| /* |
| * 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 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(Slirp *slirp) |
| { |
| uint64_t now = qemu_get_clock_ns(rt_clock); |
| 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; |
| } |
