(C) IMAP Use Existing SSH Tunnel

Demonstrates how to connect to an IMAP server using an existing SSH tunnel. This creates a new channel within the SSH tunnel, which can be a TCP or TLS connection, and is connected to a remote IMAP server through port forwarding.

Note: This example requires Chilkat v11.0.0 or greater.

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#include <C_CkSocket.h>
#include <C_CkImap.h>
#include <C_CkEmail.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSocket tunnel;
    const char *sshHostname;
    int sshPort;
    HCkImap imap;
    int msgCount;
    int upperBound;
    HCkEmail email;
    int i;
    BOOL bUid;

    success = FALSE;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    tunnel = CkSocket_Create();

    sshHostname = "sftp.example.com";
    sshPort = 22;

    // Connect to an SSH server and establish the SSH tunnel:
    success = CkSocket_SshOpenTunnel(tunnel,sshHostname,sshPort);
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(tunnel));
        CkSocket_Dispose(tunnel);
        return;
    }

    // Authenticate with the SSH server via a login/password
    // or with a public key.  
    // This example demonstrates SSH password authentication.
    // Note: This is not authenticating with the IMAP server, it is
    // for authenticating with the SSH server, which is separate.
    success = CkSocket_SshAuthenticatePw(tunnel,"mySshLogin","mySshPassword");
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(tunnel));
        CkSocket_Dispose(tunnel);
        return;
    }

    // OK, the SSH tunnel is setup.  Now open a channel within the tunnel.
    // Once the channel is obtained, the Socket API may
    // be used exactly the same as usual, except all communications
    // are sent through the channel in the SSH tunnel.
    // Any number of channels may be created from the same SSH tunnel.
    // Multiple channels may coexist at the same time.

    imap = CkImap_Create();

    // Let the IMAP object also use the SSH tunnel
    success = CkImap_UseSshTunnel(imap,tunnel);
    if (success == FALSE) {
        printf("%s\n",CkImap_lastErrorText(imap));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        return;
    }

    // Connect to an IMAP server via the already established SSH tunnel.
    // Because the SSH tunnel has been previously setup,
    // this does not establish a direct connection with the IMAP
    // server.  It directs the SSH server to establish the connection.

    // In this example, the IMAP server requires SSL/TLS.  The TLS connection
    // will be enclosed within the SSH tunnel.
    CkImap_putSsl(imap,TRUE);
    CkImap_putPort(imap,993);
    success = CkImap_Connect(imap,"imap.my-imap-server.com");
    if (success == FALSE) {
        printf("%s\n",CkImap_lastErrorText(imap));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        return;
    }

    // Authenticate with the IMAP server via the SSH tunnel.
    success = CkImap_Login(imap,"myLogin","myPassword");
    if (success == FALSE) {
        printf("%s\n",CkImap_lastErrorText(imap));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        return;
    }

    // Select an IMAP mailbox
    success = CkImap_SelectMailbox(imap,"Inbox");
    if (success == FALSE) {
        printf("%s\n",CkImap_lastErrorText(imap));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        return;
    }

    // How many messages in Inbox?
    msgCount = CkImap_getNumMessages(imap);
    if (msgCount == 0) {
        printf("No messages found.\n");
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        return;
    }

    upperBound = 10;
    if (msgCount < upperBound) {
        upperBound = msgCount;
    }

    // Download up to the 1st 10 messages.
    email = CkEmail_Create();

    bUid = FALSE;
    for (i = 1; i <= upperBound; i++) {

        success = CkImap_FetchEmail(imap,FALSE,i,bUid,email);
        if (success == FALSE) {
            printf("%s\n",CkImap_lastErrorText(imap));
            CkSocket_Dispose(tunnel);
            CkImap_Dispose(imap);
            CkEmail_Dispose(email);
            return;
        }

        printf("%s\n",CkEmail_ck_from(email));
        printf("%s\n",CkEmail_subject(email));

    }

    // Disconnect from the IMAP server.
    // The SSH tunnel remains open.
    success = CkImap_Disconnect(imap);
    if (success == FALSE) {
        printf("%s\n",CkImap_lastErrorText(imap));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        CkEmail_Dispose(email);
        return;
    }

    // It is possible to re-use the existing SSH tunnel for the next connection:
    success = CkImap_Connect(imap,"imap.my-imap-server2.com");
    if (success == FALSE) {
        printf("%s\n",CkImap_lastErrorText(imap));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        CkEmail_Dispose(email);
        return;
    }

    // Review the LastErrorText to see that the connection was made via the SSH tunnel:
    printf("%s\n",CkImap_lastErrorText(imap));

    // This closes the SSH channel, which is the connection with the IMAP server.
    // It does not close the SSH tunnel
    success = CkImap_Disconnect(imap);
    if (success == FALSE) {
        printf("%s\n",CkImap_lastErrorText(imap));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        CkEmail_Dispose(email);
        return;
    }

    // Finally, close the SSH tunnel.

    // Note: If other objects are using the same SSH tunnel, the tunnel is not 
    // actually closed.  It is only closed when the last object using the tunnel closes it.

    // At this point, both the imap and tunnel objects have references to the internal
    // SSH tunnel.  We need to close each.

    // This call doesn't actually close the tunnel yet, because the tunnel object still
    // holds an internal reference.
    success = CkImap_SshCloseTunnel(imap);
    if (success == FALSE) {
        printf("%s\n",CkImap_lastErrorText(imap));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        CkEmail_Dispose(email);
        return;
    }

    // This actually closes the SSH tunnel because it's the last object using it.
    success = CkSocket_SshCloseTunnel(tunnel);
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(tunnel));
        CkSocket_Dispose(tunnel);
        CkImap_Dispose(imap);
        CkEmail_Dispose(email);
        return;
    }

    printf("IMAP pre-existing SSH tunnel example completed.\n");


    CkSocket_Dispose(tunnel);
    CkImap_Dispose(imap);
    CkEmail_Dispose(email);

    }