Add middleware example in scripts

scripts/server.py

@@ -53,9 +53,10 @@ methods = {
     }
 
 
-def jsonrpc_error(id, err):
+def jsonrpc_error(rpc_id, err):
     return {
             'json-rpc': '2.0',
+            'id': rpc_id,
             'error': {
                 'code': err.CODE,
                 'message': err.MESSAGE,
@@ -71,6 +72,12 @@ def jsonrpc_ok(rpc_id, response):
             }
 
 
+def is_valid_json(j):
+    if j.get('id') == 'None':
+        raise ValueError('id missing')
+    return True
+
+
 def process_input(j):
 
     rpc_id = j['id']
@@ -81,20 +88,33 @@ def process_input(j):
 
 
 def start_server():
-    os.unlink('/tmp/foo.ipc')
+    try:
+        os.unlink('/tmp/foo.ipc')
+    except FileNotFoundError:
+        pass
     s = socket.socket(family = socket.AF_UNIX, type = socket.SOCK_STREAM)
     s.bind('/tmp/foo.ipc')
     s.listen(10)
     while True:
         (csock, caddr) = s.accept()
         d = csock.recv(4096)
+        j = None
         try:
-            j = json.loads(b)
-            process_input(j)
+            j = json.loads(d)
+            is_valid_json(j)
             logg.debug('{}'.format(d.decode('utf-8')))
-            csock.send(json.dumps(jsonrpc_ok(0, [])).encode('utf-8'))
         except:
             csock.send(json.dumps(jsonrpc_error(None, JSONRPCParseError)).encode('utf-8'))
+            csock.close()
+            continue
+
+        try:
+            (rpc_id, r) = process_input(j)
+            csock.send(json.dumps(jsonrpc_ok(rpc_id, r)).encode('utf-8'))
+        except:
+            # TODO: handle cases to give better error context to caller
+            csock.send(json.dumps(jsonrpc_error(j['id'], JSONRPCServerError)).encode('utf-8'))
+
         csock.close()
     s.close()
 

scripts/web3_middleware.py

@@ -0,0 +1,81 @@
+import logging
+import re
+import socket
+import uuid
+import json
+
+from web3 import Web3, WebsocketProvider, IPCProvider
+
+
+logging.basicConfig(level=logging.DEBUG)
+logg = logging.getLogger('foo')
+
+
+def jsonrpc_request(method, params):
+    uu = uuid.uuid4()
+    return {
+        "jsonrpc": "2.0",
+        "id": str(uu),
+        "method": method,
+        "params": params,
+            }
+
+class PlatformMiddleware:
+
+    # id for the request is not available, meaning we cannot easily short-circuit
+    # hack workaround
+    id_seq = -1
+    re_personal = re.compile('^personal_.*')
+    ipcaddr = '/tmp/foo.ipc'
+
+
+    def __init__(self, make_request, w3):
+        self.w3 = w3 
+        self.make_request = make_request
+
+
+    # single entry input gives a tuple on params, wtf...
+    @staticmethod
+    def _translate_params(params):
+        if params.__class__.__name__ == 'tuple':
+            r = []
+            for p in params:
+                r.append(p)
+            return r
+
+
+    def __call__(self, method, suspect_params):
+        self.id_seq += 1
+        params = PlatformMiddleware._translate_params(suspect_params)
+
+        logg.debug('method {} params {} original params {}'.format(method, params, suspect_params))
+        if self.re_personal.match(method) != None:
+            # multiple providers is broken in web3.py 5.12.0
+            # https://github.com/ethereum/web3.py/issues/1701
+            # hack workaround
+            s = socket.socket(family=socket.AF_UNIX, type=socket.SOCK_STREAM, proto=0)
+            ipc_provider_workaround = s.connect(self.ipcaddr)
+
+            logg.debug('redirecting method {}'.format(method))
+            o = jsonrpc_request(method, params)
+            j = json.dumps(o)
+            logg.debug('send {}'.format(j))
+            s.send(j.encode('utf-8'))
+            r = s.recv(4096)
+            s.close()
+            logg.debug('got recv {}'.format(str(r)))
+            jr = json.loads(r)
+            jr['id'] = self.id_seq
+            #return str(json.dumps(jr))
+            return jr
+
+        r = self.make_request(method, params)
+        logg.debug('retular response {}'.format(r))
+        return r
+
+
+w3 = Web3(WebsocketProvider('ws://127.0.0.1:8546'))
+w3.eth.personal = w3.geth.personal
+w3.middleware_onion.add(PlatformMiddleware)
+print(w3.eth.personal.newAccount('foo'))
+#print(w3.eth.blockNumber)