mercurial/httppeer.py

zope: force module import by importing symbols

Previously, we tried to import a module and handle the ImportError.
Our lazy module importer doesn't verify the module exists and returns
a dummy object representing the module. Only once we attempt to load
a symbol in the module does the ImportError get raises.

This means that simple imports inside `try..except ImportError` don't
detect missing modules.

This commit changes imports in zope.interface to access symbols, thus
forcing module load and triggering ImportError.

This fixes zope.interface for pure builds.

Differential Revision: https://phab.mercurial-scm.org/D2980

# 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 . import (
    bundle2,
    error,
    httpconnection,
    pycompat,
    statichttprepo,
    url as urlmod,
    util,
    wireproto,
)

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

class httppeer(wireproto.wirepeer):
    def __init__(self, ui, path, url, opener):
        self._ui = ui
        self._path = path
        self._url = url
        self._caps = None
        self._urlopener = opener
        # This is an its own attribute to facilitate extensions overriding
        # the default type.
        self._requestbuilder = urlreq.request

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

    def _openurl(self, req):
        if (self._ui.debugflag
            and self._ui.configbool('devel', 'debug.peer-request')):
            dbg = self._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()

        ret = self._urlopener.open(req)
        if self._ui.configbool('devel', 'debug.peer-request'):
            dbg(line % '  finished in %.4f seconds (%s)'
                % (util.timer() - start, ret.code))
        return ret

    # Begin of _basepeer interface.

    @util.propertycache
    def ui(self):
        return self._ui

    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 _basepeer interface.

    # Begin of _basewirepeer interface.

    def capabilities(self):
        # self._fetchcaps() should have been called as part of peer
        # handshake. So self._caps should always be set.
        assert self._caps is not None
        return self._caps

    # End of _basewirepeer interface.

    # look up capabilities only when needed

    def _fetchcaps(self):
        self._caps = set(self._call('capabilities').split())

    def _callstream(self, cmd, _compressible=False, **args):
        args = pycompat.byteskwargs(args)
        if cmd == 'pushkey':
            args['data'] = ''
        data = args.pop('data', None)
        headers = args.pop('headers', {})

        self.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 = self._caps is not None and 'httppostargs' in self._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 = self.capable('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" % (self._url, 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 = []

        mediatypes = set()
        if self._caps is not None:
            mt = self.capable('httpmediatype')
            if mt:
                protoparams.append('0.1')
                mediatypes = set(mt.split(','))

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

        if '0.2tx' in mediatypes and self.capable('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.append('comp=%s' % ','.join(comps))

        if protoparams:
            protoheaders = encodevalueinheaders(' '.join(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 = self._requestbuilder(pycompat.strurl(cu), data, headers)

        if data is not None:
            self.ui.debug("sending %d bytes\n" % size)
            req.add_unredirected_header(r'Content-Length', r'%d' % size)
        try:
            resp = self._openurl(req)
        except urlerr.httperror as inst:
            if inst.code == 401:
                raise error.Abort(_('authorization failed'))
            raise
        except httplib.HTTPException as inst:
            self.ui.debug('http error while sending %s command\n' % cmd)
            self.ui.traceback()
            raise IOError(None, inst)

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

        # record the url we got redirected to
        resp_url = pycompat.bytesurl(resp.geturl())
        if resp_url.endswith(qs):
            resp_url = resp_url[:-len(qs)]
        if self._url.rstrip('/') != resp_url.rstrip('/'):
            if not self.ui.quiet:
                self.ui.warn(_('real URL is %s\n') % resp_url)
        self._url = resp_url
        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(self._url)
        if proto.startswith('application/hg-error'):
            raise error.OutOfBandError(resp.read())
        # accept old "text/plain" and "application/hg-changegroup" for now
        if not (proto.startswith('application/mercurial-') or
                (proto.startswith('text/plain')
                 and not resp.headers.get('content-length')) or
                proto.startswith('application/hg-changegroup')):
            self.ui.debug("requested URL: '%s'\n" % util.hidepassword(cu))
            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)))

        if proto.startswith('application/mercurial-'):
            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:
                    return util.compengines['zlib'].decompressorreader(resp)
                return 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)
                return engine.decompressorreader(resp)
            else:
                raise error.RepoError(_("'%s' uses newer protocol %s") %
                                      (safeurl, version))

        if _compressible:
            return util.compengines['zlib'].decompressorreader(resp)

        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

def makepeer(ui, path):
    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 = urlmod.opener(ui, authinfo)

    return httppeer(ui, path, url, opener)

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)
        inst._fetchcaps()

        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