/src/libpcap-1.9.1/pcap-usb-linux.c

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/*
 * Copyright (c) 2006 Paolo Abeni (Italy)
 * 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. The name of the author may not be used to endorse or promote
 * products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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.
 *
 * USB sniffing API implementation for Linux platform
 * By Paolo Abeni <paolo.abeni@email.it>
 * Modifications: Kris Katterjohn <katterjohn@gmail.com>
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "pcap-int.h"
#include "pcap-usb-linux.h"
#include "pcap/usb.h"

#ifdef NEED_STRERROR_H
#include "strerror.h"
#endif

#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <limits.h>
#include <string.h>
#include <dirent.h>
#include <byteswap.h>
#include <netinet/in.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#ifdef HAVE_LINUX_USBDEVICE_FS_H
/*
 * We might need <linux/compiler.h> to define __user for
 * <linux/usbdevice_fs.h>.
 */
#ifdef HAVE_LINUX_COMPILER_H
#include <linux/compiler.h>
#endif /* HAVE_LINUX_COMPILER_H */
#include <linux/usbdevice_fs.h>
#endif /* HAVE_LINUX_USBDEVICE_FS_H */

#define USB_IFACE "usbmon"
#define USB_TEXT_DIR_OLD "/sys/kernel/debug/usbmon"
#define USB_TEXT_DIR "/sys/kernel/debug/usb/usbmon"
#define SYS_USB_BUS_DIR "/sys/bus/usb/devices"
#define PROC_USB_BUS_DIR "/proc/bus/usb"
#define USB_LINE_LEN 4096

#if __BYTE_ORDER == __LITTLE_ENDIAN
#define htols(s) s
#define htoll(l) l
#define htol64(ll) ll
#else
#define htols(s) bswap_16(s)
#define htoll(l) bswap_32(l)
#define htol64(ll) bswap_64(ll)
#endif

struct mon_bin_stats {
  uint32_t queued;
  uint32_t dropped;
};

struct mon_bin_get {
  pcap_usb_header *hdr;
  void *data;
  size_t data_len;   /* Length of data (can be zero) */
};

struct mon_bin_mfetch {
  int32_t *offvec;   /* Vector of events fetched */
  int32_t nfetch;    /* Number of events to fetch (out: fetched) */
  int32_t nflush;    /* Number of events to flush */
};

#define MON_IOC_MAGIC 0x92

#define MON_IOCQ_URB_LEN _IO(MON_IOC_MAGIC, 1)
#define MON_IOCX_URB  _IOWR(MON_IOC_MAGIC, 2, struct mon_bin_hdr)
#define MON_IOCG_STATS _IOR(MON_IOC_MAGIC, 3, struct mon_bin_stats)
#define MON_IOCT_RING_SIZE _IO(MON_IOC_MAGIC, 4)
#define MON_IOCQ_RING_SIZE _IO(MON_IOC_MAGIC, 5)
#define MON_IOCX_GET   _IOW(MON_IOC_MAGIC, 6, struct mon_bin_get)
#define MON_IOCX_MFETCH _IOWR(MON_IOC_MAGIC, 7, struct mon_bin_mfetch)
#define MON_IOCH_MFLUSH _IO(MON_IOC_MAGIC, 8)

#define MON_BIN_SETUP   0x1 /* setup hdr is present*/
#define MON_BIN_SETUP_ZERO  0x2 /* setup buffer is not available */
#define MON_BIN_DATA_ZERO   0x4 /* data buffer is not available */
#define MON_BIN_ERROR   0x8

/*
 * Private data for capturing on Linux USB.
 */
struct pcap_usb_linux {
  u_char *mmapbuf;  /* memory-mapped region pointer */
  size_t mmapbuflen;  /* size of region */
  int bus_index;
  u_int packets_read;
};

/* forward declaration */
static int usb_activate(pcap_t *);
static int usb_stats_linux(pcap_t *, struct pcap_stat *);
static int usb_stats_linux_bin(pcap_t *, struct pcap_stat *);
static int usb_read_linux(pcap_t *, int , pcap_handler , u_char *);
static int usb_read_linux_bin(pcap_t *, int , pcap_handler , u_char *);
static int usb_read_linux_mmap(pcap_t *, int , pcap_handler , u_char *);
static int usb_inject_linux(pcap_t *, const void *, size_t);
static int usb_setdirection_linux(pcap_t *, pcap_direction_t);
static void usb_cleanup_linux_mmap(pcap_t *);

static int
have_binary_usbmon(void)
{
  struct utsname utsname;
  char *version_component, *endp;
  int major, minor, subminor;

  if (uname(&utsname) == 0) {
    /*
     * 2.6.21 is the first release with the binary-mode
     * USB monitoring.
     */
    version_component = utsname.release;
    major = strtol(version_component, &endp, 10);
    if (endp != version_component && *endp == '.') {
      /*
       * OK, that was a valid major version.
       * Is it 3 or greater?  If so, we have binary
       * mode support.
       */
      if (major >= 3)
        return 1;

      /*
       * Is it 1 or less?  If so, we don't have binary
       * mode support.  (In fact, we don't have any
       * USB monitoring....)
       */
      if (major <= 1)
        return 0;
    }

    /*
     * OK, this is a 2.x kernel.
     * What's the minor version?
     */
    version_component = endp + 1;
    minor = strtol(version_component, &endp, 10);
    if (endp != version_component &&
        (*endp == '.' || *endp == '\0')) {
      /*
       * OK, that was a valid minor version.
       * Is is 2.6 or later?  (There shouldn't be a
       * "later", as 2.6.x went to 3.x, but we'll
       * check anyway.)
       */
      if (minor < 6) {
        /*
         * No, so no binary support (did 2.4 have
         * any USB monitoring at all?)
         */
        return 0;
      }

      /*
       * OK, this is a 2.6.x kernel.
       * What's the subminor version?
       */
      version_component = endp + 1;
      subminor = strtol(version_component, &endp, 10);
      if (endp != version_component &&
          (*endp == '.' || *endp == '\0')) {
        /*
         * OK, that was a valid subminor version.
         * Is it 21 or greater?
         */
        if (subminor >= 21) {
          /*
           * Yes - we have binary mode
           * support.
           */
          return 1;
        }
      }
    }
  }

  /*
   * Either uname() failed, in which case we just say "no binary
   * mode support", or we don't have binary mode support.
   */
  return 0;
}

/* facility to add an USB device to the device list*/
static int
usb_dev_add(pcap_if_list_t *devlistp, int n, char *err_str)
{
  char dev_name[10];
  char dev_descr[30];
  pcap_snprintf(dev_name, 10, USB_IFACE"%d", n);
  /*
   * XXX - is there any notion of "up" and "running"?
   */
  if (n == 0) {
    /*
     * As this refers to all buses, there's no notion of
     * "connected" vs. "disconnected", as that's a property
     * that would apply to a particular USB interface.
     */
    if (add_dev(devlistp, dev_name,
        PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
        "Raw USB traffic, all USB buses", err_str) == NULL)
      return -1;
  } else {
    /*
     * XXX - is there a way to determine whether anything's
     * plugged into this bus interface or not, and set
     * PCAP_IF_CONNECTION_STATUS_CONNECTED or
     * PCAP_IF_CONNECTION_STATUS_DISCONNECTED?
     */
    pcap_snprintf(dev_descr, 30, "Raw USB traffic, bus number %d", n);
    if (add_dev(devlistp, dev_name, 0, dev_descr, err_str) == NULL)
      return -1;
  }

  return 0;
}

int
usb_findalldevs(pcap_if_list_t *devlistp, char *err_str)
{
  char usb_mon_dir[PATH_MAX];
  char *usb_mon_prefix;
  size_t usb_mon_prefix_len;
  struct dirent* data;
  int ret = 0;
  DIR* dir;
  int n;
  char* name;
  size_t len;

  if (have_binary_usbmon()) {
    /*
     * We have binary-mode support.
     * What do the device names look like?
     * Split LINUX_USB_MON_DEV into a directory that we'll
     * scan and a file name prefix that we'll check for.
     */
    pcap_strlcpy(usb_mon_dir, LINUX_USB_MON_DEV, sizeof usb_mon_dir);
    usb_mon_prefix = strrchr(usb_mon_dir, '/');
    if (usb_mon_prefix == NULL) {
      /*
       * This "shouldn't happen".  Just give up if it
       * does.
       */
      return 0;
    }
    *usb_mon_prefix++ = '\0';
    usb_mon_prefix_len = strlen(usb_mon_prefix);

    /*
     * Open the directory and scan it.
     */
    dir = opendir(usb_mon_dir);
    if (dir != NULL) {
      while ((ret == 0) && ((data = readdir(dir)) != 0)) {
        name = data->d_name;

        /*
         * Is this a usbmon device?
         */
        if (strncmp(name, usb_mon_prefix, usb_mon_prefix_len) != 0)
          continue; /* no */

        /*
         * What's the device number?
         */
        if (sscanf(&name[usb_mon_prefix_len], "%d", &n) == 0)
          continue; /* failed */

        ret = usb_dev_add(devlistp, n, err_str);
      }

      closedir(dir);
    }
    return 0;
  } else {
    /*
     * We have only text mode support.
     * We don't look for the text devices because we can't
     * look for them without root privileges, and we don't
     * want to require root privileges to enumerate devices
     * (we want to let the user to try a device and get
     * an error, rather than seeing no devices and asking
     * "why am I not seeing devices" and forcing a long
     * process of poking to figure out whether it's "no
     * privileges" or "your kernel is too old" or "the
     * usbmon module isn't loaded" or...).
     *
     * Instead, we look to see what buses we have.
     * If the kernel is so old that it doesn't have
     * binary-mode support, it's also so old that
     * it doesn't have a "scan all buses" device.
     *
     * First, try scanning sysfs USB bus directory.
     */
    dir = opendir(SYS_USB_BUS_DIR);
    if (dir != NULL) {
      while ((ret == 0) && ((data = readdir(dir)) != 0)) {
        name = data->d_name;

        if (strncmp(name, "usb", 3) != 0)
          continue;

        if (sscanf(&name[3], "%d", &n) == 0)
          continue;

        ret = usb_dev_add(devlistp, n, err_str);
      }

      closedir(dir);
      return 0;
    }

    /* That didn't work; try scanning procfs USB bus directory. */
    dir = opendir(PROC_USB_BUS_DIR);
    if (dir != NULL) {
      while ((ret == 0) && ((data = readdir(dir)) != 0)) {
        name = data->d_name;
        len = strlen(name);

        /* if this file name does not end with a number it's not of our interest */
        if ((len < 1) || !isdigit(name[--len]))
          continue;
        while (isdigit(name[--len]));
        if (sscanf(&name[len+1], "%d", &n) != 1)
          continue;

        ret = usb_dev_add(devlistp, n, err_str);
      }

      closedir(dir);
      return ret;
    }

    /* neither of them worked */
    return 0;
  }
}

/*
 * Matches what's in mon_bin.c in the Linux kernel.
 */
#define MIN_RING_SIZE (8*1024)
#define MAX_RING_SIZE (1200*1024)

static int
usb_set_ring_size(pcap_t* handle, int header_size)
{
  /*
   * A packet from binary usbmon has:
   *
   *  1) a fixed-length header, of size header_size;
   *  2) descriptors, for isochronous transfers;
   *  3) the payload.
   *
   * The kernel buffer has a size, defaulting to 300KB, with a
   * minimum of 8KB and a maximum of 1200KB.  The size is set with
   * the MON_IOCT_RING_SIZE ioctl; the size passed in is rounded up
   * to a page size.
   *
   * No more than {buffer size}/5 bytes worth of payload is saved.
   * Therefore, if we subtract the fixed-length size from the
   * snapshot length, we have the biggest payload we want (we
   * don't worry about the descriptors - if we have descriptors,
   * we'll just discard the last bit of the payload to get it
   * to fit).  We multiply that result by 5 and set the buffer
   * size to that value.
   */
  int ring_size;

  if (handle->snapshot < header_size)
    handle->snapshot = header_size;
  /* The maximum snapshot size is small enough that this won't overflow */
  ring_size = (handle->snapshot - header_size) * 5;

  /*
   * Will this get an error?
   * (There's no wqy to query the minimum or maximum, so we just
   * copy the value from the kernel source.  We don't round it
   * up to a multiple of the page size.)
   */
  if (ring_size > MAX_RING_SIZE) {
    /*
     * Yes.  Lower the ring size to the maximum, and set the
     * snapshot length to the value that would give us a
     * maximum-size ring.
     */
    ring_size = MAX_RING_SIZE;
    handle->snapshot = header_size + (MAX_RING_SIZE/5);
  } else if (ring_size < MIN_RING_SIZE) {
    /*
     * Yes.  Raise the ring size to the minimum, but leave
     * the snapshot length unchanged, so we show the
     * callback no more data than specified by the
     * snapshot length.
     */
    ring_size = MIN_RING_SIZE;
  }

  if (ioctl(handle->fd, MON_IOCT_RING_SIZE, ring_size) == -1) {
    pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
        errno, "Can't set ring size from fd %d", handle->fd);
    return -1;
  }
  return ring_size;
}

static
int usb_mmap(pcap_t* handle)
{
  struct pcap_usb_linux *handlep = handle->priv;
  int len;

  /*
   * Attempt to set the ring size as appropriate for the snapshot
   * length, reducing the snapshot length if that'd make the ring
   * bigger than the kernel supports.
   */
  len = usb_set_ring_size(handle, (int)sizeof(pcap_usb_header_mmapped));
  if (len == -1) {
    /* Failed.  Fall back on non-memory-mapped access. */
    return 0;
  }

  handlep->mmapbuflen = len;
  handlep->mmapbuf = mmap(0, handlep->mmapbuflen, PROT_READ,
      MAP_SHARED, handle->fd, 0);
  if (handlep->mmapbuf == MAP_FAILED) {
    /*
     * Failed.  We don't treat that as a fatal error, we
     * just try to fall back on non-memory-mapped access.
     */
    return 0;
  }
  return 1;
}

#ifdef HAVE_LINUX_USBDEVICE_FS_H

#define CTRL_TIMEOUT    (5*1000)        /* milliseconds */

#define USB_DIR_IN    0x80
#define USB_TYPE_STANDARD 0x00
#define USB_RECIP_DEVICE  0x00

#define USB_REQ_GET_DESCRIPTOR  6

#define USB_DT_DEVICE   1

/* probe the descriptors of the devices attached to the bus */
/* the descriptors will end up in the captured packet stream */
/* and be decoded by external apps like wireshark */
/* without these identifying probes packet data can't be fully decoded */
static void
probe_devices(int bus)
{
  struct usbdevfs_ctrltransfer ctrl;
  struct dirent* data;
  int ret = 0;
  char buf[sizeof("/dev/bus/usb/000/") + NAME_MAX];
  DIR* dir;

  /* scan usb bus directories for device nodes */
  pcap_snprintf(buf, sizeof(buf), "/dev/bus/usb/%03d", bus);
  dir = opendir(buf);
  if (!dir)
    return;

  while ((ret >= 0) && ((data = readdir(dir)) != 0)) {
    int fd;
    char* name = data->d_name;

    if (name[0] == '.')
      continue;

    pcap_snprintf(buf, sizeof(buf), "/dev/bus/usb/%03d/%s", bus, data->d_name);

    fd = open(buf, O_RDWR);
    if (fd == -1)
      continue;

    /*
     * Sigh.  Different kernels have different member names
     * for this structure.
     */
#ifdef HAVE_STRUCT_USBDEVFS_CTRLTRANSFER_BREQUESTTYPE
    ctrl.bRequestType = USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE;
    ctrl.bRequest = USB_REQ_GET_DESCRIPTOR;
    ctrl.wValue = USB_DT_DEVICE << 8;
    ctrl.wIndex = 0;
    ctrl.wLength = sizeof(buf);
#else
    ctrl.requesttype = USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE;
    ctrl.request = USB_REQ_GET_DESCRIPTOR;
    ctrl.value = USB_DT_DEVICE << 8;
    ctrl.index = 0;
    ctrl.length = sizeof(buf);
#endif
    ctrl.data = buf;
    ctrl.timeout = CTRL_TIMEOUT;

    ret = ioctl(fd, USBDEVFS_CONTROL, &ctrl);

    close(fd);
  }
  closedir(dir);
}
#endif /* HAVE_LINUX_USBDEVICE_FS_H */

pcap_t *
usb_create(const char *device, char *ebuf, int *is_ours)
{
  const char *cp;
  char *cpend;
  long devnum;
  pcap_t *p;

  /* Does this look like a USB monitoring device? */
  cp = strrchr(device, '/');
  if (cp == NULL)
    cp = device;
  /* Does it begin with USB_IFACE? */
  if (strncmp(cp, USB_IFACE, sizeof USB_IFACE - 1) != 0) {
    /* Nope, doesn't begin with USB_IFACE */
    *is_ours = 0;
    return NULL;
  }
  /* Yes - is USB_IFACE followed by a number? */
  cp += sizeof USB_IFACE - 1;
  devnum = strtol(cp, &cpend, 10);
  if (cpend == cp || *cpend != '\0') {
    /* Not followed by a number. */
    *is_ours = 0;
    return NULL;
  }
  if (devnum < 0) {
    /* Followed by a non-valid number. */
    *is_ours = 0;
    return NULL;
  }

  /* OK, it's probably ours. */
  *is_ours = 1;

  p = pcap_create_common(ebuf, sizeof (struct pcap_usb_linux));
  if (p == NULL)
    return (NULL);

  p->activate_op = usb_activate;
  return (p);
}

static int
usb_activate(pcap_t* handle)
{
  struct pcap_usb_linux *handlep = handle->priv;
  char    full_path[USB_LINE_LEN];
  int   ret;

  /*
   * Turn a negative snapshot value (invalid), a snapshot value of
   * 0 (unspecified), or a value bigger than the normal maximum
   * value, into the maximum allowed value.
   *
   * If some application really *needs* a bigger snapshot
   * length, we should just increase MAXIMUM_SNAPLEN.
   */
  if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
    handle->snapshot = MAXIMUM_SNAPLEN;

  /* Initialize some components of the pcap structure. */
  handle->bufsize = handle->snapshot;
  handle->offset = 0;
  handle->linktype = DLT_USB_LINUX;

  handle->inject_op = usb_inject_linux;
  handle->setfilter_op = install_bpf_program; /* no kernel filtering */
  handle->setdirection_op = usb_setdirection_linux;
  handle->set_datalink_op = NULL; /* can't change data link type */
  handle->getnonblock_op = pcap_getnonblock_fd;
  handle->setnonblock_op = pcap_setnonblock_fd;

  /*get usb bus index from device name */
  if (sscanf(handle->opt.device, USB_IFACE"%d", &handlep->bus_index) != 1)
  {
    pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
      "Can't get USB bus index from %s", handle->opt.device);
    return PCAP_ERROR;
  }

  if (have_binary_usbmon())
  {
    /*
     * We have binary-mode support.
     * Try to open the binary interface.
     */
    pcap_snprintf(full_path, USB_LINE_LEN, LINUX_USB_MON_DEV"%d", handlep->bus_index);
    handle->fd = open(full_path, O_RDONLY, 0);
    if (handle->fd < 0)
    {
      /*
       * The attempt failed; why?
       */
      switch (errno) {

      case ENOENT:
        /*
         * The device doesn't exist.
         * That could either mean that there's
         * no support for monitoring USB buses
         * (which probably means "the usbmon
         * module isn't loaded") or that there
         * is but that *particular* device
         * doesn't exist (no "scan all buses"
         * device if the bus index is 0, no
         * such bus if the bus index isn't 0).
         */
        return PCAP_ERROR_NO_SUCH_DEVICE;

      case EACCES:
        /*
         * We didn't have permission to open it.
         */
        return PCAP_ERROR_PERM_DENIED;

      default:
        /*
         * Something went wrong.
         */
        pcap_fmt_errmsg_for_errno(handle->errbuf,
            PCAP_ERRBUF_SIZE, errno,
            "Can't open USB bus file %s", full_path);
        return PCAP_ERROR;
      }
    }

    if (handle->opt.rfmon)
    {
      /*
       * Monitor mode doesn't apply to USB devices.
       */
      close(handle->fd);
      return PCAP_ERROR_RFMON_NOTSUP;
    }

    /* try to use fast mmap access */
    if (usb_mmap(handle))
    {
      /* We succeeded. */
      handle->linktype = DLT_USB_LINUX_MMAPPED;
      handle->stats_op = usb_stats_linux_bin;
      handle->read_op = usb_read_linux_mmap;
      handle->cleanup_op = usb_cleanup_linux_mmap;
#ifdef HAVE_LINUX_USBDEVICE_FS_H
      probe_devices(handlep->bus_index);
#endif

      /*
       * "handle->fd" is a real file, so
       * "select()" and "poll()" work on it.
       */
      handle->selectable_fd = handle->fd;
      return 0;
    }

    /*
     * We failed; try plain binary interface access.
     *
     * Attempt to set the ring size as appropriate for
     * the snapshot length, reducing the snapshot length
     * if that'd make the ring bigger than the kernel
     * supports.
     */
    if (usb_set_ring_size(handle, (int)sizeof(pcap_usb_header)) == -1) {
      /* Failed. */
      close(handle->fd);
      return PCAP_ERROR;
    }
    handle->stats_op = usb_stats_linux_bin;
    handle->read_op = usb_read_linux_bin;
#ifdef HAVE_LINUX_USBDEVICE_FS_H
    probe_devices(handlep->bus_index);
#endif
  }
  else {
    /*
     * We don't have binary mode support.
     * Try opening the text-mode device.
     */
    pcap_snprintf(full_path, USB_LINE_LEN, USB_TEXT_DIR"/%dt", handlep->bus_index);
    handle->fd = open(full_path, O_RDONLY, 0);
    if (handle->fd < 0)
    {
      if (errno == ENOENT)
      {
        /*
         * Not found at the new location; try
         * the old location.
         */
        pcap_snprintf(full_path, USB_LINE_LEN, USB_TEXT_DIR_OLD"/%dt", handlep->bus_index);
        handle->fd = open(full_path, O_RDONLY, 0);
      }
      if (handle->fd < 0) {
        if (errno == ENOENT)
        {
          /*
           * The problem is that the file
           * doesn't exist.  Report that as
           * "no such device".  (That could
           * mean "no such USB bus" or
           * "monitoring not supported".)
           */
          ret = PCAP_ERROR_NO_SUCH_DEVICE;
        }
        else if (errno == EACCES)
        {
          /*
           * The problem is that we don't
           * have sufficient permission to
           * open the file.  Report that.
           */
          ret = PCAP_ERROR_PERM_DENIED;
        }
        else
        {
          /*
           * Some other error.
           */
          ret = PCAP_ERROR;
        }
        pcap_fmt_errmsg_for_errno(handle->errbuf,
            PCAP_ERRBUF_SIZE, errno,
            "Can't open USB bus file %s",
            full_path);
        return ret;
      }
    }

    if (handle->opt.rfmon)
    {
      /*
       * Monitor mode doesn't apply to USB devices.
       */
      close(handle->fd);
      return PCAP_ERROR_RFMON_NOTSUP;
    }

    handle->stats_op = usb_stats_linux;
    handle->read_op = usb_read_linux;
  }

  /*
   * "handle->fd" is a real file, so "select()" and "poll()"
   * work on it.
   */
  handle->selectable_fd = handle->fd;

  /* for plain binary access and text access we need to allocate the read
   * buffer */
  handle->buffer = malloc(handle->bufsize);
  if (!handle->buffer) {
    pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
        errno, "malloc");
    close(handle->fd);
    return PCAP_ERROR;
  }
  return 0;
}

static inline int
ascii_to_int(char c)
{
  return c < 'A' ? c- '0': ((c<'a') ? c - 'A' + 10: c-'a'+10);
}

/*
 * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
 * <linux-kernel-source>/drivers/usb/mon/mon_text.c for urb string
 * format description
 */
static int
usb_read_linux(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
{
  /* see:
  * /usr/src/linux/Documentation/usb/usbmon.txt
  * for message format
  */
  struct pcap_usb_linux *handlep = handle->priv;
  unsigned timestamp;
  int tag, cnt, ep_num, dev_addr, dummy, ret, urb_len, data_len;
  char etype, pipeid1, pipeid2, status[16], urb_tag, line[USB_LINE_LEN];
  char *string = line;
  u_char * rawdata = handle->buffer;
  struct pcap_pkthdr pkth;
  pcap_usb_header* uhdr = (pcap_usb_header*)handle->buffer;
  u_char urb_transfer=0;
  int incoming=0;

  /* ignore interrupt system call errors */
  do {
    ret = read(handle->fd, line, USB_LINE_LEN - 1);
    if (handle->break_loop)
    {
      handle->break_loop = 0;
      return -2;
    }
  } while ((ret == -1) && (errno == EINTR));
  if (ret < 0)
  {
    if (errno == EAGAIN)
      return 0; /* no data there */

    pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
        errno, "Can't read from fd %d", handle->fd);
    return -1;
  }

  /* read urb header; %n argument may increment return value, but it's
  * not mandatory, so does not count on it*/
  string[ret] = 0;
  ret = sscanf(string, "%x %d %c %c%c:%d:%d %s%n", &tag, &timestamp, &etype,
    &pipeid1, &pipeid2, &dev_addr, &ep_num, status,
    &cnt);
  if (ret < 8)
  {
    pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
        "Can't parse USB bus message '%s', too few tokens (expected 8 got %d)",
        string, ret);
    return -1;
  }
  uhdr->id = tag;
  uhdr->device_address = dev_addr;
  uhdr->bus_id = handlep->bus_index;
  uhdr->status = 0;
  string += cnt;

  /* don't use usbmon provided timestamp, since it have low precision*/
  if (gettimeofday(&pkth.ts, NULL) < 0)
  {
    pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
        errno, "Can't get timestamp for message '%s'", string);
    return -1;
  }
  uhdr->ts_sec = pkth.ts.tv_sec;
  uhdr->ts_usec = pkth.ts.tv_usec;

  /* parse endpoint information */
  if (pipeid1 == 'C')
    urb_transfer = URB_CONTROL;
  else if (pipeid1 == 'Z')
    urb_transfer = URB_ISOCHRONOUS;
  else if (pipeid1 == 'I')
    urb_transfer = URB_INTERRUPT;
  else if (pipeid1 == 'B')
    urb_transfer = URB_BULK;
  if (pipeid2 == 'i') {
    ep_num |= URB_TRANSFER_IN;
    incoming = 1;
  }
  if (etype == 'C')
    incoming = !incoming;

  /* direction check*/
  if (incoming)
  {
    if (handle->direction == PCAP_D_OUT)
      return 0;
  }
  else
    if (handle->direction == PCAP_D_IN)
      return 0;
  uhdr->event_type = etype;
  uhdr->transfer_type = urb_transfer;
  uhdr->endpoint_number = ep_num;
  pkth.caplen = sizeof(pcap_usb_header);
  rawdata += sizeof(pcap_usb_header);

  /* check if this is a setup packet */
  ret = sscanf(status, "%d", &dummy);
  if (ret != 1)
  {
    /* this a setup packet, setup data can be filled with underscore if
    * usbmon has not been able to read them, so we must parse this fields as
    * strings */
    pcap_usb_setup* shdr;
    char str1[3], str2[3], str3[5], str4[5], str5[5];
    ret = sscanf(string, "%s %s %s %s %s%n", str1, str2, str3, str4,
    str5, &cnt);
    if (ret < 5)
    {
      pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
        "Can't parse USB bus message '%s', too few tokens (expected 5 got %d)",
        string, ret);
      return -1;
    }
    string += cnt;

    /* try to convert to corresponding integer */
    shdr = &uhdr->setup;
    shdr->bmRequestType = strtoul(str1, 0, 16);
    shdr->bRequest = strtoul(str2, 0, 16);
    shdr->wValue = htols(strtoul(str3, 0, 16));
    shdr->wIndex = htols(strtoul(str4, 0, 16));
    shdr->wLength = htols(strtoul(str5, 0, 16));

    uhdr->setup_flag = 0;
  }
  else
    uhdr->setup_flag = 1;

  /* read urb data */
  ret = sscanf(string, " %d%n", &urb_len, &cnt);
  if (ret < 1)
  {
    pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
      "Can't parse urb length from '%s'", string);
    return -1;
  }
  string += cnt;

  /* urb tag is not present if urb length is 0, so we can stop here
   * text parsing */
  pkth.len = urb_len+pkth.caplen;
  uhdr->urb_len = urb_len;
  uhdr->data_flag = 1;
  data_len = 0;
  if (uhdr->urb_len == 0)
    goto got;

  /* check for data presence; data is present if and only if urb tag is '=' */
  if (sscanf(string, " %c", &urb_tag) != 1)
  {
    pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
      "Can't parse urb tag from '%s'", string);
    return -1;
  }

  if (urb_tag != '=')
    goto got;

  /* skip urb tag and following space */
  string += 3;

  /* if we reach this point we got some urb data*/
  uhdr->data_flag = 0;

  /* read all urb data; if urb length is greater then the usbmon internal
   * buffer length used by the kernel to spool the URB, we get only
   * a partial information.
   * At least until linux 2.6.17 there is no way to set usbmon intenal buffer
   * length and default value is 130. */
  while ((string[0] != 0) && (string[1] != 0) && (pkth.caplen < (bpf_u_int32)handle->snapshot))
  {
    rawdata[0] = ascii_to_int(string[0]) * 16 + ascii_to_int(string[1]);
    rawdata++;
    string+=2;
    if (string[0] == ' ')
      string++;
    pkth.caplen++;
    data_len++;
  }

got:
  uhdr->data_len = data_len;
  if (pkth.caplen > (bpf_u_int32)handle->snapshot)
    pkth.caplen = (bpf_u_int32)handle->snapshot;

  if (handle->fcode.bf_insns == NULL ||
      bpf_filter(handle->fcode.bf_insns, handle->buffer,
        pkth.len, pkth.caplen)) {
    handlep->packets_read++;
    callback(user, &pkth, handle->buffer);
    return 1;
  }
  return 0; /* didn't pass filter */
}

static int
usb_inject_linux(pcap_t *handle, const void *buf _U_, size_t size _U_)
{
  pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
      "Packet injection is not supported on USB devices");
  return (-1);
}

static int
usb_stats_linux(pcap_t *handle, struct pcap_stat *stats)
{
  struct pcap_usb_linux *handlep = handle->priv;
  int dummy, ret, consumed, cnt;
  char string[USB_LINE_LEN];
  char token[USB_LINE_LEN];
  char * ptr = string;
  int fd;

  pcap_snprintf(string, USB_LINE_LEN, USB_TEXT_DIR"/%ds", handlep->bus_index);
  fd = open(string, O_RDONLY, 0);
  if (fd < 0)
  {
    if (errno == ENOENT)
    {
      /*
       * Not found at the new location; try the old
       * location.
       */
      pcap_snprintf(string, USB_LINE_LEN, USB_TEXT_DIR_OLD"/%ds", handlep->bus_index);
      fd = open(string, O_RDONLY, 0);
    }
    if (fd < 0) {
      pcap_fmt_errmsg_for_errno(handle->errbuf,
          PCAP_ERRBUF_SIZE, errno,
          "Can't open USB stats file %s", string);
      return -1;
    }
  }

  /* read stats line */
  do {
    ret = read(fd, string, USB_LINE_LEN-1);
  } while ((ret == -1) && (errno == EINTR));
  close(fd);

  if (ret < 0)
  {
    pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
      "Can't read stats from fd %d ", fd);
    return -1;
  }
  string[ret] = 0;

  stats->ps_recv = handlep->packets_read;
  stats->ps_drop = 0; /* unless we find text_lost */
  stats->ps_ifdrop = 0;

  /* extract info on dropped urbs */
  for (consumed=0; consumed < ret; ) {
    /* from the sscanf man page:
     * The C standard says: "Execution of a %n directive does
     * not increment the assignment count returned at the completion
     * of  execution" but the Corrigendum seems to contradict this.
     * Do not make any assumptions on the effect of %n conversions
     * on the return value and explicitly check for cnt assignmet*/
    int ntok;

    cnt = -1;
    ntok = sscanf(ptr, "%s%n", token, &cnt);
    if ((ntok < 1) || (cnt < 0))
      break;
    consumed += cnt;
    ptr += cnt;
    if (strcmp(token, "text_lost") == 0)
      ntok = sscanf(ptr, "%d%n", &stats->ps_drop, &cnt);
    else
      ntok = sscanf(ptr, "%d%n", &dummy, &cnt);
    if ((ntok != 1) || (cnt < 0))
      break;
    consumed += cnt;
    ptr += cnt;
  }

  return 0;
}

static int
usb_setdirection_linux(pcap_t *p, pcap_direction_t d)
{
  p->direction = d;
  return 0;
}


static int
usb_stats_linux_bin(pcap_t *handle, struct pcap_stat *stats)
{
  struct pcap_usb_linux *handlep = handle->priv;
  int ret;
  struct mon_bin_stats st;
  ret = ioctl(handle->fd, MON_IOCG_STATS, &st);
  if (ret < 0)
  {
    pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
        errno, "Can't read stats from fd %d", handle->fd);
    return -1;
  }

  stats->ps_recv = handlep->packets_read + st.queued;
  stats->ps_drop = st.dropped;
  stats->ps_ifdrop = 0;
  return 0;
}

/*
 * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
 * <linux-kernel-source>/drivers/usb/mon/mon_bin.c binary ABI
 */
static int
usb_read_linux_bin(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
{
  struct pcap_usb_linux *handlep = handle->priv;
  struct mon_bin_get info;
  int ret;
  struct pcap_pkthdr pkth;
  u_int clen = handle->snapshot - sizeof(pcap_usb_header);

  /* the usb header is going to be part of 'packet' data*/
  info.hdr = (pcap_usb_header*) handle->buffer;
  info.data = (u_char *)handle->buffer + sizeof(pcap_usb_header);
  info.data_len = clen;

  /* ignore interrupt system call errors */
  do {
    ret = ioctl(handle->fd, MON_IOCX_GET, &info);
    if (handle->break_loop)
    {
      handle->break_loop = 0;
      return -2;
    }
  } while ((ret == -1) && (errno == EINTR));
  if (ret < 0)
  {
    if (errno == EAGAIN)
      return 0; /* no data there */

    pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
        errno, "Can't read from fd %d", handle->fd);
    return -1;
  }

  /*
   * info.hdr->data_len is the number of bytes of isochronous
   * descriptors (if any) plus the number of bytes of data
   * provided.  There are no isochronous descriptors here,
   * because we're using the old 48-byte header.
   *
   * If info.hdr->data_flag is non-zero, there's no URB data;
   * info.hdr->urb_len is the size of the buffer into which
   * data is to be placed; it does not represent the amount
   * of data transferred.  If info.hdr->data_flag is zero,
   * there is URB data, and info.hdr->urb_len is the number
   * of bytes transmitted or received; it doesn't include
   * isochronous descriptors.
   *
   * The kernel may give us more data than the snaplen; if it did,
   * reduce the data length so that the total number of bytes we
   * tell our client we have is not greater than the snaplen.
   */
  if (info.hdr->data_len < clen)
    clen = info.hdr->data_len;
  info.hdr->data_len = clen;
  pkth.caplen = sizeof(pcap_usb_header) + clen;
  if (info.hdr->data_flag) {
    /*
     * No data; just base the on-the-wire length on
     * info.hdr->data_len (so that it's >= the captured
     * length).
     */
    pkth.len = sizeof(pcap_usb_header) + info.hdr->data_len;
  } else {
    /*
     * We got data; base the on-the-wire length on
     * info.hdr->urb_len, so that it includes data
     * discarded by the USB monitor device due to
     * its buffer being too small.
     */
    pkth.len = sizeof(pcap_usb_header) + info.hdr->urb_len;
  }
  pkth.ts.tv_sec = info.hdr->ts_sec;
  pkth.ts.tv_usec = info.hdr->ts_usec;

  if (handle->fcode.bf_insns == NULL ||
      bpf_filter(handle->fcode.bf_insns, handle->buffer,
        pkth.len, pkth.caplen)) {
    handlep->packets_read++;
    callback(user, &pkth, handle->buffer);
    return 1;
  }

  return 0; /* didn't pass filter */
}

/*
 * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
 * <linux-kernel-source>/drivers/usb/mon/mon_bin.c binary ABI
 */
#define VEC_SIZE 32
static int
usb_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
{
  struct pcap_usb_linux *handlep = handle->priv;
  struct mon_bin_mfetch fetch;
  int32_t vec[VEC_SIZE];
  struct pcap_pkthdr pkth;
  pcap_usb_header_mmapped* hdr;
  int nflush = 0;
  int packets = 0;
  u_int clen, max_clen;

  max_clen = handle->snapshot - sizeof(pcap_usb_header_mmapped);

  for (;;) {
    int i, ret;
    int limit = max_packets - packets;
    if (limit <= 0)
      limit = VEC_SIZE;
    if (limit > VEC_SIZE)
      limit = VEC_SIZE;

    /* try to fetch as many events as possible*/
    fetch.offvec = vec;
    fetch.nfetch = limit;
    fetch.nflush = nflush;
    /* ignore interrupt system call errors */
    do {
      ret = ioctl(handle->fd, MON_IOCX_MFETCH, &fetch);
      if (handle->break_loop)
      {
        handle->break_loop = 0;
        return -2;
      }
    } while ((ret == -1) && (errno == EINTR));
    if (ret < 0)
    {
      if (errno == EAGAIN)
        return 0; /* no data there */

      pcap_fmt_errmsg_for_errno(handle->errbuf,
          PCAP_ERRBUF_SIZE, errno, "Can't mfetch fd %d",
          handle->fd);
      return -1;
    }

    /* keep track of processed events, we will flush them later */
    nflush = fetch.nfetch;
    for (i=0; i<fetch.nfetch; ++i) {
      /* discard filler */
      hdr = (pcap_usb_header_mmapped*) &handlep->mmapbuf[vec[i]];
      if (hdr->event_type == '@')
        continue;

      /*
       * hdr->data_len is the number of bytes of
       * isochronous descriptors (if any) plus the
       * number of bytes of data provided.
       *
       * If hdr->data_flag is non-zero, there's no
       * URB data; hdr->urb_len is the size of the
       * buffer into which data is to be placed; it does
       * not represent the amount of data transferred.
       * If hdr->data_flag is zero, there is URB data,
       * and hdr->urb_len is the number of bytes
       * transmitted or received; it doesn't include
       * isochronous descriptors.
       *
       * The kernel may give us more data than the
       * snaplen; if it did, reduce the data length
       * so that the total number of bytes we
       * tell our client we have is not greater than
       * the snaplen.
       */
      clen = max_clen;
      if (hdr->data_len < clen)
        clen = hdr->data_len;
      pkth.caplen = sizeof(pcap_usb_header_mmapped) + clen;
      if (hdr->data_flag) {
        /*
         * No data; just base the on-the-wire length
         * on hdr->data_len (so that it's >= the
         * captured length).
         */
        pkth.len = sizeof(pcap_usb_header_mmapped) +
            hdr->data_len;
      } else {
        /*
         * We got data; base the on-the-wire length
         * on hdr->urb_len, so that it includes
         * data discarded by the USB monitor device
         * due to its buffer being too small.
         */
        pkth.len = sizeof(pcap_usb_header_mmapped) +
            (hdr->ndesc * sizeof (usb_isodesc)) + hdr->urb_len;
      }
      pkth.ts.tv_sec = hdr->ts_sec;
      pkth.ts.tv_usec = hdr->ts_usec;

      if (handle->fcode.bf_insns == NULL ||
          bpf_filter(handle->fcode.bf_insns, (u_char*) hdr,
            pkth.len, pkth.caplen)) {
        handlep->packets_read++;
        callback(user, &pkth, (u_char*) hdr);
        packets++;
      }
    }

    /* with max_packets specifying "unlimited" we stop afer the first chunk*/
    if (PACKET_COUNT_IS_UNLIMITED(max_packets) || (packets == max_packets))
      break;
  }

  /* flush pending events*/
  if (ioctl(handle->fd, MON_IOCH_MFLUSH, nflush) == -1) {
    pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
        errno, "Can't mflush fd %d", handle->fd);
    return -1;
  }
  return packets;
}

static void
usb_cleanup_linux_mmap(pcap_t* handle)
{
  struct pcap_usb_linux *handlep = handle->priv;

  /* if we have a memory-mapped buffer, unmap it */
  if (handlep->mmapbuf != NULL) {
    munmap(handlep->mmapbuf, handlep->mmapbuflen);
    handlep->mmapbuf = NULL;
  }
  pcap_cleanup_live_common(handle);
}

Coverage Report

Created: 2021-11-03 07:11