[Filebeat] adding base64encode func to value template

CHANGELOG.next.asciidoc

@@ -772,6 +772,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Update `tags` and `threatintel.indicator.provider` fields in `threatintel.anomali` ingest pipeline {issue}24746[24746] {pull}27141[27141]
 - Move AWS module and filesets to GA. {pull}27428[27428]
 - update ecs.version to ECS 1.11.0. {pull}27107[27107]
+- Add base64 Encode functionality to httpjson input. {pull}27681[27681]
 
 *Heartbeat*
 

x-pack/filebeat/docs/inputs/input-httpjson.asciidoc

@@ -204,6 +204,7 @@ Some built-in helper functions are provided to work with the input state inside
 - `mul`: multiplies two integers.
 - `div`: does the integer division of two integer values.
 - `hmac`: calculates the hmac signature of a list of strings concatenated together. Supports sha1 or sha256. Example `[[hmac "sha256" "secret" "string1" "string2" (formatDate (now) "RFC1123")]]`
+- `base64Encode`: Joins and base64 encodes all supplied strings. Example `[[base64Encode "string1" "string2"]]`
 
 In addition to the provided functions, any of the native functions for https://golang.org/pkg/time/#Time[`time.Time`], https://golang.org/pkg/net/http/#Header[`http.Header`], and https://golang.org/pkg/net/url/#Values[`url.Values`] types can be used on the corresponding objects. Examples: `[[(now).Day]]`, `[[.last_response.header.Get "key"]]`
 

x-pack/filebeat/input/httpjson/internal/v2/value_tpl.go

@@ -9,6 +9,7 @@ import (
  "crypto/hmac"
  "crypto/sha1"
  "crypto/sha256"
+ "encoding/base64"
  "encoding/hex"
  "errors"
  "hash"
@@ -54,6 +55,7 @@ func (t *valueTpl) Unpack(in string) error {
  "mul": mul,
  "div": div,
  "hmac": hmacString,
+ "base64Encode": base64Encode,
  }).
  Delims(leftDelim, rightDelim).
  Parse(in)
@@ -243,6 +245,15 @@ func div(a, b int64) int64 {
  return a / b
 }
 
+func base64Encode(values ...string) string {
+ data := strings.Join(values[:], "")
+ if data == "" {
+ return ""
+ }
+
+ return base64.StdEncoding.EncodeToString([]byte(data))
+}
+
 func hmacString(hmacType string, hmacKey string, values ...string) string {
  data := strings.Join(values[:], "")
  if data == "" {

x-pack/filebeat/input/httpjson/internal/v2/value_tpl_test.go

@@ -276,6 +276,21 @@ func TestValueTpl(t *testing.T) {
  expectedVal: "",
  expectedError: errEmptyTemplateResult.Error(),
  },
+ {
+ name: "func base64Encode 2 strings",
+ value: `[[base64Encode "string1" "string2"]]`,
+ paramCtx: emptyTransformContext(),
+ paramTr: transformable{},
+ expectedVal: "c3RyaW5nMXN0cmluZzI=",
+ },
+ {
+ name: "func base64Encode no value",
+ value: `[[base64Encode ""]]`,
+ paramCtx: emptyTransformContext(),
+ paramTr: transformable{},
+ expectedVal: "",
+ expectedError: errEmptyTemplateResult.Error(),
+ },
  }
 
  for _, tc := range cases {