Update to use new pysnmp

src/server_common/snmpWalker.py

@@ -1,17 +1,29 @@
-from pysnmp.hlapi import *
-from pysnmp.smi import builder, compiler, rfc1902, view
+import asyncio
 
+from pysnmp.hlapi.v1arch.asyncio import (
+    CommunityData,
+    ObjectIdentity,
+    ObjectType,
+    SnmpDispatcher,
+    UdpTransportTarget,
+    next_cmd,
+)
+from pysnmp.smi import builder, compiler, error, rfc1902, view
+
+# must import pysnmp_sync_adapter after pysnmp.hlapi to ensure correct v1 functions chosen
+# from pysnmp_sync_adapter import create_transport, next_cmd_sync
 from server_common.utilities import SEVERITY, print_and_log
 
 # Assemble MIB browser
-mibBuilder = builder.MibBuilder()
-mibViewController = view.MibViewController(mibBuilder)
+MIB_BUILDER = builder.MibBuilder()
+MIB_VIEW_CONTROLLER = view.MibViewController(MIB_BUILDER)
 
-# compiler.addMibCompiler(mibBuilder, sources=['https://mibs.pysnmp.com/asn1/@mib@'], destination='snmp/mibs')
+# compiler.addMibCompiler(mibBuilder, sources=['https://mibs.pysnmp.com/asn1/@mib@'],
+# destination='snmp/mibs')
 # The below code needs MIBS to have been downloaded in the below subfolder.
-compiler.addMibCompiler(mibBuilder, sources=["file://snmp/mibs"])
+compiler.addMibCompiler(MIB_BUILDER, sources=["file://snmp/mibs"])
 # Pre-load MIB modules we expect to work with
-mibBuilder.loadModules(
+MIB_BUILDER.load_modules(
     "SNMPv2-MIB", "SNMP-COMMUNITY-MIB", "DISMAN-EXPRESSION-MIB", "RFC1213-MIB", "IF-MIB"
 )
 
@@ -25,57 +37,61 @@
 ]
 
 
-def walk(host, oid, requestedMIBs=INTERESTING_MIBS):
+async def walk_async(
+    host: str, oid: str, requested_mibs: list[str] = INTERESTING_MIBS
+) -> dict[str, str]:
     mibmap = dict()
-    for errorIndication, errorStatus, errorIndex, varBinds in nextCmd(
-        SnmpEngine(),
-        CommunityData("public", mpModel=0),
-        UdpTransportTarget((host, 161), timeout=3, retries=0),
-        ContextData(),
-        ObjectType(ObjectIdentity(oid)),
-        lookupMib=False,
-        lexicographicMode=False,
-        lookupNames=True,
-        lookupValues=True,
-    ):
-        if errorIndication:
-            ## we need to look at later - currently will print forever for a moxa that is
-            ## not on the network. Maybe return status and let caller decide whether to print
-            # print_and_log(f"Error:: for {host}: {errorIndication}", severity=SEVERITY.MINOR)
-            break
-
-        elif errorStatus:
-            print_and_log(
-                "host %s: %s at %s"
-                % (
-                    host,
-                    errorStatus.prettyPrint(),
-                    errorIndex and varBinds[int(errorIndex) - 1][0] or "?",
-                ),
-                severity=SEVERITY.MAJOR,
+    current_oid = ObjectType(ObjectIdentity(oid))
+    with SnmpDispatcher() as snmp_dispatcher:
+        while True:
+            error_indication, error_status, error_index, var_binds = await next_cmd(
+                snmp_dispatcher,
+                CommunityData("public", mpModel=0),
+                await UdpTransportTarget.create((host, 161), timeout=5, retries=0),
+                current_oid,
+                lookupMib=False,
+                lexicographicMode=False,
+                lookupNames=True,
+                lookupValues=True,
             )
-            break
+            if error_indication:
+                ## we need to look at later - currently will print forever for a moxa that is
+                ## not on the network. Maybe return status and let caller decide whether to print
+                print_and_log(f"Error:: for {host}: {error_indication}", severity=SEVERITY.MINOR)
+                break
 
-        else:
-            # Run var-binds through MIB resolver
-            # You may want to catch and ignore resolution errors here
-            varBinds = [
-                rfc1902.ObjectType(rfc1902.ObjectIdentity(x[0]), x[1]).resolveWithMib(
-                    mibViewController
+            elif error_status:
+                print_and_log(
+                    "host {}: {} at {}".format(
+                        host,
+                        error_status,
+                        error_index and var_binds[int(error_index) - 1][0] or "?",
+                    ),
+                    severity=SEVERITY.MAJOR,
                 )
-                for x in varBinds
-            ]
-            for name, value in varBinds:
-                mib, exists, port = name.prettyPrint().partition(".")
-                if not exists:
-                    port = ""
-                # print(name.prettyPrint(), ' = ', value.prettyPrint())
-                if mib in requestedMIBs:
-                    mibmap[name.prettyPrint()] = value.prettyPrint()
-                    # print('MIB-->', mib, ' port-->', port, ' = ', value.prettyPrint())
-                    # print_and_log('MIB -->%s, port --> %s, = %s' % (mib, port, value))
+                break
 
+            else:
+                # Run var-binds through MIB resolver
+                # We get some `Excessive instance identifier sub-OIDs left at MibTableRow` errors
+                # which is what the error.SmiError ignore is all about
+                res_var_binds = []
+                for x in var_binds:
+                    try:
+                        y = rfc1902.ObjectType(rfc1902.ObjectIdentity(x[0]), x[1]).resolveWithMib(
+                            MIB_VIEW_CONTROLLER
+                        )
+                        res_var_binds.append((y[0], y[1]))
+                    except error.SmiError:
+                        pass
+                for name, value in res_var_binds:
+                    mib, exists, port = name.prettyPrint().partition(".")
+                    if mib in requested_mibs:
+                        mibmap[name.prettyPrint()] = value.prettyPrint()
+                current_oid = var_binds[0]
     return mibmap
 
 
-# walk('130.246.49.46', '1.3.6.1.2.1')
+# for example     walk('130.246.49.46', '1.3.6.1.2.1')
+def walk(host: str, oid: str, requested_mibs: list[str] = INTERESTING_MIBS) -> dict[str, str]:
+    return asyncio.run(walk_async(host, oid, requested_mibs))