From 843f4a55e336e6d0c7bb92e7f9621535bc8d5fcd Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Sun, 11 May 2014 20:22:11 -0700 Subject: tcp: use tcp_v4_send_synack on first SYN-ACK To avoid large code duplication in IPv6, we need to first simplify the complicate SYN-ACK sending code in tcp_v4_conn_request(). To use tcp_v4(6)_send_synack() to send all SYN-ACKs, we need to initialize the mini socket's receive window before trying to create the child socket and/or building the SYN-ACK packet. So we move that initialization from tcp_make_synack() to tcp_v4_conn_request() as a new function tcp_openreq_init_req_rwin(). After this refactoring the SYN-ACK sending code is simpler and easier to implement Fast Open for IPv6. Signed-off-by: Yuchung Cheng Signed-off-by: Daniel Lee Signed-off-by: Jerry Chu Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 57 +++++++++++++++-------------------------------------- 1 file changed, 16 insertions(+), 41 deletions(-) (limited to 'net/ipv4/tcp_ipv4.c') diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 5ea0949dadfd..1665f0f84233 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -822,7 +822,8 @@ static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, */ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst, struct request_sock *req, - u16 queue_mapping) + u16 queue_mapping, + struct tcp_fastopen_cookie *foc) { const struct inet_request_sock *ireq = inet_rsk(req); struct flowi4 fl4; @@ -833,7 +834,7 @@ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst, if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL) return -1; - skb = tcp_make_synack(sk, dst, req, NULL); + skb = tcp_make_synack(sk, dst, req, foc); if (skb) { __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr); @@ -852,7 +853,7 @@ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst, static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req) { - int res = tcp_v4_send_synack(sk, NULL, req, 0); + int res = tcp_v4_send_synack(sk, NULL, req, 0, NULL); if (!res) { TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS); @@ -1270,11 +1271,10 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) __be32 saddr = ip_hdr(skb)->saddr; __be32 daddr = ip_hdr(skb)->daddr; __u32 isn = TCP_SKB_CB(skb)->when; - bool want_cookie = false; + bool want_cookie = false, fastopen; struct flowi4 fl4; struct tcp_fastopen_cookie foc = { .len = -1 }; - struct sk_buff *skb_synack; - int do_fastopen; + int err; /* Never answer to SYNs send to broadcast or multicast */ if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) @@ -1373,49 +1373,24 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) isn = tcp_v4_init_sequence(skb); } - tcp_rsk(req)->snt_isn = isn; - - if (dst == NULL) { - dst = inet_csk_route_req(sk, &fl4, req); - if (dst == NULL) - goto drop_and_free; - } - do_fastopen = !want_cookie && - tcp_fastopen_check(sk, skb, req, &foc); - - /* We don't call tcp_v4_send_synack() directly because we need - * to make sure a child socket can be created successfully before - * sending back synack! - * - * XXX (TFO) - Ideally one would simply call tcp_v4_send_synack() - * (or better yet, call tcp_send_synack() in the child context - * directly, but will have to fix bunch of other code first) - * after syn_recv_sock() except one will need to first fix the - * latter to remove its dependency on the current implementation - * of tcp_v4_send_synack()->tcp_select_initial_window(). - */ - skb_synack = tcp_make_synack(sk, dst, req, &foc); - - if (skb_synack) { - __tcp_v4_send_check(skb_synack, ireq->ir_loc_addr, ireq->ir_rmt_addr); - skb_set_queue_mapping(skb_synack, skb_get_queue_mapping(skb)); - } else + if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL) goto drop_and_free; - if (likely(!do_fastopen)) { - int err; - err = ip_build_and_send_pkt(skb_synack, sk, ireq->ir_loc_addr, - ireq->ir_rmt_addr, ireq->opt); - err = net_xmit_eval(err); + tcp_rsk(req)->snt_isn = isn; + tcp_rsk(req)->snt_synack = tcp_time_stamp; + tcp_openreq_init_rwin(req, sk, dst); + fastopen = !want_cookie && + tcp_try_fastopen(sk, skb, req, &foc, dst); + err = tcp_v4_send_synack(sk, dst, req, + skb_get_queue_mapping(skb), &foc); + if (!fastopen) { if (err || want_cookie) goto drop_and_free; tcp_rsk(req)->snt_synack = tcp_time_stamp; tcp_rsk(req)->listener = NULL; - /* Add the request_sock to the SYN table */ inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT); - } else if (tcp_fastopen_create_child(sk, skb, skb_synack, req)) - goto drop_and_release; + } return 0; -- cgit v1.2.3-59-g8ed1b