Stop beaconing if bcning null or absent

[emanuele-dedonatis]

Fix: Beaconing not stopped on reconnection when bcning field is absent or null

Problem

Once beaconing was started via router_config, it could not be stopped on subsequent reconnections. Two cases were broken:

1. "bcning": null — explicitly sending null had no effect; the gateway kept beaconing.
2. bcning field absent — omitting the field on reconnection left s2ctx->bcn untouched and the beacon timer kept running.

This was a problem for network servers that send router_config on every reconnection and rely on the absence of bcning to mean "no beaconing required".

Root Cause

In handle_router_config() (s2e.c):

• The J_bcning: null case just breaked without clearing any state.
• The end-of-function check only handled the start beaconing case (bcn.ctrl&0xF0 != 0). There was no else branch to stop beaconing when the new config carried no beacon frequencies.

Since bcn is a local variable initialized to zero, a missing or empty bcning field would always result in bcn.ctrl == 0, silently skipping the if block and leaving s2ctx->bcn and the beacon timer from the previous session intact.

Fix

1. Handle "bcning": null explicitly:

case J_bcning: {
    if( uj_null(D) ) {
        rt_clrTimer(&s2ctx->bcntimer);
        memset(&s2ctx->bcn, 0, sizeof(s2ctx->bcn));
        LOG(MOD_S2E|INFO, "Beaconing disabled (bcning: null)");
        break;
    }
    // ...
}

2. Stop beaconing when bcning is absent or carries no frequencies:

if( (bcn.ctrl&0xF0) != 0 ) {
    // start beaconing (unchanged)
    ...
} else if( (s2ctx->bcn.ctrl&0xF0) != 0 ) {
    // bcning absent or no frequencies — stop ongoing beaconing
    rt_clrTimer(&s2ctx->bcntimer);
    memset(&s2ctx->bcn, 0, sizeof(s2ctx->bcn));
    LOG(MOD_S2E|INFO, "Beaconing disabled (bcning field absent or no frequencies)");
}

Behaviour After Fix

router_config sent	Before	After
"bcning": { "freqs": [...] }	✅ Starts beaconing	✅ Starts beaconing
"bcning": null	❌ No effect	✅ Stops beaconing
bcning field absent	❌ Kept beaconing	✅ Stops beaconing
"bcning": { "freqs": [] }	❌ Kept beaconing	✅ Stops beaconing

Files Changed

• src/s2e.c