Address().fromScript(script)

It is convenient to be able to derive an address directly from a script for
p2sh transactions.

lib/address.js

@@ -2,6 +2,7 @@ var base58check = require('./base58check');
 var constants = require('./constants');
 var Hash = require('./hash');
 var Pubkey = require('./pubkey');
+var Script = require('./script');
 
 function Address(obj) {
   if (!(this instanceof Address))
@@ -24,6 +25,13 @@ Address.prototype.fromPubkey = function(pubkey, networkstr) {
   return this;
 };
 
+Address.prototype.fromScript = function(script, networkstr) {
+  this.hashbuf = Hash.sha256ripemd160(script.toBuffer());
+  this.networkstr = networkstr || 'mainnet';
+  this.typestr = 'scripthash';
+  return this;
+};
+
 Address.prototype.fromString = function(str) {
   var buf = base58check.decode(str);
   if (buf.length !== 1 + 20)

test/address.js

@@ -2,6 +2,7 @@ var should = require('chai').should();
 var constants = require('../lib/constants');
 var Pubkey = require('../lib/pubkey');
 var Address = require('../lib/address');
+var Script = require('../lib/script');
 
 describe('Address', function() {
   var pubkeyhash = new Buffer('3c3fa3d4adcaf8f52d5b1843975e122548269937', 'hex');
@@ -45,6 +46,22 @@ describe('Address', function() {
 
   });
 
+  describe('#fromScript', function() {
+
+    it('should make this address from a script', function() {
+      var script = Script().fromString("OP_CHECKMULTISIG");
+      var address = Address().fromScript(script);
+      address.toString().should.equal('3BYmEwgV2vANrmfRymr1mFnHXgLjD6gAWm');
+    });
+
+    it('should make this address from other script', function() {
+      var script = Script().fromString("OP_CHECKSIG OP_HASH160");
+      var address = Address().fromScript(script);
+      address.toString().should.equal('347iRqVwks5r493N1rsLN4k9J7Ljg488W7');
+    });
+
+  });
+
   describe('#fromString', function() {
     
     it('should derive from this known address string mainnet', function() {