Port does not close client connection when the FIX session is terminated

[wbjohnston]

Steps to reproduce

1. Connect to matchbook on localhost:8080

2. Send a valid logon message.

   {
       "Header": {
           "BeginString": "FIX.4.2",
           "MsgType": "A",
           "SenderCompID": "wbj",
           "TargetCompID": "matchbook",
           "MsgSeqNum": 1,
           "SendingTime": "2021-03-16 21:58:53.521981634 UTC"
       },
       "Body": {},
       "Trailer": {}
   }

3. Send a message with an already used sequence number. In this case 1 has already been used

   {
       "Header": {
           "BeginString": "FIX.4.2",
           "MsgType": "D",
           "SenderCompID": "wbj",
           "TargetCompID": "matchbook",
           "MsgSeqNum": 1,
           "SendingTime": "2021-03-16 21:58:53.521981634 UTC"
       },
       "Body": {
           "ClOrdId": "foobar",
           "HandlInst": "3",
           "Price": 12.0,
           "Symbol": "ADBE",
           "Side": "1",
           "TransactTime": "2021-03-16 21:58:53.521981634 UTC",
           "OrdType": "2",
           "OrderQty": 100.0
       },
       "Trailer": {}
   }

4. Receive a Logout message

5. The connection will remain open

Log

ncat localhost 8080
{"Header": { "BeginString": "FIX.4.2", "MsgType": "A", "SenderCompID": "wbj", "TargetCompID": "matchbook", "MsgSeqNum": 1, "SendingTime": "2021-03-16 21:58:53.521981634 UTC" }, "Body": {}, "Trailer": {}}
{"Header":{"BeginString":"FIX.4.2","MsgType":"A","SenderCompID":"matchbook","TargetCompID":"wbj","MsgSeqNum":1,"SendingTime":"2021-03-16T21:58:53.521981634Z"},"Body":{},"Trailer":{}}{"Header": { "BeginString": "FIX.4.2", "MsgType": "D", "SenderCompID": "wbj", "TargetCompID": "matchbook", "MsgSeqNum": 2, "SendingTime": "2021-03-16 21:58:53.521981634 UTC" }, "Body": { "ClOrdId": "foobar", "HandlInst": "3", "Price": 12.0, "Symbol": "ADBE", "Side": "1", "TransactTime": "2021-03-16 21:58:53.521981634 UTC", "OrdType": "2", "OrderQty": 100.0}, "Trailer": {}}
{"Header":{"BeginString":"FIX.4.2","MsgType":"8","SenderCompID":"matchbook","TargetCompID":"wbj","MsgSeqNum":1,"SendingTime":"2021-03-18T22:07:16.016448572Z"},"Body":{"OrderID":"foobar","OrdStatus":"0","ExecID":"foobar","ExecTransType":"0","ExecType":"0","LeavesQty":100.0,"CumQty":0.0,"AvgPx":0.0,"Symbol":"ADBE","Side":"1","OrderQty":100.0},"Trailer":{}}{"Header": { "BeginString": "FIX.4.2", "MsgType": "D", "SenderCompID": "wbj", "TargetCompID": "matchbook", "MsgSeqNum": 2, "SendingTime": "2021-03-16 21:58:53.521981634 UTC" }, "Body": { "ClOrdId": "foobar", "HandlInst": "3", "Price": 12.0, "Symbol": "ADBE", "Side": "1", "TransactTime": "2021-03-16 21:58:53.521981634 UTC", "OrdType": "2", "OrderQty": 100.0}, "Trailer": {}}
{"Header":{"BeginString":"FIX.4.2","MsgType":"5","SenderCompID":"matchbook","TargetCompID":"matchbook","MsgSeqNum":1,"SendingTime":"2021-03-18T22:07:18.620860722Z"},"Body":{},"Trailer":{}}
^C

NOTE the above log contains me sending messages, and the responses. The connection didn't terminate until I used ctrl+c.