Add support for OpenWRT

[safwanrahman]

Thanks a lot for the nice and useful package. As OpenWRT is also a linux distribution, is it possible to build a binary for OpenWRT?

[imsnif]

Sure, glad you like it :)

Does the generic binary in the releases work on OpenWRT?

[safwanrahman]

@imsnif The generic binary raises following error when I try to run it.

root@OpenWrt:/# ./bandwhich 
./bandwhich: line 1: syntax error: unexpected ")"

[imsnif]

Wow, that's really odd!

I don't know a lot about OpenWRT, but are you able to run other musl binaries normally? Could you walk me through the process you did from downloading the binary until running? Maybe there's a clue there?

[safwanrahman]

@imsnif I actually never run musl binary directly in OpenWRT. I will check more about running musl binary in OpenWRT.
I have downloaded the binary to my machine, copied it to OpenWRT then run chmod +X bandwhich and try to execute the binary with ./bandwhich.

Can you let me know where the building code reside?
Maybe this will be helpful: https://openwrt.org/docs/guide-developer/crosscompile

[Alcaro]

Sounds to me like your OpenWRT is installed on a non-x86 architecture and can't run x86_64 binaries. If execve() returns ENOEXEC (An executable is not in a recognized format, is for the wrong architecture, or has some other format error that means it cannot be executed.), the shell falls back to /bin/sh, which prints a ridiculous error.

To fix, compile for the correct architecture, not x86_64. To find which architecture you're on, use uname -m, -p, or -i (all three print x86_64 for me, I don't know what the difference is).

[safwanrahman]

@Alcaro I am using Linksys WRT3200ACM which seems like using arm processor.

uname -m print like following

root@OpenWrt:/# uname -m
armv7l

[imsnif]

@safwanrahman - I think your best bet in this case, as @Alcaro mentions, would be to compile the source with cargo (directly on the openwrt machine), as described here: https://github.com/imsnif/bandwhich#other-linux-flavours

[safwanrahman]

@imsnif Thanks. Can you guide me how you are building currently? As I need to build it in my host machine for ARM then transfer it to the router.

[Alcaro]

Compiling anything needs a lot of RAM, CPU and storage - resources which are typically not abundant on routers.

I think your best bet would be installing Cargo on a PC and telling it to cross compile. Googling 'rust openwrt' returns a few relevant-looking things, or you can try 'rust cross compile armv7l'.

Alternatively, you may be able to install an emulated armv7l environment on your PC, using (for example) QEMU. Emulating an ARM is slower than a native cross compiler, but may be easier to set up. Or maybe it's harder - I don't know how easy Rust is to cross compile.

[imsnif]

Thanks very much for your input @Alcaro! I think the idea of running bandwhich on OpenWRT is quite interesting. So @safwanrahman - if you get it to work, I would very much like to hear more. Maybe we could make it easier for others wanting to do this.

[safwanrahman]

@Alcaro Thanks for the suggestion. I have very less idea about rust toolchain as well as OpenWRT toolchain. I will try to find out how to fix it. Thanks for your suggestion.

@imsnif Can you let me know how do you build using cargo?

[imsnif]

I do a cargo build --release --target x86_64-unknown-linux-musl --locked on the source in order to build the musl binary, and a plain cargo build in order to build for the current machine.

Doing some searching, this seems like a good place to start: https://github.com/japaric/rust-cross

Please feel free to reach out if you're having trouble.

[TheLostLambda]

@imsnif The generic binary raises following error when I try to run it.

root@OpenWrt:/# ./bandwhich 
./bandwhich: line 1: syntax error: unexpected ")"

Hi! Sorry to jump in out of nowhere, but could you run file bandwhich or cat bandwhich on that executable? I suspect that if you downloaded things with curl, it might have ignored a redirect or something. That's certainly a shot in the dark, but should be easier to check and might save you from cross-compiling.

EDIT: Whoops, I totally missed the different CPU architecture, you'll likely still need to cross compile. Sorry about that!

[safwanrahman]

@TheLostLambda Thanks for the concern! I have run cat bandwhich which seems like a binary.

[safwanrahman]

@Alcaro @imsnif Do you have any idea which linker should I use?

[safwanrahman]

Seems like not possible at this moment because of rust bug rust-lang/rust#37507

[safwanrahman]

So after working a lot the night and day, Finally I have got a suggestion of my fellow friend @mominul to use rust-embedded/cross to cross compile for OpenWRT machine and it worked! 🥳 🚀

At first I compiled with mips-unknown-linux-musl target, but it did not work. But later I have read about the armv7 processor and compiled with armv7-unknown-linux-musleabihf target and It works like charm! 🎉🚀

[imsnif]

I'm really happy to hear that, @safwanrahman - great work!

Would you be willing to create a pull request to add these instructions to the README? I think it will be really helpful to others wanting to do the same. Either that or if you prefer, you can write down the commands you used here and I'll add it.

[safwanrahman]

@imsnif Sure, I am writing the process below. I am currently trying to figure out to cross compile for the targets so that it can be installed by the Opkg Package Manager.
I have done following:

• Check the processor of my router as suggested by @Alcaro by using uname -m
• Clone the repository
• Install cross using cargo install cross
• build the bandwhich package using cross build --target armv7-unknown-linux-musleabihf
• Copy the binary files from target/armv7-unknown-linux-musleabihf/debug/bandwhich to the router using scp by running scp bandwhich root@192.168.1.1:~/
• And finally enter the router using ssh and run the binary directly with ./bandwhich

@imsnif Can you arrange the instruction and write it down in the README? I can not figure out how to put it in there.

BTW, thanks a lot @Alcaro for pointing the architecture issue. I would have never found it if you did not mention in the earlier comment.

[imsnif]

Thank you very much @safwanrahman! I'll write it up in the README in the next few days.

[imsnif]

I added these instructions to the readme. Thanks again @safwanrahman for sharing these!

[smorimoto]

Oh, I just noticed this. I don't know why you were mentioning me, but I'm glad that this seems to have been closed.

[smorimoto]

By the way, since I don't use macOS anymore and use Windows (WSL2) and Void Linux, I will mainly update the Void Linux's package repository. Of course, it's not impossible for me to maintain Homebrew one, so please let me know if you need it.

[safwanrahman]

@imbsky Sorry for mentioning you! Github suggestion suggested your username when I tried to mention @imsnif and I did not notice it!

[smorimoto]

Oh, I see. No worries 🙂

[cyqsimon]

Since we're doing cross-compile stuff in #401, we might as well revisit this and add prebuilt binaries for armv7 targets.