[pkg-dhcp-devel] Bug#859094: isc-dhcp-client: dhclient fails if the interface name is too long

[dbx12]

Package: isc-dhcp-client
Version: 4.3.1-6+deb8u2
Severity: important
Tags: patch

Dear Maintainer,

I have an issue with dhclient, if I try to connect to an wireless network via USB dongle. According to syslog everything goes well until the address association via DHCP. Disabling DHCP and setting a static IP in the client also fixes the issue, so I think we can narrow it down to dhclient.
The error displayed in syslog is as follows:

Bind socket to interface: No such device

Thanks to unix.stackexchange.com I was able to create a workaround for it. There seems to be a problem with the buffer size of the interface name. The buffer is too small to hold a complete "predictable network interface name" (not sure why wlx112233445566 is more predictable than wlan0 but that's another story), so my proposed fix is to increase the size of said buffer.

The workaround is to rename the device with the long name to "wlan0" or something similar via an udev rule. 
Hopefully I added all necessary information to resolve the problem.

Cheers from Germany
DBX12


-- System Information:
Debian Release: 8.7
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: armhf (armv7l)

Kernel: Linux 3.10.105+ (SMP w/8 CPU cores; PREEMPT)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: sysvinit (via /sbin/init)

Versions of packages isc-dhcp-client depends on:
ii  debianutils       4.4+b1
ii  iproute2          3.16.0-2
ii  isc-dhcp-common   4.3.1-6+deb8u2
ii  libc6             2.19-18+deb8u7
ii  libdns-export100  1:9.9.5.dfsg-9+deb8u10
ii  libirs-export91   1:9.9.5.dfsg-9+deb8u10
ii  libisc-export95   1:9.9.5.dfsg-9+deb8u10

isc-dhcp-client recommends no packages.

Versions of packages isc-dhcp-client suggests:
pn  avahi-autoipd  <none>
pn  resolvconf     <none>

-- no debconf information