if.c revision 83ecf7d6751255e03c9ed8b75fc23676322c9143
/*
* Copyright (c) 1995 Danny Gasparovski.
*
* Please read the file COPYRIGHT for the
* terms and conditions of the copyright.
*/
#include <slirp.h>
#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(PNATState pData)
{
#ifdef VBOX_WITH_SIMPLIFIED_SLIRP_SYNC
/* 14 for ethernet */
if_maxlinkhdr = 14;
#else
/* 2 for alignment, 14 for ethernet, 40 for TCP/IP */
if_maxlinkhdr = 2 + 14 + 40;
#endif
if_queued = 0;
if_thresh = 10;
if_mtu = 1500;
if_mru = 1500;
if_comp = IF_AUTOCOMP;
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_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(PNATState pData, 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(pData, 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(pData, 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(pData, ifm->ifs_next);
/* ...And insert in the new. That'll teach ya! */
insque(pData, 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(pData);
}
#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(PNATState pData)
{
struct mbuf *ifm, *ifqt;
DEBUG_CALL("if_start");
if (!if_queued)
return; /* Nothing to do */
for (;;)
{
/* check if we can really output */
if (!slirp_can_output(pData->pvUser))
{
Log(("if_start: can't send\n"));
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(pData, ifm);
--if_queued;
/* If there are more packets for this session, re-queue them */
if (ifm->ifs_next != /* ifm->ifs_prev != */ ifm)
{
insque(pData, 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;
}
#ifdef VBOX_WITH_SIMPLIFIED_SLIRP_SYNC
if_encap(pData, ETH_P_IP, ifm);
#else
if_encap(pData, mtod(ifm, uint8_t *), ifm->m_len);
m_free(pData, ifm);
#endif
if (!if_queued)
return;
}
}