httppeer: only advertise partial-pull if capabilities are known We don't need to be advertising client protocol parameters as part of the capabilities request during the handshake because nothing in version 1 of the wire protocol will use this data. i.e. the advertisement is wasteful. Differential Revision: https://phab.mercurial-scm.org/D3241

httppeer: always add x-hg* headers to Vary header Before, we manually updated the Vary header value for each header contributing to it. All X-Hg* headers are reserved for the Mercurial protocol and could have caching implications. So it makes sense to always add these headers to Vary. A test revealed that X-HgArgs-Post wasn't being added to Vary. This is only sent on POST requests. POST requests generally aren't cacheable. However, it is possible if the server sends the appropriate headers. Mercurial shouldn't be sending those headers. But let's not take any chances. Differential Revision: https://phab.mercurial-scm.org/D3240

httppeer: don't accept very old media types (BC) Versions of Mercurial older than 1.0 emitted the text/plain and application/hg-changegroup media types in response to wire protocol commands. Way back in 8760d0c83b9b in 2005, the code validating these media types was added, presumably for backwards compatibility. 0b245edec124 a short time before that commit changed things from text/plain and application/hg-changegroup to application/mercurial-0.1 and application/hg-0.1. 8760d0c83b9b seemed to indicate ("for now") that the BC compatibility was temporary. But that code has lived until this day. It has been more than 10 years and nobody should be running pre 1.0 servers. Pretty much the only risk to this is if there's a server somewhere advertising the old media types or server software is interfering and not letting Mercurial send the proper Content-Type header. I think the chances are rare. The wire protocol docs were created (by me) from reading existing code. So the deletions don't constitute a spec change as much as reflecting the reality of how things have been for years. .. bc:: The HTTP client no longer accepts text/plain and application/hg-changegroup Content-Type values as a valid Mercurial command response. These should only be encountered on pre 1.0 Mercurial servers. Differential Revision: https://phab.mercurial-scm.org/D3239

httppeer: allow opener to be passed to makepeer() This allows us to use makepeer() in `hg debugwireproto`. Differential Revision: https://phab.mercurial-scm.org/D3238

httppeer: perform capabilities request in makepeer() Previously, we constructed an httppeer then always ran _fetchcaps() to issue the capabilities command. We want to issue the capabilities command before constructing a peer instance so we can construct an appropriate peer instance depending on the capabilities result. With the code for making and sending requests moved out of httppeer, it is now possible to send command requests without an httppeer. This commit creates a new function for making the capabilities request and calls it as part of makepeer(). This code should be functionality equivalent to what existed before. Differential Revision: https://phab.mercurial-scm.org/D3237

httppeer: extract common response handling into own function This allows the common redirect detection, content type validation, and decompression wrapping to be usable outside of httppeer instances. Differential Revision: https://phab.mercurial-scm.org/D3236

httppeer: move error handling and response wrapping into sendrequest This is common for all HTTP requests. It should be part of sendrequest(). Differential Revision: https://phab.mercurial-scm.org/D3235

httppeer: extract code for creating a request into own function Some of this feels awkward, such as having to pass in a function to evaluate a capability. And this code is generally pretty difficult to read. I didn't want to perform too much refactoring as part of the code move since it would make review more difficult. Differential Revision: https://phab.mercurial-scm.org/D3234

httppeer: extract code for performing an HTTP request This is generic and doesn't need to live as a method of httppeer. Differential Revision: https://phab.mercurial-scm.org/D3233

httppeer: move requestbuilder defaults into makepeer() argument Upcoming commits will move the initial ?cmd=capabilities handshake request out of httppeer so the handshake can be performed before a peer instance is constructed. In order to do this, we'll need to refactor code for making HTTP requests. The type used to construct HTTP requests is configurable. If we'll be making HTTP requests outside of httppeer, we should be able to use a custom request builder. So move the definition of that type into makepeer(). Extensions can monkeypatch the function and override the argument value. Differential Revision: https://phab.mercurial-scm.org/D3232