LADX: Add Lua connector for BizHawk (#1579)

This is a Lua script for BizHawk that implements the relevant parts of
the RetroArch networking API used by the Archipelago LADX Client.

socket.lua and core.dll are exact copies of the same files in
data/lua/OOT and various other folders. There is a PR consolidating
these into the base folder, which this commit is anticipating.

LADX "just works"(tm) when this is loaded in Bizhawk.

data/lua/socket.lua

@@ -0,0 +1,132 @@
+-----------------------------------------------------------------------------
+-- LuaSocket helper module
+-- Author: Diego Nehab
+-- RCS ID: $Id: socket.lua,v 1.22 2005/11/22 08:33:29 diego Exp $
+-----------------------------------------------------------------------------
+
+-----------------------------------------------------------------------------
+-- Declare module and import dependencies
+-----------------------------------------------------------------------------
+local base = _G
+local string = require("string")
+local math = require("math")
+local socket = require("socket.core")
+module("socket")
+
+-----------------------------------------------------------------------------
+-- Exported auxiliar functions
+-----------------------------------------------------------------------------
+function connect(address, port, laddress, lport)
+    local sock, err = socket.tcp()
+    if not sock then return nil, err end
+    if laddress then
+        local res, err = sock:bind(laddress, lport, -1)
+        if not res then return nil, err end
+    end
+    local res, err = sock:connect(address, port)
+    if not res then return nil, err end
+    return sock
+end
+
+function bind(host, port, backlog)
+    local sock, err = socket.tcp()
+    if not sock then return nil, err end
+    sock:setoption("reuseaddr", true)
+    local res, err = sock:bind(host, port)
+    if not res then return nil, err end
+    res, err = sock:listen(backlog)
+    if not res then return nil, err end
+    return sock
+end
+
+try = newtry()
+
+function choose(table)
+    return function(name, opt1, opt2)
+        if base.type(name) ~= "string" then
+            name, opt1, opt2 = "default", name, opt1
+        end
+        local f = table[name or "nil"]
+        if not f then base.error("unknown key (".. base.tostring(name) ..")", 3)
+        else return f(opt1, opt2) end
+    end
+end
+
+-----------------------------------------------------------------------------
+-- Socket sources and sinks, conforming to LTN12
+-----------------------------------------------------------------------------
+-- create namespaces inside LuaSocket namespace
+sourcet = {}
+sinkt = {}
+
+BLOCKSIZE = 2048
+
+sinkt["close-when-done"] = function(sock)
+    return base.setmetatable({
+        getfd = function() return sock:getfd() end,
+        dirty = function() return sock:dirty() end
+    }, {
+        __call = function(self, chunk, err)
+            if not chunk then
+                sock:close()
+                return 1
+            else return sock:send(chunk) end
+        end
+    })
+end
+
+sinkt["keep-open"] = function(sock)
+    return base.setmetatable({
+        getfd = function() return sock:getfd() end,
+        dirty = function() return sock:dirty() end
+    }, {
+        __call = function(self, chunk, err)
+            if chunk then return sock:send(chunk)
+            else return 1 end
+        end
+    })
+end
+
+sinkt["default"] = sinkt["keep-open"]
+
+sink = choose(sinkt)
+
+sourcet["by-length"] = function(sock, length)
+    return base.setmetatable({
+        getfd = function() return sock:getfd() end,
+        dirty = function() return sock:dirty() end
+    }, {
+        __call = function()
+            if length <= 0 then return nil end
+            local size = math.min(socket.BLOCKSIZE, length)
+            local chunk, err = sock:receive(size)
+            if err then return nil, err end
+            length = length - string.len(chunk)
+            return chunk
+        end
+    })
+end
+
+sourcet["until-closed"] = function(sock)
+    local done
+    return base.setmetatable({
+        getfd = function() return sock:getfd() end,
+        dirty = function() return sock:dirty() end
+    }, {
+        __call = function()
+            if done then return nil end
+            local chunk, err, partial = sock:receive(socket.BLOCKSIZE)
+            if not err then return chunk
+            elseif err == "closed" then
+                sock:close()
+                done = 1
+                return partial
+            else return nil, err end
+        end
+    })
+end
+
+
+sourcet["default"] = sourcet["until-closed"]
+
+source = choose(sourcet)