lbry-sdk/lbrynet/core/utils.py

import base64
import datetime
import logging
import random
import socket
import string
import json

import pkg_resources

from lbryschema.claim import ClaimDict
from lbrynet.core.cryptoutils import get_lbry_hash_obj

# digest_size is in bytes, and blob hashes are hex encoded
blobhash_length = get_lbry_hash_obj().digest_size * 2

log = logging.getLogger(__name__)


# defining these time functions here allows for easier overriding in testing
def now():
    return datetime.datetime.now()


def utcnow():
    return datetime.datetime.utcnow()


def isonow():
    """Return utc now in isoformat with timezone"""
    return utcnow().isoformat() + 'Z'


def today():
    return datetime.datetime.today()


def timedelta(**kwargs):
    return datetime.timedelta(**kwargs)


def datetime_obj(*args, **kwargs):
    return datetime.datetime(*args, **kwargs)


def call_later(delay, func, *args, **kwargs):
    # Import here to ensure that it gets called after installing a reactor
    # see: http://twistedmatrix.com/documents/current/core/howto/choosing-reactor.html
    from twisted.internet import reactor
    return reactor.callLater(delay, func, *args, **kwargs)

def safe_start_looping_call(looping_call, interval_sec):
    if not looping_call.running:
        looping_call.start(interval_sec)

def safe_stop_looping_call(looping_call):
    if looping_call.running:
        looping_call.stop()

def generate_id(num=None):
    h = get_lbry_hash_obj()
    if num is not None:
        h.update(str(num))
    else:
        h.update(str(random.getrandbits(512)))
    return h.digest()


def is_valid_hashcharacter(char):
    return char in "0123456789abcdef"


def is_valid_blobhash(blobhash):
    """Checks whether the blobhash is the correct length and contains only
    valid characters (0-9, a-f)

    @param blobhash: string, the blobhash to check

    @return: True/False
    """
    return len(blobhash) == blobhash_length and all(is_valid_hashcharacter(l) for l in blobhash)


def version_is_greater_than(a, b):
    """Returns True if version a is more recent than version b"""
    return pkg_resources.parse_version(a) > pkg_resources.parse_version(b)


def deobfuscate(obfustacated):
    return base64.b64decode(obfustacated.decode('rot13'))


def obfuscate(plain):
    return base64.b64encode(plain).encode('rot13')


def check_connection(server="lbry.io", port=80, timeout=2):
    """Attempts to open a socket to server:port and returns True if successful."""
    log.debug('Checking connection to %s:%s', server, port)
    try:
        server = socket.gethostbyname(server)
        socket.create_connection((server, port), timeout)
        log.debug('Connection successful')
        return True
    except (socket.gaierror, socket.herror) as ex:
        log.warning("Failed to connect to %s:%s. Unable to resolve domain. Trying to bypass DNS",
                    server, port)
        try:
            server = "8.8.8.8"
            port = 53
            socket.create_connection((server, port), timeout)
            log.debug('Connection successful')
            return True
        except Exception as ex:
            log.error("Failed to connect to %s:%s. Maybe the internet connection is not working",
                      server, port)
            return False
    except Exception as ex:
        log.error("Failed to connect to %s:%s. Maybe the internet connection is not working",
                      server, port)
        return False


def random_string(length=10, chars=string.ascii_lowercase):
    return ''.join([random.choice(chars) for _ in range(length)])


def short_hash(hash_str):
    return hash_str[:6]


def get_sd_hash(stream_info):
    if not stream_info:
        return None
    if isinstance(stream_info, ClaimDict):
        return stream_info.source_hash
    path = ['claim', 'value', 'stream', 'source', 'source']
    result = safe_dict_descend(stream_info, *path)
    if not result:
        log.warn("Unable to get sd_hash via path %s" % path)
    return result


def json_dumps_pretty(obj, **kwargs):
    return json.dumps(obj, sort_keys=True, indent=2, separators=(',', ': '), **kwargs)


def safe_dict_descend(source, *path):
    """
    For when you want to do something like
    stream_info['claim']['value']['stream']['source']['source']"
    but don't trust that every last one of those keys exists
    """
    cur_source = source
    for path_entry in path:
        try:
            if path_entry not in cur_source:
                return None
        except TypeError:
            # This happens if we try to keep going along a path that isn't
            # a dictionary (see e.g. test_safe_dict_descend_typeerror)
            return None
        cur_source = cur_source[path_entry]
    return cur_source