udpreceiver.cpp

“网络安全技术实践与代码详解”实例代码

/* ==========================================================
*     开发人员：牛冠杰
*     当前版本：1.0
*     创建时间：2006-12-05
*     修改时间：2006-12-05
*     功能说明：UDP通信中的接收端程序，采取Winsock编程方法
*     使用方法：UDPReceiver [port]

*/
#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>
#pragma  comment (lib, "ws2_32.lib")

#define MSG_BUFFER_LENGTH 2048 // 接收数据的最大长度

int main(int argc, char **argv)
{
	WSADATA   wsd;
	SOCKET    recv_s;
	char      *recvbuf;
	int       ret;
	int       port;
	SOCKADDR_IN localaddr;
	SOCKADDR_IN destaddr;
	int destlen = sizeof(destaddr);

	if(argc != 2)
	{
		printf("usage: %s [port]",argv[0]);
		exit(1);
	}
	port=atoi(argv[1]); // 获得端口号
    
	// 初始化Winsock库
	if(WSAStartup(MAKEWORD(2,2),&wsd) != 0)
	{
		printf("WSAStartup error!\n");
		exit(1);
	}
    // 创建UDP套接字
	recv_s = socket(AF_INET, SOCK_DGRAM, 0);
	if(recv_s == INVALID_SOCKET)
	{
		printf("socket() errror : %d\n",WSAGetLastError());
		exit(1);
	}

    // 对本地地址结构进行设置
	localaddr.sin_family = AF_INET;
	localaddr.sin_port = htons((u_short)port);
	localaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	
    // 对套接字进行绑定
	if(bind(recv_s, (SOCKADDR *)&localaddr, sizeof(localaddr)) == SOCKET_ERROR)
	{
		printf("bind() error: %d\n", WSAGetLastError());
		exit(1);
	}

	printf("在端口 %d 开始接收消息...\n",port);

	recvbuf = new char[MSG_BUFFER_LENGTH]; // 分配接收缓存区
	int recvlen = MSG_BUFFER_LENGTH;
    // 开始接收消息
	while(1)
	{
		ret = recvfrom(recv_s, recvbuf, recvlen, 0,
			(SOCKADDR*)&destaddr, &destlen);
		if(ret == SOCKET_ERROR)
		{
			printf("recvfrom() error: %d\n",WSAGetLastError());
			exit(1);
		}
		else if(ret == 0)
		{
			break;
		}
		else
		{
			recvbuf[ret]='\0';
			printf("收到主机 %s 消息: %s\n",inet_ntoa(destaddr.sin_addr),recvbuf);
		}

	}
	closesocket(recv_s);
	delete recvbuf;
	WSACleanup();
	return 0;
}