Cross-compilation on arm and mips devices

[cyadron]

Hello,

I have successfully cross-compiled microsocks on mips and also on arm devices.
On mips devices it works good so far.
But I have a strange issue when I tested on arm devices.
Some sites fail to load (like google.com, yahoo.com) with an error message (reported by proxifier) - Address type not supported.
But some sites load fine (except for elements from google.com domain) - like github.com
What could be the issue because this does not happen on mips devices?

[rofl0r]

does it work when you add -fsigned-char to your CFLAGS ?

[cyadron]

Unfortunately no.
Still no go.
I am getting other error also (with the original and the fsigned-char version).
Proxy server cannot establish a connection with the target - Network unreachable.
But some sites load fine.

[rofl0r]

well from a C language PoV the only difference between x86 and ARM is that ARM defaults to char == unsigned char.
so i'd suspect that your issues are related to the specific ARM box you use - maybe some firewall rules, or a bad connection ?

[cyadron]

I have tested another socks server on the same device and it loads the sites ok.
Any other idea?

[rofl0r]

you could try this: #6 - increasing the stacksize

maybe for some reason the ARM implementation of GLIBC or whatever LIBC you use (which one is it?) wastes more RAM, and since google has a ton of DNS elements in its response it's sufficient to overwrite things and cause weird hickups.

[cyadron]

Until now I was using release 0.1.0.
Now I am using the latest commit but I still have the problem.
I have tried to set size_t stacksz = 512 * 1024; but nothing changed.
The C library is uclibc.
And I do get the warning that this library sucks when I cross-compile it but no other warning/errors.
The error specified by proxifier is:

• Proxy server cannot establish a connection with the target - Address type not supported.

and I get no other output/error on the arm machine where microsocks is running.
Could the uclibc library create this problem?

[cyadron]

After more testing I find out that resolving hostnames through the socks server option causes problems.
If I use an external dns server the sites load fine.
I see that this is one difference between uclibc and glibc.
According to this paper:
https://mirrors.edge.kernel.org/pub/linux/libs/uclibc/Glibc_vs_uClibc_Differences.txt
uclibc does not support DNS resolution.
But since some sites load, I guess it is partially supported?

[rofl0r]

yes, uclibc could be the culprit. i'd strongly suggest to use musl instead to build tiny static-linked binaries (build your own toolchain from the scripts in https://github.com/richfelker/musl-cross-make)

[cyadron]

Hi,

I finally built microsocks using musl.
I have used the option for static-linked binaries and I was able to compile microsocks.
I ended up with a binary 3 times bigger (64 KB).
But the good news is that it works. Resolving hostnames finally works.
So this workaround is good but I guess there is no way to make it work with the default compiler?

[rofl0r]

hi, if you want a smaller binary you can try use the following flags in config.mak:

CFLAGS = -Os -flto
LDFLAGS = -s -flto

as for making it work with your uclibc toolchain: did you try latest git ? some bugs have been fixed since you opened your issue.

[hdbreaker]

Hi @cyadron could you explain to me the steps to cross-compile the project to mipsle32?