mercurial/httppeer.py

config: explicitly track the use of the standard default value

We introduce a small object used to detect that no specific default value has
been passed to 'ui.config'. We need this explicit special value since "None" is
a valid and common default value.

The end goal here is to make progress on a centralised and explicit declaration
of the available config option. A first good usecase for this are "default"
value.  Before starting looking further down this alley we needs to rework the
handling of default value in the 'ui' object to have all configxyz methods going
through the same logic. This is the first changeset on this trek.

# 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 os
import socket
import struct
import tempfile

from .i18n import _
from .node import nullid
from . import (
    bundle2,
    error,
    httpconnection,
    pycompat,
    statichttprepo,
    url,
    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.
    """
    fmt = header + '-%s'
    valuelen = limit - len(fmt % '000') - len(': \r\n')
    result = []

    n = 0
    for i in xrange(0, len(value), valuelen):
        n += 1
        result.append((fmt % str(n), 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 httppeer(wireproto.wirepeer):
    def __init__(self, ui, path):
        self.path = path
        self.caps = None
        self.handler = None
        self.urlopener = None
        self.requestbuilder = None
        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
        self._url, authinfo = u.authinfo()

        self.ui = ui
        self.ui.debug('using %s\n' % self._url)

        self.urlopener = url.opener(ui, authinfo)
        self.requestbuilder = urlreq.request

    def __del__(self):
        urlopener = getattr(self, 'urlopener', None)
        if urlopener:
            for h in urlopener.handlers:
                h.close()
                getattr(h, "close_all", lambda : None)()

    def url(self):
        return self.path

    # look up capabilities only when needed

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

    def _capabilities(self):
        if self.caps is None:
            try:
                self._fetchcaps()
            except error.RepoError:
                self.caps = set()
            self.ui.debug('capabilities: %s\n' %
                          (' '.join(self.caps or ['none'])))
        return self.caps

    def lock(self):
        raise error.Abort(_('operation not supported over http'))

    def _callstream(self, cmd, _compressible=False, **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
        # TODO: support for httppostargs when data is a file-like
        # object rather than a basestring
        canmungedata = not data or isinstance(data, basestring)
        if postargsok and canmungedata:
            strargs = urlreq.urlencode(sorted(args.items()))
            if strargs:
                if not data:
                    data = strargs
                elif isinstance(data, basestring):
                    data = strargs + data
                headers['X-HgArgs-Post'] = len(strargs)
        else:
            if len(args) > 0:
                httpheader = self.capable('httpheader')
                if httpheader:
                    headersize = int(httpheader.split(',', 1)[0])
            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)
            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 size and self.ui.configbool('ui', 'usehttp2', False):
            headers['Expect'] = '100-Continue'
            headers['X-HgHttp2'] = '1'
        if data is not None and 'Content-Type' not in headers:
            headers['Content-Type'] = '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['Vary'] = ','.join(varyheaders)

        req = self.requestbuilder(cu, data, headers)

        if data is not None:
            self.ui.debug("sending %s bytes\n" % size)
            req.add_unredirected_header('Content-Length', '%d' % size)
        try:
            resp = self.urlopener.open(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 = 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 = resp.getheader('content-type')
        except AttributeError:
            proto = resp.headers.get('content-type', '')

        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 = {'Content-Type': '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 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, pycompat.sysstr("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 = {'Content-Type': '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

class httpspeer(httppeer):
    def __init__(self, ui, path):
        if not url.has_https:
            raise error.Abort(_('Python support for SSL and HTTPS '
                               'is not installed'))
        httppeer.__init__(self, ui, path)

def instance(ui, path, create):
    if create:
        raise error.Abort(_('cannot create new http repository'))
    try:
        if path.startswith('https:'):
            inst = httpspeer(ui, path)
        else:
            inst = httppeer(ui, path)
        try:
            # Try to do useful work when checking compatibility.
            # Usually saves a roundtrip since we want the caps anyway.
            inst._fetchcaps()
        except error.RepoError:
            # No luck, try older compatibility check.
            inst.between([(nullid, nullid)])
        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