init

README.md

@@ -0,0 +1,6 @@
+# practice-go-snmptrap
+
+## references
+
+- https://github.com/sleepinggenius2/gosmi/
+- https://github.com/gosnmp/gosnmp

config.go

@@ -0,0 +1,23 @@
+package main
+
+type MIB struct {
+	Directory   []string `yaml:"directory"`
+	LoadModules []string `yaml:"modules"`
+}
+
+type TrapServer struct {
+	Address string `yaml:"addr"`
+	Port    string `yaml:"port"`
+}
+
+type Trap struct {
+	Ident  string `yaml:"ident"`
+	Format string `yaml:"format"`
+}
+
+type Config struct {
+	MIB        *MIB        `yaml:"mib"`
+	TrapServer *TrapServer `yaml:"snmp"`
+	Trap       []*Trap     `yaml:"trap"`
+	Debug      bool        `yaml:"debug"`
+}

config.yaml.sample

@@ -0,0 +1,25 @@
+snmp:
+  addr: 0.0.0.0
+  port: 9162
+mib:
+  directory:
+    - "/var/lib/snmp/mibs/ietf/"
+  modules:
+    - SNMPv2-MIB
+    - IF-MIB
+#   - CISCO-CONFIG-MAN-MIB
+#   - CISCO-GENERAL-TRAPS
+#   - CISCO-SYSLOG-MIB
+debug: false
+trap:
+# - ident: .1.3.6.1.4.1.9.9.41.2.0.1
+#   format: '[{{ addr }}] {{ read "CISCO-SYSLOG-MIB::clogHistFacility" }} is msg:{{ read "CISCO-SYSLOG-MIB::clogHistMsgName" }} text:{{ read "CISCO-SYSLOG-MIB::clogHistMsgText" }}'
+  - ident: .1.3.6.1.6.3.1.1.5.1
+    format: '{{ addr }} is cold started'
+  - ident: .1.3.6.1.6.3.1.1.5.2
+    format: '{{ addr }} is warm started'
+  - ident: .1.3.6.1.6.3.1.1.5.3
+    format: '{{ addr }} {{ read "IF-MIB::ifDescr" }} is linkdown'
+  - ident: .1.3.6.1.6.3.1.1.5.4
+    format: '{{ addr }} {{ read "IF-MIB::ifDescr" }} is linkup'
+

go.mod

@@ -0,0 +1,11 @@
+module github.com/yseto/practice-go-snmptrap
+
+go 1.19
+
+require (
+	github.com/gosnmp/gosnmp v1.35.0
+	github.com/sleepinggenius2/gosmi v0.4.4
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require github.com/alecthomas/participle v0.4.1 // indirect

go.sum

@@ -0,0 +1,29 @@
+github.com/alecthomas/go-thrift v0.0.0-20170109061633-7914173639b2/go.mod h1:CxCgO+NdpMdi9SsTlGbc0W+/UNxO3I0AabOEJZ3w61w=
+github.com/alecthomas/kong v0.2.1/go.mod h1:+inYUSluD+p4L8KdviBSgzcqEjUQOfC5fQDRFuc36lI=
+github.com/alecthomas/participle v0.4.1 h1:P2PJWzwrSpuCWXKnzqvw0b0phSfH1kJo4p2HvLynVsI=
+github.com/alecthomas/participle v0.4.1/go.mod h1:T8u4bQOSMwrkTWOSyt8/jSFPEnRtd0FKFMjVfYBlqPs=
+github.com/alecthomas/repr v0.0.0-20181024024818-d37bc2a10ba1/go.mod h1:xTS7Pm1pD1mvyM075QCDSRqH6qRLXylzS24ZTpRiSzQ=
+github.com/alecthomas/repr v0.0.0-20210301060118-828286944d6a/go.mod h1:2kn6fqh/zIyPLmm3ugklbEi5hg5wS435eygvNfaDQL8=
+github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
+github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gosnmp/gosnmp v1.35.0 h1:EuWWNPxTCdAUx2/NbQcSa3WdNxjzpy4Phv57b4MWpJM=
+github.com/gosnmp/gosnmp v1.35.0/go.mod h1:2AvKZ3n9aEl5TJEo/fFmf/FGO4Nj4cVeEc5yuk88CYc=
+github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sleepinggenius2/gosmi v0.4.4 h1:xgu+Mt7CptuB10IPt3SVXBAA9tARToT4B9xGzjjxQX8=
+github.com/sleepinggenius2/gosmi v0.4.4/go.mod h1:l8OniPmd3bJzw0MXP2/qh7AhP/e+bTY2CNivIhsnDT0=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

smi.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/sleepinggenius2/gosmi"
+	"github.com/sleepinggenius2/gosmi/types"
+)
+
+type SMI struct {
+	Modules []string
+	Paths   []string
+}
+
+func (s *SMI) Init() error {
+	gosmi.Init()
+
+	for _, path := range s.Paths {
+		gosmi.AppendPath(path)
+	}
+	for i, module := range s.Modules {
+		moduleName, err := gosmi.LoadModule(module)
+		if err != nil {
+			return err
+		}
+		s.Modules[i] = moduleName
+	}
+	return nil
+}
+
+func (s *SMI) Close() {
+	gosmi.Exit()
+}
+
+type Node struct {
+	Readable string
+	Node     gosmi.SmiNode
+}
+
+func (s *SMI) FromOID(oid string) (*Node, error) {
+	var node gosmi.SmiNode
+	var err error
+	if (oid[0] >= '0' && oid[0] <= '9') || oid[0] == '.' {
+		node, err = gosmi.GetNodeByOID(types.OidMustFromString(oid))
+	} else {
+		node, err = gosmi.GetNode(oid)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	subtree := node.GetSubtree()
+
+	if len(subtree) != 1 {
+		return nil, fmt.Errorf("mismatch oid : %q, len : %d", oid, len(subtree))
+	}
+
+	if !subtree[0].Oid.ParentOf(types.OidMustFromString(oid)) {
+		return nil, fmt.Errorf("mismatch oid. : %q", oid)
+	}
+
+	// readable
+	readable := strings.Replace(
+		types.OidMustFromString(oid).String(),
+		subtree[0].RenderNumeric(),
+		subtree[0].RenderQualified(),
+		1,
+	)
+
+	return &Node{Readable: readable, Node: subtree[0]}, nil
+}

trap-send/main.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"log"
+
+	g "github.com/gosnmp/gosnmp"
+)
+
+func main() {
+	g.Default.Target = "127.0.0.1"
+	g.Default.Port = 9162
+	g.Default.Version = g.Version2c
+	g.Default.Community = "public"
+	// g.Default.Logger = g.NewLogger(log.New(os.Stdout, "", 0))
+	err := g.Default.Connect()
+	if err != nil {
+		log.Fatalf("Connect() err: %v", err)
+	}
+	defer g.Default.Conn.Close()
+
+	trap := g.SnmpTrap{
+		Variables: []g.SnmpPDU{
+			{Value: ".1.3.6.1.6.3.1.1.5.3", Name: ".1.3.6.1.6.3.1.1.4.1.0", Type: g.ObjectIdentifier},
+			{Value: 9, Name: ".1.3.6.1.2.1.2.2.1.1.9", Type: g.Integer},
+			{Value: []byte("dum0"), Name: ".1.3.6.1.2.1.2.2.1.2.9", Type: g.OctetString},
+			{Value: 6, Name: ".1.3.6.1.2.1.2.2.1.3.9", Type: g.Integer},
+			{Value: 2, Name: ".1.3.6.1.2.1.2.2.1.7.9", Type: g.Integer},
+			{Value: 2, Name: ".1.3.6.1.2.1.2.2.1.8.9", Type: g.Integer},
+			{Value: ".1.3.6.1.4.1.8072.3.2.10", Name: ".1.3.6.1.6.3.1.1.4.3.0", Type: g.ObjectIdentifier},
+		},
+	}
+	/*
+		trap := g.SnmpTrap{
+			Variables: []g.SnmpPDU{
+				//			{Name: ".1.3.6.1.6.3.1.1.4.1.0", Type: g.ObjectIdentifier, Value: ".1.3.6.1.6.3.1.1.5.1"},
+				{Name: ".1.3.6.1.6.3.1.1.4.1.0", Type: g.ObjectIdentifier, Value: ".1.3.6.1.6.3.1.1.5.2"},
+			},
+		}
+	*/
+
+	/*
+		trap := g.SnmpTrap{
+			Variables: []g.SnmpPDU{
+				{Value: ".1.3.6.1.4.1.9.9.43.2.0.1", Name: ".1.3.6.1.6.3.1.1.4.1.0", Type: g.ObjectIdentifier},
+				{Value: 1, Name: ".1.3.6.1.4.1.9.9.43.1.1.6.1.3.10", Type: g.Integer},
+				{Value: 2, Name: ".1.3.6.1.4.1.9.9.43.1.1.6.1.4.10", Type: g.Integer},
+				{Value: 3, Name: ".1.3.6.1.4.1.9.9.43.1.1.6.1.5.10", Type: g.Integer},
+			},
+		}
+	*/
+
+	/*
+		trap := g.SnmpTrap{
+			Variables: []g.SnmpPDU{
+				{Value: ".1.3.6.1.4.1.9.9.41.2.0.1", Name: ".1.3.6.1.6.3.1.1.4.1.0", Type: g.ObjectIdentifier},
+				{Value: []byte("DOT11"), Name: ".1.3.6.1.4.1.9.9.41.1.2.3.1.2.1414", Type: g.OctetString},
+				{Value: 5, Name: ".1.3.6.1.4.1.9.9.41.1.2.3.1.3.1414", Type: g.Integer},
+				{Value: []byte("MAXRETRIES"), Name: ".1.3.6.1.4.1.9.9.41.1.2.3.1.4.1414", Type: g.OctetString},
+				{Value: []byte("Packet to client e28c.c759.c887 reached max retries, removing the client"), Name: ".1.3.6.1.4.1.9.9.41.1.2.3.1.5.1414", Type: g.OctetString},
+				{Value: uint32(79758314), Name: ".1.3.6.1.4.1.9.9.41.1.2.3.1.6.1414", Type: g.TimeTicks},
+			},
+		}
+	*/
+
+	_, err = g.Default.SendTrap(trap)
+	if err != nil {
+		log.Fatalf("SendTrap() err: %v", err)
+	}
+}

trap.go

@@ -0,0 +1,150 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"strings"
+	"text/template"
+
+	g "github.com/gosnmp/gosnmp"
+	"github.com/sleepinggenius2/gosmi/types"
+	"gopkg.in/yaml.v3"
+)
+
+const SnmpTrapOIDPrefix = ".1.3.6.1.6.3.1.1.4.1"
+
+var mibParser SMI
+var c Config
+
+func main() {
+	defer func() {
+		mibParser.Close()
+	}()
+
+	// TODO args.
+	f, err := os.ReadFile("config.yaml")
+
+	err = yaml.Unmarshal(f, &c)
+	if err != nil {
+		log.Fatalf("error: %v", err)
+	}
+
+	mibParser.Modules = c.MIB.LoadModules
+	mibParser.Paths = c.MIB.Directory
+	mibParser.Init()
+
+	// template tests.
+	funcmap := template.FuncMap{
+		"read": func(key string) string {
+			return "dummy"
+		},
+		"addr": func() string {
+			return "dummy"
+		},
+	}
+
+	var tmpl = template.New("").Funcs(funcmap)
+
+	for i := range c.Trap {
+		if _, err := tmpl.Parse(c.Trap[i].Format); err != nil {
+			log.Fatalln(err)
+		}
+	}
+
+	trapListner := g.NewTrapListener()
+	trapListner.OnNewTrap = trapHandler
+	trapListner.Params = g.Default
+	if c.Debug {
+		trapListner.Params.Logger = g.NewLogger(log.New(os.Stdout, "<GOSNMP DEBUG LOGGER>", 0))
+	}
+
+	err = trapListner.Listen(net.JoinHostPort(c.TrapServer.Address, c.TrapServer.Port))
+	if err != nil {
+		log.Fatalf("error in listen: %s", err)
+	}
+}
+
+func trapHandler(packet *g.SnmpPacket, addr *net.UDPAddr) {
+	// log.Printf("got trapdata from %s\n", addr.IP)
+
+	var pad = make(map[string]string)
+	var specificTrapFormat string
+
+	for _, v := range packet.Variables {
+		if strings.HasPrefix(v.Name, SnmpTrapOIDPrefix) {
+			for i := range c.Trap {
+				if strings.HasPrefix(v.Value.(string), c.Trap[i].Ident) {
+					specificTrapFormat = c.Trap[i].Format
+				}
+			}
+		}
+
+		var padKey, padValue string
+		padKey = v.Name
+		node, err := mibParser.FromOID(v.Name)
+		if err != nil {
+			fmt.Printf("%+v\n", err)
+		} else {
+			if node != nil {
+				padKey = node.Node.RenderQualified()
+			}
+
+			if node.Node.Type != nil && node.Node.Type.BaseType == types.BaseTypeEnum {
+				i, ok := v.Value.(int)
+				if ok {
+					padValue = node.Node.Type.Enum.Name(int64(i))
+				}
+			}
+		}
+		if padValue == "" {
+			switch v.Type {
+			case g.OctetString:
+				b := v.Value.([]byte)
+				padValue = string(b)
+				// fmt.Printf("OID: %s, string: %s\n", v.Name, string(b))
+			case g.ObjectIdentifier:
+				valNode, err := mibParser.FromOID(v.Value.(string))
+				if err != nil {
+					fmt.Printf("%+v\n", err)
+					padValue = v.Value.(string)
+				} else {
+					padValue = valNode.Node.Name
+				}
+				// fmt.Printf("OID: %s, value: %s ObjectIdentifier: %s\n", v.Name, v.Value.(string), valNode.Node.Name)
+			default:
+				// fmt.Printf("trap: %+v\n", v)
+				padValue = fmt.Sprintf("%v", v.Value)
+			}
+		}
+
+		if padKey != "" && padValue != "" {
+			pad[padKey] = padValue
+		}
+	}
+
+	if specificTrapFormat == "" {
+		if c.Debug {
+			log.Printf("skip because nothing template : %+v\n", pad)
+		}
+		return
+	}
+
+	funcmap := template.FuncMap{
+		"read": func(key string) string {
+			return fmt.Sprintf("%s", pad[key])
+		},
+		"addr": func() string {
+			return addr.IP.String()
+		},
+	}
+
+	// fmt.Printf("%+v\n", pad)
+
+	var tpl = template.New("").Funcs(funcmap)
+
+	if err := template.Must(tpl.Parse(specificTrapFormat)).Execute(os.Stdout, pad); err != nil {
+		log.Println(err)
+	}
+}