(Michael, I sent you this a while ago and didn't get any reply, so I
thought maybe it got lost somehow, that's why I'm resending it to the
linux-man list)
I just stumbled upon bind() returning -1 with errno set to ENODEV and
noticed that this value for errno is not documented in bind.2. I was
trying to bind to an IPv6 address.
I just checked the kernel code we are using, and then the one in
2.6.23 and noticed this in inet6_bind():
#
# if (addr_type & IPV6_ADDR_LINKLOCAL) {
# if (addr_len >= sizeof(struct sockaddr_in6) &&
# addr->sin6_scope_id) {
# /* Override any existing binding, if another one
# * is supplied by user.
# */
# sk->sk_bound_dev_if = addr->sin6_scope_id;
# }
#
# /* Binding to link-local address requires an interface */
# if (!sk->sk_bound_dev_if) {
# err = -EINVAL;
# goto out;
# }
# dev = dev_get_by_index(sk->sk_bound_dev_if);
# if (!dev) {
# err = -ENODEV;
# goto out;
# }
# }
Notice the err = -ENODEV because the value set in sin6_scope_id isn't
something we expect. We are indeed setting that in our code, and using
a link-local address. Now, 'man ipv6' says:
sin6_scope_id is an ID of depending of on the
scope of the address. It is new in Linux 2.4. Linux only
supports it for
link scope addresses, in that case sin6_scope_id contains
the interface
index (see netdevice(7))
So ENODEV is returned for IPv6 when using a link-local address and a
sin6_scope_id that doesn't include a valid interface index. The
manual page already has a section with errors specific to domain
sockets, I guess a new section with IPv6 specific errors would be
good.
Stefan.
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