From be2475f61765e1e0202f446a4137ba859b1c7fe8 Mon Sep 17 00:00:00 2001
From: Neil Booth <kyuupichan@gmail.com>
Date: Thu, 3 Nov 2016 10:46:09 +0900
Subject: [PATCH] Handle utxo.get_address

---
 lib/coins.py              |  5 +++++
 server/block_processor.py |  9 +++++++++
 server/controller.py      |  7 +++----
 server/protocol.py        | 17 +++++++++++++++--
 4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/lib/coins.py b/lib/coins.py
index ec84b96..5c89832 100644
--- a/lib/coins.py
+++ b/lib/coins.py
@@ -77,6 +77,11 @@ class Coin(object):
             raise CoinError('invalid address: {}'.format(addr))
         return result
 
+    @classmethod
+    def hash168_to_address(cls, hash168):
+        '''Return an address given a 21-byte hash.'''
+        return Base58.encode_check(hash168)
+
     @classmethod
     def P2PKH_address_from_hash160(cls, hash_bytes):
         '''Return a P2PKH address given a public key.'''
diff --git a/server/block_processor.py b/server/block_processor.py
index 47aa0e1..908b245 100644
--- a/server/block_processor.py
+++ b/server/block_processor.py
@@ -762,3 +762,12 @@ class BlockProcessor(LoggedClass):
         '''Returns all the UTXOs for an address sorted by height and
         position in the block.'''
         return sorted(self.get_utxos(hash168, limit=None))
+
+    def get_utxo_hash168(self, tx_hash, index):
+        '''Returns the hash168 for a UTXO.'''
+        hash168 = None
+        if 0 <= index <= 65535:
+            hash168 = self.utxo_cache(tx_hash, struct.pack('<H', index))
+            if hash168 == NO_CACHE_ENTRY:
+                hash168 = None
+        return hash168
diff --git a/server/controller.py b/server/controller.py
index 898523a..7519a17 100644
--- a/server/controller.py
+++ b/server/controller.py
@@ -17,11 +17,10 @@ import ssl
 import traceback
 from functools import partial
 
-from server.daemon import Daemon, DaemonError
+from server.daemon import Daemon
 from server.block_processor import BlockProcessor
-from server.protocol import ElectrumX, LocalRPC, RPCError, JSONRPC
-from lib.hash import (sha256, double_sha256, hash_to_str,
-                      Base58, hex_str_to_hash)
+from server.protocol import ElectrumX, LocalRPC, JSONRPC
+from lib.hash import sha256, double_sha256, hash_to_str, hex_str_to_hash
 from lib.util import LoggedClass
 
 
diff --git a/server/protocol.py b/server/protocol.py
index acedfea..925d9b2 100644
--- a/server/protocol.py
+++ b/server/protocol.py
@@ -16,6 +16,7 @@ import traceback
 from functools import partial
 
 from server.daemon import DaemonError
+from lib.hash import hex_str_to_hash
 from lib.util import LoggedClass
 from server.version import VERSION
 
@@ -201,6 +202,8 @@ class JSONRPC(asyncio.Protocol, LoggedClass):
             'blockchain.numblocks.subscribe',
             (height, ),
         )
+        hash168_to_address = cls.COIN.hash168_to_address
+
         for session in cls.SESSIONS:
             if height != session.notified_height:
                 session.notified_height = height
@@ -210,8 +213,9 @@ class JSONRPC(asyncio.Protocol, LoggedClass):
                     session.json_send(height_payload)
 
             for hash168 in session.hash168s.intersection(touched):
+                address = hash168_to_address(hash168)
                 payload = json_notification('blockchain.address.subscribe',
-                                            (Base58.encode_check(hash168), ))
+                                            (address, ))
                 session.json_send(payload)
 
 
@@ -347,7 +351,16 @@ class ElectrumX(JSONRPC):
         raise RPCError('params should contain a transaction hash and height')
 
     async def utxo_get_address(self, params):
-        pass # TODO
+        if len(params) == 2:
+            tx_hash = self.tx_hash_from_param(params[0])
+            index = self.non_negative_integer_from_param(params[1])
+            tx_hash = hex_str_to_hash(tx_hash)
+            hash168 = self.BLOCK_PROCESSOR.get_utxo_hash168(tx_hash, index)
+            if hash168:
+                return self.COIN.hash168_to_address(hash168)
+            return None
+
+        raise RPCError('params should contain a transaction hash and index')
 
     # --- server commands