add snmpv3 support

go.mod

@@ -4,4 +4,7 @@ go 1.24.4
 
 require github.com/google/gopacket v1.1.19
 
-require golang.org/x/sys v0.0.0-20190412213103-97732733099d // indirect
+require (
+	github.com/gosnmp/gosnmp v1.42.1 // indirect
+	golang.org/x/sys v0.13.0 // indirect
+)

go.sum

@@ -1,5 +1,7 @@
 github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
 github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
+github.com/gosnmp/gosnmp v1.42.1 h1:MEJxhpC5v1coL3tFRix08PYmky9nyb1TLRRgJAmXm8A=
+github.com/gosnmp/gosnmp v1.42.1/go.mod h1:CxVS6bXqmWZlafUj9pZUnQX5e4fAltqPcijxWpCitDo=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
@@ -7,10 +9,13 @@ golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzB
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859 h1:R/3boaszxrf1GEUWTVDzSKVwLmSJpwZ1yqXm8j0v2QI=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.15.0 h1:ugBLEUaxABaB5AJqW9enI0ACdci2RUd4eP51NTBvuJ8=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
+golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

snmp.go

@@ -0,0 +1,289 @@
+package tendrils
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+	"time"
+
+	"github.com/gosnmp/gosnmp"
+)
+
+type snmpConfig struct {
+	username   string
+	authKey    string
+	privKey    string
+	authProto  gosnmp.SnmpV3AuthProtocol
+	privProto  gosnmp.SnmpV3PrivProtocol
+	secLevel   gosnmp.SnmpV3MsgFlags
+	timeout    time.Duration
+	retries    int
+}
+
+func defaultSNMPConfig() *snmpConfig {
+	return &snmpConfig{
+		username:  "tendrils",
+		authKey:   "tendrils",
+		privKey:   "tendrils",
+		authProto: gosnmp.SHA512,
+		privProto: gosnmp.AES,
+		secLevel:  gosnmp.AuthPriv,
+		timeout:   5 * time.Second,
+		retries:   1,
+	}
+}
+
+func (t *Tendrils) connectSNMP(ip net.IP) (*gosnmp.GoSNMP, error) {
+	cfg := defaultSNMPConfig()
+
+	snmp := &gosnmp.GoSNMP{
+		Target:        ip.String(),
+		Port:          161,
+		Version:       gosnmp.Version3,
+		Timeout:       cfg.timeout,
+		Retries:       cfg.retries,
+		SecurityModel: gosnmp.UserSecurityModel,
+		MsgFlags:      cfg.secLevel,
+		SecurityParameters: &gosnmp.UsmSecurityParameters{
+			UserName:                 cfg.username,
+			AuthenticationProtocol:   cfg.authProto,
+			AuthenticationPassphrase: cfg.authKey,
+			PrivacyProtocol:          cfg.privProto,
+			PrivacyPassphrase:        cfg.privKey,
+		},
+	}
+
+	err := snmp.Connect()
+	if err != nil {
+		return nil, err
+	}
+
+	return snmp, nil
+}
+
+func (t *Tendrils) pollSNMP(ctx context.Context) {
+	ticker := time.NewTicker(5 * time.Minute)
+	defer ticker.Stop()
+
+	t.querySwitches()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			t.querySwitches()
+		}
+	}
+}
+
+func (t *Tendrils) querySwitches() {
+	nodes := t.nodes.All()
+
+	for _, node := range nodes {
+		for _, ip := range node.IPs {
+			if ip.To4() == nil {
+				continue
+			}
+
+			go t.querySNMPDevice(ip)
+		}
+	}
+}
+
+func (t *Tendrils) querySNMPDevice(ip net.IP) {
+	snmp, err := t.connectSNMP(ip)
+	if err != nil {
+		return
+	}
+	defer snmp.Conn.Close()
+
+	t.queryBridgeMIB(snmp, ip)
+	t.queryARPTable(snmp, ip)
+}
+
+func (t *Tendrils) queryBridgeMIB(snmp *gosnmp.GoSNMP, deviceIP net.IP) {
+	macOID := "1.3.6.1.2.1.17.4.3.1.1"
+	portOID := "1.3.6.1.2.1.17.4.3.1.2"
+
+	macResults, err := snmp.BulkWalkAll(macOID)
+	if err != nil {
+		return
+	}
+
+	portResults, err := snmp.BulkWalkAll(portOID)
+	if err != nil {
+		return
+	}
+
+	portMap := make(map[string]int)
+	for _, result := range portResults {
+		if result.Type == gosnmp.Integer {
+			oidSuffix := result.Name[len(portOID)+1:]
+			portMap[oidSuffix] = result.Value.(int)
+		}
+	}
+
+	bridgePortToIfIndex := t.getBridgePortMapping(snmp)
+	ifNames := t.getInterfaceNames(snmp)
+
+	for _, result := range macResults {
+		if result.Type == gosnmp.OctetString {
+			macBytes := result.Value.([]byte)
+			if len(macBytes) != 6 {
+				continue
+			}
+
+			mac := net.HardwareAddr(macBytes)
+			if isBroadcastOrZero(mac) {
+				continue
+			}
+
+			oidSuffix := result.Name[len(macOID)+1:]
+			bridgePort, exists := portMap[oidSuffix]
+			if !exists {
+				continue
+			}
+
+			ifIndex, exists := bridgePortToIfIndex[bridgePort]
+			if !exists {
+				ifIndex = bridgePort
+			}
+
+			ifName := ifNames[ifIndex]
+			if ifName == "" {
+				ifName = "??"
+			}
+
+			t.nodes.Update(nil, []net.HardwareAddr{mac}, ifName, "", "snmp")
+		}
+	}
+
+	log.Printf("[snmp] queried bridge mib on %s", deviceIP)
+}
+
+func (t *Tendrils) queryARPTable(snmp *gosnmp.GoSNMP, deviceIP net.IP) {
+	macOID := "1.3.6.1.2.1.4.22.1.2"
+	ipOID := "1.3.6.1.2.1.4.22.1.3"
+	ifIndexOID := "1.3.6.1.2.1.4.22.1.1"
+
+	macResults, err := snmp.BulkWalkAll(macOID)
+	if err != nil {
+		return
+	}
+
+	ipResults, err := snmp.BulkWalkAll(ipOID)
+	if err != nil {
+		return
+	}
+
+	ifIndexResults, err := snmp.BulkWalkAll(ifIndexOID)
+	if err != nil {
+		return
+	}
+
+	ipMap := make(map[string]net.IP)
+	for _, result := range ipResults {
+		if result.Type == gosnmp.IPAddress {
+			oidSuffix := result.Name[len(ipOID)+1:]
+			ipBytes := result.Value.([]byte)
+			ipMap[oidSuffix] = net.IP(ipBytes)
+		}
+	}
+
+	ifIndexMap := make(map[string]int)
+	for _, result := range ifIndexResults {
+		if result.Type == gosnmp.Integer {
+			oidSuffix := result.Name[len(ifIndexOID)+1:]
+			ifIndexMap[oidSuffix] = result.Value.(int)
+		}
+	}
+
+	ifNames := t.getInterfaceNames(snmp)
+
+	for _, result := range macResults {
+		if result.Type == gosnmp.OctetString {
+			macBytes := result.Value.([]byte)
+			if len(macBytes) != 6 {
+				continue
+			}
+
+			mac := net.HardwareAddr(macBytes)
+			if isBroadcastOrZero(mac) {
+				continue
+			}
+
+			oidSuffix := result.Name[len(macOID)+1:]
+			ip, hasIP := ipMap[oidSuffix]
+			ifIndex, hasIfIndex := ifIndexMap[oidSuffix]
+
+			var ips []net.IP
+			if hasIP {
+				ips = []net.IP{ip}
+			}
+
+			ifName := ""
+			if hasIfIndex {
+				ifName = ifNames[ifIndex]
+			}
+			if ifName == "" {
+				ifName = "??"
+			}
+
+			t.nodes.Update(ips, []net.HardwareAddr{mac}, ifName, "", "snmp")
+		}
+	}
+
+	log.Printf("[snmp] queried arp table on %s", deviceIP)
+}
+
+func (t *Tendrils) getBridgePortMapping(snmp *gosnmp.GoSNMP) map[int]int {
+	oid := "1.3.6.1.2.1.17.1.4.1.2"
+
+	results, err := snmp.BulkWalkAll(oid)
+	if err != nil {
+		return nil
+	}
+
+	mapping := make(map[int]int)
+	for _, result := range results {
+		if result.Type == gosnmp.Integer {
+			oidParts := result.Name[len(oid)+1:]
+			var bridgePort int
+			_, err := fmt.Sscanf(oidParts, "%d", &bridgePort)
+			if err != nil {
+				continue
+			}
+			ifIndex := result.Value.(int)
+			mapping[bridgePort] = ifIndex
+		}
+	}
+
+	return mapping
+}
+
+func (t *Tendrils) getInterfaceNames(snmp *gosnmp.GoSNMP) map[int]string {
+	oid := "1.3.6.1.2.1.2.2.1.2"
+
+	results, err := snmp.BulkWalkAll(oid)
+	if err != nil {
+		return nil
+	}
+
+	names := make(map[int]string)
+	for _, result := range results {
+		if result.Type == gosnmp.OctetString {
+			oidParts := result.Name[len(oid)+1:]
+			var ifIndex int
+			_, err := fmt.Sscanf(oidParts, "%d", &ifIndex)
+			if err != nil {
+				continue
+			}
+			name := string(result.Value.([]byte))
+			names[ifIndex] = name
+		}
+	}
+
+	return names
+}

tendrils.go

@@ -24,6 +24,7 @@ func (t *Tendrils) Run() {
 	defer cancel()
 
 	go t.pollARP(ctx)
+	go t.pollSNMP(ctx)
 
 	ticker := time.NewTicker(1 * time.Second)
 	defer ticker.Stop()