Objective-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. Objective-C

#import <CkoSocket.h>
#import <NSString.h>
#import <CkoImap.h>
#import <CkoEmail.h>

BOOL success = NO;

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

CkoSocket *tunnel = [[CkoSocket alloc] init];

NSString *sshHostname = @"sftp.example.com";
int sshPort = 22;

//  Connect to an SSH server and establish the SSH tunnel:
success = [tunnel SshOpenTunnel: sshHostname sshPort: [NSNumber numberWithInt: sshPort]];
if (success == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    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 = [tunnel SshAuthenticatePw: @"mySshLogin" sshPassword: @"mySshPassword"];
if (success == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    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.

CkoImap *imap = [[CkoImap alloc] init];

//  Let the IMAP object also use the SSH tunnel
success = [imap UseSshTunnel: tunnel];
if (success == NO) {
    NSLog(@"%@",imap.LastErrorText);
    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.
imap.Ssl = YES;
imap.Port = [NSNumber numberWithInt:993];
success = [imap Connect: @"imap.my-imap-server.com"];
if (success == NO) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  Authenticate with the IMAP server via the SSH tunnel.
success = [imap Login: @"myLogin" password: @"myPassword"];
if (success == NO) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  Select an IMAP mailbox
success = [imap SelectMailbox: @"Inbox"];
if (success == NO) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  How many messages in Inbox?
int msgCount = [imap.NumMessages intValue];
if (msgCount == 0) {
    NSLog(@"%@",@"No messages found.");
    return;
}

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

//  Download up to the 1st 10 messages.
CkoEmail *email = [[CkoEmail alloc] init];
int i;
BOOL bUid = NO;
for (i = 1; i <= upperBound; i++) {

    success = [imap FetchEmail: NO msgId: i bUid: bUid email: email];
    if (success == NO) {
        NSLog(@"%@",imap.LastErrorText);
        return;
    }

    NSLog(@"%@",email.From);
    NSLog(@"%@",email.Subject);

}

//  Disconnect from the IMAP server.
//  The SSH tunnel remains open.
success = [imap Disconnect];
if (success == NO) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  It is possible to re-use the existing SSH tunnel for the next connection:
success = [imap Connect: @"imap.my-imap-server2.com"];
if (success == NO) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  Review the LastErrorText to see that the connection was made via the SSH tunnel:
NSLog(@"%@",imap.LastErrorText);

//  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 == NO) {
    NSLog(@"%@",imap.LastErrorText);
    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 = [imap SshCloseTunnel];
if (success == NO) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  This actually closes the SSH tunnel because it's the last object using it.
success = [tunnel SshCloseTunnel];
if (success == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    return;
}

NSLog(@"%@",@"IMAP pre-existing SSH tunnel example completed.");