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pcap-snit.c

/*
 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996
 *    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: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Modifications made to accommodate the new SunOS4.0 NIT facility by
 * Micky Liu, micky@cunixc.cc.columbia.edu, Columbia University in May, 1989.
 * This module now handles the STREAMS based NIT.
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/libpcap/pcap-snit.c,v 1.72.2.1 2005/05/03 18:54:38 guy Exp $ (LBL)";
#endif

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

#include <sys/types.h>
#include <sys/time.h>
#include <sys/timeb.h>
#include <sys/dir.h>
#include <sys/fcntlcom.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stropts.h>

#include <net/if.h>
#include <net/nit.h>
#include <net/nit_if.h>
#include <net/nit_pf.h>
#include <net/nit_buf.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/if_ether.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/tcp.h>
#include <netinet/tcpip.h>

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "pcap-int.h"

#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif

/*
 * The chunk size for NIT.  This is the amount of buffering
 * done for read calls.
 */
#define CHUNKSIZE (2*1024)

/*
 * The total buffer space used by NIT.
 */
#define BUFSPACE (4*CHUNKSIZE)

/* Forwards */
static int nit_setflags(int, int, int, char *);

static int
pcap_stats_snit(pcap_t *p, struct pcap_stat *ps)
{

      /*
       * "ps_recv" counts packets handed to the filter, not packets
       * that passed the filter.  As filtering is done in userland,
       * this does not include packets dropped because we ran out
       * of buffer space.
       *
       * "ps_drop" counts packets dropped inside the "/dev/nit"
       * device because of flow control requirements or resource
       * exhaustion; it doesn't count packets dropped by the
       * interface driver, or packets dropped upstream.  As filtering
       * is done in userland, it counts packets regardless of whether
       * they would've passed the filter.
       *
       * These statistics don't include packets not yet read from the
       * kernel by libpcap or packets not yet read from libpcap by the
       * application.
       */
      *ps = p->md.stat;
      return (0);
}

static int
pcap_read_snit(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
      register int cc, n;
      register struct bpf_insn *fcode = p->fcode.bf_insns;
      register u_char *bp, *cp, *ep;
      register struct nit_bufhdr *hdrp;
      register struct nit_iftime *ntp;
      register struct nit_iflen *nlp;
      register struct nit_ifdrops *ndp;
      register int caplen;

      cc = p->cc;
      if (cc == 0) {
            cc = read(p->fd, (char *)p->buffer, p->bufsize);
            if (cc < 0) {
                  if (errno == EWOULDBLOCK)
                        return (0);
                  snprintf(p->errbuf, sizeof(p->errbuf), "pcap_read: %s",
                        pcap_strerror(errno));
                  return (-1);
            }
            bp = p->buffer;
      } else
            bp = p->bp;

      /*
       * loop through each snapshot in the chunk
       */
      n = 0;
      ep = bp + cc;
      while (bp < ep) {
            /*
             * Has "pcap_breakloop()" been called?
             * If so, return immediately - if we haven't read any
             * packets, clear the flag and return -2 to indicate
             * that we were told to break out of the loop, otherwise
             * leave the flag set, so that the *next* call will break
             * out of the loop without having read any packets, and
             * return the number of packets we've processed so far.
             */
            if (p->break_loop) {
                  if (n == 0) {
                        p->break_loop = 0;
                        return (-2);
                  } else {
                        p->bp = bp;
                        p->cc = ep - bp;
                        return (n);
                  }
            }

            ++p->md.stat.ps_recv;
            cp = bp;

            /* get past NIT buffer  */
            hdrp = (struct nit_bufhdr *)cp;
            cp += sizeof(*hdrp);

            /* get past NIT timer   */
            ntp = (struct nit_iftime *)cp;
            cp += sizeof(*ntp);

            ndp = (struct nit_ifdrops *)cp;
            p->md.stat.ps_drop = ndp->nh_drops;
            cp += sizeof *ndp;

            /* get past packet len  */
            nlp = (struct nit_iflen *)cp;
            cp += sizeof(*nlp);

            /* next snapshot        */
            bp += hdrp->nhb_totlen;

            caplen = nlp->nh_pktlen;
            if (caplen > p->snapshot)
                  caplen = p->snapshot;

            if (bpf_filter(fcode, cp, nlp->nh_pktlen, caplen)) {
                  struct pcap_pkthdr h;
                  h.ts = ntp->nh_timestamp;
                  h.len = nlp->nh_pktlen;
                  h.caplen = caplen;
                  (*callback)(user, &h, cp);
                  if (++n >= cnt && cnt >= 0) {
                        p->cc = ep - bp;
                        p->bp = bp;
                        return (n);
                  }
            }
      }
      p->cc = 0;
      return (n);
}

static int
pcap_inject_snit(pcap_t *p, const void *buf, size_t size)
{
      struct strbuf ctl, data;
      
      /*
       * XXX - can we just do
       *
      ret = write(pd->f, buf, size);
       */
      ctl.len = sizeof(*sa);  /* XXX - what was this? */
      ctl.buf = (char *)sa;
      data.buf = buf;
      data.len = size;
      ret = putmsg(p->fd, &ctl, &data);
      if (ret == -1) {
            snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
                pcap_strerror(errno));
            return (-1);
      }
      return (ret);
}

static int
nit_setflags(int fd, int promisc, int to_ms, char *ebuf)
{
      bpf_u_int32 flags;
      struct strioctl si;
      struct timeval timeout;

      si.ic_timout = INFTIM;
      if (to_ms != 0) {
            timeout.tv_sec = to_ms / 1000;
            timeout.tv_usec = (to_ms * 1000) % 1000000;
            si.ic_cmd = NIOCSTIME;
            si.ic_len = sizeof(timeout);
            si.ic_dp = (char *)&timeout;
            if (ioctl(fd, I_STR, (char *)&si) < 0) {
                  snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSTIME: %s",
                      pcap_strerror(errno));
                  return (-1);
            }
      }
      flags = NI_TIMESTAMP | NI_LEN | NI_DROPS;
      if (promisc)
            flags |= NI_PROMISC;
      si.ic_cmd = NIOCSFLAGS;
      si.ic_len = sizeof(flags);
      si.ic_dp = (char *)&flags;
      if (ioctl(fd, I_STR, (char *)&si) < 0) {
            snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSFLAGS: %s",
                pcap_strerror(errno));
            return (-1);
      }
      return (0);
}

pcap_t *
pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
    char *ebuf)
{
      struct strioctl si;           /* struct for ioctl() */
      struct ifreq ifr;       /* interface request struct */
      int chunksize = CHUNKSIZE;
      int fd;
      static char dev[] = "/dev/nit";
      register pcap_t *p;

      p = (pcap_t *)malloc(sizeof(*p));
      if (p == NULL) {
            strlcpy(ebuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
            return (NULL);
      }

      if (snaplen < 96)
            /*
             * NIT requires a snapshot length of at least 96.
             */
            snaplen = 96;

      memset(p, 0, sizeof(*p));
      /*
       * Initially try a read/write open (to allow the inject
       * method to work).  If that fails due to permission
       * issues, fall back to read-only.  This allows a
       * non-root user to be granted specific access to pcap
       * capabilities via file permissions.
       *
       * XXX - we should have an API that has a flag that
       * controls whether to open read-only or read-write,
       * so that denial of permission to send (or inability
       * to send, if sending packets isn't supported on
       * the device in question) can be indicated at open
       * time.
       */
      p->fd = fd = open(dev, O_RDWR);
      if (fd < 0 && errno == EACCES)
            p->fd = fd = open(dev, O_RDONLY);
      if (fd < 0) {
            snprintf(ebuf, PCAP_ERRBUF_SIZE, "%s: %s", dev,
                pcap_strerror(errno));
            goto bad;
      }

      /* arrange to get discrete messages from the STREAM and use NIT_BUF */
      if (ioctl(fd, I_SRDOPT, (char *)RMSGD) < 0) {
            snprintf(ebuf, PCAP_ERRBUF_SIZE, "I_SRDOPT: %s",
                pcap_strerror(errno));
            goto bad;
      }
      if (ioctl(fd, I_PUSH, "nbuf") < 0) {
            snprintf(ebuf, PCAP_ERRBUF_SIZE, "push nbuf: %s",
                pcap_strerror(errno));
            goto bad;
      }
      /* set the chunksize */
      si.ic_cmd = NIOCSCHUNK;
      si.ic_timout = INFTIM;
      si.ic_len = sizeof(chunksize);
      si.ic_dp = (char *)&chunksize;
      if (ioctl(fd, I_STR, (char *)&si) < 0) {
            snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSCHUNK: %s",
                pcap_strerror(errno));
            goto bad;
      }

      /* request the interface */
      strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
      ifr.ifr_name[sizeof(ifr.ifr_name) - 1] = '\0';
      si.ic_cmd = NIOCBIND;
      si.ic_len = sizeof(ifr);
      si.ic_dp = (char *)&ifr;
      if (ioctl(fd, I_STR, (char *)&si) < 0) {
            snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCBIND: %s: %s",
                  ifr.ifr_name, pcap_strerror(errno));
            goto bad;
      }

      /* set the snapshot length */
      si.ic_cmd = NIOCSSNAP;
      si.ic_len = sizeof(snaplen);
      si.ic_dp = (char *)&snaplen;
      if (ioctl(fd, I_STR, (char *)&si) < 0) {
            snprintf(ebuf, PCAP_ERRBUF_SIZE, "NIOCSSNAP: %s",
                pcap_strerror(errno));
            goto bad;
      }
      p->snapshot = snaplen;
      if (nit_setflags(p->fd, promisc, to_ms, ebuf) < 0)
            goto bad;

      (void)ioctl(fd, I_FLUSH, (char *)FLUSHR);
      /*
       * NIT supports only ethernets.
       */
      p->linktype = DLT_EN10MB;

      p->bufsize = BUFSPACE;
      p->buffer = (u_char *)malloc(p->bufsize);
      if (p->buffer == NULL) {
            strlcpy(ebuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
            goto bad;
      }

      /*
       * "p->fd" is an FD for a STREAMS device, so "select()" and
       * "poll()" should work on it.
       */
      p->selectable_fd = p->fd;

      /*
       * This is (presumably) a real Ethernet capture; give it a
       * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
       * that an application can let you choose it, in case you're
       * capturing DOCSIS traffic that a Cisco Cable Modem
       * Termination System is putting out onto an Ethernet (it
       * doesn't put an Ethernet header onto the wire, it puts raw
       * DOCSIS frames out on the wire inside the low-level
       * Ethernet framing).
       */
      p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
      /*
       * If that fails, just leave the list empty.
       */
      if (p->dlt_list != NULL) {
            p->dlt_list[0] = DLT_EN10MB;
            p->dlt_list[1] = DLT_DOCSIS;
            p->dlt_count = 2;
      }

      p->read_op = pcap_read_snit;
      p->inject_op = pcap_inject_snit;
      p->setfilter_op = install_bpf_program;    /* no kernel filtering */
      p->setdirection_op = NULL;    /* Not implemented. */
      p->set_datalink_op = NULL;    /* can't change data link type */
      p->getnonblock_op = pcap_getnonblock_fd;
      p->setnonblock_op = pcap_setnonblock_fd;
      p->stats_op = pcap_stats_snit;
      p->close_op = pcap_close_common;

      return (p);
 bad:
      if (fd >= 0)
            close(fd);
      free(p);
      return (NULL);
}

int
pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
{
      return (0);
}

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