program blocked when tcp client connection to a tcp server failed

[roboticanyair]

Hi.
first of all - great work. the library is easy to use and understand.

When i try to connect to a tcp server that does not exist, the program get stuck after "Connection failed to the host" message is printed.
to reproduce that I ran the tcp-client.cpp example, I added print inside the while loop. It never gets printed.

while (input != "exit")
    {
        std::cout << "loop" << std::endl;
    
        tcpSocket.Send(input);
        getline(cin, input);
    }

[eminfedar]

Hi, did you remove the getline() above the loop?

    string input;
    getline(cin, input); // <---------------------- This blocks before entering the while loop.
    while (input != "exit")
    {
        tcpSocket.Send(input);
        getline(cin, input);
    }

[roboticanyair]

oops. my bad...

but it still happens in my code.
I have a timer that timer runs once every second. in the callback of the timer I'm trying to connect to the server each time.
when the connection succeeds - a message is printed and the timer is canceled. if it fails to connect to the server a message should be printed and another connection attempt should occur when the timer is being fired.
to verify that the program hangs, I created a second timer that runs every seconds and only prints the following message:
"another callback"
I have added a print in the beginning of the connecting timer callback, the prints "callback" and the current unix time in seconds.

this is the code inside the timer's callback:

std::cout.setf(std::ios::fixed);
std::cout << "callback " << std::setprecision(0)  << base_node_->now().seconds() << std::endl;;
command_client_.Connect(cell_address_, command_client_port_, [&] {
                                std::cout << "Connected to cell " << name_ << " server successfully." << std::endl;
        
                                connecting_timer_->cancel();
        
                            },
                            [&](int errorCode, const std::string &errorMessage) {
                                // CONNECTION FAILED
                                std::cout << "failed to connect to server : error " <<
                                          std::to_string(errorCode) << " : " << errorMessage << std::endl;
        
        
                            });

the output is:

callback 1613910931
failed to connect to server : error 110 : Connection failed to the host.
callback 1613911061
failed to connect to server : error 110 : Connection failed to the host.
callback 1613911192
failed to connect to server : error 110 : Connection failed to the host.
callback 1613911323
failed to connect to server : error 110 : Connection failed to the host.
callback 1613911454
failed to connect to server : error 110 : Connection failed to the host.
callback 1613911586
failed to connect to server : error 110 : Connection failed to the host.
callback 1613911717

it always hangs for 131 seconds (ish) and the callback of the second timer is never being called.
If i remove the part of the connection from the callback, it runs as it should and prints the "callback" message every second and "another callback" is printed every 2 seconds.

when there is listening server - every thing is OK.

when I run it in debug mode it's clear the it hangs inside the Connect function.

again, thanks for the hard work!

[eminfedar]

It is probably about "Connection Timeout". It is waiting for timeout when there is no server to reach.

I have added tcpSocket.setTimeout(secs) method and pushed today. (537d4d4)

Can you pull the project and try it again with setting a timeout value?

Example:

// Set timeout seconds:
tcpSocket.setTimeout(1);

// Then try to connect:
tcpSocket.Connect(...);

[roboticanyair]

It looks like the problem is solved! thanks a lot!