mercurial/httppeer.py

sslutil: add support for clients to set TLSv1.3 as the minimum protocol

AFAICT, all of the TLS versions are supported by the server without doing any
explicit work, and there's only a `devel` config to specify an exact version on
the server side.  Clients would also use TLSv1.3 if available, but this prevents
the server from negotiating down.  This also causes "tls1.3" to be listed in
`hg debuginstall`, even though it was previously supported (if the Python
intepreter supported it- IDK if there's a good way to proactively test for and
show future protocols without requiring manual updates like this).

The v1.3 tests are nested inside the v1.2 tests for simplicity.  The v1.2 blocks
already assume v1.0 and v1.1 support, so this seems reasonable for now.  If/when
the older protocols start getting dropped, this will have to be reworked anyway.

# httppeer.py - HTTP repository proxy classes for mercurial
#
# Copyright 2005, 2006 Olivia 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 annotations

import errno
import io
import os
import socket
import struct

from concurrent import futures
from .i18n import _
from . import (
    bundle2,
    error,
    httpconnection,
    pycompat,
    statichttprepo,
    url as urlmod,
    util,
    wireprotov1peer,
)
from .utils import urlutil

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 % '000') - len(b': \r\n')
    result = []

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

    return result


class _multifile:
    def __init__(self, *fileobjs):
        for f in fileobjs:
            if not hasattr(f, 'length'):
                raise ValueError(
                    b'_multifile only supports file objects that '
                    b'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 b''.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 b''.join(parts)

    def seek(self, offset, whence=os.SEEK_SET):
        if whence != os.SEEK_SET:
            raise NotImplementedError(
                b'_multifile does not support anything other'
                b' than os.SEEK_SET for whence on seek()'
            )
        if offset != 0:
            raise NotImplementedError(
                b'_multifile only supports seeking to start, but that '
                b'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,
    remotehidden=False,
):
    """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 == b'pushkey':
        args[b'data'] = b''
    data = args.pop(b'data', None)
    headers = args.pop(b'headers', {})

    ui.debug(b"sending %s command\n" % cmd)
    q = [(b'cmd', cmd)]
    if remotehidden:
        q.append(('access-hidden', '1'))
    headersize = 0
    # 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 b'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['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 != b'capabilities'
        httpheader = capablefn(b'httpheader')
        if httpheader:
            headersize = int(httpheader.split(b',', 1)[0])

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

    qs = b'?%s' % urlreq.urlencode(q)
    cu = b"%s%s" % (repobaseurl, qs)
    size = 0
    if hasattr(data, 'length'):
        size = data.length
    elif data is not None:
        size = len(data)
    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.
    # Note: Keep this set empty by default, as client advertisement of
    # protocol parameters should only occur after the handshake.
    protoparams = set()

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

        protoparams.add(b'partial-pull')

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

    if b'0.2tx' in mediatypes and capablefn(b'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(b'comp=%s' % b','.join(comps))

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

    varyheaders = []
    for header in headers:
        if header.lower().startswith('x-hg'):
            varyheaders.append(header)

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

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

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

    return req, cu, qs


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

    Returns the response object.
    """
    dbg = ui.debug
    line = b'devel-peer-request: %s\n'

    if ui.debugflag and ui.configbool(b'devel', b'debug.peer-request'):
        dbg(
            line
            % b'%s %s'
            % (
                pycompat.bytesurl(req.get_method()),
                pycompat.bytesurl(req.get_full_url()),
            )
        )
        hgargssize = None

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

        if hgargssize is not None:
            dbg(
                line
                % b'  %d bytes of commands arguments in headers'
                % hgargssize
            )
        data = req.data
        if data is not None:
            length = getattr(data, 'length', None)
            if length is None:
                length = len(data)
            dbg(line % b'  %d bytes of data' % length)

        start = util.timer()

    res = None
    try:
        res = opener.open(req)
    except urlerr.httperror as inst:
        if inst.code == 401:
            raise error.Abort(_(b'authorization failed'))
        raise
    except httplib.HTTPException as inst:
        ui.debug(
            b'http error requesting %s\n'
            % urlutil.hidepassword(req.get_full_url())
        )
        ui.traceback()
        raise IOError(None, inst)
    finally:
        if ui.debugflag and ui.configbool(b'devel', b'debug.peer-request'):
            code = res.code if res else -1
            dbg(
                line
                % b'  finished in %.4f seconds (%d)'
                % (util.timer() - start, code)
            )

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

    return res


class RedirectedRepoError(error.RepoError):
    def __init__(self, msg, respurl):
        super(RedirectedRepoError, self).__init__(msg)
        self.respurl = respurl


def parsev1commandresponse(ui, baseurl, requrl, qs, resp, compressible):
    # record the url we got redirected to
    redirected = False
    respurl = pycompat.bytesurl(resp.geturl())
    if respurl.endswith(qs):
        respurl = respurl[: -len(qs)]
        qsdropped = False
    else:
        qsdropped = True

    if baseurl.rstrip(b'/') != respurl.rstrip(b'/'):
        redirected = True
        if not ui.quiet:
            ui.warn(_(b'real URL is %s\n') % respurl)

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

    safeurl = urlutil.hidepassword(baseurl)
    if proto.startswith(b'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(b'application/mercurial-'):
        ui.debug(b"requested URL: '%s'\n" % urlutil.hidepassword(requrl))
        msg = _(
            b"'%s' does not appear to be an hg repository:\n"
            b"---%%<--- (%s)\n%s\n---%%<---\n"
        ) % (safeurl, proto or b'no content-type', resp.read(1024))

        # Some servers may strip the query string from the redirect. We
        # raise a special error type so callers can react to this specially.
        if redirected and qsdropped:
            raise RedirectedRepoError(msg, respurl)
        else:
            raise error.RepoError(msg)

    try:
        subtype = proto.split(b'-', 1)[1]

        version_info = tuple([int(n) for n in subtype.split(b'.')])
    except ValueError:
        raise error.RepoError(
            _(b"'%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[b'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'B', util.readexactly(resp, 1))[0]
        ename = util.readexactly(resp, elen)
        engine = util.compengines.forwiretype(ename)

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

    return respurl, proto, resp


class httppeer(wireprotov1peer.wirepeer):
    def __init__(
        self, ui, path, url, opener, requestbuilder, caps, remotehidden=False
    ):
        super().__init__(ui, path=path, remotehidden=remotehidden)
        self._url = url
        self._caps = caps
        self.limitedarguments = caps is not None and b'httppostargs' not in caps
        self._urlopener = opener
        self._requestbuilder = requestbuilder
        self._remotehidden = remotehidden

    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.loc

    def local(self):
        return None

    def canpush(self):
        return True

    def close(self):
        try:
            reqs, sent, recv = (
                self._urlopener.requestscount,
                self._urlopener.sentbytescount,
                self._urlopener.receivedbytescount,
            )
        except AttributeError:
            return
        self.ui.note(
            _(
                b'(sent %d HTTP requests and %d bytes; '
                b'received %d bytes in responses)\n'
            )
            % (reqs, sent, recv)
        )

    # End of ipeerconnection interface.

    # Begin of ipeercommands interface.

    def capabilities(self):
        return self._caps

    def _finish_inline_clone_bundle(self, stream):
        # HTTP streams must hit the end to process the last empty
        # chunk of Chunked-Encoding so the connection can be reused.
        chunk = stream.read(1)
        if chunk:
            self._abort(error.ResponseError(_(b"unexpected response:"), chunk))

    # End of ipeercommands interface.

    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,
            self._remotehidden,
        )

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

        self._url, ct, 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(b'unbundle')
        try:
            types = types.split(b',')
        except AttributeError:
            # servers older than d1b16a746db6 will send 'unbundle' as a
            # boolean capability. They only support headerless/uncompressed
            # bundles.
            types = [b""]

        type = b""

        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, b"rb")
        headers = {'Content-Type': 'application/mercurial-0.1'}

        try:
            r = self._call(cmd, data=fp, headers=headers, **args)
            vals = r.split(b'\n', 1)
            if len(vals) < 2:
                raise error.ResponseError(_(b"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(_(b'push failed: %s') % err.args[1])
            raise error.Abort(err.args[1])
        finally:
            fp.close()
            os.unlink(tempname)

    def _calltwowaystream(self, cmd, fp, **args):
        # dump bundle to disk
        fd, filename = pycompat.mkstemp(prefix=b"hg-bundle-", suffix=b".hg")
        try:
            with os.fdopen(fd, "wb") as fh:
                d = fp.read(4096)
                while d:
                    fh.write(d)
                    d = fp.read(4096)
            # start http push
            with httpconnection.httpsendfile(self.ui, filename, b"rb") as fp_:
                headers = {'Content-Type': 'application/mercurial-0.1'}
                return self._callstream(cmd, data=fp_, headers=headers, **args)
        finally:
            os.unlink(filename)

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

    def _abort(self, exception):
        raise exception


class queuedcommandfuture(futures.Future):
    """Wraps result() on command futures to trigger submission on call."""

    def result(self, timeout=None):
        if self.done():
            return futures.Future.result(self, timeout)

        self._peerexecutor.sendcommands()

        # sendcommands() will restore the original __class__ and self.result
        # will resolve to Future.result.
        return self.result(timeout)


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

    caps = None

    def capable(x):
        raise error.ProgrammingError(b'should not be called')

    args = {}

    req, requrl, qs = makev1commandrequest(
        ui, requestbuilder, caps, capable, url, b'capabilities', args
    )
    resp = sendrequest(ui, opener, req)

    # The server may redirect us to the repo root, stripping the
    # ?cmd=capabilities query string from the URL. The server would likely
    # return HTML in this case and ``parsev1commandresponse()`` would raise.
    # We catch this special case and re-issue the capabilities request against
    # the new URL.
    #
    # We should ideally not do this, as a redirect that drops the query
    # string from the URL is arguably a server bug. (Garbage in, garbage out).
    # However,  Mercurial clients for several years appeared to handle this
    # issue without behavior degradation. And according to issue 5860, it may
    # be a longstanding bug in some server implementations. So we allow a
    # redirect that drops the query string to "just work."
    try:
        respurl, ct, resp = parsev1commandresponse(
            ui, url, requrl, qs, resp, compressible=False
        )
    except RedirectedRepoError as e:
        req, requrl, qs = makev1commandrequest(
            ui, requestbuilder, caps, capable, e.respurl, b'capabilities', args
        )
        resp = sendrequest(ui, opener, req)
        respurl, ct, resp = parsev1commandresponse(
            ui, url, requrl, qs, resp, compressible=False
        )

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

    if not ct.startswith(b'application/mercurial-'):
        raise error.ProgrammingError(b'unexpected content-type: %s' % ct)

    info = {b'v1capabilities': set(rawdata.split())}

    return respurl, info


def _make_peer(
    ui, path, opener=None, requestbuilder=urlreq.request, remotehidden=False
):
    """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.
    """
    if path.url.query or path.url.fragment:
        msg = _(b'unsupported URL component: "%s"')
        msg %= path.url.query or path.url.fragment
        raise error.Abort(msg)

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

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

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

    return httppeer(
        ui,
        path,
        respurl,
        opener,
        requestbuilder,
        info[b'v1capabilities'],
        remotehidden=remotehidden,
    )


def make_peer(
    ui, path, create, intents=None, createopts=None, remotehidden=False
):
    if create:
        raise error.Abort(_(b'cannot create new http repository'))
    try:
        if path.url.scheme == b'https' and not urlmod.has_https:
            raise error.Abort(
                _(b'Python support for SSL and HTTPS is not installed')
            )

        inst = _make_peer(ui, path, remotehidden=remotehidden)

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