Clean up param verification code

lib/jsonrpc.py

@@ -304,17 +304,18 @@ class JSONRPC(asyncio.Protocol, LoggedClass):
 
         return await self.json_response(message)
 
-    def method_and_params(self, message):
+    @classmethod
+    def method_and_params(cls, message):
         method = message.get('method')
         params = message.get('params', [])
 
         if not isinstance(method, str):
-            raise self.RPCError('invalid method: {}'.format(method),
-                                self.INVALID_REQUEST)
+            raise cls.RPCError('invalid method: {}'.format(method),
+                               cls.INVALID_REQUEST)
 
         if not isinstance(params, list):
-            raise self.RPCError('params should be an array',
-                                self.INVALID_REQUEST)
+            raise cls.RPCError('params should be an array',
+                               cls.INVALID_REQUEST)
 
         return method, params
 
@@ -349,6 +350,34 @@ class JSONRPC(asyncio.Protocol, LoggedClass):
         raise self.RPCError("unknown method: '{}'".format(method),
                             self.METHOD_NOT_FOUND)
 
+    # Common parameter verification routines
+    @classmethod
+    def param_to_non_negative_integer(cls, param):
+        '''Return param if it is or can be converted to a non-negative
+        integer, otherwise raise an RPCError.'''
+        try:
+            param = int(param)
+            if param >= 0:
+                return param
+        except ValueError:
+            pass
+
+        raise cls.RPCError('param {} should be a non-negative integer'
+                           .format(param))
+
+    @classmethod
+    def params_to_non_negative_integer(cls, params):
+        if len(params) == 1:
+            return cls.param_to_non_negative_integer(params[0])
+        raise cls.RPCError('params {} should contain one non-negative integer'
+                            .format(params))
+
+    @classmethod
+    def require_empty_params(cls, params):
+        if params:
+            raise cls.RPCError('params {} should be empty'.format(params))
+
+
     # --- derived classes are intended to override these functions
     async def handle_notification(self, method, params):
         '''Handle a notification.'''

server/protocol.py

@@ -623,7 +623,7 @@ class Session(JSONRPC):
         except DaemonError as e:
             raise self.RPCError('daemon error: {}'.format(e))
 
-    def tx_hash_from_param(self, param):
+    def param_to_tx_hash(self, param):
         '''Raise an RPCError if the parameter is not a valid transaction
         hash.'''
         if isinstance(param, str) and len(param) == 64:
@@ -635,43 +635,20 @@ class Session(JSONRPC):
         raise self.RPCError('parameter should be a transaction hash: {}'
                             .format(param))
 
-    def hash168_from_param(self, param):
+    def param_to_hash168(self, param):
         if isinstance(param, str):
             try:
                 return self.coin.address_to_hash168(param)
             except:
                 pass
-        raise self.RPCError('parameter should be a valid address: {}'
-                            .format(param))
-
-    def non_negative_integer_from_param(self, param):
-        try:
-            param = int(param)
-        except ValueError:
-            pass
-        else:
-            if param >= 0:
-                return param
+        raise self.RPCError('param {} is not a valid address'.format(param))
 
-        raise self.RPCError('param should be a non-negative integer: {}'
-                            .format(param))
-
-    def extract_hash168(self, params):
+    def params_to_hash168(self, params):
         if len(params) == 1:
-            return self.hash168_from_param(params[0])
-        raise self.RPCError('params should contain a single address: {}'
+            return self.param_to_hash168(params[0])
+        raise self.RPCError('params {} should contain a single address'
                             .format(params))
 
-    def extract_non_negative_integer(self, params):
-        if len(params) == 1:
-            return self.non_negative_integer_from_param(params[0])
-        raise self.RPCError('params should contain a non-negative integer: {}'
-                            .format(params))
-
-    def require_empty_params(self, params):
-        if params:
-            raise self.RPCError('params should be empty: {}'.format(params))
-
 
 class ElectrumX(Session):
     '''A TCP server that handles incoming Electrum connections.'''
@@ -837,27 +814,27 @@ class ElectrumX(Session):
     # --- blockchain commands
 
     async def address_get_balance(self, params):
-        hash168 = self.extract_hash168(params)
+        hash168 = self.params_to_hash168(params)
         return await self.get_balance(hash168)
 
     async def address_get_history(self, params):
-        hash168 = self.extract_hash168(params)
+        hash168 = self.params_to_hash168(params)
         return await self.get_history(hash168)
 
     async def address_get_mempool(self, params):
-        hash168 = self.extract_hash168(params)
+        hash168 = self.params_to_hash168(params)
         return self.unconfirmed_history(hash168)
 
     async def address_get_proof(self, params):
-        hash168 = self.extract_hash168(params)
+        hash168 = self.params_to_hash168(params)
         raise self.RPCError('get_proof is not yet implemented')
 
     async def address_listunspent(self, params):
-        hash168 = self.extract_hash168(params)
+        hash168 = self.params_to_hash168(params)
         return await self.list_unspent(hash168)
 
     async def address_subscribe(self, params):
-        hash168 = self.extract_hash168(params)
+        hash168 = self.params_to_hash168(params)
         if len(self.hash168s) >= self.max_subs:
             raise self.RPCError('your address subscription limit {:,d} reached'
                                 .format(self.max_subs))
@@ -868,11 +845,11 @@ class ElectrumX(Session):
         return result
 
     async def block_get_chunk(self, params):
-        index = self.extract_non_negative_integer(params)
+        index = self.params_to_non_negative_integer(params)
         return self.get_chunk(index)
 
     async def block_get_header(self, params):
-        height = self.extract_non_negative_integer(params)
+        height = self.params_to_non_negative_integer(params)
         return self.electrum_header(height)
 
     async def estimatefee(self, params):
@@ -929,15 +906,15 @@ class ElectrumX(Session):
         # For some reason Electrum passes a height.  Don't require it
         # in anticipation it might be dropped in the future.
         if 1 <= len(params) <= 2:
-            tx_hash = self.tx_hash_from_param(params[0])
+            tx_hash = self.param_to_tx_hash(params[0])
             return await self.daemon_request('getrawtransaction', tx_hash)
 
         raise self.RPCError('params wrong length: {}'.format(params))
 
     async def transaction_get_merkle(self, params):
         if len(params) == 2:
-            tx_hash = self.tx_hash_from_param(params[0])
-            height = self.non_negative_integer_from_param(params[1])
+            tx_hash = self.param_to_tx_hash(params[0])
+            height = self.param_to_non_negative_integer(params[1])
             return await self.tx_merkle(tx_hash, height)
 
         raise self.RPCError('params should contain a transaction hash '
@@ -945,8 +922,8 @@ class ElectrumX(Session):
 
     async def utxo_get_address(self, params):
         if len(params) == 2:
-            tx_hash = self.tx_hash_from_param(params[0])
-            index = self.non_negative_integer_from_param(params[1])
+            tx_hash = self.param_to_tx_hash(params[0])
+            index = self.param_to_non_negative_integer(params[1])
             tx_hash = hex_str_to_hash(tx_hash)
             hash168 = self.bp.get_utxo_hash168(tx_hash, index)
             if hash168: