++){cout<<RecvBuf[i];}
	  cout<<endl;
//-----------------------------------------------
// Close the socket when finished receiving datagrams
      printf("Finished receiving & Closing socket.\n");
	  struct tm *str;
	  time_t setime;
	  setime=time(0);
	  str=localtime(&setime);
	  printf("The sever is sending the time.\n");
	  sendto(mySocket,asctime(str),strlen(asctime(str))+1,0,(SOCKADDR *) &clientAdd,sizeof(clientAdd));
	  closesocket(mySocket);
//-----------------------------------------------
// closed
  printf("the socket is closed!\n");
  WSACleanup();
  
  return 0;
}