(Ruby) 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.

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

# Starting in v9.5.0.49, all Chilkat classes can be unlocked at once at the beginning of a program
# by calling UnlockBundle.  It requires a Bundle unlock code.
chilkatGlob = Chilkat::CkGlobal.new()
success = chilkatGlob.UnlockBundle("Anything for 30-day trial.")
if (success != true)
    print chilkatGlob.lastErrorText() + "\n";
    exit
end

tunnel = Chilkat::CkSocket.new()

sshHostname = "www.my-ssh-server.com"
sshPort = 22

# Connect to an SSH server and establish the SSH tunnel:
success = tunnel.SshOpenTunnel(sshHostname,sshPort)
if (success != true)
    print tunnel.lastErrorText() + "\n";
    exit
end

# 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 = tunnel.SshAuthenticatePw("mySshLogin","mySshPassword")
if (success != true)
    print tunnel.lastErrorText() + "\n";
    exit
end

# 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 = Chilkat::CkImap.new()

# Let the IMAP object also use the SSH tunnel
success = imap.UseSshTunnel(tunnel)
if (success != true)
    print imap.lastErrorText() + "\n";
    exit
end

# 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.
imap.put_Ssl(true)
imap.put_Port(993)
success = imap.Connect("imap.my-imap-server.com")
if (success != true)
    print imap.lastErrorText() + "\n";
    exit
end

# Authenticate with the IMAP server via the SSH tunnel.
success = imap.Login("myLogin","myPassword")
if (success != true)
    print imap.lastErrorText() + "\n";
    exit
end

# Select an IMAP mailbox
success = imap.SelectMailbox("Inbox")
if (success != true)
    print imap.lastErrorText() + "\n";
    exit
end

# How many messages in Inbox?
msgCount = imap.get_NumMessages()
if (msgCount == 0)
    print "No messages found." + "\n";
    exit
end

upperBound = 10
if (msgCount < upperBound)
    upperBound = msgCount
end

# Download up to the 1st 10 messages.

bUid = false
for i in 1 .. upperBound

    # email is a CkEmail
    email = imap.FetchSingle(i,bUid)
    if (imap.get_LastMethodSuccess() == false)
        print imap.lastErrorText() + "\n";
        exit

    else
        print email.ck_from() + "\n";
        print email.subject() + "\n";
        print "----" + "\n";

    end

end

# Disconnect from the IMAP server.
# The SSH tunnel remains open.
success = imap.Disconnect()
if (success != true)
    print imap.lastErrorText() + "\n";
    exit
end

# It is possible to re-use the existing SSH tunnel for the next connection:
success = imap.Connect("imap.my-imap-server2.com")
if (success != true)
    print imap.lastErrorText() + "\n";
    exit
end

# Review the LastErrorText to see that the connection was made via the SSH tunnel:
print imap.lastErrorText() + "\n";

# This closes the SSH channel, which is the connection with the IMAP server.
# It does not close the SSH tunnel
success = imap.Disconnect()
if (success != true)
    print imap.lastErrorText() + "\n";
    exit
end

# 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 = imap.SshCloseTunnel()
if (success != true)
    print imap.lastErrorText() + "\n";
    exit
end

# This actually closes the SSH tunnel because it's the last object using it.
success = tunnel.SshCloseTunnel()
if (success != true)
    print tunnel.lastErrorText() + "\n";
    exit
end

print "IMAP pre-existing SSH tunnel example completed." + "\n";