o [NSE] Added snmpWalk function to SNMP library and updated scripts to use it

[Patrik]

scripts/snmp-win32-users.nse

@@ -21,60 +21,16 @@ license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
 categories = {"default", "discovery", "safe"}
 dependencies = {"snmp-brute"}
 
--- Version 0.2
+-- Version 0.3
 -- Created 01/15/2010 - v0.1 - created by Patrik Karlsson <patrik@cqure.net>
 -- Revised 01/19/2010 - v0.2 - fixed loop that would occure if a mib did not exist
+-- Revised 04/11/2010 - v0.3 - moved snmp_walk to snmp library <patrik@cqure.net>
 
 require "shortport"
 require "snmp"
 
 portrule = shortport.portnumber(161, "udp", {"open", "open|filtered"})
 
---- Walks the MIB Tree
---
--- @param socket socket already connected to the server
--- @param base_oid string containing the base object ID to walk
--- @return table containing <code>oid</code> and <code>value</code>
-function snmp_walk( socket, base_oid )
-	
-	local catch = function() socket:close()	end
-	local try = nmap.new_try(catch)	
-
-	local snmp_table = {}
-	local oid = base_oid
-	
-	while ( true ) do
-		
-		local value, response, snmpdata, options, item = nil, nil, nil, {}, {}
-		options.reqId = 28428 -- unnecessary?
-		payload = snmp.encode( snmp.buildPacket( snmp.buildGetNextRequest(options, oid) ) )
-
-		try(socket:send(payload))
-		response = try( socket:receive_bytes(1) )
-	
-		snmpdata = snmp.fetchResponseValues( response )
-		
-		value = snmpdata[1][1]
-		oid  = snmpdata[1][2]
-		
-		if not oid:match( base_oid ) or base_oid == oid then
-			break
-		end
-		
-		item.oid = oid
-		item.value = value
-		
-		table.insert( snmp_table, item )
-		
-	end
-
-	socket:close()
-	snmp_table.baseoid = base_oid
-
-	return snmp_table
-	
-end
-
 --- Processes the table and creates the script output
 --
 -- @param tbl table containing <code>oid</code> and <code>value</code>
@@ -100,11 +56,18 @@ action = function(host, port)
 	local try = nmap.new_try(catch)	
 	local snmpoid = "1.3.6.1.4.1.77.1.2.25"
 	local users = {}
+	local status
 
 	socket:set_timeout(5000)
 	try(socket:connect(host.ip, port.number, "udp"))
 	
-	users = snmp_walk( socket, snmpoid )
+	status, users = snmp.snmpWalk( socket, snmpoid )
+	socket:close()
+
+	if( not(status) ) then
+		return
+	end
+	
 	users = process_answer( users )
 
 	if ( users == nil ) or ( #users == 0 ) then