No localEndpoint info after starting NWConnection in macOS 14.2 (23C5030f)

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Created Nov ’23

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We have code inside our network extension to create NWConnection with destination to loopback address 127.0.0.1 with a specific port number that another process is listening to. This method has been working fine until we test it on macOS 14.2 Beta (23C5030f) where we observed the following error: (Network) [com.apple.network:connection] nw_connection_copy_connected_local_endpoint_block_invoke [C42] Connection has no local endpoint and accessing the connection.currentPath.localEndpoint would return nil. This eventually leads to connection failure.

This error is only observed with connection to loopback address. NWConnection created with destination to real address (Eg. on en0 interface) does not have any issue.

This error is not observed with all connections to loopback address. Some NWConnection objects would still contain the localEndpoint.

Here is an example of all log messages we get for a specific connection:

(Network) [com.apple.network:connection] [C42 D9F43B3D-6832-4581-9B3B-12F6F5C7C408 127.0.0.1:49154 tcp, attribution: developer, context: Default Network Context (private), proc: 0D165C5B-CDFE-3F43-BC52-1DFCD61739E6, prefer no proxy] start
(Network) [com.apple.network:connection] [C42 127.0.0.1:49154 initial parent-flow ((null))] event: path:start @0.000s
(Network) [com.apple.network:connection] [C42 127.0.0.1:49154 waiting parent-flow (satisfied (Path is satisfied), viable, interface: lo0)] event: path:satisfied @0.000s, uuid: 6655EA53-47F9-4B16-85D6-7B81FA0C360E
(Network) [com.apple.network:connection] [C42 127.0.0.1:49154 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: lo0)] event: flow:start_connect @0.000s
(Network) [com.apple.network:connection] nw_connection_report_state_with_handler_on_nw_queue [C42] reporting state preparing
(Network) [com.apple.network:connection] nw_socket_handle_socket_event [C42:1] Socket received CONNECTED event
(Network) [com.apple.network:connection] nw_flow_connected [C42 127.0.0.1:49154 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: lo0)] Output protocol connected (socket)
(Network) [com.apple.network:connection] [C42 127.0.0.1:49154 ready socket-flow (satisfied (Path is satisfied), viable, interface: lo0)] event: flow:finish_connect @0.000s
(Network) [com.apple.network:connection] nw_connection_report_state_with_handler_on_nw_queue [C42] reporting state ready
(Network) [com.apple.network:connection] [C42 D9F43B3D-6832-4581-9B3B-12F6F5C7C408 127.0.0.1:49154 tcp, prefer no proxy, attribution: developer] cancel
(Network) [com.apple.network:connection] nw_connection_copy_connected_local_endpoint_block_invoke [C42] Connection has no local endpoint
(Network) [com.apple.network:connection] [C42 D9F43B3D-6832-4581-9B3B-12F6F5C7C408 127.0.0.1:49154 tcp, prefer no proxy, attribution: developer] cancelled
    [C42 6655EA53-47F9-4B16-85D6-7B81FA0C360E <NULL><->127.0.0.1:49154]
    Connected Path: satisfied (Path is satisfied), interface: lo0
    Privacy Stance: Not Eligible
    Duration: 0.001s, TCP @0.000s took 0.000s
    bytes in/out: 0/0, packets in/out: 0/0, rtt: 0.001s, retransmitted bytes: 0, out-of-order bytes: 0
    ecn packets sent/acked/marked/lost: 0/0/0/0

Questions:

Why is loopback address special in this case as issue is only observed with connections to loopback address?
What we should do in terms of updating our code inside network extension to get this working in macOS 14.2?

Boost

Answer 1

Tianqiw OP

Nov ’23

Some additional info: we have tested the same code on both Intel and M1 machine and the issue is only observed on the M1 machine.

Would there be any reason that different architectures made a difference?

0

Answer 2

AlexPuskas OP

Nov ’23

We observed the same behaviour. Before macOS 14.2 we were able to get the local endpoint on the ready state of a NWConnection:

let localEndpoint = connection.currentPath?.localEndpoint?.neEndpoint

where connection is a NWConnection with the destination set to localhost, and the above code is called from the connection state update handler for connection when the connection state is updated to ready

After upgrading to macOS 14.2 Beta, the local endpoint retrieved by the above code is NIL.

Other important aspect related to connection.debugDescription

when works as expected the following is displayed:


connection info [C598 connected 127.0.0.1:27443 tcp, attribution: developer, path satisfied (Path is satisfied), viable, interface: lo0]

when not works as expected, the viable attribution is NOT displayed:

connection info [C603 connected 127.0.0.1:27443 tcp, attribution: developer, path satisfied (Path is satisfied), interface: lo0]

Can we somehow obtain/detect the localEndpoint for a network connection?

0

Answer 3

Tianqiw OP

Nov ’23

This issue is no longer observed in macOS Sonoma 14.2 Beta 3 (23C5047e).

0