expose limits, add tests and fix all the bugs they exposed

asyncua/common/connection.py

@@ -50,13 +50,17 @@ class TransportLimits:
             logger.error("Number of message chunks: %s is > configured max chunk count: %s", sz, self.max_chunk_count)
         return within_limit
 
-    def create_acknowledge_limits(self, msg: ua.Hello) -> ua.Acknowledge:
+    def create_acknowledge_and_set_limits(self, msg: ua.Hello) -> ua.Acknowledge:
         ack = ua.Acknowledge()
-        ack.ReceiveBufferSize = min(msg.ReceiveBufferSize, self.max_recv_buffer)
-        ack.SendBufferSize = min(msg.SendBufferSize, self.max_send_buffer)
+        ack.ReceiveBufferSize = min(msg.ReceiveBufferSize, self.max_send_buffer)
+        ack.SendBufferSize = min(msg.SendBufferSize, self.max_recv_buffer)
         ack.MaxChunkCount = self._select_limit(msg.MaxChunkCount, self.max_chunk_count)
         ack.MaxMessageSize = self._select_limit(msg.MaxMessageSize, self.max_message_size)
-        self.update_limits(ack)
+        self.max_chunk_count = ack.MaxChunkCount
+        self.max_recv_buffer = ack.SendBufferSize
+        self.max_send_buffer = ack.ReceiveBufferSize
+        self.max_message_size = ack.MaxMessageSize
+        logger.warning("updating server limits to: %s", self)
         return ack
 
     def create_hello_limits(self, msg: ua.Hello) -> ua.Hello:
@@ -65,12 +69,12 @@ class TransportLimits:
         msg.MaxChunkCount = self.max_chunk_count
         msg.MaxMessageSize = self.max_chunk_count
 
-    def update_limits(self, msg: ua.Acknowledge) -> None:
+    def update_client_limits(self, msg: ua.Acknowledge) -> None:
         self.max_chunk_count = msg.MaxChunkCount
         self.max_recv_buffer = msg.ReceiveBufferSize
         self.max_send_buffer = msg.SendBufferSize
         self.max_message_size = msg.MaxMessageSize
-        logger.warning("updating limits to: %s", self)
+        logger.warning("updating client limits to: %s", self)
 
 
 class MessageChunk:
@@ -415,7 +419,7 @@ class SecureConnection:
             return msg
         if header.MessageType == ua.MessageType.Acknowledge:
             msg = struct_from_binary(ua.Acknowledge, body)
-            self._limits.update_limits(msg)
+            self._limits.update_client_limits(msg)
             return msg
         if header.MessageType == ua.MessageType.Error:
             msg = struct_from_binary(ua.ErrorMessage, body)

asyncua/server/binary_server_asyncio.py

@@ -3,7 +3,6 @@ Socket server forwarding request to internal server
 """
 import logging
 import asyncio
-import math
 from typing import Optional
 
 from ..common.connection import TransportLimits
@@ -68,9 +67,8 @@ class OPCUAProtocol(asyncio.Protocol):
                 try:
                     header = header_from_binary(buf)
                 except NotEnoughData:
-                    # a packet should at least contain a header otherwise it is malformed (8 or 12 bytes)
-                    logger.debug('Not enough data while parsing header from client, empty the buffer')
-                    self.transport.close()
+                    # we jsut wait for more data, that happens.
+                    # worst case recv will go in timeout or it hangs and it should be fine too
                     return
                 if header.header_size + header.body_size <= header.header_size:
                     # malformed header prevent invalid access of your buffer
@@ -78,8 +76,7 @@ class OPCUAProtocol(asyncio.Protocol):
                     self.transport.close()
                 else:
                     if len(buf) < header.body_size:
-                        logger.debug('We did not receive enough data from client. Need %s got %s', header.body_size,
-                                    len(buf))
+                        logger.debug('We did not receive enough data from client. Need %s got %s', header.body_size, len(buf))
                         return
                     # we have a complete message
                     self.messages.put_nowait((header, buf))
@@ -112,7 +109,7 @@ class OPCUAProtocol(asyncio.Protocol):
 
 
 class BinaryServer:
-    def __init__(self, internal_server: InternalServer, hostname, port):
+    def __init__(self, internal_server: InternalServer, hostname, port, limits: TransportLimits):
         self.logger = logging.getLogger(__name__)
         self.hostname = hostname
         self.port = port
@@ -122,15 +119,7 @@ class BinaryServer:
         self.clients = []
         self.closing_tasks = []
         self.cleanup_task = None
-        # Use accectable limits
-        buffer_sz = 65535
-        max_msg_sz = 16 * 1024 * 1024  # 16mb simular to the opc ua c stack so this is a good default
-        self.limits = TransportLimits(
-            max_recv_buffer=buffer_sz,
-            max_send_buffer=buffer_sz,
-            max_chunk_count=math.ceil(buffer_sz / max_msg_sz),  # Round up to allow max msg size
-            max_message_size=max_msg_sz
-        )
+        self.limits = limits
 
     def set_policies(self, policies):
         self._policies = policies

asyncua/server/server.py

@@ -4,6 +4,7 @@ High level interface to pure python OPC-UA server
 
 import asyncio
 import logging
+import math
 from datetime import timedelta, datetime
 from urllib.parse import urlparse
 from typing import Coroutine, Optional, Tuple
@@ -23,6 +24,7 @@ from ..common.shortcuts import Shortcuts
 from ..common.structures import load_type_definitions, load_enums
 from ..common.structures104 import load_data_type_definitions
 from ..common.ua_utils import get_nodes_of_namespace
+from ..common.connection import TransportLimits
 
 from ..crypto import security_policies, uacrypto
 
@@ -104,6 +106,15 @@ class Server:
         self._permission_ruleset = None
         self._policyIDs = ["Anonymous", "Basic256Sha256", "Username", "Aes128Sha256RsaOaep"]
         self.certificate = None
+        # Use accectable limits
+        buffer_sz = 65535
+        max_msg_sz = 100 * 1024 * 1024  # 100mb
+        self.limits = TransportLimits(
+            max_recv_buffer=buffer_sz,
+            max_send_buffer=buffer_sz,
+            max_chunk_count=math.ceil(max_msg_sz / buffer_sz),  # Round up to allow max msg size
+            max_message_size=max_msg_sz
+        )
 
     async def init(self, shelf_file=None):
         await self.iserver.init(shelf_file)
@@ -425,7 +436,7 @@ class Server:
         await self.iserver.start()
         try:
             ipaddress, port = self._get_bind_socket_info()
-            self.bserver = BinaryServer(self.iserver, ipaddress, port)
+            self.bserver = BinaryServer(self.iserver, ipaddress, port, self.limits)
             self.bserver.set_policies(self._policies)
             await self.bserver.start()
         except Exception as exp:

asyncua/server/uaprocessor.py

@@ -109,7 +109,7 @@ class UaProcessor:
             elif header.MessageType == ua.MessageType.SecureMessage:
                 return await self.process_message(msg.SequenceHeader(), msg.body())
         elif isinstance(msg, ua.Hello):
-            ack = self._limits.create_acknowledge_limits(msg)
+            ack = self._limits.create_acknowledge_and_set_limits(msg)
             data = uatcp_to_binary(ua.MessageType.Acknowledge, ack)
             self._transport.write(data)
         elif isinstance(msg, ua.ErrorMessage):

examples/client-limits.py

+import asyncio
+import logging
+
+from asyncua import Client
+
+url = "opc.tcp://localhost:4840/freeopcua/server/"
+namespace = "http://examples.freeopcua.github.io"
+
+
+async def main():
+
+    print(f"Connecting to {url} ...")
+    async with Client(url=url, watchdog_intervall=1000) as client:
+        # Find the namespace index
+        nsidx = await client.get_namespace_index(namespace)
+        print(f"Namespace Index for '{namespace}': {nsidx}")
+
+        # Get the variable node for read / write
+        var = await client.nodes.root.get_child(
+            ["0:Objects", f"{nsidx}:MyObject", f"{nsidx}:MyVariable"]
+        )
+        print("READ!!!!!!!!!!!!!!!!!")
+        value = await var.read_value()
+        print("Received value of length !!!!!!!!!!!!!!!!!!!!!", len(value))
+
+        print("writting back value of MyVariable ")
+        await var.write_value(value)
+
+
+if __name__ == "__main__":
+
+    logging.basicConfig(level=logging.WARNING)
+    asyncio.run(main())

examples/server-limits.py

+import asyncio
+import logging
+
+from asyncua import Server, ua
+from asyncua.common.methods import uamethod
+
+
+@uamethod
+def func(parent, value):
+    return value * 2
+
+
+async def main():
+    _logger = logging.getLogger("asyncua")
+    # setup our server
+    server = Server()
+
+    # set some hard connection limits
+    #server.limits.max_recv_buffer = 1024
+    #server.limits.max_send_buffer = 1024
+    #server.limits.max_send_buffer = 102400000000
+    server.limits.max_chunk_count = 10
+    print(server.limits)
+    await server.init()
+    server.set_endpoint("opc.tcp://0.0.0.0:4840/freeopcua/server/")
+
+    # setup our own namespace, not really necessary but should as spec
+    uri = "http://examples.freeopcua.github.io"
+    idx = await server.register_namespace(uri)
+
+    # populating our address space
+    # setup a variable far too big for our limits
+    test_string = b'a' * (100 * 1024 * 1024)
+    test_string = b'a' * 100 * 1024
+    print("LENGTH VAR", len(test_string))
+    myobj = await server.nodes.objects.add_object(idx, "MyObject")
+    myvar = await myobj.add_variable(idx, "MyVariable", test_string)
+    # Set MyVariable to be writable by clients
+    await myvar.set_writable()
+    _logger.info("Starting server!")
+    async with server:
+        while True:
+            await asyncio.sleep(1)
+
+
+if __name__ == "__main__":
+    logging.basicConfig(level=logging.WARNING)
+    asyncio.run(main(), debug=False)

tests/test_server.py

@@ -677,24 +677,43 @@ def restore_transport_limits_server(server: Server):
     server.bserver.limits.max_chunk_count = max_chunk_count
 
 
-async def test_message_limits(restore_transport_limits_server: Server):
+async def test_message_limits_fail_write(restore_transport_limits_server: Server):
     server = restore_transport_limits_server
     server.bserver.limits.max_recv_buffer = 1024
+    server.bserver.limits.max_send_buffer = 10240000
     server.bserver.limits.max_chunk_count = 10
-    n = await server.nodes.objects.add_variable(1, "MyLimitVariable", "t")
+    test_string = b'a' * 100 * 1024
+    n = await server.nodes.objects.add_variable(1, "MyLimitVariable", test_string)
     await n.set_writable(True)
     client = Client(server.endpoint.geturl())
     # This should trigger a timeout error because the message is to large
-    with pytest.raises(ConnectionError):
-        async with client:
-            test_string = 'a' * (1024 * 1024 * 1024)
-            n = client.get_node(n.nodeid)
-            await n.write_value(test_string, ua.VariantType.String)
+    async with client:
+        n = client.get_node(n.nodeid)
+        await n.read_value()
+        with pytest.raises(ConnectionError):
+            await n.write_value(test_string, ua.VariantType.ByteString)
+
+
+async def test_message_limits_fail_read(restore_transport_limits_server: Server):
+    server = restore_transport_limits_server
+    server.bserver.limits.max_recv_buffer = 10240000
+    server.bserver.limits.max_send_buffer = 1024
+    server.bserver.limits.max_chunk_count = 10
+    test_string = b'a' * 100 * 1024
+    n = await server.nodes.objects.add_variable(1, "MyLimitVariable", test_string)
+    await n.set_writable(True)
+    client = Client(server.endpoint.geturl())
+    # This should trigger a connection error because the message is to large
+    async with client:
+        n = client.get_node(n.nodeid)
+        await n.write_value(test_string, ua.VariantType.ByteString)
+        with pytest.raises(ConnectionError):
+            await n.read_value()
 
 
 async def test_message_limits_works(restore_transport_limits_server: Server):
     server = restore_transport_limits_server
-    server.bserver.limits.max_recv_buffer = 1024
+    # server.bserver.limits.max_recv_buffer = 1024
     server.bserver.limits.max_send_buffer = 1024
     server.bserver.limits.max_chunk_count = 10
     n = await server.nodes.objects.add_variable(1, "MyLimitVariable2", "t")
@@ -705,6 +724,7 @@ async def test_message_limits_works(restore_transport_limits_server: Server):
         n = client.get_node(n.nodeid)
         test_string = 'a' * (1024 * 5)
         await n.write_value(test_string, ua.VariantType.String)
+        await n.read_value()