#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import sys
import re
import socket
import getopt
import threading
import subprocess
import shlex
import time
import select

blackhole = (
    '10::2222',
    '101::1234',
    '2001::212',
    '2001:da8:112::21ae',
    '2003:ff:1:2:3:4:5fff:6',
    '2003:ff:1:2:3:4:5fff:7',
    '2003:ff:1:2:3:4:5fff:8',
    '2003:ff:1:2:3:4:5fff:9',
    '2003:ff:1:2:3:4:5fff:10',
    '2003:ff:1:2:3:4:5fff:11',
    '2003:ff:1:2:3:4:5fff:12',
    '21:2::2',
    '2123::3e12',
    '1.2.3.4',
    '127.0.0.1',
    '159.106.121.75',
    '202.181.7.85',
    '203.98.7.65',
    '243.185.187.39',
    '37.61.54.158',
    '4.36.66.178',
    '46.82.174.68',
    '59.24.3.173',
    '64.33.88.161',
    '78.16.49.15',
    '8.7.198.45',
    '93.46.8.89',
)

dns = {
    'google_a': '2001:4860:4860::8888',
    'google_b': '2001:4860:4860::8844',
    'he_net': '2001:470:20::2',
    'lax_he_net': '2001:470:0:9d::2'
}

config = {
    'dns': dns['google_b'],
    'infile': '',
    'outfile': '',
    'querytype': 'aaaa',
    'cname': False,
    'threadnum': 10
}

hosts = []
done_num = 0
thread_lock = threading.Lock()
running = True

class worker_thread(threading.Thread):
    def __init__(self, start_pt, end_pt):
        threading.Thread.__init__(self)
        self.start_pt = start_pt
        self.end_pt = end_pt

    def run(self):
        global hosts, done_num
        for i in range(self.start_pt, self.end_pt):
            if not running: break

            line = hosts[i].strip()

            if line == '' or line[0:2] == '##':
                hosts[i] = line + '\r\n'
                with thread_lock: done_num += 1
                continue

            # uncomment line
            line = line.lstrip('#')
            # split comment that appended to line
            comment = ''
            p = line.find('#')
            if p > 0:
                comment = line[p:]
                line = line[:p]
            arr = line.split()

            if len(arr) == 1:
                domain = arr[0]
            else:
                domain = arr[1]

            flag = False
            if validate_domain(domain):
                cname, ip = query_domain(domain, False)

                if ip == '' or ip in blackhole:
                    cname, ip = query_domain(domain, True)

                if ip:
                    flag = True
                    arr[0] = ip
                    if len(arr) == 1:
                        arr.append(domain)
                    if config['cname'] and cname:
                        arr.append('#' + cname)
                    else:
                        if comment:
                            arr.append(comment)

            if not flag:
                arr[0] = '#' + arr[0]
                if comment:
                    arr.append(comment)

            hosts[i] = ' '.join(arr)
            hosts[i] += '\r\n'
            with thread_lock: done_num += 1

class watcher_thread(threading.Thread):
    def run(self):
        total_num = len(hosts)

        wn = int(config['threadnum'])
        if wn > total_num:
            wn = total_num
        print "There are %d threads working..." % wn
        print "Press 'Enter' to exit.\n"

        while True:
            if sys.stdin in select.select([sys.stdin], [], [], 0)[0]:
                raw_input()
                print 'Waiting threads to exit...'
                global running
                with thread_lock:
                    running = False
                break

            dn = done_num
            outbuf = "Total: %d lines, Done: %d lines, Ratio: %d %%.\r"\
                     % (total_num, dn, dn * 100 / total_num)
            print outbuf,
            sys.stdout.flush()

            if dn == total_num:
                print outbuf
                break

            time.sleep(1)

def query_domain(domain, tcp):
    cmd = "dig +short +time=2 -6 %s @'%s' '%s'"\
        % (config['querytype'], config['dns'], domain)

    if tcp:
        cmd = cmd + ' +tcp'

    proc = subprocess.Popen(shlex.split(cmd), stdout=subprocess.PIPE)
    out, _ = proc.communicate()
    outarr = out.splitlines()

    cname = ip = ''
    for v in outarr:
        if cname == '' and validate_domain(v[:-1]):
            cname = v[:-1]
        if ip == '' and validate_ip_addr(v):
            ip = v
            break

    return (cname, ip)

def validate_domain(domain):
    pattern = '^((?!-)[*A-Za-z0-9-]{1,63}(?<!-)\\.)+[A-Za-z]{2,6}$'
    p = re.compile(pattern)
    m = p.match(domain)
    if m:
        return True
    else:
        return False

def validate_ip_addr(ip_addr):
    if ':' in ip_addr:
        try:
            socket.inet_pton(socket.AF_INET6, ip_addr)
            return True
        except socket.error:
            return False
    else:
        try:
            socket.inet_pton(socket.AF_INET, ip_addr)
            return True
        except socket.error:
            return False

def print_help():
    print '''usage: update_hosts [OPTIONS] FILE
A simple multi-threading tool used to update hosts file.

Options:
  -h, --help             show this help message and exit
  -s DNS                 set another dns server, default: 2001:4860:4860::8844
  -o OUT_FILE            ouput file, default: inputfilename.out
  -t QUERY_TYPE          dig command query type, defalut: aaaa
  -c, --cname            write canonical name into hosts file
  -n THREAD_NUM          set the number of worker threads, default: 10
'''

def get_config():
    shortopts = 'hs:o:t:n:c'
    longopts = ['help', 'cname']

    try:
        optlist, args = getopt.gnu_getopt(sys.argv[1:], shortopts, longopts)
    except getopt.GetoptError as e:
        print e, '\n'
        print_help()
        sys.exit(1)

    global config
    for key, value in optlist:
        if key == '-s':
            config['dns'] = value
        elif key == '-o':
            config['outfile'] = value
        elif key == '-t':
            config['querytype'] = value
        elif key in ('-c', '--cname'):
            config['cname'] = True
        elif key == '-n':
            config['threadnum'] = int(value)
        elif key in ('-h', '--help'):
            print_help()
            sys.exit(0)

    if len(args) != 1:
        print "You must specify the input hosts file (only one)."
        sys.exit(1)

    config['infile'] = args[0]
    if config['outfile'] == '':
        config['outfile'] = config['infile'] + '.out'

def main():
    get_config()

    dig_path = '/usr/bin/dig'
    if not os.path.isfile(dig_path) or not os.access(dig_path, os.X_OK):
        print "It seems you don't have 'dig' command installed properly "\
              "on your system."
        sys.exit(2)

    global hosts
    try:
        with open(config['infile'], 'r') as infile:
            hosts = infile.readlines()
    except IOError as e:
        print e
        sys.exit(e.errno)

    if os.path.exists(config['outfile']):
        config['outfile'] += '.new'

    try:
        outfile = open(config['outfile'], 'w')
    except IOError as e:
        print e
        sys.exit(e.errno)

    print "Input: %s    Output: %s\n" % (config['infile'], config['outfile'])

    threads = []

    t = watcher_thread()
    t.start()
    threads.append(t)

    worker_num = config['threadnum']
    lines_num = len(hosts)

    lines_per_thread = lines_num / worker_num
    lines_remain = lines_num % worker_num

    start_pt = 0

    for _ in range(worker_num):
        if not running: break

        lines_for_thread = lines_per_thread

        if lines_for_thread == 0 and lines_remain == 0:
            break

        if lines_remain > 0:
            lines_for_thread += 1
            lines_remain -= 1

        t = worker_thread(start_pt, start_pt + lines_for_thread)
        start_pt += lines_for_thread

        t.start()
        threads.append(t)

    for t in threads:
        t.join()

    try:
        outfile.writelines(hosts)
    except IOError as e:
        print e
        sys.exit(e.errno)

    sys.exit(0)

if __name__ == '__main__':
    main()