(PureBasic) POP3 over Multiple Hop SSH

Demonstrates how to read POP3 email (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => POP3Server

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkSsh.pb"
IncludeFile "CkEmail.pb"
IncludeFile "CkMailMan.pb"

Procedure ChilkatExample()

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

    ssh1.i = CkSsh::ckCreate()
    If ssh1.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Connect directly to the 1st SSH server.
    success.i = CkSsh::ckConnect(ssh1,"serverssh1.com",22)
    If success <> 1
        Debug CkSsh::ckLastErrorText(ssh1)
        CkSsh::ckDispose(ssh1)
        ProcedureReturn
    EndIf

    ; Authenticate using login/password:
    success = CkSsh::ckAuthenticatePw(ssh1,"ssh1Login","ssh1Password")
    If success <> 1
        Debug CkSsh::ckLastErrorText(ssh1)
        CkSsh::ckDispose(ssh1)
        ProcedureReturn
    EndIf

    ; Connect through the 1st SSH connection to reach a 2nd SSH server.
    ; Note: Any number of SSH connections may be simultaneously tunneled through a single
    ; existing SSH connection.
    ssh2.i = CkSsh::ckCreate()
    If ssh2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkSsh::ckConnectThroughSsh(ssh2,ssh1,"serverssh2.com",22)
    If success <> 1
        Debug CkSsh::ckLastErrorText(ssh2)
        CkSsh::ckDispose(ssh1)
        CkSsh::ckDispose(ssh2)
        ProcedureReturn
    EndIf

    ; Authenticate with ssh2...
    success = CkSsh::ckAuthenticatePw(ssh2,"ssh2Login","ssh2Password")
    If success <> 1
        Debug CkSsh::ckLastErrorText(ssh2)
        CkSsh::ckDispose(ssh1)
        CkSsh::ckDispose(ssh2)
        ProcedureReturn
    EndIf

    mailman.i = CkMailMan::ckCreate()
    If mailman.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Tell the mailman object to connect to the POP3 server though the ssh2 tunnel (which itself is routed through ssh1).
    ; The connection looks like this:  Application => ServerSSH1 => ServerSSH2 => POP3Server
    success = CkMailMan::ckUseSsh(mailman,ssh2)
    If success <> 1
        Debug CkMailMan::ckLastErrorText(mailman)
        CkSsh::ckDispose(ssh1)
        CkSsh::ckDispose(ssh2)
        CkMailMan::ckDispose(mailman)
        ProcedureReturn
    EndIf

    ; Set the POP3 server's hostname
    CkMailMan::setCkMailHost(mailman, "pop.someMailServer.com")

    ; Set the POP3 login/password.
    CkMailMan::setCkPopUsername(mailman, "myLogin")
    CkMailMan::setCkPopPassword(mailman, "myPassword")

    ; Establish the POP3 connection through the ssh2 tunnel.
    success = CkMailMan::ckPop3BeginSession(mailman)
    If success <> 1
        Debug CkMailMan::ckLastErrorText(mailman)
        CkSsh::ckDispose(ssh1)
        CkSsh::ckDispose(ssh2)
        CkMailMan::ckDispose(mailman)
        ProcedureReturn
    EndIf

    ; Get the number of messages in the mailbox.
    numMessages.i = CkMailMan::ckGetMailboxCount(mailman)

    i.i = 1

    email.i
    While i <= numMessages

        email = CkMailMan::ckFetchByMsgnum(mailman,i)
        If CkMailMan::ckLastMethodSuccess(mailman) <> 1
            Debug CkMailMan::ckLastErrorText(mailman)
            CkSsh::ckDispose(ssh1)
            CkSsh::ckDispose(ssh2)
            CkMailMan::ckDispose(mailman)
            ProcedureReturn
        EndIf

        Debug CkEmail::ckFrom(email) + ": " + CkEmail::ckSubject(email) + Chr(10)
        CkEmail::ckDispose(email)

        i = i + 1
    Wend

    ; Close the connection with the POP3 server.  (This closes the tunnel through ssh2)
    ; The connection with ssh2 is still alive, and may be used for more connections.
    success = CkMailMan::ckPop3EndSession(mailman)

    ; Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
    ; The connection with ssh1 is still alive, and may be used for more connections.

    CkSsh::ckDisconnect(ssh2)

    CkSsh::ckDisconnect(ssh1)


    CkSsh::ckDispose(ssh1)
    CkSsh::ckDispose(ssh2)
    CkMailMan::ckDispose(mailman)


    ProcedureReturn
EndProcedure