From ac5e5a3a12aeee5eed5ca704f1022d1f33144d54 Mon Sep 17 00:00:00 2001
From: Bernd Zeimetz <bernd@bzed.de>
Date: Tue, 20 Feb 2024 10:29:43 +0100
Subject: [PATCH] index.json: Properly escape json strings. (#258)

* Properly escape json strings.

Although most likely not officially supported, we might end up with some
weird metric names in the DB. icinga2 is a good candidate for a source
of broken metrics.
---
 index/index.go      | 10 ++++++----
 index/index_test.go |  5 +++--
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/index/index.go b/index/index.go
index 2e6b5f286..281a187e6 100644
--- a/index/index.go
+++ b/index/index.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"context"
+	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
@@ -81,12 +82,13 @@ func (i *Index) WriteJSON(w http.ResponseWriter) error {
 			continue
 		}
 
-		quote := []byte{'"'}
+		json_b, err := json.Marshal(string(b))
+		if err != nil {
+			return err
+		}
 		jsonParts := [][]byte{
 			nil,
-			quote,
-			b,
-			quote,
+			json_b,
 		}
 		if idx != 0 {
 			jsonParts[0] = []byte{','}
diff --git a/index/index_test.go b/index/index_test.go
index 2f9dfea26..1e37380eb 100644
--- a/index/index_test.go
+++ b/index/index_test.go
@@ -34,15 +34,16 @@ func TestWriteJSONNonleafRows(t *testing.T) {
 		"testing.leaf",
 		"testing.nonleaf.",
 		"testing.leaf.node",
+		"testing.\"broken\".node",
 	}
 	metrics, err := writeRows(rows)
 	if err != nil {
 		t.Fatalf("Error during transform or unmarshal: %s", err)
 	}
-	if len(metrics) != 2 {
+	if len(metrics) != 3 {
 		t.Fatalf("Wrong metrics slice length = %d: %s", len(metrics), metrics)
 	}
-	if metrics[0] != "testing.leaf" || metrics[1] != "testing.leaf.node" {
+	if metrics[0] != "testing.leaf" || metrics[1] != "testing.leaf.node" || metrics[2] != "testing.\"broken\".node" {
 		t.Fatalf("Wrong metrics contents: %s", metrics)
 	}
 }