add script.isMultisigOut

lib/script.js

@@ -170,15 +170,13 @@ Script.prototype.toString = function() {
   return str.substr(0, str.length - 1);
 };
 
-Script.prototype.isOpReturn = function() {
-  return (this.chunks[0] === Opcode('OP_RETURN').toNumber() &&
-    (this.chunks.length === 1 ||
-      (this.chunks.length === 2 &&
-        this.chunks[1].buf &&
-        this.chunks[1].buf.length <= 40 &&
-        this.chunks[1].length === this.chunks.len)));
-};
 
+
+// script classification methods
+
+/**
+ * @returns true if this is a pay to pubkey hash output script
+ */
 Script.prototype.isPublicKeyHashOut = function() {
   return this.chunks[0] === Opcode('OP_DUP').toNumber() &&
     this.chunks[1] === Opcode('OP_HASH160').toNumber() &&
@@ -187,12 +185,18 @@ Script.prototype.isPublicKeyHashOut = function() {
     this.chunks[4] === Opcode('OP_CHECKSIG').toNumber();
 };
 
+/**
+ * @returns true if this is a pay to public key hash input script
+ */
 Script.prototype.isPublicKeyHashIn = function() {
   return !!(this.chunks.length === 2 &&
     this.chunks[0].buf &&
     this.chunks[1].buf);
 };
 
+/**
+ * @returns true if this is a p2sh output script
+ */
 Script.prototype.isScriptHashOut = function() {
   return this.chunks.length === 3 &&
     this.chunks[0] === Opcode('OP_HASH160').toNumber() &&
@@ -201,13 +205,44 @@ Script.prototype.isScriptHashOut = function() {
     this.chunks[2] === Opcode('OP_EQUAL').toNumber();
 };
 
-//note that these are frequently indistinguishable from pubkeyhashin
+/** 
+ * @returns true if this is a p2sh input script
+ * Note that these are frequently indistinguishable from pubkeyhashin
+ */
 Script.prototype.isScriptHashIn = function() {
   return this.chunks.every(function(chunk) {
     return Buffer.isBuffer(chunk.buf);
   });
 };
 
+/**
+ * @returns true if this is a mutlsig output script
+ */
+Script.prototype.isMultisigOut = function() {
+  return (this.chunks.length > 3 &&
+    Opcode.isSmallIntOp(this.chunks[0]) &&
+    this.chunks.slice(1, this.chunks.length - 2).every(function(obj) {
+      return obj.buf && Buffer.isBuffer(obj.buf);
+    }) &&
+    Opcode.isSmallIntOp(this.chunks[this.chunks.length - 2]) &&
+    this.chunks[this.chunks.length - 1] === Opcode.map.OP_CHECKMULTISIG);
+};
+
+/**
+ * @returns true if this is an OP_RETURN data script
+ */
+Script.prototype.isOpReturn = function() {
+  return (this.chunks[0] === Opcode('OP_RETURN').toNumber() &&
+    (this.chunks.length === 1 ||
+      (this.chunks.length === 2 &&
+        this.chunks[1].buf &&
+        this.chunks[1].buf.length <= 40 &&
+        this.chunks[1].length === this.chunks.len)));
+};
+
+
+// Script construction methods
+
 /**
  * Adds a script element at the start of the script.
  * @param {*} obj a string, number, Opcode, Bufer, or object to add

package.json

@@ -96,8 +96,11 @@
     "mocha": "~2.0.1",
     "run-sequence": "^1.0.2",
     "karma": "^0.12.28",
+    "karma-firefox-launcher": "^0.1.3",
     "karma-mocha": "^0.1.9",
-    "karma-firefox-launcher": "^0.1.3"
+    "lodash": "^2.4.1",
+    "mocha": "~2.0.1",
+    "run-sequence": "^1.0.2"
   },
   "license": "MIT"
 }

test/script.js

@@ -251,6 +251,28 @@ describe('Script', function() {
 
   });
 
+  describe('#isMultisigOut', function() {
+    it('should classify known multisig out 1 as multisig out', function() {
+      Script('OP_2 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 OP_2 OP_CHECKMULTISIG').isMultisigOut().should.equal(true);
+    });
+    it('should classify known multisig out 2 as multisig out', function() {
+      Script('OP_1 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 OP_2 OP_CHECKMULTISIG').isMultisigOut().should.equal(true);
+    });
+    it('should classify known multisig out 3 as multisig out', function() {
+      Script('OP_2 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 21 0x03363d90d447b00c9c99ceac05b6262ee053441c7e55552ffe526bad8f83ff4640 OP_3 OP_CHECKMULTISIG').isMultisigOut().should.equal(true);
+    });
+
+    it('should classify non-multisig out 1 as non-multisig out', function() {
+      Script('OP_2 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 OP_2 OP_CHECKMULTISIG OP_EQUAL').isMultisigOut().should.equal(false);
+    });
+    it('should classify non-multisig out 2 as non-multisig out', function() {
+      Script('OP_2').isMultisigOut().should.equal(false);
+    });
+    it('should classify non-multisig out 3 as non-multisig out', function() {
+      Script('OP_2 OP_2 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 OP_2 OP_CHECKMULTISIG OP_EQUAL').isMultisigOut().should.equal(false);
+    });
+  });
+
   describe('#add and #prepend', function() {
 
     it('should add these ops', function() {