view mercurial/hgweb/common.py @ 32983:0d757af1ea67

configitems: add a basic class to hold config item information

The goal of this class is allow explicit declaration for the available config
option. This class will hold the data for one specific config item.

To keep it simple we start centralizing the handling of the default config value.

In the future we can expect more data to be carried on this class. For example:
 - documentation,
 - status (experimental, advanced, normal, deprecated),
 - aliases,
 - expected type,
 - etc...

# 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