/* $NetBSD: if_sl.c,v 1.136 2022/10/26 23:42:42 riastradh Exp $ */

/* $NetBSD: if_sl.c,v 1.136 2022/10/26 23:42:42 riastradh Exp $ */

/*
* Copyright (c) 1987, 1989, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)if_sl.c 8.9 (Berkeley) 1/9/95
*/

/*
* Serial Line interface
*
* Rick Adams
* Center for Seismic Studies
* 1300 N 17th Street, Suite 1450
* Arlington, Virginia 22209
* (703)276-7900
* [email protected]
* seismo!rick
*
* Pounded on heavily by Chris Torek ([email protected], umcp-cs!chris).
* N.B.: this belongs in netinet, not net, the way it stands now.
* Should have a link-layer type designation, but wouldn't be
* backwards-compatible.
*
* Converted to 4.3BSD Beta by Chris Torek.
* Other changes made at Berkeley, based in part on code by Kirk Smith.
* W. Jolitz added slip abort.
*
* Hacked almost beyond recognition by Van Jacobson ([email protected]).
* Added priority queuing for "interactive" traffic; hooks for TCP
* header compression; ICMP filtering (at 2400 baud, some cretin
* pinging you can use up all your bandwidth). Made low clist behavior
* more robust and slightly less likely to hang serial line.
* Sped up a bunch of things.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_sl.c,v 1.136 2022/10/26 23:42:42 riastradh Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#endif

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/buf.h>
#include <sys/dkstat.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/file.h>
#include <sys/conf.h>
#include <sys/tty.h>
#include <sys/kernel.h>
#include <sys/socketvar.h>
#if __NetBSD__
#include <sys/systm.h>
#include <sys/kauth.h>
#endif
#include <sys/cpu.h>
#include <sys/intr.h>
#include <sys/device.h>
#include <sys/module.h>

#include <net/if.h>
#include <net/if_types.h>
#include <net/route.h>

#ifdef INET
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#endif

#include <net/slcompress.h>
#include <net/if_slvar.h>
#include <net/slip.h>
#include <net/ppp_defs.h>
#include <net/if_ppp.h>

#include <sys/time.h>
#include <net/bpf.h>

#include "ioconf.h"

/*
* SLMAX is a hard limit on input packet size. To simplify the code
* and improve performance, we require that packets fit in an mbuf
* cluster, and if we get a compressed packet, there's enough extra
* room to expand the header into a max length tcp/ip header (128
* bytes). So, SLMAX can be at most
* MCLBYTES - 128
*
* SLMTU is a hard limit on output packet size. To insure good
* interactive response, SLMTU wants to be the smallest size that
* amortizes the header cost. (Remember that even with
* type-of-service queuing, we have to wait for any in-progress
* packet to finish. I.e., we wait, on the average, 1/2 * mtu /
* cps, where cps is the line speed in characters per second.
* E.g., 533ms wait for a 1024 byte MTU on a 9600 baud line. The
* average compressed header size is 6-8 bytes so any MTU > 90
* bytes will give us 90% of the line bandwidth. A 100ms wait is
* tolerable (500ms is not), so want an MTU around 296. (Since TCP
* will send 256 byte segments (to allow for 40 byte headers), the
* typical packet size on the wire will be around 260 bytes). In
* 4.3tahoe+ systems, we can set an MTU in a route so we do that &
* leave the interface MTU relatively high (so we don't IP fragment
* when acting as a gateway to someone using a stupid MTU).
*
* Similar considerations apply to SLIP_HIWAT: It's the amount of
* data that will be queued 'downstream' of us (i.e., in clists
* waiting to be picked up by the tty output interrupt). If we
* queue a lot of data downstream, it's immune to our t.o.s. queuing.
* E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
* telnet/ftp will see a 1 sec wait, independent of the mtu (the
* wait is dependent on the ftp window size but that's typically
* 1k - 4k). So, we want SLIP_HIWAT just big enough to amortize
* the cost (in idle time on the wire) of the tty driver running
* off the end of its clists & having to call back slstart for a
* new packet. For a tty interface with any buffering at all, this
* cost will be zero. Even with a totally brain dead interface (like
* the one on a typical workstation), the cost will be <= 1 character
* time. So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
* at most 1% while maintaining good interactive response.
*/
#define BUFOFFSET (128+sizeof(struct ifnet **)+SLIP_HDRLEN)
#define SLMAX (MCLBYTES - BUFOFFSET)
#define SLBUFSIZE (SLMAX + BUFOFFSET)
#ifndef SLMTU
#define SLMTU 296
#endif
#if (SLMTU < 3)
#error SLMTU way too small.
#endif
#define SLIP_HIWAT roundup(50, TTROUND)
#ifndef __NetBSD__ /* XXX - cgd */
#define CLISTRESERVE 1024 /* Can't let clists get too low */
#endif /* !__NetBSD__ */

/*
* SLIP ABORT ESCAPE MECHANISM:
* (inspired by HAYES modem escape arrangement)
* 1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
* within window time signals a "soft" exit from slip mode by remote end
* if the IFF_DEBUG flag is on.
*/
#define ABT_ESC '\033' /* can't be t_intr - distant host must know it*/
#define ABT_IDLE 1 /* in seconds - idle before an escape */
#define ABT_COUNT 3 /* count of escapes for abort */
#define ABT_WINDOW (ABT_COUNT*2+2) /* in seconds - time to count */

static int sl_clone_create(struct if_clone *, int);
static int sl_clone_destroy(struct ifnet *);

static LIST_HEAD(, sl_softc) sl_softc_list;

struct if_clone sl_cloner =
IF_CLONE_INITIALIZER("sl", sl_clone_create, sl_clone_destroy);

#define FRAME_END 0xc0 /* Frame End */
#define FRAME_ESCAPE 0xdb /* Frame Esc */
#define TRANS_FRAME_END 0xdc /* transposed frame end */
#define TRANS_FRAME_ESCAPE 0xdd /* transposed frame esc */

static void slintr(void *);

static int slcreate(struct sl_softc *);
static struct mbuf *sl_btom(struct sl_softc *, int);

static int slclose(struct tty *, int);
static int slinput(int, struct tty *);
static int slioctl(struct ifnet *, u_long, void *);
static int slopen(dev_t, struct tty *);
static int sloutput(struct ifnet *, struct mbuf *, const struct sockaddr *,
const struct rtentry *);
static int slstart(struct tty *);
static int sltioctl(struct tty *, u_long, void *, int, struct lwp *);

static struct linesw slip_disc = {
.l_name = "slip",
.l_open = slopen,
.l_close = slclose,
.l_read = ttyerrio,
.l_write = ttyerrio,
.l_ioctl = sltioctl,
.l_rint = slinput,
.l_start = slstart,
.l_modem = nullmodem,
.l_poll = ttyerrpoll
};

void
slattach(int n __unused)
{

/*
* Nothing to do here, initialization is handled by the
* module initialization code in slinit() below).
*/
}

static void
slinit(void)
{

if (ttyldisc_attach(&slip_disc) != 0)
panic("%s", __func__);
LIST_INIT(&sl_softc_list);
if_clone_attach(&sl_cloner);
}

static int
sldetach(void)
{
int error = 0;

if (!LIST_EMPTY(&sl_softc_list))
error = EBUSY;

if (error == 0)
error = ttyldisc_detach(&slip_disc);

if (error == 0)
if_clone_detach(&sl_cloner);

return error;
}

static int
sl_clone_create(struct if_clone *ifc, int unit)
{
struct sl_softc *sc;

sc = malloc(sizeof(*sc), M_DEVBUF, M_WAIT|M_ZERO);
sc->sc_unit = unit;
if_initname(&sc->sc_if, ifc->ifc_name, unit);
sc->sc_if.if_softc = sc;
sc->sc_if.if_mtu = SLMTU;
sc->sc_if.if_flags = IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
sc->sc_if.if_type = IFT_SLIP;
sc->sc_if.if_ioctl = slioctl;
sc->sc_if.if_output = sloutput;
sc->sc_if.if_dlt = DLT_SLIP;
IFQ_SET_MAXLEN(&sc->sc_fastq, 32);
IFQ_LOCK_INIT(&sc->sc_fastq);
IFQ_SET_READY(&sc->sc_if.if_snd);
if_attach(&sc->sc_if);
if_alloc_sadl(&sc->sc_if);
bpf_attach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
LIST_INSERT_HEAD(&sl_softc_list, sc, sc_iflist);
return 0;
}

static int
sl_clone_destroy(struct ifnet *ifp)
{
struct sl_softc *sc = (struct sl_softc *)ifp->if_softc;

if (sc->sc_ttyp != NULL)
return EBUSY; /* Not removing it */

LIST_REMOVE(sc, sc_iflist);

bpf_detach(ifp);
if_detach(ifp);

IFQ_LOCK_DESTROY(&sc->sc_fastq);

free(sc, M_DEVBUF);
return 0;
}

static int
slcreate(struct sl_softc *sc)
{

if (sc->sc_mbuf == NULL) {
sc->sc_mbuf = m_gethdr(M_WAIT, MT_DATA);
m_clget(sc->sc_mbuf, M_WAIT);
}
sc->sc_ep = (u_char *)sc->sc_mbuf->m_ext.ext_buf +
sc->sc_mbuf->m_ext.ext_size;
sc->sc_mp = sc->sc_pktstart = (u_char *)sc->sc_mbuf->m_ext.ext_buf +
BUFOFFSET;

#ifdef INET
sl_compress_init(&sc->sc_comp);
#endif

return 1;
}

/*
* Line specific open routine.
* Attach the given tty to the first available sl unit.
*/
/* ARGSUSED */
static int
slopen(dev_t dev, struct tty *tp)
{
struct lwp *l = curlwp; /* XXX */
struct sl_softc *sc;
int error;

error = kauth_authorize_network(l->l_cred, KAUTH_NETWORK_INTERFACE_SLIP,
KAUTH_REQ_NETWORK_INTERFACE_SLIP_ADD, NULL, NULL, NULL);
if (error)
return error;

if (tp->t_linesw == &slip_disc)
return 0;

LIST_FOREACH(sc, &sl_softc_list, sc_iflist)
if (sc->sc_ttyp == NULL) {
sc->sc_si = softint_establish(SOFTINT_NET,
slintr, sc);
if (sc->sc_si == NULL)
return ENOMEM;
if (slcreate(sc) == 0) {
softint_disestablish(sc->sc_si);
return ENOBUFS;
}
tp->t_sc = (void *)sc;
sc->sc_ttyp = tp;
sc->sc_if.if_baudrate = tp->t_ospeed;
ttylock(tp);
tp->t_state |= TS_ISOPEN | TS_XCLUDE;
ttyflush(tp, FREAD | FWRITE);
/*
* make sure tty output queue is large enough
* to hold a full-sized packet (including frame
* end, and a possible extra frame end). full-sized
* packet occupies a max of 2*SLMAX bytes (because
* of possible escapes), and add two on for frame
* ends.
*/
if (tp->t_outq.c_cn < 2 * SLMAX + 2) {
sc->sc_oldbufsize = tp->t_outq.c_cn;
sc->sc_oldbufquot = tp->t_outq.c_cq != 0;

clfree(&tp->t_outq);
ttyunlock(tp);
error = clalloc(&tp->t_outq, 2 * SLMAX + 2, 0);
if (error) {
softint_disestablish(sc->sc_si);
/*
* clalloc() might return -1 which
* is no good, so we need to return
* something else.
*/
return ENOMEM; /* XXX ?! */
}
} else {
sc->sc_oldbufsize = sc->sc_oldbufquot = 0;
ttyunlock(tp);
}
return 0;
}
return ENXIO;
}

/*
* Line specific close routine.
* Detach the tty from the sl unit.
*/
static int
slclose(struct tty *tp, int flag)
{
struct sl_softc *sc;
int s;

ttywflush(tp);
sc = tp->t_sc;

if (sc != NULL) {
softint_disestablish(sc->sc_si);
s = splnet();
if_down(&sc->sc_if);
IF_PURGE(&sc->sc_fastq);
splx(s);

s = spltty();
ttyldisc_release(tp->t_linesw);
tp->t_linesw = ttyldisc_default();
tp->t_state = 0;

sc->sc_ttyp = NULL;
tp->t_sc = NULL;

m_freem(sc->sc_mbuf);
sc->sc_mbuf = NULL;
sc->sc_ep = sc->sc_mp = sc->sc_pktstart = NULL;
IF_PURGE(&sc->sc_inq);

/*
* If necessary, install a new outq buffer of the
* appropriate size.
*/
if (sc->sc_oldbufsize != 0) {
clfree(&tp->t_outq);
clalloc(&tp->t_outq, sc->sc_oldbufsize,
sc->sc_oldbufquot);
}
splx(s);
}

return 0;
}

/*
* Line specific (tty) ioctl routine.
* Provide a way to get the sl unit number.
*/
/* ARGSUSED */
static int
sltioctl(struct tty *tp, u_long cmd, void *data, int flag,
struct lwp *l)
{
struct sl_softc *sc = (struct sl_softc *)tp->t_sc;

/*
* XXX
* This function can be called without KERNEL_LOCK when caller's
* struct cdevsw is set D_MPSAFE. Is KERNEL_LOCK required?
*/

switch (cmd) {
case SLIOCGUNIT:
*(int *)data = sc->sc_unit; /* XXX */
break;

default:
return EPASSTHROUGH;
}
return 0;
}

/*
* Queue a packet. Start transmission if not active.
* Compression happens in slintr(); if we do it here, IP TOS
* will cause us to not compress "background" packets, because
* ordering gets trashed. It can be done for all packets in slintr().
*/
static int
sloutput(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
const struct rtentry *rtp)
{
struct sl_softc *sc = ifp->if_softc;
struct ip *ip;
struct ifqueue *ifq = NULL;
int s, error;

IFQ_CLASSIFY(&ifp->if_snd, m, dst->sa_family);

/*
* `Cannot happen' (see slioctl). Someday we will extend
* the line protocol to support other address families.
*/
if (dst->sa_family != AF_INET) {
printf("%s: af%d not supported\n", sc->sc_if.if_xname,
dst->sa_family);
m_freem(m);
if_statinc(&sc->sc_if, if_noproto);
return EAFNOSUPPORT;
}

if (sc->sc_ttyp == NULL) {
m_freem(m);
return ENETDOWN; /* sort of */
}
if ((sc->sc_ttyp->t_state & TS_CARR_ON) == 0 &&
(sc->sc_ttyp->t_cflag & CLOCAL) == 0) {
m_freem(m);
printf("%s: no carrier and not local\n", sc->sc_if.if_xname);
return EHOSTUNREACH;
}
ip = mtod(m, struct ip *);
#ifdef INET
if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
m_freem(m);
return ENETRESET; /* XXX ? */
}
#endif

s = spltty();
if (sc->sc_oqlen && sc->sc_ttyp->t_outq.c_cc == sc->sc_oqlen) {
struct bintime bt;

/* if output's been stalled for too long, and restart */
getbinuptime(&bt);
bintime_sub(&bt, &sc->sc_lastpacket);
if (bt.sec > 0) {
sc->sc_otimeout++;
slstart(sc->sc_ttyp);
}
}
splx(s);

s = splnet();
#ifdef INET
if ((ip->ip_tos & IPTOS_LOWDELAY) != 0)
ifq = &sc->sc_fastq;
#endif
if ((error = ifq_enqueue2(ifp, ifq, m)) != 0) {
splx(s);
return error;
}
getbinuptime(&sc->sc_lastpacket);
splx(s);

s = spltty();
if ((sc->sc_oqlen = sc->sc_ttyp->t_outq.c_cc) == 0)
slstart(sc->sc_ttyp);
splx(s);

return 0;
}

/*
* Start output on interface. Get another datagram
* to send from the interface queue and map it to
* the interface before starting output.
*/
static int
slstart(struct tty *tp)
{
struct sl_softc *sc = tp->t_sc;

/*
* If there is more in the output queue, just send it now.
* We are being called in lieu of ttstart and must do what
* it would.
*/
if (tp->t_outq.c_cc != 0) {
(*tp->t_oproc)(tp);
if (tp->t_outq.c_cc > SLIP_HIWAT)
return 0;
}

/*
* This happens briefly when the line shuts down.
*/
if (sc == NULL)
return 0;
softint_schedule(sc->sc_si);
return 0;
}

/*
* Copy data buffer to mbuf chain; add ifnet pointer.
*/
static struct mbuf *
sl_btom(struct sl_softc *sc, int len)
{
struct mbuf *m;

/*
* Allocate a new input buffer and swap.
*/
m = sc->sc_mbuf;
MGETHDR(sc->sc_mbuf, M_DONTWAIT, MT_DATA);
if (sc->sc_mbuf == NULL) {
sc->sc_mbuf = m;
return NULL;
}
MCLGET(sc->sc_mbuf, M_DONTWAIT);
if ((sc->sc_mbuf->m_flags & M_EXT) == 0) {
m_freem(sc->sc_mbuf);
sc->sc_mbuf = m;
return NULL;
}
sc->sc_ep = (u_char *)sc->sc_mbuf->m_ext.ext_buf +
sc->sc_mbuf->m_ext.ext_size;

m->m_data = sc->sc_pktstart;

m->m_pkthdr.len = m->m_len = len;
m_set_rcvif(m, &sc->sc_if);
return m;
}

/*
* tty interface receiver interrupt.
*/
static int
slinput(int c, struct tty *tp)
{
struct sl_softc *sc;
struct mbuf *m;
int len;

tk_nin++;
sc = (struct sl_softc *)tp->t_sc;
if (sc == NULL)
return 0;
if ((c & TTY_ERRORMASK) || ((tp->t_state & TS_CARR_ON) == 0 &&
(tp->t_cflag & CLOCAL) == 0)) {
sc->sc_flags |= SC_ERROR;
return 0;
}
c &= TTY_CHARMASK;

if_statinc(&sc->sc_if, if_ibytes);

if (sc->sc_if.if_flags & IFF_DEBUG) {
if (c == ABT_ESC) {
/*
* If we have a previous abort, see whether
* this one is within the time limit.
*/
if (sc->sc_abortcount &&
time_second >= sc->sc_starttime + ABT_WINDOW)
sc->sc_abortcount = 0;
/*
* If we see an abort after "idle" time, count it;
* record when the first abort escape arrived.
*/
if (time_second >= sc->sc_lasttime + ABT_IDLE) {
if (++sc->sc_abortcount == 1)
sc->sc_starttime = time_second;
if (sc->sc_abortcount >= ABT_COUNT) {
slclose(tp, 0);
return 0;
}
}
} else
sc->sc_abortcount = 0;
sc->sc_lasttime = time_second;
}

switch (c) {

case TRANS_FRAME_ESCAPE:
if (sc->sc_escape)
c = FRAME_ESCAPE;
break;

case TRANS_FRAME_END:
if (sc->sc_escape)
c = FRAME_END;
break;

case FRAME_ESCAPE:
sc->sc_escape = 1;
return 0;

case FRAME_END:
if (sc->sc_flags & SC_ERROR) {
sc->sc_flags &= ~SC_ERROR;
goto newpack;
}
len = sc->sc_mp - sc->sc_pktstart;
if (len < 3)
/* less than min length packet - ignore */
goto newpack;

m = sl_btom(sc, len);
if (m == NULL)
goto error;

IF_ENQUEUE(&sc->sc_inq, m);
softint_schedule(sc->sc_si);
goto newpack;
}
if (sc->sc_mp < sc->sc_ep) {
*sc->sc_mp++ = c;
sc->sc_escape = 0;
return 0;
}

/* can't put lower; would miss an extra frame */
sc->sc_flags |= SC_ERROR;

error:
if_statinc(&sc->sc_if, if_ierrors);
newpack:
sc->sc_mp = sc->sc_pktstart = (u_char *)sc->sc_mbuf->m_ext.ext_buf +
BUFOFFSET;
sc->sc_escape = 0;

return 0;
}

static void
slintr(void *arg)
{
struct sl_softc *sc = arg;
struct tty *tp = sc->sc_ttyp;
struct mbuf *m, *n;
int s, len;
u_char *pktstart;
u_char chdr[CHDR_LEN];

KASSERT(tp != NULL);

/*
* Output processing loop.
*/
mutex_enter(softnet_lock);
for (;;) {
struct mbuf *m2;
struct mbuf *bpf_m;

/*
* Do not remove the packet from the queue if it
* doesn't look like it will fit into the current
* serial output queue. With a packet full of
* escapes, this could be as bad as MTU*2+2.
*/
s = spltty();
if (tp->t_outq.c_cn - tp->t_outq.c_cc <
2 * sc->sc_if.if_mtu + 2) {
splx(s);
break;
}
splx(s);

/*
* Get a packet and send it to the interface.
*/
s = splnet();
IF_DEQUEUE(&sc->sc_fastq, m);
if (m)
if_statinc(&sc->sc_if, if_omcasts); /* XXX */
else
IFQ_DEQUEUE(&sc->sc_if.if_snd, m);
splx(s);

if (m == NULL)
break;

/*
* We do the header compression here rather than in
* sloutput() because the packets will be out of order
* if we are using TOS queueing, and the connection
* ID compression will get munged when this happens.
*/
if (sc->sc_if.if_bpf) {
/*
* We need to save the TCP/IP header before
* it's compressed. To avoid complicated
* code, we just make a deep copy of the
* entire packet (since this is a serial
* line, packets should be short and/or the
* copy should be negligible cost compared
* to the packet transmission time).
*/
bpf_m = m_dup(m, 0, M_COPYALL, M_DONTWAIT);
} else
bpf_m = NULL;
#ifdef INET
struct ip *ip;
if ((ip = mtod(m, struct ip *))->ip_p == IPPROTO_TCP) {
if (sc->sc_if.if_flags & SC_COMPRESS)
*mtod(m, u_char *) |=
sl_compress_tcp(m, ip, &sc->sc_comp, 1);
}
#endif
if (bpf_m)
bpf_mtap_sl_out(&sc->sc_if, mtod(m, u_char *), bpf_m);
getbinuptime(&sc->sc_lastpacket);

s = spltty();

/*
* The extra FRAME_END will start up a new packet,
* and thus will flush any accumulated garbage. We
* do this whenever the line may have been idle for
* some time.
*/
if (tp->t_outq.c_cc == 0) {
if_statinc(&sc->sc_if, if_obytes);
(void)putc(FRAME_END, &tp->t_outq);
}

while (m) {
u_char *bp, *cp, *ep;

bp = cp = mtod(m, u_char *);
ep = cp + m->m_len;
while (cp < ep) {
/*
* Find out how many bytes in the
* string we can handle without
* doing something special.
*/
while (cp < ep) {
switch (*cp++) {
case FRAME_ESCAPE:
case FRAME_END:
cp--;
goto out;
}
}
out:
if (cp > bp) {
/*
* Put N characters at once
* into the tty output queue.
*/
if (b_to_q(bp, cp - bp, &tp->t_outq))
break;
if_statadd(&sc->sc_if, if_obytes,
cp - bp);
}
/*
* If there are characters left in
* the mbuf, the first one must be
* special.. Put it out in a different
* form.
*/
if (cp < ep) {
if (putc(FRAME_ESCAPE, &tp->t_outq))
break;
if (putc(*cp++ == FRAME_ESCAPE ?
TRANS_FRAME_ESCAPE :
TRANS_FRAME_END,
&tp->t_outq)) {
(void)unputc(&tp->t_outq);
break;
}
if_statadd(&sc->sc_if, if_obytes, 2);
}
bp = cp;
}
m = m2 = m_free(m);
}

if (putc(FRAME_END, &tp->t_outq)) {
/*
* Not enough room. Remove a char to make
* room and end the packet normally. If
* you get many collisions (more than one
* or two a day), you probably do not have
* enough clists and you should increase
* "nclist" in param.c
*/
(void)unputc(&tp->t_outq);
(void)putc(FRAME_END, &tp->t_outq);
if_statinc(&sc->sc_if, if_collisions);
} else {
if_statadd2(&sc->sc_if, if_obytes, 1, if_opackets, 1);
}

/*
* We now have characters in the output queue,
* kick the serial port.
*/
(*tp->t_oproc)(tp);
splx(s);
}

/*
* Input processing loop.
*/
for (;;) {
s = spltty();
IF_DEQUEUE(&sc->sc_inq, m);
splx(s);
if (m == NULL)
break;
pktstart = mtod(m, u_char *);
len = m->m_pkthdr.len;
if (sc->sc_if.if_bpf) {
/*
* Save the compressed header, so we
* can tack it on later. Note that we
* will end up copying garbage in some
* cases but this is okay. We remember
* where the buffer started so we can
* compute the new header length.
*/
memcpy(chdr, pktstart, CHDR_LEN);
}
#ifdef INET
u_char c;
if ((c = (*pktstart & 0xf0)) != (IPVERSION << 4)) {
if (c & 0x80)
c = TYPE_COMPRESSED_TCP;
else if (c == TYPE_UNCOMPRESSED_TCP)
*pktstart &= 0x4f; /* XXX */
/*
* We've got something that's not an IP
* packet. If compression is enabled,
* try to decompress it. Otherwise, if
* `auto-enable' compression is on and
* it's a reasonable packet, decompress
* it and then enable compression.
* Otherwise, drop it.
*/
if (sc->sc_if.if_flags & SC_COMPRESS) {
len = sl_uncompress_tcp(&pktstart, len,
(u_int)c, &sc->sc_comp);
if (len <= 0) {
m_freem(m);
continue;
}
} else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
len = sl_uncompress_tcp(&pktstart, len,
(u_int)c, &sc->sc_comp);
if (len <= 0) {
m_freem(m);
continue;
}
sc->sc_if.if_flags |= SC_COMPRESS;
} else {
m_freem(m);
continue;
}
}
#endif
m->m_data = (void *) pktstart;
m->m_pkthdr.len = m->m_len = len;
if (sc->sc_if.if_bpf) {
bpf_mtap_sl_in(&sc->sc_if, chdr, &m);
if (m == NULL)
continue;
}
/*
* If the packet will fit into a single
* header mbuf, try to copy it into one,
* to save memory.
*/
if ((m->m_pkthdr.len < MHLEN) &&
(n = m_gethdr(M_DONTWAIT, MT_DATA))) {
int pktlen;

pktlen = m->m_pkthdr.len;
m_move_pkthdr(n, m);
memcpy(mtod(n, void *), mtod(m, void *), pktlen);
n->m_len = m->m_len;
m_freem(m);
m = n;
}

if_statinc(&sc->sc_if, if_ipackets);
getbinuptime(&sc->sc_lastpacket);

#ifdef INET
s = splnet();
if (__predict_false(!pktq_enqueue(ip_pktq, m, 0))) {
if_statadd2(&sc->sc_if, if_ierrors, 1, if_iqdrops, 1);
m_freem(m);
}
splx(s);
#endif
}
mutex_exit(softnet_lock);
}

/*
* Process an ioctl request.
*/
static int
slioctl(struct ifnet *ifp, u_long cmd, void *data)
{
struct ifaddr *ifa = (struct ifaddr *)data;
struct ifreq *ifr = (struct ifreq *)data;
int s = splnet(), error = 0;
struct sl_softc *sc = ifp->if_softc;
struct ppp_stats *psp;
struct ppp_comp_stats *pcp;

switch (cmd) {

case SIOCINITIFADDR:
if (ifa->ifa_addr->sa_family == AF_INET)
ifp->if_flags |= IFF_UP;
else
error = EAFNOSUPPORT;
break;

case SIOCSIFDSTADDR:
if (ifreq_getaddr(cmd, ifr)->sa_family != AF_INET)
error = EAFNOSUPPORT;
break;

case SIOCSIFMTU:
if ((ifr->ifr_mtu < 3) || (ifr->ifr_mtu > SLMAX)) {
error = EINVAL;
break;
}
/*FALLTHROUGH*/
case SIOCGIFMTU:
if ((error = ifioctl_common(&sc->sc_if, cmd, data)) == ENETRESET)
error = 0;
break;

case SIOCADDMULTI:
case SIOCDELMULTI:
if (ifr == 0) {
error = EAFNOSUPPORT; /* XXX */
break;
}
switch (ifreq_getaddr(cmd, ifr)->sa_family) {

#ifdef INET
case AF_INET:
break;
#endif

default:
error = EAFNOSUPPORT;
break;
}
break;

case SIOCGPPPSTATS: {
struct if_data ifi;

if_export_if_data(&sc->sc_if, &ifi, false);
psp = &((struct ifpppstatsreq *) data)->stats;
(void)memset(psp, 0, sizeof(*psp));
psp->p.ppp_ibytes = ifi.ifi_ibytes;
psp->p.ppp_ipackets = ifi.ifi_ipackets;
psp->p.ppp_ierrors = ifi.ifi_ierrors;
psp->p.ppp_obytes = ifi.ifi_obytes;
psp->p.ppp_opackets = ifi.ifi_opackets;
psp->p.ppp_oerrors = ifi.ifi_oerrors;
#ifdef INET
psp->vj.vjs_packets = sc->sc_comp.sls_packets;
psp->vj.vjs_compressed = sc->sc_comp.sls_compressed;
psp->vj.vjs_searches = sc->sc_comp.sls_searches;
psp->vj.vjs_misses = sc->sc_comp.sls_misses;
psp->vj.vjs_uncompressedin = sc->sc_comp.sls_uncompressedin;
psp->vj.vjs_compressedin = sc->sc_comp.sls_compressedin;
psp->vj.vjs_errorin = sc->sc_comp.sls_errorin;
psp->vj.vjs_tossed = sc->sc_comp.sls_tossed;
#endif
}
break;

case SIOCGPPPCSTATS:
pcp = &((struct ifpppcstatsreq *) data)->stats;
(void)memset(pcp, 0, sizeof(*pcp));
break;

default:
error = ifioctl_common(ifp, cmd, data);
break;
}
splx(s);
return error;
}

/*
* Module infrastructure
*/

#include "if_module.h"

IF_MODULE(MODULE_CLASS_DRIVER, sl, "slcompress");