[ xdebug ] Bind the Xdebug bridge listeners to loopback by mho22 · Pull Request #4486 · WordPress/wordpress-playground

mho22 · 2026-10-21T14:04:27Z

The Xdebug bridge's DBGp listener and CDP WebSocket server listened on all interfaces. Any host on the network could connect to them. Both now bind to 127.0.0.1 by default.

The new dbgpHost option sets the DBGp bind address. cdpHost already existed, but it only changed the printed DevTools URL. It now also sets the CDP bind address.

The CDP server also closes any WebSocket connection whose Origin header is set and does not start with devtools://. Browsers always send Origin, so a web page on the same machine cannot drive the debugger. Clients that send no Origin, such as the DevTools front-end and IDE adapters, still connect.

The exported CDPServer and DbgpSession constructors take the host as the first argument and the port as the second. startBridge keeps its config object, so the Playground CLI and @php-wasm/cli callers do not change.

Testing

Run npm exec -- nx test php-wasm-xdebug-bridge. All 52 tests pass. The tests check the bind host for both listeners, the default and custom hosts in startBridge, and that the CDP server refuses a browser Origin and accepts devtools://.

To check manually, run npx nx dev playground-cli server --xdebug --experimental-devtools. Then run lsof -iTCP:9229 -iTCP:9003 -sTCP:LISTEN and check that both ports show 127.0.0.1.

Summary by CodeRabbit

New Features
- Added configurable host settings for CDP and DBGp debugging endpoints, defaulting to 127.0.0.1.
- Added CDP origin validation, allowing approved developer-tools connections while rejecting unauthorized browser origins.
- Updated the CLI to support and pass through the configured DBGp host.
Documentation
- Updated API and CLI guidance with host configuration options and defaults.
Tests
- Added coverage for host configuration, endpoint defaults, CLI behavior, and CDP origin validation.

The DBGp listener and the CDP WebSocket server listened on all interfaces. Both now bind to 127.0.0.1 by default. The new `dbgpHost` option sets the DBGp host. `cdpHost` now also sets the CDP bind address, not only the printed DevTools URL. The CDP server closes any WebSocket connection whose Origin header is set and does not start with `devtools://`. Breaking change: the `CDPServer` and `DbgpSession` constructors take the host as the first argument and the port as the second.

coderabbitai · 2026-10-21T14:04:36Z

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packages/php-wasm/xdebug-bridge/README.md
packages/php-wasm/xdebug-bridge/src/lib/run-cli.ts
packages/php-wasm/xdebug-bridge/src/test/run-cli.spec.ts

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packages/php-wasm/xdebug-bridge/README.md

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📝 Walkthrough

The Xdebug bridge now accepts configurable CDP and DBGp listener hosts. Both default to 127.0.0.1. CDP connections with a present Origin that does not start with devtools:// are rejected with WebSocket code 1008.

Changes: Bridge listener configuration

Layer / File(s)	Summary
Configure listener hosts `packages/php-wasm/xdebug-bridge/src/lib/start-bridge.ts`, `packages/php-wasm/xdebug-bridge/src/lib/dbgp-session.ts`, `packages/php-wasm/xdebug-bridge/src/lib/run-cli.ts`, `packages/php-wasm/xdebug-bridge/src/test/*`, `packages/php-wasm/xdebug-bridge/README.md`	`StartBridgeConfig` adds `dbgpHost`. `startBridge` passes host and port values to both listeners. The CLI forwards its host to DBGp. Tests and documentation reflect the options and defaults.
Check CDP connection origins `packages/php-wasm/xdebug-bridge/src/lib/cdp-server.ts`, `packages/php-wasm/xdebug-bridge/src/test/cdp-server.spec.ts`, `packages/php-wasm/xdebug-bridge/src/test/mocker.ts`	`CDPServer` binds to its configured host and checks the request Origin. It rejects disallowed origins with code `1008` and reason `Origin not allowed`. Tests cover rejected and accepted origins and verify the server options.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant CLI
  participant startBridge
  participant CDPServer
  participant WebSocketClient
  CLI->>startBridge: Pass dbgpHost
  startBridge->>CDPServer: Configure host and port
  WebSocketClient->>CDPServer: Connect with Origin
  CDPServer->>WebSocketClient: Close with code 1008 for disallowed Origin

Possibly related issues

[ php-wasm ] Follow-up on Xdebug #2315 — Tracks Xdebug Bridge work, including listener host configuration and CDP Origin handling.

Merge Risk: ⚪ Minimal · up to e574b

No actionable merge-blocking risk was identified in the listener configuration or CDP origin changes.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 9 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: binding the Xdebug bridge listeners to loopback by default.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 9 files. (1 skipped: 1 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

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Actionable comments posted: 1

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Inline comments:
Review comments at @packages/php-wasm/xdebug-bridge/src/lib/start-bridge.ts:
- Around line 24-25: Update the standalone CLI’s startBridge invocation to pass
the parsed args.host value as dbgpHost, preserving the documented --host setting
instead of falling back to the default. Locate the call in run-cli.ts and leave
the existing port and other bridge options unchanged.

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Reviewing files that changed from the base of the PR and between 20ea6b2 and c2675dd.

📒 Files selected for processing: 8

packages/php-wasm/xdebug-bridge/README.md
packages/php-wasm/xdebug-bridge/src/lib/cdp-server.ts
packages/php-wasm/xdebug-bridge/src/lib/dbgp-session.ts
packages/php-wasm/xdebug-bridge/src/lib/start-bridge.ts
packages/php-wasm/xdebug-bridge/src/test/cdp-server.spec.ts
packages/php-wasm/xdebug-bridge/src/test/dbgp-session.spec.ts
packages/php-wasm/xdebug-bridge/src/test/mocker.ts
packages/php-wasm/xdebug-bridge/src/test/start-bridge.spec.ts

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The standalone CLI parsed `--host` but did not pass it to `startBridge`, so the DBGp listener always bound to 127.0.0.1. The CLI now passes `--host` as `dbgpHost`. The `--host` default changes from `localhost` to `127.0.0.1` to match the API default.

github-actions Bot added [Focus] Developer Tools [Package][@php-wasm] Xdebug Bridge [Type] Documentation Improvements or additions to documentation labels Oct 21, 2026

mho22 changed the title ~~[PHP-WASM] Bind the Xdebug bridge listeners to loopback~~ [Xdebug] Bind the Xdebug bridge listeners to loopback Oct 21, 2026

mho22 changed the title ~~[Xdebug] Bind the Xdebug bridge listeners to loopback~~ [ xdebug ] Bind the Xdebug bridge listeners to loopback Oct 21, 2026

mho22 mentioned this pull request Oct 21, 2026

[ php-wasm ] Follow-up on Xdebug #2315

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mho22 requested a review from JanJakes October 21, 2026 14:08

mho22 marked this pull request as ready for review October 21, 2026 14:26

coderabbitai Bot reviewed Oct 21, 2026

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Comment thread packages/php-wasm/xdebug-bridge/src/lib/start-bridge.ts

mho22 mentioned this pull request Oct 22, 2026

[ php-wasm ] Reject browser clients in the outbound networking proxy #4492

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[ xdebug ] Bind the Xdebug bridge listeners to loopback - #4486

[ xdebug ] Bind the Xdebug bridge listeners to loopback#4486
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