/*

 * Copyright (c) 1995 Danny Gasparovski.

 *

 * Please read the file COPYRIGHT for the

 * terms and conditions of the copyright.

 */

#include <slirp.h>

int     if_queued = 0;                  /* Number of packets queued so far */

struct  mbuf if_fastq;                  /* fast queue (for interactive data) */

struct  mbuf if_batchq;                 /* queue for non-interactive data */

struct	mbuf *next_m;			/* Pointer to next mbuf to output */

#define ifs_init(ifm) ((ifm)->ifs_next = (ifm)->ifs_prev = (ifm))

static void

ifs_insque(struct mbuf *ifm, struct mbuf *ifmhead)

{

	ifm->ifs_next = ifmhead->ifs_next;

	ifmhead->ifs_next = ifm;

	ifm->ifs_prev = ifmhead;

	ifm->ifs_next->ifs_prev = ifm;

}

static void

ifs_remque(struct mbuf *ifm)

{

	ifm->ifs_prev->ifs_next = ifm->ifs_next;

	ifm->ifs_next->ifs_prev = ifm->ifs_prev;

}

void

if_init()

{

	if_fastq.ifq_next = if_fastq.ifq_prev = &if_fastq;

	if_batchq.ifq_next = if_batchq.ifq_prev = &if_batchq;

        //	sl_compress_init(&comp_s);

	next_m = &if_batchq;

}

#if 0

/*

 * This shouldn't be needed since the modem is blocking and

 * we don't expect any signals, but what the hell..

 */

inline int

writen(fd, bptr, n)

	int fd;

	char *bptr;

	int n;

{

	int ret;

	int total;

	/* This should succeed most of the time */

	ret = send(fd, bptr, n,0);

	if (ret == n || ret <= 0)

	   return ret;

	/* Didn't write everything, go into the loop */

	total = ret;

	while (n > total) {

		ret = send(fd, bptr+total, n-total,0);

		if (ret <= 0)

		   return ret;

		total += ret;

	}

	return total;

}

/*

 * if_input - read() the tty, do "top level" processing (ie: check for any escapes),

 * and pass onto (*ttyp->if_input)

 *

 * XXXXX Any zeros arriving by themselves are NOT placed into the arriving packet.

 */

#define INBUFF_SIZE 2048 /* XXX */

void

if_input(ttyp)

	struct ttys *ttyp;

{

	u_char if_inbuff[INBUFF_SIZE];

	int if_n;

	DEBUG_CALL("if_input");

	DEBUG_ARG("ttyp = %lx", (long)ttyp);

	if_n = recv(ttyp->fd, (char *)if_inbuff, INBUFF_SIZE,0);

	DEBUG_MISC((dfd, " read %d bytes\n", if_n));

	if (if_n <= 0) {

		if (if_n == 0 || (errno != EINTR && errno != EAGAIN)) {

			if (ttyp->up)

			   link_up--;

			tty_detached(ttyp, 0);

		}

		return;

	}

	if (if_n == 1) {

		if (*if_inbuff == '0') {

			ttyp->ones = 0;

			if (++ttyp->zeros >= 5)

			   slirp_exit(0);

			return;

		}

		if (*if_inbuff == '1') {

			ttyp->zeros = 0;

			if (++ttyp->ones >= 5)

			   tty_detached(ttyp, 0);

			return;

		}

	}

	ttyp->ones = ttyp->zeros = 0;

	(*ttyp->if_input)(ttyp, if_inbuff, if_n);

}

#endif

/*

 * if_output: Queue packet into an output queue.

 * There are 2 output queue's, if_fastq and if_batchq.

 * Each output queue is a doubly linked list of double linked lists

 * of mbufs, each list belonging to one "session" (socket).  This

 * way, we can output packets fairly by sending one packet from each

 * session, instead of all the packets from one session, then all packets

 * from the next session, etc.  Packets on the if_fastq get absolute

 * priority, but if one session hogs the link, it gets "downgraded"

 * to the batchq until it runs out of packets, then it'll return

 * to the fastq (eg. if the user does an ls -alR in a telnet session,

 * it'll temporarily get downgraded to the batchq)

 */

void

if_output(so, ifm)

	struct socket *so;

	struct mbuf *ifm;

{

	struct mbuf *ifq;

	int on_fastq = 1;

	DEBUG_CALL("if_output");

	DEBUG_ARG("so = %lx", (long)so);

	DEBUG_ARG("ifm = %lx", (long)ifm);

	/*

	 * First remove the mbuf from m_usedlist,

	 * since we're gonna use m_next and m_prev ourselves

	 * XXX Shouldn't need this, gotta change dtom() etc.

	 */

	if (ifm->m_flags & M_USEDLIST) {

		remque(ifm);

		ifm->m_flags &= ~M_USEDLIST;

	}

	/*

	 * See if there's already a batchq list for this session.

	 * This can include an interactive session, which should go on fastq,

	 * but gets too greedy... hence it'll be downgraded from fastq to batchq.

	 * We mustn't put this packet back on the fastq (or we'll send it out of order)

	 * XXX add cache here?

	 */

	for (ifq = if_batchq.ifq_prev; ifq != &if_batchq; ifq = ifq->ifq_prev) {

		if (so == ifq->ifq_so) {

			/* A match! */

			ifm->ifq_so = so;

			ifs_insque(ifm, ifq->ifs_prev);

			goto diddit;

		}

	}

	/* No match, check which queue to put it on */

	if (so && (so->so_iptos & IPTOS_LOWDELAY)) {

		ifq = if_fastq.ifq_prev;

		on_fastq = 1;

		/*

		 * Check if this packet is a part of the last

		 * packet's session

		 */

		if (ifq->ifq_so == so) {

			ifm->ifq_so = so;

			ifs_insque(ifm, ifq->ifs_prev);

			goto diddit;

		}

	} else

		ifq = if_batchq.ifq_prev;

	/* Create a new doubly linked list for this session */

	ifm->ifq_so = so;

	ifs_init(ifm);

	insque(ifm, ifq);

diddit:

	++if_queued;

	if (so) {

		/* Update *_queued */

		so->so_queued++;

		so->so_nqueued++;

		/*

		 * Check if the interactive session should be downgraded to

		 * the batchq.  A session is downgraded if it has queued 6

		 * packets without pausing, and at least 3 of those packets

		 * have been sent over the link

		 * (XXX These are arbitrary numbers, probably not optimal..)

		 */

		if (on_fastq && ((so->so_nqueued >= 6) &&

				 (so->so_nqueued - so->so_queued) >= 3)) {

			/* Remove from current queue... */

			remque(ifm->ifs_next);

			/* ...And insert in the new.  That'll teach ya! */

			insque(ifm->ifs_next, &if_batchq);

		}

	}

#ifndef FULL_BOLT

	/*

	 * This prevents us from malloc()ing too many mbufs

	 */

	if (link_up) {

		/* if_start will check towrite */

		if_start();

	}

#endif

}

/*

 * Send a packet

 * We choose a packet based on it's position in the output queues;

 * If there are packets on the fastq, they are sent FIFO, before

 * everything else.  Otherwise we choose the first packet from the

 * batchq and send it.  the next packet chosen will be from the session

 * after this one, then the session after that one, and so on..  So,

 * for example, if there are 3 ftp session's fighting for bandwidth,

 * one packet will be sent from the first session, then one packet

 * from the second session, then one packet from the third, then back

 * to the first, etc. etc.

 */

void

if_start(void)

{

	struct mbuf *ifm, *ifqt;

	DEBUG_CALL("if_start");

	if (if_queued == 0)

	   return; /* Nothing to do */

 again:

        /* check if we can really output */

        if (!slirp_can_output())

            return;

	/*

	 * See which queue to get next packet from

	 * If there's something in the fastq, select it immediately

	 */

	if (if_fastq.ifq_next != &if_fastq) {

		ifm = if_fastq.ifq_next;

	} else {

		/* Nothing on fastq, see if next_m is valid */

		if (next_m != &if_batchq)

		   ifm = next_m;

		else

		   ifm = if_batchq.ifq_next;

		/* Set which packet to send on next iteration */

		next_m = ifm->ifq_next;

	}

	/* Remove it from the queue */

	ifqt = ifm->ifq_prev;

	remque(ifm);

	--if_queued;

	/* If there are more packets for this session, re-queue them */

	if (ifm->ifs_next != /* ifm->ifs_prev != */ ifm) {

		insque(ifm->ifs_next, ifqt);

		ifs_remque(ifm);

	}

	/* Update so_queued */

	if (ifm->ifq_so) {

		if (--ifm->ifq_so->so_queued == 0)

		   /* If there's no more queued, reset nqueued */

		   ifm->ifq_so->so_nqueued = 0;

	}

	/* Encapsulate the packet for sending */

        if_encap((uint8_t *)ifm->m_data, ifm->m_len);

        m_free(ifm);

	if (if_queued)

	   goto again;

}