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> I would assume you would do it in Rust just like you would in C. Where's the hang up? Why assume? If you know it can be done, why wouldn't you provide a poin

> I would assume you would do it in Rust just like you would in C. Where's the hang up? Why assume? If you know it can be done, why wouldn't you provide a pointer to an example? I've done my Google searching and can't find one. There are endless examples of this for C online, I'm just stating that with a cursory search I couldn't find one for Rust. The hang up is clearly at my end, I'm currently time poor, so now is not a good time for me to be learning a new language where I can't find good examples for what I'd use it for. Admittedly I need to start at "Hello World" with Rust anyway before I get as far as crafting raw UDP packets. The point I'm getting at is if I didn't know how to program in either C or Rust, I'd pick C for this problem right now because there are clear examples. That's all.

burntsushi 7y ago
If you don't know how to do it because you don't know Rust, then fine, that's reasonable. (Albeit a strange criticism to lodge from my perspective.) Otherwise, I would "assume" that you need to use libc bindings over ffi to use whatever udp APIs you would normally use from C. This is how Rust's standard library implements the higher level udp APIs for example: https://doc.rust-lang.org/std/net/struct.UdpSocket.html https://doc.rust-lang.org/std/net/struct.UdpSocket.html But I used a question mark also because this is not something I've done before, so I can't share an example. I wasn't being adversarial. Even my suggestion above could be wrong. That is, I don't understand the essential difficulty here. Perhaps someone else can chime in.
- nineteen999 7y ago
  Sorry, not to be rude but in this case is sounds like you don't understand the problem domain. Perhaps I should have just said "UDP spoofing". There is a huge difference between creating a generic UDP endpoint like the code you have shown, and crafting a raw UDP socket, where the source IP address is "spoofed", and UDP checksums generated to ensure that the packet looks like a valid UDP packet so that the intermediate network infrastructure like routers, switches and firewalls will pass the forged packet rather than discarding it. The latter requires quite a bit of extra code. A good example is here: https://www.binarytides.com/raw-udp-sockets-c-linux/ https://www.binarytides.com/raw-udp-sockets-c-linux/ and last time I looked (month or so ago?) I could not find an equivalent example for Rust. It may be out there but I was unable to locate it. I'm not asking you to do my homework for me, just stating that learning what I need to know in Rust to do the above would take more time than I have available right now. That's not to say I won't figure it out in the future when I have more time. > If you don't know how to do it because you don't know Rust, then fine, that's reasonable. (Albeit a strange criticism to lodge from my perspective.) It's not a criticism of the language; what I'm asking may be very possible, I don't know yet. I just know that finding C examples is trivial, Rust examples not so much, so when I had a need for this kind of code recently, I turned to the language where I know it can be done and I could easily find examples.
  - woah 7y ago
    The specific task is so obscure, that only a language as widespread as C would have an example online for it. So people are confused when you name this as a criteria for selecting a language, since it’s a criteria that most likely only C can satisfy. Then someone jumped to the conclusion that you were actually saying that Rust doesn’t have enough low level kernel APIs because that would make sense.
    - nineteen999 7y ago
      > The specific task is so obscure, that only a language as widespread as C would have an example online for it. Well you could do it in Python I suppose - here's someone mentioning a solution using scapy, although it likely wouldn't work too well for my particular case due to Python performance. https://stackoverflow.com/questions/51311741/generating-a-spoofed-udp-packet-in-python https://stackoverflow.com/questions/51311741/generating-a-sp... > So people are confused when you name this as a criteria for selecting a language, since it’s a criteria that most likely only C can satisfy Rust is intended to be a replacement for C and C++, no? Eventually it will need to be able to do things like this if it is to be effective in that role. It's OK in my mind if it is not mature enough to do these kind of tasks yet, or if it can but I can't find a good reference yet. I wanted to use it for this task, but I selected C instead since it was easy to do that way and I didn't have a lot of time. Not holding it against Rust, it's a much younger language. > Then someone jumped to the conclusion that you were actually saying that Rust doesn’t have enough low level kernel APIs because that would make sense. I am almost completely certain I don't understand this sentence the way it is phrased.
      - woah 7y ago
        Example code (for ARP though): https://github.com/libpnet/libpnet/blob/master/examples/arp_packet.rs https://github.com/libpnet/libpnet/blob/master/examples/arp_... Documentation: https://docs.rs/pnet/0.22.0/pnet/packet/udp/struct.MutableUdpPacket.html https://docs.rs/pnet/0.22.0/pnet/packet/udp/struct.MutableUd...
        7y ago
- nineteen999 7y ago
  My apologies - I don't mean to come off as adversarial either. And as I clarified in my other message, I should have just said UDP spoofing, so I probably contributed to the confusion. > I would "assume" that you need to use libc bindings over ffi I wonder about whether that is even necessary. socket() and sendto() are basically C library wrappers around system calls for the most part. Surely the Rust standard library already has equivalent wrappers, or will someday. There's no real reason I can think of that I'd need to FFI into C unless there is some limitation of the current Rust standard library.
  - burntsushi 7y ago
    No worries. You can use libc::syscall to make syscalls in the normal way, and that's technically ffi. Otherwise, to do raw syscalls, AFAIK you need to write some Assembly to do it. Running an assembler and linking it into a Rust program is pretty straight-forward. It would be nicer if one could use inline assembly (and let the compiler handle it for you), but that hasn't been stabilized yet. The topic of whether to build a Rust standard library without libc is definitely one that has gotten some attention, and some folks have made some progress on that front, but AFAIK there is no serious ongoing project or effort that attempts this. Some folks definitely desire it though, at least for Linux. (In other platforms, like macOS and Windows, raw syscalls aren't a stable interface, so you kind of need to use the system libraries.)

burntsushi 7y ago

If you don't know how to do it because you don't know Rust, then fine, that's reasonable. (Albeit a strange criticism to lodge from my perspective.) Otherwise, I would "assume" that you need to use libc bindings over ffi to use whatever udp APIs you would normally use from C. This is how Rust's standard library implements the higher level udp APIs for example: https://doc.rust-lang.org/std/net/struct.UdpSocket.html https://doc.rust-lang.org/std/net/struct.UdpSocket.html But I used a question mark also because this is not something I've done before, so I can't share an example. I wasn't being adversarial. Even my suggestion above could be wrong. That is, I don't understand the essential difficulty here. Perhaps someone else can chime in.

nineteen999 7y ago
Sorry, not to be rude but in this case is sounds like you don't understand the problem domain. Perhaps I should have just said "UDP spoofing". There is a huge difference between creating a generic UDP endpoint like the code you have shown, and crafting a raw UDP socket, where the source IP address is "spoofed", and UDP checksums generated to ensure that the packet looks like a valid UDP packet so that the intermediate network infrastructure like routers, switches and firewalls will pass the forged packet rather than discarding it. The latter requires quite a bit of extra code. A good example is here: https://www.binarytides.com/raw-udp-sockets-c-linux/ https://www.binarytides.com/raw-udp-sockets-c-linux/ and last time I looked (month or so ago?) I could not find an equivalent example for Rust. It may be out there but I was unable to locate it. I'm not asking you to do my homework for me, just stating that learning what I need to know in Rust to do the above would take more time than I have available right now. That's not to say I won't figure it out in the future when I have more time. > If you don't know how to do it because you don't know Rust, then fine, that's reasonable. (Albeit a strange criticism to lodge from my perspective.) It's not a criticism of the language; what I'm asking may be very possible, I don't know yet. I just know that finding C examples is trivial, Rust examples not so much, so when I had a need for this kind of code recently, I turned to the language where I know it can be done and I could easily find examples.
- woah 7y ago
  The specific task is so obscure, that only a language as widespread as C would have an example online for it. So people are confused when you name this as a criteria for selecting a language, since it’s a criteria that most likely only C can satisfy. Then someone jumped to the conclusion that you were actually saying that Rust doesn’t have enough low level kernel APIs because that would make sense.
  - nineteen999 7y ago
    > The specific task is so obscure, that only a language as widespread as C would have an example online for it. Well you could do it in Python I suppose - here's someone mentioning a solution using scapy, although it likely wouldn't work too well for my particular case due to Python performance. https://stackoverflow.com/questions/51311741/generating-a-spoofed-udp-packet-in-python https://stackoverflow.com/questions/51311741/generating-a-sp... > So people are confused when you name this as a criteria for selecting a language, since it’s a criteria that most likely only C can satisfy Rust is intended to be a replacement for C and C++, no? Eventually it will need to be able to do things like this if it is to be effective in that role. It's OK in my mind if it is not mature enough to do these kind of tasks yet, or if it can but I can't find a good reference yet. I wanted to use it for this task, but I selected C instead since it was easy to do that way and I didn't have a lot of time. Not holding it against Rust, it's a much younger language. > Then someone jumped to the conclusion that you were actually saying that Rust doesn’t have enough low level kernel APIs because that would make sense. I am almost completely certain I don't understand this sentence the way it is phrased.
    - woah 7y ago
      Example code (for ARP though): https://github.com/libpnet/libpnet/blob/master/examples/arp_packet.rs https://github.com/libpnet/libpnet/blob/master/examples/arp_... Documentation: https://docs.rs/pnet/0.22.0/pnet/packet/udp/struct.MutableUdpPacket.html https://docs.rs/pnet/0.22.0/pnet/packet/udp/struct.MutableUd...
      - 7y ago
nineteen999 7y ago
My apologies - I don't mean to come off as adversarial either. And as I clarified in my other message, I should have just said UDP spoofing, so I probably contributed to the confusion. > I would "assume" that you need to use libc bindings over ffi I wonder about whether that is even necessary. socket() and sendto() are basically C library wrappers around system calls for the most part. Surely the Rust standard library already has equivalent wrappers, or will someday. There's no real reason I can think of that I'd need to FFI into C unless there is some limitation of the current Rust standard library.
- burntsushi 7y ago
  No worries. You can use libc::syscall to make syscalls in the normal way, and that's technically ffi. Otherwise, to do raw syscalls, AFAIK you need to write some Assembly to do it. Running an assembler and linking it into a Rust program is pretty straight-forward. It would be nicer if one could use inline assembly (and let the compiler handle it for you), but that hasn't been stabilized yet. The topic of whether to build a Rust standard library without libc is definitely one that has gotten some attention, and some folks have made some progress on that front, but AFAIK there is no serious ongoing project or effort that attempts this. Some folks definitely desire it though, at least for Linux. (In other platforms, like macOS and Windows, raw syscalls aren't a stable interface, so you kind of need to use the system libraries.)