text: /*
   * Stanford Enetfilter subroutines for tcpdump
   *
   * Based on the MERIT NNstat etherifrt.c and the Ultrix pcap-pf.c
   * subroutines.
   *
   * Rayan Zachariassen, CA*Net
   */
  
  #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);
  }
  