fix: prevent excessive scanning during JWT redaction

<!-- coderabbit-ai-generated:v1 -->

Author: coderabbitai[bot]

packages/devtools/src/__tests__/jwt-redaction.test.ts

@@ -0,0 +1,59 @@
+import { describe, expect, it } from 'vitest';
+import { redactMessage as redactLogMessage } from '../analog-server-log.ts';
+import { redactJwt, redactMessage } from '../forms-privacy.ts';
+import { redactText } from '../text-redact.ts';
+import { toPluginsPage } from '../rpc/plugins-register.ts';
+import { resolvePangularConfig } from '../config.ts';
+
+const token = 'eyJabcd.payload.signature';
+
+describe('JWT redaction', () => {
+  it('keeps the original matching rules for signed, unsigned and adjacent tokens', () => {
+    const samples = [
+      `before ${token} after`,
+      'eyJabcd.efgh.',
+      `${token},eyJ1234.5678.-_9`,
+      'eyJabc.efgh.signature eyJabcd.efg.signature',
+      `eyJbad.${token}`,
+      `prefix${token}!`,
+      'eyJabcd.efgh.é',
+      'eyJeyJeyJeyJ.nope',
+    ];
+    for (const sample of samples) {
+      expect(redactJwt(sample)).toBe(
+        sample.replace(/eyJ[\w-]{4,}\.[\w-]{4,}\.[\w-]*/g, '[redacted]'),
+      );
+    }
+    for (const redact of [redactMessage, redactText, redactLogMessage]) {
+      expect(redact(`before ${token} after`)).toBe('before [redacted] after');
+      expect(redact('eyJabcd.efgh.')).toBe('[redacted]');
+    }
+  });
+
+  it('handles many overlapping candidates and still masks a later token', () => {
+    const input = `${'eyJ'.repeat(100_000)}!${token}`;
+    expect(redactJwt(input)).toBe(`${'eyJ'.repeat(100_000)}![redacted]`);
+  });
+
+  it('processes an adversarial plugin view and masks its token before clipping', () => {
+    const page = toPluginsPage(
+      {
+        pageId: 'tab1',
+        plugins: [
+          {
+            id: 'test',
+            view: {
+              sections: [{ kind: 'text', title: 'Test', text: `${token}!${'eyJ'.repeat(20_000)}` }],
+            },
+          },
+        ],
+      },
+      resolvePangularConfig(),
+    );
+    expect(page?.plugins[0].view?.sections).toHaveLength(1);
+    expect(page?.plugins[0].view?.sections[0]).toMatchObject({
+      text: expect.stringMatching(/^\[redacted\]!/),
+    });
+    expect(JSON.stringify(page)).not.toContain(token);
+  });
+});

packages/devtools/src/analog-server-log.ts

@@ -1,6 +1,6 @@
 import type { IncomingMessage, ServerResponse } from 'node:http';
 import { redactCredentials } from './credential-redact.ts';
-import { JWT, isRedactedKey } from './forms-privacy.ts';
+import { isRedactedKey, redactJwt } from './forms-privacy.ts';
 import { redactJsonText } from './json-text-redact.ts';
 
 const BEARER = /\bBearer\s+[\w.~+/=-]+/gi;
@@ -19,8 +19,7 @@ function queryKey(key: string): string {
 }
 
 export function redactMessage(text: string): string {
-  return redactCredentials(text, '[redacted]')
-    .replace(JWT, '[redacted]')
+  return redactJwt(redactCredentials(text, '[redacted]'))
     .replace(BEARER, 'Bearer [redacted]')
     .replace(QUERY_PAIR, (whole, sep: string, key: string) => {
       const name = queryKey(key);

packages/devtools/src/forms-privacy.ts

@@ -122,8 +122,40 @@ const SECRET_AUTOCOMPLETE = /password|one-time-code|cc-/i;
 /** Elements whose content never leaves the page (also blacked out in component screenshots). */
 export const MASK_MARKERS = '.sentry-mask, .rr-mask, [data-private], [data-pangular="mask"]';
 export const UNMASK_MARKER = '[data-pangular="unmask"]';
-/** A JWT, including an unsigned (`alg: none`) one with an empty signature. */
-export const JWT = /eyJ[\w-]{4,}\.[\w-]{4,}\.[\w-]*/g;
+function jwtCharacter(code: number): boolean {
+  return (
+    (code >= 65 && code <= 90) ||
+    (code >= 97 && code <= 122) ||
+    (code >= 48 && code <= 57) ||
+    code === 95 ||
+    code === 45
+  );
+}
+
+/** Masks JWTs, including unsigned ones, without retrying every prefix in a segment. */
+export function redactJwt(text: string): string {
+  let search = 0;
+  let last = 0;
+  const parts: string[] = [];
+  while (search < text.length) {
+    const start = text.indexOf('eyJ', search);
+    if (start < 0) break;
+    let headerEnd = start + 3;
+    while (jwtCharacter(text.charCodeAt(headerEnd))) headerEnd++;
+    // Later prefixes in this segment have the same end and a shorter header.
+    search = headerEnd;
+    if (headerEnd - start < 7 || text[headerEnd] !== '.') continue;
+    let payloadEnd = headerEnd + 1;
+    while (jwtCharacter(text.charCodeAt(payloadEnd))) payloadEnd++;
+    if (payloadEnd - headerEnd - 1 < 4 || text[payloadEnd] !== '.') continue;
+    let end = payloadEnd + 1;
+    while (jwtCharacter(text.charCodeAt(end))) end++;
+    parts.push(text.slice(last, start), REDACTED);
+    last = end;
+    search = end;
+  }
+  return parts.length ? parts.join('') + text.slice(last) : text;
+}
 const BEARER = /\bBearer\s+[\w.~+/=-]+/gi;
 
 interface PrivacyConfig {
@@ -300,9 +332,7 @@ export function longestFirst(secrets: Iterable<string>): string[] {
 
 /** `redactMessage` with secrets `longestFirst` already prepared, for many texts in a row. */
 export function redactMessageWith(text: string, ordered: readonly string[]): string {
-  let out = redactCredentials(text, REDACTED)
-    .replace(JWT, REDACTED)
-    .replace(BEARER, `Bearer ${REDACTED}`);
+  let out = redactJwt(redactCredentials(text, REDACTED)).replace(BEARER, `Bearer ${REDACTED}`);
   for (const secret of ordered) out = out.split(secret).join(REDACTED);
   return out;
 }

packages/devtools/src/text-redact.ts

@@ -1,5 +1,5 @@
 import { redactCredentials } from './credential-redact.ts';
-import { JWT, REDACTED, isRedactedKey, wordsOf } from './forms-privacy.ts';
+import { REDACTED, isRedactedKey, redactJwt, wordsOf } from './forms-privacy.ts';
 
 /**
  * Masking for free text and URLs, shared by `serialize`, the router collector
@@ -193,11 +193,11 @@ export function redactText(
       if (isSecretKey(decode(key))) return `${sep}${key}${eq}${REDACTED}`;
       return nested(match, `${sep}${key}${eq}`, value, secrets, mode, depth);
     });
-    out = out.replace(JWT, REDACTED).replace(BEARER, `Bearer ${REDACTED}`);
+    out = redactJwt(out).replace(BEARER, `Bearer ${REDACTED}`);
     out = out.replace(LONG_TOKEN, (token) => (isOpaqueToken(token) ? REDACTED : token));
   } else {
     // Bearer tokens and JWTs first, so `token: Bearer abc` can't keep `abc` once `Bearer` is hidden.
-    out = out.replace(JWT, REDACTED).replace(BEARER, `Bearer ${REDACTED}`);
+    out = redactJwt(out).replace(BEARER, `Bearer ${REDACTED}`);
     const pair = (
       match: string,
       quote: string,