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sshpeer: initial definition and implementation of new SSH protocol...
sshpeer: initial definition and implementation of new SSH protocol The existing SSH protocol has several design flaws. Future commits will elaborate on these flaws as new features are introduced to combat these flaws. For now, hopefully you can take me for my word that a ground up rewrite of the SSH protocol is needed. This commit lays the foundation for a new SSH protocol by defining a mechanism to upgrade the SSH transport channel away from the default (version 1) protocol to something modern (which we'll call "version 2" for now). This upgrade process is detailed in the internals documentation for the wire protocol. The gist of it is the client sends a request line preceding the "hello" command/line which basically says "I'm requesting an upgrade: here's what I support." If the server recognizes that line, it processes the upgrade request and the transport channel is switched to use the new version of the protocol. If not, it sends an empty response, which is how all Mercurial SSH servers from the beginning of time reacted to unknown commands. The upgrade request is effectively ignored and the client continues to use the existing version of the protocol as if nothing happened. The new version of the SSH protocol is completely identical to version 1 aside from the upgrade dance and the bytes that follow. The immediate bytes that follow the protocol switch are defined to be a length framed "capabilities: " line containing the remote's advertised capabilities. In reality, this looks very similar to what the "hello" response would look like. But it will evolve quickly. The methodology by which the protocol will evolve is important. I'm not going to introduce the new protocol all at once. That would likely lead to endless bike shedding and forward progress would stall. Instead, I intend to tricle out new features and diversions from the existing protocol in small, incremental changes. To support the gradual evolution of the protocol, the on-the-wire advertised protocol name contains an "exp" to denote "experimental" and a 4 digit field to capture the sub-version of the protocol. Whenever we make a BC change to the wire protocol, we can increment this version and lock out all older clients because it will appear as a completely different protocol version. This means we can incur as many breaking changes as we want. We don't have to commit to supporting any one feature or idea for a long period of time. We can even evolve the handshake mechanism, because that is defined as being an implementation detail of the negotiated protocol version! Hopefully this lowers the barrier to accepting changes to the protocol and for experimenting with "radical" ideas during its development. In core, sshpeer received most of the attention. We haven't even implemented the server bits for the new protocol in core yet. Instead, we add very primitive support to our test server, mainly just to exercise the added code paths in sshpeer. Differential Revision: https://phab.mercurial-scm.org/D2061 # no-check-commit because of required foo_bar naming

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config.py
280 lines | 9.9 KiB | text/x-python | PythonLexer
# config.py - configuration parsing for Mercurial
#
# Copyright 2009 Matt Mackall <mpm@selenic.com> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import errno
import os
from .i18n import _
from . import (
error,
pycompat,
util,
)
class config(object):
def __init__(self, data=None, includepaths=None):
self._data = {}
self._unset = []
self._includepaths = includepaths or []
if data:
for k in data._data:
self._data[k] = data[k].copy()
self._source = data._source.copy()
else:
self._source = util.cowdict()
def copy(self):
return config(self)
def __contains__(self, section):
return section in self._data
def hasitem(self, section, item):
return item in self._data.get(section, {})
def __getitem__(self, section):
return self._data.get(section, {})
def __iter__(self):
for d in self.sections():
yield d
def update(self, src):
self._source = self._source.preparewrite()
for s, n in src._unset:
ds = self._data.get(s, None)
if ds is not None and n in ds:
self._data[s] = ds.preparewrite()
del self._data[s][n]
del self._source[(s, n)]
for s in src:
ds = self._data.get(s, None)
if ds:
self._data[s] = ds.preparewrite()
else:
self._data[s] = util.cowsortdict()
self._data[s].update(src._data[s])
self._source.update(src._source)
def get(self, section, item, default=None):
return self._data.get(section, {}).get(item, default)
def backup(self, section, item):
"""return a tuple allowing restore to reinstall a previous value
The main reason we need it is because it handles the "no data" case.
"""
try:
value = self._data[section][item]
source = self.source(section, item)
return (section, item, value, source)
except KeyError:
return (section, item)
def source(self, section, item):
return self._source.get((section, item), "")
def sections(self):
return sorted(self._data.keys())
def items(self, section):
return list(self._data.get(section, {}).iteritems())
def set(self, section, item, value, source=""):
if pycompat.ispy3:
assert not isinstance(value, str), (
'config values may not be unicode strings on Python 3')
if section not in self:
self._data[section] = util.cowsortdict()
else:
self._data[section] = self._data[section].preparewrite()
self._data[section][item] = value
if source:
self._source = self._source.preparewrite()
self._source[(section, item)] = source
def restore(self, data):
"""restore data returned by self.backup"""
self._source = self._source.preparewrite()
if len(data) == 4:
# restore old data
section, item, value, source = data
self._data[section] = self._data[section].preparewrite()
self._data[section][item] = value
self._source[(section, item)] = source
else:
# no data before, remove everything
section, item = data
if section in self._data:
self._data[section].pop(item, None)
self._source.pop((section, item), None)
def parse(self, src, data, sections=None, remap=None, include=None):
sectionre = util.re.compile(br'\[([^\[]+)\]')
itemre = util.re.compile(br'([^=\s][^=]*?)\s*=\s*(.*\S|)')
contre = util.re.compile(br'\s+(\S|\S.*\S)\s*$')
emptyre = util.re.compile(br'(;|#|\s*$)')
commentre = util.re.compile(br'(;|#)')
unsetre = util.re.compile(br'%unset\s+(\S+)')
includere = util.re.compile(br'%include\s+(\S|\S.*\S)\s*$')
section = ""
item = None
line = 0
cont = False
if remap:
section = remap.get(section, section)
for l in data.splitlines(True):
line += 1
if line == 1 and l.startswith('\xef\xbb\xbf'):
# Someone set us up the BOM
l = l[3:]
if cont:
if commentre.match(l):
continue
m = contre.match(l)
if m:
if sections and section not in sections:
continue
v = self.get(section, item) + "\n" + m.group(1)
self.set(section, item, v, "%s:%d" % (src, line))
continue
item = None
cont = False
m = includere.match(l)
if m and include:
expanded = util.expandpath(m.group(1))
includepaths = [os.path.dirname(src)] + self._includepaths
for base in includepaths:
inc = os.path.normpath(os.path.join(base, expanded))
try:
include(inc, remap=remap, sections=sections)
break
except IOError as inst:
if inst.errno != errno.ENOENT:
raise error.ParseError(_("cannot include %s (%s)")
% (inc, inst.strerror),
"%s:%s" % (src, line))
continue
if emptyre.match(l):
continue
m = sectionre.match(l)
if m:
section = m.group(1)
if remap:
section = remap.get(section, section)
if section not in self:
self._data[section] = util.cowsortdict()
continue
m = itemre.match(l)
if m:
item = m.group(1)
cont = True
if sections and section not in sections:
continue
self.set(section, item, m.group(2), "%s:%d" % (src, line))
continue
m = unsetre.match(l)
if m:
name = m.group(1)
if sections and section not in sections:
continue
if self.get(section, name) is not None:
self._data[section] = self._data[section].preparewrite()
del self._data[section][name]
self._unset.append((section, name))
continue
raise error.ParseError(l.rstrip(), ("%s:%s" % (src, line)))
def read(self, path, fp=None, sections=None, remap=None):
if not fp:
fp = util.posixfile(path, 'rb')
assert getattr(fp, 'mode', r'rb') == r'rb', (
'config files must be opened in binary mode, got fp=%r mode=%r' % (
fp, fp.mode))
self.parse(path, fp.read(),
sections=sections, remap=remap, include=self.read)
def parselist(value):
"""parse a configuration value as a list of comma/space separated strings
>>> parselist(b'this,is "a small" ,test')
['this', 'is', 'a small', 'test']
"""
def _parse_plain(parts, s, offset):
whitespace = False
while offset < len(s) and (s[offset:offset + 1].isspace()
or s[offset:offset + 1] == ','):
whitespace = True
offset += 1
if offset >= len(s):
return None, parts, offset
if whitespace:
parts.append('')
if s[offset:offset + 1] == '"' and not parts[-1]:
return _parse_quote, parts, offset + 1
elif s[offset:offset + 1] == '"' and parts[-1][-1] == '\\':
parts[-1] = parts[-1][:-1] + s[offset:offset + 1]
return _parse_plain, parts, offset + 1
parts[-1] += s[offset:offset + 1]
return _parse_plain, parts, offset + 1
def _parse_quote(parts, s, offset):
if offset < len(s) and s[offset:offset + 1] == '"': # ""
parts.append('')
offset += 1
while offset < len(s) and (s[offset:offset + 1].isspace() or
s[offset:offset + 1] == ','):
offset += 1
return _parse_plain, parts, offset
while offset < len(s) and s[offset:offset + 1] != '"':
if (s[offset:offset + 1] == '\\' and offset + 1 < len(s)
and s[offset + 1:offset + 2] == '"'):
offset += 1
parts[-1] += '"'
else:
parts[-1] += s[offset:offset + 1]
offset += 1
if offset >= len(s):
real_parts = _configlist(parts[-1])
if not real_parts:
parts[-1] = '"'
else:
real_parts[0] = '"' + real_parts[0]
parts = parts[:-1]
parts.extend(real_parts)
return None, parts, offset
offset += 1
while offset < len(s) and s[offset:offset + 1] in [' ', ',']:
offset += 1
if offset < len(s):
if offset + 1 == len(s) and s[offset:offset + 1] == '"':
parts[-1] += '"'
offset += 1
else:
parts.append('')
else:
return None, parts, offset
return _parse_plain, parts, offset
def _configlist(s):
s = s.rstrip(' ,')
if not s:
return []
parser, parts, offset = _parse_plain, [''], 0
while parser:
parser, parts, offset = parser(parts, s, offset)
return parts
if value is not None and isinstance(value, bytes):
result = _configlist(value.lstrip(' ,\n'))
else:
result = value
return result or []