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<?php |
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namespace Blocktrail\SDK; |
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use BitWasp\Bitcoin\Script\ScriptFactory; |
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use BitWasp\Bitcoin\Script\ScriptType; |
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use BitWasp\Bitcoin\Crypto\EcAdapter\Key\PublicKeyInterface; |
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use \BitWasp\Bitcoin\Script\ScriptInfo\Multisig; |
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use \BitWasp\Bitcoin\Script\ScriptInfo\PayToPubKey; |
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use \BitWasp\Bitcoin\Script\Classifier\OutputClassifier; |
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use BitWasp\Bitcoin\Script\ScriptInterface; |
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use BitWasp\Bitcoin\Transaction\TransactionOutputInterface; |
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class SizeEstimation |
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{ |
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const SIZE_DER_SIGNATURE = 72; |
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const SIZE_V0_P2WSH = 36; |
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/** |
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* @param bool $compressed |
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* @return int |
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*/ |
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public static function getPublicKeySize($compressed = true) { |
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return $compressed ? PublicKeyInterface::LENGTH_COMPRESSED : PublicKeyInterface::LENGTH_UNCOMPRESSED; |
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} |
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/** |
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* @param int $length |
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* @return int |
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*/ |
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public static function getLengthOfScriptLengthElement($length) { |
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if ($length < 75) { |
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return 1; |
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} else if ($length <= 0xff) { |
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return 2; |
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} else if ($length <= 0xffff) { |
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return 3; |
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1 |
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} else if ($length <= 0xffffffff) { |
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return 5; |
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} else { |
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throw new \RuntimeException('Size of pushdata too large'); |
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} |
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} |
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/** |
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* @param int $length |
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* @return int |
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*/ |
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37 |
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public static function getLengthOfVarInt($length) { |
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37 |
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if ($length < 253) { |
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return 1; |
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} else if ($length < 65535) { |
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$num_bytes = 2; |
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} else if ($length < 4294967295) { |
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$num_bytes = 4; |
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} else if ($length < 18446744073709551615) { |
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$num_bytes = 8; |
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} else { |
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throw new \InvalidArgumentException("Invalid decimal"); |
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} |
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return 1 + $num_bytes; |
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} |
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/** |
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* @param array $vectorSizes |
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* @return int|mixed |
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*/ |
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public static function getLengthOfVector(array $vectorSizes) { |
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$vectorSize = self::getLengthOfVarInt(count($vectorSizes)); |
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foreach ($vectorSizes as $size) { |
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$vectorSize += self::getLengthOfVarInt($size) + $size; |
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} |
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return $vectorSize; |
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} |
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/** |
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* @param Multisig $multisig |
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* @return array - first is array of stack sizes, second is script len |
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*/ |
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public static function estimateMultisigStackSize(Multisig $multisig) { |
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$stackSizes = [0]; |
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for ($i = 0; $i < $multisig->getRequiredSigCount(); $i++) { |
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$stackSizes[] = self::SIZE_DER_SIGNATURE; |
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} |
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$scriptSize = 1; // OP_$m |
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$keys = $multisig->getKeyBuffers(); |
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for ($i = 0, $n = $multisig->getKeyCount(); $i < $n; $i++) { |
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$scriptSize += 1 + $keys[$i]->getSize(); |
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} |
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$scriptSize += 1 + 1; // OP_$n OP_CHECKMULTISIG |
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return [$stackSizes, $scriptSize]; |
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} |
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/** |
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* @param PayToPubKey $info |
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* @return array - first is array of stack sizes, second is script len |
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*/ |
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public static function estimateP2PKStackSize(PayToPubKey $info) { |
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$stackSizes = [self::SIZE_DER_SIGNATURE]; |
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$scriptSize = 1 + $info->getKeyBuffer()->getSize(); // PUSHDATA[<75] PUBLICKEY |
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$scriptSize += 1; // OP_CHECKSIG |
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return [$stackSizes, $scriptSize]; |
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} |
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/** |
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* @param bool $isCompressed |
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* @return array - first is array of stack sizes, second is script len |
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*/ |
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public static function estimateP2PKHStackSize($isCompressed = true) { |
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$pubKeySize = self::getPublicKeySize($isCompressed); |
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$stackSizes = [self::SIZE_DER_SIGNATURE, $pubKeySize]; |
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$scriptSize = 1 + 1 + 1 + 20 + 1 + 1; |
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return [$stackSizes, $scriptSize]; |
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} |
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/** |
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* @param array $stackSizes - array of integer size of a value (for scriptSig or witness) |
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* @param bool $isWitness |
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* @param ScriptInterface $redeemScript |
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* @param ScriptInterface $witnessScript |
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* @return array |
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*/ |
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public static function estimateSizeForStack(array $stackSizes, $isWitness, ScriptInterface $redeemScript = null, ScriptInterface $witnessScript = null) { |
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assert(($witnessScript === null) || $isWitness); |
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if ($isWitness) { |
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$scriptSigSizes = []; |
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$witnessSizes = $stackSizes; |
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if ($witnessScript instanceof ScriptInterface) { |
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$witnessSizes[] = $witnessScript->getBuffer()->getSize(); |
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} |
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} else { |
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$scriptSigSizes = $stackSizes; |
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$witnessSizes = []; |
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} |
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if ($redeemScript instanceof ScriptInterface) { |
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$scriptSigSizes[] = $redeemScript->getBuffer()->getSize(); |
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} |
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$scriptSigSize = 0; |
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foreach ($scriptSigSizes as $size) { |
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$len = self::getLengthOfScriptLengthElement($size); |
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$scriptSigSize += $len; |
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$scriptSigSize += $size; |
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} |
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// Make sure to count the CScriptBase length prefix.. |
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$scriptSigSize += self::getLengthOfVarInt($scriptSigSize); |
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// make sure this is set to 0 when not used. |
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// Summing WitnessSize is used in addition to $withWitness |
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// because a tx without witnesses _cannot_ use witness serialization |
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// total witnessSize = 0 means don't use that format |
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$witnessSize = 0; |
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if (count($witnessSizes) > 0) { |
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// witness has a prefix indicating `n` elements in vector |
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$witnessSize = self::getLengthOfVector($witnessSizes); |
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} |
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return [$scriptSigSize, $witnessSize]; |
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} |
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/** |
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* @param ScriptInterface $script - not the scriptPubKey, might be SPK,RS,WS |
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* @param ScriptInterface|null $redeemScript |
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* @param ScriptInterface $witnessScript |
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* @param bool $isWitness |
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* @return array |
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*/ |
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public static function estimateInputFromScripts(ScriptInterface $script, ScriptInterface $redeemScript = null, ScriptInterface $witnessScript = null, $isWitness) { |
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assert($witnessScript === null || $isWitness); |
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$classifier = new OutputClassifier(); |
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if ($classifier->isMultisig($script)) { |
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list ($stackSizes, ) = SizeEstimation::estimateMultisigStackSize(new Multisig($script)); |
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} else if ($classifier->isPayToPublicKey($script)) { |
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list ($stackSizes, ) = SizeEstimation::estimateP2PKStackSize(new PayToPubKey($script)); |
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} else if ($classifier->isPayToPublicKeyHash($script)) { |
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// defaults to compressed, tough luck |
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list ($stackSizes, ) = SizeEstimation::estimateP2PKHStackSize(); |
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} else { |
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throw new \InvalidArgumentException("Unsupported script type"); |
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} |
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return self::estimateSizeForStack($stackSizes, $isWitness, $redeemScript, $witnessScript); |
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} |
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/** |
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* @param UTXO $utxo |
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* @return array |
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*/ |
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public static function estimateUtxo(UTXO $utxo) { |
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return self::estimateUtxoFromScripts($utxo->scriptPubKey, $utxo->redeemScript, $utxo->witnessScript); |
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} |
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/** |
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* @param ScriptInterface $scriptPubKey |
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* @param ScriptInterface $redeemScript |
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* @param ScriptInterface $witnessScript |
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* @return array |
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*/ |
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public static function estimateUtxoFromScripts( |
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ScriptInterface $scriptPubKey, |
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ScriptInterface $redeemScript = null, |
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ScriptInterface $witnessScript = null |
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) { |
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$classifier = new OutputClassifier(); |
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$decodePK = $classifier->decode($scriptPubKey); |
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$witness = false; |
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if ($decodePK->getType() === ScriptType::P2SH) { |
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if (null === $redeemScript) { |
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throw new \RuntimeException("Can't estimate, missing redeem script"); |
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} |
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$decodePK = $classifier->decode($redeemScript); |
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} |
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220
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if ($decodePK->getType() === ScriptType::P2WKH) { |
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$scriptSitu = ScriptFactory::scriptPubKey()->p2pkh($decodePK->getSolution()); |
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3 |
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$decodePK = $classifier->decode($scriptSitu); |
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$witness = true; |
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} else if ($decodePK->getType() === ScriptType::P2WSH) { |
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if (null === $witnessScript) { |
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throw new \RuntimeException("Can't estimate, missing witness script"); |
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} |
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$decodePK = $classifier->decode($witnessScript); |
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$witness = true; |
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} |
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if (!in_array($decodePK->getType(), [ScriptType::MULTISIG, ScriptType::P2PKH, ScriptType::P2PK])) { |
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throw new \RuntimeException("Unsupported script type"); |
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} |
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235
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236
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20 |
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$script = $decodePK->getScript(); |
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list ($scriptSig, $witness) = SizeEstimation::estimateInputFromScripts($script, $redeemScript, $witnessScript, $witness); |
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239
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return [ |
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20 |
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"scriptSig" => $scriptSig, |
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"witness" => $witness, |
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]; |
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} |
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245
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/** |
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246
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* @param UTXO[] $utxos |
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247
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* @param bool $withWitness |
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248
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* @return integer |
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249
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*/ |
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250
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15 |
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public static function estimateInputsSize(array $utxos, $withWitness) { |
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251
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15 |
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$inputSize = 0; |
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252
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15 |
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$witnessSize = 0; |
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253
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15 |
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foreach ($utxos as $utxo) { |
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254
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15 |
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$estimate = SizeEstimation::estimateUtxo($utxo); |
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255
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15 |
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$inputSize += 32 + 4 + 4; |
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256
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15 |
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$inputSize += $estimate['scriptSig']; |
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257
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15 |
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if ($withWitness) { |
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15 |
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$witnessSize += $estimate['witness']; |
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} |
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260
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} |
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261
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262
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15 |
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if ($withWitness && $witnessSize != 0) { |
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263
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9 |
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$inputSize += $witnessSize; |
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264
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9 |
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$inputSize += 2; // flag bytes |
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265
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} |
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266
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267
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15 |
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return $inputSize; |
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268
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} |
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270
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/** |
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271
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* @param array $outputs |
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272
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* @return int |
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273
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*/ |
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274
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15 |
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public static function estimateOutputsSize(array $outputs) { |
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275
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15 |
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$outputSize = 0; |
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276
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15 |
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foreach ($outputs as $output) { |
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277
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13 |
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$size = 8; |
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278
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279
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13 |
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$scriptSize = null; |
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280
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13 |
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if ($output instanceof TransactionOutputInterface) { |
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281
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6 |
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$scriptSize = $output->getScript()->getBuffer()->getSize(); |
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282
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} else { |
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283
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11 |
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if (isset($output['scriptPubKey'])) { |
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284
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11 |
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if ($output['scriptPubKey'] instanceof ScriptInterface) { |
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285
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11 |
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$scriptSize = $output['scriptPubKey']->getBuffer()->getSize(); |
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286
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} else { |
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287
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11 |
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$scriptSize = strlen($output['scriptPubKey']) / 2; |
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288
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} |
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289
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} else { |
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290
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6 |
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$scriptSize = 25; |
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291
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} |
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292
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} |
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293
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294
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13 |
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$size += SizeEstimation::getLengthOfVarInt($scriptSize) + $scriptSize; |
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295
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13 |
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$outputSize += $size; |
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296
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} |
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297
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15 |
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return $outputSize; |
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298
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} |
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299
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300
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/** |
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301
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* @param UTXO[] $utxos |
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302
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* @param array $outputs |
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303
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* @return int |
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304
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*/ |
|
305
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15 |
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public static function estimateVsize(array $utxos, array $outputs) { |
|
306
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15 |
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return (int)ceil(self::estimateWeight($utxos, $outputs) / 4); |
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307
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} |
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308
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309
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/** |
|
310
|
|
|
* @param UTXO[] $utxos |
|
311
|
|
|
* @param array $outputs |
|
312
|
|
|
* @return int |
|
313
|
|
|
*/ |
|
314
|
15 |
|
public static function estimateWeight(array $utxos, array $outputs) { |
|
315
|
15 |
|
$outputsSize = SizeEstimation::estimateOutputsSize($outputs); |
|
316
|
15 |
|
$outputsSize += SizeEstimation::getLengthOfVarInt(count($outputs)); |
|
317
|
|
|
|
|
318
|
|
|
$baseSize = 4 + |
|
319
|
15 |
|
SizeEstimation::getLengthOfVarInt(count($utxos)) + SizeEstimation::estimateInputsSize($utxos, false) + |
|
320
|
15 |
|
$outputsSize + 4; |
|
321
|
|
|
|
|
322
|
|
|
$witnessSize = 4 + |
|
323
|
15 |
|
SizeEstimation::getLengthOfVarInt(count($utxos)) + SizeEstimation::estimateInputsSize($utxos, true) + |
|
324
|
15 |
|
$outputsSize + 4; |
|
325
|
|
|
|
|
326
|
15 |
|
return ($baseSize * 3) + $witnessSize; |
|
327
|
|
|
} |
|
328
|
|
|
} |
|
329
|
|
|
|
Sometimes obsolete code just ends up commented out instead of removed. In this case it is better to remove the code once you have checked you do not need it.
The code might also have been commented out for debugging purposes. In this case it is vital that someone uncomments it again or your project may behave in very unexpected ways in production.
This check looks for comments that seem to be mostly valid code and reports them.