Thursday, July 22, 2010
An update to a quick note on embedding languages within languages
In making this comment I came across this old post of mine from 2007 where I lament the amount of code required to query SNMP values in C. I took one look at the code I wanted:
OID sys = SNMPv2-MIB::sysObjectID.0;
if (sys == SNMPv2-SMI::enterprises.5567.1.1) /* riverstone */
{
IpAddress destination[] = IP-MIB::ip.24.4.1.1;
IpAddress mask[] = IP-MIB::ip.24.4.1.2;
IpAddress nexthop[] = IP-MIB::ip.24.4.1.4;
int protocol[] = IP-MIB::ip.24.4.1.7;
int age[] = IP-MIB::ip.24.4.1.8;
int metric[] = IP-MIB::ip.24.4.1.11;
int type[] = IP-MIB::ip.24.4.1.6;
}
else if (sys == SNMPv2-SMI::enterprises.9.1) /* cisco */
{
IpAddress destination[] = RFC1213-MIB::ipRouteDest;
IpAddress mask[] = RFC1213-MIB::ipRouteMask;
IpAddress nexthop[] = RFC1213-MIB::ipRouteNextHop;
int protocol[] = RFC1213-MIB::ipRouteProto;
int age[] = RFC1213-MIB::ipRouteAge;
int metric[] = RFC1213-MIB::ipRouteMetric1;
int type[] = RFC1213-MIB::ipRouteType;
}
for (i = 0 ; i < destination.length; i++)
{
print(
destination[i],
mask[i],
nexthop[i],
snmp.protocol(protocol[i]),
metric[i],
age[i]
);
}
and remembered—I did that!
Yup. Back in September of 2009 when I first started playing around with Lua. I installed the SNMP bindings for Lua and wrote the following:
#!/usr/local/bin/lua
-- http://luasnmp.luaforge.net/snmp.html
snmp = require "snmp"
OID = snmp.mib.oid
routeprotos =
{
"other ", "local ", "netmgmt ", "redirect ",
"egp ", "ggp ", "hello ", "rip ",
"is-is ", "es-is ", "igrp ", "bbnspf ",
"ospf ", "bgp "
}
print(" Dest Mask NextHop Proto Metric Age")
print("-------------------------------------------------------------------------------")
router = assert(snmp.open{
peer = arg[1] or "XXXXXXXXXXXXXXXXXXXXXXXXX" ,
community = arg[2] or "XXXXXXXXX"
})
cisco = OID "SNMPv2-SMI::enterprises.9.1"
riverstone = OID "SNMPv2-SMI::enterprises.5567.1.1"
sysid = router["SNMPv2-MIB::sysObjectID.0"]
if string.find(sysid,cisco,1,true) then
shouldbe = OID "RFC1213-MIB::ipRouteDest"
result =
{
{ oid = "RFC1213-MIB::ipRouteDest" } ,
{ oid = "RFC1213-MIB::ipRouteMask" } ,
{ oid = "RFC1213-MIB::ipRouteNextHop" } ,
{ oid = "RFC1213-MIB::ipRouteProto" } ,
{ oid = "RFC1213-MIB::ipRouteMetric1" } ,
{ oid = "RFC1213-MIB::ipRouteAge" } ,
}
elseif string.find(sysid,riverstone,1,true) then
shouldbe = OID "IP-MIB::ip.24.4.1.1"
result =
{
{ oid = "IP-MIB::ip.24.4.1.1" } ,
{ oid = "IP-MIB::ip.24.4.1.2" } ,
{ oid = "IP-MIB::ip.24.4.1.4" } ,
{ oid = "IP-MIB::ip.24.4.1.7" } ,
{ oid = "IP-MIB::ip.24.4.1.11" } ,
{ oid = "IP-MIB::ip.24.4.1.8" } ,
}
end
repeat
result,err = snmp.getnext(router,result);
if result ~= nil then
if string.find(result[1].oid,shouldbe,1,true) == nil then break end
print(string.format("%-16s",result[1].value)
.. string.format("%-16s",result[2].value)
.. string.format("%-16s",result[3].value)
.. routeprotos[result[4].value]
.. string.format("%-6d",result[5].value)
.. string.format("%-6d",result[6].value)
)
end
until false
os.exit(0)
