Lua

Socket Convert Existing TCP Connection to SSL/TLS

Demonstrates the Chilkat Socket ConvertToSsl method. Lua

local chilkat = require("chilkat")

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

local sock = chilkat.Socket.new()

-- --------------------------------------------------------------------
-- This example uses the public TCP/TLS echo service at https://tcpbin.com/
-- --------------------------------------------------------------------

-- The echo server at tcpbin.com expects to receive TCP connections on port 4242, and TLS connections on port 4243.
-- We could simply connect to port 4243 using TLS like this.
-- However, further below, this example shows how to initially make a TCP connection, and then convert the connection to TLS.
local useTls = true
local port = 4243
local maxWaitMs = 5000
local success = sock:connect("tcpbin.com", port, useTls, maxWaitMs)
if not success then
    print(sock.last_error_text)
    return
end

-- OK, we have a TLS connection.
-- Note: The server chooses the TLS protocol version.
-- We can see the version of the TLS connection that was established:
print("TLS version: " .. sock.tls_version)

sock:close(maxWaitMs)

-- ---------------------------------------------------------------------
-- Now we'll do the same, except first we connect to port 4243 using TCP,
-- and then convert the connection to TLS.
--
-- This may seem pointless, and it is for the case w/ this server.  However, there could be situations
-- where you're interacting with a server of some kind where there is a need to convert to/from TLS.
-- (This is common internal to many protocols, such as SMTP, IMAP, FTP, etc., and it is often called "explicit" SSL/TLS)

-- Connect again, except this time useTls is false, so we only have a simple TCP connection after this call.
useTls = false
success = sock:connect("tcpbin.com", port, useTls, maxWaitMs)
if not success then
    print(sock.last_error_text)
    return
end

-- Convert the existing TCP connection to TLS.
-- (The method name uses "SSL" because long ago, at the time of initial development, TLS 1.0 did not yet exist.)
success = sock:convert_to_ssl()
if not success then
    print(sock.last_error_text)
    return
end

-- OK, we now have a TLS connection.
-- Again, we can see the TLS version:
print("TLS version: " .. sock.tls_version)

sock:close(maxWaitMs)