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

wireproto: move version 2 command handlers to wireprotov2server This is relatively straightforward. As part of this, we introduced a local @wireprotocommand that wraps the main one and defines a v2 only policy by default. Because the hacky HTTPv2 peer isn't using capabilities response yet, we had to move some code around to force import of wireprotov2server so commands are registered. This is super hacky. But this code will go away once the HTTPv2 peer is using the capabilities response to derive permissions. Differential Revision: https://phab.mercurial-scm.org/D3231

wireproto: extract HTTP version 2 code to own module wireprotoserver has generic and version 1 server code. The wireproto module also has both version 1 and version 2 command implementations. Upcoming work I want to do will make it difficult for this code to live in the current locations. Plus, it kind of makes sense for the version 2 code to live in an isolated module. This commit copies the HTTPv2 bits from wireprotoserver into a new module. We do it as a file copy to preserve history. A future commit will be copying wire protocol commands into this module as well. But there is little history of that code, so it makes sense to take history for wireprotoserver. Differential Revision: https://phab.mercurial-scm.org/D3230

wireproto: client reactor support for receiving frames We can now feed received frames into the client reactor and it will validate their sanity, dispatch them appropriately. The hacky HTTP peer has been updated to use the new code. No existing tests changed, somewhat proving the code works as expected. Rudimentary unit tests for the new functionality have been implemented. Differential Revision: https://phab.mercurial-scm.org/D3224

wireproto: introduce a reactor for client-side state We have a nice state machine of sorts for reacting to server-side events. Now it is time to implement the client equivalent. We introduce a "clientreactor." It allows callers to request that commands be issued. It has multiple modes of operation to reflect what the underlying transport supports. e.g. for SSH, we can perform wire sends immediately but for HTTP we need to buffer sends until all command requests are received. In addition, SSH allows sending multiple requests as long as the connection is open. But HTTP/1.1 only allows sending request data once. For SSH, we'll have one reactor per connection. For HTTP, we'll have one reactor per HTTP request. But because code that calls wire protocol commands should not be aware of how the underlying transport works, this will all be abstracted away by the peer interface. Our crude HTTP peer has been updated to use the reactor instead of formulating frames directly. No behavior should have changed here and tests seem to confirm that. Basic unit tests for the reactor behavior have been added. Differential Revision: https://phab.mercurial-scm.org/D3223

tests: extract wire protocol framing tests to own file I was lazy when I put these in test-wireproto-serverreactor.py. Let's do it properly. Differential Revision: https://phab.mercurial-scm.org/D3222

wireproto: disallow commands handlers for multiple transport versions I think it will be more trouble than it is worth to code version 1 and version 2 command handlers to the same interface. It will feel awkward to shoehorn functionality into e.g. the version 1 protocol handler interface. This would likely constrain the ability for version 2 to evolve. Previous commits introduced a clean separation between command handlers for version 1 and version 2 transports. This commit reinforces that separation by dropping support for having a single command handler service both version 1 and version 2 transports. Differential Revision: https://phab.mercurial-scm.org/D3208

wireproto: make @wireprotocommand version 1 only by default For backwards compatibility reasons. We want extension provided commands to opt in to version 2 rather than get inherited automatically. This will facilitate a clean break between the protocols. As part of this, we duplicate some commands used in tests so there are different command handlers per transport. Differential Revision: https://phab.mercurial-scm.org/D3207