LNet Memory Leak
lazarus / 38-Networking and Web Programming

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ttomas · 2012-12-12 13:12

I stress test LNet http server with DDoS attack tool LOIC
http://sourceforge.net/projects/loic/
Without DDoS attack there is no memory leak in http server.
With LOIC attack with 100 threads and when failed packets start to
increase we have 1024 bytes leak on every failed request. Memory leak
is from lnet.pas unit

Code: [Select]procedure TLTcp.AcceptAction(aSocket: TLHandle);
var
  Tmp: TLSocket;
begin
  Tmp := InitSocket(SocketClass.Create);  <<<<
TLSocket is allocated but never free.
This is not only http server problem, TCPServer is also effected.
After and in time of attack server work without problems with browser,
but memory increase and with long time attack we will have out of
memory.
I attach small demo project for testing.
Windows 7 64b and 32b, I use Lazarus 1.1 CodeTyphon 3.10, LNet source
is same with svn trunk.

I open in bug tracker
http://mantis.freepascal.org/view.php?id=23475

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Almindor · 2012-12-12 16:44

Thanks, I think it's a soft-disconnect problem when the other side
doesn't follow protocol. I'll have to reproduce and see what can be
done.

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ttomas · 2012-12-13 09:09

Other side protocol of communication is OK.
Memory leak can be reproduced also with Apache benchmark tool.
With AB there is no failed request.
Also performance is not so good for async server 24.99 req/s.

ab -n 100 -c 10 http://127.0.0.1:8088/index.html

This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd,
http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 127.0.0.1 (be patient).....done


Server Software:
Server Hostname:        127.0.0.1
Server Port:            8088

Document Path:          /index.html
Document Length:        11 bytes

Concurrency Level:      10
Time taken for tests:   4.002 seconds
Complete requests:      100
Failed requests:        0
Write errors:           0
Total transferred:      17700 bytes
HTML transferred:       1100 bytes
Requests per second:    24.99 [#/sec] (mean)
Time per request:       400.223 [ms] (mean)
Time per request:       40.022 [ms] (mean, across all concurrent
requests)
Transfer rate:          4.32 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0   40 135.5      0     497
Processing:     0  360 224.1    499     500
Waiting:        0  319 239.4    497     500
Total:          1  400 199.6    499     501

Percentage of the requests served within a certain time (ms)
  50%    499
  66%    499
  75%    499
  80%    499
  90%    500
  95%    500
  98%    500
  99%    501
 100%    501 (longest request)

With Keep Alive no memory leak
ab -k -n 100 -c 10 http://127.0.0.1:8088/index.html
~3000 req/sec

ab -k -n 1000 -c 100 http://127.0.0.1:8088/index.html
Crash the server
External SIGSEGV
In file lhttp.pp at line 1450
FCurrentOutput:=FCurrentOutput.FNext;