diff options
Diffstat (limited to 'slirp/if.c')
| -rw-r--r-- | slirp/if.c | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/slirp/if.c b/slirp/if.c new file mode 100644 index 00000000..fb7acf87 --- /dev/null +++ b/slirp/if.c @@ -0,0 +1,237 @@ +/* + * 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; +} |