System hang when connecting to client that doesn't exist.

[videojedi]

Hi,
Firstly, many thanks for your hardwork, it's really helping me with a project.

However, I'm a little stuck with a client connection to a server that isn't there. My teensy just hangs with the following message

Assertion "tcp_input: pcb->next != pcb (before cache)" failed at line 269 in C:\Users\admin\Documents\Arduino\libraries\QNEthernet\src\lwip\tcp_in.c

I'm just just initiating the connection with

if (client.connect(setupIP.rtrIPaddr, setupIP.rtrPort)) { blah } else { Serial.println("connection failed!"); }

Even the watchdog, is unable to recover the system hang.

Any thoughts greatly appreciated..

[ssilverman]

Thank you for the report. I will look when I have a chance. May I request a minimal full program that can reproduce this issue?

[ssilverman]

Also, would you mind creating an issue instead?

[videojedi]

I can of course, but there is a very good chance it's not an issue, and just my coding. :)

[ssilverman]

While it may have something to do with your coding, even if the coding is incorrect, it still means my library can expose an assert-level condition, which is a problem. I’ll have a look at your code…

[ssilverman]

I tried duplicating the error, but could not. I tried connecting to several valid addresses, local and global, several addresses I know can’t connect, local and global, then repeated all the tests without first calling Ethernet.begin(). I connected to port 80 and did a rudimentary HTTP connection. All my results were expected and I didn’t see any lwip asserts.

Are you, by any chance, trying to use the library in a multithreaded context? QNEthernet isn’t thread-safe.

I’ll need some code that generates the issue.

[videojedi]

I'm just trying to unpick my code, so I can send you something useful. (Also tidy it up :))

The teensy is hosting a webpage (EthernetWebServer.h) and is using Websockets (WebSockets2_Generic.h) to communicate between the browser and Teensy. Then I'm using a client connection to another piece of hardware. It all works amazingly well, until I use the web gui to change the IP address of the hardware I'm connecting to that doesn't exist. The crash seems to co-incide with a failed connection to hardware and a web page refresh or websocket update request.

Thanks for checking.

[videojedi]

Apologies, I've stripped out as much as I can, but leaving the barebones of the web gui. If you comment out line 157, then the webpage should load and you can enter the IP address of target device.

//comment following line to allow web gui to run again after crash PollHardware();

https://github.com/videojedi/js3debug.git

[ssilverman]

Thanks! I’ll have a look when I can.

[ssilverman]

I just pushed some changes that may fix the issue, specifically commit 7724fbe. See the latest master.

[ssilverman]

See also this commit: b69228f

[ssilverman]

Closing for now. Please reopen if you're still seeing this.