/* * 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 * Modifications: Kris Katterjohn * */ #ifdef HAVE_CONFIG_H #include #endif #include "pcap-int.h" #include "pcap-usb-linux.h" #include "pcap/usb.h" #include "extract.h" #ifdef NEED_STRERROR_H #include "strerror.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #ifdef HAVE_LINUX_USBDEVICE_FS_H /* * We might need to define __user for * . */ #ifdef HAVE_LINUX_COMPILER_H #include #endif /* HAVE_LINUX_COMPILER_H */ #include #endif /* HAVE_LINUX_USBDEVICE_FS_H */ #define USB_IFACE "usbmon" #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_bin(pcap_t *, struct pcap_stat *); 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 *, int); static int usb_setdirection_linux(pcap_t *, pcap_direction_t); static void usb_cleanup_linux_mmap(pcap_t *); /* 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]; snprintf(dev_name, 10, USB_IFACE"%d", n); /* * XXX - is there any notion of "up" and "running"? */ if (n == 0) { /* * As this refers to all buses, there's no notion of * "connected" vs. "disconnected", as that's a property * that would apply to a particular USB interface. */ if (add_dev(devlistp, dev_name, PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "Raw USB traffic, all USB buses", err_str) == NULL) return -1; } else { /* * XXX - is there a way to determine whether anything's * plugged into this bus interface or not, and set * PCAP_IF_CONNECTION_STATUS_CONNECTED or * PCAP_IF_CONNECTION_STATUS_DISCONNECTED? */ snprintf(dev_descr, 30, "Raw USB traffic, bus number %d", n); if (add_dev(devlistp, dev_name, 0, dev_descr, err_str) == NULL) return -1; } return 0; } int usb_findalldevs(pcap_if_list_t *devlistp, char *err_str) { char usb_mon_dir[PATH_MAX]; char *usb_mon_prefix; size_t usb_mon_prefix_len; struct dirent* data; int ret = 0; DIR* dir; int n; char* name; /* * We require 2.6.27 or later kernels, so we have binary-mode support. * What do the device names look like? * Split LINUX_USB_MON_DEV into a directory that we'll * scan and a file name prefix that we'll check for. */ pcap_strlcpy(usb_mon_dir, LINUX_USB_MON_DEV, sizeof usb_mon_dir); usb_mon_prefix = strrchr(usb_mon_dir, '/'); if (usb_mon_prefix == NULL) { /* * This "shouldn't happen". Just give up if it * does. */ return 0; } *usb_mon_prefix++ = '\0'; usb_mon_prefix_len = strlen(usb_mon_prefix); /* * Open the directory and scan it. */ dir = opendir(usb_mon_dir); if (dir != NULL) { while ((ret == 0) && ((data = readdir(dir)) != 0)) { name = data->d_name; /* * Is this a usbmon device? */ if (strncmp(name, usb_mon_prefix, usb_mon_prefix_len) != 0) continue; /* no */ /* * What's the device number? */ if (sscanf(&name[usb_mon_prefix_len], "%d", &n) == 0) continue; /* failed */ ret = usb_dev_add(devlistp, n, err_str); } closedir(dir); } return 0; } /* * Matches what's in mon_bin.c in the Linux kernel. */ #define MIN_RING_SIZE (8*1024) #define MAX_RING_SIZE (1200*1024) static int usb_set_ring_size(pcap_t* handle, int header_size) { /* * A packet from binary usbmon has: * * 1) a fixed-length header, of size header_size; * 2) descriptors, for isochronous transfers; * 3) the payload. * * The kernel buffer has a size, defaulting to 300KB, with a * minimum of 8KB and a maximum of 1200KB. The size is set with * the MON_IOCT_RING_SIZE ioctl; the size passed in is rounded up * to a page size. * * No more than {buffer size}/5 bytes worth of payload is saved. * Therefore, if we subtract the fixed-length size from the * snapshot length, we have the biggest payload we want (we * don't worry about the descriptors - if we have descriptors, * we'll just discard the last bit of the payload to get it * to fit). We multiply that result by 5 and set the buffer * size to that value. */ int ring_size; if (handle->snapshot < header_size) handle->snapshot = header_size; /* The maximum snapshot size is small enough that this won't overflow */ ring_size = (handle->snapshot - header_size) * 5; /* * Will this get an error? * (There's no wqy to query the minimum or maximum, so we just * copy the value from the kernel source. We don't round it * up to a multiple of the page size.) */ if (ring_size > MAX_RING_SIZE) { /* * Yes. Lower the ring size to the maximum, and set the * snapshot length to the value that would give us a * maximum-size ring. */ ring_size = MAX_RING_SIZE; handle->snapshot = header_size + (MAX_RING_SIZE/5); } else if (ring_size < MIN_RING_SIZE) { /* * Yes. Raise the ring size to the minimum, but leave * the snapshot length unchanged, so we show the * callback no more data than specified by the * snapshot length. */ ring_size = MIN_RING_SIZE; } if (ioctl(handle->fd, MON_IOCT_RING_SIZE, ring_size) == -1) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "Can't set ring size from fd %d", handle->fd); return -1; } return ring_size; } static int usb_mmap(pcap_t* handle) { struct pcap_usb_linux *handlep = handle->priv; int len; /* * Attempt to set the ring size as appropriate for the snapshot * length, reducing the snapshot length if that'd make the ring * bigger than the kernel supports. */ len = usb_set_ring_size(handle, (int)sizeof(pcap_usb_header_mmapped)); if (len == -1) { /* Failed. Fall back on non-memory-mapped access. */ return 0; } handlep->mmapbuflen = len; handlep->mmapbuf = mmap(0, handlep->mmapbuflen, PROT_READ, MAP_SHARED, handle->fd, 0); if (handlep->mmapbuf == MAP_FAILED) { /* * Failed. We don't treat that as a fatal error, we * just try to fall back on non-memory-mapped access. */ return 0; } return 1; } #ifdef HAVE_LINUX_USBDEVICE_FS_H #define CTRL_TIMEOUT (5*1000) /* milliseconds */ #define USB_DIR_IN 0x80 #define USB_TYPE_STANDARD 0x00 #define USB_RECIP_DEVICE 0x00 #define USB_REQ_GET_DESCRIPTOR 6 #define USB_DT_DEVICE 1 #define USB_DT_CONFIG 2 #define USB_DEVICE_DESCRIPTOR_SIZE 18 #define USB_CONFIG_DESCRIPTOR_SIZE 9 /* 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 busdevpath[sizeof("/dev/bus/usb/000/") + NAME_MAX]; DIR* dir; uint8_t descriptor[USB_DEVICE_DESCRIPTOR_SIZE]; uint8_t configdesc[USB_CONFIG_DESCRIPTOR_SIZE]; /* scan usb bus directories for device nodes */ snprintf(busdevpath, sizeof(busdevpath), "/dev/bus/usb/%03d", bus); dir = opendir(busdevpath); if (!dir) return; while ((ret >= 0) && ((data = readdir(dir)) != 0)) { int fd; char* name = data->d_name; if (name[0] == '.') continue; snprintf(busdevpath, sizeof(busdevpath), "/dev/bus/usb/%03d/%s", bus, data->d_name); fd = open(busdevpath, 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(descriptor); #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(descriptor); #endif ctrl.data = descriptor; ctrl.timeout = CTRL_TIMEOUT; ret = ioctl(fd, USBDEVFS_CONTROL, &ctrl); /* Request CONFIGURATION descriptor alone to know wTotalLength */ #ifdef HAVE_STRUCT_USBDEVFS_CTRLTRANSFER_BREQUESTTYPE ctrl.wValue = USB_DT_CONFIG << 8; ctrl.wLength = sizeof(configdesc); #else ctrl.value = USB_DT_CONFIG << 8; ctrl.length = sizeof(configdesc); #endif ctrl.data = configdesc; ret = ioctl(fd, USBDEVFS_CONTROL, &ctrl); if (ret >= 0) { uint16_t wtotallength; wtotallength = EXTRACT_LE_U_2(&configdesc[2]); #ifdef HAVE_STRUCT_USBDEVFS_CTRLTRANSFER_BREQUESTTYPE ctrl.wLength = wtotallength; #else ctrl.length = wtotallength; #endif ctrl.data = malloc(wtotallength); if (ctrl.data) { ret = ioctl(fd, USBDEVFS_CONTROL, &ctrl); free(ctrl.data); } } 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, 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) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get USB bus index from %s", handle->opt.device); return PCAP_ERROR; } /* * We require 2.6.27 or later kernels, so we have binary-mode support. * Try to open the binary interface. */ snprintf(full_path, USB_LINE_LEN, LINUX_USB_MON_DEV"%d", handlep->bus_index); handle->fd = open(full_path, O_RDONLY, 0); if (handle->fd < 0) { /* * The attempt failed; why? */ switch (errno) { case ENOENT: /* * The device doesn't exist. * That could either mean that there's * no support for monitoring USB buses * (which probably means "the usbmon * module isn't loaded") or that there * is but that *particular* device * doesn't exist (no "scan all buses" * device if the bus index is 0, no * such bus if the bus index isn't 0). */ return PCAP_ERROR_NO_SUCH_DEVICE; case EACCES: /* * We didn't have permission to open it. */ return PCAP_ERROR_PERM_DENIED; default: /* * Something went wrong. */ pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "Can't open USB bus file %s", full_path); return PCAP_ERROR; } } if (handle->opt.rfmon) { /* * Monitor mode doesn't apply to USB devices. */ close(handle->fd); return PCAP_ERROR_RFMON_NOTSUP; } /* try to use fast mmap access */ if (usb_mmap(handle)) { /* We succeeded. */ handle->linktype = DLT_USB_LINUX_MMAPPED; handle->stats_op = usb_stats_linux_bin; handle->read_op = usb_read_linux_mmap; handle->cleanup_op = usb_cleanup_linux_mmap; #ifdef HAVE_LINUX_USBDEVICE_FS_H probe_devices(handlep->bus_index); #endif /* * "handle->fd" is a real file, so * "select()" and "poll()" work on it. */ handle->selectable_fd = handle->fd; return 0; } /* * We failed; try plain binary interface access. * * Attempt to set the ring size as appropriate for * the snapshot length, reducing the snapshot length * if that'd make the ring bigger than the kernel * supports. */ if (usb_set_ring_size(handle, (int)sizeof(pcap_usb_header)) == -1) { /* Failed. */ close(handle->fd); return PCAP_ERROR; } handle->stats_op = usb_stats_linux_bin; handle->read_op = usb_read_linux_bin; #ifdef HAVE_LINUX_USBDEVICE_FS_H probe_devices(handlep->bus_index); #endif /* * "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 int usb_inject_linux(pcap_t *handle, const void *buf _U_, int size _U_) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Packet injection is not supported on USB devices"); return (-1); } static int usb_setdirection_linux(pcap_t *p, pcap_direction_t d) { /* * It's guaranteed, at this point, that d is a valid * direction value. */ 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 /Documentation/usb/usbmon.txt and * /drivers/usb/mon/mon_bin.c binary ABI */ static int usb_read_linux_bin(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user) { struct pcap_usb_linux *handlep = handle->priv; struct mon_bin_get info; int ret; struct pcap_pkthdr pkth; u_int clen = handle->snapshot - sizeof(pcap_usb_header); /* the usb header is going to be part of 'packet' data*/ info.hdr = (pcap_usb_header*) handle->buffer; info.data = (u_char *)handle->buffer + sizeof(pcap_usb_header); info.data_len = clen; /* ignore interrupt system call errors */ do { ret = ioctl(handle->fd, MON_IOCX_GET, &info); if (handle->break_loop) { handle->break_loop = 0; return -2; } } while ((ret == -1) && (errno == EINTR)); if (ret < 0) { if (errno == EAGAIN) return 0; /* no data there */ pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "Can't read from fd %d", handle->fd); return -1; } /* * info.hdr->data_len is the number of bytes of isochronous * descriptors (if any) plus the number of bytes of data * provided. There are no isochronous descriptors here, * because we're using the old 48-byte header. * * If info.hdr->data_flag is non-zero, there's no URB data; * info.hdr->urb_len is the size of the buffer into which * data is to be placed; it does not represent the amount * of data transferred. If info.hdr->data_flag is zero, * there is URB data, and info.hdr->urb_len is the number * of bytes transmitted or received; it doesn't include * isochronous descriptors. * * The kernel may give us more data than the snaplen; if it did, * reduce the data length so that the total number of bytes we * tell our client we have is not greater than the snaplen. */ if (info.hdr->data_len < clen) clen = info.hdr->data_len; info.hdr->data_len = clen; pkth.caplen = sizeof(pcap_usb_header) + clen; if (info.hdr->data_flag) { /* * No data; just base the on-the-wire length on * info.hdr->data_len (so that it's >= the captured * length). */ pkth.len = sizeof(pcap_usb_header) + info.hdr->data_len; } else { /* * We got data; base the on-the-wire length on * info.hdr->urb_len, so that it includes data * discarded by the USB monitor device due to * its buffer being too small. */ pkth.len = sizeof(pcap_usb_header) + info.hdr->urb_len; } pkth.ts.tv_sec = (time_t)info.hdr->ts_sec; pkth.ts.tv_usec = info.hdr->ts_usec; if (handle->fcode.bf_insns == NULL || pcap_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 /Documentation/usb/usbmon.txt and * /drivers/usb/mon/mon_bin.c binary ABI */ #define VEC_SIZE 32 static int usb_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) { struct pcap_usb_linux *handlep = handle->priv; struct mon_bin_mfetch fetch; int32_t vec[VEC_SIZE]; struct pcap_pkthdr pkth; pcap_usb_header_mmapped* hdr; int nflush = 0; int packets = 0; u_int clen, max_clen; max_clen = handle->snapshot - sizeof(pcap_usb_header_mmapped); for (;;) { int i, ret; int limit = max_packets - packets; if (limit <= 0) limit = VEC_SIZE; if (limit > VEC_SIZE) limit = VEC_SIZE; /* try to fetch as many events as possible*/ fetch.offvec = vec; fetch.nfetch = limit; fetch.nflush = nflush; /* ignore interrupt system call errors */ do { ret = ioctl(handle->fd, MON_IOCX_MFETCH, &fetch); if (handle->break_loop) { handle->break_loop = 0; return -2; } } while ((ret == -1) && (errno == EINTR)); if (ret < 0) { if (errno == EAGAIN) return 0; /* no data there */ pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "Can't mfetch fd %d", handle->fd); return -1; } /* keep track of processed events, we will flush them later */ nflush = fetch.nfetch; for (i=0; immapbuf[vec[i]]; if (hdr->event_type == '@') continue; /* * hdr->data_len is the number of bytes of * isochronous descriptors (if any) plus the * number of bytes of data provided. * * If hdr->data_flag is non-zero, there's no * URB data; hdr->urb_len is the size of the * buffer into which data is to be placed; it does * not represent the amount of data transferred. * If hdr->data_flag is zero, there is URB data, * and hdr->urb_len is the number of bytes * transmitted or received; it doesn't include * isochronous descriptors. * * The kernel may give us more data than the * snaplen; if it did, reduce the data length * so that the total number of bytes we * tell our client we have is not greater than * the snaplen. */ clen = max_clen; if (hdr->data_len < clen) clen = hdr->data_len; pkth.caplen = sizeof(pcap_usb_header_mmapped) + clen; if (hdr->data_flag) { /* * No data; just base the on-the-wire length * on hdr->data_len (so that it's >= the * captured length). */ pkth.len = sizeof(pcap_usb_header_mmapped) + hdr->data_len; } else { /* * We got data; base the on-the-wire length * on hdr->urb_len, so that it includes * data discarded by the USB monitor device * due to its buffer being too small. */ pkth.len = sizeof(pcap_usb_header_mmapped) + (hdr->ndesc * sizeof (usb_isodesc)) + hdr->urb_len; } pkth.ts.tv_sec = (time_t)hdr->ts_sec; pkth.ts.tv_usec = hdr->ts_usec; if (handle->fcode.bf_insns == NULL || pcap_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 after 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); }