Tcl

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. Tcl

load ./chilkat.dll

set success 0

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

set tunnel [new_CkSocket]

set sshHostname "sftp.example.com"
set sshPort 22

# Connect to an SSH server and establish the SSH tunnel:
set success [CkSocket_SshOpenTunnel $tunnel $sshHostname $sshPort]
if {$success == 0} then {
    puts [CkSocket_lastErrorText $tunnel]
    delete_CkSocket $tunnel
    exit
}

# 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.
set success [CkSocket_SshAuthenticatePw $tunnel "mySshLogin" "mySshPassword"]
if {$success == 0} then {
    puts [CkSocket_lastErrorText $tunnel]
    delete_CkSocket $tunnel
    exit
}

# 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.

set imap [new_CkImap]

# Let the IMAP object also use the SSH tunnel
set success [CkImap_UseSshTunnel $imap $tunnel]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    exit
}

# 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_put_Ssl $imap 1
CkImap_put_Port $imap 993
set success [CkImap_Connect $imap "imap.my-imap-server.com"]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    exit
}

# Authenticate with the IMAP server via the SSH tunnel.
set success [CkImap_Login $imap "myLogin" "myPassword"]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    exit
}

# Select an IMAP mailbox
set success [CkImap_SelectMailbox $imap "Inbox"]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    exit
}

# How many messages in Inbox?
set msgCount [CkImap_get_NumMessages $imap]
if {$msgCount == 0} then {
    puts "No messages found."
    delete_CkSocket $tunnel
    delete_CkImap $imap
    exit
}

set upperBound 10
if {$msgCount < $upperBound} then {
    set upperBound $msgCount
}

# Download up to the 1st 10 messages.
set email [new_CkEmail]

set bUid 0
for {set i 1} {$i <= $upperBound} {incr i} {

    set success [CkImap_FetchEmail $imap 0 $i $bUid $email]
    if {$success == 0} then {
        puts [CkImap_lastErrorText $imap]
        delete_CkSocket $tunnel
        delete_CkImap $imap
        delete_CkEmail $email
        exit
    }

    puts [CkEmail_from $email]
    puts [CkEmail_subject $email]

}

# Disconnect from the IMAP server.
# The SSH tunnel remains open.
set success [CkImap_Disconnect $imap]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    delete_CkEmail $email
    exit
}

# It is possible to re-use the existing SSH tunnel for the next connection:
set success [CkImap_Connect $imap "imap.my-imap-server2.com"]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    delete_CkEmail $email
    exit
}

# Review the LastErrorText to see that the connection was made via the SSH tunnel:
puts [CkImap_lastErrorText $imap]

# This closes the SSH channel, which is the connection with the IMAP server.
# It does not close the SSH tunnel
set success [CkImap_Disconnect $imap]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    delete_CkEmail $email
    exit
}

# 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.
set success [CkImap_SshCloseTunnel $imap]
if {$success == 0} then {
    puts [CkImap_lastErrorText $imap]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    delete_CkEmail $email
    exit
}

# This actually closes the SSH tunnel because it's the last object using it.
set success [CkSocket_SshCloseTunnel $tunnel]
if {$success == 0} then {
    puts [CkSocket_lastErrorText $tunnel]
    delete_CkSocket $tunnel
    delete_CkImap $imap
    delete_CkEmail $email
    exit
}

puts "IMAP pre-existing SSH tunnel example completed."

delete_CkSocket $tunnel
delete_CkImap $imap
delete_CkEmail $email