ft_ping

Re create the ping command line in C (with some limitations).

usage

./sudo ft_ping <options> <destination>

Now supports Docker!

• run docker-compose run --rm --build ping
• Inside the container, run make then you can use ./ft_ping <options> <destination>

Notes

You can check which option is implemented using the -h option, the ones marked as "TODO" are obviously not done.

Also, my parsing sucks and is held by ducktape and glue don't judge it, everything else is usable.

Tips

• You should really use Wireshark to test and see how packets are sent and why yours might not check all the requirements to get a packet back.
• Use alarm() as a good way to wait for x amount of seconds consistently
• Don't overthink your headers. You could do it as I deal and only deal with the ICMP header using the struct icmphdr (kernel should handle the IPV4 header on its own). You can also create your own packet and handle the headers manually if you wish to do so.
• Since you cannot use any FD or socket handling, you can only wait and receive, also you cannot use fcntl() so use your own way of testing the socket.
• Last one: if you have issues receiving packets, USE WIRESHARK and check for checksum errors, if it's the case, read the universal man about the checksum part.

Known issues

• Not displaying the same amount of reiceved bytes as the mordern ping since the later one uses a timestamp field in the icmp header.
• Total exec time couldn't be done with gettimeofday() since the function should never be used to calculate these kind of things (here's a better explanation as of why).
• I'm not checking for receive specific error such as errors described in the packet sent back to you, it's not asked but I'll do it for traceroute.
• I don't do any reverse DNS lookup.
• I don't handle IPV6 (I used this project as an intro and aim to do a deeper work with the following project).

The end

I hope it can help some of you out, I know it sucks being post CC without any teammates to work with and I wish you can use this repo in some way to help you find things you were struggling with or anything. Much love.