On Thu, 14 Apr 2022 16:04:22 GMT, Michael McMahon <micha...@openjdk.org> wrote:
> Hi,
>
> Could I get the following PR review please? It adds a new JDK specific
> extended socket option
> called IP_DONTFRAGMENT, which disables IP packet fragmentation in both IPv4
> and IPv6
> UDP sockets (NIO DatagramChannels). For IPv4 in particular, it sets the DF
> (Dont Fragment) bit
> in the IP header. There is no equivalent in the IPv6 packet header as
> fragmentation is implemented
> exclusively by the sending and receiving nodes.
>
> Thanks,
> Michael
src/jdk.net/windows/native/libextnet/WindowsSocketOptions.c line 73:
> 71: if (family == AF_INET) {
> 72: opt = optval;
> 73: rv = setsockopt(fd, IPPROTO_IP, IP_DONTFRAGMENT, (char *)&opt,
> sizeof(int));
Why do we only use `IPV6_MTU_DISCOVER` but not `IP_MTU_DISCOVER`? As far as I
can tell, `IP_DONTFRAGMENT` alone doesn't guarantee that the DF bit will be set.
-------------
PR: https://git.openjdk.java.net/jdk/pull/8245
