Address().fromHashbuf() convenience method

...useful for when you have the pubkeyhash, but not the version byte.

lib/address.js

@@ -51,6 +51,15 @@ Address.prototype.fromBuffer = function(buf) {
   return this;
 };
 
+Address.prototype.fromHashbuf = function(hashbuf, networkstr, typestr) {
+  if (hashbuf.length !== 20)
+    throw new Error('hashbuf must be exactly 20 bytes');
+  this.hashbuf = hashbuf;
+  this.networkstr = networkstr || 'mainnet';
+  this.typestr = typestr || 'pubkeyhash';
+  return this;
+};
+
 Address.prototype.fromPubkey = function(pubkey, networkstr) {
   this.hashbuf = Hash.sha256ripemd160(pubkey.toBuffer());
   this.networkstr = networkstr || 'mainnet';

test/address.js

@@ -38,6 +38,23 @@ describe('Address', function() {
 
   });
 
+  describe('#fromHashbuf', function() {
+    
+    it('should make an address from a hashbuf', function() {
+      Address().fromHashbuf(pubkeyhash).toString().should.equal(str);
+      var a = Address().fromHashbuf(pubkeyhash, 'testnet', 'scripthash');
+      a.networkstr.should.equal('testnet');
+      a.typestr.should.equal('scripthash');
+    });
+
+    it('should throw an error for invalid length hashbuf', function() {
+      (function() {
+        Address().fromHashbuf(buf);
+      }).should.throw('hashbuf must be exactly 20 bytes');
+    });
+
+  });
+
   describe('#fromPubkey', function() {
 
     it('should make this address from a compressed pubkey', function() {