Initial commit

sys/apis/socket.lua

@@ -0,0 +1,211 @@
+local Logger = require('logger')
+
+local socketClass = { }
+
+function socketClass:read(timeout)
+
+  if not self.connected then
+    Logger.log('socket', 'read: No connection')
+    return
+  end
+
+  local timerId
+  local filter
+
+  if timeout then
+    timerId = os.startTimer(timeout)
+  elseif self.keepAlive then
+    timerId = os.startTimer(3)
+  else
+    filter = 'modem_message'
+  end
+
+  while true do
+    local e, s, dport, dhost, msg, distance = os.pullEvent(filter)
+    if e == 'modem_message' and
+      dport == self.sport and dhost == self.shost and
+      msg then
+
+      if msg.type == 'DISC' then
+        -- received disconnect from other end
+        self.connected = false
+        self:close()
+        return
+      elseif msg.type == 'DATA' then
+        if msg.data then
+          if timerId then
+            os.cancelTimer(timerId)
+          end
+          return msg.data, distance
+        end
+      end
+    elseif e == 'timer' and s == timerId then
+      if timeout or not self.connected then
+        break
+      end
+      timerId = os.startTimer(3)
+    end
+  end
+end
+
+function socketClass:write(data)
+  if not self.connected then
+    Logger.log('socket', 'write: No connection')
+    return false
+  end
+  self.transmit(self.dport, self.dhost, {
+    type = 'DATA',
+    data = data,
+  })
+  return true
+end
+
+function socketClass:close()
+  if self.connected then
+    Logger.log('socket', 'closing socket ' .. self.sport)
+    self.transmit(self.dport, self.dhost, {
+      type = 'DISC',
+    })
+    self.connected = false
+  end
+  device.wireless_modem.close(self.sport)
+end
+
+-- write a ping every second (too much traffic!)
+local function pinger(socket)
+
+  local process = require('process')
+
+  socket.keepAlive = true
+
+  Logger.log('socket', 'keepAlive enabled')
+
+  process:newThread('socket_ping', function()
+    local timerId = os.startTimer(1)
+    local timeStamp = os.clock()
+
+    while true do
+      local e, id, dport, dhost, msg = os.pullEvent()
+
+      if e == 'modem_message' then
+        if dport == socket.sport and
+          dhost == socket.shost and
+          msg and
+          msg.type == 'PING' then
+
+          timeStamp = os.clock()
+        end
+      elseif e == 'timer' and id == timerId then
+        if os.clock() - timeStamp > 3 then
+          Logger.log('socket', 'Connection timed out')
+          socket:close()
+          break
+        end
+        timerId = os.startTimer(1)
+        socket.transmit(socket.dport, socket.dhost, {
+          type = 'PING',
+        })
+      end
+    end
+  end)
+end
+
+local Socket = { }
+
+local function loopback(port, sport, msg)
+  os.queueEvent('modem_message', 'loopback', port, sport, msg, 0)
+end
+
+local function newSocket(isLoopback)
+  for i = 16384, 32768 do
+    if not device.wireless_modem.isOpen(i) then
+      local socket = {
+        shost = os.getComputerID(),
+        sport = i,
+        transmit = device.wireless_modem.transmit,
+      }
+      setmetatable(socket, { __index = socketClass })
+
+      device.wireless_modem.open(socket.sport)
+
+      if isLoopback then
+        socket.transmit = loopback
+      end
+      return socket
+    end
+  end
+  error('No ports available')
+end
+
+function Socket.connect(host, port)
+
+  local socket = newSocket(host == os.getComputerID())
+  socket.dhost = host
+  Logger.log('socket', 'connecting to ' .. port)
+
+  socket.transmit(port, socket.sport, {
+    type = 'OPEN',
+    shost = socket.shost,
+    dhost = socket.dhost,
+  })
+
+  local timerId = os.startTimer(3)
+  repeat
+    local e, id, sport, dport, msg = os.pullEvent()
+    if e == 'modem_message' and
+       sport == socket.sport and
+       msg.dhost == socket.shost and
+       msg.type == 'CONN' then
+
+      socket.dport = dport
+      socket.connected = true
+      Logger.log('socket', 'connection established to %d %d->%d',
+                            host, socket.sport, socket.dport)
+
+      if msg.keepAlive then
+        pinger(socket)
+      end
+      os.cancelTimer(timerId)
+
+      return socket
+    end
+  until e == 'timer' and id == timerId
+
+  socket:close()
+end
+
+function Socket.server(port, keepAlive)
+
+  device.wireless_modem.open(port)
+  Logger.log('socket', 'Waiting for connections on port ' .. port)
+
+  while true do
+    local e, _, sport, dport, msg = os.pullEvent('modem_message')
+
+    if sport == port and
+       msg and
+       msg.dhost == os.getComputerID() and
+       msg.type == 'OPEN' then
+
+      local socket = newSocket(msg.shost == os.getComputerID())
+      socket.dport = dport
+      socket.dhost = msg.shost
+      socket.connected = true
+
+      socket.transmit(socket.dport, socket.sport, {
+        type = 'CONN',
+        dhost = socket.dhost,
+        shost = socket.shost,
+        keepAlive = keepAlive,
+      })
+      Logger.log('socket', 'Connection established %d->%d', socket.sport, socket.dport)
+
+      if keepAlive then
+        pinger(socket)
+      end
+      return socket
+    end
+  end
+end
+
+return Socket