/* * 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; }