Add support for verifying segwit scripts

lib/script/interpreter.js

@@ -31,6 +31,70 @@ var Interpreter = function Interpreter(obj) {
   }
 };
 
+Interpreter.prototype.verifyWitnessProgram = function(version, program, witness, satoshis, flags) {
+  var scriptPubKey = new Script;
+  var stack = [];
+
+  if (version == 0) {
+    if (program.length == 32) {
+      if (witness.length == 0) {
+        this.errstr = 'v0 scripthash program empty';
+        return false;
+      }
+
+      scriptPubKey = witness[witness.length - 1];
+      var hash = Hash.sha256(scriptPubKey);
+      if (hash !== program.script) {
+        this.errstr = 'witness program mismatch';
+        return false;
+      }
+
+      stack = witness.slice(0, -1);
+    } else if (program.script.length == 20) {
+      if (witness.length != 2) {
+        this.errstr = 'witness program mismatch';
+        return false;
+      }
+
+      scriptPubKey.add(Opcode.OP_DUP).add(Opcode.OP_HASH160).add(program.script).add(Opcode.OP_EQUALVERIFY).add(Opcode.OP_CHECKSIG);
+      stack = witness;
+    } else {
+      this.errstr = 'Witness program wrong length';
+      return false;
+    }
+  } else if ((flags & this.SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM)) {
+    this.errstr = 'Upgradeable witness program discouraged';
+    return false;
+  } else {
+    return true;
+  }
+
+  this.set({
+    script: scriptPubKey,
+    stack: stack,
+    sigversion: 1,
+    satoshis: satoshis
+  });
+
+  if (!this.evaluate()) {
+    return false;
+  }
+
+  if (this.stack.length !== 1) {
+    this.errstr = 'SCRIPT_ERR_EVAL_FALSE';
+    return false;
+  }
+  var buf = this.stack[this.stack.length - 1];
+  if (!Interpreter.castToBool(buf)) {
+    this.errstr = 'SCRIPT_ERR_EVAL_FALSE_IN_STACK';
+    return false;
+  }
+
+  return true;
+};
+
+
+
 /**
  * Verifies a Script by executing it and returns true if it is valid.
  * This function needs to be provided with the scriptSig and the scriptPubkey
@@ -41,10 +105,13 @@ var Interpreter = function Interpreter(obj) {
  *    to check signature validity for some opcodes like OP_CHECKSIG)
  * @param {number} nin - index of the transaction input containing the scriptSig verified.
  * @param {number} flags - evaluation flags. See Interpreter.SCRIPT_* constants
+ * @param {number} witness - array of witness data
+ * @param {number} satoshis - number of satoshis created by this output
  *
  * Translated from bitcoind's VerifyScript
  */
-Interpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin, flags) {
+  Interpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin, flags, witness, satoshis) {
+
   var Transaction = require('../transaction');
   if (_.isUndefined(tx)) {
     tx = new Transaction();
@@ -55,10 +122,19 @@ Interpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin, flags)
   if (_.isUndefined(flags)) {
     flags = 0;
   }
+  if (_.isUndefined(witness)) {
+    witness = null;
+  }
+  if (_.isUndefined(satoshis)) {
+    satoshis = 0;
+  }
+
   this.set({
     script: scriptSig,
     tx: tx,
     nin: nin,
+    sigversion: 0,
+    satoshis: 0,
     flags: flags
   });
   var stackCopy;
@@ -103,6 +179,24 @@ Interpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin, flags)
     return false;
   }
 
+  var hadWitness = false;
+  var version, program;
+
+  if ((flags & Interpreter.SCRIPT_VERIFY_WITNESS)) {
+    if (scriptPubkey.isWitnessProgram()) {
+      version = scriptPubkey[0];
+      program = s.toProgram();
+      hadWitness = true;
+      if (scriptSig.toBuffer().length != 0) {
+        return false;
+      }
+
+      if (!this.verifyWitnessProgram(version, program, witness, satoshis, flags)) {
+        return false;
+      }
+    }
+  }
+
   // Additional validation for spend-to-script-hash transactions:
   if ((flags & Interpreter.SCRIPT_VERIFY_P2SH) && scriptPubkey.isScriptHashOut()) {
     // scriptSig must be literals-only or validation fails
@@ -144,8 +238,30 @@ Interpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin, flags)
     if (!Interpreter.castToBool(stackCopy[stackCopy.length - 1])) {
       this.errstr = 'SCRIPT_ERR_EVAL_FALSE_IN_P2SH_STACK';
       return false;
-    } else {
-      return true;
+    }
+    if ((flags & this.SCRIPT_VERIFY_WITNESS)) {
+      if (redeemScript.isWitnessOut()) {
+        version = redeemScript[0];
+        program = redeemScript.toProgram();
+        hadWitness = true;
+        if (scriptSig !== redeemScript) {
+          this.errstr = 'Malleated scriptSig';
+          return false;
+        }
+
+        if (!this.verifyWitnessProgram(version, program, witness, satoshis, flags)) {
+          return false;
+        }
+
+        stack = [stack[0]];
+      }
+    }
+
+    if ((flags & this.SCRIPT_VERIFY_WITNESS)) {
+      if (!hadWitness && witness.length > 0) {
+        this.errstr = 'Witness unexpected';
+        return false;
+      }
     }
   }
 
@@ -158,6 +274,8 @@ Interpreter.prototype.initialize = function(obj) {
   this.stack = [];
   this.altstack = [];
   this.pc = 0;
+  this.satoshis = 0;
+  this.sigversion = 0;
   this.pbegincodehash = 0;
   this.nOpCount = 0;
   this.vfExec = [];
@@ -173,6 +291,8 @@ Interpreter.prototype.set = function(obj) {
   this.altstack = obj.altack || this.altstack;
   this.pc = typeof obj.pc !== 'undefined' ? obj.pc : this.pc;
   this.pbegincodehash = typeof obj.pbegincodehash !== 'undefined' ? obj.pbegincodehash : this.pbegincodehash;
+  this.sigversion = typeof obj.sigversion !== 'undefined' ? obj.sigversion : this.sigversion;
+  this.satoshis = typeof obj.satoshis !== 'undefined' ? obj.satoshis : this.satoshis;
   this.nOpCount = typeof obj.nOpCount !== 'undefined' ? obj.nOpCount : this.nOpCount;
   this.vfExec = obj.vfExec || this.vfExec;
   this.errstr = obj.errstr || this.errstr;
@@ -231,6 +351,8 @@ Interpreter.SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1 << 7);
 
 // CLTV See BIP65 for details.
 Interpreter.SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY = (1 << 9);
+Interpreter.SCRIPT_VERIFY_WITNESS = (1 << 10);
+Interpreter.SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1 << 11);
 
 Interpreter.castToBool = function(buf) {
   for (var i = 0; i < buf.length; i++) {
@@ -1111,7 +1233,7 @@ Interpreter.prototype.step = function() {
           try {
             sig = Signature.fromTxFormat(bufSig);
             pubkey = PublicKey.fromBuffer(bufPubkey, false);
-            fSuccess = this.tx.verifySignature(sig, pubkey, this.nin, subscript);
+            fSuccess = this.tx.verifySignature(sig, pubkey, this.nin, subscript, this.sigversion);
           } catch (e) {
             //invalid sig or pubkey
             fSuccess = false;
@@ -1200,7 +1322,7 @@ Interpreter.prototype.step = function() {
             try {
               sig = Signature.fromTxFormat(bufSig);
               pubkey = PublicKey.fromBuffer(bufPubkey, false);
-              fOk = this.tx.verifySignature(sig, pubkey, this.nin, subscript);
+              fOk = this.tx.verifySignature(sig, pubkey, this.nin, subscript, this.sigversion);
             } catch (e) {
               //invalid sig or pubkey
               fOk = false;