scripts: add allowIncomplete for multisig scripts

src/scripts.js

@@ -1,6 +1,6 @@
 var assert = require('assert')
-var typeForce = require('typeforce')
 var ops = require('./opcodes')
+var typeForce = require('typeforce')
 
 var ecurve = require('ecurve')
 var curve = ecurve.getCurveByName('secp256k1')
@@ -63,7 +63,7 @@ function isPubKeyOutput(script) {
     script.chunks[1] === ops.OP_CHECKSIG
 }
 
-function isScriptHashInput(script) {
+function isScriptHashInput(script, allowIncomplete) {
   if (script.chunks.length < 2) return false
   var lastChunk = script.chunks[script.chunks.length - 1]
 
@@ -72,7 +72,7 @@ function isScriptHashInput(script) {
   var scriptSig = Script.fromChunks(script.chunks.slice(0, -1))
   var scriptPubKey = Script.fromBuffer(lastChunk)
 
-  return classifyInput(scriptSig) === classifyOutput(scriptPubKey)
+  return classifyInput(scriptSig, allowIncomplete) === classifyOutput(scriptPubKey)
 }
 
 function isScriptHashOutput(script) {
@@ -83,9 +83,19 @@ function isScriptHashOutput(script) {
     script.chunks[2] === ops.OP_EQUAL
 }
 
-function isMultisigInput(script) {
-  return script.chunks[0] === ops.OP_0 &&
-    script.chunks.slice(1).every(isCanonicalSignature)
+// allowIncomplete is to account for combining signatures
+// See https://github.com/bitcoin/bitcoin/blob/f425050546644a36b0b8e0eb2f6934a3e0f6f80f/src/script/sign.cpp#L195-L197
+function isMultisigInput(script, allowIncomplete) {
+  if (script.chunks.length < 2) return false
+  if (script.chunks[0] !== ops.OP_0) return false
+
+  if (allowIncomplete) {
+    return script.chunks.slice(1).every(function(chunk) {
+      return chunk === ops.OP_0 || isCanonicalSignature(chunk)
+    })
+  }
+
+  return script.chunks.slice(1).every(isCanonicalSignature)
 }
 
 function isMultisigOutput(script) {
@@ -134,15 +144,15 @@ function classifyOutput(script) {
   return 'nonstandard'
 }
 
-function classifyInput(script) {
+function classifyInput(script, allowIncomplete) {
   typeForce('Script', script)
 
   if (isPubKeyHashInput(script)) {
     return 'pubkeyhash'
-  } else if (isScriptHashInput(script)) {
-    return 'scripthash'
-  } else if (isMultisigInput(script)) {
+  } else if (isMultisigInput(script, allowIncomplete)) {
     return 'multisig'
+  } else if (isScriptHashInput(script, allowIncomplete)) {
+    return 'scripthash'
   } else if (isPubKeyInput(script)) {
     return 'pubkey'
   }
@@ -234,8 +244,13 @@ function multisigInput(signatures, scriptPubKey) {
     var m = mOp - (ops.OP_1 - 1)
     var n = nOp - (ops.OP_1 - 1)
 
-    assert(signatures.length >= m, 'Not enough signatures provided')
-    assert(signatures.length <= n, 'Too many signatures provided')
+    var count = 0
+    signatures.forEach(function(signature) {
+      count += (signature !== ops.OP_0)
+    })
+
+    assert(count >= m, 'Not enough signatures provided')
+    assert(count <= n, 'Too many signatures provided')
   }
 
   return Script.fromChunks([].concat(ops.OP_0, signatures))

src/transaction_builder.js

@@ -1,4 +1,5 @@
 var assert = require('assert')
+var ops = require('./opcodes')
 var scripts = require('./scripts')
 
 var ECPubKey = require('./ecpubkey')
@@ -44,23 +45,23 @@ TransactionBuilder.fromTransaction = function(transaction) {
 
     var redeemScript
     var scriptSig = txIn.script
-    var scriptType = scripts.classifyInput(scriptSig)
+    var scriptType = scripts.classifyInput(scriptSig, true)
 
     // Re-classify if P2SH
     if (scriptType === 'scripthash') {
       redeemScript = Script.fromBuffer(scriptSig.chunks.slice(-1)[0])
       scriptSig = Script.fromChunks(scriptSig.chunks.slice(0, -1))
 
-      scriptType = scripts.classifyInput(scriptSig)
+      scriptType = scripts.classifyInput(scriptSig, true)
       assert.equal(scripts.classifyOutput(redeemScript), scriptType, 'Non-matching scriptSig and scriptPubKey in input')
     }
 
     // Extract hashType, pubKeys and signatures
-    var hashType, pubKeys, signatures
+    var hashType, parsed, pubKeys, signatures
 
     switch (scriptType) {
       case 'pubkeyhash':
-        var parsed = ECSignature.parseScriptSignature(scriptSig.chunks[0])
+        parsed = ECSignature.parseScriptSignature(scriptSig.chunks[0])
         var pubKey = ECPubKey.fromBuffer(scriptSig.chunks[1])
 
         hashType = parsed.hashType
@@ -70,10 +71,9 @@ TransactionBuilder.fromTransaction = function(transaction) {
         break
 
       case 'multisig':
-        var scriptSigs = scriptSig.chunks.slice(1) // ignore OP_0
-        var parsed = scriptSigs.map(function(scriptSig) {
-          return ECSignature.parseScriptSignature(scriptSig)
-        })
+        parsed = scriptSig.chunks.slice(1).filter(function(chunk) {
+          return chunk !== ops.OP_0
+        }).map(ECSignature.parseScriptSignature)
 
         hashType = parsed[0].hashType
         pubKeys = []
@@ -82,7 +82,7 @@ TransactionBuilder.fromTransaction = function(transaction) {
         break
 
       case 'pubkey':
-        var parsed = ECSignature.parseScriptSignature(scriptSig.chunks[0])
+        parsed = ECSignature.parseScriptSignature(scriptSig.chunks[0])
 
         hashType = parsed.hashType
         pubKeys = []

test/fixtures/scripts.json

@@ -53,6 +53,51 @@
       "type": "nulldata",
       "data": "deadffffffffffffffffffffffffffffffffbeef",
       "scriptPubKey": "OP_RETURN deadffffffffffffffffffffffffffffffffbeef"
+    },
+    {
+      "type": "nonstandard",
+      "typeIncomplete": "multisig",
+      "pubKeys": [
+        "0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
+        "02b80011a883a0fd621ad46dfc405df1e74bf075cbaf700fd4aebef6e96f848340",
+        "024289801366bcee6172b771cf5a7f13aaecd237a0b9a1ff9d769cabc2e6b70a34"
+      ],
+      "signatures": [
+        null,
+        "3044022001ab168e80b863fdec694350b587339bb72a37108ac3c989849251444d13ebba02201811272023e3c1038478eb972a82d3ad431bfc2408e88e4da990f1a7ecbb263901",
+        "3045022100aaeb7204c17eee2f2c4ff1c9f8b39b79e75e7fbf33e92cc67ac51be8f15b75f90220659eee314a4943a6384d2b154fa5821ef7a084814d7ee2c6f9f7f0ffb53be34b01"
+      ],
+      "scriptSig": "OP_0 OP_0 3044022001ab168e80b863fdec694350b587339bb72a37108ac3c989849251444d13ebba02201811272023e3c1038478eb972a82d3ad431bfc2408e88e4da990f1a7ecbb263901 3045022100aaeb7204c17eee2f2c4ff1c9f8b39b79e75e7fbf33e92cc67ac51be8f15b75f90220659eee314a4943a6384d2b154fa5821ef7a084814d7ee2c6f9f7f0ffb53be34b01"
+    },
+    {
+      "type": "nonstandard",
+      "typeIncomplete": "multisig",
+      "pubKeys": [
+        "0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
+        "02b80011a883a0fd621ad46dfc405df1e74bf075cbaf700fd4aebef6e96f848340",
+        "024289801366bcee6172b771cf5a7f13aaecd237a0b9a1ff9d769cabc2e6b70a34"
+      ],
+      "signatures": [
+        null,
+        null,
+        null
+      ],
+      "scriptSig": "OP_0 OP_0 OP_0 OP_0"
+    },
+    {
+      "type": "nonstandard",
+      "typeIncomplete": "scripthash",
+      "pubKeys": [
+        "0479be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8",
+        "04c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee51ae168fea63dc339a3c58419466ceaeef7f632653266d0e1236431a950cfe52a"
+      ],
+      "signatures": [
+        null,
+        "30450221009c92c1ae1767ac04e424da7f6db045d979b08cde86b1ddba48621d59a109d818022004f5bb21ad72255177270abaeb2d7940ac18f1e5ca1f53db4f3fd1045647a8a801"
+      ],
+      "redeemScript": "OP_2 0479be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 04c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee51ae168fea63dc339a3c58419466ceaeef7f632653266d0e1236431a950cfe52a OP_2 OP_CHECKMULTISIG",
+      "redeemScriptSig": "OP_0 OP_0 30450221009c92c1ae1767ac04e424da7f6db045d979b08cde86b1ddba48621d59a109d818022004f5bb21ad72255177270abaeb2d7940ac18f1e5ca1f53db4f3fd1045647a8a801",
+      "scriptSig": "OP_0 OP_0 30450221009c92c1ae1767ac04e424da7f6db045d979b08cde86b1ddba48621d59a109d818022004f5bb21ad72255177270abaeb2d7940ac18f1e5ca1f53db4f3fd1045647a8a801 52410479be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b84104c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee51ae168fea63dc339a3c58419466ceaeef7f632653266d0e1236431a950cfe52a52ae"
     }
   ],
   "invalid": {
@@ -121,6 +166,18 @@
       }
     ],
     "multisigInput": [
+      {
+        "description": "Not enough signatures provided",
+        "type": "multisig",
+        "pubKeys": [
+          "0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
+          "02b80011a883a0fd621ad46dfc405df1e74bf075cbaf700fd4aebef6e96f848340"
+        ],
+        "signatures": [
+          null,
+          null
+        ]
+      },
       {
         "exception": "Not enough signatures provided",
         "pubKeys": [

test/scripts.js

@@ -1,4 +1,5 @@
 var assert = require('assert')
+var ops = require('../src/opcodes')
 var scripts = require('../src/scripts')
 
 var ECPubKey = require('../src/ecpubkey')
@@ -22,6 +23,18 @@ describe('Scripts', function() {
         assert.equal(type, f.type)
       })
     })
+
+    fixtures.valid.forEach(function(f) {
+      if (!f.scriptSig) return
+      if (!f.typeIncomplete) return
+
+      it('classifies incomplete ' + f.scriptSig + ' as ' + f.typeIncomplete, function() {
+        var script = Script.fromASM(f.scriptSig)
+        var type = scripts.classifyInput(script, true)
+
+        assert.equal(type, f.typeIncomplete)
+      })
+    })
   })
 
   describe('classifyOutput', function() {
@@ -51,6 +64,16 @@ describe('Scripts', function() {
 
             assert.equal(inputFn(script), expected)
           })
+
+          if (f.typeIncomplete) {
+            var expectedIncomplete = type.toLowerCase() === f.typeIncomplete
+
+            it('returns ' + expected + ' for ' + f.scriptSig, function() {
+              var script = Script.fromASM(f.scriptSig)
+
+              assert.equal(inputFn(script, true), expectedIncomplete)
+            })
+          }
         }
       })
     })
@@ -131,7 +154,7 @@ describe('Scripts', function() {
 
       it('returns ' + f.scriptSig, function() {
         var signatures = f.signatures.map(function(signature) {
-          return new Buffer(signature, 'hex')
+          return signature ? new Buffer(signature, 'hex') : ops.OP_0
         })
 
         var scriptSig = scripts.multisigInput(signatures)
@@ -145,7 +168,7 @@ describe('Scripts', function() {
 
       it('throws on ' + f.exception, function() {
         var signatures = f.signatures.map(function(signature) {
-          return new Buffer(signature, 'hex')
+          return signature ? new Buffer(signature, 'hex') : ops.OP_0
         })
 
         assert.throws(function() {