#!/usr/bin/env python

#

# Copyright 2008 LShift Ltd

# Copyright 2005-2007 by Intevation GmbH <intevation@intevation.de>

# Author(s):

# Paul Crowley <paul@lshift.net>

# Thomas Arendsen Hein <thomas@intevation.de>

# with ideas from  Mathieu PASQUET <kiorky@cryptelium.net>

#

# This software may be used and distributed according to the terms

# of the GNU General Public License, incorporated herein by reference.

"""

hg-ssh - limit access to hg repositories reached via ssh.  Part of

hg-admin-tools.

This script is called by hg-ssh-wrapper with two arguments:

hg-ssh <rulefile> <keyname>

It expects to find the command the SSH user was trying to run in the

environment variable SSH_ORIGINAL_COMMAND, and uses it to determine

what the user was trying to do and to what repository, and then checks

each rule in the rule file in turn for a matching rule which decides

what to do, defaulting to disallowing the action.

"""

# enable importing on demand to reduce startup time

from mercurial import demandimport; demandimport.enable()

from mercurial import dispatch

import sys, os, re

def fail(message):

    #logfile.write("Fail: %s\n" % message)

    sys.stderr.write(message + "\n")

    sys.exit(-1)

# Note that this currently disallows dots in path components - if you change it

# to allow them ensure that "." and ".." are disallowed in path components.

allowedchars = "A-Za-z0-9_-"

goodpathre = re.compile("([%s]+/)*[%s]+$" % (allowedchars, allowedchars))

def goodpath(path):

    if goodpathre.match(path) is None:

        fail("Disallowing path: %s" % path)

# Don't put anything except *A-Za-z0-9_- in rule globs or

# you'll probably break security.  No regexp metachars, not even .

# We may fix this later.

goodglobre = re.compile("[*/%s]+$" % allowedchars)

def globmatch(pattern, match):

    if goodglobre.match(pattern) is None:

        fail("Bad glob pattern in auth config: %s" % pattern)

    pattern = pattern.replace(".", r'\.')

    pattern = pattern.replace("*", "[%s]*" % allowedchars)

    return re.compile(pattern + "$").match(match) is not None

def testrule(rulefile, keyname, path, applicable):

    goodpath(keyname)

    goodpath(path)

    f = open(rulefile)

    try:

        for l in f:

            l = l.strip()

            if l == "" or l.startswith("#"):

                continue

            rule, rk, rp = l.split()

            if globmatch(rk, keyname) and globmatch(rp, path):

                #logfile.write("Used rule: %s\n" % l)

                return rule in applicable

    finally:

        f.close()

def get_cmd(rulefile, keyname, cmd):

    if cmd.startswith('hg -R ') and cmd.endswith(' serve --stdio'):

        path = cmd[6:-14]

        if testrule(rulefile, keyname, path, set(["allow", "init"])):

            return ['-R', path, 'serve', '--stdio']

    elif cmd.startswith('hg init '):

        path = cmd[8:]

        if testrule(rulefile, keyname, path, set(["init"])):

            return ['init', path]

    fail("Illegal command %r" % cmd)

#logfile = open("/tmp/hg-ssh.%d.txt" % os.getpid(), "w")

#logfile.write("Started: %s\n" % sys.argv)

if len(sys.argv) != 3:

    fail("hg-ssh must have exactly two arguments (%s)" 

        % sys.argv)

rulefile = sys.argv[1]

keyname = sys.argv[2]

todispatch = get_cmd(rulefile, keyname, 

    os.environ.get('SSH_ORIGINAL_COMMAND', '?'))

dispatch.dispatch(todispatch)