Question

I’m trying to make simple IMAP client using winsock/OpenSSL, is this possible without additional libraries? If so, how to send request and get responce? Server is responding only once,even without request,after that i’m sending request and application stuck at SSL_read(..) function,than timeout and BYE.How to make proper request?

bool RequestQueue(const char* serverName)
{
    SOCKET      hSocket = INVALID_SOCKET;
    char        receiveBuf[512];
    ZeroMemory(receiveBuf,512); 
    char        requestBuf[512];
    ZeroMemory(requestBuf,512); 
    sockaddr_in sockAddr = {0};
    bool        bSuccess = true;

    //SSL
    SSL* ssl;
    SSL_CTX* ctx;

    try
    {       
        //Look up hostname and fill sockaddr_in structure
        cout<< "Looking up hostname "<<serverName<<"...";
        FillSockAddr(&sockAddr,serverName,IMAP_SERVER_PORT);
        cout<< "found.\n";

        //creating socket
        cout<<"Creating socket..";
        if((hSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)) == INVALID_SOCKET)
            throw exception("could not create socket!");
        cout<<"created.\n";

            //Connect to server
        cout<<"Attempting to connect to "<< inet_ntoa(sockAddr.sin_addr)
            <<":"<<IMAP_SERVER_PORT<<" ...";
        if(connect(hSocket,(sockaddr*)(&sockAddr),sizeof(sockAddr))!= 0)
            throw exception("could not connect!");

        cout<<"connected\n";

        ctx = SSL_CTX_new(SSLv23_client_method());
        if(!ctx)
            throw exception("SSL_CTX_new error");

        ssl = SSL_new(ctx);
        SSL_CTX_free(ctx);
        if(!ssl)
            throw exception("ssl initializing error");

        SSL_set_fd(ssl,hSocket);
        if(SSL_connect(ssl) != 1)
            throw exception("SSL_connect error");

        int reqLen;
        int retLen;
        cout<<"==============\n";
        cout<<"====begin=====\n";
        cout<<"==============\n";

        retLen = SSL_read(ssl,receiveBuf,sizeof(receiveBuf));
        if(retLen<0)
            throw exception("SSL_read error.");
        cout<<"S: "<<receiveBuf;

        strcpy(requestBuf,"a001 CAPABILITY");
        reqLen = strlen(requestBuf);
        SSL_write(ssl,requestBuf,reqLen);
        cout<<"C: "<<requestBuf<<endl;  

        ZeroMemory(receiveBuf,sizeof(receiveBuf));
        retLen = SSL_read(ssl,receiveBuf,sizeof(receiveBuf));
        if(retLen<0)
            throw exception("SSL_read error.");

        cout<<"S: "<<receiveBuf;                    
    }
    catch(exception e)
    {
        cout<<"Error : "<<e.what()<<endl;
    }
    if(hSocket != INVALID_SOCKET)
    {
        SSL_shutdown(ssl);
        closesocket(hSocket);
        SSL_free(ssl);      
    }

    return bSuccess;
}

Answer 1

I didn’t analyze your code deeply, but I can see one obvious issue.
According to the RFC 3501:

All interactions transmitted by client and server are in the form of
lines, that is, strings that end with a CRLF. The protocol receiver
of an IMAP4rev1 client or server is either reading a line, or is
reading a sequence of octets with a known count followed by a line.

In your code you’re not terminating the command with CRLF. Try replacing

strcpy(requestBuf,"a001 CAPABILITY");

with

strcpy(requestBuf,"a001 CAPABILITY\r\n");

Also, you’d better start without SSL and add it later – this will simplify debugging a lot (i.e. with Wireshark).