qemu/slirp/if.c

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/*
* Copyright (c) 1995 Danny Gasparovski.
*
* Please read the file COPYRIGHT for the
* terms and conditions of the copyright.
*/
#include <slirp.h>
int if_mtu, if_mru;
int if_comp;
int if_maxlinkhdr;
int if_queued = 0; /* Number of packets queued so far */
int if_thresh = 10; /* Number of packets queued before we start sending
* (to prevent allocing too many mbufs) */
struct mbuf if_fastq; /* fast queue (for interactive data) */
struct mbuf if_batchq; /* queue for non-interactive data */
struct mbuf *next_m; /* Pointer to next mbuf to output */
#define ifs_init(ifm) ((ifm)->ifs_next = (ifm)->ifs_prev = (ifm))
void
ifs_insque(ifm, ifmhead)
struct mbuf *ifm, *ifmhead;
{
ifm->ifs_next = ifmhead->ifs_next;
ifmhead->ifs_next = ifm;
ifm->ifs_prev = ifmhead;
ifm->ifs_next->ifs_prev = ifm;
}
void
ifs_remque(ifm)
struct mbuf *ifm;
{
ifm->ifs_prev->ifs_next = ifm->ifs_next;
ifm->ifs_next->ifs_prev = ifm->ifs_prev;
}
void
if_init()
{
#if 0
/*
* Set if_maxlinkhdr to 48 because it's 40 bytes for TCP/IP,
* and 8 bytes for PPP, but need to have it on an 8byte boundary
*/
#ifdef USE_PPP
if_maxlinkhdr = 48;
#else
if_maxlinkhdr = 40;
#endif
#else
/* 2 for alignment, 14 for ethernet, 40 for TCP/IP */
if_maxlinkhdr = 2 + 14 + 40;
#endif
if_mtu = 1500;
if_mru = 1500;
if_comp = IF_AUTOCOMP;
if_fastq.ifq_next = if_fastq.ifq_prev = &if_fastq;
if_batchq.ifq_next = if_batchq.ifq_prev = &if_batchq;
// sl_compress_init(&comp_s);
next_m = &if_batchq;
}
#if 0
/*
* This shouldn't be needed since the modem is blocking and
* we don't expect any signals, but what the hell..
*/
inline int
writen(fd, bptr, n)
int fd;
char *bptr;
int n;
{
int ret;
int total;
/* This should succeed most of the time */
ret = send(fd, bptr, n,0);
if (ret == n || ret <= 0)
return ret;
/* Didn't write everything, go into the loop */
total = ret;
while (n > total) {
ret = send(fd, bptr+total, n-total,0);
if (ret <= 0)
return ret;
total += ret;
}
return total;
}
/*
* if_input - read() the tty, do "top level" processing (ie: check for any escapes),
* and pass onto (*ttyp->if_input)
*
* XXXXX Any zeros arriving by themselves are NOT placed into the arriving packet.
*/
#define INBUFF_SIZE 2048 /* XXX */
void
if_input(ttyp)
struct ttys *ttyp;
{
u_char if_inbuff[INBUFF_SIZE];
int if_n;
DEBUG_CALL("if_input");
DEBUG_ARG("ttyp = %lx", (long)ttyp);
if_n = recv(ttyp->fd, (char *)if_inbuff, INBUFF_SIZE,0);
DEBUG_MISC((dfd, " read %d bytes\n", if_n));
if (if_n <= 0) {
if (if_n == 0 || (errno != EINTR && errno != EAGAIN)) {
if (ttyp->up)
link_up--;
tty_detached(ttyp, 0);
}
return;
}
if (if_n == 1) {
if (*if_inbuff == '0') {
ttyp->ones = 0;
if (++ttyp->zeros >= 5)
slirp_exit(0);
return;
}
if (*if_inbuff == '1') {
ttyp->zeros = 0;
if (++ttyp->ones >= 5)
tty_detached(ttyp, 0);
return;
}
}
ttyp->ones = ttyp->zeros = 0;
(*ttyp->if_input)(ttyp, if_inbuff, if_n);
}
#endif
/*
* 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(so, ifm)
struct socket *so;
struct mbuf *ifm;
{
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 = if_batchq.ifq_prev; ifq != &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 = 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 = if_batchq.ifq_prev;
/* Create a new doubly linked list for this session */
ifm->ifq_so = so;
ifs_init(ifm);
insque(ifm, ifq);
diddit:
++if_queued;
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, &if_batchq);
}
}
#ifndef FULL_BOLT
/*
* This prevents us from malloc()ing too many mbufs
*/
if (link_up) {
/* if_start will check towrite */
if_start();
}
#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(void)
{
struct mbuf *ifm, *ifqt;
DEBUG_CALL("if_start");
if (if_queued == 0)
return; /* Nothing to do */
again:
/* check if we can really output */
if (!slirp_can_output())
return;
/*
* See which queue to get next packet from
* If there's something in the fastq, select it immediately
*/
if (if_fastq.ifq_next != &if_fastq) {
ifm = if_fastq.ifq_next;
} else {
/* Nothing on fastq, see if next_m is valid */
if (next_m != &if_batchq)
ifm = next_m;
else
ifm = if_batchq.ifq_next;
/* Set which packet to send on next iteration */
next_m = ifm->ifq_next;
}
/* Remove it from the queue */
ifqt = ifm->ifq_prev;
remque(ifm);
--if_queued;
/* If there are more packets for this session, re-queue them */
if (ifm->ifs_next != /* ifm->ifs_prev != */ ifm) {
insque(ifm->ifs_next, ifqt);
ifs_remque(ifm);
}
/* Update so_queued */
if (ifm->ifq_so) {
if (--ifm->ifq_so->so_queued == 0)
/* If there's no more queued, reset nqueued */
ifm->ifq_so->so_nqueued = 0;
}
/* Encapsulate the packet for sending */
if_encap(ifm->m_data, ifm->m_len);
m_free(ifm);
if (if_queued)
goto again;
}