[PATCH 3/3] conf: More useful errors for kernels without SO_BINDTODEVICE

Before 5.7, the kernel didn't allow SO_BINDTODEVICE to be called unprivileged. That means for earlier kernels, we can't implement binding listening sockets to a specific interface (e.g. -t %eth0/80). Currently we'll generate an error on this at the point we actually attempt the SO_BINDTODEVICE setsockopt(), at which point the connection to the command line option might not be entirely clear. Use the fact we now probe for SO_BINDTODEVICE support to make a clearer error message at the time we parse the forwarding option. Signed-off-by: David Gibson --- conf.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/conf.c b/conf.c index 66b9e634..43bcaf31 100644 --- a/conf.c +++ b/conf.c @@ -156,6 +156,12 @@ static void conf_ports_range_except(const struct ctx *c, char optname, optname, optarg); } + if (ifname && c->no_bindtodevice) { + die( +"Device binding for '-%c %s' unsupported (requires kernel 5.7+)", + optname, optarg); + } + for (i = first; i <= last; i++) { if (bitmap_isset(exclude, i)) continue; -- 2.51.1