Allow alternative agentx socket configuration

src/ax_interface/constants.py

@@ -1,6 +1,7 @@
 from enum import Enum, unique
 
 AGENTX_SOCKET_PATH = '/var/agentx/master'
+SNMPD_CONFIG_FILE = '/etc/snmp/snmpd.conf'
 
 # https://tools.ietf.org/html/rfc2741#section-6.1 -- PDU Header definition
 # Headers are fixed at 20 bytes.

src/ax_interface/socket_io.py

@@ -6,6 +6,7 @@
 """
 import asyncio
 import logging
+import re
 
 from . import logger, constants
 from .protocol import AgentX
@@ -25,6 +26,27 @@ def __init__(self, mib_table, run_event, loop):
 
         self.transport = self.ax_socket = None
 
+        self.ax_socket_path = constants.AGENTX_SOCKET_PATH
+
+        # The following code reads the snmp config file to see if the Agentx Socket path has been redefined
+        # from the default RFC value '/var/agentx/master'. We do not implement reading the SNMP daemon's
+        # command line to check if it has been redefined there, this should be an effort for the future
+        # perhaps via a psutil().cmdline() call
+
+        # open the snmpd config file and search for a agentx socket redefinition. Exceptions will be raised
+        # if the constants.SNMPD_CONFIG_FILE or the file in itself do not exist
+        pattern = re.compile("^agentxsocket\s+(.*)$", re.IGNORECASE)
+        try :
+            with open(constants.SNMPD_CONFIG_FILE,'rt') as config_file:
+                for line in config_file:
+                    match = pattern.search(line)
+                    if match:
+                        self.ax_socket_path = match.group(1)
+        except:
+            logger.warning("SNMPD config file not found, using default agentx file socket")
+
+        logger.info("Using agentx socket " + self.ax_socket_path)
+
     async def connection_loop(self):
         """
         Try/Retry connection coroutine to attach the socket.
@@ -37,10 +59,52 @@ async def connection_loop(self):
             try:
                 logger.info("Attempting AgentX socket bind...".format())
 
-                connection_routine = self.loop.create_unix_connection(
-                    protocol_factory=lambda: AgentX(self.mib_table, self.loop),
-                    path=constants.AGENTX_SOCKET_PATH,
-                    sock=self.ax_socket)
+                # Open the connection to the Agentx socket, we check the socket string to 
+                # either open a tcp socket or a Unix domain socket
+                if '/' in self.ax_socket_path:
+                    # This looks like a filesystem path so lets open it as a domain socket
+                    # but first lets remove 'unix' if it's in the spec
+                    if self.ax_socket_path.startswith('unix'):
+                        self.ax_socket_path = self.ax_socket_path.split(':')[1]
+                    connection_routine = self.loop.create_unix_connection(
+                        protocol_factory=lambda: AgentX(self.mib_table, self.loop),
+                        path=self.ax_socket_path,
+                        sock=self.ax_socket)
+                elif self.ax_socket_path.startswith('tcp'):
+                    # This looks like a tcp connection
+                    myhost = self.ax_socket_path.split(':')[1]
+                    myport = self.ax_socket_path.split(':')[2]
+                    connection_routine = self.loop.create_connection(
+                        protocol_factory=lambda: AgentX(self.mib_table, self.loop),
+                        host=myhost,
+                        port=myport,
+                        sock=self.ax_socket)
+                elif self.ax_socket_path.startswith('udp'):
+                    # This looks like a udp connection
+                    myhost = self.ax_socket_path.split(':')[1]
+                    myport = self.ax_socket_path.split(':')[2]
+                    connection_routine = self.loop.create_datagram_endpoint(
+                        protocol_factory=lambda: AgentX(self.mib_table, self.loop),
+                        host=myhost,
+                        port=myport,
+                        sock=self.ax_socket)
+                elif self.ax_socket_path.isdigit():
+                    # if the socket path is just a number then it is treated as a udp port on localhost
+                    myhost = 'localhost'
+                    myport = self.ax_socket_path
+                    connection_routine = self.loop.create_datagram_endpoint(
+                        protocol_factory=lambda: AgentX(self.mib_table, self.loop),
+                        host=myhost,
+                        port=myport,
+                        sock=self.ax_socket)
+                else:
+                    # We do not support 'ssh', 'dtlsudp', 'ipx', or 'aal5pvc' (ATM lol...) methods
+                    # default to the snmp default /var/agentx/master and log a warning
+                    logger.warning("Socket type " + self.ax_socket_path + " not supported, using default agentx file socket")
+                    connection_routine = self.loop.create_unix_connection(
+                        protocol_factory=lambda: AgentX(self.mib_table, self.loop),
+                        path=constants.AGENTX_SOCKET_PATH,
+                        sock=self.ax_socket)
 
                 # Initiate the socket connection
                 self.transport, protocol = await connection_routine