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tcp: use tcp_v4_send_synack on first SYN-ACK

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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 <ycheng@google.com>
Signed-off-by: Daniel Lee <longinus00@gmail.com>
Signed-off-by: Jerry Chu <hkchu@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng
2014-05-11 20:22:11 -07:00
committed by David S. Miller
parent 89278c9dc9
commit 843f4a55e3
5 changed files with 85 additions and 105 deletions
Download Patch File Download Diff File Expand all files Collapse all files

57
net/ipv4/tcp_ipv4.c
View File

@@ -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;