Allow Bitcoin URI's that don't have any address component if the r= payment protocol param is there.

core/src/main/java/com/google/bitcoin/uri/BitcoinURI.java

@@ -149,10 +149,9 @@ public class BitcoinURI {
 
         // Split off the address from the rest of the query parameters.
         String[] addressSplitTokens = schemeSpecificPart.split("\\?");
-        if (addressSplitTokens.length == 0 || "".equals(addressSplitTokens[0])) {
-            throw new BitcoinURIParseException("Missing address");
-        }
-        String addressToken = addressSplitTokens[0];
+        if (addressSplitTokens.length == 0)
+            throw new BitcoinURIParseException("No data found after the bitcoin: prefix");
+        String addressToken = addressSplitTokens[0];  // may be empty!
 
         String[] nameValuePairTokens;
         if (addressSplitTokens.length == 1) {
@@ -169,6 +168,20 @@ public class BitcoinURI {
 
         // Attempt to parse the rest of the URI parameters.
         parseParameters(params, addressToken, nameValuePairTokens);
+
+        if (!addressToken.isEmpty()) {
+            // Attempt to parse the addressToken as a Bitcoin address for this network
+            try {
+                Address address = new Address(params, addressToken);
+                putWithValidation(FIELD_ADDRESS, address);
+            } catch (final AddressFormatException e) {
+                throw new BitcoinURIParseException("Bad address", e);
+            }
+        }
+
+        if (addressToken.isEmpty() && getPaymentRequestUrl() == null) {
+            throw new BitcoinURIParseException("No address and no r= parameter found");
+        }
     }
 
     /**
@@ -177,14 +190,6 @@ public class BitcoinURI {
      *                            separated by '=' e.g. 'amount=0.2')
      */
     private void parseParameters(@Nullable NetworkParameters params, String addressToken, String[] nameValuePairTokens) throws BitcoinURIParseException {
-        // Attempt to parse the addressToken as a Bitcoin address for this network
-        try {
-            Address address = new Address(params, addressToken);
-            putWithValidation(FIELD_ADDRESS, address);
-        } catch (final AddressFormatException e) {
-            throw new BitcoinURIParseException("Bad address", e);
-        }
-        
         // Attempt to decode the rest of the tokens into a parameter map.
         for (String nameValuePairToken : nameValuePairTokens) {
             String[] tokens = nameValuePairToken.split("=");
@@ -242,8 +247,11 @@ public class BitcoinURI {
     }
 
     /**
-     * @return The Bitcoin Address from the URI
+     * The Bitcoin Address from the URI, if one was present. It's possible to have Bitcoin URI's with no address if a
+     * r= payment protocol parameter is specified, though this form is not recommended as older wallets can't understand
+     * it.
      */
+    @Nullable
     public Address getAddress() {
         return (Address) parameterMap.get(FIELD_ADDRESS);
     }

core/src/test/java/com/google/bitcoin/uri/BitcoinURITest.java

@@ -240,7 +240,7 @@ public class BitcoinURITest {
         testObject = new BitcoinURI(MainNetParams.get(), BitcoinURI.BITCOIN_SCHEME + ":" + MAINNET_GOOD_ADDRESS
                 + "?amount=6543210&label=Hello%20World&message=Be%20well");
         assertEquals(
-                "BitcoinURI['address'='1KzTSfqjF2iKCduwz59nv2uqh1W2JsTxZH','amount'='654321000000000','label'='Hello World','message'='Be well']",
+                "BitcoinURI['amount'='654321000000000','label'='Hello World','message'='Be well','address'='1KzTSfqjF2iKCduwz59nv2uqh1W2JsTxZH']",
                 testObject.toString());
     }
 
@@ -367,7 +367,7 @@ public class BitcoinURITest {
         // Unknown not required field
         testObject = new BitcoinURI(MainNetParams.get(), BitcoinURI.BITCOIN_SCHEME + ":" + MAINNET_GOOD_ADDRESS
                 + "?aardvark=true");
-        assertEquals("BitcoinURI['address'='1KzTSfqjF2iKCduwz59nv2uqh1W2JsTxZH','aardvark'='true']", testObject.toString());
+        assertEquals("BitcoinURI['aardvark'='true','address'='1KzTSfqjF2iKCduwz59nv2uqh1W2JsTxZH']", testObject.toString());
 
         assertEquals("true", (String) testObject.getParameterByName("aardvark"));
 
@@ -416,4 +416,12 @@ public class BitcoinURITest {
         new BitcoinURI(MainNetParams.get(), BitcoinURI.BITCOIN_SCHEME + ":" + MAINNET_GOOD_ADDRESS
                 + "?amount=100000000");
     }
+
+    @Test
+    public void testPaymentProtocolReq() throws Exception {
+        // Non-backwards compatible form ...
+        BitcoinURI uri = new BitcoinURI(TestNet3Params.get(), "bitcoin:?r=https%3A%2F%2Fbitcoincore.org%2F%7Egavin%2Ff.php%3Fh%3Db0f02e7cea67f168e25ec9b9f9d584f9");
+        assertEquals("https://bitcoincore.org/~gavin/f.php?h=b0f02e7cea67f168e25ec9b9f9d584f9", uri.getPaymentRequestUrl());
+        assertNull(uri.getAddress());
+    }
 }

tools/src/main/java/com/google/bitcoin/tools/WalletTool.java

@@ -506,7 +506,7 @@ public class WalletTool {
             try {
                 paymentRequestURI = new BitcoinURI(location);
             } catch (BitcoinURIParseException e) {
-                System.err.println("Invalid bitcoin uri " + e.getMessage());
+                System.err.println("Invalid bitcoin uri: " + e.getMessage());
                 System.exit(1);
             }
             try {