Completed
Pull Request — master (#118)
by thomas
02:37
created

SizeEstimation::estimateInputsSize()   A

Complexity

Conditions 5
Paths 6

Size

Total Lines 19

Duplication

Lines 0
Ratio 0 %

Code Coverage

Tests 0
CRAP Score 30

Importance

Changes 0
Metric Value
cc 5
nc 6
nop 2
dl 0
loc 19
ccs 0
cts 13
cp 0
crap 30
rs 9.3222
c 0
b 0
f 0
1
<?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 ($length <= 0xffff) {
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            return 3;
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        } else if ($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 $length
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     * @return int
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     */
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    public static function getLengthOfVarInt($length) {
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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
0 ignored issues
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Unused Code Comprehensibility introduced by
38% of this comment could be valid code. Did you maybe forget this after debugging?

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.

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104
        $scriptSize += 1; // OP_CHECKSIG
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        return [$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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        if ($decodePK->getType() === ScriptType::P2WKH) {
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            $scriptSitu = ScriptFactory::scriptPubKey()->p2pkh($decodePK->getSolution());
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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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        $script = $decodePK->getScript();
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        list ($scriptSig, $witness) = SizeEstimation::estimateInputFromScripts($script, $redeemScript, $witnessScript, $witness);
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        return [
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            "scriptSig" => $scriptSig,
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            "witness" => $witness,
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        ];
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    }
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    /**
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     * @param UTXO[] $utxos
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     * @param bool $withWitness
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     * @return integer
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     */
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    public static function estimateInputsSize(array $utxos, $withWitness) {
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        $inputSize = 0;
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        $witnessSize = 0;
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        foreach ($utxos as $utxo) {
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            $estimate = SizeEstimation::estimateUtxo($utxo);
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            $inputSize += 32 + 4 + 4;
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            $inputSize += $estimate['scriptSig'];
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            if ($withWitness) {
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                $witnessSize += $estimate['witness'];
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            }
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        }
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        if ($withWitness && $witnessSize != 0) {
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            $inputSize += $witnessSize;
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            $inputSize += 2; // flag bytes
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        }
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        return $inputSize;
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    }
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    /**
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     * @param array $outputs
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     * @return int
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     */
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    public static function estimateOutputsSize(array $outputs) {
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        $outputSize = 0;
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        foreach ($outputs as $output) {
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            $size = 8;
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            $scriptSize = null;
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Unused Code introduced by
$scriptSize is not used, you could remove the assignment.

This check looks for variable assignements that are either overwritten by other assignments or where the variable is not used subsequently.

$myVar = 'Value';
$higher = false;

if (rand(1, 6) > 3) {
    $higher = true;
} else {
    $higher = false;
}

Both the $myVar assignment in line 1 and the $higher assignment in line 2 are dead. The first because $myVar is never used and the second because $higher is always overwritten for every possible time line.

Loading history...
280
            if ($output instanceof TransactionOutputInterface) {
281
                $scriptSize = $output->getScript()->getBuffer()->getSize();
282
            } else {
283
                if (isset($output['scriptPubKey'])) {
284
                    if ($output['scriptPubKey'] instanceof ScriptInterface) {
285
                        $scriptSize = $output['scriptPubKey']->getBuffer()->getSize();
286
                    } else {
287
                        $scriptSize = strlen($output['scriptPubKey']) / 2;
288
                    }
289
                } else {
290
                    $scriptSize = 25;
291
                }
292
            }
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            $size += SizeEstimation::getLengthOfVarInt($scriptSize) + $scriptSize;
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            $outputSize += $size;
296
        }
297
        return $outputSize;
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    }
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    /**
301
     * @param UTXO[] $utxos
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     * @param array $outputs
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     * @return int
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     */
305
    public static function estimateVsize(array $utxos, array $outputs) {
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        return (int)ceil(self::estimateWeight($utxos, $outputs) / 4);
307
    }
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    /**
310
     * @param UTXO[] $utxos
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     * @param array $outputs
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     * @return int
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     */
314
    public static function estimateWeight(array $utxos, array $outputs) {
315
        $outputsSize = SizeEstimation::estimateOutputsSize($outputs);
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        $outputsSize += SizeEstimation::getLengthOfVarInt(count($outputs));
317
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        $baseSize = 4 +
319
            SizeEstimation::getLengthOfVarInt(count($utxos)) + SizeEstimation::estimateInputsSize($utxos, false) +
320
            $outputsSize + 4;
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        $witnessSize = 4 +
323
            SizeEstimation::getLengthOfVarInt(count($utxos)) + SizeEstimation::estimateInputsSize($utxos, true) +
324
            $outputsSize + 4;
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        return ($baseSize * 3) + $witnessSize;
327
    }
328
}
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