/*
   * 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 <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,
  		    "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, "USB 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.
  		 */
  		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;
  	}
  }
  
  static
  int usb_mmap(pcap_t* handle)
  {
  	struct pcap_usb_linux *handlep = handle->priv;
  	int len = ioctl(handle->fd, MON_IOCQ_RING_SIZE);
  	if (len < 0)
  		return 0;
  
  	handlep->mmapbuflen = len;
  	handlep->mmapbuf = mmap(0, handlep->mmapbuflen, PROT_READ,
  	    MAP_SHARED, handle->fd, 0);
  	return handlep->mmapbuf != MAP_FAILED;
  }
  
  #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];
  
  	/*
  	 * 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))
  		{
  			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;
  		}
  
  		/* can't mmap, use plain binary interface access */
  		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) {
  				/*
  				 * Is the problem that we didn't have
  				 * sufficient permission to open it?
  				 */
  				if (errno == EACCES) {
  					/*
  					 * Yes - return that error.
  					 */
  					return PCAP_ERROR_PERM_DENIED;
  				}
  
  				/*
  				 * No - was the problem something other
  				 * than "it doesn't exist"?
  				 */
  				if (errno != ENOENT) {
  					/*
  					 * Yes - return *that* error.
  					 */
  					pcap_fmt_errmsg_for_errno(handle->errbuf,
  					    PCAP_ERRBUF_SIZE, errno,
  					    "Can't open USB bus file %s",
  					    full_path);
  					return PCAP_ERROR;
  				}
  
  				/*
  				 * No.  Report that as "no such device".
  				 * (That could mean "no such USB bus"
  				 * or "monitoring not supported".)
  				 */
  				return PCAP_ERROR_NO_SUCH_DEVICE;
  			}
  		}
  
  		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, "inject 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;
  
  	/* 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, "nreaders") == 0)
  			ret = sscanf(ptr, "%d", &stats->ps_drop);
  		else
  			ret = sscanf(ptr, "%d", &dummy);
  		if (ntok != 1)
  			break;
  		consumed += cnt;
  		ptr += cnt;
  	}
  
  	stats->ps_recv = handlep->packets_read;
  	stats->ps_ifdrop = 0;
  	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;
  	}
  
  	/* we can get less that than really captured from kernel, depending on
  	 * snaplen, so adjust header accordingly */
  	if (info.hdr->data_len < clen)
  		clen = info.hdr->data_len;
  	info.hdr->data_len = clen;
  	pkth.caplen = clen + sizeof(pcap_usb_header);
  	pkth.len = info.hdr->data_len + sizeof(pcap_usb_header);
  	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* hdr;
  	int nflush = 0;
  	int packets = 0;
  	u_int clen, max_clen;
  
  	max_clen = handle->snapshot - sizeof(pcap_usb_header);
  
  	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*) &handlep->mmapbuf[vec[i]];
  			if (hdr->event_type == '@')
  				continue;
  
  			/* we can get less that than really captured from kernel, depending on
  	 		* snaplen, so adjust header accordingly */
  			clen = max_clen;
  			if (hdr->data_len < clen)
  				clen = hdr->data_len;
  
  			/* get packet info from header*/
  			pkth.caplen = clen + sizeof(pcap_usb_header_mmapped);
  			pkth.len = hdr->data_len + sizeof(pcap_usb_header_mmapped);
  			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);
  }