From: Eric Dumazet <eduma...@google.com> In commit f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as ancillary data") Francesco added IP_TOS values specified as integer.
However, kernel sends to userspace (at recvmsg() time) an IP_TOS value in a single byte, when IP_RECVTOS is set on the socket. It can be very useful to reflect all ancillary options as given by the kernel in a subsequent sendmsg(), instead of aborting the sendmsg() with EINVAL after Francesco patch. So this patch extends IP_TOS ancillary to accept an u8, so that an UDP server can simply reuse same ancillary block without having to mangle it. Jesper can then augment https://github.com/netoptimizer/network-testing/blob/master/src/udp_example02.c to add TOS reflection ;) Fixes: f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as ancillary data") Signed-off-by: Eric Dumazet <eduma...@google.com> Cc: Francesco Fusco <ffu...@redhat.com> Cc: Jesper Dangaard Brouer <bro...@redhat.com> --- net/ipv4/ip_sockglue.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 71a52f4d4cffba2db9353f43dc817689bf4fab10..af4919792b6a812041dcb18ff30aa8b27482c7a2 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -284,9 +284,12 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc, ipc->ttl = val; break; case IP_TOS: - if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) + if (cmsg->cmsg_len == CMSG_LEN(sizeof(int))) + val = *(int *)CMSG_DATA(cmsg); + else if (cmsg->cmsg_len == CMSG_LEN(sizeof(u8))) + val = *(u8 *)CMSG_DATA(cmsg); + else return -EINVAL; - val = *(int *)CMSG_DATA(cmsg); if (val < 0 || val > 255) return -EINVAL; ipc->tos = val;