ipv6: add the IPV6_FL_F_REFLECT flag to IPV6_FL_A_GET

With this option, the socket will reply with the flow label value read
on received packets.

The goal is to have a connection with the same flow label in both
direction of the communication.

Changelog of V4:
 * Do not erase the flow label on the listening socket. Use pktopts to
 store the received value

Signed-off-by: Florent Fourcot <florent.fourcot@enst-bretagne.fr>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 7e1ded0d8e45..1084304fd75a 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -191,6 +191,7 @@ struct ipv6_pinfo {
         /* sockopt flags */
         __u16                   recverr:1,
                                 sndflow:1,
+                                repflow:1,
                                 pmtudisc:3,
                                 ipv6only:1,
                                 srcprefs:3,     /* 001: prefer temporary address
diff --git a/include/uapi/linux/in6.h b/include/uapi/linux/in6.h
index f94f1d013bf2..02c0cd685a27 100644
--- a/include/uapi/linux/in6.h
+++ b/include/uapi/linux/in6.h
@@ -85,6 +85,7 @@ struct in6_flowlabel_req {
 
 #define IPV6_FL_F_CREATE        1
 #define IPV6_FL_F_EXCL          2
+#define IPV6_FL_F_REFLECT       4
 
 #define IPV6_FL_S_NONE          0
 #define IPV6_FL_S_EXCL          1