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#!/usr/bin/env python3
# BlockStore: a helper class that keeps a map of blocks and implements
# helper functions for responding to getheaders and getdata,
# and for constructing a getheaders message
#
from .mininode import *
from io import BytesIO
import dbm.ndbm
class BlockStore(object):
def __init__(self, datadir):
self.blockDB = dbm.ndbm.open(datadir + "/blocks", 'c')
self.currentBlock = 0
self.headers_map = dict()
def close(self):
self.blockDB.close()
def get(self, blockhash):
serialized_block = None
try:
serialized_block = self.blockDB[repr(blockhash)]
except KeyError:
return None
f = BytesIO(serialized_block)
ret = CBlock()
ret.deserialize(f)
ret.calc_sha256()
return ret
def get_header(self, blockhash):
try:
return self.headers_map[blockhash]
except KeyError:
return None
# Note: this pulls full blocks out of the database just to retrieve
# the headers -- perhaps we could keep a separate data structure
# to avoid this overhead.
def headers_for(self, locator, hash_stop, current_tip=None):
if current_tip is None:
current_tip = self.currentBlock
current_block_header = self.get_header(current_tip)
if current_block_header is None:
return None
response = msg_headers()
headersList = [ current_block_header ]
maxheaders = 2000
while (headersList[0].sha256 not in locator.vHave):
prevBlockHash = headersList[0].hashPrevBlock
prevBlockHeader = self.get_header(prevBlockHash)
if prevBlockHeader is not None:
headersList.insert(0, prevBlockHeader)
else:
break
headersList = headersList[:maxheaders] # truncate if we have too many
hashList = [x.sha256 for x in headersList]
index = len(headersList)
if (hash_stop in hashList):
index = hashList.index(hash_stop)+1
response.headers = headersList[:index]
return response
def add_block(self, block):
block.calc_sha256()
try:
self.blockDB[repr(block.sha256)] = bytes(block.serialize())
except TypeError as e:
print("Unexpected error: ", sys.exc_info()[0], e.args)
self.currentBlock = block.sha256
self.headers_map[block.sha256] = CBlockHeader(block)
def add_header(self, header):
self.headers_map[header.sha256] = header
def get_blocks(self, inv):
responses = []
for i in inv:
if (i.type == 2): # MSG_BLOCK
block = self.get(i.hash)
if block is not None:
responses.append(msg_block(block))
return responses
def get_locator(self, current_tip=None):
if current_tip is None:
current_tip = self.currentBlock
r = []
counter = 0
step = 1
lastBlock = self.get(current_tip)
while lastBlock is not None:
r.append(lastBlock.hashPrevBlock)
for i in range(step):
lastBlock = self.get(lastBlock.hashPrevBlock)
if lastBlock is None:
break
counter += 1
if counter > 10:
step *= 2
locator = CBlockLocator()
locator.vHave = r
return locator
class TxStore(object):
def __init__(self, datadir):
self.txDB = dbm.ndbm.open(datadir + "/transactions", 'c')
def close(self):
self.txDB.close()
def get(self, txhash):
serialized_tx = None
try:
serialized_tx = self.txDB[repr(txhash)]
except KeyError:
return None
f = BytesIO(serialized_tx)
ret = CTransaction()
ret.deserialize(f)
ret.calc_sha256()
return ret
def add_transaction(self, tx):
tx.calc_sha256()
try:
self.txDB[repr(tx.sha256)] = bytes(tx.serialize())
except TypeError as e:
print("Unexpected error: ", sys.exc_info()[0], e.args)
def get_transactions(self, inv):
responses = []
for i in inv:
if (i.type == 1): # MSG_TX
tx = self.get(i.hash)
if tx is not None:
responses.append(msg_tx(tx))
return responses
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