c語言socket多線程編程限制客戶端連接數

2020-01-26 15:40:41

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先上一些多線程需要使用的函數定義：

DWORD WINAPI ProcessClientRequests(LPVOID lpParam) //新線程將會執行的函數定義
{
return 0;
}

HANDLE handler=CreateThread(NULL, 0, ProcessClientRequests, &clientsocket, 0, NULL); //這里比較簡單，&clientsocket是個指針，是從主線程傳入新線程的參數

WaitForMultipleObjects(MAXCLIENTS, threads, TRUE, INFINITE); //用來阻塞主線程，直到所有創建的子線程都完成任務為止，才繼續執行后面的代碼

for(int i=0;i<MAXCLIENTS; i++)
{
CloseHandle(threads[i]); //創建的每個子線程的HANDLE都會被保存在HANDLE數組中，這個函數用于關閉各個handle所對應的線程空間
}

服務器端程序

主線程代碼如下：

復制代碼代碼如下:

#define MAXCLIENTS 3 //宏定義，最多3個客戶端連接

int main()
{
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 2), &wsaData);
    HANDLE threads[MAXCLIENTS];

SOCKET s=socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);

    sockaddr_in sockaddr;
    sockaddr.sin_family=PF_INET;
    sockaddr.sin_addr.S_un.S_addr=inet_addr("127.0.0.1");
    sockaddr.sin_port=htons(9000);
    bind(s, (SOCKADDR*)&sockaddr, sizeof(SOCKADDR));

listen(s, 1);

printf("listening on port [%d]./n", 9000);

    int existingClientCount=0;
    while(TRUE)
    {
        SOCKADDR clientAddr;
        int size=sizeof(SOCKADDR);

        SOCKET clientsocket;
        clientsocket=accept(s, &clientAddr, &size);
        printf("***SYS***    New client touched./n");

        if(existingClientCount<MAXCLIENTS)       //判斷是否已經超出最大連接數了
        {
            threads[existingClientCount++]=CreateThread(NULL, 0, ProcessClientRequests, &clientsocket, 0, NULL); //啟動新線程，并且將socket傳入
        }
        else
        {
            char* msg="Exceeded Max incoming requests, will refused this connect!/r/n";
            send(clientsocket, msg, strlen(msg)+sizeof(char), NULL);       //發送拒絕連接消息給客戶端
            printf("***SYS***    REFUSED./n");
            closesocket(clientsocket);                                     //釋放資源
            break;
        }
    }

printf("Maximize clients occurred for d%./r/n", MAXCLIENTS);

WaitForMultipleObjects(MAXCLIENTS, threads, TRUE, INFINITE); //等待所有子線程，直到完成為止

    closesocket(s);
    for(int i=0;i<MAXCLIENTS; i++)
    {
        CloseHandle(threads[i]);                                           //清理線程資源
    }

    WSACleanup();

printf("Cleared all./r/n");

getchar();

exit(0);
}

子線程函數定義

復制代碼代碼如下:

DWORD WINAPI ProcessClientRequests(LPVOID lpParam)
{
SOCKET* clientsocket=(SOCKET*)lpParam; //這里需要強制轉換，注意：指針類型的

    char* msg="Hello, my client./r/n";
    send(*clientsocket, msg, strlen(msg)+sizeof(char), NULL);
    printf("***SYS***    HELLO./n");

    while(TRUE)
    {
        char buffer[MAXBYTE]={0};
        recv(*clientsocket, buffer, MAXBYTE, NULL);
        if(strcmp(buffer, "exit")==0)
        {
            char* msg_bye="Bye./r/n";
            send(*clientsocket, msg_bye, strlen(msg_bye)+sizeof(char), NULL);
            break;
        }
        printf("***Client***    %s/n", buffer);
    }

    closesocket(*clientsocket);

return 0;
}