UDP广播socket实现

UDP广播：

const int MAX_BUF_LEN = 255;
int main(int argc, char* argv[])
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
// 启动socket api
wVersionRequested = MAKEWORD( 2, 2 );
err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 )
{
return -1;
}
if ( LOBYTE( wsaData.wVersion ) != 2 ||HIBYTE( wsaData.wVersion ) != 2 )
{
WSACleanup( );
return -1;
}
// 创建socket
SOCKET connect_socket;
connect_socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if(INVALID_SOCKET == connect_socket)
{
err = WSAGetLastError();
printf("socket error! error code is %d\n", err);
return -1;
}
// 用来绑定套接字
SOCKADDR_IN sin;
sin.sin_family = AF_INET;
sin.sin_port = htons(321);
sin.sin_addr.s_addr = 0;
// 用来从网络上的广播地址接收数据
SOCKADDR_IN sin_from;
// 绑定套接字
err = bind(connect_socket, (SOCKADDR*)&sin, sizeof(SOCKADDR));
if(SOCKET_ERROR == err)
{
err = WSAGetLastError();
printf("bind error! error code is %d\n", err);
return -1;
}
int nAddrLen = sizeof(SOCKADDR);
char buff[MAX_BUF_LEN] = "";
int nLoop = 0;
while(1)
{
// 接收数据
int nSendSize = recvfrom(connect_socket, buff, MAX_BUF_LEN, 0, (SOCKADDR*)&sin_from, &nAddrLen);
if(SOCKET_ERROR == nSendSize)
{
err = WSAGetLastError();
printf("recvfrom error! error code is %d/n", err);
return -1;
}
buff[nSendSize] = '\0';
printf("Recv: %s\n", buff);
}
return 0;
}

#include "stdafx.h"
#include<stdio.h>
#include <iostream>
#include<winsock2.h>
#include<windows.h>
#pragma comment(lib,"ws2_32.lib")
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
SOCKET sock;
sockaddr_in addrto;
WSADATA wsdata;
bool bsocket;
char smsg[100] = {0};
cout<<"input what message to send\n:"<<endl;
cin>>smsg;
//启动SOCKET库，版本为2.0
WSAStartup(0x0202,&wsdata);
sock=WSASocket(AF_INET,SOCK_DGRAM,0,NULL,0,WSA_FLAG_OVERLAPPED);
bsocket=true;
//然后赋值给地址，用来从网络上的广播地址接收消息；
addrto.sin_family=AF_INET;
addrto.sin_addr.s_addr=INADDR_BROADCAST;
addrto.sin_port=htons(9000);
bool opt=true;
//设置该套接字为广播类型，
setsockopt(sock,SOL_SOCKET,SO_BROADCAST,(char FAR *)&opt,sizeof(opt));
int nlen=sizeof(addrto);
char buf[100] = {0};
while(1)
{
addrto.sin_family=AF_INET;
addrto.sin_addr.s_addr=INADDR_BROADCAST;
addrto.sin_port=htons(9000);
Sleep(1000);
//从广播地址发送消息
int ret=sendto(sock,smsg, strlen(smsg) + 1,0,(sockaddr*)&addrto,nlen);
if(ret==SOCKET_ERROR)
{
printf("%d/n",WSAGetLastError());
}
else
{
printf("It'sock OK.\n");
}
ret = recvfrom( sock, buf, sizeof(buf), 0, (sockaddr*)&addrto, &nlen );
if (SOCKET_ERROR == ret)
{
printf("error on recv after send!\n");
}
else
{
printf("recv after send: %s\n", buf);
}
}
return 0;
}

转载自：https://my.oschina.net/lopo/blog/260891;(转载请注明)