This is an archive of the discontinued Mercurial Phabricator instance.

Differential D2982

wireproto: separate commands tables for version 1 and 2 commands
ClosedPublic

Authored by indygreg on Mar 30 2018, 5:16 PM.

Details

Reviewers
durin42
Group Reviewers
hg-reviewers
Commits
rHG45b39c69fae0: wireproto: separate commands tables for version 1 and 2 commands
Summary

We can't easily reuse existing command handlers for version 2
commands because the response types will be different. e.g. many
commands return nodes encoded as hex. Our new wire protocol is
binary safe, so we'll wish to encode nodes as binary.

We /could/ teach each command handler to look at the protocol
handler and change behavior based on the version in use. However,
this would make logic a bit unwieldy over time and would make
it harder to design a unified protocol handler interface. I think
it's better to create a clean break between version 1 and version 2
of commands on the server.

What I imagine happening is we will have separate @wireprotocommand
functions for each protocol generation. Those functions will parse the
request, dispatch to a common function to process it, then generate
the response in its own, transport-specific manner.

This commit establishes a separate table for tracking version 1
commands from version 2 commands. The HTTP server pieces have been
updated to use this new table.

Most commands are marked as both version 1 and version 2, so there is
little practical impact to this change.

A side-effect of this change is we now rely on transport registration
in wireprototypes.TRANSPORTS and certain properties of the protocol
interface. So a test had to be updated to conform.

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.Mar 30 2018, 5:16 PM
durin42 accepted this revision.Apr 3 2018, 11:47 AM
This revision is now accepted and ready to land.Apr 3 2018, 11:47 AM
Closed by commit rHG45b39c69fae0: wireproto: separate commands tables for version 1 and 2 commands (authored by indygreg). · Explain WhyApr 3 2018, 12:51 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

Diff 7557

hgext/largefiles/uisetup.py

proto.getlfile) proto.getlfile)
wireproto.wireprotocommand('statlfile', 'sha', permission='pull')( wireproto.wireprotocommand('statlfile', 'sha', permission='pull')(
proto.statlfile) proto.statlfile)
wireproto.wireprotocommand('lheads', '', permission='pull')( wireproto.wireprotocommand('lheads', '', permission='pull')(
wireproto.heads) wireproto.heads)
# ... and wrap some existing ones # ... and wrap some existing ones
wireproto.commands['heads'].func = proto.heads wireproto.commands['heads'].func = proto.heads
# TODO also wrap wireproto.commandsv2 once heads is implemented there.
extensions.wrapfunction(webcommands, 'decodepath', overrides.decodepath) extensions.wrapfunction(webcommands, 'decodepath', overrides.decodepath)
extensions.wrapfunction(wireproto, '_capabilities', proto._capabilities) extensions.wrapfunction(wireproto, '_capabilities', proto._capabilities)
# can't do this in reposetup because it needs to have happened before # can't do this in reposetup because it needs to have happened before
# wirerepo.__init__ is called # wirerepo.__init__ is called
proto.ssholdcallstream = sshpeer.sshv1peer._callstream proto.ssholdcallstream = sshpeer.sshv1peer._callstream

mercurial/wireproto.py

The intent of this function is to serve as a monkeypatch point for The intent of this function is to serve as a monkeypatch point for
extensions that need commands to operate on different repo views under extensions that need commands to operate on different repo views under
specialized circumstances. specialized circumstances.
""" """
return repo.filtered('served') return repo.filtered('served')
def dispatch(repo, proto, command): def dispatch(repo, proto, command):
repo = getdispatchrepo(repo, proto, command) repo = getdispatchrepo(repo, proto, command)
func, spec = commands[command]
transportversion = wireprototypes.TRANSPORTS[proto.name]['version']
commandtable = commandsv2 if transportversion == 2 else commands
func, spec = commandtable[command]
args = proto.getargs(spec) args = proto.getargs(spec)
return func(repo, proto, *args) return func(repo, proto, *args)
def options(cmd, keys, others): def options(cmd, keys, others):
opts = {} opts = {}
for k in keys: for k in keys:
if k in others: if k in others:
opts[k] = others[k] opts[k] = others[k]
return True return True
# Constants specifying which transports a wire protocol command should be # Constants specifying which transports a wire protocol command should be
# available on. For use with @wireprotocommand. # available on. For use with @wireprotocommand.
POLICY_ALL = 'all' POLICY_ALL = 'all'
POLICY_V1_ONLY = 'v1-only' POLICY_V1_ONLY = 'v1-only'
POLICY_V2_ONLY = 'v2-only' POLICY_V2_ONLY = 'v2-only'
# For version 1 transports.
commands = commanddict() commands = commanddict()
# For version 2 transports.
commandsv2 = commanddict()
def wireprotocommand(name, args='', transportpolicy=POLICY_ALL, def wireprotocommand(name, args='', transportpolicy=POLICY_ALL,
permission='push'): permission='push'):
"""Decorator to declare a wire protocol command. """Decorator to declare a wire protocol command.
``name`` is the name of the wire protocol command being provided. ``name`` is the name of the wire protocol command being provided.
``args`` is a space-delimited list of named arguments that the command ``args`` is a space-delimited list of named arguments that the command
accepts. ``*`` is a special value that says to accept all arguments. accepts. ``*`` is a special value that says to accept all arguments.
``transportpolicy`` is a POLICY_* constant denoting which transports ``transportpolicy`` is a POLICY_* constant denoting which transports
this wire protocol command should be exposed to. By default, commands this wire protocol command should be exposed to. By default, commands
are exposed to all wire protocol transports. are exposed to all wire protocol transports.
``permission`` defines the permission type needed to run this command. ``permission`` defines the permission type needed to run this command.
Can be ``push`` or ``pull``. These roughly map to read-write and read-only, Can be ``push`` or ``pull``. These roughly map to read-write and read-only,
respectively. Default is to assume command requires ``push`` permissions respectively. Default is to assume command requires ``push`` permissions
because otherwise commands not declaring their permissions could modify because otherwise commands not declaring their permissions could modify
a repository that is supposed to be read-only. a repository that is supposed to be read-only.
""" """
if transportpolicy == POLICY_ALL: if transportpolicy == POLICY_ALL:
transports = set(wireprototypes.TRANSPORTS) transports = set(wireprototypes.TRANSPORTS)
transportversions = {1, 2}
elif transportpolicy == POLICY_V1_ONLY: elif transportpolicy == POLICY_V1_ONLY:
transports = {k for k, v in wireprototypes.TRANSPORTS.items() transports = {k for k, v in wireprototypes.TRANSPORTS.items()
if v['version'] == 1} if v['version'] == 1}
transportversions = {1}
elif transportpolicy == POLICY_V2_ONLY: elif transportpolicy == POLICY_V2_ONLY:
transports = {k for k, v in wireprototypes.TRANSPORTS.items() transports = {k for k, v in wireprototypes.TRANSPORTS.items()
if v['version'] == 2} if v['version'] == 2}
transportversions = {2}
else: else:
raise error.ProgrammingError('invalid transport policy value: %s' % raise error.ProgrammingError('invalid transport policy value: %s' %
transportpolicy) transportpolicy)
# Because SSHv2 is a mirror of SSHv1, we allow "batch" commands through to # Because SSHv2 is a mirror of SSHv1, we allow "batch" commands through to
# SSHv2. # SSHv2.
# TODO undo this hack when SSH is using the unified frame protocol. # TODO undo this hack when SSH is using the unified frame protocol.
if name == b'batch': if name == b'batch':
transports.add(wireprototypes.SSHV2) transports.add(wireprototypes.SSHV2)
if permission not in ('push', 'pull'): if permission not in ('push', 'pull'):
raise error.ProgrammingError('invalid wire protocol permission; ' raise error.ProgrammingError('invalid wire protocol permission; '
'got %s; expected "push" or "pull"' % 'got %s; expected "push" or "pull"' %
permission) permission)
def register(func): def register(func):
commands[name] = commandentry(func, args=args, transports=transports, if 1 in transportversions:
if name in commands:
raise error.ProgrammingError('%s command already registered '
'for version 1' % name)
commands[name] = commandentry(func, args=args,
transports=transports,
permission=permission) permission=permission)
if 2 in transportversions:
if name in commandsv2:
raise error.ProgrammingError('%s command already registered '
'for version 2' % name)
commandsv2[name] = commandentry(func, args=args,
transports=transports,
permission=permission)
return func return func
return register return register
# TODO define a more appropriate permissions type to use for this. # TODO define a more appropriate permissions type to use for this.
@wireprotocommand('batch', 'cmds *', permission='pull', @wireprotocommand('batch', 'cmds *', permission='pull',
transportpolicy=POLICY_V1_ONLY) transportpolicy=POLICY_V1_ONLY)
def batch(repo, proto, cmds, others): def batch(repo, proto, cmds, others):
repo = repo.filtered("served") repo = repo.filtered("served")

mercurial/wireprotoserver.py

_processhttpv2reflectrequest(rctx.repo.ui, rctx.repo, req, res) _processhttpv2reflectrequest(rctx.repo.ui, rctx.repo, req, res)
return return
# Extra commands that we handle that aren't really wire protocol # Extra commands that we handle that aren't really wire protocol
# commands. Think extra hard before making this hackery available to # commands. Think extra hard before making this hackery available to
# extension. # extension.
extracommands = {'multirequest'} extracommands = {'multirequest'}
if command not in wireproto.commands and command not in extracommands: if command not in wireproto.commandsv2 and command not in extracommands:
res.status = b'404 Not Found' res.status = b'404 Not Found'
res.headers[b'Content-Type'] = b'text/plain' res.headers[b'Content-Type'] = b'text/plain'
res.setbodybytes(_('unknown wire protocol command: %s\n') % command) res.setbodybytes(_('unknown wire protocol command: %s\n') % command)
return return
repo = rctx.repo repo = rctx.repo
ui = repo.ui ui = repo.ui
proto = httpv2protocolhandler(req, ui) proto = httpv2protocolhandler(req, ui)
if (not wireproto.commands.commandavailable(command, proto) if (not wireproto.commandsv2.commandavailable(command, proto)
and command not in extracommands): and command not in extracommands):
res.status = b'404 Not Found' res.status = b'404 Not Found'
res.headers[b'Content-Type'] = b'text/plain' res.headers[b'Content-Type'] = b'text/plain'
res.setbodybytes(_('invalid wire protocol command: %s') % command) res.setbodybytes(_('invalid wire protocol command: %s') % command)
return return
# TODO consider cases where proxies may add additional Accept headers. # TODO consider cases where proxies may add additional Accept headers.
if req.headers.get(b'Accept') != FRAMINGTYPE: if req.headers.get(b'Accept') != FRAMINGTYPE:
# execute multiple commands. We double check permissions of each command # execute multiple commands. We double check permissions of each command
# as it is invoked to ensure there is no privilege escalation. # as it is invoked to ensure there is no privilege escalation.
# TODO consider allowing multiple commands to regular command URLs # TODO consider allowing multiple commands to regular command URLs
# iff each command is the same. # iff each command is the same.
proto = httpv2protocolhandler(req, ui, args=command['args']) proto = httpv2protocolhandler(req, ui, args=command['args'])
if reqcommand == b'multirequest': if reqcommand == b'multirequest':
if not wireproto.commands.commandavailable(command['command'], proto): if not wireproto.commandsv2.commandavailable(command['command'], proto):
# TODO proper error mechanism # TODO proper error mechanism
res.status = b'200 OK' res.status = b'200 OK'
res.headers[b'Content-Type'] = b'text/plain' res.headers[b'Content-Type'] = b'text/plain'
res.setbodybytes(_('wire protocol command not available: %s') % res.setbodybytes(_('wire protocol command not available: %s') %
command['command']) command['command'])
return True return True
# TODO don't use assert here, since it may be elided by -O. # TODO don't use assert here, since it may be elided by -O.
assert authedperm in (b'ro', b'rw') assert authedperm in (b'ro', b'rw')
wirecommand = wireproto.commands[command['command']] wirecommand = wireproto.commandsv2[command['command']]
assert wirecommand.permission in ('push', 'pull') assert wirecommand.permission in ('push', 'pull')
if authedperm == b'ro' and wirecommand.permission != 'pull': if authedperm == b'ro' and wirecommand.permission != 'pull':
# TODO proper error mechanism # TODO proper error mechanism
res.status = b'403 Forbidden' res.status = b'403 Forbidden'
res.headers[b'Content-Type'] = b'text/plain' res.headers[b'Content-Type'] = b'text/plain'
res.setbodybytes(_('insufficient permissions to execute ' res.setbodybytes(_('insufficient permissions to execute '
'command: %s') % command['command']) 'command: %s') % command['command'])

tests/test-wireproto.py

from __future__ import absolute_import, print_function from __future__ import absolute_import, print_function
from mercurial import ( from mercurial import (
error, error,
pycompat, pycompat,
ui as uimod, ui as uimod,
util, util,
wireproto, wireproto,
wireprototypes, wireprototypes,
) )
stringio = util.stringio stringio = util.stringio
class proto(object): class proto(object):
def __init__(self, args): def __init__(self, args):
self.args = args self.args = args
self.name = 'dummyproto'
def getargs(self, spec): def getargs(self, spec):
args = self.args args = self.args
args.setdefault(b'*', {}) args.setdefault(b'*', {})
names = spec.split() names = spec.split()
return [args[n] for n in names] return [args[n] for n in names]
def checkperm(self, perm): def checkperm(self, perm):
pass pass
wireprototypes.TRANSPORTS['dummyproto'] = {
'transport': 'dummy',
'version': 1,
}
class clientpeer(wireproto.wirepeer): class clientpeer(wireproto.wirepeer):
def __init__(self, serverrepo, ui): def __init__(self, serverrepo, ui):
self.serverrepo = serverrepo self.serverrepo = serverrepo
self._ui = ui self._ui = ui
@property @property
def ui(self): def ui(self):
return self._ui return self._ui