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pcap-enet.c

/*
 * Stanford Enetfilter subroutines for tcpdump
 *
 * Based on the MERIT NNstat etherifrt.c and the Ultrix pcap-pf.c
 * subroutines.
 *
 * Rayan Zachariassen, CA*Net
 */
#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/libpcap/pcap-enet.c,v 1.8 2003/11/15 23:24:02 guy Exp $";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/types.h>
#include <sys/time.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>

#include <net/if.h>
#include <pcap-bpf.h>
#include <net/enet.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>

#include <stdio.h>
#include <errno.h>

#include "interface.h"

struct packet_header {
#ifdef      IBMRTPC
      struct LengthWords      length;
      struct tap_header tap;
#endif      /* IBMRTPC */
      u_char                  packet[8]
};

extern int errno;

#define BUFSPACE (4*1024)

/* Forwards */
static void efReadError(int, char *);

void
readloop(int cnt, int if_fd, struct bpf_program *fp, printfunc printit)
{
#ifdef      IBMRTPC
      register struct packet_header *ph;
      register u_char *bp;
      register int inc;
#else /* !IBMRTPC */
      static struct timeval tv = { 0 };
#endif      /* IBMRTPC */
      register int cc, caplen;
      register struct bpf_insn *fcode = fp->bf_insns;
      union {
            struct packet_header hdr;
            u_char      p[BUFSPACE];
            u_short     s;
      } buf;

      while (1) {
            if ((cc = read(if_fd, (char *)buf.p, sizeof(buf))) < 0)
                  efReadError(if_fd, "reader");

#ifdef      IBMRTPC
            /*
             * Loop through each packet.
             */
            bp = buf.p;
            while (cc > 0) {
                  ph = (struct packet_header *)bp;
                  caplen = ph->tap.th_wirelen > snaplen ? snaplen : ph->tap
.th_wirelen ;
                  if (bpf_filter(fcode, (char *)ph->packet,
                                    ph->tap.th_wirelen, caplen)) {
                        if (cnt >= 0 && --cnt < 0)
                              goto out;
                        (*printit)((char *)ph->packet,
                              (struct timeval *)ph->tap.th_timestamp,
                              ph->tap.th_wirelen, caplen);
                  }
                  inc = ph->length.PacketOffset;
                  cc -= inc;
                  bp += inc;
            }
#else /* !IBMRTPC */
            caplen = cc > snaplen ? snaplen : cc ;
            if (bpf_filter(fcode, buf.hdr.packet, cc, caplen)) {
                  if (cnt >= 0 && --cnt < 0)
                        goto out;
                  (*printit)(buf.hdr.packet, &tv, cc, caplen);
            }
#endif      /* IBMRTPC */
      }
 out:
      wrapup(if_fd);
}

/* Call ONLY if read() has returned an error on packet filter */
static void
efReadError(int fid, char *msg)
{
      if (errno == EINVAL) {  /* read MAXINT bytes already! */
            if (lseek(fid, 0, 0) < 0) {
                  perror("tcpdump: efReadError/lseek");
                  exit(-1);
            }
            else
                  return;
      }
      else {
            (void) fprintf(stderr, "tcpdump: ");
            perror(msg);
            exit(-1);
      }
}

void
wrapup(int fd)
{
#ifdef      IBMRTPC
      struct enstats es;

      if (ioctl(fd, EIOSTATS, &es) == -1) {
            perror("tcpdump: enet ioctl EIOSTATS error");
            exit(-1);
      }

      fprintf(stderr, "%d packets queued", es.enStat_Rcnt);
      if (es.enStat_Rdrops > 0)
            fprintf(stderr, ", %d dropped", es.enStat_Rdrops);
      if (es.enStat_Reads > 0)
            fprintf(stderr, ", %d tcpdump %s", es.enStat_Reads,
                        es.enStat_Reads > 1 ? "reads" : "read");
      if (es.enStat_MaxRead > 1)
            fprintf(stderr, ", %d packets in largest read",
                  es.enStat_MaxRead);
      putc('\n', stderr);
#endif      /* IBMRTPC */
      close(fd);
}

int
initdevice(char *device, int pflag, int *linktype)
{
      struct eniocb ctl;
      struct enfilter filter;
      u_int maxwaiting;
      int if_fd;

#ifdef      IBMRTPC
      GETENETDEVICE(0, O_RDONLY, &if_fd);
#else /* !IBMRTPC */
      if_fd = open("/dev/enet", O_RDONLY, 0);
#endif      /* IBMRTPC */

      if (if_fd == -1) {
            perror("tcpdump: enet open error");
            error(
"your system may not be properly configured; see \"man enet(4)\"");
            exit(-1);
      }

      /*  Get operating parameters. */

      if (ioctl(if_fd, EIOCGETP, (char *)&ctl) == -1) {
            perror("tcpdump: enet ioctl EIOCGETP error");
            exit(-1);
      }

      /*  Set operating parameters. */

#ifdef      IBMRTPC
      ctl.en_rtout = 1 * ctl.en_hz;
      ctl.en_tr_etherhead = 1;
      ctl.en_tap_network = 1;
      ctl.en_multi_packet = 1;
      ctl.en_maxlen = BUFSPACE;
#else /* !IBMRTPC */
      ctl.en_rtout = 64;      /* randomly picked value for HZ */
#endif      /* IBMRTPC */
      if (ioctl(if_fd, EIOCSETP, &ctl) == -1) {
            perror("tcpdump: enet ioctl EIOCSETP error");
            exit(-1);
      }

      /*  Flush the receive queue, since we've changed
          the operating parameters and we otherwise might
          receive data without headers. */

      if (ioctl(if_fd, EIOCFLUSH) == -1) {
            perror("tcpdump: enet ioctl EIOCFLUSH error");
            exit(-1);
      }

      /*  Set the receive queue depth to its maximum. */

      maxwaiting = ctl.en_maxwaiting;
      if (ioctl(if_fd, EIOCSETW, &maxwaiting) == -1) {
            perror("tcpdump: enet ioctl EIOCSETW error");
            exit(-1);
      }

#ifdef      IBMRTPC
      /*  Clear statistics. */

      if (ioctl(if_fd, EIOCLRSTAT, 0) == -1) {
            perror("tcpdump: enet ioctl EIOCLRSTAT error");
            exit(-1);
      }
#endif      /* IBMRTPC */

      /*  Set the filter (accept all packets). */

      filter.enf_Priority = 3;
      filter.enf_FilterLen = 0;
      if (ioctl(if_fd, EIOCSETF, &filter) == -1) {
            perror("tcpdump: enet ioctl EIOCSETF error");
            exit(-1);
      }
      /*
       * "enetfilter" supports only ethernets.
       */
      *linktype = DLT_EN10MB;

      return(if_fd);
}

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