From 4a62bb0086ed0769159aa3450181dd980f1274db Mon Sep 17 00:00:00 2001
From: Holger Hans Peter Freyther <holger@moiji-mobile.com>
Date: Sun, 25 Feb 2018 21:17:30 +0000
Subject: [PATCH] ms: Add lua script support utilities

Add a JSON encoder and a small module to sent registration and
other events per unix datagram socket.

json.lua fetched using:
$ wget -O src/osmo_ms_driver/lua/json.lua \
https://raw.githubusercontent.com/rxi/json.lua/master/json.lua

Change-Id: I43ae84a944c7f33e41d5de0880d4aaab3378809b
---
 src/osmo_ms_driver/lua/json.lua       | 380 ++++++++++++++++++++++++++
 src/osmo_ms_driver/lua/ms_support.lua |  31 +++
 2 files changed, 411 insertions(+)
 create mode 100644 src/osmo_ms_driver/lua/json.lua
 create mode 100644 src/osmo_ms_driver/lua/ms_support.lua

diff --git a/src/osmo_ms_driver/lua/json.lua b/src/osmo_ms_driver/lua/json.lua
new file mode 100644
index 00000000..dda6193b
--- /dev/null
+++ b/src/osmo_ms_driver/lua/json.lua
@@ -0,0 +1,380 @@
+--
+-- json.lua
+--
+-- Copyright (c) 2015 rxi
+--
+-- This library is free software; you can redistribute it and/or modify it
+-- under the terms of the MIT license. See LICENSE for details.
+--
+
+local json = { _version = "0.1.0" }
+
+-------------------------------------------------------------------------------
+-- Encode
+-------------------------------------------------------------------------------
+
+local encode
+
+local escape_char_map = {
+  [ "\\" ] = "\\\\",
+  [ "\"" ] = "\\\"",
+  [ "\b" ] = "\\b",
+  [ "\f" ] = "\\f",
+  [ "\n" ] = "\\n",
+  [ "\r" ] = "\\r",
+  [ "\t" ] = "\\t",
+}
+
+local escape_char_map_inv = { [ "\\/" ] = "/" }
+for k, v in pairs(escape_char_map) do
+  escape_char_map_inv[v] = k
+end
+
+
+local function escape_char(c)
+  return escape_char_map[c] or string.format("\\u%04x", c:byte())
+end
+
+
+local function encode_nil(val)
+  return "null"
+end 
+
+
+local function encode_table(val, stack)
+  local res = {}
+  stack = stack or {}
+
+  -- Circular reference?
+  if stack[val] then error("circular reference") end
+
+  stack[val] = true
+
+  if val[1] ~= nil or next(val) == nil then
+    -- Treat as array -- check keys are valid and it is not sparse
+    local n = 0
+    for k in pairs(val) do
+      if type(k) ~= "number" then
+        error("invalid table: mixed or invalid key types")
+      end
+      n = n + 1
+    end
+    if n ~= #val then
+      error("invalid table: sparse array")
+    end
+    -- Encode
+    for i, v in ipairs(val) do
+      table.insert(res, encode(v, stack))
+    end
+    stack[val] = nil
+    return "[" .. table.concat(res, ",") .. "]"
+
+  else
+    -- Treat as an object
+    for k, v in pairs(val) do
+      if type(k) ~= "string" then
+        error("invalid table: mixed or invalid key types")
+      end
+      table.insert(res, encode(k, stack) .. ":" .. encode(v, stack))
+    end
+    stack[val] = nil
+    return "{" .. table.concat(res, ",") .. "}"
+  end
+end
+
+
+local function encode_string(val)
+  return '"' .. val:gsub('[%z\1-\31\\"]', escape_char) .. '"'
+end
+
+
+local function encode_number(val)
+  -- Check for NaN, -inf and inf
+  if val ~= val or val <= -math.huge or val >= math.huge then
+    error("unexpected number value '" .. tostring(val) .. "'")
+  end
+  return string.format("%.14g", val)
+end
+
+
+local type_func_map = {
+  [ "nil"     ] = encode_nil,
+  [ "table"   ] = encode_table,
+  [ "string"  ] = encode_string,
+  [ "number"  ] = encode_number,
+  [ "boolean" ] = tostring,
+}
+
+
+encode = function(val, stack)
+  local t = type(val)
+  local f = type_func_map[t]
+  if f then
+    return f(val, stack)
+  end
+  error("unexpected type '" .. t .. "'")
+end
+
+
+function json.encode(val)
+  return ( encode(val) )
+end
+
+
+-------------------------------------------------------------------------------
+-- Decode
+-------------------------------------------------------------------------------
+
+local parse
+
+local function create_set(...) 
+  local res = {}
+  for i = 1, select("#", ...) do
+    res[ select(i, ...) ] = true
+  end
+  return res
+end
+
+local space_chars   = create_set(" ", "\t", "\r", "\n")
+local delim_chars   = create_set(" ", "\t", "\r", "\n", "]", "}", ",")
+local escape_chars  = create_set("\\", "/", '"', "b", "f", "n", "r", "t", "u")
+local literals      = create_set("true", "false", "null")
+
+local literal_map = {
+  [ "true"  ] = true,
+  [ "false" ] = false,
+  [ "null"  ] = nil,
+}
+
+
+local function next_char(str, idx, set, negate)
+  for i = idx, #str do
+    if set[str:sub(i, i)] ~= negate then
+      return i
+    end
+  end
+  return #str + 1
+end
+
+
+local function decode_error(str, idx, msg)
+  local line_count = 1
+  local col_count = 1
+  for i = 1, idx - 1 do
+    col_count = col_count + 1
+    if str:sub(i, i) == "\n" then
+      line_count = line_count + 1
+      col_count = 1
+    end
+  end
+  error( string.format("%s at line %d col %d", msg, line_count, col_count) )
+end
+
+
+local function codepoint_to_utf8(n)
+  -- http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=iws-appendixa
+  local f = math.floor
+  if n <= 0x7f then
+    return string.char(n)
+  elseif n <= 0x7ff then
+    return string.char(f(n / 64) + 192, n % 64 + 128)
+  elseif n <= 0xffff then
+    return string.char(f(n / 4096) + 224, f(n % 4096 / 64) + 128, n % 64 + 128)
+  elseif n <= 0x10ffff then
+    return string.char(f(n / 262144) + 240, f(n % 262144 / 4096) + 128,
+                       f(n % 4096 / 64) + 128, n % 64 + 128)
+  end
+  error( string.format("invalid unicode codepoint '%x'", n) )
+end
+
+
+local function parse_unicode_escape(s)
+  local n1 = tonumber( s:sub(3, 6),  16 )
+  local n2 = tonumber( s:sub(9, 12), 16 )
+  -- Surrogate pair?
+  if n2 then
+    return codepoint_to_utf8((n1 - 0xd800) * 0x400 + (n2 - 0xdc00) + 0x10000)
+  else
+    return codepoint_to_utf8(n1)
+  end
+end
+
+
+local function parse_string(str, i)
+  local has_unicode_escape = false
+  local has_surrogate_escape = false
+  local has_escape = false
+  local last
+  for j = i + 1, #str do
+    local x = str:byte(j)
+
+    if x < 32 then
+      decode_error(str, j, "control character in string")
+    end
+
+    if last == 92 then -- "\\" (escape char)
+      if x == 117 then -- "u" (unicode escape sequence)
+        local hex = str:sub(j + 1, j + 5)
+        if not hex:find("%x%x%x%x") then
+          decode_error(str, j, "invalid unicode escape in string")
+        end
+        if hex:find("^[dD][89aAbB]") then
+          has_surrogate_escape = true
+        else
+          has_unicode_escape = true
+        end
+      else
+        local c = string.char(x)
+        if not escape_chars[c] then
+          decode_error(str, j, "invalid escape char '" .. c .. "' in string")
+        end
+        has_escape = true
+      end
+      last = nil
+
+    elseif x == 34 then -- '"' (end of string)
+      local s = str:sub(i + 1, j - 1)
+      if has_surrogate_escape then 
+        s = s:gsub("\\u[dD][89aAbB]..\\u....", parse_unicode_escape)
+      end
+      if has_unicode_escape then 
+        s = s:gsub("\\u....", parse_unicode_escape)
+      end
+      if has_escape then
+        s = s:gsub("\\.", escape_char_map_inv)
+      end
+      return s, j + 1
+    
+    else
+      last = x
+    end
+  end
+  decode_error(str, i, "expected closing quote for string")
+end
+
+
+local function parse_number(str, i)
+  local x = next_char(str, i, delim_chars)
+  local s = str:sub(i, x - 1)
+  local n = tonumber(s)
+  if not n then
+    decode_error(str, i, "invalid number '" .. s .. "'")
+  end
+  return n, x
+end
+
+
+local function parse_literal(str, i)
+  local x = next_char(str, i, delim_chars)
+  local word = str:sub(i, x - 1)
+  if not literals[word] then
+    decode_error(str, i, "invalid literal '" .. word .. "'")
+  end
+  return literal_map[word], x
+end
+
+
+local function parse_array(str, i)
+  local res = {}
+  local n = 1
+  i = i + 1
+  while 1 do
+    local x
+    i = next_char(str, i, space_chars, true)
+    -- Empty / end of array?
+    if str:sub(i, i) == "]" then 
+      i = i + 1
+      break
+    end
+    -- Read token
+    x, i = parse(str, i)
+    res[n] = x
+    n = n + 1
+    -- Next token 
+    i = next_char(str, i, space_chars, true)
+    local chr = str:sub(i, i)
+    i = i + 1
+    if chr == "]" then break end
+    if chr ~= "," then decode_error(str, i, "expected ']' or ','") end
+  end
+  return res, i
+end
+
+
+local function parse_object(str, i)
+  local res = {}
+  i = i + 1
+  while 1 do
+    local key, val
+    i = next_char(str, i, space_chars, true)
+    -- Empty / end of object?
+    if str:sub(i, i) == "}" then 
+      i = i + 1
+      break
+    end
+    -- Read key
+    if str:sub(i, i) ~= '"' then
+      decode_error(str, i, "expected string for key")
+    end
+    key, i = parse(str, i)
+    -- Read ':' delimiter
+    i = next_char(str, i, space_chars, true)
+    if str:sub(i, i) ~= ":" then
+      decode_error(str, i, "expected ':' after key")
+    end
+    i = next_char(str, i + 1, space_chars, true)
+    -- Read value
+    val, i = parse(str, i)
+    -- Set
+    res[key] = val
+    -- Next token
+    i = next_char(str, i, space_chars, true)
+    local chr = str:sub(i, i)
+    i = i + 1
+    if chr == "}" then break end
+    if chr ~= "," then decode_error(str, i, "expected '}' or ','") end
+  end
+  return res, i
+end
+
+
+local char_func_map = {
+  [ '"' ] = parse_string,
+  [ "0" ] = parse_number,
+  [ "1" ] = parse_number,
+  [ "2" ] = parse_number,
+  [ "3" ] = parse_number,
+  [ "4" ] = parse_number,
+  [ "5" ] = parse_number,
+  [ "6" ] = parse_number,
+  [ "7" ] = parse_number,
+  [ "8" ] = parse_number,
+  [ "9" ] = parse_number,
+  [ "-" ] = parse_number,
+  [ "t" ] = parse_literal,
+  [ "f" ] = parse_literal,
+  [ "n" ] = parse_literal,
+  [ "[" ] = parse_array,
+  [ "{" ] = parse_object,
+}
+
+
+parse = function(str, idx)
+  local chr = str:sub(idx, idx)
+  local f = char_func_map[chr]
+  if f then
+    return f(str, idx)
+  end
+  decode_error(str, idx, "unexpected character '" .. chr .. "'")
+end
+
+
+function json.decode(str)
+  if type(str) ~= "string" then
+    error("expected argument of type string, got " .. type(str))
+  end
+  return ( parse(str, next_char(str, 1, space_chars, true)) )
+end
+
+
+return json
diff --git a/src/osmo_ms_driver/lua/ms_support.lua b/src/osmo_ms_driver/lua/ms_support.lua
new file mode 100644
index 00000000..817a5649
--- /dev/null
+++ b/src/osmo_ms_driver/lua/ms_support.lua
@@ -0,0 +1,31 @@
+json = require("json")
+socket = require("socket")
+socket.unix = require("socket.unix")
+
+local g_c = socket.unix.dgram()
+local g_ms = nil
+
+local mod = {}
+
+-- Register the MS instance with the system
+function mod.register(ms, path)
+	g_ms = ms
+
+	g_c:connect(path)
+
+	local event = {}
+	event['ms'] = g_ms
+	event['type'] = 'register'
+	g_c:send(json.encode(event))
+end
+
+-- Send an event
+function mod.send(data)
+	local event = {}
+	event['ms'] = g_ms
+	event['type'] = 'event'
+	event['data'] = data
+	g_c:send(json.encode(event))
+end
+
+return mod