telegraf/plugins/inputs/snmp/snmp.go

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package snmp
import (
"bytes"
"fmt"
"math"
"net"
"os/exec"
"strconv"
"strings"
"sync"
"time"
"github.com/influxdata/telegraf"
"github.com/influxdata/telegraf/internal"
"github.com/influxdata/telegraf/plugins/inputs"
"github.com/soniah/gosnmp"
)
const description = `Retrieves SNMP values from remote agents`
const sampleConfig = `
agents = [ "127.0.0.1:161" ]
## Timeout for each SNMP query.
timeout = "5s"
## Number of retries to attempt within timeout.
retries = 3
## SNMP version, values can be 1, 2, or 3
version = 2
## SNMP community string.
community = "public"
## The GETBULK max-repetitions parameter
max_repetitions = 10
## SNMPv3 auth parameters
#sec_name = "myuser"
#auth_protocol = "md5" # Values: "MD5", "SHA", ""
#auth_password = "pass"
#sec_level = "authNoPriv" # Values: "noAuthNoPriv", "authNoPriv", "authPriv"
#context_name = ""
#priv_protocol = "" # Values: "DES", "AES", ""
#priv_password = ""
## measurement name
name = "system"
[[inputs.snmp.field]]
name = "hostname"
oid = ".1.0.0.1.1"
[[inputs.snmp.field]]
name = "uptime"
oid = ".1.0.0.1.2"
[[inputs.snmp.field]]
name = "load"
oid = ".1.0.0.1.3"
[[inputs.snmp.field]]
oid = "HOST-RESOURCES-MIB::hrMemorySize"
[[inputs.snmp.table]]
## measurement name
name = "remote_servers"
inherit_tags = [ "hostname" ]
[[inputs.snmp.table.field]]
name = "server"
oid = ".1.0.0.0.1.0"
is_tag = true
[[inputs.snmp.table.field]]
name = "connections"
oid = ".1.0.0.0.1.1"
[[inputs.snmp.table.field]]
name = "latency"
oid = ".1.0.0.0.1.2"
[[inputs.snmp.table]]
## auto populate table's fields using the MIB
oid = "HOST-RESOURCES-MIB::hrNetworkTable"
`
// execCommand is so tests can mock out exec.Command usage.
var execCommand = exec.Command
// execCmd executes the specified command, returning the STDOUT content.
// If command exits with error status, the output is captured into the returned error.
func execCmd(arg0 string, args ...string) ([]byte, error) {
out, err := execCommand(arg0, args...).Output()
if err != nil {
if err, ok := err.(*exec.ExitError); ok {
return nil, NestedError{
Err: err,
NestedErr: fmt.Errorf("%s", bytes.TrimRight(err.Stderr, "\n")),
}
}
return nil, err
}
return out, nil
}
// Snmp holds the configuration for the plugin.
type Snmp struct {
// The SNMP agent to query. Format is ADDR[:PORT] (e.g. 1.2.3.4:161).
Agents []string
// Timeout to wait for a response.
Timeout internal.Duration
Retries int
// Values: 1, 2, 3
Version uint8
// Parameters for Version 1 & 2
Community string
// Parameters for Version 2 & 3
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MaxRepetitions uint8
// Parameters for Version 3
ContextName string
// Values: "noAuthNoPriv", "authNoPriv", "authPriv"
SecLevel string
SecName string
// Values: "MD5", "SHA", "". Default: ""
AuthProtocol string
AuthPassword string
// Values: "DES", "AES", "". Default: ""
PrivProtocol string
PrivPassword string
EngineID string
EngineBoots uint32
EngineTime uint32
Tables []Table `toml:"table"`
// Name & Fields are the elements of a Table.
// Telegraf chokes if we try to embed a Table. So instead we have to embed the
// fields of a Table, and construct a Table during runtime.
Name string
Fields []Field `toml:"field"`
connectionCache map[string]snmpConnection
initialized bool
}
func (s *Snmp) init() error {
if s.initialized {
return nil
}
for i := range s.Tables {
if err := s.Tables[i].init(); err != nil {
return Errorf(err, "initializing table %s", s.Tables[i].Name)
}
}
for i := range s.Fields {
if err := s.Fields[i].init(); err != nil {
return Errorf(err, "initializing field %s", s.Fields[i].Name)
}
}
s.initialized = true
return nil
}
// Table holds the configuration for a SNMP table.
type Table struct {
// Name will be the name of the measurement.
Name string
// Which tags to inherit from the top-level config.
InheritTags []string
// Fields is the tags and values to look up.
Fields []Field `toml:"field"`
// OID for automatic field population.
// If provided, init() will populate Fields with all the table columns of the
// given OID.
Oid string
initialized bool
}
// init() builds & initializes the nested fields.
func (t *Table) init() error {
if t.initialized {
return nil
}
if err := t.initBuild(); err != nil {
return err
}
// initialize all the nested fields
for i := range t.Fields {
if err := t.Fields[i].init(); err != nil {
return Errorf(err, "initializing field %s", t.Fields[i].Name)
}
}
t.initialized = true
return nil
}
// initBuild initializes the table if it has an OID configured. If so, the
// net-snmp tools will be used to look up the OID and auto-populate the table's
// fields.
func (t *Table) initBuild() error {
if t.Oid == "" {
return nil
}
_, _, oidText, fields, err := snmpTable(t.Oid)
if err != nil {
return err
}
if t.Name == "" {
t.Name = oidText
}
t.Fields = append(t.Fields, fields...)
return nil
}
// Field holds the configuration for a Field to look up.
type Field struct {
// Name will be the name of the field.
Name string
// OID is prefix for this field. The plugin will perform a walk through all
// OIDs with this as their parent. For each value found, the plugin will strip
// off the OID prefix, and use the remainder as the index. For multiple fields
// to show up in the same row, they must share the same index.
Oid string
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// OidIndexSuffix is the trailing sub-identifier on a table record OID that will be stripped off to get the record's index.
OidIndexSuffix string
// IsTag controls whether this OID is output as a tag or a value.
IsTag bool
// Conversion controls any type conversion that is done on the value.
// "float"/"float(0)" will convert the value into a float.
// "float(X)" will convert the value into a float, and then move the decimal before Xth right-most digit.
// "int" will conver the value into an integer.
// "hwaddr" will convert a 6-byte string to a MAC address.
// "ipaddr" will convert the value to an IPv4 or IPv6 address.
Conversion string
initialized bool
}
// init() converts OID names to numbers, and sets the .Name attribute if unset.
func (f *Field) init() error {
if f.initialized {
return nil
}
_, oidNum, oidText, conversion, err := snmpTranslate(f.Oid)
if err != nil {
return Errorf(err, "translating")
}
f.Oid = oidNum
if f.Name == "" {
f.Name = oidText
}
if f.Conversion == "" {
f.Conversion = conversion
}
//TODO use textual convention conversion from the MIB
f.initialized = true
return nil
}
// RTable is the resulting table built from a Table.
type RTable struct {
// Name is the name of the field, copied from Table.Name.
Name string
// Time is the time the table was built.
Time time.Time
// Rows are the rows that were found, one row for each table OID index found.
Rows []RTableRow
}
// RTableRow is the resulting row containing all the OID values which shared
// the same index.
type RTableRow struct {
// Tags are all the Field values which had IsTag=true.
Tags map[string]string
// Fields are all the Field values which had IsTag=false.
Fields map[string]interface{}
}
// NestedError wraps an error returned from deeper in the code.
type NestedError struct {
// Err is the error from where the NestedError was constructed.
Err error
// NestedError is the error that was passed back from the called function.
NestedErr error
}
// Error returns a concatenated string of all the nested errors.
func (ne NestedError) Error() string {
return ne.Err.Error() + ": " + ne.NestedErr.Error()
}
// Errorf is a convenience function for constructing a NestedError.
func Errorf(err error, msg string, format ...interface{}) error {
return NestedError{
NestedErr: err,
Err: fmt.Errorf(msg, format...),
}
}
func init() {
inputs.Add("snmp", func() telegraf.Input {
return &Snmp{
Retries: 3,
MaxRepetitions: 10,
Timeout: internal.Duration{Duration: 5 * time.Second},
Version: 2,
Community: "public",
}
})
}
// SampleConfig returns the default configuration of the input.
func (s *Snmp) SampleConfig() string {
return sampleConfig
}
// Description returns a one-sentence description on the input.
func (s *Snmp) Description() string {
return description
}
// Gather retrieves all the configured fields and tables.
// Any error encountered does not halt the process. The errors are accumulated
// and returned at the end.
func (s *Snmp) Gather(acc telegraf.Accumulator) error {
if err := s.init(); err != nil {
return err
}
for _, agent := range s.Agents {
gs, err := s.getConnection(agent)
if err != nil {
acc.AddError(Errorf(err, "agent %s", agent))
continue
}
// First is the top-level fields. We treat the fields as table prefixes with an empty index.
t := Table{
Name: s.Name,
Fields: s.Fields,
}
topTags := map[string]string{}
if err := s.gatherTable(acc, gs, t, topTags, false); err != nil {
acc.AddError(Errorf(err, "agent %s", agent))
}
// Now is the real tables.
for _, t := range s.Tables {
if err := s.gatherTable(acc, gs, t, topTags, true); err != nil {
acc.AddError(Errorf(err, "agent %s: gathering table %s", agent, t.Name))
}
}
}
return nil
}
func (s *Snmp) gatherTable(acc telegraf.Accumulator, gs snmpConnection, t Table, topTags map[string]string, walk bool) error {
rt, err := t.Build(gs, walk)
if err != nil {
return err
}
for _, tr := range rt.Rows {
if !walk {
// top-level table. Add tags to topTags.
for k, v := range tr.Tags {
topTags[k] = v
}
} else {
// real table. Inherit any specified tags.
for _, k := range t.InheritTags {
if v, ok := topTags[k]; ok {
tr.Tags[k] = v
}
}
}
if _, ok := tr.Tags["agent_host"]; !ok {
tr.Tags["agent_host"] = gs.Host()
}
acc.AddFields(rt.Name, tr.Fields, tr.Tags, rt.Time)
}
return nil
}
// Build retrieves all the fields specified in the table and constructs the RTable.
func (t Table) Build(gs snmpConnection, walk bool) (*RTable, error) {
rows := map[string]RTableRow{}
tagCount := 0
for _, f := range t.Fields {
if f.IsTag {
tagCount++
}
if len(f.Oid) == 0 {
return nil, fmt.Errorf("cannot have empty OID on field %s", f.Name)
}
var oid string
if f.Oid[0] == '.' {
oid = f.Oid
} else {
// make sure OID has "." because the BulkWalkAll results do, and the prefix needs to match
oid = "." + f.Oid
}
// ifv contains a mapping of table OID index to field value
ifv := map[string]interface{}{}
if !walk {
// This is used when fetching non-table fields. Fields configured a the top
// scope of the plugin.
// We fetch the fields directly, and add them to ifv as if the index were an
// empty string. This results in all the non-table fields sharing the same
// index, and being added on the same row.
if pkt, err := gs.Get([]string{oid}); err != nil {
return nil, Errorf(err, "performing get on field %s", f.Name)
} else if pkt != nil && len(pkt.Variables) > 0 && pkt.Variables[0].Type != gosnmp.NoSuchObject && pkt.Variables[0].Type != gosnmp.NoSuchInstance {
ent := pkt.Variables[0]
fv, err := fieldConvert(f.Conversion, ent.Value)
if err != nil {
return nil, Errorf(err, "converting %q (OID %s) for field %s", ent.Value, ent.Name, f.Name)
}
if fvs, ok := fv.(string); !ok || fvs != "" {
ifv[""] = fv
}
}
} else {
err := gs.Walk(oid, func(ent gosnmp.SnmpPDU) error {
if len(ent.Name) <= len(oid) || ent.Name[:len(oid)+1] != oid+"." {
return NestedError{} // break the walk
}
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idx := ent.Name[len(oid):]
if f.OidIndexSuffix != "" {
if !strings.HasSuffix(idx, f.OidIndexSuffix) {
// this entry doesn't match our OidIndexSuffix. skip it
return nil
}
idx = idx[:len(idx)-len(f.OidIndexSuffix)]
}
fv, err := fieldConvert(f.Conversion, ent.Value)
if err != nil {
return Errorf(err, "converting %q (OID %s) for field %s", ent.Value, ent.Name, f.Name)
}
if fvs, ok := fv.(string); !ok || fvs != "" {
ifv[idx] = fv
}
return nil
})
if err != nil {
if _, ok := err.(NestedError); !ok {
return nil, Errorf(err, "performing bulk walk for field %s", f.Name)
}
}
}
for i, v := range ifv {
rtr, ok := rows[i]
if !ok {
rtr = RTableRow{}
rtr.Tags = map[string]string{}
rtr.Fields = map[string]interface{}{}
rows[i] = rtr
}
if f.IsTag {
if vs, ok := v.(string); ok {
rtr.Tags[f.Name] = vs
} else {
rtr.Tags[f.Name] = fmt.Sprintf("%v", v)
}
} else {
rtr.Fields[f.Name] = v
}
}
}
rt := RTable{
Name: t.Name,
Time: time.Now(), //TODO record time at start
Rows: make([]RTableRow, 0, len(rows)),
}
for _, r := range rows {
if len(r.Tags) < tagCount {
// don't add rows which are missing tags, as without tags you can't filter
continue
}
rt.Rows = append(rt.Rows, r)
}
return &rt, nil
}
// snmpConnection is an interface which wraps a *gosnmp.GoSNMP object.
// We interact through an interface so we can mock it out in tests.
type snmpConnection interface {
Host() string
//BulkWalkAll(string) ([]gosnmp.SnmpPDU, error)
Walk(string, gosnmp.WalkFunc) error
Get(oids []string) (*gosnmp.SnmpPacket, error)
}
// gosnmpWrapper wraps a *gosnmp.GoSNMP object so we can use it as a snmpConnection.
type gosnmpWrapper struct {
*gosnmp.GoSNMP
}
// Host returns the value of GoSNMP.Target.
func (gsw gosnmpWrapper) Host() string {
return gsw.Target
}
// Walk wraps GoSNMP.Walk() or GoSNMP.BulkWalk(), depending on whether the
// connection is using SNMPv1 or newer.
// Also, if any error is encountered, it will just once reconnect and try again.
func (gsw gosnmpWrapper) Walk(oid string, fn gosnmp.WalkFunc) error {
var err error
// On error, retry once.
// Unfortunately we can't distinguish between an error returned by gosnmp, and one returned by the walk function.
for i := 0; i < 2; i++ {
if gsw.Version == gosnmp.Version1 {
err = gsw.GoSNMP.Walk(oid, fn)
} else {
err = gsw.GoSNMP.BulkWalk(oid, fn)
}
if err == nil {
return nil
}
if err := gsw.GoSNMP.Connect(); err != nil {
return Errorf(err, "reconnecting")
}
}
return err
}
// Get wraps GoSNMP.GET().
// If any error is encountered, it will just once reconnect and try again.
func (gsw gosnmpWrapper) Get(oids []string) (*gosnmp.SnmpPacket, error) {
var err error
var pkt *gosnmp.SnmpPacket
for i := 0; i < 2; i++ {
pkt, err = gsw.GoSNMP.Get(oids)
if err == nil {
return pkt, nil
}
if err := gsw.GoSNMP.Connect(); err != nil {
return nil, Errorf(err, "reconnecting")
}
}
return nil, err
}
// getConnection creates a snmpConnection (*gosnmp.GoSNMP) object and caches the
// result using `agent` as the cache key.
func (s *Snmp) getConnection(agent string) (snmpConnection, error) {
if s.connectionCache == nil {
s.connectionCache = map[string]snmpConnection{}
}
if gs, ok := s.connectionCache[agent]; ok {
return gs, nil
}
gs := gosnmpWrapper{&gosnmp.GoSNMP{}}
host, portStr, err := net.SplitHostPort(agent)
if err != nil {
if err, ok := err.(*net.AddrError); !ok || err.Err != "missing port in address" {
return nil, Errorf(err, "parsing host")
}
host = agent
portStr = "161"
}
gs.Target = host
port, err := strconv.ParseUint(portStr, 10, 16)
if err != nil {
return nil, Errorf(err, "parsing port")
}
gs.Port = uint16(port)
gs.Timeout = s.Timeout.Duration
gs.Retries = s.Retries
switch s.Version {
case 3:
gs.Version = gosnmp.Version3
case 2, 0:
gs.Version = gosnmp.Version2c
case 1:
gs.Version = gosnmp.Version1
default:
return nil, fmt.Errorf("invalid version")
}
if s.Version < 3 {
if s.Community == "" {
gs.Community = "public"
} else {
gs.Community = s.Community
}
}
gs.MaxRepetitions = s.MaxRepetitions
if s.Version == 3 {
gs.ContextName = s.ContextName
sp := &gosnmp.UsmSecurityParameters{}
gs.SecurityParameters = sp
gs.SecurityModel = gosnmp.UserSecurityModel
switch strings.ToLower(s.SecLevel) {
case "noauthnopriv", "":
gs.MsgFlags = gosnmp.NoAuthNoPriv
case "authnopriv":
gs.MsgFlags = gosnmp.AuthNoPriv
case "authpriv":
gs.MsgFlags = gosnmp.AuthPriv
default:
return nil, fmt.Errorf("invalid secLevel")
}
sp.UserName = s.SecName
switch strings.ToLower(s.AuthProtocol) {
case "md5":
sp.AuthenticationProtocol = gosnmp.MD5
case "sha":
sp.AuthenticationProtocol = gosnmp.SHA
case "":
sp.AuthenticationProtocol = gosnmp.NoAuth
default:
return nil, fmt.Errorf("invalid authProtocol")
}
sp.AuthenticationPassphrase = s.AuthPassword
switch strings.ToLower(s.PrivProtocol) {
case "des":
sp.PrivacyProtocol = gosnmp.DES
case "aes":
sp.PrivacyProtocol = gosnmp.AES
case "":
sp.PrivacyProtocol = gosnmp.NoPriv
default:
return nil, fmt.Errorf("invalid privProtocol")
}
sp.PrivacyPassphrase = s.PrivPassword
sp.AuthoritativeEngineID = s.EngineID
sp.AuthoritativeEngineBoots = s.EngineBoots
sp.AuthoritativeEngineTime = s.EngineTime
}
if err := gs.Connect(); err != nil {
return nil, Errorf(err, "setting up connection")
}
s.connectionCache[agent] = gs
return gs, nil
}
// fieldConvert converts from any type according to the conv specification
// "float"/"float(0)" will convert the value into a float.
// "float(X)" will convert the value into a float, and then move the decimal before Xth right-most digit.
// "int" will convert the value into an integer.
// "hwaddr" will convert the value into a MAC address.
// "ipaddr" will convert the value into into an IP address.
// "" will convert a byte slice into a string.
func fieldConvert(conv string, v interface{}) (interface{}, error) {
if conv == "" {
if bs, ok := v.([]byte); ok {
return string(bs), nil
}
return v, nil
}
var d int
if _, err := fmt.Sscanf(conv, "float(%d)", &d); err == nil || conv == "float" {
switch vt := v.(type) {
case float32:
v = float64(vt) / math.Pow10(d)
case float64:
v = float64(vt) / math.Pow10(d)
case int:
v = float64(vt) / math.Pow10(d)
case int8:
v = float64(vt) / math.Pow10(d)
case int16:
v = float64(vt) / math.Pow10(d)
case int32:
v = float64(vt) / math.Pow10(d)
case int64:
v = float64(vt) / math.Pow10(d)
case uint:
v = float64(vt) / math.Pow10(d)
case uint8:
v = float64(vt) / math.Pow10(d)
case uint16:
v = float64(vt) / math.Pow10(d)
case uint32:
v = float64(vt) / math.Pow10(d)
case uint64:
v = float64(vt) / math.Pow10(d)
case []byte:
vf, _ := strconv.ParseFloat(string(vt), 64)
v = vf / math.Pow10(d)
case string:
vf, _ := strconv.ParseFloat(vt, 64)
v = vf / math.Pow10(d)
}
return v, nil
}
if conv == "int" {
switch vt := v.(type) {
case float32:
v = int64(vt)
case float64:
v = int64(vt)
case int:
v = int64(vt)
case int8:
v = int64(vt)
case int16:
v = int64(vt)
case int32:
v = int64(vt)
case int64:
v = int64(vt)
case uint:
v = int64(vt)
case uint8:
v = int64(vt)
case uint16:
v = int64(vt)
case uint32:
v = int64(vt)
case uint64:
v = int64(vt)
case []byte:
v, _ = strconv.Atoi(string(vt))
case string:
v, _ = strconv.Atoi(vt)
}
return v, nil
}
if conv == "hwaddr" {
switch vt := v.(type) {
case string:
v = net.HardwareAddr(vt).String()
case []byte:
v = net.HardwareAddr(vt).String()
default:
return nil, fmt.Errorf("invalid type (%T) for hwaddr conversion", v)
}
return v, nil
}
if conv == "ipaddr" {
var ipbs []byte
switch vt := v.(type) {
case string:
ipbs = []byte(vt)
case []byte:
ipbs = vt
default:
return nil, fmt.Errorf("invalid type (%T) for ipaddr conversion", v)
}
switch len(ipbs) {
case 4, 16:
v = net.IP(ipbs).String()
default:
return nil, fmt.Errorf("invalid length (%d) for ipaddr conversion", len(ipbs))
}
return v, nil
}
return nil, fmt.Errorf("invalid conversion type '%s'", conv)
}
type snmpTableCache struct {
mibName string
oidNum string
oidText string
fields []Field
err error
}
var snmpTableCaches map[string]snmpTableCache
var snmpTableCachesLock sync.Mutex
// snmpTable resolves the given OID as a table, providing information about the
// table and fields within.
func snmpTable(oid string) (mibName string, oidNum string, oidText string, fields []Field, err error) {
snmpTableCachesLock.Lock()
if snmpTableCaches == nil {
snmpTableCaches = map[string]snmpTableCache{}
}
var stc snmpTableCache
var ok bool
if stc, ok = snmpTableCaches[oid]; !ok {
stc.mibName, stc.oidNum, stc.oidText, stc.fields, stc.err = snmpTableCall(oid)
snmpTableCaches[oid] = stc
}
snmpTableCachesLock.Unlock()
return stc.mibName, stc.oidNum, stc.oidText, stc.fields, stc.err
}
func snmpTableCall(oid string) (mibName string, oidNum string, oidText string, fields []Field, err error) {
mibName, oidNum, oidText, _, err = snmpTranslate(oid)
if err != nil {
return "", "", "", nil, Errorf(err, "translating")
}
mibPrefix := mibName + "::"
oidFullName := mibPrefix + oidText
// first attempt to get the table's tags
tagOids := map[string]struct{}{}
// We have to guess that the "entry" oid is `oid+".1"`. snmptable and snmptranslate don't seem to have a way to provide the info.
if out, err := execCmd("snmptranslate", "-Td", oidFullName+".1"); err == nil {
lines := bytes.Split(out, []byte{'\n'})
for _, line := range lines {
if !bytes.HasPrefix(line, []byte(" INDEX")) {
continue
}
i := bytes.Index(line, []byte("{ "))
if i == -1 { // parse error
continue
}
line = line[i+2:]
i = bytes.Index(line, []byte(" }"))
if i == -1 { // parse error
continue
}
line = line[:i]
for _, col := range bytes.Split(line, []byte(", ")) {
tagOids[mibPrefix+string(col)] = struct{}{}
}
}
}
// this won't actually try to run a query. The `-Ch` will just cause it to dump headers.
out, err := execCmd("snmptable", "-Ch", "-Cl", "-c", "public", "127.0.0.1", oidFullName)
if err != nil {
return "", "", "", nil, Errorf(err, "getting table columns")
}
cols := bytes.SplitN(out, []byte{'\n'}, 2)[0]
if len(cols) == 0 {
return "", "", "", nil, fmt.Errorf("could not find any columns in table")
}
for _, col := range bytes.Split(cols, []byte{' '}) {
if len(col) == 0 {
continue
}
col := string(col)
_, isTag := tagOids[mibPrefix+col]
fields = append(fields, Field{Name: col, Oid: mibPrefix + col, IsTag: isTag})
}
return mibName, oidNum, oidText, fields, err
}
type snmpTranslateCache struct {
mibName string
oidNum string
oidText string
conversion string
err error
}
var snmpTranslateCachesLock sync.Mutex
var snmpTranslateCaches map[string]snmpTranslateCache
// snmpTranslate resolves the given OID.
func snmpTranslate(oid string) (mibName string, oidNum string, oidText string, conversion string, err error) {
snmpTranslateCachesLock.Lock()
if snmpTranslateCaches == nil {
snmpTranslateCaches = map[string]snmpTranslateCache{}
}
var stc snmpTranslateCache
var ok bool
if stc, ok = snmpTranslateCaches[oid]; !ok {
// This will result in only one call to snmptranslate running at a time.
// We could speed it up by putting a lock in snmpTranslateCache and then
// returning it immediately, and multiple callers would then release the
// snmpTranslateCachesLock and instead wait on the individual
// snmpTranlsation.Lock to release. But I don't know that the extra complexity
// is worth it. Especially when it would slam the system pretty hard if lots
// of lookups are being perfomed.
stc.mibName, stc.oidNum, stc.oidText, stc.conversion, stc.err = snmpTranslateCall(oid)
snmpTranslateCaches[oid] = stc
}
snmpTranslateCachesLock.Unlock()
return stc.mibName, stc.oidNum, stc.oidText, stc.conversion, stc.err
}
func snmpTranslateCall(oid string) (mibName string, oidNum string, oidText string, conversion string, err error) {
var out []byte
if strings.ContainsAny(oid, ":abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ") {
out, err = execCmd("snmptranslate", "-Td", "-Ob", oid)
} else {
out, err = execCmd("snmptranslate", "-Td", "-Ob", "-m", "all", oid)
if err, ok := err.(*exec.Error); ok && err.Err == exec.ErrNotFound {
// Silently discard error if snmptranslate not found and we have a numeric OID.
// Meaning we can get by without the lookup.
return "", oid, oid, "", nil
}
}
if err != nil {
return "", "", "", "", err
}
bb := bytes.NewBuffer(out)
oidText, err = bb.ReadString('\n')
if err != nil {
return "", "", "", "", Errorf(err, "getting OID text")
}
oidText = oidText[:len(oidText)-1]
i := strings.Index(oidText, "::")
if i == -1 {
// was not found in MIB.
if bytes.Index(bb.Bytes(), []byte(" [TRUNCATED]")) >= 0 {
return "", oid, oid, "", nil
}
// not truncated, but not fully found. We still need to parse out numeric OID, so keep going
oidText = oid
} else {
mibName = oidText[:i]
oidText = oidText[i+2:]
}
if i := bytes.Index(bb.Bytes(), []byte(" -- TEXTUAL CONVENTION ")); i != -1 {
bb.Next(i + len(" -- TEXTUAL CONVENTION "))
tc, err := bb.ReadString('\n')
if err != nil {
return "", "", "", "", Errorf(err, "getting textual convention")
}
tc = tc[:len(tc)-1]
switch tc {
case "MacAddress", "PhysAddress":
conversion = "hwaddr"
case "InetAddressIPv4", "InetAddressIPv6", "InetAddress":
conversion = "ipaddr"
}
}
i = bytes.Index(bb.Bytes(), []byte("::= { "))
bb.Next(i + len("::= { "))
objs, err := bb.ReadString('}')
if err != nil {
return "", "", "", "", Errorf(err, "getting numeric oid")
}
objs = objs[:len(objs)-1]
for _, obj := range strings.Split(objs, " ") {
if len(obj) == 0 {
continue
}
if i := strings.Index(obj, "("); i != -1 {
obj = obj[i+1:]
oidNum += "." + obj[:strings.Index(obj, ")")]
} else {
oidNum += "." + obj
}
}
return mibName, oidNum, oidText, conversion, nil
}