Lua Requires Chilkat v11.0.0+

WebSocket through SSH Tunnel

See more WebSocket Examples

This example shows how to establish a WebSocket connection through an SSH tunnel. The WebSocket protocol communications will be encapsulated within an SSH tunnel. Lua

local chilkat = require("chilkat")

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

-- --------------------------------------------------
-- This example borrows the code from the REST through SSH Tunnel example.
-- We first use the Chilkat Socket object to establish a connection to the WebSocket server through an SSH Tunnel.
-- Next, the Rest object uses the Socket object for its connection.
-- Finally, the WebSocket object uses the Rest object for its connection.
--
-- Hopefully the flexibility of this architecture is easy to see.  All of the HTTP functionality of the Rest object,
-- such as HTTP authentication, custom headers, etc. is available to the WebSocket.  Likewise, all of the advanced functionality
-- of the Socket object is in turn available to the Rest object.

-- The high-level steps for accomplishing the task of running the WebSocket protocol through an SSH accomplished as follows:
-- 1) Create the SSH tunnel using Chilkat Socket.
-- 2) Open a port-forwarding channel (to the WebSocket server) within the tunnel.
-- 2) Tell Rest to use the Socket object.
-- 3) Tell WebSocket to use the Rest object.

local tunnel = chilkat.Socket.new()

local sshHostname = "sftp.example.com"
local sshPort = 22

-- Connect to an SSH server and establish the SSH tunnel:
local success = tunnel:ssh_open_tunnel(sshHostname, sshPort)
if not success then
    print(tunnel.last_error_text)
    return
end

-- Authenticate with the SSH server via a login/password
-- or with a public key.
-- This example demonstrates SSH password authentication.
success = tunnel:ssh_authenticate_pw("mySshLogin", "mySshPassword")
if not success then
    print(tunnel.last_error_text)
    return
end

--  OK, the SSH tunnel is setup.  Now open a channel within the tunnel.

local bTls = true
local port = 443
local maxWaitMs = 5000

-- This returns a socket object that is a single channel within the SSH tunnel.
-- The SSH channel is our logical port-forwarded connection through the SSH tunnel.
-- Note: This example establishes a TLS connection to the target WebSocket server.
-- (The TLS protocol will run on the logical channel within the SSH tunnel.)
-- Your application can just as easily make a non-TLS connection by changing the arguments
-- passed to SshNewChannel.
local channel = chilkat.Socket.new()
success = tunnel:ssh_new_channel("some-websocket-server.com", port, bTls, maxWaitMs, channel)
if not success then
    print(tunnel.last_error_text)
    return
end

-- Create a REST object and tell it to use the SSH channel.
-- This connection is a TLS running on an SSH channel through an SSH tunnel.
-- In other words, TLS is wrapped within the SSH tunnel.
local rest = chilkat.Rest.new()
success = rest:use_connection(channel, false)
if not success then
    print(rest.last_error_text)
    return
end

-- Finally, tell our WebSocket object to use the Rest object..
local ws = chilkat.WebSocket.new()

-- Tell the WebSocket to use this connection.
success = ws:use_connection(rest)
if not success then
    print(ws.last_error_text)
    return
end

-- Add the standard WebSocket open handshake headers that will be needed.
-- (This adds the required HTTP request headers to the rest object.)
ws:add_client_headers()

-- Add any additional headers that might be desired.
-- Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
rest:add_header("Sec-WebSocket-Protocol", "x-some-websocket-subprotocol")
rest:add_header("Origin", "http://some-websocket-server.com")

-- Do the open handshake.
local responseBody = rest:full_request_no_body("GET", "/something")
if not rest.last_method_success then
    print(rest.last_error_text)
    return
end

-- If successful, the HTTP response status code should be 101,
-- and the response body will be empty. (If it failed, we'll have a look
-- at the response body..)
local statusCode = rest.response_status_code
print("Response status code: " .. statusCode)

if statusCode ~= 101 then
    print(responseBody)
    print("-- Failed because of unexpected response status code.")
    return
end

-- We have the expected 101 response, so let's now validate the
-- contents of the response, such as the value sent by the server in the
-- Sec-WebSocket-Accept header.
success = ws:validate_server_handshake()
if not success then
    print(ws.last_error_text)
    return
end

print("WebSocket connection successful.")

-- The application may now begin sending and receiving frames on the WebSocket connection.
-- (At this point, we're done with the rest object...)