[RFC PATCH 6/7] tcp6: Support for TOU

[Tom Herbert <tom@herbertland.com>]

Need to adjust MSS to account for encapsulation overhead. This is done
by add encpasulation header length into icsk_ext_hdr_len.

Signed-off-by: Tom Herbert <tom@herbertland.com>
---
 net/ipv6/tcp_ipv6.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 79e33e0..6a3c2e7 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -62,6 +62,7 @@
 #include <net/inet_common.h>
 #include <net/secure_seq.h>
 #include <net/busy_poll.h>
+#include <net/tou.h>
 
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -210,7 +211,7 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 		err = tcp_v4_connect(sk, (struct sockaddr *)&sin, sizeof(sin));
 
 		if (err) {
-			icsk->icsk_ext_hdr_len = exthdrlen;
+			icsk->icsk_ext_hdr_len = tou_hdr_len(sk) + exthdrlen;
 			icsk->icsk_af_ops = &ipv6_specific;
 			sk->sk_backlog_rcv = tcp_v6_do_rcv;
 #ifdef CONFIG_TCP_MD5SIG
@@ -262,9 +263,9 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 	    ipv6_addr_equal(&fl6.daddr, &sk->sk_v6_daddr))
 		tcp_fetch_timewait_stamp(sk, dst);
 
-	icsk->icsk_ext_hdr_len = 0;
+	icsk->icsk_ext_hdr_len = tou_hdr_len(sk);
 	if (opt)
-		icsk->icsk_ext_hdr_len = opt->opt_flen +
+		icsk->icsk_ext_hdr_len += opt->opt_flen +
 					 opt->opt_nflen;
 
 	tp->rx_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
@@ -1114,9 +1115,9 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 		opt = ipv6_dup_options(newsk, opt);
 		RCU_INIT_POINTER(newnp->opt, opt);
 	}
-	inet_csk(newsk)->icsk_ext_hdr_len = 0;
+	inet_csk(newsk)->icsk_ext_hdr_len = tou_hdr_len(sk);
 	if (opt)
-		inet_csk(newsk)->icsk_ext_hdr_len = opt->opt_nflen +
+		inet_csk(newsk)->icsk_ext_hdr_len += opt->opt_nflen +
 						    opt->opt_flen;
 
 	tcp_ca_openreq_child(newsk, dst);
-- 
2.8.0.rc2