udhcpc6 kernel listen mode is broken

[Denys Vlasenko]

Fixed, thank you. Can you try current git?

On Sat, Jun 4, 2022 at 2:58 AM Danomi Manchego
<danomimanchego123 at gmail.com> wrote:
>
> Sorry all, I did not realize that there was a function called
> d6_listen_socket() in d6_socket.c - so no new function is needed to
> fix DHCPv6 Renew reply processing.  The correct message ID is needed
> and use of d6_listen_socket() rather than udhcp_listen_socket().
>
> Regards,
> Danomi -
>
> On Tue, May 10, 2022 at 9:34 PM Danomi Manchego
> <danomimanchego123 at gmail.com> wrote:
> >
> > Hello,
> >
> > On April 1, I sent "udhcpc6 renew message copy/paste error" email
> > about udhcpc6 sends the wrong message ID for Renew message due to
> > copy/paste error from IPv4 dhcpc.c.  (Was DHCPREQUEST, should be
> > D6_MSG_RENEW.)  After fixing that, I found that the Renew is sent
> > correctly, and the DHCPv6 server replies, but udhcpc6 fails to get the
> > reply.  Because there is no reply, the lease does not get extended by
> > Renew.  I found that the issue is that the udhcp_listen_socket() in
> > socket.c (used for kernel listen mode in d6_dhcpc.c) is somewhat
> > hard-coded for IPv4.  I was able to get kernel listen mode to work by
> > adding a new function like this to socket.c and using it in d6_dhcp.c.
> > My udhcp6_listen_socket() differs from udhcp_listen_socket() as
> > follows:
> >
> > * Use PF_INET6 instead of PF_INET.
> >
> > * Set IPPROTO_IPV6 / IPV6_V6ONLY socket option rather than broadcast option.
> >
> > * Use `struct sockaddr_in6` instead of `struct sockaddr_in`.
> >
> > * Use AF_INET6 instead of AF_INET.
> >
> > (Maybe SOCK_CLOEXEC should also be set in *both* functions when
> > calling xsocket since udhcpc/udhcpc6 invoke external udhcpc.script,
> > but I did not try it.)
> >
> > My function is pasted below.
> >
> > int FAST_FUNC udhcp6_listen_socket(/*uint32_t ip,*/ int port, const char *inf)
> > {
> >     int fd;
> >     struct sockaddr_in6 addr;
> >     char *colon;
> >
> >     log2("opening listen socket on *:%d %s", port, inf);
> >     fd = xsocket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
> >
> >     setsockopt_reuseaddr(fd);
> >
> >     if (setsockopt_1(fd, IPPROTO_IPV6, IPV6_V6ONLY) < 0)
> >         bb_simple_perror_msg_and_die("IPPROTO_IPV6");
> >
> >     /* SO_BINDTODEVICE doesn't work on ethernet aliases (ethN:M) */
> >     colon = strrchr(inf, ':');
> >     if (colon)
> >         *colon = '\0';
> >
> >     if (setsockopt_bindtodevice(fd, inf))
> >         xfunc_die(); /* warning is already printed */
> >
> >     if (colon)
> >         *colon = ':';
> >
> >     memset(&addr, 0, sizeof(addr));
> >     addr.sin6_family = AF_INET6;
> >     addr.sin6_port = htons(port);
> >     /* addr.sin_addr.s_addr = ip; - all-zeros is INADDR_ANY */
> >     xbind(fd, (struct sockaddr *)&addr, sizeof(addr));
> >
> >     return fd;
> > }
> >
> > Regards,
> > Danomi -
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