Add Network Error Monitoring and Event Notification #415
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Previously, failures in set_multicast_if_v4/v6() were only logged at
DEBUG level and silently ignored, causing complete mDNS failure on
affected interfaces without any visible indication.
Example of trace log:
```
2026-01-15T09:11:18.270 TRACE mdns_sd::service_daemon: sending out probing of questions: [DnsQuestion { entry: DnsEntry { name: "6004X00003.local.", ty: ANY, class: 1, cache_flush: false } }, DnsQuestion { entry: DnsEntry { name: "Device 🎵🎵._connect._tcp.local.", ty: ANY, class: 1, cache_flush: false } }]
2026-01-15T09:11:18.270 TRACE mdns_sd::service_daemon: send query: 2 questions 0 answers 3 authorities 0 additional
2026-01-15T09:11:18.270 DEBUG mdns_sd::service_daemon: send_dns_outgoing: failed to set multicast interface for IPv4 192.168.64.61: Cannot assign requested address (os error 99)
2026-01-15T09:11:18.301 TRACE mdns_sd::service_daemon: sending out probing of questions: [DnsQuestion { entry: DnsEntry { name: "6004X00003.local.", ty: ANY, class: 1, cache_flush: false } }, DnsQuestion { entry: DnsEntry { name: "Device 🎵🎵._connect._tcp.local.", ty: ANY, class: 1, cache_flush: false } }]
2026-01-15T09:11:18.301 TRACE mdns_sd::service_daemon: send query: 2 questions 0 answers 3 authorities 0 additional
2026-01-15T09:11:18.302 TRACE mdns_sd::service_daemon: sent out 292 bytes on interface lo (idx 1) addr 127.0.0.1
2026-01-15T09:11:18.302 TRACE mdns_sd::service_daemon: event received with key Token(4)
```
This commits:
- Adds DaemonEvent::NetworkError variant for application monitoring
- Elevates critical network errors from DEBUG to ERROR log level
- Propagates monitor notifications through all network operations
- Ensures all multicast interface errors are captured and reported
Applications can now detect these errors and implement retry logic.
Author
|
Here is the full log file for more context, line 290 This commit allows the app to be aware of this issue, otherwise, this error is silently ignored. |
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Add Network Error Monitoring and Event Notification
Summary
This PR adds comprehensive monitoring and notification for critical network errors that occur during mDNS packet transmission. Previously, failures in
set_multicast_if_v4()andset_multicast_if_v6()were only logged at DEBUG level and silently ignored, preventing any mDNS traffic from being sent on affected interfaces without any visible indication to the application.Problem
When
set_multicast_if_v4()orset_multicast_if_v6()fails (commonly with "Cannot assign requested address" - OS error 99), the daemon would:This is a critical error that causes complete mDNS failure on affected interfaces, but was previously invisible to applications using the library.
Example Error Log
I don't have a pattern to reproduce it unfortunately.
Solution
1. New
DaemonEvent::NetworkErrorVariantAdded a new event type that applications can monitor:
2. Elevated Log Level
Changed critical network errors from DEBUG to ERROR level with clear "CRITICAL ERROR" prefix:
3. Automatic Monitor Notification
All network configuration errors now automatically notify monitors, allowing applications to:
4. Complete Monitoring Propagation
Refactored internal functions to accept and propagate
monitorsparameter:send_dns_outgoing_impl()- Now acceptsmonitorsparameterannounce_service_on_intf()- Now propagates monitors to implementationsend_dns_outgoing()- Now accepts and propagates monitorsSome(&mut self.monitors)where availableThis ensures all network errors are captured and reported, not just a subset.
Usage Example
Applications can now monitor for network errors: