[MPTCP] [MPTCP][PATCH v10 mptcp-next 3/9] mptcp: add a new helper subflow_req_create_thmac

[MPTCP] [MPTCP][PATCH v10 mptcp-next 3/9] mptcp: add a new helper subflow_req_create_thmac

[Geliang Tang]

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This patch added a new helper named subflow_req_create_thmac, which split
from subflow_token_join_request. It initialized subflow_req's local_nonce
and thmac fields, those are the more expensive to populate.

Signed-off-by: Geliang Tang <geliangtang(a)gmail.com>
---
 net/mptcp/subflow.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 700a87ee39f1..fee38bb9d80a 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -61,10 +61,23 @@ static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
 }
 
 /* validate received token and create truncated hmac and nonce for SYN-ACK */
+static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
+{
+	struct mptcp_sock *msk = subflow_req->msk;
+	u8 hmac[SHA256_DIGEST_SIZE];
+
+	get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
+
+	subflow_generate_hmac(msk->local_key, msk->remote_key,
+			      subflow_req->local_nonce,
+			      subflow_req->remote_nonce, hmac);
+
+	subflow_req->thmac = get_unaligned_be64(hmac);
+}
+
 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
 {
 	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
-	u8 hmac[SHA256_DIGEST_SIZE];
 	struct mptcp_sock *msk;
 	int local_id;
 
@@ -81,13 +94,6 @@ static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
 	}
 	subflow_req->local_id = local_id;
 
-	get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
-
-	subflow_generate_hmac(msk->local_key, msk->remote_key,
-			      subflow_req->local_nonce,
-			      subflow_req->remote_nonce, hmac);
-
-	subflow_req->thmac = get_unaligned_be64(hmac);
 	return msk;
 }
 
@@ -183,6 +189,8 @@ static int subflow_init_req(struct request_sock *req,
 		if (!subflow_req->msk)
 			return -EPERM;
 
+		subflow_req_create_thmac(subflow_req);
+
 		if (unlikely(req->syncookie)) {
 			if (mptcp_can_accept_new_subflow(subflow_req->msk))
 				subflow_init_req_cookie_join_save(subflow_req, skb);
-- 
2.29.2