[lwip-users] IPv6 Multicast TX socket options

[Sam Kearney]

Hi all,

 

I am using lwIP stable release 2.1.2, in an application using the sockets API. I see that the IPv4-specific multicast TX socket options are implemented (IP_MULTICAST_TTL, IP_MULTICAST_IF, IP_MULTICAST_LOOP) but not their IPv6 counterparts (IPV6_MULTICAST_HOPS, IPV6_MULTICAST_IF, IPV6_MULTICAST_LOOPS).

 

I do need these options in my application. If this is on the roadmap for a near future release (i.e. before end of this year), I can wait; otherwise, I’m wondering if there’s a way I haven’t noticed to short-circuit around the socket interface in this case.

 

It looks like if I was able to set the proper flags on the underlying UDP PCP (e.g. udp_set_multicast_ttl(), udp_set_multicast_netif_index()), as long as I was careful about synchronization with the TCP/IP thread, perhaps using LOCK_TCPIP_CORE() and UNLOCK_TCPIP_CORE() in my own code, it would work; but it looks like the only way to get the underlying netconn or PCB from a socket is in private code. This is probably as it should be… but I’m wondering if there’s a trick I can use to do this that I haven’t noticed.

 

Thanks in advance,

Sam