Zig

SMTP over Multiple Hop SSH

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

Application => ServerSSH1 => ServerSSH2 => SmtpServer

The ConnectThroughSsh and UseSsh methods are added in Chilkat version 9.5.0.55 to accomplish this task.

Zig

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

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

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

    const ssh1 = try chilkat.Ssh.init();
    defer ssh1.deinit();

    // Connect directly to the 1st SSH server.
    ssh1.connect("serverssh1.com", 22) catch {
        std.debug.print("{s}\n", .{try ssh1.getLastErrorText(alloc)});
        return;
    };

    // Authenticate using login/password:
    ssh1.authenticatePw("ssh1Login", "ssh1Password") catch {
        std.debug.print("{s}\n", .{try ssh1.getLastErrorText(alloc)});
        return;
    };

    // 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.
    const ssh2 = try chilkat.Ssh.init();
    defer ssh2.deinit();
    ssh2.connectThroughSsh(ssh1, "serverssh2.com", 22) catch {
        std.debug.print("{s}\n", .{try ssh2.getLastErrorText(alloc)});
        return;
    };

    // Authenticate with ssh2...
    ssh2.authenticatePw("ssh2Login", "ssh2Password") catch {
        std.debug.print("{s}\n", .{try ssh2.getLastErrorText(alloc)});
        return;
    };

    const mailman = try chilkat.MailMan.init();
    defer mailman.deinit();

    // Tell the mailman object to connect to the SMTP server though the ssh2 tunnel (which itself is routed through ssh1).
    // The connection looks like this:  Application => ServerSSH1 => ServerSSH2 => SMTPServer
    mailman.useSsh(ssh2) catch {
        std.debug.print("{s}\n", .{try mailman.getLastErrorText(alloc)});
        return;
    };

    // Set the SMTP server.
    mailman.setSmtpHost("smtp.someserver.com");

    // Set the SMTP login/password (if required)
    mailman.setSmtpUsername("myUsername");
    mailman.setSmtpPassword("myPassword");

    // Create a new email object
    const email = try chilkat.Email.init();
    defer email.deinit();

    email.setSubject("This is a test");
    email.setBody("This is a test");
    email.setFrom("Chilkat Support <support@chilkatsoft.com>");
    try email.addTo("Chilkat Admin", "admin@chilkatsoft.com");

    mailman.sendEmail(email) catch {
        std.debug.print("{s}\n", .{try mailman.getLastErrorText(alloc)});
        return;
    };

    // Close the connection with the server.  This closes the tunnel through ssh2.
    mailman.closeSmtpConnection() catch {
        std.debug.print("Connection to SMTP server not closed cleanly.\n", .{});
    };

    std.debug.print("Mail Sent!\n", .{});

    // 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.
    ssh2.disconnect();

    ssh1.disconnect();
}