#!/usr/bin/env python

# $Id$
#
# Copyright (C) 2013  Internet Systems Consortium ("ISC")
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.

import os
import sys
import socket
import urllib2
import argparse
import platform
import textwrap
import subprocess
import rpki.autoconf

fqdn = socket.getfqdn()

vhost_template = """\

#
# Stuff that should be visible with both HTTP and HTTPS is (now)
# outside the vhost block (see if this works properly...).
#

#
# Allow access to the directory where rcynic-html writes
# its output files.
#
<Directory              %(RCYNIC_HTML_DIR)s>
%(allow)s
</Directory>

#
# Add alias pointing to rcynic-html's output files.
#
# If for some reason you need to change this, be careful to leave
# the trailing slash off the URL, otherwise /rcynic will be
# swallowed by the WSGIScriptAlias
#
Alias   /rcynic         %(RCYNIC_HTML_DIR)s/

#
# Allow access to the directory where pubd writes RRDP files.
#
<Directory              %(datarootdir)s/rpki/rrdp-publication/>
%(allow)s
</Directory>

#
# Add alias pointing to pubd's RRD output files.
#
Alias   /rrdp           %(datarootdir)s/rpki/rrdp-publication/

#
# RRDP "notification" file needs a short expiration: this is
# a critical part of how RRDP interacts with HTTP caching.
# Timeout is per current RRDP I-D, this will need to track
# any changes as the specification evolves.
#
<LocationMatch          ^/rrdp/notify[.]xml$>
  ExpiresActive         on
  ExpiresDefault        "access plus 1 minute"
</LocationMatch>

#
# By default, this configuration assumes that you use name-based
# virtual hosting.  If that's not what you want, you may need
# to change this.
#
<VirtualHost *:443>

  #
  # By default, we enable an HTTPS virtual host on this machine's
  # fully qualified domain name.  This works for simple
  # configurations, but if you're running a more complex Apache
  # configuration or want to run the GUI on a different hostname,
  # you may need to change this.
  #
  ServerName          %(fqdn)s

  #
  # Configure the WSGI application to run as a separate process from
  # the Apache daemon itself.
  #
  %(WSGI_DAEMON_PROCESS)s
  %(WSGI_PROCESS_GROUP)s

  #
  # Allow access to our WSGI directory.
  #
  <Directory %(datarootdir)s/rpki/wsgi>
%(allow)s
  </Directory>

  #
  # Define the URL to the RPKI GUI
  #
  WSGIScriptAlias /       %(datarootdir)s/rpki/wsgi/rpki.wsgi

  #
  # Allow access to static content (icons, etc).
  #
  <Directory %(datarootdir)s/rpki/media>
%(allow)s
  </Directory>

  #
  # Add the aliases Django expects for static content.
  #
  Alias   /media/         %(datarootdir)s/rpki/media/
  Alias   /site_media/    %(datarootdir)s/rpki/media/

  #
  # Redirect to the GUI dashboard when someone hits the bare vhost.
  #
  RedirectMatch   ^/$     /rpki/

  #
  # Enable HTTPS
  #
  SSLEngine               on

  #
  # Specify HTTPS server certificate and key files for this virtual host.
  # This should suffice for simple configurations, but if you're running
  # a more complex Apache configuration you may need to change or remove
  # these lines.
  #
  SSLCertificateFile     %(sysconfdir)s/rpki/apache.cer
  SSLCertificateKeyFile  %(sysconfdir)s/rpki/apache.key

  #
  # Recommended settings based on
  # https://wiki.mozilla.org/Security/Server_Side_TLS
  # (Currently using the Intermediate cipher suite)
  #
  SSLProtocol             all -SSLv2 -SSLv3
  SSLCipherSuite          ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA
  SSLHonorCipherOrder     on
  SSLCompression          off

  # OCSP Stapling, only in httpd 2.3.3 and later
  #SSLUseStapling          on
  #SSLStaplingResponderTimeout 5
  #SSLStaplingReturnResponderErrors off
  # On Apache 2.4+, SSLStaplingCache must be set *outside* of the VirtualHost
  #SSLStaplingCache        shmcb:/var/run/ocsp(128000)

  # Enable this if your want HSTS (recommended)
  # Header add Strict-Transport-Security "max-age=15768000"

  #
  # Take pity on users running Internet Exploder
  #
  BrowserMatch "MSIE [2-6]"  ssl-unclean-shutdown nokeepalive downgrade-1.0 force-response-1.0
  BrowserMatch "MSIE [17-9]" ssl-unclean-shutdown

</VirtualHost>
"""

allow_22_template = '''
    Order deny,allow
    Allow from all\
'''

allow_24_template = '''
    Require all granted\
'''

name_virtual_host_template = '''\
#
# In most cases we want to use name-based virtual hosting.  If this causes
# problems with your existing Apache configuration, try commenting out this line.
#
NameVirtualHost *:443

'''

def Guess(args):
    """
    Guess what platform this is and dispatch to platform constructor.
    """

    system = platform.system()
    if system == "FreeBSD":
        return FreeBSD(args)
    if system == "Darwin":
        return Darwin(args)
    if system == "Linux":
        distro = platform.linux_distribution()[0].lower()
        if distro == "debian":
            return Debian(args)
        if distro == "ubuntu":
            return Ubuntu(args)
        if distro in ("fedora", "centos"):
            return Redhat(args)
    raise NotImplementedError("Can't guess what platform this is, sorry")


class Platform(object):
    """
    Abstract base class representing an operating system platform.
    """

    apache_cer  = os.path.join(rpki.autoconf.sysconfdir, "rpki", "apache.cer")
    apache_key  = os.path.join(rpki.autoconf.sysconfdir, "rpki", "apache.key")

    apache_conf = os.path.join(rpki.autoconf.sysconfdir, "rpki", "apache.conf")
    apache_conf_sample = apache_conf + ".sample"

    apache_conf_preface = ""

    def __init__(self, args):
        self.args = args
        self.log("RPKI Apache configuration: platform \"%s\", action \"%s\"" % (
            self.__class__.__name__, args.action))
        getattr(self, args.action)()

    def log(self, msg):
        if self.args.verbose:
            print msg

    def run(self, *cmd, **kwargs):
        self.log("Running %s" % " ".join(cmd))
        subprocess.check_call(cmd, **kwargs)

    req_cmd  = ("openssl", "req", "-new",
                "-config", "/dev/stdin",
                "-out", "/dev/stdout",
                "-keyout", apache_key,
                "-newkey", "rsa:2048")

    x509_cmd = ("openssl", "x509", "-req", "-sha256",
                "-signkey", apache_key,
                "-in", "/dev/stdin",
                "-out", apache_cer,
                "-days", "3650")

    req_conf = '''\
          [req]
          default_bits            = 2048
          default_md              = sha256
          distinguished_name      = req_dn
          prompt                  = no
          encrypt_key             = no
          [req_dn]
          CN                      = %s
          ''' % fqdn

    def unlink(self, fn, silent = False):
        if os.path.lexists(fn):
            if  not silent:
                self.log("Removing %s" % fn)
            os.unlink(fn)
        elif  not silent:
            self.log("Would have removed %s if it existed" % fn)

    def del_certs(self, silent = False):
        self.unlink(self.apache_cer, silent)
        self.unlink(self.apache_key, silent)

    def add_certs(self):
        if os.path.exists(self.apache_cer) and os.path.exists(self.apache_key):
            return
        self.del_certs()
        req  = subprocess.Popen(self.req_cmd,
                                stdin = subprocess.PIPE,
                                stdout = subprocess.PIPE,
                                stderr = open("/dev/null", "w"))
        x509 = subprocess.Popen(self.x509_cmd,
                                stdin = req.stdout,
                                stderr = open("/dev/null", "w"))
        req.stdin.write(self.req_conf)
        req.stdin.close()
        if req.wait():
            raise subprocess.CalledProcessError(req.returncode,  self.req_cmd)
        if x509.wait():
            raise subprocess.CalledProcessError(x509.returncode, self.x509_cmd)
        self.log("Created %s and %s, chmoding %s" % (
            self.apache_cer, self.apache_key, self.apache_key))
        os.chmod(self.apache_key, 0600)

    _vhost = None

    @property
    def vhost(self):
        if self._vhost is None:
            allow = allow_22_template if self.args.apache_version <= 22 else allow_24_template
            self._vhost = vhost_template % dict(rpki.autoconf.__dict__, fqdn = fqdn, allow = allow)
        return self._vhost

    @property
    def name_virtual_host(self):
        return name_virtual_host_template if self.args.apache_version <= 22 else ""

    @property
    def too_complex(self):
        return textwrap.dedent('''\
          # It looks like you already have HTTPS enabled in your
          # Apache configuration, which makes your configuration too
          # complex for us to enable support for the RPKI GUI automatically.
          #
          # To enable support, take a look at %s
          # and copy what you need from that file into %s,
          # paying attention to the comments which mark the bits that
          # you might (or might not) need to change or omit, depending
          # on the details of your particular Apache configuration.
          ''' % (self.apache_conf_sample, self.apache_conf))

    @property
    def apache_conf_target(self):
        raise NotImplementedError

    def restart(self):
        raise NotImplementedError

    def install(self):
        with open(self.apache_conf_sample, "w") as f:
            self.log("Writing %s" % f.name)
            f.write(self.apache_conf_preface)
            f.write(self.name_virtual_host)
            f.write(self.vhost)
        if not os.path.exists(self.apache_conf):
            self.unlink(self.apache_conf)
            with open(self.apache_conf, "w") as f:
                self.log("Writing %s" % f.name)
                if self.test_url("https://%s/" % fqdn):
                    f.write(self.too_complex)
                    sys.stdout.write(self.too_complex)
                else:
                    if not self.test_tcp("localhost", 443):
                        f.write(self.apache_conf_preface)
                        f.write(self.name_virtual_host)
                    f.write(self.vhost)
        if not os.path.exists(self.apache_conf_target):
            self.unlink(self.apache_conf_target)
            self.log("Symlinking %s to %s" % (
                self.apache_conf_target, self.apache_conf))
            os.symlink(self.apache_conf, self.apache_conf_target)
        self.add_certs()
        self.enable()
        self.restart()

    def enable(self):
        pass

    def disable(self):
        pass

    def remove(self):
        try:
            same = open(self.apache_conf, "r").read() == open(self.apache_conf_sample, "r").read()
        except:
            same = False
        self.unlink(self.apache_conf_sample)
        if same:
            self.unlink(self.apache_conf)
        self.unlink(self.apache_conf_target)
        self.disable()
        self.restart()

    def purge(self):
        self.remove()
        self.unlink(self.apache_conf)
        self.del_certs()

    @staticmethod
    def test_url(url = "https://localhost/"):
        try:
            urllib2.urlopen(url).close()
        except IOError:
            return False
        else:
            return True

    @staticmethod
    def test_tcp(host = "localhost", port = 443, family = socket.AF_UNSPEC, proto = socket.SOCK_STREAM):
        try:
            addrinfo = socket.getaddrinfo(host, port, family, proto)
        except socket.error:
            return False
        for af, socktype, proto, canon, sa in addrinfo: # pylint: disable=W0612
            try:
                s = socket.socket(af, socktype, proto)
                s.connect(sa)
                s.close()
            except socket.error:
                continue
            else:
                return True
        return False


class FreeBSD(Platform):
    """
    FreeBSD.
    """

    # On FreeBSD we have to ask httpd what version it is before we know
    # where to put files or what to call the service.  In FreeBSD's makefiles,
    # this value is called APACHE_VERSION, and is calculated thusly:
    #
    # httpd -V | sed  -ne 's/^Server version: Apache\/\([0-9]\)\.\([0-9]*\).*/\1\2/p'

    _apache_name = None

    @property
    def apache_name(self):
        if self._apache_name is None:
            self._apache_name = "apache%s" % self.args.apache_version
        return self._apache_name

    @property
    def apache_conf_target(self):
        return "/usr/local/etc/%s/Includes/rpki.conf" % self.apache_name

    apache_conf_preface = textwrap.dedent('''\
      # These directives tell Apache to listen on the HTTPS port
      # and to enable name-based virtual hosting.  If you already
      # have HTTPS enabled elsewhere in your configuration, you may
      # need to remove these.

      Listen [::]:443
      Listen 0.0.0.0:443
      ''')

    def restart(self):
        self.run("service", self.apache_name, "restart")


class Debian(Platform):
    """
    Debian and related platforms like Ubuntu.
    """

    # Pull the current version number for released code.  Use
    # something very large when there is no version (eg, "sid").
    @property
    def distribution_version(self):
        v = platform.linux_distribution()[1].split(".")
        if all(d.isdigit() for d in v):
            return tuple(int(d) for d in v)
        else:
            return (99999999, 0)

    # On Debian, the filename must end in .conf on Stretch and must not
    # end in .conf on Wheezy.  Haven't checked Jessie yet, will need to
    # update this if we ever sort out the version skew mess on Jessie.
    @property
    def apache_conf_target(self):
        if self.distribution_version < (8, 0):
            return "/etc/apache2/sites-available/rpki"
        else:
            return "/etc/apache2/sites-available/rpki.conf"

    snake_oil_cer = "/etc/ssl/certs/ssl-cert-snakeoil.pem"
    snake_oil_key = "/etc/ssl/private/ssl-cert-snakeoil.key"

    def add_certs(self):
        if not os.path.exists(self.snake_oil_cer) or not os.path.exists(self.snake_oil_key):
            return Platform.add_certs(self)
        if not os.path.exists(self.apache_cer):
            self.unlink(self.apache_cer)
            os.symlink(self.snake_oil_cer, self.apache_cer)
        if not os.path.exists(self.apache_key):
            self.unlink(self.apache_key)
            os.symlink(self.snake_oil_key, self.apache_key)

    def enable(self):
        self.run("a2enmod", "ssl")
        self.run("a2enmod", "expires")
        self.run("a2ensite", "rpki")
        #
        # In light of BREACH and CRIME attacks, mod_deflate is looking
        # like a bad idea, so make sure it's off.
        self.run("a2dismod", "-f", "deflate")

    def disable(self):
        self.run("a2dissite", "rpki")

    def restart(self):
        self.run("service", "apache2", "restart")


class Ubuntu(Debian):

    # On Ubuntu, the filename must end in .conf on Trusty and must not
    # end in .conf on Precise.
    @property
    def apache_conf_target(self):
        if self.distribution_version < (14, 0):
            return "/etc/apache2/sites-available/rpki"
        else:
            return "/etc/apache2/sites-available/rpki.conf"


class NIY(Platform):                    # pylint: disable=W0223
    def __init__(self, args):
        super(NIY, self).__init__(args)
        raise NotImplementedError("Platform %s not implemented yet, sorry" % self.__class__.__name__)

class Redhat(NIY):                      # pylint: disable=W0223
    "Redhat family of Linux distributions (Fedora, CentOS)."

class Darwin(NIY):                      # pylint: disable=W0223
    "Mac OS X (aka Darwin)."


def main():
    """
    Generate and (de)install configuration suitable for using Apache httpd
    to drive the RPKI web interface under WSGI.
    """

    parser = argparse.ArgumentParser(description = __doc__)
    group1 = parser.add_mutually_exclusive_group()
    group2 = parser.add_mutually_exclusive_group()

    parser.add_argument("-v", "--verbose",
                        help = "whistle while you work", action = "store_true")
    parser.add_argument("--apache-version",
                        help = "Apache version (default " + rpki.autoconf.APACHE_VERSION + ")",
                        type = int,             default =  rpki.autoconf.APACHE_VERSION)

    group1.add_argument("--freebsd",
                        help = "configure for FreeBSD",
                        action = "store_const", dest = "platform", const = FreeBSD)
    group1.add_argument("--debian",
                        help = "configure for Debian",
                        action = "store_const", dest = "platform", const = Debian)
    group1.add_argument("--ubuntu",
                        help = "configure for Ubuntu",
                        action = "store_const", dest = "platform", const = Ubuntu)
    group1.add_argument("--redhat", "--fedora", "--centos",
                        help = "configure for Redhat/Fedora/CentOS",
                        action = "store_const", dest = "platform", const = Redhat)
    group1.add_argument("--macosx", "--darwin",
                        help = "configure for Mac OS X (Darwin)",
                        action = "store_const", dest = "platform", const = Darwin)
    group1.add_argument("--guess",
                        help = "guess which platform configuration to use",
                        action = "store_const", dest = "platform", const = Guess)

    group2.add_argument("-i", "--install",
                        help = "install configuration",
                        action = "store_const", dest = "action", const = "install")
    group2.add_argument("-r", "--remove", "--deinstall", "--uninstall",
                        help = "remove configuration",
                        action = "store_const", dest = "action", const = "remove")
    group2.add_argument("-P", "--purge",
                        help = "remove configuration with extreme prejudice",
                        action = "store_const", dest = "action", const = "purge")

    parser.set_defaults(platform = Guess, action = "install")
    args = parser.parse_args()

    try:
        args.platform(args)
    except Exception, e:
        sys.exit(str(e))

if __name__ == "__main__":
    main()