Loki: Fix wrongly escaped label values when using LabelFilter (#59812)

* change backticks to quotes

* add unescaping to `addFilterAsLabelFilter`

* fix removal of wrong quotes

* change unescape order

public/app/plugins/datasource/loki/languageUtils.test.ts

@@ -1,4 +1,4 @@
-import { isBytesString } from './languageUtils';
+import { escapeLabelValueInExactSelector, isBytesString, unescapeLabelValue } from './languageUtils';
 
 describe('isBytesString', () => {
   it('correctly matches bytes string with integers', () => {
@@ -18,3 +18,27 @@ describe('isBytesString', () => {
     expect(isBytesString('1.234')).toBe(false);
   });
 });
+
+describe('escapeLabelValueInExactSelector', () => {
+  it.each`
+    value                      | escapedValue
+    ${'nothing to escape'}     | ${'nothing to escape'}
+    ${'escape quote: "'}       | ${'escape quote: \\"'}
+    ${'escape newline: \nend'} | ${'escape newline: \\nend'}
+    ${'escape slash: \\'}      | ${'escape slash: \\\\'}
+  `('when called with $value', ({ value, escapedValue }) => {
+    expect(escapeLabelValueInExactSelector(value)).toEqual(escapedValue);
+  });
+});
+
+describe('unescapeLabelValueInExactSelector', () => {
+  it.each`
+    value                       | unescapedValue
+    ${'nothing to unescape'}    | ${'nothing to unescape'}
+    ${'escape quote: \\"'}      | ${'escape quote: "'}
+    ${'escape newline: \\nend'} | ${'escape newline: \nend'}
+    ${'escape slash: \\\\'}     | ${'escape slash: \\'}
+  `('when called with $value', ({ value, unescapedValue }) => {
+    expect(unescapeLabelValue(value)).toEqual(unescapedValue);
+  });
+});

public/app/plugins/datasource/loki/languageUtils.ts

@@ -35,6 +35,10 @@ export function escapeLabelValueInExactSelector(labelValue: string): string {
   return labelValue.replace(/\\/g, '\\\\').replace(/\n/g, '\\n').replace(/"/g, '\\"');
 }
 
+export function unescapeLabelValue(labelValue: string): string {
+  return labelValue.replace(/\\n/g, '\n').replace(/\\"/g, '"').replace(/\\\\/g, '\\');
+}
+
 export function escapeLabelValueInRegexSelector(labelValue: string): string {
   return escapeLabelValueInExactSelector(escapeLokiRegexp(labelValue));
 }

public/app/plugins/datasource/loki/modifyQuery.test.ts

@@ -44,6 +44,14 @@ describe('addLabelToQuery()', () => {
     ${'{} | logfmt | x="y"'}                                                                                                          | ${'query without stream selector and with parser and label filter'}            | ${'bar'} | ${'='}   | ${'baz'}       | ${'{bar="baz"}| logfmt | x="y"'}
     ${'sum(rate({x="y"} [5m])) + sum(rate({} | logfmt [5m]))'}                                                                        | ${'metric query with 1 empty and 1 not empty stream selector with parser'}     | ${'bar'} | ${'='}   | ${'baz'}       | ${'sum(rate({x="y", bar="baz"} [5m])) + sum(rate({bar="baz"}| logfmt [5m]))'}
     ${'sum(rate({x="y"} | logfmt [5m])) + sum(rate({} [5m]))'}                                                                        | ${'metric query with 1 non-empty and 1 not empty stream selector with parser'} | ${'bar'} | ${'='}   | ${'baz'}       | ${'sum(rate({x="y", bar="baz"} | logfmt [5m])) + sum(rate({bar="baz"}[5m]))'}
+    ${'{x="yy"}'}                                                                                                                     | ${'simple query with escaped value'}                                           | ${'bar'} | ${'='}   | ${'"baz"'}     | ${'{x="yy", bar=""baz""}'}
+    ${'{x="yy"}'}                                                                                                                     | ${'simple query with escaped value'}                                           | ${'bar'} | ${'='}   | ${'\\"baz\\"'} | ${'{x="yy", bar="\\"baz\\""}'}
+    ${'{x="yy"}'}                                                                                                                     | ${'simple query with an other escaped value'}                                  | ${'bar'} | ${'='}   | ${'baz\\\\'}   | ${'{x="yy", bar="baz\\\\"}'}
+    ${'{x="yy"}'}                                                                                                                     | ${'simple query with escaped value and regex operator'}                        | ${'bar'} | ${'~='}  | ${'baz\\\\'}   | ${'{x="yy", bar~="baz\\\\"}'}
+    ${'{foo="bar"} | logfmt'}                                                                                                         | ${'query with parser with escaped value'}                                      | ${'bar'} | ${'='}   | ${'\\"baz\\"'} | ${'{foo="bar"} | logfmt | bar=`"baz"`'}
+    ${'{foo="bar"} | logfmt'}                                                                                                         | ${'query with parser with an other escaped value'}                             | ${'bar'} | ${'='}   | ${'baz\\\\'}   | ${'{foo="bar"} | logfmt | bar=`baz\\`'}
+    ${'{foo="bar"} | logfmt'}                                                                                                         | ${'query with parser with escaped value and regex operator'}                   | ${'bar'} | ${'~='}  | ${'\\"baz\\"'} | ${'{foo="bar"} | logfmt | bar~=`"baz"`'}
+    ${'{foo="bar"} | logfmt'}                                                                                                         | ${'query with parser with escaped value and regex operator'}                   | ${'bar'} | ${'~='}  | ${'\\"baz\\"'} | ${'{foo="bar"} | logfmt | bar~=`"baz"`'}
   `(
     'should add label to query:  $query, description: $description',
     ({ query, description, label, operator, value, expectedResult }) => {

public/app/plugins/datasource/loki/modifyQuery.ts

@@ -18,6 +18,7 @@ import {
 
 import { QueryBuilderLabelFilter } from '../prometheus/querybuilder/shared/types';
 
+import { unescapeLabelValue } from './languageUtils';
 import { LokiQueryModeller } from './querybuilder/LokiQueryModeller';
 import { buildVisualQueryFromString } from './querybuilder/parsing';
 
@@ -329,7 +330,9 @@ function addFilterAsLabelFilter(
     const start = query.substring(prev, match.to);
     const end = isLast ? query.substring(match.to) : '';
 
-    const labelFilter = ` | ${filter.label}${filter.op}\`${filter.value}\``;
+    // we now unescape all escaped values again, because we are using backticks which can handle those cases.
+    // we also don't care about the operator here, because we need to unescape for both, regex and equal.
+    const labelFilter = ` | ${filter.label}${filter.op}\`${unescapeLabelValue(filter.value)}\``;
     newQuery += start + labelFilter + end;
     prev = match.to;
   }

public/app/plugins/datasource/loki/querybuilder/parsing.test.ts

@@ -571,6 +571,21 @@ describe('buildVisualQueryFromString', () => {
       })
     );
   });
+
+  it('parses simple query with quotes in label value', () => {
+    expect(buildVisualQueryFromString('{app="\\"frontend\\""}')).toEqual(
+      noErrors({
+        labels: [
+          {
+            op: '=',
+            value: '\\"frontend\\"',
+            label: 'app',
+          },
+        ],
+        operations: [],
+      })
+    );
+  });
 });
 
 function noErrors(query: LokiVisualQuery) {

public/app/plugins/datasource/loki/querybuilder/parsing.ts

@@ -212,7 +212,9 @@ function getLabel(expr: string, node: SyntaxNode): QueryBuilderLabelFilter {
   const labelNode = node.getChild(Identifier);
   const label = getString(expr, labelNode);
   const op = getString(expr, labelNode!.nextSibling);
-  const value = getString(expr, node.getChild(String)).replace(/"/g, '');
+  let value = getString(expr, node.getChild(String));
+  // `value` is wrapped in double quotes, so we need to remove them. As a value can contain double quotes, we can't use RegEx here.
+  value = value.substring(1, value.length - 1);
 
   return {
     label,