added queue_trap() and send_queued_traps() methods to better support

threads sending traps

Author: jbize

examples/simple_agent_trap.py

@@ -236,7 +236,8 @@ def HupHandler(signum, frame):
 	# Since we didn't give simpleCounter, simpleCounter64 and simpleTimeTicks
 	# a real meaning in the SIMPLE-MIB, we can basically do with them whatever
 	# we want. Here, we just increase them, although in different manners.
-	simpleCounter32.update(simpleCounter32.value() + 2)
+# 	simpleCounter32.update(simpleCounter32.value() + 2)
+	simpleCounter32.update(simpleCounter32.value() + 1)
 	simpleCounter64.update(simpleCounter64.value() + 4294967294)
 	simpleTimeTicks.update(simpleTimeTicks.value() + 1)
 
@@ -247,10 +248,12 @@ def HupHandler(signum, frame):
 	# agent.check_and_process() is trigering when trap is send so to disable endless loop
 	# there is flag set to skip sending trap on next check
 	if sendTrap:
+		print('Sending trap with simpleCounter32.value: {:}'.format(simpleCounter32.value()))
 		trapOid = 'SNMPv2-MIB::sysDescr'
 		trapData = [
 			{ 'oid':'SNMPv2-MIB::sysDescr.0', 'val':'test state' },
-			{ 'oid':'SIMPLE-MIB::simpleCounter64.0', 'val':1234567890L },
+			{ 'oid':'SIMPLE-MIB::simpleCounter32.0', 'val':simpleCounter32.value() },
+# 			{ 'oid':'SIMPLE-MIB::simpleCounter64.0', 'val':simpleCounter64.value() },
 		]
 		agent.send_trap(
 			oid = trapOid,

netsnmpagent.py

@@ -5,7 +5,6 @@
 #
 # Main module
 #
-
 """ Allows to write net-snmp subagents in Python.
 
 The Python bindings that ship with net-snmp support client operations
@@ -17,16 +16,18 @@
 
 This module, by contrast, concentrates on wrapping the net-snmp C API
 for SNMP subagents in an easy manner. """
+# Helper function courtesy of Alec Thomas and taken from
+# http://stackoverflow.com/questions/36932/how-can-i-represent-an-enum-in-python
 
-import sys, os, re, inspect, ctypes, socket, struct
 from collections import defaultdict
+import sys, os, re, inspect, ctypes, socket, struct
+from threading import Lock
+
 from netsnmpapi import *
-import netsnmpvartypes
 from netsnmpvartypes import _VarType
+import netsnmpvartypes
 
 
-# Helper function courtesy of Alec Thomas and taken from
-# http://stackoverflow.com/questions/36932/how-can-i-represent-an-enum-in-python
 def enum(*sequential, **named):
 	enums = dict(zip(sequential, range(len(sequential))), **named)
 	try:
@@ -139,6 +140,10 @@ def __init__(self, **args):
 		if self.UseMIBFiles and self.MIBFiles is not None and type(self.MIBFiles) not in (list, tuple):
 			self.MIBFiles = (self.MIBFiles,)
 
+		# Support the queueing of traps to prevent duplicates sent from threads
+		self.queued_traps = []
+		self.trap_lock = Lock()
+
 		# Initialize status attribute -- until start() is called we will accept
 		# SNMP object registrations
 		self._status = netsnmpAgentStatus.REGISTRATION
@@ -924,6 +929,26 @@ def shutdown(self):
 		# one effectively has to rely on the OS to release resources.
 		# libnsa.shutdown_agent()
 
+	def queue_trap(self, *args, **kwargs):
+		'''This method queues a trap to be sent from the main thread loop.
+		In SNMP v5.7.3 (and likely others), many traps sent from threads in agentx
+		sub-agents are duplicated.  This method and send_queued_traps() support
+		queueing traps in non-main threads and actually sending them from the
+		main thread in the "check_and_process loop."
+		'''
+		with self.trap_lock:
+			self.queued_traps.append((args, kwargs))
+
+	def send_queued_traps(self):
+		'''This method must be called from the main thread loop and dequeues and 
+		send all queued traps.
+		'''
+		with self.trap_lock:
+			for arg_tuple in self.queued_traps:
+				(args, kwargs) = arg_tuple
+				self.send_trap(*args, **kwargs)
+			self.queued_traps.clear()
+
 	def send_trap(self, *args, **kwargs):
 		'''Send SNMP traps
 			To send simple trap: