The Tcpdump Group git mirrors - libpcap/blob - pcap-usb-linux.c

   1 /*
   2  * Copyright (c) 1999 - 2005 NetGroup, Politecnico di Torino (Italy)
   3  * Copyright (c) 2005 - 2006 CACE Technologies, Davis (California)
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  * notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  * notice, this list of conditions and the following disclaimer in the
  14  * documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the Politecnico di Torino, CACE Technologies
  16  * nor the names of its contributors may be used to endorse or promote
  17  * products derived from this software without specific prior written
  18  * permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  21  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  23  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  24  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  25  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  26  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  30  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * USB sniffing API implementation for Linux platform
  33  * By Paolo Abeni <paolo.abeni@email.it>
  34  *
  35  */
  36
  37 #ifdef HAVE_CONFIG_H
  38 #include "config.h"
  39 #endif
  40
  41 #include "pcap-int.h"
  42 #include "pcap-usb-linux.h"
  43 #include "pcap/usb.h"
  44
  45 #ifdef NEED_STRERROR_H
  46 #include "strerror.h"
  47 #endif
  48
  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
  60 #define USB_IFACE "usb"
  61 #define USB_DIR "/sys/kernel/debug/usbmon"
  62 #define USB_LINE_LEN 4096
  63
  64
  65 #define PIPE_IN                 0x80
  66 #define PIPE_ISOCHRONOUS        0
  67 #define PIPE_INTERRUPT          1
  68 #define PIPE_CONTROL            2
  69 #define PIPE_BULK               3
  70
  71 #if __BYTE_ORDER == __LITTLE_ENDIAN
  72 #define htols(s) s
  73 #define htoll(l) l
  74 #else
  75 #define htols(s) bswap_16(s)
  76 #define htoll(l) bswap_32(l)
  77 #endif
  78
  79 struct mon_bin_stats {
  80         u_int32_t queued;
  81         u_int32_t dropped;
  82 };
  83
  84 struct mon_bin_get {
  85         pcap_usb_header *hdr;
  86         void *data;
  87         size_t data_len;   /* Length of data (can be zero) */
  88 };
  89
  90 struct mon_bin_mfetch {
  91         int32_t *offvec;   /* Vector of events fetched */
  92         int32_t nfetch;    /* Number of events to fetch (out: fetched) */
  93         int32_t nflush;    /* Number of events to flush */
  94 };
  95
  96 #define MON_IOC_MAGIC 0x92
  97
  98 #define MON_IOCQ_URB_LEN _IO(MON_IOC_MAGIC, 1)
  99 #define MON_IOCX_URB  _IOWR(MON_IOC_MAGIC, 2, struct mon_bin_hdr)
 100 #define MON_IOCG_STATS _IOR(MON_IOC_MAGIC, 3, struct mon_bin_stats)
 101 #define MON_IOCT_RING_SIZE _IO(MON_IOC_MAGIC, 4)
 102 #define MON_IOCQ_RING_SIZE _IO(MON_IOC_MAGIC, 5)
 103 #define MON_IOCX_GET   _IOW(MON_IOC_MAGIC, 6, struct mon_bin_get)
 104 #define MON_IOCX_MFETCH _IOWR(MON_IOC_MAGIC, 7, struct mon_bin_mfetch)
 105 #define MON_IOCH_MFLUSH _IO(MON_IOC_MAGIC, 8)
 106
 107 #define MON_BIN_SETUP   0x1 /* setup hdr is present*/
 108 #define MON_BIN_SETUP_ZERO      0x2 /* setup buffer is not available */
 109 #define MON_BIN_DATA_ZERO       0x4 /* data buffer is not available */
 110 #define MON_BIN_ERROR   0x8
 111
 112 /* forward declaration */
 113 static int usb_stats_linux(pcap_t *, struct pcap_stat *);
 114 static int usb_stats_linux_bin(pcap_t *, struct pcap_stat *);
 115 static int usb_read_linux(pcap_t *, int , pcap_handler , u_char *);
 116 static int usb_read_linux_bin(pcap_t *, int , pcap_handler , u_char *);
 117 static int usb_read_linux_mmap(pcap_t *, int , pcap_handler , u_char *);
 118 static int usb_inject_linux(pcap_t *, const void *, size_t);
 119 static int usb_setfilter_linux(pcap_t *, struct bpf_program *);
 120 static int usb_setdirection_linux(pcap_t *, pcap_direction_t);
 121 static void usb_close_linux(pcap_t *);
 122 static void usb_close_linux_mmap(pcap_t *);
 123
 124 int
 125 usb_platform_finddevs(pcap_if_t **alldevsp, char *err_str)
 126 {
 127         pcap_if_t *devlist = *alldevsp;
 128         struct dirent* data;
 129         DIR* dir = opendir(USB_DIR);
 130         if (!dir) {
 131                 /* it's not fatal, but it would be useful to give a message
 132                    about debugfs:
 133                         modprobe usbmon
 134                         mount -t debugfs none_debugs /sys/kernel/debug
 135                  */
 136                 return 0;
 137         }
 138
 139         /* scan usbmon directory */
 140         int ret = 0;
 141         while ((data = readdir(dir)) != 0)
 142         {
 143                 char* name = data->d_name;
 144                 int len = strlen(name);
 145
 146                 if ((len >= 2) && name[len -1]== 't')
 147                 {
 148                         int n = name[0] - '0';
 149                         char dev_name[10], dev_descr[30];
 150                         snprintf(dev_name, 10, USB_IFACE"%d", n);
 151                         snprintf(dev_descr, 30, "USB bus number %d", n);
 152
 153                         if (pcap_add_if(&devlist, dev_name, 0,
 154                             dev_descr, err_str) < 0)
 155                         {
 156                                 ret = -1;
 157                                 break;
 158                         }
 159                 }
 160         }
 161         closedir(dir);
 162
 163         *alldevsp = devlist;
 164         return ret;
 165 }
 166
 167 static
 168 int usb_mmap(pcap_t* handle)
 169 {
 170         int len = ioctl(handle->fd, MON_IOCQ_RING_SIZE);
 171         if (len < 0)
 172                 return 0;
 173
 174         handle->buffer = mmap(0, len, PROT_READ, MAP_SHARED, handle->fd, 0);
 175         return handle->buffer != MAP_FAILED;
 176 }
 177
 178 pcap_t*
 179 usb_open_live(const char* bus, int snaplen, int promisc , int to_ms, char* errmsg)
 180 {
 181         char            full_path[USB_LINE_LEN];
 182         pcap_t          *handle;
 183
 184         /* Allocate a handle for this session. */
 185         handle = malloc(sizeof(*handle));
 186         if (handle == NULL) {
 187                 snprintf(errmsg, PCAP_ERRBUF_SIZE, "malloc: %s",
 188                         pcap_strerror(errno));
 189                 return NULL;
 190         }
 191
 192         /* Initialize some components of the pcap structure. */
 193         memset(handle, 0, sizeof(*handle));
 194         handle->snapshot        = snaplen;
 195         handle->md.timeout      = to_ms;
 196         handle->bufsize = snaplen;
 197         handle->offset = 0;
 198         handle->linktype = DLT_USB;
 199
 200         /*
 201          * "handle->fd" is a real file , so "select()" and "poll()"
 202          * work on it.
 203          */
 204         handle->selectable_fd = handle->fd;
 205
 206         handle->inject_op = usb_inject_linux;
 207         handle->setfilter_op = usb_setfilter_linux;
 208         handle->setdirection_op = usb_setdirection_linux;
 209         handle->set_datalink_op = NULL; /* can't change data link type */
 210         handle->getnonblock_op = pcap_getnonblock_fd;
 211         handle->setnonblock_op = pcap_setnonblock_fd;
 212         handle->close_op = usb_close_linux;
 213
 214         /*get usb bus index from device name */
 215         if (sscanf(bus, USB_IFACE"%d", &handle->md.ifindex) != 1)
 216         {
 217                 snprintf(errmsg, PCAP_ERRBUF_SIZE,
 218                         "Can't get USB bus index from %s", bus);
 219                 free(handle);
 220                 return NULL;
 221         }
 222
 223         /*now select the read method: try to open binary interface */
 224         snprintf(full_path, USB_LINE_LEN, LINUX_USB_MON_DEV"%d", handle->md.ifindex);
 225         handle->fd = open(full_path, O_RDONLY, 0);
 226         if (handle->fd >= 0)
 227         {
 228                 /* binary api is available, try to use fast mmap access */
 229                 if (usb_mmap(handle)) {
 230                         handle->stats_op = usb_stats_linux_bin;
 231                         handle->read_op = usb_read_linux_mmap;
 232                         handle->close_op = usb_close_linux_mmap;
 233                         return handle;
 234                 }
 235
 236                 /* can't mmap, use plain binary interface access */
 237                 handle->stats_op = usb_stats_linux_bin;
 238                 handle->read_op = usb_read_linux_bin;
 239         }
 240         else {
 241                 /*Binary interface not available, try open text interface */
 242                 snprintf(full_path, USB_LINE_LEN, USB_DIR"/%dt", handle->md.ifindex);
 243                 handle->fd = open(full_path, O_RDONLY, 0);
 244                 if (handle->fd < 0)
 245                 {
 246                         /* no more fallback, give it up*/
 247                         snprintf(errmsg, PCAP_ERRBUF_SIZE,
 248                                 "Can't open USB bus file %s: %s", full_path, strerror(errno));
 249                         free(handle);
 250                         return NULL;
 251                 }
 252                 handle->stats_op = usb_stats_linux;
 253                 handle->read_op = usb_read_linux;
 254         }
 255
 256         /* for plain binary access and text access we need to allocate the read
 257          * buffer */
 258         handle->buffer = malloc(handle->bufsize);
 259         if (!handle->buffer) {
 260                 snprintf(errmsg, PCAP_ERRBUF_SIZE,
 261                          "malloc: %s", pcap_strerror(errno));
 262                 usb_close_linux(handle);
 263                 return NULL;
 264         }
 265         return handle;
 266 }
 267
 268 static inline int
 269 ascii_to_int(char c)
 270 {
 271         return c < 'A' ? c- '0': ((c<'a') ? c - 'A' + 10: c-'a'+10);
 272 }
 273
 274 /*
 275  * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
 276  * <linux-kernel-source>/drivers/usb/mon/mon_text.c for urb string
 277  * format description
 278  */
 279 static int
 280 usb_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
 281 {
 282         /* see:
 283         * /usr/src/linux/Documentation/usb/usbmon.txt
 284         * for message format
 285         */
 286         unsigned timestamp;
 287         int tag, cnt, ep_num, dev_addr, dummy, ret;
 288         char etype, pipeid1, pipeid2, status[16], urb_tag, line[USB_LINE_LEN];
 289         char *string = line;
 290         u_char * rawdata = handle->buffer;
 291         struct pcap_pkthdr pkth;
 292         pcap_usb_header* uhdr = (pcap_usb_header*)handle->buffer;
 293         u_char urb_transfer=0;
 294         int incoming=0;
 295
 296         /* ignore interrupt system call errors */
 297         do {
 298                 ret = read(handle->fd, line, USB_LINE_LEN - 1);
 299                 if (handle->break_loop)
 300                 {
 301                         handle->break_loop = 0;
 302                         return -2;
 303                 }
 304         } while ((ret == -1) && (errno == EINTR));
 305         if (ret < 0)
 306         {
 307                 if (errno == EAGAIN)
 308                         return 0;       /* no data there */
 309
 310                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 311                     "Can't read from fd %d: %s", handle->fd, strerror(errno));
 312                 return -1;
 313         }
 314
 315         /* read urb header; %n argument may increment return value, but it's
 316         * not mandatory, so does not count on it*/
 317         string[ret] = 0;
 318         ret = sscanf(string, "%x %d %c %c%c:%d:%d %s%n", &tag, &timestamp, &etype,
 319                 &pipeid1, &pipeid2, &dev_addr, &ep_num, status,
 320                 &cnt);
 321         if (ret < 8)
 322         {
 323                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 324                     "Can't parse USB bus message '%s', too few tokens (expected 8 got %d)",
 325                     string, ret);
 326                 return -1;
 327         }
 328         uhdr->id = tag;
 329         uhdr->endpoint_number = ep_num;
 330         uhdr->device_address = dev_addr;
 331         uhdr->bus_id = htols(handle->md.ifindex);
 332         uhdr->status = 0;
 333         string += cnt;
 334
 335         /* don't use usbmon provided timestamp, since it have low precision*/
 336         if (gettimeofday(&pkth.ts, NULL) < 0)
 337         {
 338                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 339                         "Can't get timestamp for message '%s' %d:%s",
 340                         string, errno, strerror(errno));
 341                 return -1;
 342         }
 343         uhdr->ts_sec = pkth.ts.tv_sec;
 344         uhdr->ts_usec = pkth.ts.tv_usec;
 345
 346         /* parse endpoint information */
 347         if (pipeid1 == 'C')
 348                 urb_transfer = URB_CONTROL;
 349         else if (pipeid1 == 'Z')
 350                 urb_transfer = URB_ISOCHRONOUS;
 351         else if (pipeid1 == 'I')
 352                 urb_transfer = URB_INTERRUPT;
 353         else if (pipeid1 == 'B')
 354                 urb_transfer = URB_BULK;
 355         if (pipeid2 == 'i') {
 356                 urb_transfer |= URB_TRANSFER_IN;
 357                 incoming = 1;
 358         }
 359         if (etype == 'C')
 360                 incoming = !incoming;
 361
 362         /* direction check*/
 363         if (incoming)
 364         {
 365                 if (handle->direction == PCAP_D_OUT)
 366                         return 0;
 367         }
 368         else
 369                 if (handle->direction == PCAP_D_IN)
 370                         return 0;
 371         uhdr->event_type = etype;
 372         uhdr->transfer_type = urb_transfer;
 373         pkth.caplen = sizeof(pcap_usb_header);
 374         rawdata += sizeof(pcap_usb_header);
 375
 376         /* check if this is a setup packet */
 377         ret = sscanf(status, "%d", &dummy);
 378         if (ret != 1)
 379         {
 380                 /* this a setup packet, setup data can be filled with underscore if
 381                 * usbmon has not been able to read them, so we must parse this fields as
 382                 * strings */
 383                 pcap_usb_setup* shdr;
 384                 char str1[3], str2[3], str3[5], str4[5], str5[5];
 385                 ret = sscanf(string, "%s %s %s %s %s%n", str1, str2, str3, str4,
 386                 str5, &cnt);
 387                 if (ret < 5)
 388                 {
 389                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 390                                 "Can't parse USB bus message '%s', too few tokens (expected 5 got %d)",
 391                                 string, ret);
 392                         return -1;
 393                 }
 394                 string += cnt;
 395
 396                 /* try to convert to corresponding integer */
 397                 shdr = &uhdr->setup;
 398                 shdr->bmRequestType = strtoul(str1, 0, 16);
 399                 shdr->bRequest = strtoul(str2, 0, 16);
 400                 shdr->wValue = htols(strtoul(str3, 0, 16));
 401                 shdr->wIndex = htols(strtoul(str4, 0, 16));
 402                 shdr->wLength = htols(strtoul(str5, 0, 16));
 403
 404                 uhdr->setup_flag = 0;
 405         }
 406         else
 407                 uhdr->setup_flag = 1;
 408
 409         /* read urb data */
 410         ret = sscanf(string, " %d%n", &uhdr->urb_len, &cnt);
 411         if (ret < 1)
 412         {
 413                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 414                   "Can't parse urb length from '%s'", string);
 415                 return -1;
 416         }
 417         string += cnt;
 418
 419         /* urb tag is not present if urb length is 0, so we can stop here
 420          * text parsing */
 421         pkth.len = uhdr->urb_len+pkth.caplen;
 422         uhdr->data_flag = 1;
 423         uhdr->data_len = 0;
 424         if (uhdr->urb_len == pkth.caplen)
 425                 goto got;
 426
 427         /* check for data presence; data is present if and only if urb tag is '=' */
 428         if (sscanf(string, " %c", &urb_tag) != 1)
 429         {
 430                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 431                         "Can't parse urb tag from '%s'", string);
 432                 return -1;
 433         }
 434
 435         if (urb_tag != '=')
 436                 goto got;
 437
 438         /* skip urb tag and following space */
 439         string += 3;
 440
 441         /* if we reach this point we got some urb data*/
 442         uhdr->data_flag = 0;
 443
 444         /* read all urb data; if urb length is greater then the usbmon internal
 445          * buffer length used by the kernel to spool the URB, we get only
 446          * a partial information.
 447          * At least until linux 2.6.17 there is no way to set usbmon intenal buffer
 448          * length and default value is 130. */
 449         while ((string[0] != 0) && (string[1] != 0) && (pkth.caplen < handle->snapshot))
 450         {
 451                 rawdata[0] = ascii_to_int(string[0]) * 16 + ascii_to_int(string[1]);
 452                 rawdata++;
 453                 string+=2;
 454                 if (string[0] == ' ')
 455                         string++;
 456                 pkth.caplen++;
 457                 uhdr->data_len++;
 458         }
 459
 460 got:
 461         handle->md.packets_read++;
 462         if (pkth.caplen > handle->snapshot)
 463                 pkth.caplen = handle->snapshot;
 464
 465         callback(user, &pkth, handle->buffer);
 466         return 1;
 467 }
 468
 469 static int
 470 usb_inject_linux(pcap_t *handle, const void *buf, size_t size)
 471 {
 472         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on "
 473                 "USB devices");
 474         return (-1);
 475 }
 476
 477 static void
 478 usb_close_linux(pcap_t* handle)
 479 {
 480         /* handle fill be freed in pcap_close() 'common' code */
 481         close(handle->fd);
 482         if (handle->buffer)
 483                 free(handle->buffer);
 484 }
 485
 486 static int
 487 usb_stats_linux(pcap_t *handle, struct pcap_stat *stats)
 488 {
 489         int dummy, ret, consumed, cnt;
 490         char string[USB_LINE_LEN];
 491         char token[USB_LINE_LEN];
 492         char * ptr = string;
 493         snprintf(string, USB_LINE_LEN, USB_DIR"/%ds", handle->md.ifindex);
 494
 495         int fd = open(string, O_RDONLY, 0);
 496         if (fd < 0)
 497         {
 498                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 499                         "Can't open USB stats file %s: %s",
 500                         string, strerror(errno));
 501                 return -1;
 502         }
 503
 504         /* read stats line */
 505         do {
 506                 ret = read(fd, string, USB_LINE_LEN-1);
 507         } while ((ret == -1) && (errno == EINTR));
 508         close(fd);
 509
 510         if (ret < 0)
 511         {
 512                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 513                         "Can't read stats from fd %d ", fd);
 514                 return -1;
 515         }
 516         string[ret] = 0;
 517
 518         /* extract info on dropped urbs */
 519         for (consumed=0; consumed < ret; ) {
 520                 int ntok = sscanf(ptr, "%s%n", token, &cnt);
 521                 if (ntok != 2)
 522                         break;
 523                 consumed += cnt;
 524                 ptr += cnt;
 525                 if (strcmp(token, "nreaders") == 0)
 526                         ret = sscanf(ptr, "%d", &stats->ps_drop);
 527                 else
 528                         ret = sscanf(ptr, "%d", &dummy);
 529                 if (ntok != 2)
 530                         break;
 531                 consumed += cnt;
 532                 ptr += cnt;
 533         }
 534
 535         stats->ps_recv = handle->md.packets_read;
 536         stats->ps_ifdrop = 0;
 537         return 0;
 538 }
 539
 540 static int
 541 usb_setfilter_linux(pcap_t *p, struct bpf_program *fp)
 542 {
 543         return 0;
 544 }
 545
 546 static int
 547 usb_setdirection_linux(pcap_t *p, pcap_direction_t d)
 548 {
 549         p->direction = d;
 550         return 0;
 551 }
 552
 553
 554 static int
 555 usb_stats_linux_bin(pcap_t *handle, struct pcap_stat *stats)
 556 {
 557         int dummy, ret;
 558         struct mon_bin_stats st;
 559         ret = ioctl(handle->fd, MON_IOCG_STATS, &st);
 560         if (ret < 0)
 561         {
 562                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 563                         "Can't read stats from fd %d:%s ", handle->fd, strerror(errno));
 564                 return -1;
 565         }
 566
 567         stats->ps_recv = handle->md.packets_read + st.queued;
 568         stats->ps_ifdrop = st.dropped;
 569         return 0;
 570 }
 571
 572 /*
 573  * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
 574  * <linux-kernel-source>/drivers/usb/mon/mon_bin.c binary ABI
 575  */
 576 static int
 577 usb_read_linux_bin(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
 578 {
 579         struct mon_bin_get info;
 580         int ret;
 581         struct pcap_pkthdr pkth;
 582         int hdr_size;
 583         u_short flags = 0;
 584         int clen = handle->snapshot - sizeof(pcap_usb_header);
 585
 586         /* the usb header is going to be part of 'packet' data*/
 587         info.hdr = (pcap_usb_header*) handle->buffer;
 588         info.data = handle->buffer + sizeof(pcap_usb_header);
 589         info.data_len = clen;
 590         /* ignore interrupt system call errors */
 591         do {
 592                 ret = ioctl(handle->fd, MON_IOCX_GET, &info);
 593                 if (handle->break_loop)
 594                 {
 595                         handle->break_loop = 0;
 596                         return -2;
 597                 }
 598         } while ((ret == -1) && (errno == EINTR));
 599         if (ret < 0)
 600         {
 601                 if (errno == EAGAIN)
 602                         return 0;       /* no data there */
 603
 604                 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 605                     "Can't read from fd %d: %s", handle->fd, strerror(errno));
 606                 return -1;
 607         }
 608
 609         /* we can get less that than really captured from kernel, depending on
 610          * snaplen, so adjust header accordingly */
 611         if (info.hdr->data_len < clen)
 612                 clen = info.hdr->data_len;
 613         info.hdr->data_len = clen;
 614         pkth.caplen = clen + sizeof(pcap_usb_header);
 615         pkth.len = info.hdr->urb_len + sizeof(pcap_usb_header);
 616         pkth.ts.tv_sec = info.hdr->ts_sec;
 617         pkth.ts.tv_usec = info.hdr->ts_usec;
 618
 619         handle->md.packets_read++;
 620         callback(user, &pkth, handle->buffer);
 621         return 1;
 622 }
 623
 624 /*
 625  * see <linux-kernel-source>/Documentation/usb/usbmon.txt and
 626  * <linux-kernel-source>/drivers/usb/mon/mon_bin.c binary ABI
 627  */
 628 #define VEC_SIZE 32
 629 static int
 630 usb_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
 631 {
 632         struct mon_bin_mfetch fetch;
 633         uint32_t vec[VEC_SIZE];
 634         struct pcap_pkthdr pkth;
 635         pcap_usb_header* hdr;
 636         int nflush = 0;
 637         int packets = 0;
 638
 639         for (;;) {
 640                 int i, ret;
 641                 int limit = max_packets - packets;
 642                 if (limit < 0)
 643                         limit = VEC_SIZE;
 644                 if (limit > VEC_SIZE)
 645                         limit = VEC_SIZE;
 646
 647                 /* try to fetch as many events as possible*/
 648                 fetch.offvec = vec;
 649                 fetch.nfetch = limit;
 650                 fetch.nflush = nflush;
 651                 /* ignore interrupt system call errors */
 652                 do {
 653                         ret = ioctl(handle->fd, MON_IOCX_MFETCH, &fetch);
 654                         if (handle->break_loop)
 655                         {
 656                                 handle->break_loop = 0;
 657                                 return -2;
 658                         }
 659                 } while ((ret == -1) && (errno == EINTR));
 660                 if (ret < 0)
 661                 {
 662                         if (errno == EAGAIN)
 663                                 return 0;       /* no data there */
 664
 665                         snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
 666                             "Can't mfetch fd %d: %s", handle->fd, strerror(errno));
 667                         return -1;
 668                 }
 669
 670                 /* keep track of processed events, we will flush them later */
 671                 nflush = fetch.nfetch;
 672                 for (i=0; i<fetch.nfetch; ++i) {
 673                         /* discard filler */
 674                         hdr = (pcap_usb_header*) &handle->buffer[vec[i]];
 675                         if (hdr->event_type == '@')
 676                                 continue;
 677
 678                         /* get packet info from header*/
 679                         pkth.caplen = hdr->data_len + sizeof(pcap_usb_header);
 680                         pkth.len = hdr->urb_len + sizeof(pcap_usb_header);
 681                         pkth.ts.tv_sec = hdr->ts_sec;
 682                         pkth.ts.tv_usec = hdr->ts_usec;
 683
 684                         handle->md.packets_read++;
 685                         callback(user, &pkth, (u_char*) hdr);
 686                         packets++;
 687                 }
 688
 689                 /* with max_packets == -1 we stop afer the first chunk*/
 690                 if ((max_packets == -1) || (packets == max_packets))
 691                         break;
 692         }
 693
 694         /* flush pending events*/
 695         ioctl(handle->fd, MON_IOCH_MFLUSH, nflush);
 696         return packets;
 697 }
 698
 699 static void
 700 usb_close_linux_mmap(pcap_t* handle)
 701 {
 702         /* handle fill be freed in pcap_close() 'common' code, buffer must not
 703          * be freed because it's memory mapped */
 704         close(handle->fd);
 705 }