#!/usr/bin/env lua
-- SPDX-License-Identifier: GPL-2.0-or-later
--
-- Copyright (C) 2015 Red Hat, Inc.
--

-- Script for importing/converting OpenConnect VPN configuration files for NetworkManager
-- In general, the implementation follows the logic of import() from
-- https://git.gnome.org/browse/network-manager-openconnect/tree/properties/nm-openconnect.c

----------------------
-- Helper functions --
----------------------
function read_all(in_file)
  local f, msg = io.open(in_file, "r")
  if not f then return nil, msg; end
  local content = f:read("*all")
  f:close()
  return content
end

function uuid()
  math.randomseed(os.time())
  local template ='xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'
  local uuid = string.gsub(template, '[xy]', function (c)
    local v = (c == 'x') and math.random(0, 0xf) or math.random(8, 0xb)
    return string.format('%x', v)
  end)
  return uuid
end

function vpn_settings_to_text(vpn_settings)
  local t = {}
  for k,v in pairs(vpn_settings) do
    t[#t+1] = k.."="..v
  end
  return table.concat(t, "\n")
end

function usage()
  local basename = string.match(arg[0], '[^/\\]+$') or arg[0]
  print(basename .. " - convert/import OpenConnect VPN configuration to NetworkManager")
  print("Usage:")
  print("  " .. basename .. " <input-file> <output-file>")
  print("    - converts OpenConnect VPN config to NetworkManager keyfile")
  print("")
  print("  " .. basename .. " --import <input-file1> <input-file2> ...")
  print("    - imports OpenConnect VPN config(s) to NetworkManager")
  os.exit(1)
end


-------------------------------------------
-- Functions for VPN options translation --
-------------------------------------------
function handle_yes(t, option, value)
  t[option] = "yes"
end
function handle_generic(t, option, value)
  if not value[2] then io.stderr:write(string.format("Warning: ignoring invalid option '%s'\n", value[1])) end
  t[option] = value[2]
end

-- global variables
g_con_data = {}
g_vpn_data = {}

vpn2nm = {
  ["Description"]     = { nm_opt="id",                  func=handle_generic, tbl=g_con_data },
  ["Host"]            = { nm_opt="gateway",             func=handle_generic, tbl=g_vpn_data },
  ["CACert"]          = { nm_opt="cacert",              func=handle_generic, tbl=g_vpn_data },
  ["Proxy"]           = { nm_opt="proxy",               func=handle_generic, tbl=g_vpn_data },
  ["CSDEnable"]       = { nm_opt="enable_csd_trojan",   func=handle_yes,     tbl=g_vpn_data },
  ["CSDWrapper"]      = { nm_opt="csd_wrapper",         func=handle_generic, tbl=g_vpn_data },
  ["UserCertificate"] = { nm_opt="usercert",            func=handle_generic, tbl=g_vpn_data },
  ["PrivateKey"]      = { nm_opt="userkey",             func=handle_generic, tbl=g_vpn_data },
  ["FSID"]            = { nm_opt="pem_passphrase_fsid", func=handle_yes,     tbl=g_vpn_data },
  ["StokenSource"]    = { nm_opt="stoken_source",       func=handle_generic, tbl=g_vpn_data },
  ["StokenString"]    = { nm_opt="stoken_string",       func=handle_generic, tbl=g_vpn_data },
}

------------------------------------------------------
-- Read and convert the config into the global vars --
------------------------------------------------------
function read_and_convert(in_file)
  local function line_split(str)
    -- split at '=' character
    local sep, fields = "=", {}
    local pattern = string.format("([^%s]+)%s(.+)", sep, sep)
    fields[1], fields[2] = str:match(pattern)
    return fields
  end

  in_text, msg = read_all(in_file)
  if not in_text then return false, msg end

  -- loop through the config and convert it
  for line in in_text:gmatch("[^\r\n]+") do
    repeat
      -- skip comments and empty lines
      if line:find("^%s*[#;]") or line:find("^%s*$") then break end
      -- trim leading and trailing spaces
      line = line:find("^%s*$") and "" or line:match("^%s*(.*%S)")

      local words = line_split(line)
      local val = vpn2nm[words[1]]
      if val then
        if type(val) == "table" then val.func(val.tbl, val.nm_opt, words)
        else print(string.format("debug: '%s' : val=%s"..val)) end
      end
    until true
  end

  -- check mandatory parameters
  if not g_vpn_data["gateway"] then
    local msg = in_file .. ": Not a valid OpenConnect VPN configuration"
    return false, msg
  end
  return true
end

--------------------------------------------------------
-- Create and write connection file in keyfile format --
--------------------------------------------------------
function write_vpn_to_keyfile(in_file, out_file)
  connection = [[
[connection]
id=__NAME_PLACEHOLDER__
uuid=__UUID_PLACEHOLDER__
type=vpn
autoconnect=no

[ipv4]
method=auto
never-default=true

[ipv6]
method=auto

[vpn]
service-type=org.freedesktop.NetworkManager.openconnect
]]

  connection = connection .. vpn_settings_to_text(g_vpn_data)

  local con_name = g_con_data["id"] or (out_file:gsub(".*/", ""))
  connection = string.gsub(connection, "__NAME_PLACEHOLDER__", con_name)
  connection = string.gsub(connection, "__UUID_PLACEHOLDER__", uuid())

  -- write output file
  local f, err = io.open(out_file, "w")
  if not f then io.stderr:write(err) return false end
  f:write(connection)
  f:close()

  local ofname = out_file:gsub(".*/", "")
  io.stderr:write("Successfully converted VPN configuration: " .. in_file .. " => " .. out_file .. "\n")
  io.stderr:write("To use the connection, do:\n")
  io.stderr:write("# cp " .. out_file .. " /etc/NetworkManager/system-connections\n")
  io.stderr:write("# chmod 600 /etc/NetworkManager/system-connections/" .. ofname .. "\n")
  io.stderr:write("# nmcli con load /etc/NetworkManager/system-connections/" .. ofname .. "\n")
  return true
end

---------------------------------------------
-- Import VPN connection to NetworkManager --
---------------------------------------------
function import_vpn_to_NM(filename)
  local lgi = require 'lgi'
  local GLib = lgi.GLib
  local NM = lgi.NM

  -- function creating NMConnection
  local function create_profile(name)
    local profile = NM.SimpleConnection.new()

    s_con = NM.SettingConnection.new()
    s_vpn = NM.SettingVpn.new()
    s_con[NM.SETTING_CONNECTION_ID] = name
    s_con[NM.SETTING_CONNECTION_UUID] = uuid()
    s_con[NM.SETTING_CONNECTION_TYPE] = "vpn"
    s_vpn[NM.SETTING_VPN_SERVICE_TYPE] = "org.freedesktop.NetworkManager.openconnect"
    for k,v in pairs(g_vpn_data) do
      s_vpn:add_data_item(k, v)
    end

    profile:add_setting(s_con)
    profile:add_setting(s_vpn)
    return profile
  end

  -- callback function for add_connection()
  local function added_cb(client, result, data)
    local con,err,code = client:add_connection_finish(result)
    if con then
      print(string.format("%s: Imported to NetworkManager: %s - %s",
                          filename, con:get_uuid(), con:get_id()))
    else
      io.stderr:write(code .. ": " .. err .. "\n");
      return false
    end
    main_loop:quit()
  end

  local profile_name = g_con_data["id"] or string.match(filename, '[^/\\]+$') or filename
  main_loop = GLib.MainLoop(nil, false)
  local con = create_profile(profile_name)
  local client = NM.Client.new()

  -- send the connection to NetworkManager
  client:add_connection_async(con, true, nil, added_cb, nil)

  -- run main loop so that the callback could be called
  main_loop:run()
  return true
end


---------------------------
-- Main code starts here --
---------------------------
local import_mode = false
local infile, outfile

-- parse command-line arguments
if not arg[1] or arg[1] == "--help" or arg[1] == "-h" then usage() end
if arg[1] == "--import" or arg[1] == "-i" then
  infile = arg[2]
  if not infile then usage() end
  import_mode = true
else
  infile  = arg[1]
  outfile = arg[2]
  if not infile or not outfile then usage() end
  if arg[3] then usage() end
end

if import_mode then
  -- check if lgi is available
  local success,msg = pcall(require, 'lgi')
  if not success then
    io.stderr:write("Lua lgi module is not available, please install it (usually lua-lgi package)\n")
    -- print(msg)
    os.exit(1)
  end
  -- read configs, convert them and import to NM
  for i = 2, #arg do
    ok, err_msg = read_and_convert(arg[i])
    if ok then import_vpn_to_NM(arg[i])
    else io.stderr:write(err_msg .. "\n") end
    -- reset global vars
    g_con_data = {}
    g_vpn_data = {}
  end
else
  -- read configs, convert them and write as NM keyfile connection
  ok, err_msg = read_and_convert(infile)
  if ok then write_vpn_to_keyfile(infile, outfile)
  else io.stderr:write(err_msg .. "\n") end
end