From 6251b34c1c5c10237cdeda7bbdfa14b2e68caaf8 Mon Sep 17 00:00:00 2001
From: JuanJo Ciarlante <juanjosec@gmail.com>
Date: Wed, 6 Sep 2023 18:28:34 -0300
Subject: [PATCH] use falcopayload.UUID if template rendering produced no value
 (instead of re-generating a random 32char string)

Signed-off-by: JuanJo Ciarlante <juanjosec@gmail.com>
---
 outputs/otlp.go      | 27 +++++++--------------------
 outputs/otlp_test.go |  3 +++
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/outputs/otlp.go b/outputs/otlp.go
index 2ef946626f..764dd09637 100644
--- a/outputs/otlp.go
+++ b/outputs/otlp.go
@@ -3,7 +3,6 @@ package outputs
 import (
 	"bytes"
 	"context"
-	"crypto/rand"
 	"encoding/hex"
 	"fmt"
 	"hash/fnv"
@@ -147,26 +146,14 @@ func generateTraceID(falcopayload types.FalcoPayload, config *types.Configuratio
 	switch traceIDStr {
 	case "":
 	case "<no value>":
-		// Template produced no string :(, generate a random 32 character string
-		traceIDStr, err = randomHex(16)
-		if err != nil {
-			return traceID, "", err
-		}
-	default:
-		// Hash the returned template- rendered string to generate a 32 character traceID
-		hash := fnv.New128a()
-		hash.Write([]byte(traceIDStr))
-		digest := hash.Sum(nil)
-		traceIDStr = hex.EncodeToString(digest[:])
+		// Template produced no string, derive the traceID from the payload UUID
+		traceIDStr = falcopayload.UUID
 	}
+	// Hash the returned template- rendered string to generate a 32 character traceID
+	hash := fnv.New128a()
+	hash.Write([]byte(traceIDStr))
+	digest := hash.Sum(nil)
+	traceIDStr = hex.EncodeToString(digest[:])
 	traceID, err = trace.TraceIDFromHex(traceIDStr)
 	return traceID, tplStr, err
 }
-
-func randomHex(n int) (string, error) {
-	bytes := make([]byte, n)
-	if _, err := rand.Read(bytes); err != nil {
-		return "", err
-	}
-	return hex.EncodeToString(bytes), nil
-}
diff --git a/outputs/otlp_test.go b/outputs/otlp_test.go
index 565b2cab7b..390a1e80a7 100644
--- a/outputs/otlp_test.go
+++ b/outputs/otlp_test.go
@@ -195,6 +195,7 @@ func TestOtlpNewTrace(t *testing.T) {
 
 		}
 		// Test newTrace()
+		c.fp.UUID = uuid.New().String()
 		span := client.newTrace(c.fp)
 		require.NotNil(t, span)
 
@@ -211,6 +212,8 @@ func TestOtlpNewTrace(t *testing.T) {
 		}
 
 		// Verify traceID
+		// ~hack: to pass c.expectedRandom==true case, recreate fp.UUID as generateTraceID() derives from it
+		c.fp.UUID = uuid.New().String()
 		traceID, templateStr, err := generateTraceID(c.fp, &c.config)
 		require.Nil(t, err, c.msg)
 		// Always generate a traceID (unless errored)