tun: create tun_name_is_fixed helper
This helper encloses the (simple) logic used by OpenVPN to determine if
the name passed to --dev has to be considered a fixed interface name or
just a pattern.
Having a helper is useful because when this logic is required elsewhere,
we can just re-use this logic without duplicating the code (which may
mean introducing bugs if a future logic change should not update all
spots).
The logic is actually fairly simple: check if the name contains a number
(i.e. tun0). If so, consider the name a fixed device name.
While at it make has_digit() accept a signed argument because strings
are normally signed (also isdigit() accepts a signed argument).
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <
20220712221655.19333-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg24676.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>