--- /dev/null
+/*
+ * Copyright (c) 1995 Danny Gasparovski.
+ *
+ * Please read the file COPYRIGHT for the
+ * terms and conditions of the copyright.
+ */
+
+#include <slirp.h>
+#include "qemu/timer.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.ifq_next = slirp->if_fastq.ifq_prev = &slirp->if_fastq;
+ slirp->if_batchq.ifq_next = slirp->if_batchq.ifq_prev = &slirp->if_batchq;
+ slirp->next_m = &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;
+ 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 = slirp->if_batchq.ifq_prev; 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 = slirp->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 = slirp->if_batchq.ifq_prev;
+ /* Set next_m if the queue was empty so far */
+ if (slirp->next_m == &slirp->if_batchq) {
+ slirp->next_m = ifm;
+ }
+ }
+
+ /* 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);
+ }
+ }
+
+#ifndef FULL_BOLT
+ /*
+ * This prevents us from malloc()ing too many mbufs
+ */
+ if_start(ifm->slirp);
+#endif
+}
+
+/*
+ * Send a packet
+ * We choose a packet based on its 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(Slirp *slirp)
+{
+ uint64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
+ bool from_batchq, next_from_batchq;
+ struct mbuf *ifm, *ifm_next, *ifqt;
+
+ DEBUG_CALL("if_start");
+
+ if (slirp->if_start_busy) {
+ return;
+ }
+ slirp->if_start_busy = true;
+
+ if (slirp->if_fastq.ifq_next != &slirp->if_fastq) {
+ ifm_next = slirp->if_fastq.ifq_next;
+ next_from_batchq = false;
+ } else if (slirp->next_m != &slirp->if_batchq) {
+ /* Nothing on fastq, pick up from batchq via next_m */
+ ifm_next = slirp->next_m;
+ next_from_batchq = true;
+ } else {
+ ifm_next = NULL;
+ }
+
+ while (ifm_next) {
+ ifm = ifm_next;
+ from_batchq = next_from_batchq;
+
+ ifm_next = ifm->ifq_next;
+ if (ifm_next == &slirp->if_fastq) {
+ /* No more packets in fastq, switch to batchq */
+ ifm_next = slirp->next_m;
+ next_from_batchq = true;
+ }
+ if (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 resolution */
+ continue;
+ }
+
+ if (ifm == slirp->next_m) {
+ /* Set which packet to send on next iteration */
+ slirp->next_m = ifm->ifq_next;
+ }
+
+ /* 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) {
+ /* Next packet in fastq is from the same session */
+ ifm_next = next;
+ next_from_batchq = false;
+ } else if (slirp->next_m == &slirp->if_batchq) {
+ /* Set next_m and ifm_next if the session packet is now the
+ * only one on batchq */
+ slirp->next_m = 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;
+}
Code Review / kvmfornfv.git / blobdiff