Mercurial > hg
view tests/test-repo-compengines.t @ 37048:fc5e261915b9
wireproto: require POST for all HTTPv2 requests
Wire protocol version 1 transfers argument data via request
headers by default. This has historically caused problems because
servers institute limits on the length of individual HTTP headers
as well as the total size of all request headers. Mercurial servers
can advertise the maximum length of an individual header. But
there's no guarantee any intermediate HTTP agents will accept
headers up to that length.
In the existing wire protocol, server operators typically also
key off the HTTP request method to implement authentication.
For example, GET requests translate to read-only requests and
can be allowed. But read-write commands must use POST and require
authentication. This has typically worked because the only wire
protocol commands that use POST modify the repo (e.g. the
"unbundle" command).
There is an experimental feature to enable clients to transmit
argument data via POST request bodies. This is technically a
better and more robust solution. But we can't enable it by default
because of servers assuming POST means write access.
In version 2 of the wire protocol, the permissions of a request
are encoded in the URL. And with it being a new protocol in a new
URL space, we're not constrained by backwards compatibility
requirements.
This commit adopts the technically superior mechanism of using
HTTP request bodies to send argument data by requiring POST for
all commands. Strictly speaking, it may be possible to send
request bodies on GET requests. But my experience is that not all
HTTP stacks support this. POST pretty much always works. Using POST
for read-only operations does sacrifice some RESTful design
purity. But this API cares about practicality, not about being
in Roy T. Fielding's REST ivory tower.
There's a chance we may relax this restriction in the future. But
for now, I want to see how far we can get with a POST only API.
Differential Revision: https://phab.mercurial-scm.org/D2837
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Tue, 13 Mar 2018 11:57:43 -0700 |
parents | 4c0a5a256ae8 |
children | c2c8962a9465 |
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A new repository uses zlib storage, which doesn't need a requirement $ hg init default $ cd default $ cat .hg/requires dotencode fncache generaldelta revlogv1 store $ touch foo $ hg -q commit -A -m 'initial commit with a lot of repeated repeated repeated text to trigger compression' $ hg debugrevlog -c | grep 0x78 0x78 (x) : 1 (100.00%) 0x78 (x) : 110 (100.00%) $ cd .. Unknown compression engine to format.compression aborts $ hg --config experimental.format.compression=unknown init unknown abort: compression engine unknown defined by experimental.format.compression not available (run "hg debuginstall" to list available compression engines) [255] A requirement specifying an unknown compression engine results in bail $ hg init unknownrequirement $ cd unknownrequirement $ echo exp-compression-unknown >> .hg/requires $ hg log abort: repository requires features unknown to this Mercurial: exp-compression-unknown! (see https://mercurial-scm.org/wiki/MissingRequirement for more information) [255] $ cd .. #if zstd $ hg --config experimental.format.compression=zstd init zstd $ cd zstd $ cat .hg/requires dotencode exp-compression-zstd fncache generaldelta revlogv1 store $ touch foo $ hg -q commit -A -m 'initial commit with a lot of repeated repeated repeated text' $ hg debugrevlog -c | grep 0x28 0x28 : 1 (100.00%) 0x28 : 98 (100.00%) $ cd .. Specifying a new format.compression on an existing repo won't introduce data with that engine or a requirement $ cd default $ touch bar $ hg --config experimental.format.compression=zstd -q commit -A -m 'add bar with a lot of repeated repeated repeated text' $ cat .hg/requires dotencode fncache generaldelta revlogv1 store $ hg debugrevlog -c | grep 0x78 0x78 (x) : 2 (100.00%) 0x78 (x) : 199 (100.00%) #endif