雪泥鸿爪－教学中的debug(7)

来自网络课程设计.下面的程序客户端可以向服务器发数据,而服务器发的数据客户端收不到,客户和服务器使用独立的线程进行收包工作.

client.cPP
#include
using namespace std;
DWORD WINAPI ThreadFunc1(LPVOID pParam);
CRITICAL_SECTION m_cs;
WSADATA wsaData;
char recvBuf[50],sendBuf[50];
char peer_ip[20];
SOCKET sockClient;
void main(void)
{
    WORD wVersionRequested;
    int err;
    wVersionRequested = MAKEWORD(1,1);
    ::InitializeCriticalSection(&m_cs);
    if((err = WSAStartup(wVersionRequested,&wsaData))!=0)
        return;
    if(LOBYTE(wsaData.wVersion)!=1 || HIBYTE(wsaData.wVersion)!= 1){
        WSACleanup();
        return;
    }
    SOCKET sockClient = socket(AF_INET,SOCK_STREAM,0);
    SOCKADDR_IN    addrSrv;
    addrSrv.sin_family = AF_INET;
    addrSrv.sin_port=htons(6000);
    while(1){
        cout<<"PLEASE ENTER PEER IP ADDRESS:";
        cin>>peer_ip;
        addrSrv.sin_addr.S_un.S_addr = inet_addr(peer_ip);
        if(connect(sockClient,(SOCKADDR*)&addrSrv,sizeof(SOCKADDR)))
            cout<<"CONNECTION FAILED!\n";
        else {
            cout<<"CONNECTION BUILT!\n";
            break;
        }
    }
    CreateThread(NULL,0,ThreadFunc1,NULL,0,0);
    while(1){
        fgets(sendBuf,20,stdin);
        send(sockClient,sendBuf,strlen(sendBuf)+1,0);
    }
    closesocket(sockClient);
    WSACleanup();
}
DWORD WINAPI ThreadFunc1(LPVOID pParam)
{
    int ret;
//    EnterCriticalSection(&m_cs);
    while(1){
        ret = recv(sockClient,recvBuf,50,0);
        if(ret != SOCKET_ERROR && ret != 0 && ret != 2)
            cout<    }
//    LeaveCriticalSection(&m_cs);
    return 0;
}

server.cpp
#include
#include
using namespace std;
DWORD WINAPI ThreadFunc1(LPVOID pParam);
CRITICAL_SECTION m_cs;
WSADATA wsaData;
SOCKET sockSrv,sockConn;
char recvBuf[50],sendBuf[50];
SOCKADDR_IN addrClient;
void main(void)
{
    WORD wVersionRequested;
    int err;
    wVersionRequested = MAKEWORD(1,1);
    ::InitializeCriticalSection(&m_cs);
    if((err = WSAStartup(wVersionRequested,&wsaData))!=0)
        return;
    if(LOBYTE(wsaData.wVersion)!=1 || HIBYTE(wsaData.wVersion)!=1){
        WSACleanup();
        return;
    }
    sockSrv = socket(AF_INET,SOCK_STREAM,0);
    SOCKADDR_IN addrSrv;
    addrSrv.sin_addr.S_un.S_addr=htonl(INADDR_ANY);
    addrSrv.sin_family=AF_INET;
    addrSrv.sin_port=htons(6000);
    bind(sockSrv,(SOCKADDR*)&addrSrv,sizeof(SOCKADDR));
    listen(sockSrv,5);
    cout<<"SOCKET ESTABLISHED,WAITING FOR CONNECTION...\n";
    int len = sizeof(SOCKADDR);
    sockConn=accept(sockSrv,(SOCKADDR*)&addrClient,&len);
    cout<<"INCOMING CONNECTION: "<    CreateThread(NULL,0,ThreadFunc1,NULL,0,0);
    while(1){
        printf(" server input\n");
        fgets(sendBuf,20,stdin);
        printf("%s\n", sendBuf);
        send(sockConn,sendBuf,strlen(sendBuf)+1,0);
    }
    closesocket(sockConn);
    WSACleanup();
}
DWORD WINAPI ThreadFunc1(LPVOID pParam)
{
    int ret;
//    EnterCriticalSection(&m_cs);
    while(1){
                printf(" server entered\n");
        ret = recv(sockConn,recvBuf,50,0);   
        if(ret != SOCKET_ERROR && ret != 0 && ret != 2)
            cout<    }
//    LeaveCriticalSection(&m_cs);
    return 0;
}


答:
错误在这client端的这两行,主线程看到的是局部的sockClient,而新线程看到的是全局的sockClient.
SOCKET sockClient;
SOCKET sockClient = socket(AF_INET,SOCK_STREAM,0);
新线程的sockClient无效,实际检测recv的返回值,利用WSAGetLastError ()便可以发现该问题