cloudflare-internship-2020/internship-application-systems

Cloudflare Internship Application: Systems

What is it?

Please write a small Ping CLI application for MacOS or Linux. The CLI app should accept a hostname or an IP address as its argument, then send ICMP "echo requests" in a loop to the target while receiving "echo reply" messages. It should report loss and RTT times for each sent message.

Please choose from among these languages: C/C++/Go/Rust

Useful Links

• A Tour of Go
• The Rust Programming Language

Requirements

1. Use one of the specified languages

Please choose from among C/C++/Go/Rust. If you aren't familiar with these languages, you're not alone! Many engineers join Cloudflare without specific langauge experience. Please consult A Tour of Go or The Rust Programming Language.

2. Build a tool with a CLI interface

The tool should accept as a positional terminal argument a hostname or IP address.

3. Send ICMP "echo requests" in an infinite loop

As long as the program is running it should continue to emit requests with a periodic delay.

4. Report loss and RTT times for each message

Packet loss and latency should be reported as each message received.

Submitting your project

When submitting your project, you should prepare your code for upload to Greenhouse. The preferred method for doing this is to create a "ZIP archive" of your project folder: for more instructions on how to do this on Windows and Mac, see this guide.

Please provide the source code only, a compiled binary is not necessary.

Using Libraries

You may use libraries (both built-in and installed via package managers) and system calls as necessary. Please don't use the ping built-in application or a full library implementation of ping.

Extra Credit

1. Add support for both IPv4 and IPv6
2. Allow to set TTL as an argument and report the corresponding "time exceeded” ICMP messages
3. Any additional features listed in the ping man page or which you think would be valuable

internship-application-systems's Issues

Decoupling Sending and Receiving

From the task statement, it is unclear whether sending the ping and receiving the ping should happen sequentially (send -> wait -> receive -> send next ping -> wait -> receive next ping...) or concurrently. It seems that the Linux ping command adopts the concurrent paradigm (packets can be received out of order), while other similar programs/reimplementations use the sequential paradigm (likely for its simplicity). For this task, is there a preference on which paradigm we should implement?

Sorry if this is a bit unclear, since I am trying to be vague to not give away any hints, etc.

Use of External Libraries

I am very excited that Cloudflare is hosting this task for summer interns. However, I think there is an important aspect of this task that should be clarified: are external libraries (outside of the standard libraries that come with the languages) explicitly allowed? If so, how will they be bundled with our source code?

Thanks!

Regarding Resubmission of Source Code

Hi,

I just wanted to know if there is any way I can resubmit my solution?

Overview of Project

Hello,
I want to wrap my head around the scope before I start. If we chose C/C++, is the user simply going to type ./a.out hostname|IP-address?

And then the program stops sending echo requests when the user types in a command C signal? Then when it stops it prints the statistics.

Basically this program should behave exactly like the unix ping command?