Address: add Address.*ScriptPubKey and tests

The introduction of these two functions allow for the all the network
related code to be eventually removed from Transaction and Script.

Previously the result for non-standard transactions was undefined
behaviour.  This change mandates that an exception is thrown if a
non-standard transaction is input.

src/address.js

@@ -1,5 +1,22 @@
 var assert = require('assert')
 var base58check = require('./base58check')
+var networks = require('./networks')
+
+function findScriptTypeByVersion(queryVersion) {
+  for (var networkName in networks) {
+    var network = networks[networkName]
+
+    for (var versionName in network) {
+      var version = network[versionName]
+
+      if (version === queryVersion) {
+        return versionName
+      }
+    }
+  }
+
+  throw new Error('Version has no corresponding network')
+}
 
 function Address(hash, version) {
   assert(Buffer.isBuffer(hash), 'First argument must be a Buffer')
@@ -17,10 +34,48 @@ Address.fromBase58Check = function(string) {
   return new Address(decode.payload, decode.version)
 }
 
+Address.fromScriptPubKey = function(script, network) {
+  network = network || networks.bitcoin
+
+  var type = script.getOutType()
+
+  // Pay-to-pubKeyHash
+  if (type === 'pubkeyhash') {
+    return new Address(new Buffer(script.chunks[2]), network.pubKeyHash)
+  }
+
+  // Pay-to-scriptHash
+  else if (type === 'scripthash') {
+    return new Address(new Buffer(script.chunks[1]), network.scriptHash)
+  }
+
+  throw new Error('Could not derive address from script')
+}
+
 // Export functions
 Address.prototype.toBase58Check = function () {
   return base58check.encode(this.hash, this.version)
 }
+
+Address.prototype.toScriptPubKey = function() {
+  var scriptType = findScriptTypeByVersion(this.version)
+
+  // Pay-to-pubKeyHash
+  if (scriptType === 'pubKeyHash') {
+    return Script.createPubKeyHashScriptPubKey(this.hash)
+  }
+
+  // Pay-to-scriptHash
+  else if (scriptType === 'scriptHash') {
+    return Script.createP2SHScriptPubKey(this.hash)
+  }
+
+  throw new Error('Address has no matching script')
+}
+
 Address.prototype.toString = Address.prototype.toBase58Check
 
 module.exports = Address
+
+// http://stackoverflow.com/a/14098262
+var Script = require('./script')

src/script.js

@@ -205,13 +205,7 @@ Script.prototype.toScriptHash = function() {
 Script.prototype.getToAddress = function(network) {
   network = network || networks.bitcoin
 
-  if(isPubkeyhash.call(this)) {
-    return new Address(new Buffer(this.chunks[2]), network.pubKeyHash)
-  }
-
-  assert(isScripthash.call(this))
-
-  return new Address(new Buffer(this.chunks[1]), network.scriptHash)
+  return Address.fromScriptPubKey(this, network)
 }
 
 Script.prototype.getFromAddress = function(version) {

test/address.js

@@ -1,15 +1,17 @@
 var assert = require('assert')
 var Address = require('..').Address
+var networks = require('..').networks
+var Script = require('..').Script
 
 var b58fixtures = require('./fixtures/base58')
 var fixtures = require('./fixtures/address')
 
-describe('Address', function() {
-  var bothVectors = fixtures.pubKeyHash.concat(fixtures.scriptHash)
+function h2b(h) { return new Buffer(h, 'hex') }
 
+describe('Address', function() {
   describe('Constructor', function() {
     it('does not mutate the input', function() {
-      bothVectors.forEach(function(f) {
+      fixtures.valid.forEach(function(f) {
         var hash = new Buffer(f.hex, 'hex')
         var addr = new Address(hash, f.version)
 
@@ -28,8 +30,8 @@ describe('Address', function() {
       })
     })
 
-    bothVectors.forEach(function(f) {
-      it('imports ' + f.description + ' correctly', function() {
+    fixtures.valid.forEach(function(f) {
+      it('imports ' + f.description + '(' + f.network + ') correctly', function() {
         var addr = Address.fromBase58Check(f.base58check)
 
         assert.equal(addr.version, f.version)
@@ -38,9 +40,21 @@ describe('Address', function() {
     })
   })
 
+  describe('fromScriptPubKey', function() {
+    fixtures.valid.forEach(function(f) {
+      it('imports ' + f.description + '(' + f.network + ') correctly', function() {
+        var script = Script.fromHex(f.script)
+        var addr = Address.fromScriptPubKey(script, networks[f.network])
+
+        assert.equal(addr.version, f.version)
+        assert.equal(addr.hash.toString('hex'), f.hex)
+      })
+    })
+  })
+
   describe('toBase58Check', function() {
-    bothVectors.forEach(function(f) {
-      it('exports ' + f.description + ' correctly', function() {
+    fixtures.valid.forEach(function(f) {
+      it('exports ' + f.description + '(' + f.network + ') correctly', function() {
         var addr = Address.fromBase58Check(f.base58check)
         var result = addr.toBase58Check()
 
@@ -48,4 +62,25 @@ describe('Address', function() {
       })
     })
   })
+
+  describe('toScriptPubKey', function() {
+    fixtures.valid.forEach(function(f) {
+      it('imports ' + f.description + '(' + f.network + ') correctly', function() {
+        var addr = Address.fromBase58Check(f.base58check)
+        var script = addr.toScriptPubKey()
+
+        assert.equal(script.toHex(), f.script)
+      })
+    })
+
+    fixtures.invalid.toScriptPubKey.forEach(function(f) {
+      it('throws on ' + f.description, function() {
+        var addr = new Address(h2b(f.hex), f.version)
+
+        assert.throws(function() {
+          addr.toScriptPubKey()
+        })
+      })
+    })
+  })
 })

test/fixtures/address.js

@@ -1,30 +1,45 @@
 module.exports = {
-  pubKeyHash: [
+  valid: [
     {
-      description: 'pubKeyHash (bitcoin)',
+      description: 'pubKeyHash',
+      network: 'bitcoin',
       version: 0,
       hex: '751e76e8199196d454941c45d1b3a323f1433bd6',
-      base58check: '1BgGZ9tcN4rm9KBzDn7KprQz87SZ26SAMH'
+      base58check: '1BgGZ9tcN4rm9KBzDn7KprQz87SZ26SAMH',
+      script: '76a914751e76e8199196d454941c45d1b3a323f1433bd688ac'
     },
     {
-      description: 'pubKeyHash (testnet)',
+      description: 'pubKeyHash',
+      network: 'testnet',
       version: 111,
       hex: '751e76e8199196d454941c45d1b3a323f1433bd6',
-      base58check: 'mrCDrCybB6J1vRfbwM5hemdJz73FwDBC8r'
-    }
-  ],
-  scriptHash: [
+      base58check: 'mrCDrCybB6J1vRfbwM5hemdJz73FwDBC8r',
+      script: '76a914751e76e8199196d454941c45d1b3a323f1433bd688ac'
+    },
     {
-      description: 'scriptHash (bitcoin)',
+      description: 'scriptHash',
+      network: 'bitcoin',
       version: 5,
       hex: 'cd7b44d0b03f2d026d1e586d7ae18903b0d385f6',
-      base58check: '3LRW7jeCvQCRdPF8S3yUCfRAx4eqXFmdcr'
+      base58check: '3LRW7jeCvQCRdPF8S3yUCfRAx4eqXFmdcr',
+      script: 'a914cd7b44d0b03f2d026d1e586d7ae18903b0d385f687'
     },
     {
-      description: 'scriptHash (testnet)',
+      description: 'scriptHash',
+      network: 'testnet',
       version: 196,
       hex: 'cd7b44d0b03f2d026d1e586d7ae18903b0d385f6',
-      base58check: '2NByiBUaEXrhmqAsg7BbLpcQSAQs1EDwt5w'
+      base58check: '2NByiBUaEXrhmqAsg7BbLpcQSAQs1EDwt5w',
+      script: 'a914cd7b44d0b03f2d026d1e586d7ae18903b0d385f687'
     }
-  ]
+  ],
+  invalid: {
+    toScriptPubKey: [
+      {
+        description: 'Unknown Address version',
+        version: 0x99,
+        hex: 'cd7b44d0b03f2d026d1e586d7ae18903b0d385f6'
+      }
+    ]
+  }
 }