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<?php |
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declare(strict_types=1); |
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namespace BitWasp\Bitcoin\Script\Path; |
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use BitWasp\Bitcoin\Script\Interpreter\Stack; |
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use BitWasp\Bitcoin\Script\Opcodes; |
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use BitWasp\Bitcoin\Script\ScriptInterface; |
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class BranchInterpreter |
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{ |
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/** |
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* @var array |
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*/ |
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private $disabledOps = [ |
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Opcodes::OP_CAT, Opcodes::OP_SUBSTR, Opcodes::OP_LEFT, Opcodes::OP_RIGHT, |
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Opcodes::OP_INVERT, Opcodes::OP_AND, Opcodes::OP_OR, Opcodes::OP_XOR, |
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Opcodes::OP_2MUL, Opcodes::OP_2DIV, Opcodes::OP_MUL, Opcodes::OP_DIV, |
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Opcodes::OP_MOD, Opcodes::OP_LSHIFT, Opcodes::OP_RSHIFT |
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]; |
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/** |
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* @param ScriptInterface $script |
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* @return ParsedScript |
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*/ |
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public function getScriptTree(ScriptInterface $script): ParsedScript |
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{ |
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$ast = $this->getAstForLogicalOps($script); |
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$scriptPaths = $ast->flags(); |
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136 |
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$scriptBranches = []; |
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136 |
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if (count($scriptPaths) > 1) { |
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foreach ($scriptPaths as $path) { |
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$scriptBranches[] = $this->getBranchForPath($script, $path); |
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} |
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} else { |
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$scriptBranches[] = $this->getBranchForPath($script, []); |
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} |
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return new ParsedScript($script, $ast, $scriptBranches); |
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} |
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/** |
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* Build tree of dependent logical ops |
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* @param ScriptInterface $script |
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* @return LogicOpNode |
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*/ |
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public function getAstForLogicalOps(ScriptInterface $script): LogicOpNode |
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{ |
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$root = new LogicOpNode(null); |
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$current = $root; |
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foreach ($script->getScriptParser()->decode() as $op) { |
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switch ($op->getOp()) { |
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case Opcodes::OP_IF: |
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case Opcodes::OP_NOTIF: |
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$split = $current->split(); |
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$current = $split[$op->getOp() & 1]; |
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break; |
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case Opcodes::OP_ENDIF: |
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if (null === $current->getParent()) { |
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throw new \RuntimeException("Unexpected ENDIF, current scope had no parent"); |
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} |
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$current = $current->getParent(); |
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break; |
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case Opcodes::OP_ELSE: |
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if (null === $current->getParent()) { |
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throw new \RuntimeException("Unexpected ELSE, current scope had no parent"); |
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} |
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$current = $current->getParent()->getChild((int) !$current->getValue()); |
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break; |
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} |
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} |
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if (!$current->isRoot()) { |
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throw new \RuntimeException("Unbalanced conditional - vfStack not empty at script termination"); |
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} |
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return $root; |
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} |
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/** |
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* Given a script and path, attempt to produce a ScriptBranch instance |
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* |
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* @param ScriptInterface $script |
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* @param bool[] $path |
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* @return ScriptBranch |
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*/ |
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public function getBranchForPath(ScriptInterface $script, array $path): ScriptBranch |
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{ |
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// parses the opcodes which were actually run |
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$segments = $this->evaluateUsingStack($script, $path); |
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return new ScriptBranch($script, $path, $segments); |
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} |
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/** |
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* @param Stack $vfStack |
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* @param bool $value |
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* @return bool |
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*/ |
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private function checkExec(Stack $vfStack, bool $value): bool |
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{ |
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$ret = 0; |
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foreach ($vfStack as $item) { |
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if ($item === $value) { |
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$ret++; |
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} |
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} |
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return (bool) $ret; |
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} |
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/** |
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* @param ScriptInterface $script |
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* @param int[] $logicalPath |
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* @return array - array of Operation[] representing script segments |
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*/ |
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public function evaluateUsingStack(ScriptInterface $script, array $logicalPath): array |
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{ |
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$mainStack = new Stack(); |
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foreach (array_reverse($logicalPath) as $setting) { |
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$mainStack->push($setting); |
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} |
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$vfStack = new Stack(); |
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$parser = $script->getScriptParser(); |
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$tracer = new PathTracer(); |
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foreach ($parser as $i => $operation) { |
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$opCode = $operation->getOp(); |
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$fExec = !$this->checkExec($vfStack, false); |
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if (in_array($opCode, $this->disabledOps, true)) { |
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throw new \RuntimeException('Disabled Opcode'); |
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} |
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if (Opcodes::OP_IF <= $opCode && $opCode <= Opcodes::OP_ENDIF) { |
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switch ($opCode) { |
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case Opcodes::OP_IF: |
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case Opcodes::OP_NOTIF: |
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// <expression> if [statements] [else [statements]] endif |
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$value = false; |
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if ($fExec) { |
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if ($mainStack->isEmpty()) { |
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$op = $script->getOpcodes()->getOp($opCode & 1 ? Opcodes::OP_IF : Opcodes::OP_NOTIF); |
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throw new \RuntimeException("Unbalanced conditional at {$op} - not included in logicalPath"); |
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} |
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$value = $mainStack->pop(); |
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if ($opCode === Opcodes::OP_NOTIF) { |
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$value = !$value; |
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} |
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} |
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$vfStack->push($value); |
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break; |
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case Opcodes::OP_ELSE: |
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if ($vfStack->isEmpty()) { |
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throw new \RuntimeException('Unbalanced conditional at OP_ELSE'); |
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} |
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$vfStack->push(!$vfStack->pop()); |
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break; |
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case Opcodes::OP_ENDIF: |
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if ($vfStack->isEmpty()) { |
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1 |
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throw new \RuntimeException('Unbalanced conditional at OP_ENDIF'); |
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} |
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$vfStack->pop(); |
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break; |
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} |
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$tracer->operation($operation); |
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} else if ($fExec) { |
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// Fill up trace with executed opcodes |
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$tracer->operation($operation); |
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} |
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} |
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if (count($vfStack) !== 0) { |
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1 |
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throw new \RuntimeException('Unbalanced conditional at script end'); |
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} |
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if (count($mainStack) !== 0) { |
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1 |
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throw new \RuntimeException('Values remaining after script execution - invalid branch data'); |
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} |
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return $tracer->done(); |
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} |
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} |
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Bit-Wasp /
bitcoin-php
