Function bbr_log_output

freebsd/netinet/tcp_stacks/bbr.c:5911–6133

}

static void
bbr_log_output(struct tcp_bbr *bbr, struct tcpcb *tp, struct tcpopt *to, int32_t len,
    uint32_t seq_out, uint8_t th_flags, int32_t err, uint32_t cts,
    struct mbuf *mb, int32_t * abandon, struct bbr_sendmap *hintrsm, uint32_t delay_calc,
    struct sockbuf *sb)
{

	struct bbr_sendmap *rsm, *nrsm;
	register uint32_t snd_max, snd_una;
	uint32_t pacing_time;
	/*
	 * Add to the RACK log of packets in flight or retransmitted. If
	 * there is a TS option we will use the TS echoed, if not we will
	 * grab a TS.
	 *
	 * Retransmissions will increment the count and move the ts to its
	 * proper place. Note that if options do not include TS's then we
	 * won't be able to effectively use the ACK for an RTT on a retran.
	 *
	 * Notes about r_start and r_end. Lets consider a send starting at
	 * sequence 1 for 10 bytes. In such an example the r_start would be
	 * 1 (starting sequence) but the r_end would be r_start+len i.e. 11.
	 * This means that r_end is actually the first sequence for the next
	 * slot (11).
	 *
	 */
	INP_WLOCK_ASSERT(tp->t_inpcb);
	if (err) {
		/*
		 * We don't log errors -- we could but snd_max does not
		 * advance in this case either.
		 */
		return;
	}
	if (th_flags & TH_RST) {
		/*
		 * We don't log resets and we return immediately from
		 * sending
		 */
		*abandon = 1;
		return;
	}
	snd_una = tp->snd_una;
	if (th_flags & (TH_SYN | TH_FIN) && (hintrsm == NULL)) {
		/*
		 * The call to bbr_log_output is made before bumping
		 * snd_max. This means we can record one extra byte on a SYN
		 * or FIN if seq_out is adding more on and a FIN is present
		 * (and we are not resending).
		 */
		if ((th_flags & TH_SYN) && (tp->iss == seq_out))
			len++;
		if (th_flags & TH_FIN)
			len++;
	}
	if (SEQ_LEQ((seq_out + len), snd_una)) {
		/* Are sending an old segment to induce an ack (keep-alive)? */
		return;