fix: correct redirect count increment in fetchJson

[KevinZhao]

Fixes #24893

Summary

fetchJson in github_fetch.ts had three issues in its redirect handling:

1. Unbounded redirects: Used post-increment (redirectCount++) which always passes 0 to the recursive call, so the redirect limit never triggers
2. Relative redirect URLs: Passed res.headers.location directly without resolving against the current URL — relative Location headers would fail
3. Socket leak: The redirect response stream was not consumed, which can cause socket exhaustion

The sibling function downloadFile in github.ts:546 already handles the redirect count correctly with redirectCount + 1.

Changes

• Replace redirectCount++ with redirectCount + 1 to correctly enforce the redirect limit
• Use new URL(res.headers.location, url).toString() to resolve relative Location headers
• Add res.resume() to drain the redirect response body and release the socket

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a bug in the redirect handling logic within the fetch utility. By correcting how the redirect counter is passed during recursive calls, it ensures that the redirect limit is properly enforced, preventing potential infinite redirect loops.

Highlights

• Redirect Logic Correction: Replaced the post-increment operator with an addition expression in the recursive call to ensure the redirect count is correctly tracked.

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[gemini-code-assist]

Code Review

This pull request fixes a bug in the fetchJson function where the redirect count was not being correctly incremented during recursive calls. The review feedback highlights a critical security vulnerability where sensitive authorization tokens could be leaked to external domains during redirects. Additionally, the reviewer noted functional issues regarding the handling of relative redirect URLs and potential resource leaks from unconsumed response streams, providing a code suggestion to address these concerns.

[gemini-code-assist]

The fetchJson function's redirect logic has several issues.

Firstly, a critical security vulnerability exists: the Authorization header (containing the GITHUB_TOKEN) is unconditionally attached to all requests, including redirects. If a redirect points to a different domain (e.g., a third-party storage provider or a malicious site), the sensitive GITHUB_TOKEN will be leaked. It's crucial to verify that the redirect URL's hostname matches the original URL's hostname before including the token in subsequent requests.

Additionally, there are two functional issues:

1. Relative Redirects: The Location header can contain a relative path (e.g., /path/to/resource). Passing this directly to fetchJson will cause https.get to fail. The redirect URL should be resolved against the current url using the URL constructor.
2. Resource Leak: When handling a redirect, the response stream (res) must be consumed or resumed to ensure the underlying socket is properly released and returned to the pool, preventing socket exhaustion or memory leaks.

Suggested change

	fetchJson<T>(res.headers.location, redirectCount + 1)
	res.resume();
	fetchJson<T>(new URL(res.headers.location, url).toString(), redirectCount + 1)