TCP套接字服务器不发送

Question

I have this code, I run client from virtual machine on same PC it can connect but it will never receive LOGIN message, what could be the cause?

Not sure about send flags argument is set right.

static const char *LOGIN = "LOGIN\n";

int main()
{
    int s = socket(AF_INET, SOCK_STREAM, 0);

    struct sockaddr_in addr;
    socklen_t addrlen = sizeof(addr);

    //initialize structure
    bzero(&addr, addrlen);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(6666);
    addr.sin_addr.s_addr = htonl(INADDR_ANY);

    bind(s, (struct sockaddr *)&addr, addrlen);
    listen(s, 1);

    struct sockaddr_in client_addr;
    socklen_t client_addrlen = sizeof(client_addr);
    int c = accept(s, (struct sockaddr *)&client_addr, &client_addrlen);

    char *msg = new char[15];

        //print client address
        char * buf = new char[16];
        inet_ntop(AF_INET, &(client_addr.sin_addr.s_addr), buf, 16);
        cout << "Client connected: " << buf << endl;
        cout << "---------------------" << endl;

        send(c, LOGIN, sizeof(LOGIN), 0);

    close(c);
    close(s);
    return 0;
}

Answer 1

You have to change:

static const char *LOGIN = "LOGIN\n";

to:

static const char LOGIN[] = "LOGIN\n";

and the send call to:

send(c, LOGIN, sizeof(LOGIN)-1, 0);

The original call passed 4 (if on 32-bit system) because the sizeof was applied on pointer rather than on the string. The -1 in the fixed version subtracts the terminating '0' from the string.