crawl.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# crawl.py - Greenlets-based Bitcoin network crawler.
#
# Copyright (c) 2014 Addy Yeow Chin Heng <ayeowch@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

"""
Greenlets-based Bitcoin network crawler.
"""

from gevent import monkey
monkey.patch_all()

import gevent
import json
import logging
import os
import redis
import redis.connection
import socket
import sys
import time
from collections import Counter
from ConfigParser import ConfigParser
from ipaddress import ip_network

from protocol import ProtocolError, ConnectionError, Connection, DEFAULT_PORT

redis.connection.socket = gevent.socket

# Redis connection setup
REDIS_SOCKET = os.environ.get('REDIS_SOCKET', "/tmp/redis.sock")
REDIS_PASSWORD = os.environ.get('REDIS_PASSWORD', None)
REDIS_CONN = redis.StrictRedis(unix_socket_path=REDIS_SOCKET,
                               password=REDIS_PASSWORD)

SETTINGS = {}


def enumerate_node(redis_pipe, addr_msgs, now):
    """
    Adds all peering nodes with max. age of 24 hours into the crawl set.
    """
    peers = 0

    for addr_msg in addr_msgs:
        if 'addr_list' in addr_msg:
            for peer in addr_msg['addr_list']:
                age = now - peer['timestamp']  # seconds

                # Add peering node with age <= 24 hours into crawl set
                if age >= 0 and age <= SETTINGS['max_age']:
                    address = peer['ipv4'] if peer['ipv4'] else peer['ipv6']
                    port = peer['port'] if peer['port'] > 0 else DEFAULT_PORT
                    if address in SETTINGS['exclude_nodes']:
                        logging.debug("Exclude: {}".format(address))
                        continue
                    redis_pipe.sadd('pending', (address, port))
                    peers += 1

    return peers


def connect(redis_conn, key):
    """
    Establishes connection with a node to:
    1) Send version message
    2) Receive version and verack message
    3) Send getaddr message
    4) Receive addr message containing list of peering nodes
    Stores state and height for node in Redis.
    """
    handshake_msgs = []
    addr_msgs = []

    redis_conn.hset(key, 'state', "")  # Set Redis hash for a new node

    (address, port) = key[5:].split("-", 1)
    height = redis_conn.get('height')
    if height is None:
        height = 0
    else:
        height = int(height)

    connection = Connection((address, int(port)),
                            socket_timeout=SETTINGS['socket_timeout'],
                            user_agent=SETTINGS['user_agent'],
                            height=height)
    try:
        logging.debug("Connecting to {}".format(connection.to_addr))
        connection.open()
        handshake_msgs = connection.handshake()
        addr_msgs = connection.getaddr()
    except (ProtocolError, ConnectionError, socket.error) as err:
        logging.debug("{}: {}".format(connection.to_addr, err))
    finally:
        connection.close()

    gevent.sleep(0.3)
    redis_pipe = redis_conn.pipeline()
    if len(handshake_msgs) > 0:
        height_key = "height:{}-{}".format(address, port)
        redis_pipe.setex(height_key, SETTINGS['max_age'],
                         handshake_msgs[0].get('height', 0))
        now = int(time.time())
        peers = enumerate_node(redis_pipe, addr_msgs, now)
        logging.debug("{} Peers: {}".format(connection.to_addr, peers))
        redis_pipe.hset(key, 'state', "up")
    redis_pipe.execute()


def dump(timestamp, nodes):
    """
    Dumps data for reachable nodes into timestamp-prefixed JSON file and
    returns most common height from the nodes.
    """
    json_data = []

    for node in nodes:
        (address, port) = node[5:].split("-", 1)
        try:
            height = int(REDIS_CONN.get("height:{}-{}".format(address, port)))
        except TypeError:
            logging.warning("height:{}-{} missing".format(address, port))
            height = 0
        json_data.append([address, int(port), height])

    json_output = os.path.join(SETTINGS['crawl_dir'],
                               "{}.json".format(timestamp))
    open(json_output, 'w').write(json.dumps(json_data))
    logging.info("Wrote {}".format(json_output))

    return Counter([node[-1] for node in json_data]).most_common(1)[0][0]


def restart(timestamp):
    """
    Dumps data for the reachable nodes into a JSON file.
    Loads all reachable nodes from Redis into the crawl set.
    Removes keys for all nodes from current crawl.
    Updates number of reachable nodes and most common height in Redis.
    """
    nodes = []  # Reachable nodes

    keys = REDIS_CONN.keys('node:*')
    logging.debug("Keys: {}".format(len(keys)))

    redis_pipe = REDIS_CONN.pipeline()
    for key in keys:
        state = REDIS_CONN.hget(key, 'state')
        if state == "up":
            nodes.append(key)
            (address, port) = key[5:].split("-", 1)
            redis_pipe.sadd('pending', (address, int(port)))
        redis_pipe.delete(key)
    redis_pipe.execute()

    reachable_nodes = len(nodes)
    logging.info("Reachable nodes: {}".format(reachable_nodes))
    REDIS_CONN.lpush('nodes', (timestamp, reachable_nodes))

    height = dump(timestamp, nodes)
    REDIS_CONN.set('height', height)
    logging.info("Height: {}".format(height))


def cron():
    """
    Assigned to a worker to perform the following tasks periodically to
    maintain a continuous crawl:
    1) Reports the current number of nodes in crawl set
    2) Initiates a new crawl once the crawl set is empty
    """
    start = int(time.time())

    while True:
        pending_nodes = REDIS_CONN.scard('pending')
        logging.info("Pending: {}".format(pending_nodes))

        if pending_nodes == 0:
            REDIS_CONN.set('crawl:master:state', "starting")
            now = int(time.time())
            elapsed = now - start
            REDIS_CONN.set('elapsed', elapsed)
            logging.info("Elapsed: {}".format(elapsed))
            logging.info("Restarting")
            restart(now)
            start = int(time.time())
            REDIS_CONN.set('crawl:master:state', "running")

        gevent.sleep(SETTINGS['cron_delay'])


def task():
    """
    Assigned to a worker to retrieve (pop) a node from the crawl set and
    attempt to establish connection with a new node.
    """
    redis_conn = redis.StrictRedis(unix_socket_path=REDIS_SOCKET,
                                   password=REDIS_PASSWORD)

    while True:
        if not SETTINGS['master']:
            while REDIS_CONN.get('crawl:master:state') != "running":
                gevent.sleep(SETTINGS['socket_timeout'])

        node = redis_conn.spop('pending')  # Pop random node from set
        if node is None:
            gevent.sleep(1)
            continue

        node = eval(node)  # Convert string from Redis to tuple

        # Skip IPv6 node
        if ":" in node[0] and not SETTINGS['ipv6']:
            continue

        key = "node:{}-{}".format(node[0], node[1])
        if redis_conn.exists(key):
            continue

        connect(redis_conn, key)


def set_pending():
    """
    Initializes pending set in Redis with a list of reachable nodes from DNS
    seeders to bootstrap the crawler.
    """
    for seeder in SETTINGS['seeders']:
        nodes = []
        try:
            nodes = socket.getaddrinfo(seeder, None)
        except socket.gaierror as err:
            logging.warning("{}".format(err))
            continue
        for node in nodes:
            address = node[-1][0]
            if address in SETTINGS['exclude_nodes']:
                logging.debug("Exclude: {}".format(address))
                continue
            logging.debug("{}: {}".format(seeder, address))
            REDIS_CONN.sadd('pending', (address, DEFAULT_PORT))


def init_settings(argv):
    """
    Populates SETTINGS with key-value pairs from configuration file.
    """
    conf = ConfigParser()
    conf.read(argv[1])
    SETTINGS['logfile'] = conf.get('crawl', 'logfile')
    SETTINGS['seeders'] = conf.get('crawl', 'seeders').strip().split("\n")
    SETTINGS['workers'] = conf.getint('crawl', 'workers')
    SETTINGS['debug'] = conf.getboolean('crawl', 'debug')
    SETTINGS['user_agent'] = conf.get('crawl', 'user_agent')
    SETTINGS['socket_timeout'] = conf.getint('crawl', 'socket_timeout')
    SETTINGS['cron_delay'] = conf.getint('crawl', 'cron_delay')
    SETTINGS['max_age'] = conf.getint('crawl', 'max_age')
    SETTINGS['ipv6'] = conf.getboolean('crawl', 'ipv6')
    exclude_nodes = conf.get('crawl', 'exclude_nodes').strip().split("\n")
    exclude_networks = conf.get('crawl',
                                'exclude_networks').strip().split("\n")
    for network in exclude_networks:
        exclude_nodes.extend(
            [str(address) for address in list(ip_network(unicode(network)))])
    SETTINGS['exclude_nodes'] = set(exclude_nodes)
    SETTINGS['crawl_dir'] = conf.get('crawl', 'crawl_dir')
    if not os.path.exists(SETTINGS['crawl_dir']):
        os.makedirs(SETTINGS['crawl_dir'])
    SETTINGS['master'] = argv[2] == "master"


def main(argv):
    if len(argv) < 3 or not os.path.exists(argv[1]):
        print("Usage: crawl.py [config] [master|slave]")
        return 1

    # Initialize global settings
    init_settings(argv)

    # Initialize logger
    loglevel = logging.INFO
    if SETTINGS['debug']:
        loglevel = logging.DEBUG

    logformat = ("[%(process)d] %(asctime)s,%(msecs)05.1f %(levelname)s "
                 "(%(funcName)s) %(message)s")
    logging.basicConfig(level=loglevel,
                        format=logformat,
                        filename=SETTINGS['logfile'],
                        filemode='a')
    print("Writing output to {}, press CTRL+C to terminate..".format(
          SETTINGS['logfile']))

    if SETTINGS['master']:
        REDIS_CONN.set('crawl:master:state', "starting")
        logging.info("Removing all keys")
        keys = REDIS_CONN.keys('node:*')
        redis_pipe = REDIS_CONN.pipeline()
        for key in keys:
            redis_pipe.delete(key)
        redis_pipe.delete('pending')
        redis_pipe.execute()
        set_pending()

    # Spawn workers (greenlets) including one worker reserved for cron tasks
    workers = []
    if SETTINGS['master']:
        workers.append(gevent.spawn(cron))
    for _ in xrange(SETTINGS['workers'] - len(workers)):
        workers.append(gevent.spawn(task))
    logging.info("Workers: {}".format(len(workers)))
    gevent.joinall(workers)

    return 0


if __name__ == '__main__':
    sys.exit(main(sys.argv))