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snmp.go
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snmp.go
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package main
import (
"fmt"
sc "strconv"
s "strings"
"time"
snmp "github.com/gosnmp/gosnmp"
nrgo "github.com/newrelic/go-agent/v3/newrelic"
log "github.com/sirupsen/logrus"
)
func SNMPSess(config Config) *snmp.GoSNMP {
var snmpCfg *snmp.GoSNMP
if config.Snmp.Version == "3" {
snmpCfg = &snmp.GoSNMP{
Target: config.Router.Hostname,
Port: config.Snmp.Port,
Version: snmp.Version3,
Timeout: time.Duration(config.Snmp.Timeout) * time.Second,
SecurityModel: snmp.UserSecurityModel, // TODO?
MsgFlags: snmp.AuthPriv, // TODO
SecurityParameters: &snmp.UsmSecurityParameters{
UserName: config.Snmp.V3.Username,
AuthenticationProtocol: snmp.SHA, // TODO
AuthenticationPassphrase: config.Snmp.V3.AuthPass,
PrivacyProtocol: snmp.AES, // TODO
PrivacyPassphrase: config.Snmp.V3.PrivPass,
},
}
} else {
log.Fatalf("Unsupported SNMP version '%s'", config.Snmp.Version)
}
err := snmpCfg.Connect()
if err != nil {
log.Fatalf("SNMP connect: %v", err)
}
return snmpCfg
}
func getPubIP(config Config, sess *snmp.GoSNMP) string {
var (
tx *nrgo.Transaction
seg *nrgo.Segment
)
pollSecondsErr := config.Router.IpPollSecondsErr
pubIfIndex := -1
if nrApp != nil {
tx = nrApp.StartTransaction("getPubIP")
defer tx.End()
// we'll do this every poll interval in case the router is a Juniper
// and it gets upgraded or is otherwise rebooted
seg = nrgo.StartSegment(tx, "BulkWalkAll ifDescr")
}
res, err := sess.BulkWalkAll(IF_DESCR)
if nrApp != nil {
seg.End()
}
if err != nil {
// non-fatal error; wait extra time before next poll
printAddLogEnt(fmt.Sprintf("BulkWalkAll %s ifDescr: %v", config.Router.Hostname, err), "Error", config.SlackWebHook)
if pollSecondsErr > 0 {
time.Sleep(time.Duration(pollSecondsErr) * time.Second)
return ""
}
}
if nrApp != nil {
seg = nrgo.StartSegment(tx, "find ifIndex of public interface")
}
for _, pdu := range res {
if pdu.Type == snmp.OctetString {
if string(pdu.Value.([]byte)) == config.Router.PubInterface {
lastDot := s.LastIndexByte(pdu.Name, '.')
if lastDot == -1 {
if nrApp != nil {
seg.End()
}
printAddLogEnt(fmt.Sprintf("%s: no dots in OID '%s'", config.Router.Hostname, pdu.Name), "Error", config.SlackWebHook)
if pollSecondsErr > 0 {
time.Sleep(time.Duration(pollSecondsErr) * time.Second)
return ""
}
}
pubIfIndex, err = sc.Atoi(pdu.Name[lastDot+1:])
break
}
}
}
if nrApp != nil {
seg.End()
}
if pubIfIndex == -1 {
printAddLogEnt(fmt.Sprintf("Could not find ifIndex for interface '%s'", config.Router.PubInterface), "Error", config.SlackWebHook)
return "N/A"
}
if nrApp != nil {
seg = nrgo.StartSegment(tx, "BulkWalkAll ipAdEntIfIndex")
}
res, err = sess.BulkWalkAll(IP_AD_ENT_IF_INDEX)
if nrApp != nil {
seg.End()
}
if err != nil {
errMsg := fmt.Sprintf("BulkWalkAll ipAdEntIfIndex: %v", err)
logBuf = append(logBuf, LogEnt{Message: errMsg, Level: "Error"})
logSlack(config.SlackWebHook)
log.Error(errMsg)
return "N/A"
}
if nrApp != nil {
seg = nrgo.StartSegment(tx, "find public IP")
}
for _, pdu := range res {
if pdu.Type == snmp.Integer && pdu.Value.(int) == pubIfIndex {
if nrApp != nil {
seg.End()
}
return pdu.Name[len(IP_AD_ENT_IF_INDEX)+1:]
}
}
if nrApp != nil {
seg.End()
}
return "N/A"
}