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Differential D3239

httppeer: don't accept very old media types (BC)
ClosedPublic

Authored by indygreg on Apr 10 2018, 9:28 PM.

Details

Reviewers
durin42
Group Reviewers
hg-reviewers
Commits
rHG301a1d2e8016: httppeer: don't accept very old media types (BC)
Summary

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.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

indygreg created this revision.Apr 10 2018, 9:28 PM
durin42 accepted this revision.Apr 11 2018, 12:49 PM
This revision is now accepted and ready to land.Apr 11 2018, 12:49 PM
Closed by commit rHG301a1d2e8016: httppeer: don't accept very old media types (BC) (authored by indygreg). · Explain WhyApr 11 2018, 1:01 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

Diff 8000

mercurial/help/internals/wireprotocol.txt

format. e.g. ``zlib``. The remaining bytes are compressed according to that format. e.g. ``zlib``. The remaining bytes are compressed according to that
compression format. The decompressed data behaves the same as with compression format. The decompressed data behaves the same as with
``application/mercurial-0.1``. ``application/mercurial-0.1``.
The ``application/hg-error`` media type indicates a generic error occurred. The ``application/hg-error`` media type indicates a generic error occurred.
The content of the HTTP response body typically holds text describing the The content of the HTTP response body typically holds text describing the
error. error.
The ``application/hg-changegroup`` media type indicates a changegroup response
type.
Clients also accept the ``text/plain`` media type. All other media
types should cause the client to error.
Behavior of media types is further described in the ``Content Negotiation`` Behavior of media types is further described in the ``Content Negotiation``
section below. section below.
Clients should issue a ``User-Agent`` request header that identifies the client. Clients should issue a ``User-Agent`` request header that identifies the client.
The server should not use the ``User-Agent`` for feature detection. The server should not use the ``User-Agent`` for feature detection.
A command returning a ``string`` response issues a A command returning a ``string`` response issues a
``application/mercurial-0.*`` media type and the HTTP response body contains ``application/mercurial-0.*`` media type and the HTTP response body contains

mercurial/httppeer.py

try: try:
proto = pycompat.bytesurl(resp.getheader(r'content-type', r'')) proto = pycompat.bytesurl(resp.getheader(r'content-type', r''))
except AttributeError: except AttributeError:
proto = pycompat.bytesurl(resp.headers.get(r'content-type', r'')) proto = pycompat.bytesurl(resp.headers.get(r'content-type', r''))
safeurl = util.hidepassword(baseurl) safeurl = util.hidepassword(baseurl)
if proto.startswith('application/hg-error'): if proto.startswith('application/hg-error'):
raise error.OutOfBandError(resp.read()) raise error.OutOfBandError(resp.read())
# accept old "text/plain" and "application/hg-changegroup" for now
if not (proto.startswith('application/mercurial-') or # Pre 1.0 versions of Mercurial used text/plain and
(proto.startswith('text/plain') # application/hg-changegroup. We don't support such old servers.
and not resp.headers.get('content-length')) or if not proto.startswith('application/mercurial-'):
proto.startswith('application/hg-changegroup')):
ui.debug("requested URL: '%s'\n" % util.hidepassword(requrl)) ui.debug("requested URL: '%s'\n" % util.hidepassword(requrl))
raise error.RepoError( raise error.RepoError(
_("'%s' does not appear to be an hg repository:\n" _("'%s' does not appear to be an hg repository:\n"
"---%%<--- (%s)\n%s\n---%%<---\n") "---%%<--- (%s)\n%s\n---%%<---\n")
% (safeurl, proto or 'no content-type', resp.read(1024))) % (safeurl, proto or 'no content-type', resp.read(1024)))
if proto.startswith('application/mercurial-'):
try: try:
version = proto.split('-', 1)[1] version = proto.split('-', 1)[1]
version_info = tuple([int(n) for n in version.split('.')]) version_info = tuple([int(n) for n in version.split('.')])
except ValueError: except ValueError:
raise error.RepoError(_("'%s' sent a broken Content-Type " raise error.RepoError(_("'%s' sent a broken Content-Type "
"header (%s)") % (safeurl, proto)) "header (%s)") % (safeurl, proto))
# TODO consider switching to a decompression reader that uses # TODO consider switching to a decompression reader that uses
# generators. # generators.
if version_info == (0, 1): if version_info == (0, 1):
if compressible: if compressible:
resp = util.compengines['zlib'].decompressorreader(resp) resp = util.compengines['zlib'].decompressorreader(resp)
return respurl, resp
elif version_info == (0, 2): elif version_info == (0, 2):
# application/mercurial-0.2 always identifies the compression # application/mercurial-0.2 always identifies the compression
# engine in the payload header. # engine in the payload header.
elen = struct.unpack('B', resp.read(1))[0] elen = struct.unpack('B', resp.read(1))[0]
ename = resp.read(elen) ename = resp.read(elen)
engine = util.compengines.forwiretype(ename) engine = util.compengines.forwiretype(ename)
return respurl, engine.decompressorreader(resp)
resp = engine.decompressorreader(resp)
else: else:
raise error.RepoError(_("'%s' uses newer protocol %s") % raise error.RepoError(_("'%s' uses newer protocol %s") %
(safeurl, version)) (safeurl, version))
if compressible:
resp = util.compengines['zlib'].decompressorreader(resp)
return respurl, resp return respurl, resp
class httppeer(wireproto.wirepeer): class httppeer(wireproto.wirepeer):
def __init__(self, ui, path, url, opener, requestbuilder, caps): def __init__(self, ui, path, url, opener, requestbuilder, caps):
self.ui = ui self.ui = ui
self._path = path self._path = path
self._url = url self._url = url
self._caps = caps self._caps = caps