view mercurial/url.py @ 36456:23d12524a202

http: drop custom http client logic

Eight and a half years ago, as my starter bug on code.google.com, I
investigated a mysterious "broken pipe" error from seemingly random
clients[0]. That investigation revealed a tragic story: the Python
standard library's httplib was (and remains) barely functional. During
large POSTs, if a server responds early with an error (even a
permission denied error!) the client only notices that the server
closed the connection and everything breaks. Such server behavior is
implicitly legal under RFC 2616 (the latest HTTP RFC as of when I was
last working on this), and my understanding is that later RFCs have
made it explicitly legal to respond early with any status code outside
the 2xx range.

I embarked, probably foolishly, on a journey to write a new http
library with better overall behavior. The http library appears to work
well in most cases, but it can get confused in the presence of
proxies, and it depends on select(2) which limits its utility if a lot
of file descriptors are open. I haven't touched the http library in
almost two years, and in the interim the Python community has
discovered a better way[1] of writing network code. In theory some day
urllib3 will have its own home-grown http library built on h11[2], or
we could do that. Either way, it's time to declare our current
confusingly-named "http2" client logic and move on. I do hope to
revisit this some day: it's still garbage that we can't even respond
with a 401 or 403 without reading the entire POST body from the
client, but the goalposts on writing a new http client library have
moved substantially. We're almost certainly better off just switching
to requests and eventually picking up their http fixes than trying to
live with something that realistically only we'll ever use. Another
approach would be to write an adapter so that Mercurial can use pycurl
if it's installed. Neither of those approaches seem like they should
be investigated prior to a release of Mercurial that works on Python
3: that's where the mindshare is going to be for any improvements to
the state of the http client art.

0: http://web.archive.org/web/20130501031801/http://code.google.com/p/support/issues/detail?id=2716
1: http://sans-io.readthedocs.io/
2: https://github.com/njsmith/h11

Differential Revision: https://phab.mercurial-scm.org/D2444

# url.py - HTTP handling for mercurial
#
# Copyright 2005, 2006, 2007, 2008 Matt Mackall <[e-mail]>
# Copyright 2006, 2007 Alexis S. L. Carvalho <[e-mail]>
# Copyright 2006 Vadim Gelfer <[e-mail]>
#
# 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 base64
import os
import socket

from .i18n import _
from . import (
    encoding,
    error,
    httpconnection as httpconnectionmod,
    keepalive,
    pycompat,
    sslutil,
    urllibcompat,
    util,
)

httplib = util.httplib
stringio = util.stringio
urlerr = util.urlerr
urlreq = util.urlreq

def escape(s, quote=None):
    '''Replace special characters "&", "<" and ">" to HTML-safe sequences.
    If the optional flag quote is true, the quotation mark character (")
    is also translated.

    This is the same as cgi.escape in Python, but always operates on
    bytes, whereas cgi.escape in Python 3 only works on unicodes.
    '''
    s = s.replace(b"&", b"&amp;")
    s = s.replace(b"<", b"&lt;")
    s = s.replace(b">", b"&gt;")
    if quote:
        s = s.replace(b'"', b"&quot;")
    return s

class passwordmgr(object):
    def __init__(self, ui, passwddb):
        self.ui = ui
        self.passwddb = passwddb

    def add_password(self, realm, uri, user, passwd):
        return self.passwddb.add_password(realm, uri, user, passwd)

    def find_user_password(self, realm, authuri):
        authinfo = self.passwddb.find_user_password(realm, authuri)
        user, passwd = authinfo
        if user and passwd:
            self._writedebug(user, passwd)
            return (user, passwd)

        if not user or not passwd:
            res = httpconnectionmod.readauthforuri(self.ui, authuri, user)
            if res:
                group, auth = res
                user, passwd = auth.get('username'), auth.get('password')
                self.ui.debug("using auth.%s.* for authentication\n" % group)
        if not user or not passwd:
            u = util.url(authuri)
            u.query = None
            if not self.ui.interactive():
                raise error.Abort(_('http authorization required for %s') %
                                  util.hidepassword(bytes(u)))

            self.ui.write(_("http authorization required for %s\n") %
                          util.hidepassword(bytes(u)))
            self.ui.write(_("realm: %s\n") % realm)
            if user:
                self.ui.write(_("user: %s\n") % user)
            else:
                user = self.ui.prompt(_("user:"), default=None)

            if not passwd:
                passwd = self.ui.getpass()

        self.passwddb.add_password(realm, authuri, user, passwd)
        self._writedebug(user, passwd)
        return (user, passwd)

    def _writedebug(self, user, passwd):
        msg = _('http auth: user %s, password %s\n')
        self.ui.debug(msg % (user, passwd and '*' * len(passwd) or 'not set'))

    def find_stored_password(self, authuri):
        return self.passwddb.find_user_password(None, authuri)

class proxyhandler(urlreq.proxyhandler):
    def __init__(self, ui):
        proxyurl = (ui.config("http_proxy", "host") or
                        encoding.environ.get('http_proxy'))
        # XXX proxyauthinfo = None

        if proxyurl:
            # proxy can be proper url or host[:port]
            if not (proxyurl.startswith('http:') or
                    proxyurl.startswith('https:')):
                proxyurl = 'http://' + proxyurl + '/'
            proxy = util.url(proxyurl)
            if not proxy.user:
                proxy.user = ui.config("http_proxy", "user")
                proxy.passwd = ui.config("http_proxy", "passwd")

            # see if we should use a proxy for this url
            no_list = ["localhost", "127.0.0.1"]
            no_list.extend([p.lower() for
                            p in ui.configlist("http_proxy", "no")])
            no_list.extend([p.strip().lower() for
                            p in encoding.environ.get("no_proxy", '').split(',')
                            if p.strip()])
            # "http_proxy.always" config is for running tests on localhost
            if ui.configbool("http_proxy", "always"):
                self.no_list = []
            else:
                self.no_list = no_list

            proxyurl = bytes(proxy)
            proxies = {'http': proxyurl, 'https': proxyurl}
            ui.debug('proxying through %s\n' % util.hidepassword(proxyurl))
        else:
            proxies = {}

        urlreq.proxyhandler.__init__(self, proxies)
        self.ui = ui

    def proxy_open(self, req, proxy, type_):
        host = urllibcompat.gethost(req).split(':')[0]
        for e in self.no_list:
            if host == e:
                return None
            if e.startswith('*.') and host.endswith(e[2:]):
                return None
            if e.startswith('.') and host.endswith(e[1:]):
                return None

        return urlreq.proxyhandler.proxy_open(self, req, proxy, type_)

def _gen_sendfile(orgsend):
    def _sendfile(self, data):
        # send a file
        if isinstance(data, httpconnectionmod.httpsendfile):
            # if auth required, some data sent twice, so rewind here
            data.seek(0)
            for chunk in util.filechunkiter(data):
                orgsend(self, chunk)
        else:
            orgsend(self, data)
    return _sendfile

has_https = util.safehasattr(urlreq, 'httpshandler')

class httpconnection(keepalive.HTTPConnection):
    # must be able to send big bundle as stream.
    send = _gen_sendfile(keepalive.HTTPConnection.send)

    def getresponse(self):
        proxyres = getattr(self, 'proxyres', None)
        if proxyres:
            if proxyres.will_close:
                self.close()
            self.proxyres = None
            return proxyres
        return keepalive.HTTPConnection.getresponse(self)

# general transaction handler to support different ways to handle
# HTTPS proxying before and after Python 2.6.3.
def _generic_start_transaction(handler, h, req):
    tunnel_host = getattr(req, '_tunnel_host', None)
    if tunnel_host:
        if tunnel_host[:7] not in ['http://', 'https:/']:
            tunnel_host = 'https://' + tunnel_host
        new_tunnel = True
    else:
        tunnel_host = urllibcompat.getselector(req)
        new_tunnel = False

    if new_tunnel or tunnel_host == urllibcompat.getfullurl(req): # has proxy
        u = util.url(tunnel_host)
        if new_tunnel or u.scheme == 'https': # only use CONNECT for HTTPS
            h.realhostport = ':'.join([u.host, (u.port or '443')])
            h.headers = req.headers.copy()
            h.headers.update(handler.parent.addheaders)
            return

    h.realhostport = None
    h.headers = None

def _generic_proxytunnel(self):
    proxyheaders = dict(
            [(x, self.headers[x]) for x in self.headers
             if x.lower().startswith('proxy-')])
    self.send('CONNECT %s HTTP/1.0\r\n' % self.realhostport)
    for header in proxyheaders.iteritems():
        self.send('%s: %s\r\n' % header)
    self.send('\r\n')

    # majority of the following code is duplicated from
    # httplib.HTTPConnection as there are no adequate places to
    # override functions to provide the needed functionality
    res = self.response_class(self.sock,
                              strict=self.strict,
                              method=self._method)

    while True:
        version, status, reason = res._read_status()
        if status != httplib.CONTINUE:
            break
        # skip lines that are all whitespace
        list(iter(lambda: res.fp.readline().strip(), ''))
    res.status = status
    res.reason = reason.strip()

    if res.status == 200:
        # skip lines until we find a blank line
        list(iter(res.fp.readline, '\r\n'))
        return True

    if version == 'HTTP/1.0':
        res.version = 10
    elif version.startswith('HTTP/1.'):
        res.version = 11
    elif version == 'HTTP/0.9':
        res.version = 9
    else:
        raise httplib.UnknownProtocol(version)

    if res.version == 9:
        res.length = None
        res.chunked = 0
        res.will_close = 1
        res.msg = httplib.HTTPMessage(stringio())
        return False

    res.msg = httplib.HTTPMessage(res.fp)
    res.msg.fp = None

    # are we using the chunked-style of transfer encoding?
    trenc = res.msg.getheader('transfer-encoding')
    if trenc and trenc.lower() == "chunked":
        res.chunked = 1
        res.chunk_left = None
    else:
        res.chunked = 0

    # will the connection close at the end of the response?
    res.will_close = res._check_close()

    # do we have a Content-Length?
    # NOTE: RFC 2616, section 4.4, #3 says we ignore this if
    # transfer-encoding is "chunked"
    length = res.msg.getheader('content-length')
    if length and not res.chunked:
        try:
            res.length = int(length)
        except ValueError:
            res.length = None
        else:
            if res.length < 0:  # ignore nonsensical negative lengths
                res.length = None
    else:
        res.length = None

    # does the body have a fixed length? (of zero)
    if (status == httplib.NO_CONTENT or status == httplib.NOT_MODIFIED or
        100 <= status < 200 or # 1xx codes
        res._method == 'HEAD'):
        res.length = 0

    # if the connection remains open, and we aren't using chunked, and
    # a content-length was not provided, then assume that the connection
    # WILL close.
    if (not res.will_close and
       not res.chunked and
       res.length is None):
        res.will_close = 1

    self.proxyres = res

    return False

class httphandler(keepalive.HTTPHandler):
    def http_open(self, req):
        return self.do_open(httpconnection, req)

    def _start_transaction(self, h, req):
        _generic_start_transaction(self, h, req)
        return keepalive.HTTPHandler._start_transaction(self, h, req)

if has_https:
    class httpsconnection(httplib.HTTPConnection):
        response_class = keepalive.HTTPResponse
        default_port = httplib.HTTPS_PORT
        # must be able to send big bundle as stream.
        send = _gen_sendfile(keepalive.safesend)
        getresponse = keepalive.wrapgetresponse(httplib.HTTPConnection)

        def __init__(self, host, port=None, key_file=None, cert_file=None,
                     *args, **kwargs):
            httplib.HTTPConnection.__init__(self, host, port, *args, **kwargs)
            self.key_file = key_file
            self.cert_file = cert_file

        def connect(self):
            self.sock = socket.create_connection((self.host, self.port))

            host = self.host
            if self.realhostport: # use CONNECT proxy
                _generic_proxytunnel(self)
                host = self.realhostport.rsplit(':', 1)[0]
            self.sock = sslutil.wrapsocket(
                self.sock, self.key_file, self.cert_file, ui=self.ui,
                serverhostname=host)
            sslutil.validatesocket(self.sock)

    class httpshandler(keepalive.KeepAliveHandler, urlreq.httpshandler):
        def __init__(self, ui):
            keepalive.KeepAliveHandler.__init__(self)
            urlreq.httpshandler.__init__(self)
            self.ui = ui
            self.pwmgr = passwordmgr(self.ui,
                                     self.ui.httppasswordmgrdb)

        def _start_transaction(self, h, req):
            _generic_start_transaction(self, h, req)
            return keepalive.KeepAliveHandler._start_transaction(self, h, req)

        def https_open(self, req):
            # urllibcompat.getfullurl() does not contain credentials
            # and we may need them to match the certificates.
            url = urllibcompat.getfullurl(req)
            user, password = self.pwmgr.find_stored_password(url)
            res = httpconnectionmod.readauthforuri(self.ui, url, user)
            if res:
                group, auth = res
                self.auth = auth
                self.ui.debug("using auth.%s.* for authentication\n" % group)
            else:
                self.auth = None
            return self.do_open(self._makeconnection, req)

        def _makeconnection(self, host, port=None, *args, **kwargs):
            keyfile = None
            certfile = None

            if len(args) >= 1: # key_file
                keyfile = args[0]
            if len(args) >= 2: # cert_file
                certfile = args[1]
            args = args[2:]

            # if the user has specified different key/cert files in
            # hgrc, we prefer these
            if self.auth and 'key' in self.auth and 'cert' in self.auth:
                keyfile = self.auth['key']
                certfile = self.auth['cert']

            conn = httpsconnection(host, port, keyfile, certfile, *args,
                                   **kwargs)
            conn.ui = self.ui
            return conn

class httpdigestauthhandler(urlreq.httpdigestauthhandler):
    def __init__(self, *args, **kwargs):
        urlreq.httpdigestauthhandler.__init__(self, *args, **kwargs)
        self.retried_req = None

    def reset_retry_count(self):
        # Python 2.6.5 will call this on 401 or 407 errors and thus loop
        # forever. We disable reset_retry_count completely and reset in
        # http_error_auth_reqed instead.
        pass

    def http_error_auth_reqed(self, auth_header, host, req, headers):
        # Reset the retry counter once for each request.
        if req is not self.retried_req:
            self.retried_req = req
            self.retried = 0
        return urlreq.httpdigestauthhandler.http_error_auth_reqed(
                    self, auth_header, host, req, headers)

class httpbasicauthhandler(urlreq.httpbasicauthhandler):
    def __init__(self, *args, **kwargs):
        self.auth = None
        urlreq.httpbasicauthhandler.__init__(self, *args, **kwargs)
        self.retried_req = None

    def http_request(self, request):
        if self.auth:
            request.add_unredirected_header(self.auth_header, self.auth)

        return request

    def https_request(self, request):
        if self.auth:
            request.add_unredirected_header(self.auth_header, self.auth)

        return request

    def reset_retry_count(self):
        # Python 2.6.5 will call this on 401 or 407 errors and thus loop
        # forever. We disable reset_retry_count completely and reset in
        # http_error_auth_reqed instead.
        pass

    def http_error_auth_reqed(self, auth_header, host, req, headers):
        # Reset the retry counter once for each request.
        if req is not self.retried_req:
            self.retried_req = req
            self.retried = 0
        return urlreq.httpbasicauthhandler.http_error_auth_reqed(
                        self, auth_header, host, req, headers)

    def retry_http_basic_auth(self, host, req, realm):
        user, pw = self.passwd.find_user_password(
            realm, urllibcompat.getfullurl(req))
        if pw is not None:
            raw = "%s:%s" % (user, pw)
            auth = 'Basic %s' % base64.b64encode(raw).strip()
            if req.get_header(self.auth_header, None) == auth:
                return None
            self.auth = auth
            req.add_unredirected_header(self.auth_header, auth)
            return self.parent.open(req)
        else:
            return None

class cookiehandler(urlreq.basehandler):
    def __init__(self, ui):
        self.cookiejar = None

        cookiefile = ui.config('auth', 'cookiefile')
        if not cookiefile:
            return

        cookiefile = util.expandpath(cookiefile)
        try:
            cookiejar = util.cookielib.MozillaCookieJar(cookiefile)
            cookiejar.load()
            self.cookiejar = cookiejar
        except util.cookielib.LoadError as e:
            ui.warn(_('(error loading cookie file %s: %s; continuing without '
                      'cookies)\n') % (cookiefile, util.forcebytestr(e)))

    def http_request(self, request):
        if self.cookiejar:
            self.cookiejar.add_cookie_header(request)

        return request

    def https_request(self, request):
        if self.cookiejar:
            self.cookiejar.add_cookie_header(request)

        return request

handlerfuncs = []

def opener(ui, authinfo=None, useragent=None):
    '''
    construct an opener suitable for urllib2
    authinfo will be added to the password manager
    '''
    handlers = [httphandler()]
    if has_https:
        handlers.append(httpshandler(ui))

    handlers.append(proxyhandler(ui))

    passmgr = passwordmgr(ui, ui.httppasswordmgrdb)
    if authinfo is not None:
        realm, uris, user, passwd = authinfo
        saveduser, savedpass = passmgr.find_stored_password(uris[0])
        if user != saveduser or passwd:
            passmgr.add_password(realm, uris, user, passwd)
        ui.debug('http auth: user %s, password %s\n' %
                 (user, passwd and '*' * len(passwd) or 'not set'))

    handlers.extend((httpbasicauthhandler(passmgr),
                     httpdigestauthhandler(passmgr)))
    handlers.extend([h(ui, passmgr) for h in handlerfuncs])
    handlers.append(cookiehandler(ui))
    opener = urlreq.buildopener(*handlers)

    # The user agent should should *NOT* be used by servers for e.g.
    # protocol detection or feature negotiation: there are other
    # facilities for that.
    #
    # "mercurial/proto-1.0" was the original user agent string and
    # exists for backwards compatibility reasons.
    #
    # The "(Mercurial %s)" string contains the distribution
    # name and version. Other client implementations should choose their
    # own distribution name. Since servers should not be using the user
    # agent string for anything, clients should be able to define whatever
    # user agent they deem appropriate.
    #
    # The custom user agent is for lfs, because unfortunately some servers
    # do look at this value.
    if not useragent:
        agent = 'mercurial/proto-1.0 (Mercurial %s)' % util.version()
        opener.addheaders = [(r'User-agent', pycompat.sysstr(agent))]
    else:
        opener.addheaders = [(r'User-agent', pycompat.sysstr(useragent))]

    # This header should only be needed by wire protocol requests. But it has
    # been sent on all requests since forever. We keep sending it for backwards
    # compatibility reasons. Modern versions of the wire protocol use
    # X-HgProto-<N> for advertising client support.
    opener.addheaders.append((r'Accept', r'application/mercurial-0.1'))
    return opener

def open(ui, url_, data=None):
    u = util.url(url_)
    if u.scheme:
        u.scheme = u.scheme.lower()
        url_, authinfo = u.authinfo()
    else:
        path = util.normpath(os.path.abspath(url_))
        url_ = 'file://' + urlreq.pathname2url(path)
        authinfo = None
    return opener(ui, authinfo).open(url_, data)