tcp: set and get per-socket timestamp

avagin · davem330 · commit 93be6ce0e91b · 2013-02-13T13:22:15.000-05:00
A timestamp can be set, only if a socket is in the repair mode.

This patch adds a new socket option TCP_TIMESTAMP, which allows to
get and set current tcp times stamp.

Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: Alexey Kuznetsov &lt;kuznet@ms2.inr.ac.ru&gt;
Cc: James Morris &lt;jmorris@namei.org&gt;
Cc: Hideaki YOSHIFUJI &lt;yoshfuji@linux-ipv6.org&gt;
Cc: Patrick McHardy &lt;kaber@trash.net&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Pavel Emelyanov &lt;xemul@parallels.com&gt;
Signed-off-by: Andrey Vagin &lt;avagin@openvz.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
@@ -111,6 +111,7 @@ enum {
 #define TCP_QUEUE_SEQ		21
 #define TCP_REPAIR_OPTIONS	22
 #define TCP_FASTOPEN		23	/* Enable FastOpen on listeners */
+#define TCP_TIMESTAMP		24
 
 struct tcp_repair_opt {
 	__u32	opt_code;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
@@ -2714,6 +2714,12 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
 		else
 			err = -EINVAL;
 		break;
+	case TCP_TIMESTAMP:
+		if (!tp->repair)
+			err = -EPERM;
+		else
+			tp->tsoffset = val - tcp_time_stamp;
+		break;
 	default:
 		err = -ENOPROTOOPT;
 		break;
@@ -2962,6 +2968,9 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
 	case TCP_USER_TIMEOUT:
 		val = jiffies_to_msecs(icsk->icsk_user_timeout);
 		break;
+	case TCP_TIMESTAMP:
+		val = tcp_time_stamp + tp->tsoffset;
+		break;
 	default:
 		return -ENOPROTOOPT;
 	}
