feat(elixir): add unix domain sockets transport and getting-started example #4220

tzumby · 2023-02-07T17:08:40Z

Current Behavior

Currently there is no implementation of Unix Domain Socket Transports for Elixir implementation.

Proposed Changes

This PR is still Work in Progress

Prototype the unix domain sockets transport
Add examples
Add tests
Clean up sockets after crashes / shutdown
Allow multiple UDS gen_tcp servers to run (currently using named processes for the Connection supervision)

       +-----------------+                                                                 
       | UDS(Supervisor) |                                                                 
       +--------/----\---+                                                                 
               /      \                                                                    
              /        \                                                                   
             /       +-----------+                                                         
            /        | Listener  --------|                                                 
           /         +-----------+       |                                                 
          /                              | Start Connection children                       
   +-----------------------+             |                                                 
   |Connection Supervisor  --------------|                                                 
   |(dynamic)              |                                                               
   +------/----------\-----+                                                               
         /            \                                                                    
        /              -\                                                                  
       /                 \                                                                 
      /                   \                                                                
+--------------------++--------------------+                                               
| Connection Process || Connection Process |                                               
|                    ||                    |                                               
| +--------+         || +--------+         |                                               
| | socket |         || | socket |         |                                               
| +--------+         || +--------+         |                                               
+--------------------++--------------------+

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hairyhum

Hi. Thanks for contributing!

The architecture makes sense.

Left some comments. Mostly related to the address type implementation.
We're currently working to phase out and eventually deprecate this feature in favour of connection workers. This would simplify transport implementation and examples.

The way it should work is that you would create a connection worker like:
{:ok, client} = UDS.Client.create(uds_address)

And then send messages to this client address instead of the UDAddress:
Ockam.Router.route(%Ockam.Message{onward_route: [client, "echo"], payload: "HI"})

See Ockam.Transport.TCP.Client

Also added some notes about connection management.

Let us know if you have any questions about this approach or how to make ockam workers out of gen servers.

hairyhum · 2023-02-10T20:19:07Z

examples/elixir/get_started/06-secure-channel-over-two-uds-transport-hops-initiator.exs

+
+# Connect to a secure channel listener and perform a handshake.
+alias Ockam.Transport.UDSAddress
+r = [UDSAddress.new("/tmp/sock1"), "h1", UDSAddress.new("/tmp/sock2"), "secure_channel_listener"]


We're trying to steer away from using implicit connections expressed in specific address types and towards explicit connection workers.
I think we can simplify example by first creating a connection worker like {:ok, client} = UDS.Client.create("/tmp/sock1") and then sending messages through it.
That removes support for multi-hop thing and simplifies the example as it would only have 2 nodes.

Thanks @hairyhum, this is great feedback! I went back and did some more reading and implemented an Ockam.Transport.UDS.Client and used it in a Routing example, similar to how you specified it in your main comment. I still have to clean up the get_started examples and the UDSAddress.

hairyhum · 2023-02-10T20:20:47Z

implementations/elixir/ockam/ockam/lib/ockam/transport/uds/address.ex

@@ -0,0 +1,16 @@
+defmodule Ockam.Transport.UDSAddress do


As mentioned in other comment, we're trying to steer away from specific address types, so let's not add new ones.

hairyhum · 2023-02-10T20:21:17Z

implementations/elixir/ockam/ockam/lib/ockam/transport/uds.ex

+    Supervisor.init(children, strategy: :rest_for_one)
+  end
+
+  def handle_transport_message(message) do


If we don't use a special transport type, this becomes unnecessary.

hairyhum · 2023-02-10T20:22:06Z

implementations/elixir/ockam/ockam/lib/ockam/transport/uds.ex

+           pick_destination_and_set_onward_route(message),
+         {:ok, encoded_message} <- Wire.encode(message),
+         {:ok, socket} <-
+           :gen_tcp.connect({:local, destination}, 0, [:binary, active: true, reuseaddr: true]),


For connecting to a remote node, if we do that in the message handler, what happens with the connection?
Should we have some "client" worker to manage the connection in that case?

hairyhum · 2023-02-10T20:23:22Z

implementations/elixir/ockam/ockam/lib/ockam/transport/uds/connection.ex

+  end
+
+  @impl true
+  def handle_info({:tcp, socket, data}, %__MODULE__{socket: socket} = state) do


This module currently only supports TCP->Ockam messages.
How do we reply to those messages?

In other transport handler workers we were tracing the address of the worker in the message return route (see Ockam.Transport.TCP.Handler around line 70).

I see this is not yet a worker, this comment is to keep in mind when you make it a worker.

hairyhum · 2023-02-10T20:23:43Z

implementations/elixir/ockam/ockam/lib/ockam/transport/uds/connection_supervisor.ex

@@ -0,0 +1,23 @@
+defmodule Ockam.Transport.UDS.ConnectionSupervisor do


I like this approach.

hairyhum · 2023-02-10T20:24:40Z

implementations/elixir/ockam/ockam/lib/ockam/transport/uds/listener.ex

+  def run(path) do
+    case :gen_tcp.listen(0, [
+           :binary,
+           {:active, true},


If we listen in the active mode, does it mean that it's possible to get connection messages on the wrong process if there is some race condition between accept and change of controlling process?

Good point, perhaps one way to deal with this would be to start with passive or active once and switch it once the Connection child is up.

hairyhum · 2023-02-10T20:27:15Z

examples/elixir/get_started/06-secure-channel-over-two-uds-transport-hops-responder.exs

+alias Ockam.Transport.UDSAddress
+
+# Create a Echoer type worker at address "echoer".
+{:ok, _echoer} = Echoer.create(address: UDSAddress.new("/tmp/sock2"))


I understand it's WIP, but the address option we pass to the worker would be this worker address.
Passing transport addresses in this option is not going to work because transport addresses are handled differently. And I believe that wasn't intended behaviour in the first place.

hairyhum · 2023-02-16T17:18:48Z

implementations/elixir/ockam/ockam/lib/ockam/examples/routing/uds.ex

+    {:ok, hop} = Ockam.Transport.UDS.Client.create(path: "/tmp/client.sock")
+
+    Ockam.Router.route(%{
+      onward_route: [server_host_address, hop, "echoer"],


This route sends a message through server uds transport and then a "client.sock" uds transport and then to "echo".
Although that should probably work, it can be a bit confusing.
I think hop and "client.sock" can be removed to make a simpler example.

etorreborre · 2023-05-23T10:39:25Z

Hi @tzumby I can see it has been a while since this PR has been opened. Is there anything we can do to help you finish it?

tzumby · 2023-05-25T21:39:55Z

Hey @etorreborre, thanks for messaging, I would love to push this over the finish line, but I'm absolutely swamped with work. If this is blocking anything maybe it makes sense that I either close it or have someone else co-author this with me ?

etorreborre · 2023-05-26T07:30:52Z

@tzumby no worries this is not on the critical path at the moment but we will see if we can maybe find someone to help you out with this.

feat(elixit): Initial unix domain sockets implementation using gen_tcp

aeace20

tzumby force-pushed the tzumby/elixir-uds-transport branch from b413f2e to aeace20 Compare February 7, 2023 17:21

tzumby added 2 commits February 7, 2023 14:40

feat(elixir): Add examples for multi hop secure transport

f8f8014

feat(elixir): Clean up Connection process

a6ae254

hairyhum reviewed Feb 10, 2023

View reviewed changes

feat(elixir): Add UDS.Client worker and a routing example

71c1de6

hairyhum reviewed Feb 16, 2023

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aecepoglu mentioned this pull request Oct 23, 2023

Elixir: Support for unix domain socket transport #4042

Closed

nazmulidris mentioned this pull request Oct 24, 2023

Elixir: Provide support for unix domain socket transport #6755

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feat(elixir): add unix domain sockets transport and getting-started example #4220

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etorreborre commented May 26, 2023

		@@ -0,0 +1,23 @@
		defmodule Ockam.Transport.UDS.ConnectionSupervisor do

feat(elixir): add unix domain sockets transport and getting-started example #4220

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feat(elixir): add unix domain sockets transport and getting-started example #4220

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tzumby commented Feb 7, 2023 • edited Loading

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etorreborre commented May 23, 2023

tzumby commented May 25, 2023

etorreborre commented May 26, 2023

tzumby commented Feb 7, 2023 •

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tzumby Feb 15, 2023 •

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