gosnmp

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// Copyright 2012 The GoSNMP Authors. All rights reserved.  Use of this
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// source code is governed by a BSD-style license that can be found in the
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// LICENSE file.
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/*
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Example usage and output:
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$ GOSNMP_TARGET=10.12.0.1 GOSNMP_PORT=161 go run main.go
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SEND INIT
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SENDING PACKET: gosnmp.SnmpPacket{Version:0x1, MsgFlags:0x0, SecurityModel:0x0, SecurityParameters:gosnmp.SnmpV3SecurityParameters(nil), ContextEngineID:"", ContextName:"", Community:"public", PDUType:0xa0, MsgID:0x0, RequestID:0x48ef671d, MsgMaxSize:0x0, Error:0x0, ErrorIndex:0x0, NonRepeaters:0x0, MaxRepetitions:0x0, Variables:[]gosnmp.SnmpPDU{gosnmp.SnmpPDU{Name:"1.3.6.1.2.1.1.4.0", Type:0x5, Value:interface {}(nil)}, gosnmp.SnmpPDU{Name:"1.3.6.1.2.1.1.7.0", Type:0x5, Value:interface {}(nil)}}, Logger:gosnmp.Logger(nil), SnmpTrap:gosnmp.SnmpTrap{Variables:[]gosnmp.SnmpPDU(nil), IsInform:false, Enterprise:"", AgentAddress:"", GenericTrap:0, SpecificTrap:0, Timestamp:0x0}}
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WAITING RESPONSE...
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2021/01/03 13:31:15 Query latency in seconds: 0.000625777
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GET RESPONSE OK: [48 63 2 1 1 4 6 112 117 98 108 105 99 162 50 2 4 72 239 103 29 2 1 0 2 1 0 48 36 48 19 6 8 43 6 1 2 1 1 4 0 4 7 99 111 110 116 97 99 116 48 13 6 8 43 6 1 2 1 1 7 0 2 1 78]
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Packet sanity verified, we got all the bytes (65)
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parseRawField: version
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Parsed version 1
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parseRawField: community
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Parsed community public
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UnmarshalPayload Meet PDUType 0xa2. Offset 13
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getResponseLength: 52
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parseRawField: request id
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requestID: 1223649053
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parseRawField: error-status
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errorStatus: 0
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parseRawField: error index
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error-index: 0
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vblLength: 38
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parseRawField: OID
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OID: .1.3.6.1.2.1.1.4.0
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decodeValue: msg: value
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decodeValue: type is OctetString
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decodeValue: value is []byte{0x63, 0x6f, 0x6e, 0x74, 0x61, 0x63, 0x74}
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parseRawField: OID
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OID: .1.3.6.1.2.1.1.7.0
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decodeValue: msg: value
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decodeValue: type is Integer
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decodeValue: value is 78
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0: oid: .1.3.6.1.2.1.1.4.0 string: contact
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1: oid: .1.3.6.1.2.1.1.7.0 number: 78
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*/
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package main
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import (
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	"fmt"
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	"log"
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	"os"
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	"strconv"
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	"time"
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	g "github.com/gosnmp/gosnmp"
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)
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func main() {
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	// get Target and Port from environment
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	envTarget := os.Getenv("GOSNMP_TARGET")
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	envPort := os.Getenv("GOSNMP_PORT")
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	if len(envTarget) <= 0 {
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		log.Fatalf("environment variable not set: GOSNMP_TARGET")
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	}
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	if len(envPort) <= 0 {
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		log.Fatalf("environment variable not set: GOSNMP_PORT")
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	}
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	port, _ := strconv.ParseUint(envPort, 10, 16)
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	// Build our own GoSNMP struct, rather than using g.Default.
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	// Do verbose logging of packets.
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	params := &g.GoSNMP{
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		Target:    envTarget,
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		Port:      uint16(port),
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		Community: "public",
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		Version:   g.Version2c,
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		Timeout:   time.Duration(2) * time.Second,
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		Logger:    g.NewLogger(log.New(os.Stdout, "", 0)),
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	}
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	err := params.Connect()
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	if err != nil {
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		log.Fatalf("Connect() err: %v", err)
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	}
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	defer params.Conn.Close()
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	// Function handles for collecting metrics on query latencies.
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	var sent time.Time
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	params.OnSent = func(x *g.GoSNMP) {
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		sent = time.Now()
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	}
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	params.OnRecv = func(x *g.GoSNMP) {
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		log.Println("Query latency in seconds:", time.Since(sent).Seconds())
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	}
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	oids := []string{"1.3.6.1.2.1.1.4.0", "1.3.6.1.2.1.1.7.0"}
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	result, err2 := params.Get(oids) // Get() accepts up to g.MAX_OIDS
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	if err2 != nil {
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		log.Fatalf("Get() err: %v", err2)
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	}
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	for i, variable := range result.Variables {
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		fmt.Printf("%d: oid: %s ", i, variable.Name)
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		// the Value of each variable returned by Get() implements
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		// interface{}. You could do a type switch...
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		switch variable.Type {
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		case g.OctetString:
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			fmt.Printf("string: %s\n", string(variable.Value.([]byte)))
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		default:
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			// ... or often you're just interested in numeric values.
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			// ToBigInt() will return the Value as a BigInt, for plugging
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			// into your calculations.
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			fmt.Printf("number: %d\n", g.ToBigInt(variable.Value))
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		}
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	}
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}
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