{,x-pack/}packetbeat: remove dead code and unused fields, vars, const…

…s and comments (#30489)

This removes the majority of unused code identified by running:

staticcheck -checks 'U*' ./{,x-pack/}packetbeat/...

Care has been taken to not remove platform-specific code and mage-required code.

packetbeat/flows/flowid_test.go

@@ -54,14 +54,6 @@ func addVLan(u []byte) applyAddr {
 	}
 }
 
-func addUDP(a, b []byte) applyAddr {
-	src := binary.LittleEndian.Uint16(a)
-	dst := binary.LittleEndian.Uint16(b)
-	return func(f *FlowID) {
-		f.AddUDP(src, dst)
-	}
-}
-
 func addTCP(a, b []byte) applyAddr {
 	src := binary.LittleEndian.Uint16(a)
 	dst := binary.LittleEndian.Uint16(b)

packetbeat/npcap/npcap.go

@@ -15,19 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
-// Package npcap handles fetching and installing Npcap fow Windows.
-//
-// The npcap package interacts with a registry and download server that
-// provides a current_version end point that serves a JSON message that
-// corresponds to the this Go type:
-//
-//  struct {
-//  	Version string // The semverish version of the Npcap installer.
-//  	URL     string // The location of the Npcap installer.
-//  	Hash    string // The sha256 hash of the Npcap installer.
-//  }
-//
-// The URL field will point to the location of anb Npcap installer.
+// Package npcap handles fetching and installing Npcap for Windows.
 package npcap
 
 import (

packetbeat/protos/cassandra/internal/gocql/marshal.go

@@ -271,60 +271,6 @@ func (t Type) String() string {
 	}
 }
 
-const (
-	apacheCassandraTypePrefix = "org.apache.cassandra.db.marshal."
-)
-
-// get Apache Cassandra types
-func getApacheCassandraType(class string) Type {
-	switch strings.TrimPrefix(class, apacheCassandraTypePrefix) {
-	case "AsciiType":
-		return TypeASCII
-	case "LongType":
-		return TypeBigInt
-	case "BytesType":
-		return TypeBlob
-	case "BooleanType":
-		return TypeBoolean
-	case "CounterColumnType":
-		return TypeCounter
-	case "DecimalType":
-		return TypeDecimal
-	case "DoubleType":
-		return TypeDouble
-	case "FloatType":
-		return TypeFloat
-	case "Int32Type":
-		return TypeInt
-	case "ShortType":
-		return TypeSmallInt
-	case "ByteType":
-		return TypeTinyInt
-	case "DateType", "TimestampType":
-		return TypeTimestamp
-	case "UUIDType", "LexicalUUIDType":
-		return TypeUUID
-	case "UTF8Type":
-		return TypeVarchar
-	case "IntegerType":
-		return TypeVarint
-	case "TimeUUIDType":
-		return TypeTimeUUID
-	case "InetAddressType":
-		return TypeInet
-	case "MapType":
-		return TypeMap
-	case "ListType":
-		return TypeList
-	case "SetType":
-		return TypeSet
-	case "TupleType":
-		return TypeTuple
-	default:
-		return TypeCustom
-	}
-}
-
 // error Types
 type ErrType int
 
@@ -565,15 +511,6 @@ const (
 	flagHasMorePages    int = 0x02
 	flagNoMetaData      int = 0x04
 
-	// query flags
-	flagValues                byte = 0x01
-	flagSkipMetaData          byte = 0x02
-	flagPageSize              byte = 0x04
-	flagWithPagingState       byte = 0x08
-	flagWithSerialConsistency byte = 0x10
-	flagDefaultTimestamp      byte = 0x20
-	flagWithNameValues        byte = 0x40
-
 	// header flags
 	flagDefault       byte = 0x00
 	flagCompress      byte = 0x01

packetbeat/protos/memcache/errors.go

@@ -23,16 +23,12 @@ import (
 	"errors"
 )
 
-var errNotImplemented = errors.New("not implemented")
-
 // memcache text parser errors
 var (
 	errParserCaughtInError  = errors.New("memcache parser caught in error loop")
 	errParserUnknownCommand = errors.New("unknown memcache command found")
 	errNoMoreArgument       = errors.New("no more command arguments")
-	errExpectedNumber       = errors.New("expected number value")
 	errExpectedNoReply      = errors.New("expected noreply in argument list")
-	errExpectedCRLF         = errors.New("expected CRLF")
 	errExpectedKeys         = errors.New("message has no keys")
 )
 
@@ -49,11 +45,10 @@ var (
 
 // memcache transaction/message errors
 var (
-	errInvalidMessage             = errors.New("message is invalid")
-	errMixOfBinaryAndText         = errors.New("mix of binary and text in one connection")
-	errResponseUnknownTransaction = errors.New("response from unknown transaction")
-	errExpectedValueForMerge      = errors.New("expected value to merge with")
-	errExpectedStatsForMerge      = errors.New("expected stat response to merge with")
+	errInvalidMessage        = errors.New("message is invalid")
+	errMixOfBinaryAndText    = errors.New("mix of binary and text in one connection")
+	errExpectedValueForMerge = errors.New("expected value to merge with")
+	errExpectedStatsForMerge = errors.New("expected stat response to merge with")
 )
 
 // internal notes to be published with transaction

packetbeat/scripts/mage/config.go

@@ -23,11 +23,6 @@ import (
 	devtools "github.com/elastic/beats/v7/dev-tools/mage"
 )
 
-const (
-	// configTemplateGlob matches Packetbeat protocol config file templates.
-	configTemplateGlob = "protos/*/_meta/config*.yml.tmpl"
-)
-
 var defaultDevice = map[string]string{
 	"darwin":  "en0",
 	"linux":   "any",