diff options
Diffstat (limited to 'hook-plugin/README.md')
| -rw-r--r-- | hook-plugin/README.md | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/hook-plugin/README.md b/hook-plugin/README.md new file mode 100644 index 0000000..0472c7b --- /dev/null +++ b/hook-plugin/README.md @@ -0,0 +1,77 @@ +Alsa-Hook-Plugin + +Object: Provide a Hook on Alsa PCM to check permission again AGL Advance Audio Agent +Status: Release Candidate +Author: Fulup Ar Foll fulup@iot.bzh +Date : August-2017 + +Functionalities: + - Execute a set of websocket RPC request again AGL binders to allow/deny access + - Keep websocket open in an idepandant thread on order to monitor event receive from AGL audio agent + +Installation + - Alsaplugins are typically search in /usr/share/alsa-lib. Nevertheless a full path might be given + - This plugin implement a hook on a slave PCM. Typically this slave PCM is a dedicated virtual channel (eg: navigation, emergency,...) + - Config should be place in ~/.asoundrc (see config sample in PROJECT_ROOT/conf.d/alsa) + +Test + - Install a full .asoundrc from conf.d/project/alsa.d + - speaker-test -DMyNavigationHook -c2 -twav + +Config +``` +# Define sharelib location and entry point +# ----------------------------------------- +pcm_hook_type.MyHookPlugin { + install "AlsaInstallHook" + lib "/home/fulup/Workspace/AGL-AppFW/audio-bindings-dev/build/Alsa-Plugin/Alsa-Hook-Callback/alsa_hook_cb.so" +} + +# Create PCM HOOK with corresponding request calls to AGL Audio Agent +# -------------------------------------------------------------------- +pcm.MyNavigationHook { + type hooks + slave.pcm "MyMixerPCM" + + # Defined used hook sharelib and provide arguments/config to install func + hooks.0 { + type "MyHookPlugin" + hook_args { + verbose true # print few log messages (default false); + + # Every Call should return OK in order PCM to open (default timeout 100ms) + uri "ws://localhost:1234/api?token='audio-agent-token'" + request { + # Request authorisation to write on navigation + navigation-ctl { + api "pol4a" + request "navigation-role" + release "navigation-role" + args "{'uid':'alsa-hook-navigation'}" + } + # subscribe to Audio Agent Event map them to signal + subscribe-evt { + api "pol4a" + verb "subscribe" + } + } + # map event reception to self generated signal + event { + pause 30 + resume 31 + stop 3 + } + } + } +} + +``` + +NOTE: + +* Hook plugin is loaded by Alsa libasound within player context. It inherits client process attributes, as UID/GID or +the SMACK label on AGL. This smack label is tested by AGL security framework when requested a call on the audio-agent binder. +As a result the call will only succeed it the permission attached the application in Cynara matches. + +* Hook plugin keep a connection with the Audio-Agent until PCM is closed by the application. This connection allow the +Audio-Agent to send events. eg: pause, quit, mute, ...
\ No newline at end of file |