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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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server.py
347 lines | 11.9 KiB | text/x-python | PythonLexer
# hgweb/server.py - The standalone hg web server.
#
# Copyright 21 May 2005 - (c) 2005 Jake Edge <jake@edge2.net>
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# 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
import socket
import sys
import traceback
from ..i18n import _
from .. import (
encoding,
error,
pycompat,
util,
)
httpservermod = util.httpserver
socketserver = util.socketserver
urlerr = util.urlerr
urlreq = util.urlreq
from . import (
common,
)
def _splitURI(uri):
"""Return path and query that has been split from uri
Just like CGI environment, the path is unquoted, the query is
not.
"""
if r'?' in uri:
path, query = uri.split(r'?', 1)
else:
path, query = uri, r''
return urlreq.unquote(path), query
class _error_logger(object):
def __init__(self, handler):
self.handler = handler
def flush(self):
pass
def write(self, str):
self.writelines(str.split('\n'))
def writelines(self, seq):
for msg in seq:
self.handler.log_error("HG error: %s", msg)
class _httprequesthandler(httpservermod.basehttprequesthandler):
url_scheme = 'http'
@staticmethod
def preparehttpserver(httpserver, ui):
"""Prepare .socket of new HTTPServer instance"""
def __init__(self, *args, **kargs):
self.protocol_version = r'HTTP/1.1'
httpservermod.basehttprequesthandler.__init__(self, *args, **kargs)
def _log_any(self, fp, format, *args):
fp.write(pycompat.sysbytes(
r"%s - - [%s] %s" % (self.client_address[0],
self.log_date_time_string(),
format % args)) + '\n')
fp.flush()
def log_error(self, format, *args):
self._log_any(self.server.errorlog, format, *args)
def log_message(self, format, *args):
self._log_any(self.server.accesslog, format, *args)
def log_request(self, code=r'-', size=r'-'):
xheaders = []
if util.safehasattr(self, 'headers'):
xheaders = [h for h in self.headers.items()
if h[0].startswith(r'x-')]
self.log_message(r'"%s" %s %s%s',
self.requestline, str(code), str(size),
r''.join([r' %s:%s' % h for h in sorted(xheaders)]))
def do_write(self):
try:
self.do_hgweb()
except socket.error as inst:
if inst[0] != errno.EPIPE:
raise
def do_POST(self):
try:
self.do_write()
except Exception:
self._start_response("500 Internal Server Error", [])
self._write("Internal Server Error")
self._done()
tb = r"".join(traceback.format_exception(*sys.exc_info()))
# We need a native-string newline to poke in the log
# message, because we won't get a newline when using an
# r-string. This is the easy way out.
newline = chr(10)
self.log_error(r"Exception happened during processing "
r"request '%s':%s%s", self.path, newline, tb)
def do_GET(self):
self.do_POST()
def do_hgweb(self):
self.sent_headers = False
path, query = _splitURI(self.path)
env = {}
env[r'GATEWAY_INTERFACE'] = r'CGI/1.1'
env[r'REQUEST_METHOD'] = self.command
env[r'SERVER_NAME'] = self.server.server_name
env[r'SERVER_PORT'] = str(self.server.server_port)
env[r'REQUEST_URI'] = self.path
env[r'SCRIPT_NAME'] = self.server.prefix
env[r'PATH_INFO'] = path[len(self.server.prefix):]
env[r'REMOTE_HOST'] = self.client_address[0]
env[r'REMOTE_ADDR'] = self.client_address[0]
if query:
env[r'QUERY_STRING'] = query
if pycompat.ispy3:
if self.headers.get_content_type() is None:
env[r'CONTENT_TYPE'] = self.headers.get_default_type()
else:
env[r'CONTENT_TYPE'] = self.headers.get_content_type()
length = self.headers.get('content-length')
else:
if self.headers.typeheader is None:
env[r'CONTENT_TYPE'] = self.headers.type
else:
env[r'CONTENT_TYPE'] = self.headers.typeheader
length = self.headers.getheader('content-length')
if length:
env[r'CONTENT_LENGTH'] = length
for header in [h for h in self.headers.keys()
if h not in ('content-type', 'content-length')]:
hkey = r'HTTP_' + header.replace(r'-', r'_').upper()
hval = self.headers.get(header)
hval = hval.replace(r'\n', r'').strip()
if hval:
env[hkey] = hval
env[r'SERVER_PROTOCOL'] = self.request_version
env[r'wsgi.version'] = (1, 0)
env[r'wsgi.url_scheme'] = self.url_scheme
if env.get(r'HTTP_EXPECT', '').lower() == '100-continue':
self.rfile = common.continuereader(self.rfile, self.wfile.write)
env[r'wsgi.input'] = self.rfile
env[r'wsgi.errors'] = _error_logger(self)
env[r'wsgi.multithread'] = isinstance(self.server,
socketserver.ThreadingMixIn)
env[r'wsgi.multiprocess'] = isinstance(self.server,
socketserver.ForkingMixIn)
env[r'wsgi.run_once'] = 0
self.saved_status = None
self.saved_headers = []
self.length = None
self._chunked = None
for chunk in self.server.application(env, self._start_response):
self._write(chunk)
if not self.sent_headers:
self.send_headers()
self._done()
def send_headers(self):
if not self.saved_status:
raise AssertionError("Sending headers before "
"start_response() called")
saved_status = self.saved_status.split(None, 1)
saved_status[0] = int(saved_status[0])
self.send_response(*saved_status)
self.length = None
self._chunked = False
for h in self.saved_headers:
self.send_header(*h)
if h[0].lower() == 'content-length':
self.length = int(h[1])
if (self.length is None and
saved_status[0] != common.HTTP_NOT_MODIFIED):
self._chunked = (not self.close_connection and
self.request_version == "HTTP/1.1")
if self._chunked:
self.send_header(r'Transfer-Encoding', r'chunked')
else:
self.send_header(r'Connection', r'close')
self.end_headers()
self.sent_headers = True
def _start_response(self, http_status, headers, exc_info=None):
code, msg = http_status.split(None, 1)
code = int(code)
self.saved_status = http_status
bad_headers = ('connection', 'transfer-encoding')
self.saved_headers = [h for h in headers
if h[0].lower() not in bad_headers]
return self._write
def _write(self, data):
if not self.saved_status:
raise AssertionError("data written before start_response() called")
elif not self.sent_headers:
self.send_headers()
if self.length is not None:
if len(data) > self.length:
raise AssertionError("Content-length header sent, but more "
"bytes than specified are being written.")
self.length = self.length - len(data)
elif self._chunked and data:
data = '%x\r\n%s\r\n' % (len(data), data)
self.wfile.write(data)
self.wfile.flush()
def _done(self):
if self._chunked:
self.wfile.write('0\r\n\r\n')
self.wfile.flush()
class _httprequesthandlerssl(_httprequesthandler):
"""HTTPS handler based on Python's ssl module"""
url_scheme = 'https'
@staticmethod
def preparehttpserver(httpserver, ui):
try:
from .. import sslutil
sslutil.modernssl
except ImportError:
raise error.Abort(_("SSL support is unavailable"))
certfile = ui.config('web', 'certificate')
# These config options are currently only meant for testing. Use
# at your own risk.
cafile = ui.config('devel', 'servercafile')
reqcert = ui.configbool('devel', 'serverrequirecert')
httpserver.socket = sslutil.wrapserversocket(httpserver.socket,
ui,
certfile=certfile,
cafile=cafile,
requireclientcert=reqcert)
def setup(self):
self.connection = self.request
self.rfile = socket._fileobject(self.request, "rb", self.rbufsize)
self.wfile = socket._fileobject(self.request, "wb", self.wbufsize)
try:
import threading
threading.activeCount() # silence pyflakes and bypass demandimport
_mixin = socketserver.ThreadingMixIn
except ImportError:
if util.safehasattr(os, "fork"):
_mixin = socketserver.ForkingMixIn
else:
class _mixin(object):
pass
def openlog(opt, default):
if opt and opt != '-':
return open(opt, 'a')
return default
class MercurialHTTPServer(_mixin, httpservermod.httpserver, object):
# SO_REUSEADDR has broken semantics on windows
if pycompat.iswindows:
allow_reuse_address = 0
def __init__(self, ui, app, addr, handler, **kwargs):
httpservermod.httpserver.__init__(self, addr, handler, **kwargs)
self.daemon_threads = True
self.application = app
handler.preparehttpserver(self, ui)
prefix = ui.config('web', 'prefix')
if prefix:
prefix = '/' + prefix.strip('/')
self.prefix = prefix
alog = openlog(ui.config('web', 'accesslog'), ui.fout)
elog = openlog(ui.config('web', 'errorlog'), ui.ferr)
self.accesslog = alog
self.errorlog = elog
self.addr, self.port = self.socket.getsockname()[0:2]
self.fqaddr = socket.getfqdn(addr[0])
class IPv6HTTPServer(MercurialHTTPServer):
address_family = getattr(socket, 'AF_INET6', None)
def __init__(self, *args, **kwargs):
if self.address_family is None:
raise error.RepoError(_('IPv6 is not available on this system'))
super(IPv6HTTPServer, self).__init__(*args, **kwargs)
def create_server(ui, app):
if ui.config('web', 'certificate'):
handler = _httprequesthandlerssl
else:
handler = _httprequesthandler
if ui.configbool('web', 'ipv6'):
cls = IPv6HTTPServer
else:
cls = MercurialHTTPServer
# ugly hack due to python issue5853 (for threaded use)
try:
import mimetypes
mimetypes.init()
except UnicodeDecodeError:
# Python 2.x's mimetypes module attempts to decode strings
# from Windows' ANSI APIs as ascii (fail), then re-encode them
# as ascii (clown fail), because the default Python Unicode
# codec is hardcoded as ascii.
sys.argv # unwrap demand-loader so that reload() works
reload(sys) # resurrect sys.setdefaultencoding()
oldenc = sys.getdefaultencoding()
sys.setdefaultencoding("latin1") # or any full 8-bit encoding
mimetypes.init()
sys.setdefaultencoding(oldenc)
address = ui.config('web', 'address')
port = util.getport(ui.config('web', 'port'))
try:
return cls(ui, app, (address, port), handler)
except socket.error as inst:
raise error.Abort(_("cannot start server at '%s:%d': %s")
% (address, port, encoding.strtolocal(inst.args[1])))