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POproper getnext logic in a pass_persist handler
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copied!<p>I'm working on a small script that'll act as an snmp pass_persist handler. I want it to read a file in (called 'numbers', for now in the same dir) which just contains some integers and return these as an oid tree. </p> <p>I've been stuck on this for a few days now, and I realise now it's due to a <em>fundamental misunderstanding</em> of how snmpd works. I'm using the snmpd.conf man page which makes no mention of any difference in how 'get' and 'getnext' requests are to be handled, but I assume there is one. I can't for the life of me get snmpwalk to work with this script.</p> <p>Could someone who knows a little more about snmp look this code over ? I've seen several other versions of pass scripts, including a few in python but I've not been able to see from looking at the code how they handle the protocol differently to my code. I saw one implementation that handled a blank command ( '' ), but others that apparently didn't.</p> <p>Basically, I'm pretty confused at this point ! - It's also proving pretty hard to debug snmpd as it's the one calling my script, not me. I'm logging what i can, and running snmpd in the foreground, but other than that it's all a bit "black-box".</p> <p>Can anyone shed some light ?</p> <p>i.e: numbers file:</p> <pre> 101 102 103 I want returned as: .1.3.6.1.4.1..[snip]..1 = 101 .1.3.6.1.4.1..[snip]..2 = 102 .1.3.6.1.4.1..[snip]..3 = 103 </pre> <p>My script (I'm not worried about returning anything other than integers, and i know the file close will never be reached, but it makes me feel better):</p> <pre><code> #!/bin/python -u import os,sys, syslog def getLine(): return sys.stdin.readline().strip() def getFileLine(sub_oid, lines): sub_oid = int(sub_oid) if sub_oid >= len(lines): return 'NONE' else: return lines[sub_oid] def printOutput(oid, var_type, varbind_value): if varbind_value == 'NONE': print 'NONE' else: print oid print var_type print varbind_value ###################################################### sub_oid = 0 FH = open('numbers','r') lines = FH.readlines() while True: command = getLine() syslog.syslog("command: %s" % command) if command == 'PING': syslog.syslog('got a ping') print 'PONG' elif command == 'get': given_oid = getLine() sub_oid = int(given_oid.split('.')[-1]) varbind_value = getFileLine(sub_oid, lines) printOutput(given_oid, 'integer', varbind_value.strip()) elif command == 'getnext': given_oid = getLine() syslog.syslog("got a requested oid of: %s" % given_oid) sub_oid = int(given_oid.split('.')[-1]) varbind_value = getFileLine(sub_oid, lines) printOutput(given_oid, 'integer', varbind_value.strip()) else: syslog.syslog("Unknown command: %s" % command) FH.close() </code></pre>

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