🚀 go-pugleaf

"Feico" <feicorem0veth1s@gmx.net> wrote in message
news:mk4kc0lf2ku8qbgk2n98eav00l9b0552u5@4ax.com...

> I'm trying to write a program that can perform functions like Telnet.
> That is, it must open a connection to a server (POP3 or SMTP in
> my case) and exchange commands.

You do not need Telnet for that.

> My biggest success was #include <winsock2.h>. This produced a host of
interesting functions.

If I were you, I would just use a pre-made TCP component instead of trying
to do everything manually.  Either Borland-provided or third-party, it
doesn't really matter.

> I tried them in opposite order, since connect appeared not to work
> without a preceding socket, and socket would not work without a
> preceding WSAStartup, etc.

That is correct.

> Still some parameters are enigmatic to me. For example, the first
> parameter of socket is an Address family specification, but nobody
> knows what an Address family specification is.

Use AF_INET.

> But let's be brief. Telnet performs a command like:
>   OPEN [domain name] [port]
> for example:
>   OPEN pop.smurf.com 110
>
> How is this done in a C program?

Use connect(), for example:

    #include <winsock2.h>

    char *host = "pop.smurf.com";

    WSADATA WSAData = {0};
    if( WSAStartup(MAKEWORD(2, 0), &WSAData) == 0 )
    {
        unsigned long HostAddr = inet_addr(host);
        if( HostAddr == INADDR_NONE )
        {
            hostent *pHost = gethostbyname(host);
            if( pHost )
                HostAddr = inet_addr(pHost->h_addr);
        }

        if( HostAddr != INADDR_NONE )
        {
            SOCKET sock = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
            if( sock )
            {
                unsigned long enabled = 0;
                if( ioctlsocket(sock, FIONBIO, &enabled) == 0 )
                {
                    sockaddr_in addr = {0};
                    addr.sin_addr.s_addr = HostAddr;
                    addr.sin_port = 110;
                    if( connect(sock, (sockaddr*)&addr, sizeof(addr)) == 0 )
                    {
                        // read/write the socket as needed...
                        shutdown(sock, SD_SEND);
                    }
                }
                closesocket(sock);
            }
        }
        WSACleanup();
    }

> It cannot be that complicated.

You are making it more complicated for yourself by trying to do everything
manually without understanding what you are doing to begin with.


Gambit