Rootless Pings in Rust

Post by scottlamb » Tue, Dec 02, 2025, 3:14 PM UTC

antonvs wrote: post #59

scottlamb wrote: post #54

Earlier quoted context omitted.

> The issue is that the rust library apparently conflates datagram and UDP, when they're not the same thing. It comes down to these two lines (using full items paths for clarity): let socket = socket2::Socket::new(Domain::IPV4, Type::DGRAM, Some(Protocol::ICMPV4))?; let socket: std::net::UdpSocket = socket.into(); The latter is using this impl: https://docs.rs/socket2/0.6.1/socket2/struct.Socket.html#imp... Basically…

It may be memory safe but it's not using the type system to represent the domain very well. One could imagine a more type-friendly design in which we could write that first line as follows: let socket: Socket = Socket::new()?; Now, the specifics of socket types will be statically checked. Edit: I realized that the issue here is actually the conversion, and that UdpSocket on its own is actually a type-safe representat…

Post by knorker » Tue, Dec 02, 2025, 3:42 PM UTC

Quarrel wrote: post #46

messe wrote: post #25

> It turns out you can create a UDP socket with a protocol flag, which allows you to send the ping rootless This is wrong, despite the Rust library in question's naming convention. You're not creating a UDP socket. You're creating an IP (AF_INET), datagram socket (SOCK_DGRAM), using protocol ICMP (IPPROTO_ICMP). The issue is that the rust library apparently conflates datagram and UDP, when they're not the same thing.…

Thank you. I assumed this was what was happening, but conflating network layer protocols with transport layer ones isn't great. I'm surprised that pedantic zealots, like me in my youth, haven't risen up and flooded rust with issues over it way before this though.

    fn main() {
        let f = std::fs::File::open("/dev/null").unwrap();
        let f: std::os::fd::OwnedFd = f.into();
        let socket: std::net::UdpSocket = f.into();
    }

Post by antonvs » Tue, Dec 02, 2025, 3:47 PM UTC

scottlamb wrote: post #61

antonvs wrote: post #59

Earlier quoted context omitted.

It may be memory safe but it's not using the type system to represent the domain very well. One could imagine a more type-friendly design in which we could write that first line as follows: let socket: Socket = Socket::new()?; Now, the specifics of socket types will be statically checked. Edit: I realized that the issue here is actually the conversion, and that UdpSocket on its own is actually a type-safe representat…

One could, but one probably doesn't want to have separate types for TCP-over-IPv4 vs TCP-over-IPv6 for example, even if they accept/produce different forms of addresses. That'd force a lot of code bloat with monomorphization. So now one is making one's own enumeration which is different than the OS one and mapping between them, which can get into a mess of all the various protocols Linux and other OSs support, and I'…

Post by knorker » Tue, Dec 02, 2025, 3:59 PM UTC

antonvs wrote: post #59

scottlamb wrote: post #54

Earlier quoted context omitted.

> The issue is that the rust library apparently conflates datagram and UDP, when they're not the same thing. It comes down to these two lines (using full items paths for clarity): let socket = socket2::Socket::new(Domain::IPV4, Type::DGRAM, Some(Protocol::ICMPV4))?; let socket: std::net::UdpSocket = socket.into(); The latter is using this impl: https://docs.rs/socket2/0.6.1/socket2/struct.Socket.html#imp... Basically…

It may be memory safe but it's not using the type system to represent the domain very well. One could imagine a more type-friendly design in which we could write that first line as follows: let socket: Socket = Socket::new()?; Now, the specifics of socket types will be statically checked. Edit: I realized that the issue here is actually the conversion, and that UdpSocket on its own is actually a type-safe representat…

Post by pwdisswordfishy » Tue, Dec 02, 2025, 4:19 PM UTC

stavros wrote: post #27

vbezhenar wrote: post #21

Earlier quoted context omitted.

ICMP is just different protocol from UDP. There's field "Protocol" in IP packet. 0x01 = ICMP, 0x06 = TCP, 0x11 = UDP. I think that this article gets terminology wrong. It's not UDP socket that gets created here, but Datagram socket. Seems to be bad API naming in Rust library.

> It's not UDP socket that gets created here, but Datagram socket A datagram socket is a UDP socket, though. That's what the D stands for.