设置UDP发送端口

因特殊需求，需要固定发送端UDP数据的IP地址和端口号，以及接收端IP地址和端口号，程序如下：

#include "stdafx.h"
#include <winsock2.h>

#pragma comment(lib, "ws2_32.lib")

int main()
{ 
	char szData[] = "this is an udp packet";

	WSADATA wsd;

	if(WSAStartup(MAKEWORD(2,2), &wsd)) 
		return INVALID_SOCKET; 

	SOCKET sockClient = socket(AF_INET,SOCK_DGRAM,0);

	SOCKADDR_IN addrLocal;// 发送端IP和端口
	memset(&addrLocal, 0, sizeof(SOCKADDR_IN));
	addrLocal.sin_family = AF_INET; 
	addrLocal.sin_addr.S_un.S_addr = htonl(INADDR_ANY); // 可以指定IP，若该IP不存在则绑定失败 
	addrLocal.sin_port = htons(100); 

	if(bind(sockClient, (SOCKADDR*)&addrLocal, sizeof(SOCKADDR)) == -1)
		return -1; 

	SOCKADDR_IN addrSrv;// 接收端IP和端口
	addrSrv.sin_family = AF_INET; 
	addrSrv.sin_addr.S_un.S_addr = inet_addr("192.168.1.2"); 
	addrSrv.sin_port = htons(200);

	sendto(sockClient, szData, sizeof(szData) / sizeof(char), 0, (SOCKADDR*)&addrSrv, sizeof(SOCKADDR)); 
	closesocket(sockClient);

	WSACleanup();

	return 0;
}