[Bug]: socat UDP listen error, but netcat is fine

[brianwoo]

Problem description

I have this problem where socat cannot listen on any UDP port for some reason. Netcat can listen fine on the same UDP port. The error was xioopen_ipdgram_listen(): unknown address family 0. I have tried this on 2 different Android phones and I am getting the same error.

What steps will reproduce the bug?

From Termux, enter the following:

socat -dd udp-listen:1234,fork,reuseaddr,bind=127.0.0.1 -

The same UDP listen from netcat and worked:

nc -u -vv -l 1234

What is the expected behavior?

socat should be able to listen on udp port 1234.

System information

termux-info:

Termux Variables:
TERMUX_API_VERSION=0.50.1
TERMUX_APK_RELEASE=F_DROID
TERMUX_APP_PACKAGE_MANAGER=apt
TERMUX_APP_PID=7034
TERMUX_IS_DEBUGGABLE_BUILD=0
TERMUX_MAIN_PACKAGE_FORMAT=debian
TERMUX_VERSION=0.118.0
Packages CPU architecture:
aarch64
Subscribed repositories:
# sources.list
deb https://plug-mirror.rcac.purdue.edu/termux/termux-main stable main
# x11-repo (sources.list.d/x11.list)
deb https://plug-mirror.rcac.purdue.edu/termux/termux-x11 x11 main
# root-repo (sources.list.d/root.list)
deb https://plug-mirror.rcac.purdue.edu/termux/termux-root root stable
Updatable packages:
All packages up to date
termux-tools version:
1.39.5
Android version:
14
Kernel build information:
Linux localhost 5.10.177-android13-4-00003-ga7208022a7ea-ab10815828 #1 SMP PREEMPT Fri Sep 15 16:40:54 UTC 2023 aarch64 Android
Device manufacturer:
Google
Device model:
Pixel 6
LD Variables:
LD_LIBRARY_PATH=
LD_PRELOAD=/data/data/com.termux/files/usr/lib/libtermux-exec.so
Installed termux plugins:
com.termux.api versionCode:51

[licy183]

This is a bug of socat version 1.8.0.0. It is also reproducible on Alpine Linux 3.19 (with socat version 1.8.0.0), or even a newly built one.

[brianwoo]

Thanks very much for testing it. Really appreciate it.

[licy183]

I've submitted a temporary fix for it and have reported this issue upstream. I will not close this issue until upstream resolves it. Thanks for your report!

[ezekielnewren]

This is a bug of socat version 1.8.0.0. It is also reproducible on Alpine Linux 3.19 (with socat version 1.8.0.0), or even a newly built one.

I was trying to run 'socat UDP-LISTEN:5000,fork -' on Alpine Linux 3.19 and I got this error.

[licy183]

You need to report it to Alpine Linux or build socat from source with this patch.