Speculatively implement P2S, OP_EVAL, and OP_POW (#150)

Author: bitjson

.changeset/tall-actors-sell.md

@@ -0,0 +1,5 @@
+---
+'@bitauth/libauth': minor
+---
+
+Speculatively implement P2S, OP_EVAL, and OP_POW

src/lib/engine/types/template-types.ts

@@ -841,6 +841,8 @@ export type WalletTemplateScriptLocking = WalletTemplateScript & {
    * The presence of the `lockingType` property indicates that this script is a
    * locking script. It must be present on any script referenced by the
    * `unlocks` property of another script.
+   * 
+   * TODO: migrate `standard` -> `p2s`
    */
   lockingType: 'p2sh20' | 'p2sh32' | 'standard';
 };

src/lib/language/language-utils.ts

@@ -651,7 +651,8 @@ export const extractEvaluationSamples = <
  * outer evaluation appear before their parent sample (which uses their result).
  */
 export const extractEvaluationSamplesRecursive = <
-  ProgramState extends AuthenticationProgramStateMinimum,
+  ProgramState extends AuthenticationProgramStateControlStack &
+    AuthenticationProgramStateMinimum,
 >({
   /**
    * The range of the script node that was evaluated to produce the `trace`
@@ -670,6 +671,8 @@ export const extractEvaluationSamplesRecursive = <
   nodes: ScriptReductionTraceScriptNode<ProgramState>['script'];
   trace: ProgramState[];
 }): SampleExtractionResult<ProgramState> => {
+  const statesNotProducedByOpEval = (state: ProgramState) =>
+    !state.controlStack.some((item) => typeof item === 'object');
   const extractEvaluations = (
     node: ScriptReductionTraceChildNode<ProgramState>,
     depth = 1,
@@ -690,7 +693,9 @@ export const extractEvaluationSamplesRecursive = <
         ],
         [],
       );
-      const traceWithoutUnlockingPhase = node.trace.slice(1);
+      const traceWithoutUnlockingPhase = node.trace
+        .slice(1)
+        .filter(statesNotProducedByOpEval);
       const evaluationBeginToken = '$(';
       const evaluationEndToken = ')';
       const extracted = extractEvaluationSamples<ProgramState>({
@@ -711,7 +716,7 @@ export const extractEvaluationSamplesRecursive = <
   const { samples, unmatchedStates } = extractEvaluationSamples<ProgramState>({
     evaluationRange,
     nodes,
-    trace,
+    trace: trace.filter(statesNotProducedByOpEval),
   });
 
   const childSamples = nodes.reduce<EvaluationSample<ProgramState>[]>(
@@ -825,6 +830,7 @@ export const extractUnexecutedRanges = <
   return containedRangesExcluded;
 };
 
+const oneBelowHash160 = 19;
 /**
  * Given a stack, return a summary of the stack's contents, encoding valid VM
  * numbers as numbers, and all other stack items as hex literals.
@@ -833,7 +839,9 @@ export const extractUnexecutedRanges = <
  */
 export const summarizeStack = (stack: Uint8Array[]) =>
   stack.map((item) => {
-    const asNumber = vmNumberToBigInt(item);
+    const asNumber = vmNumberToBigInt(item, {
+      maximumVmNumberByteLength: oneBelowHash160,
+    });
     return `0x${binToHex(item)}${
       typeof asNumber === 'string' ? '' : `(${asNumber.toString()})`
     }`;
@@ -879,8 +887,7 @@ export const summarizeDebugTrace = <
               ...(nextState.error === undefined
                 ? {}
                 : { error: nextState.error }),
-              execute:
-                state.controlStack[state.controlStack.length - 1] !== false,
+              execute: state.controlStack.every((item) => item !== false),
               instruction:
                 'instruction' in state
                   ? state.instruction

src/lib/vm/instruction-sets/bch/2023/bch-2023-consensus.ts

@@ -17,7 +17,6 @@ export const ConsensusBch2023 = {
    * A.K.A. `MAX_SCRIPT_SIZE`
    */
   maximumBytecodeLength: 10000,
-  maximumCommitmentLength: 40,
   /**
    * A.K.A. `MAX_CONSENSUS_VERSION`
    */
@@ -40,6 +39,10 @@ export const ConsensusBch2023 = {
    * A.K.A. `MAX_SCRIPT_ELEMENT_SIZE`
    */
   maximumStackItemLength: 520,
+  /**
+   * When set to `-1`, only BCH_2023_05 standard patterns are accepted.
+   */
+  maximumStandardLockingBytecodeLength: -1,
   /**
    * A.K.A. `MAX_STANDARD_TX_SIZE`
    */
@@ -48,6 +51,7 @@ export const ConsensusBch2023 = {
    * A.K.A. `MAX_TX_IN_SCRIPT_SIG_SIZE`
    */
   maximumStandardUnlockingBytecodeLength: 1650,
+  maximumTokenCommitmentLength: 40,
   /**
    * A.K.A. `MAX_TX_SIZE`
    */

src/lib/vm/instruction-sets/bch/2023/bch-2023-instruction-set.ts

@@ -911,10 +911,20 @@ export const createInstructionSetBch2023 = <
 
         // eslint-disable-next-line functional/no-loop-statements
         for (const [index, output] of sourceOutputs.entries()) {
-          if (!isStandardUtxoBytecode(output.lockingBytecode)) {
+          if (consensus.maximumStandardLockingBytecodeLength === -1) {
+            if (!isStandardUtxoBytecode(output.lockingBytecode)) {
+              return formatError(
+                AuthenticationErrorCommon.verifyStandardFailedNonstandardSourceOutput,
+                `Source output ${index} is non-standard: locking bytecode does not match a standard pattern: P2PKH, P2PK, P2SH, P2MS, or arbitrary data (OP_RETURN).`,
+              );
+            }
+          } else if (
+            output.lockingBytecode.length >
+            consensus.maximumStandardLockingBytecodeLength
+          ) {
             return formatError(
               AuthenticationErrorCommon.verifyStandardFailedNonstandardSourceOutput,
-              `Source output ${index} is non-standard: locking bytecode does not match a standard pattern: P2PKH, P2PK, P2SH, P2MS, or arbitrary data (OP_RETURN).`,
+              `Source output ${index} is non-standard: locking bytecode length of ${output.lockingBytecode.length} exceeds the maximum standard locking bytecode length of ${consensus.maximumStandardLockingBytecodeLength}.`,
             );
           }
         }
@@ -923,21 +933,32 @@ export const createInstructionSetBch2023 = <
         let totalArbitraryDataBytes = 0;
         // eslint-disable-next-line functional/no-loop-statements
         for (const [index, output] of transaction.outputs.entries()) {
-          if (!isStandardOutputBytecode(output.lockingBytecode)) {
-            return formatError(
-              AuthenticationErrorCommon.verifyStandardFailedNonstandardOutput,
-              `Transaction output ${index} is non-standard: locking bytecode does not match a standard pattern: P2PKH, P2PK, P2SH, P2MS, or arbitrary data (OP_RETURN).`,
-            );
-          }
-          // eslint-disable-next-line functional/no-conditional-statements
-          if (isArbitraryDataOutput(output.lockingBytecode)) {
-            // eslint-disable-next-line functional/no-expression-statements
-            totalArbitraryDataBytes += output.lockingBytecode.length + 1;
+          if (consensus.maximumStandardLockingBytecodeLength === -1) {
+            if (!isStandardOutputBytecode(output.lockingBytecode)) {
+              return formatError(
+                AuthenticationErrorCommon.verifyStandardFailedNonstandardOutput,
+                `Transaction output ${index} is non-standard: locking bytecode does not match a standard pattern: P2PKH, P2PK, P2SH, P2MS, or arbitrary data (OP_RETURN).`,
+              );
+            }
+          } else if (
+            output.lockingBytecode.length >
+            consensus.maximumStandardLockingBytecodeLength
+          ) {
+            // eslint-disable-next-line functional/no-conditional-statements
+            if (isArbitraryDataOutput(output.lockingBytecode)) {
+              // eslint-disable-next-line functional/no-expression-statements
+              totalArbitraryDataBytes += output.lockingBytecode.length + 1;
+            } else {
+              return formatError(
+                AuthenticationErrorCommon.verifyStandardFailedNonstandardOutput,
+                `Transaction output ${index} is non-standard: locking bytecode length of ${output.lockingBytecode.length} exceeds the maximum standard locking bytecode length of ${consensus.maximumStandardLockingBytecodeLength} and does not match the standard arbitrary data pattern (OP_RETURN).`,
+              );
+            }
           }
           if (isDustOutput(output)) {
             return formatError(
               AuthenticationErrorCommon.verifyStandardFailedDustOutput,
-              ` Transaction output ${index} must have a value of at least ${getDustThreshold(
+              `Transaction output ${index} must have a value of at least ${getDustThreshold(
                 output,
               )} satoshis. Current value: ${output.valueSatoshis}`,
             );
@@ -973,6 +994,9 @@ export const createInstructionSetBch2023 = <
       const tokenValidationResult = verifyTransactionTokens(
         transaction,
         sourceOutputs,
+        {
+          maximumTokenCommitmentLength: consensus.maximumTokenCommitmentLength,
+        },
       );
       if (tokenValidationResult !== true) {
         return tokenValidationResult;

src/lib/vm/instruction-sets/bch/2023/bch-2023-tokens.ts

@@ -177,19 +177,17 @@ export const extractTransactionOutputTokenData = (
 export const verifyTransactionTokens = (
   transaction: Transaction,
   sourceOutputs: Output[],
+  { maximumTokenCommitmentLength }: { maximumTokenCommitmentLength: number },
 ) => {
   const excessiveCommitment = [...sourceOutputs, ...transaction.outputs].find(
     (output) =>
       output.token?.nft?.commitment !== undefined &&
-      output.token.nft.commitment.length >
-        ConsensusBch2023.maximumCommitmentLength,
+      output.token.nft.commitment.length > maximumTokenCommitmentLength,
   );
   if (excessiveCommitment !== undefined) {
     return formatError(
       AuthenticationErrorCommon.tokenValidationExcessiveCommitmentLength,
-      `A token commitment exceeds the consensus limit of ${
-        ConsensusBch2023.maximumCommitmentLength
-      } bytes. Excessive token commitment length: ${
+      `A token commitment exceeds the consensus limit of ${maximumTokenCommitmentLength} bytes. Excessive token commitment length: ${
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
         excessiveCommitment.token!.nft!.commitment.length
       }`,

src/lib/vm/instruction-sets/bch/2026/bch-2026-consensus.ts

@@ -4,7 +4,10 @@ import { ConsensusBch2025 } from '../2025/bch-2025-consensus.js';
  * Consensus setting overrides for the `BCH_SPEC` instruction set.
  */
 // eslint-disable-next-line @typescript-eslint/naming-convention
-export const ConsensusBch2026Overrides = {};
+export const ConsensusBch2026Overrides = {
+  maximumStandardLockingBytecodeLength: 201,
+  maximumTokenCommitmentLength: 80,
+};
 
 /**
  * Consensus settings for the `BCH_SPEC` instruction set.

src/lib/vm/instruction-sets/bch/2026/bch-2026-descriptions.ts

@@ -0,0 +1,20 @@
+import { OpcodeDescriptionsBch2023 } from '../2023/bch-2023-descriptions.js';
+
+/**
+ * Descriptions for the opcodes added to the `BCH_2026_05` instruction set
+ * beyond those present in `BCH_2025_05`.
+ */
+export enum OpcodeDescriptionsBch2026Additions {
+  OP_EVAL = 'Pop the top item from the stack as bytecode. Preserve the active bytecode at the top of the control stack, then evaluate the bytecode as if it were the active bytecode (without modifying the stack, alternate stack, or other evaluation context). When the evaluation is complete, restore the original bytecode and continue evaluation after the OP_EVAL instruction. If the bytecode is malformed, error.',
+  OP_BEGIN = 'Push the current instruction pointer index to the control stack as an integer (to be read by OP_UNTIL).',
+  OP_UNTIL = 'Pop the top item from the control stack (if the control value is not an integer, error). Add the difference between the control value and the current instruction pointer index to the repeated bytes counter, if the sum of the repeated bytes counter and the active bytecode length is greater than the maximum bytecode length, error. Pop the top item from the stack, if the value is not truthy, move the instruction pointer to the control value (and re-evaluate the OP_BEGIN).',
+}
+
+/**
+ * Descriptions for the `BCH_SPEC` instruction set.
+ */
+// eslint-disable-next-line @typescript-eslint/naming-convention
+export const OpcodeDescriptionsBch2026 = {
+  ...OpcodeDescriptionsBch2023,
+  ...OpcodeDescriptionsBch2026Additions,
+};

src/lib/vm/instruction-sets/bch/2026/bch-2026-errors.ts

@@ -4,6 +4,7 @@ export enum AuthenticationErrorBch2026Additions {
   unexpectedUntil = 'Encountered an OP_UNTIL that is not following a matching OP_BEGIN.',
   unexpectedUntilMissingEndIf = 'Encountered an OP_UNTIL before the previous OP_IF was closed by an OP_ENDIF.',
   excessiveLooping = 'Program attempted an OP_UNTIL operation that would exceed the limit of repeated bytes.',
+  malformedEval = 'Program attempted to OP_EVAL malformed bytecode.',
 }
 
 /**

src/lib/vm/instruction-sets/bch/2026/bch-2026-eval.ts

@@ -0,0 +1,49 @@
+import type {
+  AuthenticationInstructionMalformed,
+  AuthenticationProgramStateBch2026,
+} from '../../../../lib.js';
+import {
+  applyError,
+  authenticationInstructionsAreMalformed,
+  decodeAuthenticationInstructions,
+  disassembleAuthenticationInstructionMalformed,
+  executionIsActive,
+  pushToControlStack,
+  useOneStackItem,
+} from '../../common/common.js';
+
+import { AuthenticationErrorBch2026 } from './bch-2026-errors.js';
+import { OpcodesBch2026 } from './bch-2026-opcodes.js';
+
+export const opEval = <State extends AuthenticationProgramStateBch2026>(
+  state: State,
+) => {
+  if (executionIsActive(state)) {
+    return useOneStackItem(state, (nextState, [item]) => {
+      const newInstructions = decodeAuthenticationInstructions(item);
+
+      if (authenticationInstructionsAreMalformed(newInstructions)) {
+        return applyError(
+          nextState,
+          AuthenticationErrorBch2026.malformedEval,
+          `Malformed instruction: ${disassembleAuthenticationInstructionMalformed(
+            OpcodesBch2026,
+            newInstructions[
+              newInstructions.length - 1
+            ] as AuthenticationInstructionMalformed,
+          )}.`,
+        );
+      }
+
+      const manuallyAdvance = 1;
+      const finalState = pushToControlStack(nextState, {
+        instructions: nextState.instructions,
+        ip: nextState.ip + manuallyAdvance,
+      });
+      finalState.ip = 0 - manuallyAdvance; // eslint-disable-line functional/no-expression-statements, functional/immutable-data
+      finalState.instructions = newInstructions; // eslint-disable-line functional/no-expression-statements, functional/immutable-data
+      return finalState;
+    });
+  }
+  return state;
+};