annotate mercurial/hgweb/server.py @ 37150:a2566597acb5

lfs: add basic routing for the server side wire protocol processing

The recent hgweb refactoring yielded a clean point to wrap a function that could
handle this, so I moved the routing for this out of the core.  While not an hg
wire protocol, this seems logically close enough.  For now, these handlers do
nothing other than check permissions.

The protocol requires support for PUT requests, so that has been added to the
core, and funnels into the same handler as GET and POST.  The permission
checking code was assuming that anything not checking 'pull' or None ops should
be using POST.  But that breaks the upload check if it checks 'push'.  So I
invented a new 'upload' permission, and used it to avoid the mandate to POST.  A
function wrap point could be added, but security code should probably stay
grouped together.  Given that anything not 'pull' or None was requiring POST,
the comment on hgweb.common.permhooks is probably wrong- there is no 'read'.

The rationale for the URIs is that the spec for the Batch API[1] defines the URL
as the LFS server url + '/objects/batch'.  The default git URLs are:

    Git remote: https://git-server.com/foo/bar
    LFS server: https://git-server.com/foo/bar.git/info/lfs
    Batch API: https://git-server.com/foo/bar.git/info/lfs/objects/batch

'.git/' seems like it's not something a user would normally track.  If we adhere
to how git defines the URLs, then the hg-git extension should be able to talk to
a git based server without any additional work.

The URI for the transfer requests starts with '.hg/' to ensure that there are no
conflicts with tracked files.  Since these are handed out by the Batch API, we
can change this at any point in the future.  (Specifically, it might be a good
idea to use something under the proposed /api/ namespace.)  In any case, no
files are stored at these locations in the repository directory.

I started a new module for this because it seems like a good idea to keep all of
the security sensitive server side code together.  There's also an issue with
`hg verify` in that it will want to download *all* blobs in order to run.
Sadly, there's no way in the protocol to ask the server to verify the content of
a blob it may have.  (The verify action is for storing files on a 3rd party
server, and then informing the LFS server when that completes.)  So we may end
up implementing a custom transfer adapter that simply indicates if the blobs are
valid, and fall back to basic transfers for non-hg servers.  In other words,
this code is likely to get bigger before this is made non-experimental.

[1] https://github.com/git-lfs/git-lfs/blob/master/docs/api/batch.md

# hgweb/server.py - The standalone hg web server.
#
# Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
# Copyright 2005-2007 Matt Mackall <[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 sys
import traceback
import wsgiref.validate

from ..i18n import _

from .. import (
    encoding,
    error,
    pycompat,
    util,
)

httpservermod = util.httpserver
socketserver = util.socketserver
urlerr = util.urlerr
urlreq = util.urlreq

from . import (
    common,
)

def _splitURI(uri):
    """Return path and query that has been split from uri

    Just like CGI environment, the path is unquoted, the query is
    not.
    """
    if r'?' in uri:
        path, query = uri.split(r'?', 1)
    else:
        path, query = uri, r''
    return urlreq.unquote(path), query

class _error_logger(object):
    def __init__(self, handler):
        self.handler = handler
    def flush(self):
        pass
    def write(self, str):
        self.writelines(str.split('\n'))
    def writelines(self, seq):
        for msg in seq:
            self.handler.log_error("HG error:  %s", msg)

class _httprequesthandler(httpservermod.basehttprequesthandler):

    url_scheme = 'http'

    @staticmethod
    def preparehttpserver(httpserver, ui):
        """Prepare .socket of new HTTPServer instance"""

    def __init__(self, *args, **kargs):
        self.protocol_version = r'HTTP/1.1'
        httpservermod.basehttprequesthandler.__init__(self, *args, **kargs)

    def _log_any(self, fp, format, *args):
        fp.write(pycompat.sysbytes(
            r"%s - - [%s] %s" % (self.client_address[0],
                                 self.log_date_time_string(),
                                 format % args)) + '\n')
        fp.flush()

    def log_error(self, format, *args):
        self._log_any(self.server.errorlog, format, *args)

    def log_message(self, format, *args):
        self._log_any(self.server.accesslog, format, *args)

    def log_request(self, code=r'-', size=r'-'):
        xheaders = []
        if util.safehasattr(self, 'headers'):
            xheaders = [h for h in self.headers.items()
                        if h[0].startswith(r'x-')]
        self.log_message(r'"%s" %s %s%s',
                         self.requestline, str(code), str(size),
                         r''.join([r' %s:%s' % h for h in sorted(xheaders)]))

    def do_write(self):
        try:
            self.do_hgweb()
        except socket.error as inst:
            if inst[0] != errno.EPIPE:
                raise

    def do_POST(self):
        try:
            self.do_write()
        except Exception:
            self._start_response("500 Internal Server Error", [])
            self._write("Internal Server Error")
            self._done()
            tb = r"".join(traceback.format_exception(*sys.exc_info()))
            # We need a native-string newline to poke in the log
            # message, because we won't get a newline when using an
            # r-string. This is the easy way out.
            newline = chr(10)
            self.log_error(r"Exception happened during processing "
                           r"request '%s':%s%s", self.path, newline, tb)

    def do_PUT(self):
        self.do_POST()

    def do_GET(self):
        self.do_POST()

    def do_hgweb(self):
        self.sent_headers = False
        path, query = _splitURI(self.path)

        env = {}
        env[r'GATEWAY_INTERFACE'] = r'CGI/1.1'
        env[r'REQUEST_METHOD'] = self.command
        env[r'SERVER_NAME'] = self.server.server_name
        env[r'SERVER_PORT'] = str(self.server.server_port)
        env[r'REQUEST_URI'] = self.path
        env[r'SCRIPT_NAME'] = pycompat.sysstr(self.server.prefix)
        env[r'PATH_INFO'] = pycompat.sysstr(path[len(self.server.prefix):])
        env[r'REMOTE_HOST'] = self.client_address[0]
        env[r'REMOTE_ADDR'] = self.client_address[0]
        env[r'QUERY_STRING'] = query or r''

        if pycompat.ispy3:
            if self.headers.get_content_type() is None:
                env[r'CONTENT_TYPE'] = self.headers.get_default_type()
            else:
                env[r'CONTENT_TYPE'] = self.headers.get_content_type()
            length = self.headers.get('content-length')
        else:
            if self.headers.typeheader is None:
                env[r'CONTENT_TYPE'] = self.headers.type
            else:
                env[r'CONTENT_TYPE'] = self.headers.typeheader
            length = self.headers.getheader('content-length')
        if length:
            env[r'CONTENT_LENGTH'] = length
        for header in [h for h in self.headers.keys()
                       if h not in ('content-type', 'content-length')]:
            hkey = r'HTTP_' + header.replace(r'-', r'_').upper()
            hval = self.headers.get(header)
            hval = hval.replace(r'\n', r'').strip()
            if hval:
                env[hkey] = hval
        env[r'SERVER_PROTOCOL'] = self.request_version
        env[r'wsgi.version'] = (1, 0)
        env[r'wsgi.url_scheme'] = pycompat.sysstr(self.url_scheme)
        if env.get(r'HTTP_EXPECT', '').lower() == '100-continue':
            self.rfile = common.continuereader(self.rfile, self.wfile.write)

        env[r'wsgi.input'] = self.rfile
        env[r'wsgi.errors'] = _error_logger(self)
        env[r'wsgi.multithread'] = isinstance(self.server,
                                             socketserver.ThreadingMixIn)
        env[r'wsgi.multiprocess'] = isinstance(self.server,
                                              socketserver.ForkingMixIn)
        env[r'wsgi.run_once'] = 0

        wsgiref.validate.check_environ(env)

        self.saved_status = None
        self.saved_headers = []
        self.length = None
        self._chunked = None
        for chunk in self.server.application(env, self._start_response):
            self._write(chunk)
        if not self.sent_headers:
            self.send_headers()
        self._done()

    def send_headers(self):
        if not self.saved_status:
            raise AssertionError("Sending headers before "
                                 "start_response() called")
        saved_status = self.saved_status.split(None, 1)
        saved_status[0] = int(saved_status[0])
        self.send_response(*saved_status)
        self.length = None
        self._chunked = False
        for h in self.saved_headers:
            self.send_header(*h)
            if h[0].lower() == 'content-length':
                self.length = int(h[1])
        if (self.length is None and
            saved_status[0] != common.HTTP_NOT_MODIFIED):
            self._chunked = (not self.close_connection and
                             self.request_version == "HTTP/1.1")
            if self._chunked:
                self.send_header(r'Transfer-Encoding', r'chunked')
            else:
                self.send_header(r'Connection', r'close')
        self.end_headers()
        self.sent_headers = True

    def _start_response(self, http_status, headers, exc_info=None):
        code, msg = http_status.split(None, 1)
        code = int(code)
        self.saved_status = http_status
        bad_headers = ('connection', 'transfer-encoding')
        self.saved_headers = [h for h in headers
                              if h[0].lower() not in bad_headers]
        return self._write

    def _write(self, data):
        if not self.saved_status:
            raise AssertionError("data written before start_response() called")
        elif not self.sent_headers:
            self.send_headers()
        if self.length is not None:
            if len(data) > self.length:
                raise AssertionError("Content-length header sent, but more "
                                     "bytes than specified are being written.")
            self.length = self.length - len(data)
        elif self._chunked and data:
            data = '%x\r\n%s\r\n' % (len(data), data)
        self.wfile.write(data)
        self.wfile.flush()

    def _done(self):
        if self._chunked:
            self.wfile.write('0\r\n\r\n')
            self.wfile.flush()

    def version_string(self):
        if self.server.serverheader:
            return self.server.serverheader
        return httpservermod.basehttprequesthandler.version_string(self)

class _httprequesthandlerssl(_httprequesthandler):
    """HTTPS handler based on Python's ssl module"""

    url_scheme = 'https'

    @staticmethod
    def preparehttpserver(httpserver, ui):
        try:
            from .. import sslutil
            sslutil.modernssl
        except ImportError:
            raise error.Abort(_("SSL support is unavailable"))

        certfile = ui.config('web', 'certificate')

        # These config options are currently only meant for testing. Use
        # at your own risk.
        cafile = ui.config('devel', 'servercafile')
        reqcert = ui.configbool('devel', 'serverrequirecert')

        httpserver.socket = sslutil.wrapserversocket(httpserver.socket,
                                                     ui,
                                                     certfile=certfile,
                                                     cafile=cafile,
                                                     requireclientcert=reqcert)

    def setup(self):
        self.connection = self.request
        self.rfile = self.request.makefile(r"rb", self.rbufsize)
        self.wfile = self.request.makefile(r"wb", self.wbufsize)

try:
    import threading
    threading.activeCount() # silence pyflakes and bypass demandimport
    _mixin = socketserver.ThreadingMixIn
except ImportError:
    if util.safehasattr(os, "fork"):
        _mixin = socketserver.ForkingMixIn
    else:
        class _mixin(object):
            pass

def openlog(opt, default):
    if opt and opt != '-':
        return open(opt, 'ab')
    return default

class MercurialHTTPServer(_mixin, httpservermod.httpserver, object):

    # SO_REUSEADDR has broken semantics on windows
    if pycompat.iswindows:
        allow_reuse_address = 0

    def __init__(self, ui, app, addr, handler, **kwargs):
        httpservermod.httpserver.__init__(self, addr, handler, **kwargs)
        self.daemon_threads = True
        self.application = app

        handler.preparehttpserver(self, ui)

        prefix = ui.config('web', 'prefix')
        if prefix:
            prefix = '/' + prefix.strip('/')
        self.prefix = prefix

        alog = openlog(ui.config('web', 'accesslog'), ui.fout)
        elog = openlog(ui.config('web', 'errorlog'), ui.ferr)
        self.accesslog = alog
        self.errorlog = elog

        self.addr, self.port = self.socket.getsockname()[0:2]
        self.fqaddr = socket.getfqdn(addr[0])

        self.serverheader = ui.config('web', 'server-header')

class IPv6HTTPServer(MercurialHTTPServer):
    address_family = getattr(socket, 'AF_INET6', None)
    def __init__(self, *args, **kwargs):
        if self.address_family is None:
            raise error.RepoError(_('IPv6 is not available on this system'))
        super(IPv6HTTPServer, self).__init__(*args, **kwargs)

def create_server(ui, app):

    if ui.config('web', 'certificate'):
        handler = _httprequesthandlerssl
    else:
        handler = _httprequesthandler

    if ui.configbool('web', 'ipv6'):
        cls = IPv6HTTPServer
    else:
        cls = MercurialHTTPServer

    # ugly hack due to python issue5853 (for threaded use)
    try:
        import mimetypes
        mimetypes.init()
    except UnicodeDecodeError:
        # Python 2.x's mimetypes module attempts to decode strings
        # from Windows' ANSI APIs as ascii (fail), then re-encode them
        # as ascii (clown fail), because the default Python Unicode
        # codec is hardcoded as ascii.

        sys.argv # unwrap demand-loader so that reload() works
        reload(sys) # resurrect sys.setdefaultencoding()
        oldenc = sys.getdefaultencoding()
        sys.setdefaultencoding("latin1") # or any full 8-bit encoding
        mimetypes.init()
        sys.setdefaultencoding(oldenc)

    address = ui.config('web', 'address')
    port = util.getport(ui.config('web', 'port'))
    try:
        return cls(ui, app, (address, port), handler)
    except socket.error as inst:
        raise error.Abort(_("cannot start server at '%s:%d': %s")
                          % (address, port, encoding.strtolocal(inst.args[1])))