wip, and move PacketQueue

[hippotat.git] / hippotat / __init__.py

diff --git a/hippotat/__init__.py b/hippotat/__init__.py
index ee844cd53faa83b09602c3231043b2d9fb588861..c1ce08511aae7f43f9113512c1263ff7b54f5666 100644 (file)
--- a/hippotat/__init__.py
+++ b/hippotat/__init__.py
@@ -1,10 +1,13 @@
 # -*- python -*-
 
-import hippotat.slip as slip
+import twisted
+from twisted.internet import reactor
 
 import ipaddress
 from ipaddress import AddressValueError
 
+import hippotat.slip as slip
+
 #---------- packet parsing ----------
 
 def packet_addrs(packet):
@@ -38,3 +41,63 @@ def ipnetwork(input):
   except NetworkValueError:
     r = ipaddress.IPv6Network(input)
   return r
+
+#---------- ipif (SLIP) subprocess ----------
+
+class _IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol):
+  def __init__(self, router):
+    self._buffer = b''
+    self._router = router
+  def connectionMade(self): pass
+  def outReceived(self, data):
+    #print('RECV ', repr(data))
+    self._buffer += data
+    packets = slip.decode(self._buffer)
+    self._buffer = packets.pop()
+    for packet in packets:
+      if not len(packet): continue
+      (saddr, daddr) = packet_addrs(packet)
+      self._router(packet, saddr, daddr)
+  def processEnded(self, status):
+    status.raiseException()
+
+def start_ipif(command, router):
+  global ipif
+  ipif = _IpifProcessProtocol(router)
+  reactor.spawnProcess(ipif,
+                       '/bin/sh',['sh','-xc', command],
+                       childFDs={0:'w', 1:'r', 2:2})
+
+def queue_inbound(packet):
+  ipif.transport.write(slip.delimiter)
+  ipif.transport.write(slip.encode(packet))
+  ipif.transport.write(slip.delimiter)
+
+#---------- packet queue ----------
+
+class PacketQueue():
+  def __init__(self, max_queue_time):
+    self._max_queue_time = max_queue_time
+    self._pq = collections.deque() # packets
+
+  def append(self, packet):
+    self._pq.append((time.monotonic(), packet))
+
+  def nonempty(self):
+    while True:
+      try: (queuetime, packet) = self._pq[0]
+      except IndexError: return False
+
+      age = time.monotonic() - queuetime
+      if age > self.max_queue_time:
+        # strip old packets off the front
+        self._pq.popleft()
+        continue
+
+      return True
+
+  def popleft(self):
+    # caller must have checked nonempty
+    try: (dummy, packet) = self._pq[0]
+    except IndexError: return None
+    return packet