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Continue SSH Tunnel Keyboard-Interactive Authentication

Demonstrates the Chilkat SshTunnel.ContinueKeyboardAuth method, which submits a response to a keyboard-interactive prompt. The only argument is the response text; for a request with multiple prompts, an XML response is supplied instead. It returns XML indicating the next prompt or the final result.

Background: This is the second half of the exchange started by StartKeyboardAuth. A server may issue several rounds of prompts, so a robust client loops: submit answers, read the returned XML, and continue until it sees success or failure. On success, BeginAccepting still must be called before the tunnel forwards traffic.

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

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

    // Demonstrates the SshTunnel.ContinueKeyboardAuth method, which submits a response to a
    // keyboard-interactive prompt.  The only argument is the response.  For multiple prompts, an XML
    // response is supplied instead.

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

    // The tunnel forwards accepted local connections to this destination through the SSH server.
    tunnel.setDestHostname("db.internal.example.com");
    tunnel.setDestPort(5432);

    // Connect to the SSH server.  This performs the TCP/proxy connection and SSH handshake, but
    // does not authenticate yet.
    const ssh_port = 22;
    tunnel.connect("ssh.example.com", ssh_port) catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        return;
    };

    // Begin keyboard-interactive authentication to receive the server's prompt(s).
    _ = tunnel.startKeyboardAuth(alloc, "mySshLogin") catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        return;
    };

    // Normally you would not hard-code the password in source.  You should instead obtain it
    // from an interactive prompt, environment variable, or a secrets vault.
    const password = "mySshPassword";

    // Submit the response (typically the password).  The returned XML indicates the next prompt or
    // the final result.
    const result = tunnel.continueKeyboardAuth(alloc, password) catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("{s}\n", .{result});

    const wait_for_thread_exit = true;
    tunnel.closeTunnel(wait_for_thread_exit) catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        return;
    };
}