mdns_search_once_t::lock is used to synchronize tasks (taken by one
task and given by the other) so it should not be a mutex.
Convert to semaphore, and rename to indicate its purpose.
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
when running a query for a single txt, result entries were not created and attached to result structure. this issue was introduced when fixing memory leak in txt structure, which worked correctly for PTR queries, but caused trouble for TXT query.
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.
