feat: add proxyMode option

[pqnet]

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[pqnet]

fixes #168

[Fdawgs]

I think this, alongside #165, should be rewritten so that there is a simple boolean proxy option that, when enabled, supports the Proxy-Authorization header and sets the correct error response code.

This way we're enforcing adherence to specifications.

[pqnet]

I think this, alongside #165, should be rewritten so that there is a simple boolean proxy option that, when enabled, supports the Proxy-Authorization header and sets the correct error response code.

This way we're enforcing adherence to specifications.

I agree. Initially I thought to align with the setting for the Authorization header name, and allow customization of these other parameters as well, but then I had a change of mind, in particular since both the headers and the status code need to be changed as well. The PR was already merged and shipped though, so I continued in the same direction.

I can take care of implementing the changes + tests for this, though I'd need to clarify a couple things:

• Support customization of authorize header #165 has already been shipped in 6.1.0, is it fine to revert the change and go in another direction although it would technically break compatibility?
• would a proxyMode global option switching to 407/Proxy-Authenticate/Proxy-Authorization (if no header global option overrides it) be the right direction? Or we keep it an authenticate only option, requiring to manually set the header option to be compliant with the standard?

[Fdawgs]

I think this, alongside #165, should be rewritten so that there is a simple boolean proxy option that, when enabled, supports the Proxy-Authorization header and sets the correct error response code.
This way we're enforcing adherence to specifications.

I agree. Initially I thought to align with the setting for the Authorization header name, and allow customization of these other parameters as well, but then I had a change of mind, in particular since both the headers and the status code need to be changed as well. The PR was already merged and shipped though, so I continued in the same direction.

I can take care of implementing the changes + tests for this, though I'd need to clarify a couple things:

* [Support customization of authorize header #165](https://github.com/fastify/fastify-basic-auth/pull/165) has already been shipped in 6.1.0, is it fine to revert the change and go in another direction although it would technically break compatibility?

* would a `proxyMode` global option switching to `407`/`Proxy-Authenticate`/`Proxy-Authorization` (if no `header` global option overrides it) be the right direction? Or we keep it an `authenticate` only option, requiring to manually set the `header` option to be compliant with the standard?

Thanks @pqnet, we'd just need to do a major release to switch to this proxyMode direction, no biggy. :)

@fastify/plugins wdyt?

[pqnet]

@Fdawgs I have updated this PR to implement the proxyMode option rather than allowing any custom http code, for now without stripping the authenticate.header option support to maintain backward compatibility. Once you discuss between maintainers and decide that removing it is the best option it is as simple as changing one line of code, one of typings, and remove the two failing test cases and one paragraph in the docs referring to that. Most of the existing code for the custom authorization header is still required to support proxyMode

[Fdawgs]

This is perfect, thanks @pqnet. Will take a proper look this evening.

[mcollina]

lgtm

[Copilot]

Pull Request Overview

This PR introduces a new option, proxyMode, to enable HTTP proxy authentication instead of resource authentication. Key changes include:

• Adding proxyMode support in type definitions and tests.
• Updating the main plugin logic in index.js to adjust header names, status codes, and error handling when proxyMode is enabled.
• Enhancing the documentation in README.md to reflect the new proxyMode functionality.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

File	Description
types/index.test-d.ts	Adds tests for the new proxyMode option
test/index.test.js	Implements tests validating proxy authentication logic
index.js	Updates authentication logic to support proxyMode
README.md	Updates documentation for proxyMode option