hgweb: refactor the request draining code
The previous code for draining was only invoked in a few places in
the wire protocol. Behavior wasn't consist. Furthermore, it was
difficult to reason about.
With us converting the input stream to a capped reader, it is now
safe to always drain the input stream when its size is known because
we can never overrun the input and read into the next HTTP request.
The only question is "should we?"
This commit changes the draining code so every request is examined.
Draining now kicks in for a few requests where it wouldn't before.
But I think the code is sufficiently restricted so the behavior is
safe. Possibly the most dangerous part of this code is the issuing
of Connection: close for POST and PUT requests that don't have a
Content-Length. I don't think there are any such uses in our WSGI
application, so this should be safe.
In the near future, I plan to significantly refactor the WSGI
response handling. I anticipate this code evolving a bit. So any
minor regressions around draining or connection closing behavior
might be fixed as a result of that work.
All tests pass with this change. That scares me a bit because it
means we are lacking low-level tests for the HTTP protocol.
Differential Revision: https://phab.mercurial-scm.org/D2769
# 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
import wsgiref.validate
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'] = pycompat.sysstr(self.server.prefix)
env[r'PATH_INFO'] = pycompat.sysstr(path[len(self.server.prefix):])
env[r'REMOTE_HOST'] = self.client_address[0]
env[r'REMOTE_ADDR'] = self.client_address[0]
env[r'QUERY_STRING'] = query or r''
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'] = pycompat.sysstr(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
wsgiref.validate.check_environ(env)
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 = self.request.makefile(r"rb", self.rbufsize)
self.wfile = self.request.makefile(r"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, 'ab')
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])))