From: Willem de Bruijn <will...@google.com> On IP datagrams and raw sockets, when packets arrive fragmented, expose the largest received fragment size through a new cmsg.
Protocols implemented on top of these sockets may use this, for instance, to inform peers to lower MSS on platforms that silently allow send calls to exceed PMTU and cause fragmentation. Willem de Bruijn (3): ipv4: add IP_RECVFRAGSIZE cmsg ipv6: add IPV6_RECVFRAGSIZE cmsg ipv6: on reassembly, record frag_max_size include/linux/ipv6.h | 5 +++-- include/net/inet_sock.h | 1 + include/uapi/linux/in.h | 1 + include/uapi/linux/in6.h | 1 + net/ipv4/ip_sockglue.c | 26 ++++++++++++++++++++++++++ net/ipv6/datagram.c | 5 +++++ net/ipv6/ipv6_sockglue.c | 8 ++++++++ net/ipv6/reassembly.c | 7 ++++++- 8 files changed, 51 insertions(+), 3 deletions(-) -- 2.8.0.rc3.226.g39d4020
