Onionr/src/communicatorutils/lookupblocks.py

'''
    Onionr - Private P2P Communication

    Lookup new blocks with the communicator using a random connected peer
'''
'''
    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
    the Free Software Foundation, either version 3 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, see <https://www.gnu.org/licenses/>.
'''
from gevent import time

import logger, onionrproofs
from onionrutils import stringvalidators, epoch
from communicator import peeraction, onlinepeers
from coredb import blockmetadb
from utils import reconstructhash
from onionrblocks import onionrblacklist
import onionrexceptions
blacklist = onionrblacklist.OnionrBlackList()
def lookup_blocks_from_communicator(comm_inst):
    logger.info('Looking up new blocks')
    tryAmount = 2
    newBlocks = ''
    existingBlocks = blockmetadb.get_block_list() # List of existing saved blocks
    triedPeers = [] # list of peers we've tried this time around
    maxBacklog = 1560 # Max amount of *new* block hashes to have already in queue, to avoid memory exhaustion
    lastLookupTime = 0 # Last time we looked up a particular peer's list
    new_block_count = 0
    for i in range(tryAmount):
        listLookupCommand = 'getblocklist' # This is defined here to reset it each time
        if len(comm_inst.blockQueue) >= maxBacklog:
            break
        if not comm_inst.isOnline:
            break
        # check if disk allocation is used
        if comm_inst.storage_counter.is_full():
            logger.debug('Not looking up new blocks due to maximum amount of allowed disk space used')
            break
        try:
            # select random online peer
            peer = onlinepeers.pick_online_peer(comm_inst)
        except onionrexceptions.OnlinePeerNeeded:
            time.sleep(1)
            continue
        # if we've already tried all the online peers this time around, stop
        if peer in triedPeers:
            if len(comm_inst.onlinePeers) == len(triedPeers):
                break
            else:
                continue
        triedPeers.append(peer)

        # Get the last time we looked up a peer's stamp to only fetch blocks since then.
        # Saved in memory only for privacy reasons
        try:
            lastLookupTime = comm_inst.dbTimestamps[peer]
        except KeyError:
            lastLookupTime = 0
        else:
            listLookupCommand += '?date=%s' % (lastLookupTime,)
        try:
            newBlocks = peeraction.peer_action(comm_inst, peer, listLookupCommand) # get list of new block hashes
        except Exception as error:
            logger.warn('Could not get new blocks from %s.' % peer, error = error)
            newBlocks = False
        else:
            comm_inst.dbTimestamps[peer] = epoch.get_rounded_epoch(roundS=60)
        if newBlocks != False:
            # if request was a success
            for i in newBlocks.split('\n'):
                if stringvalidators.validate_hash(i):
                    i = reconstructhash.reconstruct_hash(i)
                    # if newline seperated string is valid hash
                    if not i in existingBlocks:
                        # if block does not exist on disk and is not already in block queue
                        if i not in comm_inst.blockQueue:
                            if onionrproofs.hashMeetsDifficulty(i) and not blacklist.inBlacklist(i):
                                if len(comm_inst.blockQueue) <= 1000000:
                                    comm_inst.blockQueue[i] = [peer] # add blocks to download queue
                                    new_block_count += 1
                        else:
                            if peer not in comm_inst.blockQueue[i]:
                                if len(comm_inst.blockQueue[i]) < 10:
                                    comm_inst.blockQueue[i].append(peer)
    if new_block_count > 0:
        block_string = ""
        if new_block_count > 1:
            block_string = "s"
        logger.info('Discovered %s new block%s' % (new_block_count, block_string), terminal=True)
        comm_inst.download_blocks_timer.count = int(comm_inst.download_blocks_timer.frequency * 0.99)
    comm_inst.decrementThreadCount('lookup_blocks_from_communicator')
    return