mercurial/httppeer.py

httppeer: don't accept very old media types (BC)

Versions of Mercurial older than 1.0 emitted the text/plain
and application/hg-changegroup media types in response to wire
protocol commands.

Way back in 8760d0c83b9b in 2005, the code validating these media
types was added, presumably for backwards compatibility. 0b245edec124
a short time before that commit changed things from text/plain and
application/hg-changegroup to application/mercurial-0.1 and
application/hg-0.1. 8760d0c83b9b seemed to indicate ("for now") that
the BC compatibility was temporary. But that code has lived until
this day.

It has been more than 10 years and nobody should be running pre 1.0
servers.

Pretty much the only risk to this is if there's a server somewhere
advertising the old media types or server software is interfering
and not letting Mercurial send the proper Content-Type header. I
think the chances are rare.

The wire protocol docs were created (by me) from reading existing
code. So the deletions don't constitute a spec change as much as
reflecting the reality of how things have been for years.

.. bc::

   The HTTP client no longer accepts text/plain and
   application/hg-changegroup Content-Type values as a valid Mercurial
   command response. These should only be encountered on pre 1.0
   Mercurial servers.

Differential Revision: https://phab.mercurial-scm.org/D3239

# httppeer.py - HTTP repository proxy classes for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[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 errno
import io
import os
import socket
import struct
import tempfile

from .i18n import _
from .thirdparty import (
    cbor,
)
from . import (
    bundle2,
    error,
    httpconnection,
    pycompat,
    statichttprepo,
    url as urlmod,
    util,
    wireproto,
    wireprotoframing,
    wireprotov2server,
)

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

def encodevalueinheaders(value, header, limit):
    """Encode a string value into multiple HTTP headers.

    ``value`` will be encoded into 1 or more HTTP headers with the names
    ``header-<N>`` where ``<N>`` is an integer starting at 1. Each header
    name + value will be at most ``limit`` bytes long.

    Returns an iterable of 2-tuples consisting of header names and
    values as native strings.
    """
    # HTTP Headers are ASCII. Python 3 requires them to be unicodes,
    # not bytes. This function always takes bytes in as arguments.
    fmt = pycompat.strurl(header) + r'-%s'
    # Note: it is *NOT* a bug that the last bit here is a bytestring
    # and not a unicode: we're just getting the encoded length anyway,
    # and using an r-string to make it portable between Python 2 and 3
    # doesn't work because then the \r is a literal backslash-r
    # instead of a carriage return.
    valuelen = limit - len(fmt % r'000') - len(': \r\n')
    result = []

    n = 0
    for i in xrange(0, len(value), valuelen):
        n += 1
        result.append((fmt % str(n), pycompat.strurl(value[i:i + valuelen])))

    return result

def _wraphttpresponse(resp):
    """Wrap an HTTPResponse with common error handlers.

    This ensures that any I/O from any consumer raises the appropriate
    error and messaging.
    """
    origread = resp.read

    class readerproxy(resp.__class__):
        def read(self, size=None):
            try:
                return origread(size)
            except httplib.IncompleteRead as e:
                # e.expected is an integer if length known or None otherwise.
                if e.expected:
                    msg = _('HTTP request error (incomplete response; '
                            'expected %d bytes got %d)') % (e.expected,
                                                           len(e.partial))
                else:
                    msg = _('HTTP request error (incomplete response)')

                raise error.PeerTransportError(
                    msg,
                    hint=_('this may be an intermittent network failure; '
                           'if the error persists, consider contacting the '
                           'network or server operator'))
            except httplib.HTTPException as e:
                raise error.PeerTransportError(
                    _('HTTP request error (%s)') % e,
                    hint=_('this may be an intermittent network failure; '
                           'if the error persists, consider contacting the '
                           'network or server operator'))

    resp.__class__ = readerproxy

class _multifile(object):
    def __init__(self, *fileobjs):
        for f in fileobjs:
            if not util.safehasattr(f, 'length'):
                raise ValueError(
                    '_multifile only supports file objects that '
                    'have a length but this one does not:', type(f), f)
        self._fileobjs = fileobjs
        self._index = 0

    @property
    def length(self):
        return sum(f.length for f in self._fileobjs)

    def read(self, amt=None):
        if amt <= 0:
            return ''.join(f.read() for f in self._fileobjs)
        parts = []
        while amt and self._index < len(self._fileobjs):
            parts.append(self._fileobjs[self._index].read(amt))
            got = len(parts[-1])
            if got < amt:
                self._index += 1
            amt -= got
        return ''.join(parts)

    def seek(self, offset, whence=os.SEEK_SET):
        if whence != os.SEEK_SET:
            raise NotImplementedError(
                '_multifile does not support anything other'
                ' than os.SEEK_SET for whence on seek()')
        if offset != 0:
            raise NotImplementedError(
                '_multifile only supports seeking to start, but that '
                'could be fixed if you need it')
        for f in self._fileobjs:
            f.seek(0)
        self._index = 0

def makev1commandrequest(ui, requestbuilder, caps, capablefn,
                         repobaseurl, cmd, args):
    """Make an HTTP request to run a command for a version 1 client.

    ``caps`` is a set of known server capabilities. The value may be
    None if capabilities are not yet known.

    ``capablefn`` is a function to evaluate a capability.

    ``cmd``, ``args``, and ``data`` define the command, its arguments, and
    raw data to pass to it.
    """
    if cmd == 'pushkey':
        args['data'] = ''
    data = args.pop('data', None)
    headers = args.pop('headers', {})

    ui.debug("sending %s command\n" % cmd)
    q = [('cmd', cmd)]
    headersize = 0
    varyheaders = []
    # Important: don't use self.capable() here or else you end up
    # with infinite recursion when trying to look up capabilities
    # for the first time.
    postargsok = caps is not None and 'httppostargs' in caps

    # Send arguments via POST.
    if postargsok and args:
        strargs = urlreq.urlencode(sorted(args.items()))
        if not data:
            data = strargs
        else:
            if isinstance(data, bytes):
                i = io.BytesIO(data)
                i.length = len(data)
                data = i
            argsio = io.BytesIO(strargs)
            argsio.length = len(strargs)
            data = _multifile(argsio, data)
        headers[r'X-HgArgs-Post'] = len(strargs)
    elif args:
        # Calling self.capable() can infinite loop if we are calling
        # "capabilities". But that command should never accept wire
        # protocol arguments. So this should never happen.
        assert cmd != 'capabilities'
        httpheader = capablefn('httpheader')
        if httpheader:
            headersize = int(httpheader.split(',', 1)[0])

        # Send arguments via HTTP headers.
        if headersize > 0:
            # The headers can typically carry more data than the URL.
            encargs = urlreq.urlencode(sorted(args.items()))
            for header, value in encodevalueinheaders(encargs, 'X-HgArg',
                                                      headersize):
                headers[header] = value
                varyheaders.append(header)
        # Send arguments via query string (Mercurial <1.9).
        else:
            q += sorted(args.items())

    qs = '?%s' % urlreq.urlencode(q)
    cu = "%s%s" % (repobaseurl, qs)
    size = 0
    if util.safehasattr(data, 'length'):
        size = data.length
    elif data is not None:
        size = len(data)
    if data is not None and r'Content-Type' not in headers:
        headers[r'Content-Type'] = r'application/mercurial-0.1'

    # Tell the server we accept application/mercurial-0.2 and multiple
    # compression formats if the server is capable of emitting those
    # payloads.
    protoparams = {'partial-pull'}

    mediatypes = set()
    if caps is not None:
        mt = capablefn('httpmediatype')
        if mt:
            protoparams.add('0.1')
            mediatypes = set(mt.split(','))

    if '0.2tx' in mediatypes:
        protoparams.add('0.2')

    if '0.2tx' in mediatypes and capablefn('compression'):
        # We /could/ compare supported compression formats and prune
        # non-mutually supported or error if nothing is mutually supported.
        # For now, send the full list to the server and have it error.
        comps = [e.wireprotosupport().name for e in
                 util.compengines.supportedwireengines(util.CLIENTROLE)]
        protoparams.add('comp=%s' % ','.join(comps))

    if protoparams:
        protoheaders = encodevalueinheaders(' '.join(sorted(protoparams)),
                                            'X-HgProto',
                                            headersize or 1024)
        for header, value in protoheaders:
            headers[header] = value
            varyheaders.append(header)

    if varyheaders:
        headers[r'Vary'] = r','.join(varyheaders)

    req = requestbuilder(pycompat.strurl(cu), data, headers)

    if data is not None:
        ui.debug("sending %d bytes\n" % size)
        req.add_unredirected_header(r'Content-Length', r'%d' % size)

    return req, cu, qs

def sendrequest(ui, opener, req):
    """Send a prepared HTTP request.

    Returns the response object.
    """
    if (ui.debugflag
        and ui.configbool('devel', 'debug.peer-request')):
        dbg = ui.debug
        line = 'devel-peer-request: %s\n'
        dbg(line % '%s %s' % (req.get_method(), req.get_full_url()))
        hgargssize = None

        for header, value in sorted(req.header_items()):
            if header.startswith('X-hgarg-'):
                if hgargssize is None:
                    hgargssize = 0
                hgargssize += len(value)
            else:
                dbg(line % '  %s %s' % (header, value))

        if hgargssize is not None:
            dbg(line % '  %d bytes of commands arguments in headers'
                % hgargssize)

        if req.has_data():
            data = req.get_data()
            length = getattr(data, 'length', None)
            if length is None:
                length = len(data)
            dbg(line % '  %d bytes of data' % length)

        start = util.timer()

    try:
        res = opener.open(req)
    except urlerr.httperror as inst:
        if inst.code == 401:
            raise error.Abort(_('authorization failed'))
        raise
    except httplib.HTTPException as inst:
        ui.debug('http error requesting %s\n' %
                 util.hidepassword(req.get_full_url()))
        ui.traceback()
        raise IOError(None, inst)
    finally:
        if ui.configbool('devel', 'debug.peer-request'):
            dbg(line % '  finished in %.4f seconds (%s)'
                % (util.timer() - start, res.code))

    # Insert error handlers for common I/O failures.
    _wraphttpresponse(res)

    return res

def parsev1commandresponse(ui, baseurl, requrl, qs, resp, compressible):
    # record the url we got redirected to
    respurl = pycompat.bytesurl(resp.geturl())
    if respurl.endswith(qs):
        respurl = respurl[:-len(qs)]
    if baseurl.rstrip('/') != respurl.rstrip('/'):
        if not ui.quiet:
            ui.warn(_('real URL is %s\n') % respurl)

    try:
        proto = pycompat.bytesurl(resp.getheader(r'content-type', r''))
    except AttributeError:
        proto = pycompat.bytesurl(resp.headers.get(r'content-type', r''))

    safeurl = util.hidepassword(baseurl)
    if proto.startswith('application/hg-error'):
        raise error.OutOfBandError(resp.read())

    # Pre 1.0 versions of Mercurial used text/plain and
    # application/hg-changegroup. We don't support such old servers.
    if not proto.startswith('application/mercurial-'):
        ui.debug("requested URL: '%s'\n" % util.hidepassword(requrl))
        raise error.RepoError(
            _("'%s' does not appear to be an hg repository:\n"
              "---%%<--- (%s)\n%s\n---%%<---\n")
            % (safeurl, proto or 'no content-type', resp.read(1024)))

    try:
        version = proto.split('-', 1)[1]
        version_info = tuple([int(n) for n in version.split('.')])
    except ValueError:
        raise error.RepoError(_("'%s' sent a broken Content-Type "
                                "header (%s)") % (safeurl, proto))

    # TODO consider switching to a decompression reader that uses
    # generators.
    if version_info == (0, 1):
        if compressible:
            resp = util.compengines['zlib'].decompressorreader(resp)

    elif version_info == (0, 2):
        # application/mercurial-0.2 always identifies the compression
        # engine in the payload header.
        elen = struct.unpack('B', resp.read(1))[0]
        ename = resp.read(elen)
        engine = util.compengines.forwiretype(ename)

        resp = engine.decompressorreader(resp)
    else:
        raise error.RepoError(_("'%s' uses newer protocol %s") %
                              (safeurl, version))

    return respurl, resp

class httppeer(wireproto.wirepeer):
    def __init__(self, ui, path, url, opener, requestbuilder, caps):
        self.ui = ui
        self._path = path
        self._url = url
        self._caps = caps
        self._urlopener = opener
        self._requestbuilder = requestbuilder

    def __del__(self):
        for h in self._urlopener.handlers:
            h.close()
            getattr(h, "close_all", lambda: None)()

    # Begin of ipeerconnection interface.

    def url(self):
        return self._path

    def local(self):
        return None

    def peer(self):
        return self

    def canpush(self):
        return True

    def close(self):
        pass

    # End of ipeerconnection interface.

    # Begin of ipeercommands interface.

    def capabilities(self):
        return self._caps

    # End of ipeercommands interface.

    # look up capabilities only when needed

    def _callstream(self, cmd, _compressible=False, **args):
        args = pycompat.byteskwargs(args)

        req, cu, qs = makev1commandrequest(self.ui, self._requestbuilder,
                                           self._caps, self.capable,
                                           self._url, cmd, args)

        resp = sendrequest(self.ui, self._urlopener, req)

        self._url, resp = parsev1commandresponse(self.ui, self._url, cu, qs,
                                                 resp, _compressible)

        return resp

    def _call(self, cmd, **args):
        fp = self._callstream(cmd, **args)
        try:
            return fp.read()
        finally:
            # if using keepalive, allow connection to be reused
            fp.close()

    def _callpush(self, cmd, cg, **args):
        # have to stream bundle to a temp file because we do not have
        # http 1.1 chunked transfer.

        types = self.capable('unbundle')
        try:
            types = types.split(',')
        except AttributeError:
            # servers older than d1b16a746db6 will send 'unbundle' as a
            # boolean capability. They only support headerless/uncompressed
            # bundles.
            types = [""]
        for x in types:
            if x in bundle2.bundletypes:
                type = x
                break

        tempname = bundle2.writebundle(self.ui, cg, None, type)
        fp = httpconnection.httpsendfile(self.ui, tempname, "rb")
        headers = {r'Content-Type': r'application/mercurial-0.1'}

        try:
            r = self._call(cmd, data=fp, headers=headers, **args)
            vals = r.split('\n', 1)
            if len(vals) < 2:
                raise error.ResponseError(_("unexpected response:"), r)
            return vals
        except urlerr.httperror:
            # Catch and re-raise these so we don't try and treat them
            # like generic socket errors. They lack any values in
            # .args on Python 3 which breaks our socket.error block.
            raise
        except socket.error as err:
            if err.args[0] in (errno.ECONNRESET, errno.EPIPE):
                raise error.Abort(_('push failed: %s') % err.args[1])
            raise error.Abort(err.args[1])
        finally:
            fp.close()
            os.unlink(tempname)

    def _calltwowaystream(self, cmd, fp, **args):
        fh = None
        fp_ = None
        filename = None
        try:
            # dump bundle to disk
            fd, filename = tempfile.mkstemp(prefix="hg-bundle-", suffix=".hg")
            fh = os.fdopen(fd, r"wb")
            d = fp.read(4096)
            while d:
                fh.write(d)
                d = fp.read(4096)
            fh.close()
            # start http push
            fp_ = httpconnection.httpsendfile(self.ui, filename, "rb")
            headers = {r'Content-Type': r'application/mercurial-0.1'}
            return self._callstream(cmd, data=fp_, headers=headers, **args)
        finally:
            if fp_ is not None:
                fp_.close()
            if fh is not None:
                fh.close()
                os.unlink(filename)

    def _callcompressable(self, cmd, **args):
        return self._callstream(cmd, _compressible=True, **args)

    def _abort(self, exception):
        raise exception

# TODO implement interface for version 2 peers
class httpv2peer(object):
    def __init__(self, ui, repourl, opener):
        self.ui = ui

        if repourl.endswith('/'):
            repourl = repourl[:-1]

        self.url = repourl
        self._opener = opener
        # This is an its own attribute to facilitate extensions overriding
        # the default type.
        self._requestbuilder = urlreq.request

    def close(self):
        pass

    # TODO require to be part of a batched primitive, use futures.
    def _call(self, name, **args):
        """Call a wire protocol command with arguments."""

        # Having this early has a side-effect of importing wireprotov2server,
        # which has the side-effect of ensuring commands are registered.

        # TODO modify user-agent to reflect v2.
        headers = {
            r'Accept': wireprotov2server.FRAMINGTYPE,
            r'Content-Type': wireprotov2server.FRAMINGTYPE,
        }

        # TODO permissions should come from capabilities results.
        permission = wireproto.commandsv2[name].permission
        if permission not in ('push', 'pull'):
            raise error.ProgrammingError('unknown permission type: %s' %
                                         permission)

        permission = {
            'push': 'rw',
            'pull': 'ro',
        }[permission]

        url = '%s/api/%s/%s/%s' % (self.url, wireprotov2server.HTTPV2,
                                   permission, name)

        # TODO this should be part of a generic peer for the frame-based
        # protocol.
        reactor = wireprotoframing.clientreactor(hasmultiplesend=False,
                                                 buffersends=True)

        request, action, meta = reactor.callcommand(name, args)
        assert action == 'noop'

        action, meta = reactor.flushcommands()
        assert action == 'sendframes'

        body = b''.join(map(bytes, meta['framegen']))
        req = self._requestbuilder(pycompat.strurl(url), body, headers)
        req.add_unredirected_header(r'Content-Length', r'%d' % len(body))

        # TODO unify this code with httppeer.
        try:
            res = self._opener.open(req)
        except urlerr.httperror as e:
            if e.code == 401:
                raise error.Abort(_('authorization failed'))

            raise
        except httplib.HTTPException as e:
            self.ui.traceback()
            raise IOError(None, e)

        # TODO validate response type, wrap response to handle I/O errors.
        # TODO more robust frame receiver.
        results = []

        while True:
            frame = wireprotoframing.readframe(res)
            if frame is None:
                break

            self.ui.note(_('received %r\n') % frame)

            action, meta = reactor.onframerecv(frame)

            if action == 'responsedata':
                if meta['cbor']:
                    payload = util.bytesio(meta['data'])

                    decoder = cbor.CBORDecoder(payload)
                    while payload.tell() + 1 < len(meta['data']):
                        results.append(decoder.decode())
                else:
                    results.append(meta['data'])
            else:
                error.ProgrammingError('unhandled action: %s' % action)

        return results

def performhandshake(ui, url, opener, requestbuilder):
    # The handshake is a request to the capabilities command.

    caps = None
    def capable(x):
        raise error.ProgrammingError('should not be called')

    req, requrl, qs = makev1commandrequest(ui, requestbuilder, caps,
                                           capable, url, 'capabilities',
                                           {})

    resp = sendrequest(ui, opener, req)

    respurl, resp = parsev1commandresponse(ui, url, requrl, qs, resp,
                                           compressible=False)

    try:
        rawcaps = resp.read()
    finally:
        resp.close()

    return respurl, set(rawcaps.split())

def makepeer(ui, path, opener=None, requestbuilder=urlreq.request):
    """Construct an appropriate HTTP peer instance.

    ``opener`` is an ``url.opener`` that should be used to establish
    connections, perform HTTP requests.

    ``requestbuilder`` is the type used for constructing HTTP requests.
    It exists as an argument so extensions can override the default.
    """
    u = util.url(path)
    if u.query or u.fragment:
        raise error.Abort(_('unsupported URL component: "%s"') %
                          (u.query or u.fragment))

    # urllib cannot handle URLs with embedded user or passwd.
    url, authinfo = u.authinfo()
    ui.debug('using %s\n' % url)

    opener = opener or urlmod.opener(ui, authinfo)

    respurl, caps = performhandshake(ui, url, opener, requestbuilder)

    return httppeer(ui, path, respurl, opener, requestbuilder, caps)

def instance(ui, path, create):
    if create:
        raise error.Abort(_('cannot create new http repository'))
    try:
        if path.startswith('https:') and not urlmod.has_https:
            raise error.Abort(_('Python support for SSL and HTTPS '
                                'is not installed'))

        inst = makepeer(ui, path)

        return inst
    except error.RepoError as httpexception:
        try:
            r = statichttprepo.instance(ui, "static-" + path, create)
            ui.note(_('(falling back to static-http)\n'))
            return r
        except error.RepoError:
            raise httpexception # use the original http RepoError instead