Processing a received PUBCOMP after client reconnect crashes the session

[dergraf]

Expected behavior

A client dies, but it has unacked PUBREL frames. Once the client reconnects VerneMQ resends the PUBREL and expects a PUBCOMP. When VerneMQ processes the PUBCOMP it removes the PUBREL from the "waiting Acks".

Actual behaviour

A client dies, but it has unacked PUBREL frames. Once the client reconnects VerneMQ resends the PUBREL and expects a PUBCOMP. When VerneMQ processes the PUBCOMP the session crashes.

This case should be covered in https://github.com/erlio/vernemq/blob/master/apps/vmq_server/test/vmq_publish_SUITE.erl#L177, however the testcase doesn't check that the session is actually still alive after sending the PUBCOMP.

The Crash log:

2018-07-10 09:48:32 =CRASH REPORT====
  crasher:
    initial call: vmq_ranch:init/5
    pid: <0.3415.0>
    registered_name: []
    exception error: {{case_clause,<<98,2,0,1>>},[{vmq_mqtt_fsm,connected,2,[{file,"/home/graf/Projects/vernemq/_build/test/lib/vmq_server/src/vmq_mqtt_fsm.erl"},{line,350}]},{vmq_mqtt_fsm,in,3,[{file,"/home/graf/Projects/vernemq/_build/test/lib/vmq_server/src/vmq_mqtt_fsm.erl"},{line,168}]},{vmq_mqtt_fsm,data_in,3,[{file,"/home/graf/Projects/vernemq/_build/test/lib/vmq_server/src/vmq_mqtt_fsm.erl"},{line,142}]},{vmq_ranch,handle_message,2,[{file,"/home/graf/Projects/vernemq/_build/test/lib/vmq_server/src/vmq_ranch.erl"},{line,174}]},{vmq_ranch,loop_,1,[{file,"/home/graf/Projects/vernemq/_build/test/lib/vmq_server/src/vmq_ranch.erl"},{line,117}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,247}]}]}
    ancestors: [<0.3385.0>,<0.3384.0>,ranch_sup,<0.3125.0>]
    message_queue_len: 0
    messages: []
    links: [<0.3385.0>,#Port<0.332260>]
    dictionary: [{mqtt_pubrel_sent,#Ref<0.1645208890.790233092.75259>},{mqtt_publish_sent,#Ref<0.1645208890.790233092.75256>},{mqtt_connect_received,#Ref<0.1645208890.790233092.75240>},{max_msg_size,0},{bytes_sent,#Ref<0.1645208890.790233092.75239>},{bytes_received,#Ref<0.1645208890.790233092.75238>},{rand_seed,{#{jump => #Fun<rand.16.15449617>,max => 288230376151711743,next => #Fun<rand.15.15449617>,type => exsplus},[215213621333760556|442190220450265]}},{mqtt_connack_accepted_sent,#Ref<0.1645208890.790233092.75250>},{socket_open,#Ref<0.1645208890.790233092.75235>},{mqtt_pubcomp_received,#Ref<0.1645208890.790233092.75245>}]
    trap_exit: true
    status: running
    heap_size: 1598
    stack_size: 27
    reductions: 1627

[dergraf]

Fixed in PR #763