Issue: MDNS server initially sends probing packets to resolve naming confilicts with already registered service instances. In case of a conflict, instance name is altered and probing restarts. Original instance however wasnnot removed from the structure and upon service removal only one entry was removed and a dangling service might have been kept in the structure to bring about a crash.
Resolution: Keep only one instance of a service in the probing structure.
possible race condition: user task runs mdns_init, which enables pcbs while mdns-task already created could execute enable/disable of the same pcbs if an appropriate system event received
mnds_free() initiates stop and delete timer tasks, which after locking the mutex could lead to a dead lock in case timer task executed before deleting the task, as it would wait indefinitelly for unlocking the mutex. This condition is fixed by calling _mdns_stop_timer without locking the mutex, because there's no need to protect any data when stopping and deleting the timer task
Issue: mdns_service_add API allocates and queues an action to be processed in mdns task context; when allocation or queueing fails, allocated structure needs to be freed. Function _mdns_free_service did not only fee all the structures, but also updates packet data.
Resolution: Moved removal of packet data outside of _mdns_free_service function.
packets scheduled to transmit are pushed to action queue and removed from tx_queue_head structure, which is searched for all remaining services and while service is removed, then service questions/asnwers are also removed from this structure. This update fixes possible crash when packet is pushed to action queue, and when service is removed, its answers are removed from tx_queue_head, but not from action queue. this could lead to a crash when the packet is poped from action queue containing questions/answers to already removed (freed) service
Shortcircuit evaluation may cause skip of _mdns_strdup_check of any further question field, which after clear_rx_packet freed undefined memory.
Fixes https://ezredmine.espressif.cn:8765/issues/28465
mdns queries did not work properly when send imeadiately after set_hostname, which cuased reinit of pcb and therefore restarted probing, so search packets were blocked until probing finished
closes#2507, closes#2593
Allocation was happening later, causing possible use of stack variables
of caller function, which could be invalid.
Signed-off-by: Piyush Shah <piyush@espressif.com>
Send the Goodbye packet while removing an mDNS service as an "Authoritative" packet so
that the listeners remove the service from their records immediately.
* Change snprintf for strlcat does not complain w/gcc7.2.0 and it is safer, thanks @projectgus
* Use proper quotes for character literals
Merges https://github.com/espressif/esp-idf/pull/1163
Old behavior assumes message compressed when any of 2 most significant bits are set,
But in fact Message compressed only when both those bits are set to 1.
Also maximal label length should be 63 bytes.