Everything about icmp
So. Serializing IPv4 packets. Easy? Well, not exactly.
IPv4 was annoying to parse, because we had 3-bit integers, and 13-bit integers, and who knows what else. Serializing it is going to be exactly the same.
In the last part, we've finally parsed some IPv4 packets. We even found a way to filter only IPv4 packets that contain ICMP packets.
Hello and welcome to Part 11 of this series, wherein we finally use some of the code I prototyped way back when I was planning this series.
Where are we standing?
Let's set aside our sup
project for a while.
Don't get me wrong - it's a perfectly fine project, and, were we simply rewriting "ping" for Windows in Rust, we could (almost) stop there.
Our ping API is simple, but it's also very limited:
pub fn ping(dest: ipv4::Addr) -> Result<(), String> // called as: ping(ipv4::Addr([8, 8, 8, 8])).unwrap();
We've just spent a lot of time abstracting over LoadLibrary, but we still have all the gory details of the Win32 ICMP API straight in our main.rs file! That won't do.
It's time to make sup
, our own take on ping
, use the Win32 APIs to send
an ICMP echo. Earlier we discovered that Windows's ping.exe
used
IcmpSendEcho2Ex
. But for our purposes, the simpler IcmpSendEcho
will do
just fine.
So, how does ping.exe
actually send a ping? It seems unrealistic that
ping.exe
itself implements all the protocols involved in sending a ping.
So it must be calling some sort of library. Also, since it ends up
talking to the outside world via a NIC (network interface controller),
the kernel is probably involved at some point.