Zig Requires Chilkat v11.0.0+

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. Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

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

    const tunnel = try chilkat.Socket.init();
    defer tunnel.deinit();

    const ssh_hostname = "sftp.example.com";
    const ssh_port = 22;

    // Connect to an SSH server and establish the SSH tunnel:
    tunnel.sshOpenTunnel(ssh_hostname, ssh_port) catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        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.
    tunnel.sshAuthenticatePw("mySshLogin", "mySshPassword") catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        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.

    const imap = try chilkat.Imap.init();
    defer imap.deinit();

    // Let the IMAP object also use the SSH tunnel
    imap.useSshTunnel(tunnel) catch {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        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.setSsl(true);
    imap.setPort(993);
    imap.connect("imap.my-imap-server.com") catch {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        return;
    };

    // Authenticate with the IMAP server via the SSH tunnel.
    imap.login("myLogin", "myPassword") catch {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        return;
    };

    // Select an IMAP mailbox
    imap.selectMailbox("Inbox") catch {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        return;
    };

    // How many messages in Inbox?
    const msg_count = imap.getNumMessages();
    if (msg_count == 0) {
        std.debug.print("No messages found.\n", .{});
        return;
    }

    var upper_bound: i32 = 10;
    if (msg_count < upper_bound) {
        upper_bound = msg_count;
    }

    // Download up to the 1st 10 messages.
    const email = try chilkat.Email.init();
    defer email.deinit();
    var i: i32 = 0;
    const b_uid = false;
    i = 1;
    while (i <= upper_bound) : (i += 1) {
        imap.fetchEmail(false, @as(u32, @intCast(i)), b_uid, email) catch {
            std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
            return;
        };

        std.debug.print("{s}\n", .{try email.getFrom(alloc)});
        std.debug.print("{s}\n", .{try email.getSubject(alloc)});
    }

    // Disconnect from the IMAP server.
    // The SSH tunnel remains open.
    imap.disconnect() catch {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        return;
    };

    // It is possible to re-use the existing SSH tunnel for the next connection:
    imap.connect("imap.my-imap-server2.com") catch {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        return;
    };

    // Review the LastErrorText to see that the connection was made via the SSH tunnel:
    std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});

    // This closes the SSH channel, which is the connection with the IMAP server.
    // It does not close the SSH tunnel
    imap.disconnect() catch {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        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.
    imap.sshCloseTunnel() catch {
        std.debug.print("{s}\n", .{try imap.getLastErrorText(alloc)});
        return;
    };

    // This actually closes the SSH tunnel because it's the last object using it.
    tunnel.sshCloseTunnel() catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("IMAP pre-existing SSH tunnel example completed.\n", .{});
}