Support names in "query" RPC command. (#875)

This extends the "query" RPC command so that it also allows querying
for the name index in Namecoin (and potential future coins that support
a name index as well).

Previously, that was not possible even when passing the normalised
script itself:  In that case, hashX_from_script would strip off the name
prefix again, and thus the query would only be for OP_RETURN.  (Thanks to
JeremyRand for analysing this bug!)

docs/rpc-interface.rst

@@ -204,7 +204,8 @@ query
 -----
 
 Run a query of the UTXO and history databases against one or more
-addresses or hex scripts.  `--limit <N>` or `-l <N>` limits the output
+addresses, hex scripts or ASCII names (for coins that have an index
+on names like Namecoin).  `--limit <N>` or `-l <N>` limits the output
 for each kind to that many entries.  History is printed in blockchain
 order; UTXOs in an arbitrary order.
 

electrumx/lib/coins.py

@@ -942,6 +942,27 @@ class Namecoin(NameMixin, AuxPowMixin, Coin):
     ]
     BLOCK_PROCESSOR = block_proc.NamecoinBlockProcessor
 
+    # Name opcodes
+    OP_NAME_NEW = OpCodes.OP_1
+    OP_NAME_FIRSTUPDATE = OpCodes.OP_2
+    OP_NAME_UPDATE = OpCodes.OP_3
+
+    @classmethod
+    def build_name_index_script(cls, name):
+        """Returns the normalised script by which names are indexed"""
+
+        from electrumx.lib.script import Script
+
+        normalized_name_op_script = bytearray()
+        normalized_name_op_script.append(cls.OP_NAME_UPDATE)
+        normalized_name_op_script.extend(Script.push_data(name))
+        normalized_name_op_script.extend(Script.push_data(bytes([])))
+        normalized_name_op_script.append(OpCodes.OP_2DROP)
+        normalized_name_op_script.append(OpCodes.OP_DROP)
+        normalized_name_op_script.append(OpCodes.OP_RETURN)
+
+        return bytes(normalized_name_op_script)
+
     @classmethod
     def split_name_script(cls, script):
         from electrumx.lib.script import _match_ops, Script, ScriptError
@@ -953,16 +974,11 @@ class Namecoin(NameMixin, AuxPowMixin, Coin):
 
         match = _match_ops
 
-        # Name opcodes
-        OP_NAME_NEW = OpCodes.OP_1
-        OP_NAME_FIRSTUPDATE = OpCodes.OP_2
-        OP_NAME_UPDATE = OpCodes.OP_3
-
         # Opcode sequences for name operations
-        NAME_NEW_OPS = [OP_NAME_NEW, -1, OpCodes.OP_2DROP]
-        NAME_FIRSTUPDATE_OPS = [OP_NAME_FIRSTUPDATE, -1, -1, -1,
+        NAME_NEW_OPS = [cls.OP_NAME_NEW, -1, OpCodes.OP_2DROP]
+        NAME_FIRSTUPDATE_OPS = [cls.OP_NAME_FIRSTUPDATE, -1, -1, -1,
                                 OpCodes.OP_2DROP, OpCodes.OP_2DROP]
-        NAME_UPDATE_OPS = [OP_NAME_UPDATE, -1, -1, OpCodes.OP_2DROP,
+        NAME_UPDATE_OPS = [cls.OP_NAME_UPDATE, -1, -1, OpCodes.OP_2DROP,
                            OpCodes.OP_DROP]
 
         name_script_op_count = None
@@ -991,14 +1007,7 @@ class Namecoin(NameMixin, AuxPowMixin, Coin):
         if name_pushdata is None:
             return None, address_script
 
-        normalized_name_op_script = bytearray()
-        normalized_name_op_script.append(OP_NAME_UPDATE)
-        normalized_name_op_script.extend(Script.push_data(name_pushdata[1]))
-        normalized_name_op_script.extend(Script.push_data(bytes([])))
-        normalized_name_op_script.append(OpCodes.OP_2DROP)
-        normalized_name_op_script.append(OpCodes.OP_DROP)
-        normalized_name_op_script.append(OpCodes.OP_RETURN)
-
+        normalized_name_op_script = cls.build_name_index_script(name_pushdata[1])
         return bytes(normalized_name_op_script), address_script
 
     @classmethod

electrumx/server/session.py

@@ -490,7 +490,7 @@ class SessionManager:
         return self.peer_mgr.rpc_data()
 
     async def rpc_query(self, items, limit):
-        '''Return a list of data about server peers.'''
+        '''Returns data about a script, address or name.'''
         coin = self.env.coin
         db = self.db
         lines = []
@@ -505,11 +505,20 @@ class SessionManager:
 
             try:
                 hashX = coin.address_to_hashX(arg)
-            except Base58Error as e:
-                lines.append(e.args[0])
-                return None
-            lines.append(f'Address: {arg}')
-            return hashX
+                lines.append(f'Address: {arg}')
+                return hashX
+            except Base58Error:
+                pass
+
+            try:
+                script = coin.build_name_index_script(arg.encode("ascii"))
+                hashX = coin.name_hashX_from_script(script)
+                lines.append(f'Name: {arg}')
+                return hashX
+            except (AttributeError, UnicodeEncodeError):
+                pass
+
+            return None
 
         for arg in items:
             hashX = arg_to_hashX(arg)