view mercurial/hgweb/common.py @ 33766:4c706037adef

wireproto: overhaul iterating batcher code (API)

The remote batching code is difficult to read. Let's improve it.

As part of the refactor, the future returned by method calls on
batchiter() instances is now populated. However, you still need to
consume the results() generator for the future to be set.  But at
least now we can stuff the future somewhere and not have to worry
about aligning method call order with result order since you can
use a future to hold the result.

Also as part of the change, we now verify that @batchable generators
yield exactly 2 values. In other words, we enforce their API.

The non-iter batcher has been unused since b6e71f8af5b8. And to my
surprise we had no explicit unit test coverage of it! test-batching.py
has been overhauled to use the iterating batcher.

Since the iterating batcher doesn't allow non-batchable method
calls nor local calls, tests have been updated to reflect reality.
The iterating batcher has been used for multiple releases apparently
without major issue. So this shouldn't cause alarm.

.. api::

   @peer.batchable functions must now yield exactly 2 values

Differential Revision: https://phab.mercurial-scm.org/D319

# hgweb/common.py - Utility functions needed by hgweb_mod and hgwebdir_mod
#
# Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
# Copyright 2005, 2006 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 base64
import errno
import mimetypes
import os
import uuid

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

httpserver = util.httpserver

HTTP_OK = 200
HTTP_NOT_MODIFIED = 304
HTTP_BAD_REQUEST = 400
HTTP_UNAUTHORIZED = 401
HTTP_FORBIDDEN = 403
HTTP_NOT_FOUND = 404
HTTP_METHOD_NOT_ALLOWED = 405
HTTP_SERVER_ERROR = 500


def ismember(ui, username, userlist):
    """Check if username is a member of userlist.

    If userlist has a single '*' member, all users are considered members.
    Can be overridden by extensions to provide more complex authorization
    schemes.
    """
    return userlist == ['*'] or username in userlist

def checkauthz(hgweb, req, op):
    '''Check permission for operation based on request data (including
    authentication info). Return if op allowed, else raise an ErrorResponse
    exception.'''

    user = req.env.get('REMOTE_USER')

    deny_read = hgweb.configlist('web', 'deny_read')
    if deny_read and (not user or ismember(hgweb.repo.ui, user, deny_read)):
        raise ErrorResponse(HTTP_UNAUTHORIZED, 'read not authorized')

    allow_read = hgweb.configlist('web', 'allow_read')
    if allow_read and (not ismember(hgweb.repo.ui, user, allow_read)):
        raise ErrorResponse(HTTP_UNAUTHORIZED, 'read not authorized')

    if op == 'pull' and not hgweb.allowpull:
        raise ErrorResponse(HTTP_UNAUTHORIZED, 'pull not authorized')
    elif op == 'pull' or op is None: # op is None for interface requests
        return

    # enforce that you can only push using POST requests
    if req.env['REQUEST_METHOD'] != 'POST':
        msg = 'push requires POST request'
        raise ErrorResponse(HTTP_METHOD_NOT_ALLOWED, msg)

    # require ssl by default for pushing, auth info cannot be sniffed
    # and replayed
    scheme = req.env.get('wsgi.url_scheme')
    if hgweb.configbool('web', 'push_ssl', True) and scheme != 'https':
        raise ErrorResponse(HTTP_FORBIDDEN, 'ssl required')

    deny = hgweb.configlist('web', 'deny_push')
    if deny and (not user or ismember(hgweb.repo.ui, user, deny)):
        raise ErrorResponse(HTTP_UNAUTHORIZED, 'push not authorized')

    allow = hgweb.configlist('web', 'allow_push')
    if not (allow and ismember(hgweb.repo.ui, user, allow)):
        raise ErrorResponse(HTTP_UNAUTHORIZED, 'push not authorized')

# Hooks for hgweb permission checks; extensions can add hooks here.
# Each hook is invoked like this: hook(hgweb, request, operation),
# where operation is either read, pull or push. Hooks should either
# raise an ErrorResponse exception, or just return.
#
# It is possible to do both authentication and authorization through
# this.
permhooks = [checkauthz]


class ErrorResponse(Exception):
    def __init__(self, code, message=None, headers=None):
        if message is None:
            message = _statusmessage(code)
        Exception.__init__(self, message)
        self.code = code
        if headers is None:
            headers = []
        self.headers = headers

class continuereader(object):
    def __init__(self, f, write):
        self.f = f
        self._write = write
        self.continued = False

    def read(self, amt=-1):
        if not self.continued:
            self.continued = True
            self._write('HTTP/1.1 100 Continue\r\n\r\n')
        return self.f.read(amt)

    def __getattr__(self, attr):
        if attr in ('close', 'readline', 'readlines', '__iter__'):
            return getattr(self.f, attr)
        raise AttributeError

def _statusmessage(code):
    responses = httpserver.basehttprequesthandler.responses
    return responses.get(code, ('Error', 'Unknown error'))[0]

def statusmessage(code, message=None):
    return '%d %s' % (code, message or _statusmessage(code))

def get_stat(spath, fn):
    """stat fn if it exists, spath otherwise"""
    cl_path = os.path.join(spath, fn)
    if os.path.exists(cl_path):
        return os.stat(cl_path)
    else:
        return os.stat(spath)

def get_mtime(spath):
    return get_stat(spath, "00changelog.i").st_mtime

def ispathsafe(path):
    """Determine if a path is safe to use for filesystem access."""
    parts = path.split('/')
    for part in parts:
        if (part in ('', os.curdir, os.pardir) or
            pycompat.ossep in part or
            pycompat.osaltsep is not None and pycompat.osaltsep in part):
            return False

    return True

def staticfile(directory, fname, req):
    """return a file inside directory with guessed Content-Type header

    fname always uses '/' as directory separator and isn't allowed to
    contain unusual path components.
    Content-Type is guessed using the mimetypes module.
    Return an empty string if fname is illegal or file not found.

    """
    if not ispathsafe(fname):
        return

    fpath = os.path.join(*fname.split('/'))
    if isinstance(directory, str):
        directory = [directory]
    for d in directory:
        path = os.path.join(d, fpath)
        if os.path.exists(path):
            break
    try:
        os.stat(path)
        ct = mimetypes.guess_type(path)[0] or "text/plain"
        with open(path, 'rb') as fh:
            data = fh.read()

        req.respond(HTTP_OK, ct, body=data)
    except TypeError:
        raise ErrorResponse(HTTP_SERVER_ERROR, 'illegal filename')
    except OSError as err:
        if err.errno == errno.ENOENT:
            raise ErrorResponse(HTTP_NOT_FOUND)
        else:
            raise ErrorResponse(HTTP_SERVER_ERROR, err.strerror)

def paritygen(stripecount, offset=0):
    """count parity of horizontal stripes for easier reading"""
    if stripecount and offset:
        # account for offset, e.g. due to building the list in reverse
        count = (stripecount + offset) % stripecount
        parity = (stripecount + offset) / stripecount & 1
    else:
        count = 0
        parity = 0
    while True:
        yield parity
        count += 1
        if stripecount and count >= stripecount:
            parity = 1 - parity
            count = 0

def get_contact(config):
    """Return repo contact information or empty string.

    web.contact is the primary source, but if that is not set, try
    ui.username or $EMAIL as a fallback to display something useful.
    """
    return (config("web", "contact") or
            config("ui", "username") or
            encoding.environ.get("EMAIL") or "")

def caching(web, req):
    tag = 'W/"%s"' % web.mtime
    if req.env.get('HTTP_IF_NONE_MATCH') == tag:
        raise ErrorResponse(HTTP_NOT_MODIFIED)
    req.headers.append(('ETag', tag))

def cspvalues(ui):
    """Obtain the Content-Security-Policy header and nonce value.

    Returns a 2-tuple of the CSP header value and the nonce value.

    First value is ``None`` if CSP isn't enabled. Second value is ``None``
    if CSP isn't enabled or if the CSP header doesn't need a nonce.
    """
    # Don't allow untrusted CSP setting since it be disable protections
    # from a trusted/global source.
    csp = ui.config('web', 'csp', untrusted=False)
    nonce = None

    if csp and '%nonce%' in csp:
        nonce = base64.urlsafe_b64encode(uuid.uuid4().bytes).rstrip('=')
        csp = csp.replace('%nonce%', nonce)

    return csp, nonce