[PATCH iproute2] ss: report ecnseen

[Eric Dumazet <eric.dumazet@gmail.com>]

Support ECNSEEN reporting in ss command.

ESTAB      0      0           10.170.73.123:4900
10.170.73.125:51001    uid:501 ino:385994 sk:f31e5f00
	 mem:(r0,w0,f0,t0) ts sack ecn ecnseen bic wscale:8,8 rto:210
rtt:18.75/15 ato:40 cwnd:10 send 69.9Mbps rcv_space:32768

"ecn" means TCP session negociated ECN capability at setup time

"ecnseen" at least one frame with ECT(0) or ECT(1) or ECN (IP layer) was
received from peer.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
 include/netinet/tcp.h |    1 +
 misc/ss.c             |    2 ++
 2 files changed, 3 insertions(+)

diff --git a/include/netinet/tcp.h b/include/netinet/tcp.h
index 282b29c..95a4fe6 100644
--- a/include/netinet/tcp.h
+++ b/include/netinet/tcp.h
@@ -172,6 +172,7 @@ enum
 # define TCPI_OPT_SACK		2
 # define TCPI_OPT_WSCALE	4
 # define TCPI_OPT_ECN		8
+# define TCPI_OPT_ECNSEEN	16
 
 /* Values for tcpi_state.  */
 enum tcp_ca_state
diff --git a/misc/ss.c b/misc/ss.c
index b00841b..778bf0a 100644
--- a/misc/ss.c
+++ b/misc/ss.c
@@ -1357,6 +1357,8 @@ static void tcp_show_info(const struct nlmsghdr *nlh, struct inet_diag_msg *r)
 				printf(" sack");
 			if (info->tcpi_options & TCPI_OPT_ECN)
 				printf(" ecn");
+			if (info->tcpi_options & TCPI_OPT_ECNSEEN)
+				printf(" ecnseen");
 		}
 
 		if (tb[INET_DIAG_CONG])