Target calculation & chunk verification
This commit adds the code for FLO chunk verification. FLO chunk verification is different from Bitcoin chunk verification as the blockchain has 3 different target recalculation times. ie. 90 blocks at height 0->208440, 15 blocks at height 208440->426000 & 1 block further down Changes have also been maded such that chunk doesnt need to be saved in parts
This commit is contained in:
Vivek Teega
parent
d418976f5e
commit
085cd9919e
@ -31,7 +31,7 @@ from .util import bfh, bh2u
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HEADER_SIZE = 80 # bytes
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MAX_TARGET = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
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MAX_TARGET = 0x00000fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
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class MissingHeader(Exception):
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@ -176,19 +176,26 @@ class Blockchain(util.PrintError):
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def verify_chunk(self, index: int, data: bytes) -> None:
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num = len(data) // HEADER_SIZE
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start_height = index * 2016
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current_header = start_height = index * 2016
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prev_hash = self.get_hash(start_height - 1)
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target = self.get_target(index-1)
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headerLast = None
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headerFirst = None
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for i in range(num):
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target = self.get_target(current_header - 1, headerLast, headerFirst)
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height = start_height + i
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try:
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expected_header_hash = self.get_hash(height)
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except MissingHeader:
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expected_header_hash = None
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raw_header = data[i*HEADER_SIZE : (i+1)*HEADER_SIZE]
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header = deserialize_header(raw_header, index*2016 + i)
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header = deserialize_header(raw_header, current_header)
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self.verify_header(header, prev_hash, target, expected_header_hash)
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prev_hash = hash_header(header)
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headerLast = header
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difficulty_interval = self.DifficultyAdjustmentInterval(height)
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if height % difficulty_interval == 0:
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headerFirst = header
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current_header = current_header + 1
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def path(self):
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d = util.get_headers_dir(self.config)
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@ -330,33 +337,65 @@ class Blockchain(util.PrintError):
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raise MissingHeader(height)
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return hash_header(header)
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def get_target(self, index: int) -> int:
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def get_target(self, index: int, headerLast: dict=None, headerFirst: dict=None) -> int:
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# compute target from chunk x, used in chunk x+1
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if constants.net.TESTNET:
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return 0
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if index == -1:
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return MAX_TARGET
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# The range is first 90 blocks because FLO's block time was 90 blocks when it started
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if -1 <= index <= 88:
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return 0x1e0ffff0
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if index < len(self.checkpoints):
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h, t = self.checkpoints[index]
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return t
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# new target
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first = self.read_header(index * 2016)
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last = self.read_header(index * 2016 + 2015)
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if not first or not last:
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raise MissingHeader()
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bits = last.get('bits')
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target = self.bits_to_target(bits)
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nActualTimespan = last.get('timestamp') - first.get('timestamp')
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nTargetTimespan = 14 * 24 * 60 * 60
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nActualTimespan = max(nActualTimespan, nTargetTimespan // 4)
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nActualTimespan = min(nActualTimespan, nTargetTimespan * 4)
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new_target = min(MAX_TARGET, (target * nActualTimespan) // nTargetTimespan)
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return new_target
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if headerLast is None:
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headerLast = self.read_header(index)
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height = headerLast["block_height"]
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# check if the height passes is in range for retargeting
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if (height + 1) % self.DifficultyAdjustmentInterval(height + 1) != 0:
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return int(headerLast["bits"])
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if headerFirst is None:
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averagingInterval = self.AveragingInterval(height + 1)
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blockstogoback = averagingInterval - 1
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# print("Blocks to go back = " + str(blockstogoback))
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if (height + 1) != averagingInterval:
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blockstogoback = averagingInterval
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firstHeight = height - blockstogoback
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headerFirst = self.read_header(int(firstHeight))
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firstBlockTime = headerFirst["timestamp"]
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nMinActualTimespan = int(self.MinActualTimespan(int(headerLast["block_height"]) + 1))
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nMaxActualTimespan = int(self.MaxActualTimespan(int(headerLast["block_height"]) + 1))
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# Limit adjustment step
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nActualTimespan = headerLast["timestamp"] - firstBlockTime
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if nActualTimespan < nMinActualTimespan:
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nActualTimespan = nMinActualTimespan
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if nActualTimespan > nMaxActualTimespan:
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nActualTimespan = nMaxActualTimespan
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# Retarget
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bnNewBits = int(headerLast["bits"])
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bnNew = self.bits_to_target(bnNewBits)
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bnOld = bnNew
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# FLO: intermediate uint256 can overflow by 1 bit
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# const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);
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fShift = bnNew > MAX_TARGET - 1
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if (fShift):
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bnNew = bnNew >> 1
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bnNew = bnNew * nActualTimespan
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bnNew = bnNew / self.TargetTimespan(headerLast["block_height"] + 1)
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if fShift:
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bnNew = bnNew << 1
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if bnNew > MAX_TARGET:
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bnNew = MAX_TARGET
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bnNew = self.target_to_bits(int(bnNew))
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return bnNew
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def bits_to_target(self, bits: int) -> int:
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bitsN = (bits >> 24) & 0xff
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if not (bitsN >= 0x03 and bitsN <= 0x1d):
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raise Exception("First part of bits should be in [0x03, 0x1d]")
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if not (bitsN >= 0x03 and bitsN <= 0x1e):
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raise BaseException("First part of bits should be in [0x03, 0x1e]")
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bitsBase = bits & 0xffffff
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if not (bitsBase >= 0x8000 and bitsBase <= 0x7fffff):
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raise Exception("Second part of bits should be in [0x8000, 0x7fffff]")
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@ -418,6 +457,61 @@ class Blockchain(util.PrintError):
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cp.append((h, target))
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return cp
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def AveragingInterval(self, height):
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# V1
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if height < constants.net.nHeight_Difficulty_Version2:
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return constants.net.nAveragingInterval_Version1
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# V2
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elif height < constants.net.nHeight_Difficulty_Version3:
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return constants.net.nAveragingInterval_Version2
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# V3
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else:
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return constants.net.nAveragingInterval_Version3
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def MinActualTimespan(self, height):
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averagingTargetTimespan = self.AveragingInterval(height) * constants.net.nPowTargetSpacing
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# V1
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if height < constants.net.nHeight_Difficulty_Version2:
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return int(averagingTargetTimespan * (100 - constants.net.nMaxAdjustUp_Version1) / 100)
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# V2
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elif height < constants.net.nHeight_Difficulty_Version3:
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return int(averagingTargetTimespan * (100 - constants.net.nMaxAdjustUp_Version2) / 100)
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# V3
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else:
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return int(averagingTargetTimespan * (100 - constants.net.nMaxAdjustUp_Version3) / 100)
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def MaxActualTimespan(self, height):
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averagingTargetTimespan = self.AveragingInterval(height) * constants.net.nPowTargetSpacing
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# V1
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if height < constants.net.nHeight_Difficulty_Version2:
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return int(averagingTargetTimespan * (100 + constants.net.nMaxAdjustDown_Version1) / 100)
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# V2
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elif height < constants.net.nHeight_Difficulty_Version3:
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return int(averagingTargetTimespan * (100 + constants.net.nMaxAdjustDown_Version2) / 100)
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# V3
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else:
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return int(averagingTargetTimespan * (100 + constants.net.nMaxAdjustDown_Version3) / 100)
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def TargetTimespan(self, height):
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# V1
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if height < constants.net.nHeight_Difficulty_Version2:
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return constants.net.nTargetTimespan_Version1
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# V2
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if height < constants.net.nHeight_Difficulty_Version3:
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return constants.net.nAveragingInterval_Version2 * constants.net.nPowTargetSpacing
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# V3
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return constants.net.nAveragingInterval_Version3 * constants.net.nPowTargetSpacing
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def DifficultyAdjustmentInterval(self, height):
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# V1
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if height < constants.net.nHeight_Difficulty_Version2:
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return constants.net.nInterval_Version1
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# V2
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if height < constants.net.nHeight_Difficulty_Version3:
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return constants.net.nInterval_Version2
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# V3
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return constants.net.nInterval_Version3
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def check_header(header: dict) -> Optional[Blockchain]:
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if type(header) is not dict:
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@ -18,7 +18,6 @@ _sym_db = _symbol_database.Default()
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DESCRIPTOR = _descriptor.FileDescriptor(
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name='paymentrequest.proto',
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package='payments',
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syntax='proto2',
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serialized_pb=_b('\n\x14paymentrequest.proto\x12\x08payments\"+\n\x06Output\x12\x11\n\x06\x61mount\x18\x01 \x01(\x04:\x01\x30\x12\x0e\n\x06script\x18\x02 \x02(\x0c\"\xa3\x01\n\x0ePaymentDetails\x12\x15\n\x07network\x18\x01 \x01(\t:\x04main\x12!\n\x07outputs\x18\x02 \x03(\x0b\x32\x10.payments.Output\x12\x0c\n\x04time\x18\x03 \x02(\x04\x12\x0f\n\x07\x65xpires\x18\x04 \x01(\x04\x12\x0c\n\x04memo\x18\x05 \x01(\t\x12\x13\n\x0bpayment_url\x18\x06 \x01(\t\x12\x15\n\rmerchant_data\x18\x07 \x01(\x0c\"\x95\x01\n\x0ePaymentRequest\x12\"\n\x17payment_details_version\x18\x01 \x01(\r:\x01\x31\x12\x16\n\x08pki_type\x18\x02 \x01(\t:\x04none\x12\x10\n\x08pki_data\x18\x03 \x01(\x0c\x12\"\n\x1aserialized_payment_details\x18\x04 \x02(\x0c\x12\x11\n\tsignature\x18\x05 \x01(\x0c\"\'\n\x10X509Certificates\x12\x13\n\x0b\x63\x65rtificate\x18\x01 \x03(\x0c\"i\n\x07Payment\x12\x15\n\rmerchant_data\x18\x01 \x01(\x0c\x12\x14\n\x0ctransactions\x18\x02 \x03(\x0c\x12#\n\trefund_to\x18\x03 \x03(\x0b\x32\x10.payments.Output\x12\x0c\n\x04memo\x18\x04 \x01(\t\">\n\nPaymentACK\x12\"\n\x07payment\x18\x01 \x02(\x0b\x32\x11.payments.Payment\x12\x0c\n\x04memo\x18\x02 \x01(\tB(\n\x1eorg.bitcoin.protocols.paymentsB\x06Protos')
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)
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_sym_db.RegisterFileDescriptor(DESCRIPTOR)
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@ -55,7 +54,6 @@ _OUTPUT = _descriptor.Descriptor(
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],
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options=None,
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is_extendable=False,
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syntax='proto2',
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extension_ranges=[],
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oneofs=[
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],
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@ -128,7 +126,6 @@ _PAYMENTDETAILS = _descriptor.Descriptor(
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],
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options=None,
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is_extendable=False,
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syntax='proto2',
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extension_ranges=[],
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oneofs=[
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],
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@ -187,7 +184,6 @@ _PAYMENTREQUEST = _descriptor.Descriptor(
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],
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options=None,
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is_extendable=False,
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syntax='proto2',
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extension_ranges=[],
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oneofs=[
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],
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@ -218,7 +214,6 @@ _X509CERTIFICATES = _descriptor.Descriptor(
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],
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options=None,
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is_extendable=False,
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syntax='proto2',
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extension_ranges=[],
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oneofs=[
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],
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@ -270,7 +265,6 @@ _PAYMENT = _descriptor.Descriptor(
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],
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options=None,
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is_extendable=False,
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syntax='proto2',
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extension_ranges=[],
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oneofs=[
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],
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@ -308,7 +302,6 @@ _PAYMENTACK = _descriptor.Descriptor(
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],
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options=None,
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is_extendable=False,
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syntax='proto2',
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extension_ranges=[],
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oneofs=[
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],
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@ -362,8 +362,7 @@ if __name__ == '__main__':
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args = parser.parse_args()
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# config is an object passed to the various constructors (wallet, interface, gui)
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#if is_android:
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if True:
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if is_android:
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config_options = {
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'verbosity': '',
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'cmd': 'gui',
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