libwebsockets/minimal-examples-lowlevel/secure-streams/minimal-secure-streams-smd

lws minimal secure streams SMD

This application creates a Secure Stream link to LWS SMD, System Message Distribution.

The SS is able to receive system messages matching a specified class filter, and issue system messages also using SS payload semantics.

Both a direct api lws_smd participant and an SS based one are instantiated. They both filter on system messages.

When the Secure Stream is created, it asks to send using normal the SS api. In the SS tx callback, it prepares a header and then send a NETWORK class message.

Numbers of messages received each way and sent is compared after 2s and the test exits with a success or a fail.

Building and testing

Build with

-DLWS_WITH_SECURE_STREAMS=1 -DLWS_WITH_SECURE_STREAMS_PROXY_API=1 -DLWS_WITH_MINIMAL_EXAMPLES=1

The run ./bin/lws-minimal-secure-streams-smd alone (local SS and direct SMD tests) and after run ./bin/lws-minimal-secure-streams-proxy in one console and ./bin-lws-minimal-secure-streams-smd-client in the other (SS proxy tests)

What's going on in the -client test

The -client build version contains the test logic as usual, but outsources the policy and smd_ server part to the Secure Streams Proxy.

• start lws-minimal-secure-streams-proxy first

• start lws-minimal-secure-streams-smd-client

1. When the client starts, we waits to hear the client state is OPERATIONAL in a direct smd participant callback. When it is, he creates a Secure Stream of streamtype "_lws_smd", creating a local SS handle.

2. The SS creation request is proxied to the SS proxy process over Unix Domain Sockets. There it creates a Secure Stream object proxyside, and registers as an SMD participant... this smd-related behaviour is tied to the special streamtype name "_lws_smd". The SMD registration uses a class mask passed to the proxy in the tx credit field of the serialization.

3. SMD messages that pass the class mask filter are proxied back to the client over the connection.

4. SMD messages created at the client are passed to the proxy and added to the proxy's SMD queue, if the same connection's class mask accepts the message then it will be proxied back to the client same as other messages.

The minimal example produces a variety of messages on the SS link, including CPD detect trigger. The SS link is set up to only accept messages of classes LWSSMDCL_SYSTEM_STATE and LWSSMDCL_NETWORK, INTERACTION type messages are not accepted.

multi via proxy

If the -client version is run with --multi, it spawns four worker processes which send and confirm SMD messages between each other via the SS proxy.

build

 $ cmake . && make

usage

Commandline option	Meaning
-d	Debug verbosity in decimal, eg, -d15
--multi	Fork four worker processes that send and check messages to each other over sspc proxy

$ ./bin/lws-minimal-secure-streams-smd -d 1151
[2020/06/18 21:44:54:5148] U: LWS Secure Streams SMD test client [-d<verb>]
[2020/06/18 21:44:54:5601] I: Initial logging level 1151
[2020/06/18 21:44:54:5605] I: Libwebsockets version: 4.0.99-v4.0.0-174-ga8a2eb954 v4.0.0-174-ga8a2eb954
[2020/06/18 21:44:54:5607] I: IPV6 not compiled in
...
[2020/06/18 21:44:54:7906] D: _lws_state_transition: system: changed 11 'AUTH2' -> 12 'OPERATIONAL'
[2020/06/18 21:44:54:7906] D: _realloc: size 81: lws_smd_msg_alloc
[2020/06/18 21:44:54:7907] I: lws_cancel_service
[2020/06/18 21:44:54:7912] I: lws_state_transition_steps: CONTEXT_CREATED -> OPERATIONAL
[2020/06/18 21:44:54:7919] N: myss_tx: sending SS smd
[2020/06/18 21:44:54:7940] D: _realloc: size 84: lws_smd_msg_alloc
[2020/06/18 21:44:54:7944] I: lws_cancel_service
[2020/06/18 21:44:54:7966] D: direct_smd_cb: class: 0x2, ts: 3139600721554
[2020/06/18 21:44:54:7972] D: 
[2020/06/18 21:44:54:7990] D: 0000: 7B 22 73 74 61 74 65 22 3A 22 49 4E 49 54 49 41    {"state":"INITIA
[2020/06/18 21:44:54:7998] D: 0010: 4C 49 5A 45 44 22 7D                               LIZED"}         
[2020/06/18 21:44:54:8001] D: 
[2020/06/18 21:44:54:8016] I: myss_rx: len 39, flags: 3
[2020/06/18 21:44:54:8018] I: 
[2020/06/18 21:44:54:8021] I: 0000: 00 00 00 00 00 00 00 02 00 00 02 DA FE C9 26 92    ..............&.
[2020/06/18 21:44:54:8022] I: 0010: 7B 22 73 74 61 74 65 22 3A 22 49 4E 49 54 49 41    {"state":"INITIA
[2020/06/18 21:44:54:8023] I: 0020: 4C 49 5A 45 44 22 7D                               LIZED"}         
[2020/06/18 21:44:54:8023] I: 
[2020/06/18 21:44:54:8029] D: direct_smd_cb: class: 0x2, ts: 3139600724243
[2020/06/18 21:44:54:8029] D: 
[2020/06/18 21:44:54:8030] D: 0000: 7B 22 73 74 61 74 65 22 3A 22 49 46 41 43 45 5F    {"state":"IFACE_
[2020/06/18 21:44:54:8031] D: 0010: 43 4F 4C 44 50 4C 55 47 22 7D                      COLDPLUG"}      
[2020/06/18 21:44:54:8032] D: 
...
[2020/06/18 21:44:54:8112] D: direct_smd_cb: class: 0x4, ts: 3139600732952
[2020/06/18 21:44:54:8112] D: 
[2020/06/18 21:44:54:8114] D: 0000: 7B 22 73 6F 6D 74 68 69 6E 67 22 3A 22 6E 6F 74    {"somthing":"not
[2020/06/18 21:44:54:8115] D: 0010: 73 65 65 6E 62 79 73 73 72 78 22 7D                seenbyssrx"}    
[2020/06/18 21:44:54:8115] D: 
[2020/06/18 21:44:57:5823] I: 11 12 1
[2020/06/18 21:44:57:5838] I: lws_context_destroy: ctx 0x4f61db0
[2020/06/18 21:44:57:5849] D: _lws_state_transition: system: changed 12 'OPERATIONAL' -> 13 'POLICY_INVALID'
[2020/06/18 21:44:57:5851] D: _realloc: size 84: lws_smd_msg_alloc
[2020/06/18 21:44:57:5853] I: lws_cancel_service
[2020/06/18 21:44:57:5871] I: lws_destroy_event_pipe
[2020/06/18 21:44:57:5906] I: lws_pt_destroy: pt destroyed
[2020/06/18 21:44:57:5913] I: lws_context_destroy2: ctx 0x4f61db0
[2020/06/18 21:44:57:5936] D: lwsac_free: head (nil)
[2020/06/18 21:44:57:5947] D: 0x455970: post vh listl
[2020/06/18 21:44:57:5950] D: 0x455970: post pdl
[2020/06/18 21:44:57:5961] D: 0x455970: baggage
[2020/06/18 21:44:57:5968] D: 0x455970: post dc2
[2020/06/18 21:44:57:6010] D: lws_context_destroy3: ctx 0x4f61db0 freed
[2020/06/18 21:44:57:6014] U: Completed: OK