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/* SPDX-License-Identifier: BSD-3-Clause */
/*
* Copyright (c) 1995 Danny Gasparovski.
*/
#include "slirp.h"
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(Slirp *slirp)
{
slirp->if_fastq.qh_link = slirp->if_fastq.qh_rlink = &slirp->if_fastq;
slirp->if_batchq.qh_link = slirp->if_batchq.qh_rlink = &slirp->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(struct socket *so, struct mbuf *ifm)
{
Slirp *slirp = ifm->slirp;
M_DUP_DEBUG(slirp, ifm, 0, 0);
struct mbuf *ifq;
int on_fastq = 1;
DEBUG_CALL("if_output");
DEBUG_ARG("so = %p", so);
DEBUG_ARG("ifm = %p", 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?
*/
if (so) {
for (ifq = (struct mbuf *)slirp->if_batchq.qh_rlink;
(struct quehead *)ifq != &slirp->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 = (struct mbuf *)slirp->if_fastq.qh_rlink;
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 = (struct mbuf *)slirp->if_batchq.qh_rlink;
}
/* Create a new doubly linked list for this session */
ifm->ifq_so = so;
ifs_init(ifm);
insque(ifm, ifq);
diddit:
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, &slirp->if_batchq);
}
}
/*
* This prevents us from malloc()ing too many mbufs
*/
if_start(ifm->slirp);
}
/*
* Send one packet from each session.
* If there are packets on the fastq, they are sent FIFO, before
* everything else. Then we choose the first packet from each
* batchq session (socket) and send it.
* For example, if there are 3 ftp sessions 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.
*/
void if_start(Slirp *slirp)
{
uint64_t now = slirp->cb->clock_get_ns(slirp->opaque);
bool from_batchq = false;
struct mbuf *ifm, *ifm_next, *ifqt;
DEBUG_VERBOSE_CALL("if_start");
if (slirp->if_start_busy) {
return;
}
slirp->if_start_busy = true;
struct mbuf *batch_head = NULL;
if (slirp->if_batchq.qh_link != &slirp->if_batchq) {
batch_head = (struct mbuf *)slirp->if_batchq.qh_link;
}
if (slirp->if_fastq.qh_link != &slirp->if_fastq) {
ifm_next = (struct mbuf *)slirp->if_fastq.qh_link;
} else if (batch_head) {
/* Nothing on fastq, pick up from batchq */
ifm_next = batch_head;
from_batchq = true;
} else {
ifm_next = NULL;
}
while (ifm_next) {
ifm = ifm_next;
ifm_next = ifm->ifq_next;
if ((struct quehead *)ifm_next == &slirp->if_fastq) {
/* No more packets in fastq, switch to batchq */
ifm_next = batch_head;
from_batchq = true;
}
if ((struct quehead *)ifm_next == &slirp->if_batchq) {
/* end of batchq */
ifm_next = NULL;
}
/* Try to send packet unless it already expired */
if (ifm->expiration_date >= now && !if_encap(slirp, ifm)) {
/* Packet is delayed due to pending ARP or NDP resolution */
continue;
}
/* Remove it from the queue */
ifqt = ifm->ifq_prev;
remque(ifm);
/* If there are more packets for this session, re-queue them */
if (ifm->ifs_next != ifm) {
struct mbuf *next = ifm->ifs_next;
insque(next, ifqt);
ifs_remque(ifm);
if (!from_batchq) {
ifm_next = next;
}
}
/* Update so_queued */
if (ifm->ifq_so && --ifm->ifq_so->so_queued == 0) {
/* If there's no more queued, reset nqueued */
ifm->ifq_so->so_nqueued = 0;
}
m_free(ifm);
}
slirp->if_start_busy = false;
}
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