#!/usr/bin/python -tt

# -*- coding: utf-8 -*-

#

# This script will help you with migration squid-3.3 conf files to squid-3.5 conf files

# Copyright (C) 2016 Red Hat, Inc.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# he Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License along

# with this program; if not, write to the Free Software Foundation, Inc.,

# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

#

# Authors: Lubos Uhliarik <luhliari@redhat.com>

import sys

import os

import re

import shutil

import traceback

import argparse

import glob

class ConfMigration:

    RE_LOG_ACCESS="log_access\s+(\w+)\s+"

    RE_LOG_ACCESS_DENY_REP="access_log none "

    RE_LOG_ACCESS_ALLOW_REP="access_log daemon:/var/log/squid/access.log squid "

    RE_LOG_ACCESS_TEXT="log_access"

    RE_LOG_ICAP="log_icap\s+"

    RE_LOG_ICAP_REP="icap_log daemon:/var/log/squid/icap.log "

    RE_LOG_ICAP_TEXT="log_icap"

    RE_HIER_STOPLIST="hierarchy_stoplist\s+(.*)"

    RE_HIER_STOPLIST_REP="acl %s url_regex %s\nalways_direct allow %s"

    RE_HIER_STOPLIST_TEXT="hierarchy_stoplist"

    HIER_ACL_NAME="migrated_hs_%d_%d"

    RE_INCLUDE_CHECK="\s*include\s+(.*)"

    COMMENT_FMT="# migrated automatically by squid-migrate-conf, the original configuration was: %s\n%s"

    DEFAULT_SQUID_CONF="/etc/squid/squid.conf"

    DEFAULT_BACKUP_EXT=".bak"

    DEFAULT_LEVEL_INDENT=3

    MAX_NESTED_INCLUDES=16

    def __init__(self, args, level=0, squid_conf='', conf_seq=0):

        self.args = args

        if squid_conf:

            self.squid_conf = squid_conf

        else:

            self.squid_conf = args.squid_conf

        self.write_changes = args.write_changes

        self.debug = args.debug

        self.conf_seq = conf_seq

        self.acl_seq = 0

        self.line_num = 0

        self.level = level

        if (not os.path.isfile(self.squid_conf)):

            sys.stderr.write("%sError: the config file %s does not exist\n" % (self.get_prefix_str(), self.squid_conf))

            sys.exit(1)

        self.squid_bak_conf = self.get_backup_name()

        self.migrated_squid_conf_data = []

        self.squid_conf_data = None

        print ("Migrating: " + self.squid_conf)

    def print_info(self, text=''):

        if (self.debug):

            print "%s%s" % (self.get_prefix_str(), text)

    def get_backup_name(self):

        file_idx = 1

        tmp_fn = self.squid_conf + self.DEFAULT_BACKUP_EXT

        while (os.path.isfile(tmp_fn)):

            tmp_fn = self.squid_conf + self.DEFAULT_BACKUP_EXT + str(file_idx)

            file_idx = file_idx + 1

        return tmp_fn

    #

    #  From squid config documentation:

    #

    #  Configuration options can be included using the "include" directive.

    #  Include takes a list of files to include. Quoting and wildcards are

    #  supported.

    #

    #  For example,

    #

    #  include /path/to/included/file/squid.acl.config

    #

    #  Includes can be nested up to a hard-coded depth of 16 levels.

    #  This arbitrary restriction is to prevent recursive include references

    #  from causing Squid entering an infinite loop whilst trying to load

    #  configuration files.

    #

    def check_include(self, line=''):

        m = re.match(self.RE_INCLUDE_CHECK, line)

        include_list = ""

        if not (m is None):

             include_list = re.split('\s+', m.group(1))

             for include_file_re in include_list:

                 # included file can be written in regexp syntax

                 for include_file in glob.glob(include_file_re):

                     self.print_info("A config file %s was found and it will be included" % (include_file))

                     if os.path.isfile(include_file):

                         self.print_info("Migrating the included config file %s" % (include_file))

                         conf = ConfMigration(self.args, self.level+1, include_file, self.conf_seq+1)

                         conf.migrate()

                 # check, if included file exists

                 if (len(glob.glob(include_file_re)) == 0 and not (os.path.isfile(include_file_re))):

                     self.print_info("The config file %s does not exist." % (include_file_re))

    def print_sub_text(self, text, new_str):

        if self.write_changes:

            print "File: '%s', line: %d - the directive %s was replaced by %s" % (self.squid_conf, self.line_num, text, new_str)

        else:

            print "File: '%s', line: %d - the directive %s could be replaced by %s" % (self.squid_conf, self.line_num, text, new_str)

    def add_conf_comment(self, old_line, line):

        return self.COMMENT_FMT % (old_line, line)

    def sub_line_ad(self, line, line_re, allow_sub, deny_sub, text):

        new_line = line

        m = re.match(line_re, line)

        if not (m is None):

            # check, if allow or deny was used and select coresponding sub

            sub_text = allow_sub

            if (re.match('allow', m.group(1), re.IGNORECASE)):

                new_line = re.sub(line_re, sub_text, line)

            elif (re.match('deny', m.group(1), re.IGNORECASE)):

                sub_text = deny_sub

                new_line = re.sub(line_re, sub_text, line)

            # print out, if there was any change and add comment to conf line, if so

            if not (new_line is line):

                self.print_sub_text(text + " " +  m.group(1), sub_text)

                new_line = self.add_conf_comment(line, new_line)

        return new_line

    def sub_line(self, line, line_re, sub, text):

        new_line = line

        m = re.match(line_re, line)

        if not (m is None):

            new_line = re.sub(line_re, sub, line)

            # print out, if there was any change and add comment to conf line, if so

            if not (new_line is line):

                self.print_sub_text(text, sub)

                new_line = self.add_conf_comment(line, new_line)

        return new_line

    def rep_hier_stoplist(self, line, sub, words):

        wordlist = words.split(' ')

        esc_wordlist = []

        for w in wordlist:

            esc_wordlist.append(re.escape(w))

        # unique acl name for hierarchy_stoplist acl

        acl_name = self.HIER_ACL_NAME % (self.conf_seq, self.acl_seq)

        return sub % (acl_name, ' '.join(esc_wordlist), acl_name)

    def sub_hier_stoplist(self, line, line_re, sub, text):

        new_line = line

        m = re.match(line_re, line)

        if (not (m is None)):

            new_line = self.rep_hier_stoplist(line, sub, m.group(1))

        # print out, if there was any change and add comment to conf line, if so

        if not (new_line is line):

            self.print_sub_text(text, sub)

            new_line = self.add_conf_comment(line, new_line)

        return new_line

    def process_conf_lines(self):

        for line in self.squid_conf_data.split(os.linesep):

            # do not migrate comments

            if not line.strip().startswith('#'):

               self.check_include(line)

               line = self.sub_line_ad(line, self.RE_LOG_ACCESS, self.RE_LOG_ACCESS_ALLOW_REP, self.RE_LOG_ACCESS_DENY_REP, self.RE_LOG_ACCESS_TEXT)

               line = self.sub_line(line, self.RE_LOG_ICAP, self.RE_LOG_ICAP_REP, self.RE_LOG_ICAP_TEXT)

               line = self.sub_hier_stoplist(line, self.RE_HIER_STOPLIST, self.RE_HIER_STOPLIST_REP, self.RE_HIER_STOPLIST_TEXT)

            self.migrated_squid_conf_data.append(line)

            self.line_num = self.line_num + 1

    def migrate(self):

        # prevent infinite loop

        if (self.level > ConfMigration.MAX_NESTED_INCLUDES):

            sys.stderr.write("WARNING: the maximum number of nested includes was reached\n")

            return

        self.read_conf()

        self.process_conf_lines()

        if self.write_changes:

            if (not (set(self.migrated_squid_conf_data) == set(self.squid_conf_data.split(os.linesep)))):

                self.write_conf()

        self.print_info("The migration finished successfully")

    def get_prefix_str(self):

        return (("    " * int(self.level)) + "["+  self.squid_conf + "@%d]: " % (self.line_num))

    def read_conf(self):

        self.print_info("Reading squid conf: " + self.squid_conf)

        try:

           self.in_file = open(self.squid_conf, 'r')

           self.squid_conf_data = self.in_file.read()

           self.in_file.close()

        except Exception as e:

           sys.stderr.write("%sError: %s\n" % (self.get_prefix_str(), e))

           sys.exit(1)

    def write_conf(self):

        self.print_info("Creating backup conf: %s" % (self.squid_bak_conf))

        self.print_info("Writing changes to: %s" % (self.squid_conf))

        try:

           shutil.copyfile(self.squid_conf, self.squid_bak_conf)

           self.out_file = open(self.squid_conf, "w")

           self.out_file.write(os.linesep.join(self.migrated_squid_conf_data))

           self.out_file.close()

        except Exception as e:

           sys.stderr.write("%s Error: %s\n" % (self.get_prefix_str(), e))

           sys.exit(1)

def parse_args():

    parser = argparse.ArgumentParser(description='The script migrates the squid 3.3 configuration files to configuration files which are compatible with squid 3.5.')

    parser.add_argument('--conf', dest='squid_conf', action='store',

                        default=ConfMigration.DEFAULT_SQUID_CONF,

                        help='specify filename of squid configuration (default: %s)' % (ConfMigration.DEFAULT_SQUID_CONF))

    parser.add_argument('--write-changes', dest='write_changes', action='store_true',

                        default=False,

                        help='The changes are written to corresponding configuration files')

    parser.add_argument('--debug', dest="debug", action='store_true', default=False, help='print debug messages to stderr')

    return parser.parse_args()

if __name__ == '__main__':

    # parse args from command line

    args = parse_args()

    # check if config file exists

    if (not os.path.exists(args.squid_conf)):

        sys.stderr.write("Error: the file %s does not exist\n" % (args.squid_conf))

        sys.exit(1)

    # change working directory

    script_dir = os.getcwd()

    if (os.path.dirname(args.squid_conf)):

        os.chdir(os.path.dirname(args.squid_conf))

    # start migration

    try:

        conf = ConfMigration(args, 0)

        conf.migrate()

    finally:

        print ""

        if not args.write_changes:

            print "The changes have NOT been written to config files.\nUse the --write-changes option to write the changes"

        else:

            print "The changes have been written to config files!"

        os.chdir(script_dir)