| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | package snmputils |
| 4 | |
| 5 | import ( |
| 6 | "fmt" |
| 7 | "strings" |
| 8 | |
| 9 | "github.com/gosnmp/gosnmp" |
| 10 | ) |
| 11 | |
| 12 | const ( |
| 13 | OidSnmpEngineTime = "1.3.6.1.6.3.10.2.1.3.0" |
| 14 | OidHrSystemUptime = "1.3.6.1.2.1.25.1.1.0" |
| 15 | OidSysUpTime = "1.3.6.1.2.1.1.3.0" |
| 16 | sysUptimeTimeTicks = 0.01 |
| 17 | ) |
| 18 | |
| 19 | type sysUptimeSource struct { |
| 20 | oid string |
| 21 | scale float64 |
| 22 | } |
| 23 | |
| 24 | var sysUptimeSources = []sysUptimeSource{ |
| 25 | {oid: OidSnmpEngineTime}, |
| 26 | {oid: OidHrSystemUptime, scale: sysUptimeTimeTicks}, |
| 27 | {oid: OidSysUpTime, scale: sysUptimeTimeTicks}, |
| 28 | } |
| 29 | |
| 30 | func GetSysUptime(client gosnmp.Handler) (int64, error) { |
| 31 | packet, err := client.Get(sysUptimeOIDs()) |
| 32 | if err != nil { |
| 33 | return 0, err |
| 34 | } |
| 35 | if packet == nil || len(packet.Variables) == 0 { |
| 36 | return 0, nil |
| 37 | } |
| 38 | |
| 39 | pdusByOID := make(map[string]gosnmp.SnmpPDU, len(packet.Variables)) |
| 40 | for _, pdu := range packet.Variables { |
| 41 | pdusByOID[strings.TrimPrefix(pdu.Name, ".")] = pdu |
| 42 | } |
| 43 | |
| 44 | var lastErr error |
| 45 | for _, source := range sysUptimeSources { |
| 46 | pdu, ok := pdusByOID[source.oid] |
| 47 | if !ok || !isSysUptimePduWithData(pdu) { |
| 48 | continue |
| 49 | } |
| 50 | |
| 51 | value, err := sysUptimePduValue(pdu) |
| 52 | if err != nil { |
| 53 | lastErr = fmt.Errorf("OID '%s': %w", source.oid, err) |
| 54 | continue |
| 55 | } |
| 56 | if source.scale != 0 { |
| 57 | value = int64(float64(value) * source.scale) |
| 58 | } |
| 59 | if value > 0 { |
| 60 | return value, nil |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | return 0, lastErr |
| 65 | } |
| 66 | |
| 67 | func sysUptimeOIDs() []string { |
| 68 | oids := make([]string, 0, len(sysUptimeSources)) |
| 69 | for _, source := range sysUptimeSources { |
| 70 | oids = append(oids, source.oid) |
| 71 | } |
| 72 | return oids |
| 73 | } |
| 74 | |
| 75 | func sysUptimePduValue(pdu gosnmp.SnmpPDU) (int64, error) { |
| 76 | if !isSysUptimeNumericPdu(pdu) { |
| 77 | return 0, fmt.Errorf("cannot convert %T to numeric uptime", pdu.Value) |
| 78 | } |
| 79 | return gosnmp.ToBigInt(pdu.Value).Int64(), nil |
| 80 | } |
| 81 | |
| 82 | func isSysUptimePduWithData(pdu gosnmp.SnmpPDU) bool { |
| 83 | switch pdu.Type { |
| 84 | case gosnmp.NoSuchObject, |
| 85 | gosnmp.NoSuchInstance, |
| 86 | gosnmp.Null, |
| 87 | gosnmp.EndOfMibView: |
| 88 | return false |
| 89 | default: |
| 90 | return true |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | func isSysUptimeNumericPdu(pdu gosnmp.SnmpPDU) bool { |
| 95 | switch pdu.Type { |
| 96 | case gosnmp.Counter32, |
| 97 | gosnmp.Counter64, |
| 98 | gosnmp.Integer, |
| 99 | gosnmp.Gauge32, |
| 100 | gosnmp.Uinteger32, |
| 101 | gosnmp.TimeTicks: |
| 102 | return true |
| 103 | default: |
| 104 | return false |
| 105 | } |
| 106 | } |