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      1 /*
      2  * Copyright (c) 2006 Paolo Abeni (Italy)
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *
      9  * 1. Redistributions of source code must retain the above copyright
     10  * notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  * notice, this list of conditions and the following disclaimer in the
     13  * documentation and/or other materials provided with the distribution.
     14  * 3. The name of the author may not be used to endorse or promote
     15  * products derived from this software without specific prior written
     16  * permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  *
     30  * USB sniffing API implementation for Linux platform
     31  * By Paolo Abeni <paolo.abeni (at) email.it>
     32  * Modifications: Kris Katterjohn <katterjohn (at) gmail.com>
     33  *
     34  */
     35 
     36 #ifdef HAVE_CONFIG_H
     37 #include <config.h>
     38 #endif
     39 
     40 #include "pcap-int.h"
     41 #include "pcap-usb-linux.h"
     42 #include "pcap/usb.h"
     43 
     44 #ifdef NEED_STRERROR_H
     45 #include "strerror.h"
     46 #endif
     47 
     48 #include <ctype.h>
     49 #include <errno.h>
     50 #include <stdlib.h>
     51 #include <unistd.h>
     52 #include <fcntl.h>
     53 #include <string.h>
     54 #include <dirent.h>
     55 #include <byteswap.h>
     56 #include <netinet/in.h>
     57 #include <sys/ioctl.h>
     58 #include <sys/mman.h>
     59 #include <sys/utsname.h>
     60 #ifdef HAVE_LINUX_USBDEVICE_FS_H
     61 /*
     62  * We might need <linux/compiler.h> to define __user for
     63  * <linux/usbdevice_fs.h>.
     64  */
     65 #ifdef HAVE_LINUX_COMPILER_H
     66 #include <linux/compiler.h>
     67 #endif /* HAVE_LINUX_COMPILER_H */
     68 #include <linux/usbdevice_fs.h>
     69 #endif /* HAVE_LINUX_USBDEVICE_FS_H */
     70 
     71 #define USB_IFACE "usbmon"
     72 #define USB_TEXT_DIR_OLD "/sys/kernel/debug/usbmon"
     73 #define USB_TEXT_DIR "/sys/kernel/debug/usb/usbmon"
     74 #define SYS_USB_BUS_DIR "/sys/bus/usb/devices"
     75 #define PROC_USB_BUS_DIR "/proc/bus/usb"
     76 #define USB_LINE_LEN 4096
     77 
     78 #if __BYTE_ORDER == __LITTLE_ENDIAN
     79 #define htols(s) s
     80 #define htoll(l) l
     81 #define htol64(ll) ll
     82 #else
     83 #define htols(s) bswap_16(s)
     84 #define htoll(l) bswap_32(l)
     85 #define htol64(ll) bswap_64(ll)
     86 #endif
     87 
     88 struct mon_bin_stats {
     89 	uint32_t queued;
     90 	uint32_t dropped;
     91 };
     92 
     93 struct mon_bin_get {
     94 	pcap_usb_header *hdr;
     95 	void *data;
     96 	size_t data_len;   /* Length of data (can be zero) */
     97 };
     98 
     99 struct mon_bin_mfetch {
    100 	int32_t *offvec;   /* Vector of events fetched */
    101 	int32_t nfetch;    /* Number of events to fetch (out: fetched) */
    102 	int32_t nflush;    /* Number of events to flush */
    103 };
    104 
    105 #define MON_IOC_MAGIC 0x92
    106 
    107 #define MON_IOCQ_URB_LEN _IO(MON_IOC_MAGIC, 1)
    108 #define MON_IOCX_URB  _IOWR(MON_IOC_MAGIC, 2, struct mon_bin_hdr)
    109 #define MON_IOCG_STATS _IOR(MON_IOC_MAGIC, 3, struct mon_bin_stats)
    110 #define MON_IOCT_RING_SIZE _IO(MON_IOC_MAGIC, 4)
    111 #define MON_IOCQ_RING_SIZE _IO(MON_IOC_MAGIC, 5)
    112 #define MON_IOCX_GET   _IOW(MON_IOC_MAGIC, 6, struct mon_bin_get)
    113 #define MON_IOCX_MFETCH _IOWR(MON_IOC_MAGIC, 7, struct mon_bin_mfetch)
    114 #define MON_IOCH_MFLUSH _IO(MON_IOC_MAGIC, 8)
    115 
    116 #define MON_BIN_SETUP 	0x1 /* setup hdr is present*/
    117 #define MON_BIN_SETUP_ZERO 	0x2 /* setup buffer is not available */
    118 #define MON_BIN_DATA_ZERO 	0x4 /* data buffer is not available */
    119 #define MON_BIN_ERROR 	0x8
    120 
    121 /*
    122  * Private data for capturing on Linux USB.
    123  */
    124 struct pcap_usb_linux {
    125 	u_char *mmapbuf;	/* memory-mapped region pointer */
    126 	size_t mmapbuflen;	/* size of region */
    127 	int bus_index;
    128 	u_int packets_read;
    129 };
    130 
    131 /* forward declaration */
    132 static int usb_activate(pcap_t *);
    133 static int usb_stats_linux(pcap_t *, struct pcap_stat *);
    134 static int usb_stats_linux_bin(pcap_t *, struct pcap_stat *);
    135 static int usb_read_linux(pcap_t *, int , pcap_handler , u_char *);
    136 static int usb_read_linux_bin(pcap_t *, int , pcap_handler , u_char *);
    137 static int usb_read_linux_mmap(pcap_t *, int , pcap_handler , u_char *);
    138 static int usb_inject_linux(pcap_t *, const void *, size_t);
    139 static int usb_setdirection_linux(pcap_t *, pcap_direction_t);
    140 static void usb_cleanup_linux_mmap(pcap_t *);
    141 
    142 static int
    143 have_binary_usbmon(void)
    144 {
    145 	struct utsname utsname;
    146 	char *version_component, *endp;
    147 	int major, minor, subminor;
    148 
    149 	if (uname(&utsname) == 0) {
    150 		/*
    151 		 * 2.6.21 is the first release with the binary-mode
    152 		 * USB monitoring.
    153 		 */
    154 		version_component = utsname.release;
    155 		major = strtol(version_component, &endp, 10);
    156 		if (endp != version_component && *endp == '.') {
    157 			/*
    158 			 * OK, that was a valid major version.
    159 			 * Is it 3 or greater?  If so, we have binary
    160 			 * mode support.
    161 			 */
    162 			if (major >= 3)
    163 				return 1;
    164 
    165 			/*
    166 			 * Is it 1 or less?  If so, we don't have binary
    167 			 * mode support.  (In fact, we don't have any
    168 			 * USB monitoring....)
    169 			 */
    170 			if (major <= 1)
    171 				return 0;
    172 		}
    173 
    174 		/*
    175 		 * OK, this is a 2.x kernel.
    176 		 * What's the minor version?
    177 		 */
    178 		version_component = endp + 1;
    179 		minor = strtol(version_component, &endp, 10);
    180 		if (endp != version_component &&
    181 		    (*endp == '.' || *endp == '\0')) {
    182 			/*
    183 			 * OK, that was a valid minor version.
    184 			 * Is is 2.6 or later?  (There shouldn't be a
    185 			 * "later", as 2.6.x went to 3.x, but we'll
    186 			 * check anyway.)
    187 			 */
    188 			if (minor < 6) {
    189 				/*
    190 				 * No, so no binary support (did 2.4 have
    191 				 * any USB monitoring at all?)
    192 				 */
    193 				return 0;
    194 			}
    195 
    196 			/*
    197 			 * OK, this is a 2.6.x kernel.
    198 			 * What's the subminor version?
    199 			 */
    200 			version_component = endp + 1;
    201 			subminor = strtol(version_component, &endp, 10);
    202 			if (endp != version_component &&
    203 			    (*endp == '.' || *endp == '\0')) {
    204 				/*
    205 				 * OK, that was a valid subminor version.
    206 				 * Is it 21 or greater?
    207 				 */
    208 				if (subminor >= 21) {
    209 					/*
    210 					 * Yes - we have binary mode
    211 					 * support.
    212 					 */
    213 					return 1;
    214 				}
    215 			}
    216 		}
    217 	}
    218 
    219 	/*
    220 	 * Either uname() failed, in which case we just say "no binary
    221 	 * mode support", or we don't have binary mode support.
    222 	 */
    223 	return 0;
    224 }
    225 
    226 /* facility to add an USB device to the device list*/
    227 static int
    228 usb_dev_add(pcap_if_list_t *devlistp, int n, char *err_str)
    229 {
    230 	char dev_name[10];
    231 	char dev_descr[30];
    232 	pcap_snprintf(dev_name, 10, USB_IFACE"%d", n);
    233 	/*
    234 	 * XXX - is there any notion of "up" and "running"?
    235 	 */
    236 	if (n == 0) {
    237 		/*
    238 		 * As this refers to all buses, there's no notion of
    239 		 * "connected" vs. "disconnected", as that's a property
    240 		 * that would apply to a particular USB interface.
    241 		 */
    242 		if (add_dev(devlistp, dev_name,
    243 		    PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
    244 		    "All USB buses", err_str) == NULL)
    245 			return -1;
    246 	} else {
    247 		/*
    248 		 * XXX - is there a way to determine whether anything's
    249 		 * plugged into this bus interface or not, and set
    250 		 * PCAP_IF_CONNECTION_STATUS_CONNECTED or
    251 		 * PCAP_IF_CONNECTION_STATUS_DISCONNECTED?
    252 		 */
    253 		pcap_snprintf(dev_descr, 30, "USB bus number %d", n);
    254 		if (add_dev(devlistp, dev_name, 0, dev_descr, err_str) == NULL)
    255 			return -1;
    256 	}
    257 
    258 	return 0;
    259 }
    260 
    261 int
    262 usb_findalldevs(pcap_if_list_t *devlistp, char *err_str)
    263 {
    264 	char usb_mon_dir[PATH_MAX];
    265 	char *usb_mon_prefix;
    266 	size_t usb_mon_prefix_len;
    267 	struct dirent* data;
    268 	int ret = 0;
    269 	DIR* dir;
    270 	int n;
    271 	char* name;
    272 	size_t len;
    273 
    274 	if (have_binary_usbmon()) {
    275 		/*
    276 		 * We have binary-mode support.
    277 		 * What do the device names look like?
    278 		 * Split LINUX_USB_MON_DEV into a directory that we'll
    279 		 * scan and a file name prefix that we'll check for.
    280 		 */
    281 		strlcpy(usb_mon_dir, LINUX_USB_MON_DEV, sizeof usb_mon_dir);
    282 		usb_mon_prefix = strrchr(usb_mon_dir, '/');
    283 		if (usb_mon_prefix == NULL) {
    284 			/*
    285 			 * This "shouldn't happen".  Just give up if it
    286 			 * does.
    287 			 */
    288 			return 0;
    289 		}
    290 		*usb_mon_prefix++ = '\0';
    291 		usb_mon_prefix_len = strlen(usb_mon_prefix);
    292 
    293 		/*
    294 		 * Open the directory and scan it.
    295 		 */
    296 		dir = opendir(usb_mon_dir);
    297 		if (dir != NULL) {
    298 			while ((ret == 0) && ((data = readdir(dir)) != 0)) {
    299 				name = data->d_name;
    300 
    301 				/*
    302 				 * Is this a usbmon device?
    303 				 */
    304 				if (strncmp(name, usb_mon_prefix, usb_mon_prefix_len) != 0)
    305 					continue;	/* no */
    306 
    307 				/*
    308 				 * What's the device number?
    309 				 */
    310 				if (sscanf(&name[usb_mon_prefix_len], "%d", &n) == 0)
    311 					continue;	/* failed */
    312 
    313 				ret = usb_dev_add(devlistp, n, err_str);
    314 			}
    315 
    316 			closedir(dir);
    317 		}
    318 		return 0;
    319 	} else {
    320 		/*
    321 		 * We have only text mode support.
    322 		 * We don't look for the text devices because we can't
    323 		 * look for them without root privileges, and we don't
    324 		 * want to require root privileges to enumerate devices
    325 		 * (we want to let the user to try a device and get
    326 		 * an error, rather than seeing no devices and asking
    327 		 * "why am I not seeing devices" and forcing a long
    328 		 * process of poking to figure out whether it's "no
    329 		 * privileges" or "your kernel is too old" or "the
    330 		 * usbmon module isn't loaded" or...).
    331 		 *
    332 		 * Instead, we look to see what buses we have.
    333 		 * If the kernel is so old that it doesn't have
    334 		 * binary-mode support, it's also so old that
    335 		 * it doesn't have a "scan all buses" device.
    336 		 *
    337 		 * First, try scanning sysfs USB bus directory.
    338 		 */
    339 		dir = opendir(SYS_USB_BUS_DIR);
    340 		if (dir != NULL) {
    341 			while ((ret == 0) && ((data = readdir(dir)) != 0)) {
    342 				name = data->d_name;
    343 
    344 				if (strncmp(name, "usb", 3) != 0)
    345 					continue;
    346 
    347 				if (sscanf(&name[3], "%d", &n) == 0)
    348 					continue;
    349 
    350 				ret = usb_dev_add(devlistp, n, err_str);
    351 			}
    352 
    353 			closedir(dir);
    354 			return 0;
    355 		}
    356 
    357 		/* That didn't work; try scanning procfs USB bus directory. */
    358 		dir = opendir(PROC_USB_BUS_DIR);
    359 		if (dir != NULL) {
    360 			while ((ret == 0) && ((data = readdir(dir)) != 0)) {
    361 				name = data->d_name;
    362 				len = strlen(name);
    363 
    364 				/* if this file name does not end with a number it's not of our interest */
    365 				if ((len < 1) || !isdigit(name[--len]))
    366 					continue;
    367 				while (isdigit(name[--len]));
    368 				if (sscanf(&name[len+1], "%d", &n) != 1)
    369 					continue;
    370 
    371 				ret = usb_dev_add(devlistp, n, err_str);
    372 			}
    373 
    374 			closedir(dir);
    375 			return ret;
    376 		}
    377 
    378 		/* neither of them worked */
    379 		return 0;
    380 	}
    381 }
    382 
    383 static
    384 int usb_mmap(pcap_t* handle)
    385 {
    386 	struct pcap_usb_linux *handlep = handle->priv;
    387 	int len = ioctl(handle->fd, MON_IOCQ_RING_SIZE);
    388 	if (len < 0)
    389 		return 0;
    390 
    391 	handlep->mmapbuflen = len;
    392 	handlep->mmapbuf = mmap(0, handlep->mmapbuflen, PROT_READ,
    393 	    MAP_SHARED, handle->fd, 0);
    394 	return handlep->mmapbuf != MAP_FAILED;
    395 }
    396 
    397 #ifdef HAVE_LINUX_USBDEVICE_FS_H
    398 
    399 #define CTRL_TIMEOUT    (5*1000)        /* milliseconds */
    400 
    401 #define USB_DIR_IN		0x80
    402 #define USB_TYPE_STANDARD	0x00
    403 #define USB_RECIP_DEVICE	0x00
    404 
    405 #define USB_REQ_GET_DESCRIPTOR	6
    406 
    407 #define USB_DT_DEVICE		1
    408 
    409 /* probe the descriptors of the devices attached to the bus */
    410 /* the descriptors will end up in the captured packet stream */
    411 /* and be decoded by external apps like wireshark */
    412 /* without these identifying probes packet data can't be fully decoded */
    413 static void
    414 probe_devices(int bus)
    415 {
    416 	struct usbdevfs_ctrltransfer ctrl;
    417 	struct dirent* data;
    418 	int ret = 0;
    419 	char buf[sizeof("/dev/bus/usb/000/") + NAME_MAX];
    420 	DIR* dir;
    421 
    422 	/* scan usb bus directories for device nodes */
    423 	pcap_snprintf(buf, sizeof(buf), "/dev/bus/usb/%03d", bus);
    424 	dir = opendir(buf);
    425 	if (!dir)
    426 		return;
    427 
    428 	while ((ret >= 0) && ((data = readdir(dir)) != 0)) {
    429 		int fd;
    430 		char* name = data->d_name;
    431 
    432 		if (name[0] == '.')
    433 			continue;
    434 
    435 		pcap_snprintf(buf, sizeof(buf), "/dev/bus/usb/%03d/%s", bus, data->d_name);
    436 
    437 		fd = open(buf, O_RDWR);
    438 		if (fd == -1)
    439 			continue;
    440 
    441 		/*
    442 		 * Sigh.  Different kernels have different member names
    443 		 * for this structure.
    444 		 */
    445 #ifdef HAVE_STRUCT_USBDEVFS_CTRLTRANSFER_BREQUESTTYPE
    446 		ctrl.bRequestType = USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE;
    447 		ctrl.bRequest = USB_REQ_GET_DESCRIPTOR;
    448 		ctrl.wValue = USB_DT_DEVICE << 8;
    449 		ctrl.wIndex = 0;
    450  		ctrl.wLength = sizeof(buf);
    451 #else
    452 		ctrl.requesttype = USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE;
    453 		ctrl.request = USB_REQ_GET_DESCRIPTOR;
    454 		ctrl.value = USB_DT_DEVICE << 8;
    455 		ctrl.index = 0;
    456  		ctrl.length = sizeof(buf);
    457 #endif
    458 		ctrl.data = buf;
    459 		ctrl.timeout = CTRL_TIMEOUT;
    460 
    461 		ret = ioctl(fd, USBDEVFS_CONTROL, &ctrl);
    462 
    463 		close(fd);
    464 	}
    465 	closedir(dir);
    466 }
    467 #endif /* HAVE_LINUX_USBDEVICE_FS_H */
    468 
    469 pcap_t *
    470 usb_create(const char *device, char *ebuf, int *is_ours)
    471 {
    472 	const char *cp;
    473 	char *cpend;
    474 	long devnum;
    475 	pcap_t *p;
    476 
    477 	/* Does this look like a USB monitoring device? */
    478 	cp = strrchr(device, '/');
    479 	if (cp == NULL)
    480 		cp = device;
    481 	/* Does it begin with USB_IFACE? */
    482 	if (strncmp(cp, USB_IFACE, sizeof USB_IFACE - 1) != 0) {
    483 		/* Nope, doesn't begin with USB_IFACE */
    484 		*is_ours = 0;
    485 		return NULL;
    486 	}
    487 	/* Yes - is USB_IFACE followed by a number? */
    488 	cp += sizeof USB_IFACE - 1;
    489 	devnum = strtol(cp, &cpend, 10);
    490 	if (cpend == cp || *cpend != '\0') {
    491 		/* Not followed by a number. */
    492 		*is_ours = 0;
    493 		return NULL;
    494 	}
    495 	if (devnum < 0) {
    496 		/* Followed by a non-valid number. */
    497 		*is_ours = 0;
    498 		return NULL;
    499 	}
    500 
    501 	/* OK, it's probably ours. */
    502 	*is_ours = 1;
    503 
    504 	p = pcap_create_common(ebuf, sizeof (struct pcap_usb_linux));
    505 	if (p == NULL)
    506 		return (NULL);
    507 
    508 	p->activate_op = usb_activate;
    509 	return (p);
    510 }
    511 
    512 static int
    513 usb_activate(pcap_t* handle)
    514 {
    515 	struct pcap_usb_linux *handlep = handle->priv;
    516 	char 		full_path[USB_LINE_LEN];
    517 
    518 	/*
    519 	 * Turn a negative snapshot value (invalid), a snapshot value of
    520 	 * 0 (unspecified), or a value bigger than the normal maximum
    521 	 * value, into the maximum allowed value.
    522 	 *
    523 	 * If some application really *needs* a bigger snapshot
    524 	 * length, we should just increase MAXIMUM_SNAPLEN.
    525 	 */
    526 	if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN)
    527 		handle->snapshot = MAXIMUM_SNAPLEN;
    528 
    529 	/* Initialize some components of the pcap structure. */
    530 	handle->bufsize = handle->snapshot;
    531 	handle->offset = 0;
    532 	handle->linktype = DLT_USB_LINUX;
    533 
    534 	handle->inject_op = usb_inject_linux;
    535 	handle->setfilter_op = install_bpf_program; /* no kernel filtering */
    536 	handle->setdirection_op = usb_setdirection_linux;
    537 	handle->set_datalink_op = NULL;	/* can't change data link type */
    538 	handle->getnonblock_op = pcap_getnonblock_fd;
    539 	handle->setnonblock_op = pcap_setnonblock_fd;
    540 
    541 	/*get usb bus index from device name */
    542 	if (sscanf(handle->opt.device, USB_IFACE"%d", &handlep->bus_index) != 1)
    543 	{
    544 		pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
    545 			"Can't get USB bus index from %s", handle->opt.device);
    546 		return PCAP_ERROR;
    547 	}
    548 
    549 	if (have_binary_usbmon())
    550 	{
    551 		/*
    552 		 * We have binary-mode support.
    553 		 * Try to open the binary interface.
    554 		 */
    555 		pcap_snprintf(full_path, USB_LINE_LEN, LINUX_USB_MON_DEV"%d", handlep->bus_index);
    556 		handle->fd = open(full_path, O_RDONLY, 0);
    557 		if (handle->fd < 0)
    558 		{
    559 			/*
    560 			 * The attempt failed; why?
    561 			 */
    562 			switch (errno) {
    563 
    564 			case ENOENT:
    565 				/*
    566 				 * The device doesn't exist.
    567 				 * That could either mean that there's
    568 				 * no support for monitoring USB buses
    569 				 * (which probably means "the usbmon
    570 				 * module isn't loaded") or that there
    571 				 * is but that *particular* device
    572 				 * doesn't exist (no "scan all buses"
    573 				 * device if the bus index is 0, no
    574 				 * such bus if the bus index isn't 0).
    575 				 */
    576 				return PCAP_ERROR_NO_SUCH_DEVICE;
    577 
    578 			case EACCES:
    579 				/*
    580 				 * We didn't have permission to open it.
    581 				 */
    582 				return PCAP_ERROR_PERM_DENIED;
    583 
    584 			default:
    585 				/*
    586 				 * Something went wrong.
    587 				 */
    588 				pcap_fmt_errmsg_for_errno(handle->errbuf,
    589 				    PCAP_ERRBUF_SIZE, errno,
    590 				    "Can't open USB bus file %s", full_path);
    591 				return PCAP_ERROR;
    592 			}
    593 		}
    594 
    595 		if (handle->opt.rfmon)
    596 		{
    597 			/*
    598 			 * Monitor mode doesn't apply to USB devices.
    599 			 */
    600 			close(handle->fd);
    601 			return PCAP_ERROR_RFMON_NOTSUP;
    602 		}
    603 
    604 		/* try to use fast mmap access */
    605 		if (usb_mmap(handle))
    606 		{
    607 			handle->linktype = DLT_USB_LINUX_MMAPPED;
    608 			handle->stats_op = usb_stats_linux_bin;
    609 			handle->read_op = usb_read_linux_mmap;
    610 			handle->cleanup_op = usb_cleanup_linux_mmap;
    611 #ifdef HAVE_LINUX_USBDEVICE_FS_H
    612 			probe_devices(handlep->bus_index);
    613 #endif
    614 
    615 			/*
    616 			 * "handle->fd" is a real file, so
    617 			 * "select()" and "poll()" work on it.
    618 			 */
    619 			handle->selectable_fd = handle->fd;
    620 			return 0;
    621 		}
    622 
    623 		/* can't mmap, use plain binary interface access */
    624 		handle->stats_op = usb_stats_linux_bin;
    625 		handle->read_op = usb_read_linux_bin;
    626 #ifdef HAVE_LINUX_USBDEVICE_FS_H
    627 		probe_devices(handlep->bus_index);
    628 #endif
    629 	}
    630 	else {
    631 		/*
    632 		 * We don't have binary mode support.
    633 		 * Try opening the text-mode device.
    634 		 */
    635 		pcap_snprintf(full_path, USB_LINE_LEN, USB_TEXT_DIR"/%dt", handlep->bus_index);
    636 		handle->fd = open(full_path, O_RDONLY, 0);
    637 		if (handle->fd < 0)
    638 		{
    639 			if (errno == ENOENT)
    640 			{
    641 				/*
    642 				 * Not found at the new location; try
    643 				 * the old location.
    644 				 */
    645 				pcap_snprintf(full_path, USB_LINE_LEN, USB_TEXT_DIR_OLD"/%dt", handlep->bus_index);
    646 				handle->fd = open(full_path, O_RDONLY, 0);
    647 			}
    648 			if (handle->fd < 0) {
    649 				/*
    650 				 * Is the problem that we didn't have
    651 				 * sufficient permission to open it?
    652 				 */
    653 				if (errno == EACCES) {
    654 					/*
    655 					 * Yes - return that error.
    656 					 */
    657 					return PCAP_ERROR_PERM_DENIED;
    658 				}
    659 
    660 				/*
    661 				 * No - was the problem something other
    662 				 * than "it doesn't exist"?
    663 				 */
    664 				if (errno != ENOENT) {
    665 					/*
    666 					 * Yes - return *that* error.
    667 					 */
    668 					pcap_fmt_errmsg_for_errno(handle->errbuf,
    669 					    PCAP_ERRBUF_SIZE, errno,
    670 					    "Can't open USB bus file %s",
    671 					    full_path);
    672 					return PCAP_ERROR;
    673 				}
    674 
    675 				/*
    676 				 * No.  Report that as "no such device".
    677 				 * (That could mean "no such USB bus"
    678 				 * or "monitoring not supported".)
    679 				 */
    680 				return PCAP_ERROR_NO_SUCH_DEVICE;
    681 			}
    682 		}
    683 
    684 		if (handle->opt.rfmon)
    685 		{
    686 			/*
    687 			 * Monitor mode doesn't apply to USB devices.
    688 			 */
    689 			close(handle->fd);
    690 			return PCAP_ERROR_RFMON_NOTSUP;
    691 		}
    692 
    693 		handle->stats_op = usb_stats_linux;
    694 		handle->read_op = usb_read_linux;
    695 	}
    696 
    697 	/*
    698 	 * "handle->fd" is a real file, so "select()" and "poll()"
    699 	 * work on it.
    700 	 */
    701 	handle->selectable_fd = handle->fd;
    702 
    703 	/* for plain binary access and text access we need to allocate the read
    704 	 * buffer */
    705 	handle->buffer = malloc(handle->bufsize);
    706 	if (!handle->buffer) {
    707 		pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
    708 		    errno, "malloc");
    709 		close(handle->fd);
    710 		return PCAP_ERROR;
    711 	}
    712 	return 0;
    713 }
    714 
    715 static inline int
    716 ascii_to_int(char c)
    717 {
    718 	return c < 'A' ? c- '0': ((c<'a') ? c - 'A' + 10: c-'a'+10);
    719 }
    720 
    721 /*
    722  * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
    723  * <linux-kernel-source>/drivers/usb/mon/mon_text.c for urb string
    724  * format description
    725  */
    726 static int
    727 usb_read_linux(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
    728 {
    729 	/* see:
    730 	* /usr/src/linux/Documentation/usb/usbmon.txt
    731 	* for message format
    732 	*/
    733 	struct pcap_usb_linux *handlep = handle->priv;
    734 	unsigned timestamp;
    735 	int tag, cnt, ep_num, dev_addr, dummy, ret, urb_len, data_len;
    736 	char etype, pipeid1, pipeid2, status[16], urb_tag, line[USB_LINE_LEN];
    737 	char *string = line;
    738 	u_char * rawdata = handle->buffer;
    739 	struct pcap_pkthdr pkth;
    740 	pcap_usb_header* uhdr = (pcap_usb_header*)handle->buffer;
    741 	u_char urb_transfer=0;
    742 	int incoming=0;
    743 
    744 	/* ignore interrupt system call errors */
    745 	do {
    746 		ret = read(handle->fd, line, USB_LINE_LEN - 1);
    747 		if (handle->break_loop)
    748 		{
    749 			handle->break_loop = 0;
    750 			return -2;
    751 		}
    752 	} while ((ret == -1) && (errno == EINTR));
    753 	if (ret < 0)
    754 	{
    755 		if (errno == EAGAIN)
    756 			return 0;	/* no data there */
    757 
    758 		pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
    759 		    errno, "Can't read from fd %d", handle->fd);
    760 		return -1;
    761 	}
    762 
    763 	/* read urb header; %n argument may increment return value, but it's
    764 	* not mandatory, so does not count on it*/
    765 	string[ret] = 0;
    766 	ret = sscanf(string, "%x %d %c %c%c:%d:%d %s%n", &tag, &timestamp, &etype,
    767 		&pipeid1, &pipeid2, &dev_addr, &ep_num, status,
    768 		&cnt);
    769 	if (ret < 8)
    770 	{
    771 		pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
    772 		    "Can't parse USB bus message '%s', too few tokens (expected 8 got %d)",
    773 		    string, ret);
    774 		return -1;
    775 	}
    776 	uhdr->id = tag;
    777 	uhdr->device_address = dev_addr;
    778 	uhdr->bus_id = handlep->bus_index;
    779 	uhdr->status = 0;
    780 	string += cnt;
    781 
    782 	/* don't use usbmon provided timestamp, since it have low precision*/
    783 	if (gettimeofday(&pkth.ts, NULL) < 0)
    784 	{
    785 		pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
    786 		    errno, "Can't get timestamp for message '%s'", string);
    787 		return -1;
    788 	}
    789 	uhdr->ts_sec = pkth.ts.tv_sec;
    790 	uhdr->ts_usec = pkth.ts.tv_usec;
    791 
    792 	/* parse endpoint information */
    793 	if (pipeid1 == 'C')
    794 		urb_transfer = URB_CONTROL;
    795 	else if (pipeid1 == 'Z')
    796 		urb_transfer = URB_ISOCHRONOUS;
    797 	else if (pipeid1 == 'I')
    798 		urb_transfer = URB_INTERRUPT;
    799 	else if (pipeid1 == 'B')
    800 		urb_transfer = URB_BULK;
    801 	if (pipeid2 == 'i') {
    802 		ep_num |= URB_TRANSFER_IN;
    803 		incoming = 1;
    804 	}
    805 	if (etype == 'C')
    806 		incoming = !incoming;
    807 
    808 	/* direction check*/
    809 	if (incoming)
    810 	{
    811 		if (handle->direction == PCAP_D_OUT)
    812 			return 0;
    813 	}
    814 	else
    815 		if (handle->direction == PCAP_D_IN)
    816 			return 0;
    817 	uhdr->event_type = etype;
    818 	uhdr->transfer_type = urb_transfer;
    819 	uhdr->endpoint_number = ep_num;
    820 	pkth.caplen = sizeof(pcap_usb_header);
    821 	rawdata += sizeof(pcap_usb_header);
    822 
    823 	/* check if this is a setup packet */
    824 	ret = sscanf(status, "%d", &dummy);
    825 	if (ret != 1)
    826 	{
    827 		/* this a setup packet, setup data can be filled with underscore if
    828 		* usbmon has not been able to read them, so we must parse this fields as
    829 		* strings */
    830 		pcap_usb_setup* shdr;
    831 		char str1[3], str2[3], str3[5], str4[5], str5[5];
    832 		ret = sscanf(string, "%s %s %s %s %s%n", str1, str2, str3, str4,
    833 		str5, &cnt);
    834 		if (ret < 5)
    835 		{
    836 			pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
    837 				"Can't parse USB bus message '%s', too few tokens (expected 5 got %d)",
    838 				string, ret);
    839 			return -1;
    840 		}
    841 		string += cnt;
    842 
    843 		/* try to convert to corresponding integer */
    844 		shdr = &uhdr->setup;
    845 		shdr->bmRequestType = strtoul(str1, 0, 16);
    846 		shdr->bRequest = strtoul(str2, 0, 16);
    847 		shdr->wValue = htols(strtoul(str3, 0, 16));
    848 		shdr->wIndex = htols(strtoul(str4, 0, 16));
    849 		shdr->wLength = htols(strtoul(str5, 0, 16));
    850 
    851 		uhdr->setup_flag = 0;
    852 	}
    853 	else
    854 		uhdr->setup_flag = 1;
    855 
    856 	/* read urb data */
    857 	ret = sscanf(string, " %d%n", &urb_len, &cnt);
    858 	if (ret < 1)
    859 	{
    860 		pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
    861 		  "Can't parse urb length from '%s'", string);
    862 		return -1;
    863 	}
    864 	string += cnt;
    865 
    866 	/* urb tag is not present if urb length is 0, so we can stop here
    867 	 * text parsing */
    868 	pkth.len = urb_len+pkth.caplen;
    869 	uhdr->urb_len = urb_len;
    870 	uhdr->data_flag = 1;
    871 	data_len = 0;
    872 	if (uhdr->urb_len == 0)
    873 		goto got;
    874 
    875 	/* check for data presence; data is present if and only if urb tag is '=' */
    876 	if (sscanf(string, " %c", &urb_tag) != 1)
    877 	{
    878 		pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
    879 			"Can't parse urb tag from '%s'", string);
    880 		return -1;
    881 	}
    882 
    883 	if (urb_tag != '=')
    884 		goto got;
    885 
    886 	/* skip urb tag and following space */
    887 	string += 3;
    888 
    889 	/* if we reach this point we got some urb data*/
    890 	uhdr->data_flag = 0;
    891 
    892 	/* read all urb data; if urb length is greater then the usbmon internal
    893 	 * buffer length used by the kernel to spool the URB, we get only
    894 	 * a partial information.
    895 	 * At least until linux 2.6.17 there is no way to set usbmon intenal buffer
    896 	 * length and default value is 130. */
    897 	while ((string[0] != 0) && (string[1] != 0) && (pkth.caplen < (bpf_u_int32)handle->snapshot))
    898 	{
    899 		rawdata[0] = ascii_to_int(string[0]) * 16 + ascii_to_int(string[1]);
    900 		rawdata++;
    901 		string+=2;
    902 		if (string[0] == ' ')
    903 			string++;
    904 		pkth.caplen++;
    905 		data_len++;
    906 	}
    907 
    908 got:
    909 	uhdr->data_len = data_len;
    910 	if (pkth.caplen > (bpf_u_int32)handle->snapshot)
    911 		pkth.caplen = (bpf_u_int32)handle->snapshot;
    912 
    913 	if (handle->fcode.bf_insns == NULL ||
    914 	    bpf_filter(handle->fcode.bf_insns, handle->buffer,
    915 	      pkth.len, pkth.caplen)) {
    916 		handlep->packets_read++;
    917 		callback(user, &pkth, handle->buffer);
    918 		return 1;
    919 	}
    920 	return 0;	/* didn't pass filter */
    921 }
    922 
    923 static int
    924 usb_inject_linux(pcap_t *handle, const void *buf _U_, size_t size _U_)
    925 {
    926 	pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on "
    927 		"USB devices");
    928 	return (-1);
    929 }
    930 
    931 static int
    932 usb_stats_linux(pcap_t *handle, struct pcap_stat *stats)
    933 {
    934 	struct pcap_usb_linux *handlep = handle->priv;
    935 	int dummy, ret, consumed, cnt;
    936 	char string[USB_LINE_LEN];
    937 	char token[USB_LINE_LEN];
    938 	char * ptr = string;
    939 	int fd;
    940 
    941 	pcap_snprintf(string, USB_LINE_LEN, USB_TEXT_DIR"/%ds", handlep->bus_index);
    942 	fd = open(string, O_RDONLY, 0);
    943 	if (fd < 0)
    944 	{
    945 		if (errno == ENOENT)
    946 		{
    947 			/*
    948 			 * Not found at the new location; try the old
    949 			 * location.
    950 			 */
    951 			pcap_snprintf(string, USB_LINE_LEN, USB_TEXT_DIR_OLD"/%ds", handlep->bus_index);
    952 			fd = open(string, O_RDONLY, 0);
    953 		}
    954 		if (fd < 0) {
    955 			pcap_fmt_errmsg_for_errno(handle->errbuf,
    956 			    PCAP_ERRBUF_SIZE, errno,
    957 			    "Can't open USB stats file %s", string);
    958 			return -1;
    959 		}
    960 	}
    961 
    962 	/* read stats line */
    963 	do {
    964 		ret = read(fd, string, USB_LINE_LEN-1);
    965 	} while ((ret == -1) && (errno == EINTR));
    966 	close(fd);
    967 
    968 	if (ret < 0)
    969 	{
    970 		pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
    971 			"Can't read stats from fd %d ", fd);
    972 		return -1;
    973 	}
    974 	string[ret] = 0;
    975 
    976 	/* extract info on dropped urbs */
    977 	for (consumed=0; consumed < ret; ) {
    978 		/* from the sscanf man page:
    979  		 * The C standard says: "Execution of a %n directive does
    980  		 * not increment the assignment count returned at the completion
    981 		 * of  execution" but the Corrigendum seems to contradict this.
    982 		 * Do not make any assumptions on the effect of %n conversions
    983 		 * on the return value and explicitly check for cnt assignmet*/
    984 		int ntok;
    985 
    986 		cnt = -1;
    987 		ntok = sscanf(ptr, "%s%n", token, &cnt);
    988 		if ((ntok < 1) || (cnt < 0))
    989 			break;
    990 		consumed += cnt;
    991 		ptr += cnt;
    992 		if (strcmp(token, "nreaders") == 0)
    993 			ret = sscanf(ptr, "%d", &stats->ps_drop);
    994 		else
    995 			ret = sscanf(ptr, "%d", &dummy);
    996 		if (ntok != 1)
    997 			break;
    998 		consumed += cnt;
    999 		ptr += cnt;
   1000 	}
   1001 
   1002 	stats->ps_recv = handlep->packets_read;
   1003 	stats->ps_ifdrop = 0;
   1004 	return 0;
   1005 }
   1006 
   1007 static int
   1008 usb_setdirection_linux(pcap_t *p, pcap_direction_t d)
   1009 {
   1010 	p->direction = d;
   1011 	return 0;
   1012 }
   1013 
   1014 
   1015 static int
   1016 usb_stats_linux_bin(pcap_t *handle, struct pcap_stat *stats)
   1017 {
   1018 	struct pcap_usb_linux *handlep = handle->priv;
   1019 	int ret;
   1020 	struct mon_bin_stats st;
   1021 	ret = ioctl(handle->fd, MON_IOCG_STATS, &st);
   1022 	if (ret < 0)
   1023 	{
   1024 		pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
   1025 		    errno, "Can't read stats from fd %d", handle->fd);
   1026 		return -1;
   1027 	}
   1028 
   1029 	stats->ps_recv = handlep->packets_read + st.queued;
   1030 	stats->ps_drop = st.dropped;
   1031 	stats->ps_ifdrop = 0;
   1032 	return 0;
   1033 }
   1034 
   1035 /*
   1036  * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
   1037  * <linux-kernel-source>/drivers/usb/mon/mon_bin.c binary ABI
   1038  */
   1039 static int
   1040 usb_read_linux_bin(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
   1041 {
   1042 	struct pcap_usb_linux *handlep = handle->priv;
   1043 	struct mon_bin_get info;
   1044 	int ret;
   1045 	struct pcap_pkthdr pkth;
   1046 	u_int clen = handle->snapshot - sizeof(pcap_usb_header);
   1047 
   1048 	/* the usb header is going to be part of 'packet' data*/
   1049 	info.hdr = (pcap_usb_header*) handle->buffer;
   1050 	info.data = (u_char *)handle->buffer + sizeof(pcap_usb_header);
   1051 	info.data_len = clen;
   1052 
   1053 	/* ignore interrupt system call errors */
   1054 	do {
   1055 		ret = ioctl(handle->fd, MON_IOCX_GET, &info);
   1056 		if (handle->break_loop)
   1057 		{
   1058 			handle->break_loop = 0;
   1059 			return -2;
   1060 		}
   1061 	} while ((ret == -1) && (errno == EINTR));
   1062 	if (ret < 0)
   1063 	{
   1064 		if (errno == EAGAIN)
   1065 			return 0;	/* no data there */
   1066 
   1067 		pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
   1068 		    errno, "Can't read from fd %d", handle->fd);
   1069 		return -1;
   1070 	}
   1071 
   1072 	/* we can get less that than really captured from kernel, depending on
   1073 	 * snaplen, so adjust header accordingly */
   1074 	if (info.hdr->data_len < clen)
   1075 		clen = info.hdr->data_len;
   1076 	info.hdr->data_len = clen;
   1077 	pkth.caplen = clen + sizeof(pcap_usb_header);
   1078 	pkth.len = info.hdr->data_len + sizeof(pcap_usb_header);
   1079 	pkth.ts.tv_sec = info.hdr->ts_sec;
   1080 	pkth.ts.tv_usec = info.hdr->ts_usec;
   1081 
   1082 	if (handle->fcode.bf_insns == NULL ||
   1083 	    bpf_filter(handle->fcode.bf_insns, handle->buffer,
   1084 	      pkth.len, pkth.caplen)) {
   1085 		handlep->packets_read++;
   1086 		callback(user, &pkth, handle->buffer);
   1087 		return 1;
   1088 	}
   1089 
   1090 	return 0;	/* didn't pass filter */
   1091 }
   1092 
   1093 /*
   1094  * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
   1095  * <linux-kernel-source>/drivers/usb/mon/mon_bin.c binary ABI
   1096  */
   1097 #define VEC_SIZE 32
   1098 static int
   1099 usb_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
   1100 {
   1101 	struct pcap_usb_linux *handlep = handle->priv;
   1102 	struct mon_bin_mfetch fetch;
   1103 	int32_t vec[VEC_SIZE];
   1104 	struct pcap_pkthdr pkth;
   1105 	pcap_usb_header* hdr;
   1106 	int nflush = 0;
   1107 	int packets = 0;
   1108 	u_int clen, max_clen;
   1109 
   1110 	max_clen = handle->snapshot - sizeof(pcap_usb_header);
   1111 
   1112 	for (;;) {
   1113 		int i, ret;
   1114 		int limit = max_packets - packets;
   1115 		if (limit <= 0)
   1116 			limit = VEC_SIZE;
   1117 		if (limit > VEC_SIZE)
   1118 			limit = VEC_SIZE;
   1119 
   1120 		/* try to fetch as many events as possible*/
   1121 		fetch.offvec = vec;
   1122 		fetch.nfetch = limit;
   1123 		fetch.nflush = nflush;
   1124 		/* ignore interrupt system call errors */
   1125 		do {
   1126 			ret = ioctl(handle->fd, MON_IOCX_MFETCH, &fetch);
   1127 			if (handle->break_loop)
   1128 			{
   1129 				handle->break_loop = 0;
   1130 				return -2;
   1131 			}
   1132 		} while ((ret == -1) && (errno == EINTR));
   1133 		if (ret < 0)
   1134 		{
   1135 			if (errno == EAGAIN)
   1136 				return 0;	/* no data there */
   1137 
   1138 			pcap_fmt_errmsg_for_errno(handle->errbuf,
   1139 			    PCAP_ERRBUF_SIZE, errno, "Can't mfetch fd %d",
   1140 			    handle->fd);
   1141 			return -1;
   1142 		}
   1143 
   1144 		/* keep track of processed events, we will flush them later */
   1145 		nflush = fetch.nfetch;
   1146 		for (i=0; i<fetch.nfetch; ++i) {
   1147 			/* discard filler */
   1148 			hdr = (pcap_usb_header*) &handlep->mmapbuf[vec[i]];
   1149 			if (hdr->event_type == '@')
   1150 				continue;
   1151 
   1152 			/* we can get less that than really captured from kernel, depending on
   1153 	 		* snaplen, so adjust header accordingly */
   1154 			clen = max_clen;
   1155 			if (hdr->data_len < clen)
   1156 				clen = hdr->data_len;
   1157 
   1158 			/* get packet info from header*/
   1159 			pkth.caplen = clen + sizeof(pcap_usb_header_mmapped);
   1160 			pkth.len = hdr->data_len + sizeof(pcap_usb_header_mmapped);
   1161 			pkth.ts.tv_sec = hdr->ts_sec;
   1162 			pkth.ts.tv_usec = hdr->ts_usec;
   1163 
   1164 			if (handle->fcode.bf_insns == NULL ||
   1165 			    bpf_filter(handle->fcode.bf_insns, (u_char*) hdr,
   1166 			      pkth.len, pkth.caplen)) {
   1167 				handlep->packets_read++;
   1168 				callback(user, &pkth, (u_char*) hdr);
   1169 				packets++;
   1170 			}
   1171 		}
   1172 
   1173 		/* with max_packets specifying "unlimited" we stop afer the first chunk*/
   1174 		if (PACKET_COUNT_IS_UNLIMITED(max_packets) || (packets == max_packets))
   1175 			break;
   1176 	}
   1177 
   1178 	/* flush pending events*/
   1179 	if (ioctl(handle->fd, MON_IOCH_MFLUSH, nflush) == -1) {
   1180 		pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
   1181 		    errno, "Can't mflush fd %d", handle->fd);
   1182 		return -1;
   1183 	}
   1184 	return packets;
   1185 }
   1186 
   1187 static void
   1188 usb_cleanup_linux_mmap(pcap_t* handle)
   1189 {
   1190 	struct pcap_usb_linux *handlep = handle->priv;
   1191 
   1192 	/* if we have a memory-mapped buffer, unmap it */
   1193 	if (handlep->mmapbuf != NULL) {
   1194 		munmap(handlep->mmapbuf, handlep->mmapbuflen);
   1195 		handlep->mmapbuf = NULL;
   1196 	}
   1197 	pcap_cleanup_live_common(handle);
   1198 }
   1199