238 lines
6.8 KiB
C
238 lines
6.8 KiB
C
/*
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* Copyright (c) 1995 Danny Gasparovski.
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*
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* Please read the file COPYRIGHT for the
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* terms and conditions of the copyright.
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*/
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#include <slirp.h>
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#include "qemu/timer.h"
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static void
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ifs_insque(struct mbuf *ifm, struct mbuf *ifmhead)
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{
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ifm->ifs_next = ifmhead->ifs_next;
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ifmhead->ifs_next = ifm;
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ifm->ifs_prev = ifmhead;
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ifm->ifs_next->ifs_prev = ifm;
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}
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static void
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ifs_remque(struct mbuf *ifm)
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{
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ifm->ifs_prev->ifs_next = ifm->ifs_next;
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ifm->ifs_next->ifs_prev = ifm->ifs_prev;
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}
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void
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if_init(Slirp *slirp)
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{
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slirp->if_fastq.ifq_next = slirp->if_fastq.ifq_prev = &slirp->if_fastq;
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slirp->if_batchq.ifq_next = slirp->if_batchq.ifq_prev = &slirp->if_batchq;
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slirp->next_m = &slirp->if_batchq;
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}
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/*
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* if_output: Queue packet into an output queue.
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* There are 2 output queue's, if_fastq and if_batchq.
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* Each output queue is a doubly linked list of double linked lists
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* of mbufs, each list belonging to one "session" (socket). This
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* way, we can output packets fairly by sending one packet from each
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* session, instead of all the packets from one session, then all packets
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* from the next session, etc. Packets on the if_fastq get absolute
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* priority, but if one session hogs the link, it gets "downgraded"
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* to the batchq until it runs out of packets, then it'll return
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* to the fastq (eg. if the user does an ls -alR in a telnet session,
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* it'll temporarily get downgraded to the batchq)
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*/
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void
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if_output(struct socket *so, struct mbuf *ifm)
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{
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Slirp *slirp = ifm->slirp;
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struct mbuf *ifq;
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int on_fastq = 1;
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DEBUG_CALL("if_output");
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DEBUG_ARG("so = %lx", (long)so);
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DEBUG_ARG("ifm = %lx", (long)ifm);
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/*
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* First remove the mbuf from m_usedlist,
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* since we're gonna use m_next and m_prev ourselves
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* XXX Shouldn't need this, gotta change dtom() etc.
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*/
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if (ifm->m_flags & M_USEDLIST) {
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remque(ifm);
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ifm->m_flags &= ~M_USEDLIST;
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}
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/*
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* See if there's already a batchq list for this session.
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* This can include an interactive session, which should go on fastq,
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* but gets too greedy... hence it'll be downgraded from fastq to batchq.
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* We mustn't put this packet back on the fastq (or we'll send it out of order)
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* XXX add cache here?
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*/
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for (ifq = slirp->if_batchq.ifq_prev; ifq != &slirp->if_batchq;
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ifq = ifq->ifq_prev) {
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if (so == ifq->ifq_so) {
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/* A match! */
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ifm->ifq_so = so;
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ifs_insque(ifm, ifq->ifs_prev);
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goto diddit;
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}
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}
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/* No match, check which queue to put it on */
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if (so && (so->so_iptos & IPTOS_LOWDELAY)) {
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ifq = slirp->if_fastq.ifq_prev;
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on_fastq = 1;
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/*
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* Check if this packet is a part of the last
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* packet's session
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*/
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if (ifq->ifq_so == so) {
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ifm->ifq_so = so;
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ifs_insque(ifm, ifq->ifs_prev);
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goto diddit;
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}
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} else {
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ifq = slirp->if_batchq.ifq_prev;
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/* Set next_m if the queue was empty so far */
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if (slirp->next_m == &slirp->if_batchq) {
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slirp->next_m = ifm;
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}
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}
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/* Create a new doubly linked list for this session */
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ifm->ifq_so = so;
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ifs_init(ifm);
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insque(ifm, ifq);
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diddit:
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if (so) {
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/* Update *_queued */
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so->so_queued++;
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so->so_nqueued++;
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/*
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* Check if the interactive session should be downgraded to
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* the batchq. A session is downgraded if it has queued 6
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* packets without pausing, and at least 3 of those packets
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* have been sent over the link
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* (XXX These are arbitrary numbers, probably not optimal..)
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*/
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if (on_fastq && ((so->so_nqueued >= 6) &&
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(so->so_nqueued - so->so_queued) >= 3)) {
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/* Remove from current queue... */
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remque(ifm->ifs_next);
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/* ...And insert in the new. That'll teach ya! */
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insque(ifm->ifs_next, &slirp->if_batchq);
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}
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}
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#ifndef FULL_BOLT
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/*
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* This prevents us from malloc()ing too many mbufs
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*/
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if_start(ifm->slirp);
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#endif
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}
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/*
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* Send a packet
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* We choose a packet based on it's position in the output queues;
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* If there are packets on the fastq, they are sent FIFO, before
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* everything else. Otherwise we choose the first packet from the
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* batchq and send it. the next packet chosen will be from the session
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* after this one, then the session after that one, and so on.. So,
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* for example, if there are 3 ftp session's fighting for bandwidth,
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* one packet will be sent from the first session, then one packet
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* from the second session, then one packet from the third, then back
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* to the first, etc. etc.
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*/
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void if_start(Slirp *slirp)
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{
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uint64_t now = qemu_get_clock_ns(rt_clock);
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bool from_batchq, next_from_batchq;
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struct mbuf *ifm, *ifm_next, *ifqt;
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DEBUG_CALL("if_start");
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if (slirp->if_start_busy) {
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return;
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}
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slirp->if_start_busy = true;
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if (slirp->if_fastq.ifq_next != &slirp->if_fastq) {
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ifm_next = slirp->if_fastq.ifq_next;
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next_from_batchq = false;
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} else if (slirp->next_m != &slirp->if_batchq) {
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/* Nothing on fastq, pick up from batchq via next_m */
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ifm_next = slirp->next_m;
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next_from_batchq = true;
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} else {
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ifm_next = NULL;
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}
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while (ifm_next) {
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ifm = ifm_next;
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from_batchq = next_from_batchq;
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ifm_next = ifm->ifq_next;
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if (ifm_next == &slirp->if_fastq) {
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/* No more packets in fastq, switch to batchq */
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ifm_next = slirp->next_m;
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next_from_batchq = true;
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}
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if (ifm_next == &slirp->if_batchq) {
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/* end of batchq */
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ifm_next = NULL;
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}
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/* Try to send packet unless it already expired */
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if (ifm->expiration_date >= now && !if_encap(slirp, ifm)) {
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/* Packet is delayed due to pending ARP resolution */
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continue;
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}
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if (ifm == slirp->next_m) {
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/* Set which packet to send on next iteration */
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slirp->next_m = ifm->ifq_next;
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}
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/* Remove it from the queue */
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ifqt = ifm->ifq_prev;
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remque(ifm);
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/* If there are more packets for this session, re-queue them */
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if (ifm->ifs_next != ifm) {
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struct mbuf *next = ifm->ifs_next;
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insque(next, ifqt);
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ifs_remque(ifm);
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if (!from_batchq) {
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/* Next packet in fastq is from the same session */
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ifm_next = next;
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next_from_batchq = false;
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} else if (slirp->next_m == &slirp->if_batchq) {
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/* Set next_m and ifm_next if the session packet is now the
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* only one on batchq */
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slirp->next_m = ifm_next = next;
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}
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}
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/* Update so_queued */
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if (ifm->ifq_so && --ifm->ifq_so->so_queued == 0) {
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/* If there's no more queued, reset nqueued */
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ifm->ifq_so->so_nqueued = 0;
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}
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m_free(ifm);
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}
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slirp->if_start_busy = false;
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}
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