/**
* Insert segment into the list (segments covered with new one will be deleted)
*
* Called from tcp_receive()
*/
static void
tcp_oos_insert_segment(struct tcp_seg *cseg, struct tcp_seg *next)
{
struct tcp_seg *old_seg;
if (TCPH_FLAGS(cseg->tcphdr) & TCP_FIN) {
/* received segment overlaps all following segments */
tcp_segs_free(next);
next = NULL;
} else {
/* delete some following segments
oos queue may have segments with FIN flag */
while (next &&
TCP_SEQ_GEQ((seqno + cseg->len),
(next->tcphdr->seqno + next->len))) {
/* cseg with FIN already processed */
if (TCPH_FLAGS(next->tcphdr) & TCP_FIN) {
TCPH_FLAGS_SET(cseg->tcphdr, TCPH_FLAGS(cseg->tcphdr) | TCP_FIN);
}
old_seg = next;
next = next->next;
tcp_seg_free(old_seg);
}
if (next &&
TCP_SEQ_GT(seqno + cseg->len, next->tcphdr->seqno)) {
/* We need to trim the incoming segment. */
cseg->len = (u16_t)(next->tcphdr->seqno - seqno);
pbuf_realloc(cseg->p, cseg->len);
}
}
cseg->next = next;
}
/**
* Update the state that tracks the available window space to advertise.
*
* Returns how much extra window would be advertised if we sent an
* update now.
*/
u32_t tcp_update_rcv_ann_wnd(struct tcp_pcb *pcb)
{
u32_t new_right_edge = pcb->rcv_nxt + pcb->rcv_wnd;
if (TCP_SEQ_GEQ(new_right_edge, pcb->rcv_ann_right_edge + LWIP_MIN((TCP_WND / 2), pcb->mss))) {
/* we can advertise more window */
pcb->rcv_ann_wnd = pcb->rcv_wnd;
return new_right_edge - pcb->rcv_ann_right_edge;
} else {
if (TCP_SEQ_GT(pcb->rcv_nxt, pcb->rcv_ann_right_edge)) {
/* Can happen due to other end sending out of advertised window,
* but within actual available (but not yet advertised) window */
pcb->rcv_ann_wnd = 0;
} else {
/* keep the right edge of window constant */
pcb->rcv_ann_wnd = pcb->rcv_ann_right_edge - pcb->rcv_nxt;
}
return 0;
}
}