局域网自动搜索服务器

 

两段网上抄的例子, 再加上一些特别的回复. 主要用于自动查找服务器, 方便DEBUG的.
流程是由客户端进行广播, 服务器收到广播后回复自己的IP给客户端, 实现客户端自动查找服务器使用的. 之前发的测试程序被抱怨要慢慢输入服务器IP, 现在搞个自动查找的, 不过没搞完....

客户端

C/C++ code

// UDPBroadcastSend.cpp : Defines the entry point for the console application.
//

#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;  
}  

服务器端:

C/C++ code

// UDPBroadcastRecv.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include<stdio.h>  
#include<winsock2.h>  
#include<windows.h>  
#pragma comment(lib,"ws2_32.lib")  

int _tmain(int argc, _TCHAR* argv[])
{  
    SOCKET sock;  
    sockaddr_in from,a;  
    WSADATA wsdata;  
    bool optval;  
    //启动SOCKET库，版本为2.0  
    WSAStartup(0x0202,&wsdata);  
    optval=true;  
    //然后赋值给两个地址，一个用来绑定套接字，一个用来从网络上的广播地址接收消息；  
    a.sin_family=AF_INET;  
    a.sin_addr.s_addr=INADDR_ANY;  
    a.sin_port=htons(9000);  
    from.sin_family=AF_INET;  
    from.sin_addr.s_addr=INADDR_BROADCAST;  
    from.sin_port=htons(5050);  

    int fromlength=sizeof(SOCKADDR);  
    //用UDP初始化套接字  
    sock=socket(AF_INET,SOCK_DGRAM,0);  
    // 设置该套接字为广播类型，  
    setsockopt(sock,SOL_SOCKET,SO_BROADCAST,(char FAR *)&optval,sizeof(optval));  
    // 把该套接字绑定在一个具体的地址上  
    bind(sock,(sockaddr *)&a,sizeof(sockaddr_in));  
    char buf[256];  
    while(1)  
    {//从广播地址接收消息，注意用来绑定的地址和接收消息的地址是不一样的  
        recvfrom(sock,buf,256,0,(struct sockaddr FAR *)&from,(int FAR *)&fromlength);  
        //Sleep(2000);  
        printf("%sock\n",buf);  
        sendto( sock, buf, strlen(buf) + 1, 0, (struct sockaddr FAR *)&from, fromlength );
        ZeroMemory(buf,256);  
    }  
    return 0;
}