/*      $NetBSD: bpf.c,v 1.22 2022/09/03 07:45:08 tsutsui Exp $ */

/*
* Copyright (c) 1988, 1992 The University of Utah and the Center
*      for Software Science (CSS).
* Copyright (c) 1992, 1993
*      The Regents of the University of California.  All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Center for Software Science of the University of Utah Computer
* Science Department.  CSS requests users of this software to return
* to [email protected] any improvements that they make and grant
* CSS redistribution rights.
*
* 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.
*
*      from: @(#)bpf.c 8.1 (Berkeley) 6/4/93
*
* From: Utah Hdr: bpf.c 3.1 92/07/06
* Author: Jeff Forys, University of Utah CSS
*/

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)bpf.c       8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: bpf.c,v 1.22 2022/09/03 07:45:08 tsutsui Exp $");
#endif
#endif /* not lint */

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/socket.h>

#include <net/if.h>
#include <net/bpf.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <paths.h>
#include <unistd.h>
#include <ifaddrs.h>
#include "defs.h"
#include "pathnames.h"

static int BpfFd = -1;
static unsigned BpfLen = 0;
static u_int8_t *BpfPkt = NULL;

/*
**  BpfOpen -- Open and initialize a BPF device.
**
**      Parameters:
**              None.
**
**      Returns:
**              File descriptor of opened BPF device (for select() etc).
**
**      Side Effects:
**              If an error is encountered, the program terminates here.
*/
int
BpfOpen(void)
{
       struct ifreq ifr;
       u_int bufsize = 32768;
       int n;

       BpfFd = open(_PATH_BPF, O_RDWR);
       if (BpfFd < 0) {
               syslog(LOG_ERR, "bpf: no available devices: %m");
               Exit(0);
       }

       if (ioctl(BpfFd, BIOCSBLEN, &bufsize) < 0) {
               syslog(LOG_ERR, "bpf: ioctl(BIOCSBLEN,%d): %m", bufsize);
       }

       /*
        *  Set interface name for bpf device, get data link layer
        *  type and make sure it's type Ethernet.
        */
       (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name));
       if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) {
               syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName);
               Exit(0);
       }

       /*
        *  Make sure we are dealing with an Ethernet device.
        */
       if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) {
               syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m");
               Exit(0);
       }
       if (n != DLT_EN10MB) {
               syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported",
                      IntfName, n);
               Exit(0);
       }

       /*
        *  On read(), return packets immediately (do not buffer them).
        */
       n = 1;
       if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) {
               syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m");
               Exit(0);
       }

       /*
        *  Try to enable the chip/driver's multicast address filter to
        *  grab our RMP address.  If this fails, try promiscuous mode.
        *  If this fails, there's no way we are going to get any RMP
        *  packets so just exit here.
        */
#ifdef MSG_EOR
       ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
#endif
       ifr.ifr_addr.sa_family = AF_UNSPEC;
       memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0],
           RMP_ADDRLEN);
       if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) {
               syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m");
               Exit(0);
       }

       /*
        *  Ask BPF how much buffer space it requires and allocate one.
        */
       if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) {
               syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m");
               Exit(0);
       }
       if (BpfPkt == NULL)
               BpfPkt = (u_int8_t *)malloc(BpfLen);

       if (BpfPkt == NULL) {
               syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)",
                      BpfLen);
               Exit(0);
       }

       /*
        *  Write a little program to snarf RMP Boot packets and stuff
        *  it down BPF's throat (i.e. set up the packet filter).
        */
       {
#define RMP     ((struct rmp_packet *)0)
               static struct bpf_insn bpf_insn[] = {
                   { BPF_LD|BPF_B|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dsap },
                   { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP },
                   { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.cntrl },
                   { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP },
                   { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dxsap },
                   { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP },
                   { BPF_RET|BPF_K,         0, 0, RMP_MAX_PACKET },
                   { BPF_RET|BPF_K,         0, 0, 0x0 }
               };
#undef  RMP
               static struct bpf_program bpf_pgm = {
                   sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn
               };

               if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) {
                       syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m");
                       Exit(0);
               }
       }

       return(BpfFd);
}

/*
**  BPF GetIntfName -- Return the name of a network interface attached to
**              the system, or 0 if none can be found.  The interface
**              must be configured up; the lowest unit number is
**              preferred; loopback is ignored.
**
**      Parameters:
**              errmsg - if no network interface found, *errmsg explains why.
**
**      Returns:
**              A (static) pointer to interface name, or NULL on error.
**
**      Side Effects:
**              None.
*/
char *
BpfGetIntfName(char **errmsg)
{
       struct ifaddrs *ifap, *ifa, *p;
       int minunit, n;
       char *cp;
       static char device[IFNAMSIZ + 1];
       static char errbuf[128] = "No Error!";

       if (errmsg != NULL)
               *errmsg = errbuf;

       if (getifaddrs(&ifap) != 0) {
               (void) strlcpy(errbuf, "bpf: getifaddrs: %m", sizeof(errbuf));
               return(NULL);
       }

       p = NULL;
       minunit = 666;
       for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
               /*
                *  If interface is down or this is the loopback interface,
                *  ignore it.
                */
               if ((ifa->ifa_flags & IFF_UP) == 0 ||
#ifdef IFF_LOOPBACK
                   (ifa->ifa_flags & IFF_LOOPBACK))
#else
                   (strcmp(ifa->ifa_name, "lo0") == 0))
#endif
                       continue;

               for (cp = ifa->ifa_name; !isdigit((unsigned char)*cp); ++cp)
                       ;
               n = atoi(cp);
               if (n < minunit) {
                       minunit = n;
                       p = ifa;
               }
       }
       if (p == NULL) {
               (void) strlcpy(errbuf, "bpf: no interfaces found",
                   sizeof(errbuf));
               freeifaddrs(ifap);
               return(NULL);
       }

       (void) strlcpy(device, p->ifa_name, sizeof(device));
       freeifaddrs(ifap);
       return(device);
}

/*
**  BpfRead -- Read packets from a BPF device and fill in `rconn'.
**
**      Parameters:
**              rconn - filled in with next packet.
**              doread - is True if we can issue a read() syscall.
**
**      Returns:
**              True if `rconn' contains a new packet, False otherwise.
**
**      Side Effects:
**              None.
*/
int
BpfRead(RMPCONN *rconn, int doread)
{
       int datlen, caplen, hdrlen;
       static u_int8_t *bp = NULL, *ep = NULL;
       int cc;

       /*
        *  The read() may block, or it may return one or more packets.
        *  We let the caller decide whether or not we can issue a read().
        */
       if (doread) {
               if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) {
                       syslog(LOG_ERR, "bpf: read: %m");
                       return(0);
               } else {
                       bp = BpfPkt;
                       ep = BpfPkt + cc;
               }
       }

#define bhp ((struct bpf_hdr *)bp)
       /*
        *  If there is a new packet in the buffer, stuff it into `rconn'
        *  and return a success indication.
        */
       if (bp < ep) {
               datlen = bhp->bh_datalen;
               caplen = bhp->bh_caplen;
               hdrlen = bhp->bh_hdrlen;

               if (caplen != datlen)
                       syslog(LOG_ERR,
                              "bpf: short packet dropped (%d of %d bytes)",
                              caplen, datlen);
               else if (caplen > (int)sizeof(struct rmp_packet))
                       syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)",
                              caplen);
               else {
                       rconn->rmplen = caplen;
                       memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp,
                         sizeof(struct timeval));
                       memmove((char *)&rconn->rmp, (char *)bp + hdrlen,
                           caplen);
               }
               bp += BPF_WORDALIGN(caplen + hdrlen);
               return(1);
       }
#undef bhp

       return(0);
}

/*
**  BpfWrite -- Write packet to BPF device.
**
**      Parameters:
**              rconn - packet to send.
**
**      Returns:
**              True if write succeeded, False otherwise.
**
**      Side Effects:
**              None.
*/
int
BpfWrite(RMPCONN *rconn)
{
       if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) {
               syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn));
               return(0);
       }

       return(1);
}

/*
**  BpfClose -- Close a BPF device.
**
**      Parameters:
**              None.
**
**      Returns:
**              Nothing.
**
**      Side Effects:
**              None.
*/
void
BpfClose(void)
{
       struct ifreq ifr;

       if (BpfPkt != NULL) {
               free((char *)BpfPkt);
               BpfPkt = NULL;
       }

       if (BpfFd == -1)
               return;

#ifdef MSG_EOR
       ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
#endif
       ifr.ifr_addr.sa_family = AF_UNSPEC;
       memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0],
           RMP_ADDRLEN);
       if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0)
               (void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0);

       (void) close(BpfFd);
       BpfFd = -1;
}

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