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/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _TCP_ECN_H
#define _TCP_ECN_H
#include <linux/tcp.h>
#include <linux/skbuff.h>
#include <net/inet_connection_sock.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <net/inet_ecn.h>
static inline void tcp_ecn_queue_cwr(struct tcp_sock *tp)
{
if (tcp_ecn_mode_rfc3168(tp))
tp->ecn_flags |= TCP_ECN_QUEUE_CWR;
}
static inline void tcp_ecn_accept_cwr(struct sock *sk,
const struct sk_buff *skb)
{
if (tcp_hdr(skb)->cwr) {
tcp_sk(sk)->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
/* If the sender is telling us it has entered CWR, then its
* cwnd may be very low (even just 1 packet), so we should ACK
* immediately.
*/
if (TCP_SKB_CB(skb)->seq != TCP_SKB_CB(skb)->end_seq)
inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
}
}
static inline void tcp_ecn_withdraw_cwr(struct tcp_sock *tp)
{
tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR;
}
static inline void tcp_ecn_rcv_synack(struct tcp_sock *tp,
const struct tcphdr *th)
{
if (tcp_ecn_mode_rfc3168(tp) && (!th->ece || th->cwr))
tcp_ecn_mode_set(tp, TCP_ECN_DISABLED);
}
static inline void tcp_ecn_rcv_syn(struct tcp_sock *tp,
const struct tcphdr *th)
{
if (tcp_ecn_mode_rfc3168(tp) && (!th->ece || !th->cwr))
tcp_ecn_mode_set(tp, TCP_ECN_DISABLED);
}
static inline bool tcp_ecn_rcv_ecn_echo(const struct tcp_sock *tp,
const struct tcphdr *th)
{
if (th->ece && !th->syn && tcp_ecn_mode_rfc3168(tp))
return true;
return false;
}
/* Packet ECN state for a SYN-ACK */
static inline void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb)
{
const struct tcp_sock *tp = tcp_sk(sk);
TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR;
if (tcp_ecn_disabled(tp))
TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE;
else if (tcp_ca_needs_ecn(sk) ||
tcp_bpf_ca_needs_ecn(sk))
INET_ECN_xmit(sk);
}
/* Packet ECN state for a SYN. */
static inline void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk);
bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 ||
tcp_ca_needs_ecn(sk) || bpf_needs_ecn;
if (!use_ecn) {
const struct dst_entry *dst = __sk_dst_get(sk);
if (dst && dst_feature(dst, RTAX_FEATURE_ECN))
use_ecn = true;
}
tp->ecn_flags = 0;
if (use_ecn) {
if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn)
INET_ECN_xmit(sk);
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR;
tcp_ecn_mode_set(tp, TCP_ECN_MODE_RFC3168);
}
}
static inline void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb)
{
if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback))
/* tp->ecn_flags are cleared at a later point in time when
* SYN ACK is ultimatively being received.
*/
TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR);
}
static inline void
tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th)
{
if (inet_rsk(req)->ecn_ok)
th->ece = 1;
}
#endif /* _LINUX_TCP_ECN_H */
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