#

#include	"util.h"
#include	"pkts.h"
#include	"buf.h"
#include	<ioctl.h>

/* tcp_snd  send tcp pkt -
Send sequence no's. seqno to seqno + nseq.
Compute rcv window to advertise.  It is current
unused window until unused window is < 50% of max.
window; then max. window is advertised.
Update t_snxt if send new seqno's.
Clr t_acktime to indicate that ACK is not due.
*/
tcp_snd(ptcb, seqno, nseq)
register struct tcb	*ptcb;
long			seqno;
register int		nseq;
{
	register struct tcp_hdr	*tcp;
	short			dlen, maxsdata, uwnd;

	dlen = 0;
	tcp = &ptcb->t_tcp;
	tcp->tc_off = (TCPHSIZ << 2);

	if ((ptcb->t_state & (SYN_RCVD|FIN_RCVD)) == SYN_RCVD) {
		uwnd = ptcb->t_rlast - ptcb->t_rnxt;
		if (uwnd < (RWINDOW >> 1)) {
			ptcb->t_rwnd = RWINDOW;
			ptcb->t_rlast = ptcb->t_rnxt + RWINDOW;
			}
		else
			ptcb->t_rwnd = uwnd;
		}

	do {
		tcp->tc_flags &= (~(SYN|FIN|URG));
		tcp->tc_flags |= PSH;

		if (nseq)  {
			maxsdata = nseq <= ptcb->t_maxsdata ?
				nseq:ptcb->t_maxsdata;
			dlen = sb_pkt(ptcb, seqno, maxsdata);
			}

		tcp->tc_seqno = seqno;
		tcp->tc_ackno = ptcb->t_rnxt;
		tcp->tc_window = ptcb->t_rwnd;
		wr_tcp(ptcb, dlen);

		seqno += dlen;
		nseq -= dlen;
		if (tcp->tc_flags & SYN) {
			seqno++;
			nseq--;
			ptcb->t_state |= SYN_SENT;
			}
		if (tcp->tc_flags & FIN) {
			seqno++;
			nseq--;
			ptcb->t_state |= FIN_SENT;
			}
		} while (nseq > 0);

	if ((seqno - ptcb->t_snxt) > 0)
		ptcb->t_snxt = seqno;
	ptcb->t_acktime = 0;

	return(TRUE);
}

snd_reset(ptcb, ppkt)
struct tcb	*ptcb;
struct rcvpkt	*ppkt;
{
	register struct tcp_hdr		*tcp, *tcp2;
	register struct inet_hdr	*inp;
	short				iphlen, slen;
	char				flags;
	short				dskt;

	tcp2 = &ptcb->t_tcp;
	flags = tcp2->tc_flags;
	dskt = tcp2->tc_dskt;

	inp = &ppkt->rp_inet;
	iphlen = ((inp->ip_ihlver & 017) << 2);
	tcp = (char *) inp + iphlen;

	tcp2->tc_dskt = tcp->tc_sskt;
	tcp2->tc_off = (TCPHSIZ << 2);
	if (tcp->tc_flags & ACK) {
		tcp2->tc_flags = RST;
		tcp2->tc_seqno = tcp->tc_ackno;
		}
	else {
		tcp2->tc_flags = RST|ACK;
		tcp2->tc_seqno = 0;
		slen = inp->ip_len -
			(iphlen + ((tcp->tc_off & 0360) >> 2) );
		if (tcp->tc_flags & SYN) slen++;
		if (tcp->tc_flags & FIN) slen++;
		tcp2->tc_ackno = tcp->tc_seqno + slen;
		}
	wr_tcp(ptcb, 0);

	tcp2->tc_flags = flags;
	tcp2->tc_dskt = dskt;
	return;
}

wr_tcp(ptcb, dlen)
register struct tcb	*ptcb;
short			dlen;
{
	register struct tcp_hdr		*tcp;
	register struct inet_hdr	*inp;
	short				tcplen, iplen, plen;


	tcp = &ptcb->t_tcp;
	tcplen = dlen + ((tcp->tc_off & 0360) >> 2);

	tcp->tc_cksum = 0;

	if (prflag & PF_SND) {
		dmp_state();
		dmp_pkt("Packet sent\n", &ptcb->t_net, (tcplen + IPHSIZ));
		}

	tcp_swab(tcp);

	ptcb->t_phdr.pt_len = swab(tcplen);
	tcp->tc_cksum = ~cksum_tcp(&ptcb->t_phdr, tcp, tcplen);

	inp = &ptcb->t_inet;
	iplen = tcplen + IPHSIZ;
	inp->ip_len = swab(iplen);
	inp->ip_id = 0;

	plen = iplen + NETHSIZ;
	if (!wr_pkt(&ptcb->t_net, plen)) return(FALSE);

	return(TRUE);
}