[PATCH v2 2/7] net-tcp: Fast Open client - cookie cache

[Yuchung Cheng <ycheng@google.com>]

Add Fast Open metrics in tcp metrics cache: the basic ones are MSS and
the cookies. Later patch will cache more to handle unfriendly middleboxes.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
---
 include/net/tcp.h      |    4 ++++
 net/ipv4/tcp_metrics.c |   41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 5aed371..e601da1 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -405,6 +405,10 @@ extern void tcp_metrics_init(void);
 extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check);
 extern bool tcp_remember_stamp(struct sock *sk);
 extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
+extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
+				   struct tcp_fastopen_cookie *cookie);
+extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
+				   struct tcp_fastopen_cookie *cookie);
 extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
 extern void tcp_disable_fack(struct tcp_sock *tp);
 extern void tcp_close(struct sock *sk, long timeout);
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index 1a115b6..b498954 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -30,6 +30,11 @@ enum tcp_metric_index {
 	TCP_METRIC_MAX,
 };
 
+struct tcp_fastopen_metrics {
+	u16	mss;
+	struct	tcp_fastopen_cookie	cookie;
+};
+
 struct tcp_metrics_block {
 	struct tcp_metrics_block __rcu	*tcpm_next;
 	struct inetpeer_addr		tcpm_addr;
@@ -38,6 +43,7 @@ struct tcp_metrics_block {
 	u32				tcpm_ts_stamp;
 	u32				tcpm_lock;
 	u32				tcpm_vals[TCP_METRIC_MAX];
+	struct tcp_fastopen_metrics	tcpm_fastopen;
 };
 
 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
@@ -118,6 +124,8 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst)
 	tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
 	tm->tcpm_ts = 0;
 	tm->tcpm_ts_stamp = 0;
+	tm->tcpm_fastopen.mss = 0;
+	tm->tcpm_fastopen.cookie.len = 0;
 }
 
 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
@@ -633,6 +641,39 @@ bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 	return ret;
 }
 
+void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
+			    struct tcp_fastopen_cookie *cookie)
+{
+	struct tcp_metrics_block *tm;
+
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
+	if (tm) {
+		struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
+		if (tfom->mss)
+			*mss = tfom->mss;
+		*cookie = tfom->cookie;
+	}
+	rcu_read_unlock();
+}
+
+
+void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
+			    struct tcp_fastopen_cookie *cookie)
+{
+	struct tcp_metrics_block *tm;
+
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, __sk_dst_get(sk), true);
+	if (tm) {
+		struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
+		tfom->mss = mss;
+		if (cookie->len > 0)
+			tfom->cookie = *cookie;
+	}
+	rcu_read_unlock();
+}
+
 static unsigned long tcpmhash_entries;
 static int __init set_tcpmhash_entries(char *str)
 {
-- 
1.7.7.3