edsiper / libssh2_channels

Test case for a LibSSH2 channels problem

LibSSH2 Port Forwarding Test case

The program connects to the SSH server running at localhost:22 and after authentication it request to forward the localhost:9000 TCP port over the SSH tunnel.

For testing purposes make sure you edit fwd-client.c and modify the username and place your certificates id_rsa.prv and id_rsa.pub.

How it works

After the client runs and establish a session, it waits for events on the socket connected to the server. When a client connects, it reads some data and write back some HTTP response, it can be tested with curl as follows:

$ curl -i http://localhost:9000
HTTP/1.0 200 OK
Connection: close
Content-Length: 10

abcd efgh

One connection works.

The problem

If this code faced multiple requests (multiple channels) for some reason it fails to handle channels data properly. This can be tested with Apache Benchmark:

$ ab -n 10 -c 2 http://localhost:9000/
This is ApacheBench, Version 2.3 <$Revision: 1528965 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done


Server Software:
Server Hostname:        localhost
Server Port:            9000

Document Path:          /
Document Length:        0 bytes

Concurrency Level:      2
Time taken for tests:   0.046 seconds
Complete requests:      10
Failed requests:        9
   (Connect: 0, Receive: 0, Length: 5, Exceptions: 4)
   Total transferred:      340 bytes
   HTML transferred:       50 bytes
   Requests per second:    215.70 [#/sec] (mean)
   Time per request:       9.272 [ms] (mean)
   Time per request:       4.636 [ms] (mean, across all concurrent requests)
   Transfer rate:          7.16 [Kbytes/sec] received
...

Allmost all connections failed, why ?...