From 4ef792a06d60c4a8d63d8a04ae4d86269488b478 Mon Sep 17 00:00:00 2001
From: XeonSquared <redtailedairways@gmail.com>
Date: Fri, 20 Dec 2019 17:48:47 +1100
Subject: [PATCH] added an initial vtunnel implementation

---
 lib/interminitel.lua |  63 +++++++++++++++
 service/vtunnel.lua  | 177 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 240 insertions(+)
 create mode 100644 lib/interminitel.lua
 create mode 100644 service/vtunnel.lua

diff --git a/lib/interminitel.lua b/lib/interminitel.lua
new file mode 100644
index 0000000..7cc4f04
--- /dev/null
+++ b/lib/interminitel.lua
@@ -0,0 +1,63 @@
+local imt = {}
+
+imt.ttypes = {}
+imt.ttypes.string=1
+imt.ttypes.number=2
+
+imt.ftypes = {tostring,tonumber}
+
+function imt.to16bn(n)
+ return string.char(math.floor(n/256))..string.char(math.floor(n%256))
+end
+function imt.from16bn(s)
+ return (string.byte(s,1,1)*256)+string.byte(s,2,2)
+end
+
+function imt.encodePacket(...)
+ local tArgs = {...}
+ local packet = string.char(#tArgs%256)
+ for _,segment in ipairs(tArgs) do
+  local segtype = type(segment)
+  segment = tostring(segment)
+  packet = packet .. imt.to16bn(segment:len()) .. string.char(imt.ttypes[segtype]) .. tostring(segment)
+ end
+ packet = imt.to16bn(packet:len()) .. packet
+ return packet
+end
+
+function imt.decodePacket(s)
+ local function getfirst(n)
+  local ns = s:sub(1,n)
+  s=s:sub(n+1)
+  return ns
+ end
+ if s:len() < 2 then return false end
+ local plen = imt.from16bn(getfirst(2))
+ local segments = {}
+ if s:len() < plen then return false end
+ local nsegments = string.byte(getfirst(1))
+ --print(tostring(plen).." bytes, "..tostring(nsegments).." segments")
+ for i = 1, nsegments do
+  local seglen = imt.from16bn(getfirst(2))
+  local segtype = imt.ftypes[string.byte(getfirst(1))]
+  local segment = segtype(getfirst(seglen))
+  --print(seglen,segtype,segment,type(segment))
+  segments[#segments+1] = segment
+ end
+ return table.unpack(segments)
+end
+function imt.getRemainder(s)
+ local function getfirst(n)
+  local ns = s:sub(1,n)
+  s=s:sub(n+1)
+  return ns
+ end
+ local plen = imt.from16bn(getfirst(2))
+ if s:len() > plen then
+  getfirst(plen)
+  return s
+ end
+ return nil
+end
+
+return imt
diff --git a/service/vtunnel.lua b/service/vtunnel.lua
new file mode 100644
index 0000000..dda0f98
--- /dev/null
+++ b/service/vtunnel.lua
@@ -0,0 +1,177 @@
+local vcomponent = require "vcomponent"
+local serial = require "serialization"
+local component = require "component"
+local computer = require "computer"
+local event = require "event"
+local imt = require "interminitel"
+
+local cfg = {}
+cfg.peers = {}
+cfg.rtimer = 5
+cfg.katimer = 30
+local listeners = {}
+local timers = {}
+local proxies = {}
+
+local function loadcfg()
+ local f = io.open("/boot/cfg/vtunnel.cfg","rb")
+ if not f then return false end
+ for k,v in pairs(serial.unserialize(f:read("*a")) or {}) do
+  cfg[k] = v
+ end
+ f:close()
+end
+local function savecfg()
+ local f = io.open("/boot/cfg/vtunnel.cfg","wb")
+ if not f then 
+  print("Warning: unable to save configuration.")
+  return false
+ end
+ f:write(serial.serialize(cfg))
+ f:close()
+end
+
+local function createTunnel(host,port,addr,raddr)
+ local proxy = {address=addr,buffer=""}
+ function proxy.connect()
+  if proxy.socket then
+   proxy.socket.close()
+  end
+  proxy.socket = component.invoke(component.list("internet")(),"connect",host,port)
+  local st = computer.uptime()
+  repeat
+   coroutine.yield()
+  until proxy.socket.finishConnect() or computer.uptime() > st+5
+ end
+ function proxy.send(...)
+  rt = 0
+  while not proxy.socket.write(imt.encodePacket(...)) and rt < 10 do
+   proxy.connect()
+   rt = rt + 1
+  end
+  proxy.last = computer.uptime()
+ end
+ function proxy.read()
+  local rb, r
+  local rt = 0
+  while true do
+   rb,r = proxy.socket.read(4096)
+   if rb or rt > 10 then break end
+   if type(rb) == "nil" then
+    proxy.connect()
+   end
+   rt = rt + 1
+  end
+  proxy.buffer = proxy.buffer .. rb
+  while imt.decodePacket(proxy.buffer) do
+   computer.pushSignal("modem_message",addr,raddr,0,0,imt.decodePacket(proxy.buffer))
+   proxy.buffer = imt.getRemainder(proxy.buffer) or ""
+  end
+  if computer.uptime() > proxy.last + cfg.katimer then
+   proxy.socket.write("\0\1\0")
+   proxy.last = computer.uptime()
+  end
+ end
+ function proxy.getWakeMessage()
+  return false
+ end
+ proxy.setWakeMessage = proxy.getWakeMessage
+ function proxy.maxPacketSize()
+  return 8192
+ end
+ function proxy.getChannel()
+  return host..":"..tostring(port)
+ end
+ proxy.connect()
+ proxy.last = computer.uptime()
+ return proxy, read
+end
+
+vt = {}
+function start()
+ loadcfg()
+ for k,v in pairs(cfg.peers) do
+  print(string.format("Connecting to %s:%d",v.host,v.port))
+  v.addr = v.addr or vcomponent.uuid()
+  v.raddr = v.raddr or vcomponent.uuid()
+  local px,tr = createTunnel(v.host, v.port, v.addr, v.raddr)
+  vcomponent.register(v.addr, "tunnel", px)
+  timers[v.addr] = tr
+  proxies[v.addr] = px
+ end
+ for k,v in pairs(os.tasks()) do
+  if os.taskInfo(v).name:match("minitel") then
+   os.kill(v)
+  end
+ end
+end
+function vt.stop()
+ for k,v in pairs(listeners) do
+  event.ignore(v[1],v[2])
+ end
+ for k,v in pairs(timers) do
+  event.cancel(v)
+ end
+ for k,v in pairs(proxies) do
+  vcomponent.unregister(k)
+ end
+end
+
+function vt.listpeers()
+ for k,v in pairs(cfg.peers) do
+  print(string.format("#%d (%s:%d)\n Local address: %s\n Remote address: %s",k,v.host,v.port,v.addr,v.raddr))
+ end
+end
+function vt.addpeer(host,port)
+ port = tonumber(port) or 4096
+ local t = {}
+ t.host = host
+ t.port = port
+ t.addr = vcomponent.uuid()
+ t.raddr = vcomponent.uuid()
+ cfg.peers[#cfg.peers+1] = t
+ print(string.format("Added peer #%d (%s:%d) to the configuration.\nRestart to apply changes.",#cfg.peers,host,port))
+ savecfg()
+end
+function vt.delpeer(n)
+ n=tonumber(n)
+ if not n then
+  print("delpeer requires a number, representing the peer number, as an argument.")
+  return false
+ end
+ local dp = table.remove(cfg.peers, n)
+ savecfg()
+ print(string.format("Removed peer %s:%d",dp.host, dp.port))
+end
+
+function vt.settimer(time)
+ time = tonumber(time)
+ if not time then
+  print("Timer must be a number.")
+  return false
+ end
+ cfg.rtime = time
+ savecfg()
+end
+
+vt.start = start
+_G.libs.vtunnel = vt
+
+print(pcall(start))
+local last = computer.uptime()
+while true do
+ local tE = {coroutine.yield()}
+ if computer.uptime() > last + cfg.rtimer then
+  for k,v in pairs(timers) do
+   print(pcall(v))
+  end
+  last = computer.uptime()
+ end
+end
+
+--[[
+_G.vtunnel = {}
+
+_G.vtunnel.start = start
+_G.vtunnel.delpeer = delpeer
+]]