1 files changed, 251 insertions, 0 deletions

diff --git a/src/transport/wlan/radiotap-parser.c b/src/transport/wlan/radiotap-parser.c
new file mode 100644
index 000000000..46ea6d542
--- /dev/null
+++ b/src/transport/wlan/radiotap-parser.c
@@ -0,0 +1,251 @@
+ /*
+  *  Copyright (c) 2007, 2008, Andy Green <andy@warmcat.com>
+  *
+  *  This program is free software; you can redistribute it and/or modify
+  *  it under the terms of the GNU General Public License as published by
+  *  the Free Software Foundation; either version 2 of the License, or
+  *  (at your option) any later version.
+  *
+  *  This program is distributed in the hope that it will be useful,
+  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  *  GNU General Public License for more details.
+  *
+  *  You should have received a copy of the GNU General Public License
+  *  along with this program; if not, write to the Free Software
+  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+  */
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <errno.h>
+
+#include "radiotap-parser.h"
+
+
+/*
+ * Radiotap header iteration
+ *   implemented in src/radiotap-parser.c
+ *
+ * call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator
+ * struct ieee80211_radiotap_iterator (no need to init the struct beforehand)
+ * then loop calling __ieee80211_radiotap_iterator_next()... it returns -1
+ * if there are no more args in the header, or the next argument type index
+ * that is present.  The iterator's this_arg member points to the start of the
+ * argument associated with the current argument index that is present,
+ * which can be found in the iterator's this_arg_index member.  This arg
+ * index corresponds to the IEEE80211_RADIOTAP_... defines.
+ */
+
+
+int ieee80211_radiotap_iterator_init(
+        struct ieee80211_radiotap_iterator * iterator,
+        struct ieee80211_radiotap_header * radiotap_header,
+        int max_length)
+{
+        if(iterator == NULL)
+                return (-EINVAL);
+
+        if(radiotap_header == NULL)
+                return (-EINVAL);
+        /* Linux only supports version 0 radiotap format */
+
+        if (radiotap_header->it_version)
+                return (-EINVAL);
+
+        /* sanity check for allowed length and radiotap length field */
+
+        if (max_length < (le16_to_cpu(radiotap_header->it_len)))
+                return (-EINVAL);
+
+        iterator->rtheader = radiotap_header;
+        iterator->max_length = le16_to_cpu(radiotap_header->it_len);
+        iterator->arg_index = 0;
+        iterator->bitmap_shifter = le32_to_cpu(radiotap_header->it_present);
+        iterator->arg = ((u8 *)radiotap_header) +
+                        sizeof (struct ieee80211_radiotap_header);
+        iterator->this_arg = 0;
+
+        /* find payload start allowing for extended bitmap(s) */
+
+        if (unlikely(iterator->bitmap_shifter &
+            IEEE80211_RADIOTAP_PRESENT_EXTEND_MASK)) {
+                while (le32_to_cpu(*((u32 *)iterator->arg)) &
+                    IEEE80211_RADIOTAP_PRESENT_EXTEND_MASK) {
+                        iterator->arg += sizeof (u32);
+
+                        /*
+                         * check for insanity where the present bitmaps
+                         * keep claiming to extend up to or even beyond the
+                         * stated radiotap header length
+                         */
+
+                        if ((((void*)iterator->arg) - ((void*)iterator->rtheader)) >
+                            iterator->max_length)
+                                return (-EINVAL);
+
+                }
+
+                iterator->arg += sizeof (u32);
+
+                /*
+                 * no need to check again for blowing past stated radiotap
+                 * header length, becuase ieee80211_radiotap_iterator_next
+                 * checks it before it is dereferenced
+                 */
+
+        }
+
+        /* we are all initialized happily */
+
+        return (0);
+}
+
+
+/**
+ * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg
+ * @iterator: radiotap_iterator to move to next arg (if any)
+ *
+ * Returns: next present arg index on success or negative if no more or error
+ *
+ * This function returns the next radiotap arg index (IEEE80211_RADIOTAP_...)
+ * and sets iterator->this_arg to point to the payload for the arg.  It takes
+ * care of alignment handling and extended present fields.  interator->this_arg
+ * can be changed by the caller.  The args pointed to are in little-endian
+ * format.
+ */
+
+int ieee80211_radiotap_iterator_next(
+        struct ieee80211_radiotap_iterator * iterator)
+{
+
+        /*
+         * small length lookup table for all radiotap types we heard of
+         * starting from b0 in the bitmap, so we can walk the payload
+         * area of the radiotap header
+         *
+         * There is a requirement to pad args, so that args
+         * of a given length must begin at a boundary of that length
+         * -- but note that compound args are allowed (eg, 2 x u16
+         * for IEEE80211_RADIOTAP_CHANNEL) so total arg length is not
+         * a reliable indicator of alignment requirement.
+         *
+         * upper nybble: content alignment for arg
+         * lower nybble: content length for arg
+         */
+
+        static const u8 rt_sizes[] = {
+                [IEEE80211_RADIOTAP_TSFT] = 0x88,
+                [IEEE80211_RADIOTAP_FLAGS] = 0x11,
+                [IEEE80211_RADIOTAP_RATE] = 0x11,
+                [IEEE80211_RADIOTAP_CHANNEL] = 0x24,
+                [IEEE80211_RADIOTAP_FHSS] = 0x22,
+                [IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = 0x11,
+                [IEEE80211_RADIOTAP_DBM_ANTNOISE] = 0x11,
+                [IEEE80211_RADIOTAP_LOCK_QUALITY] = 0x22,
+                [IEEE80211_RADIOTAP_TX_ATTENUATION] = 0x22,
+                [IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = 0x22,
+                [IEEE80211_RADIOTAP_DBM_TX_POWER] = 0x11,
+                [IEEE80211_RADIOTAP_ANTENNA] = 0x11,
+                [IEEE80211_RADIOTAP_DB_ANTSIGNAL] = 0x11,
+                [IEEE80211_RADIOTAP_DB_ANTNOISE] = 0x11,
+                [IEEE80211_RADIOTAP_TX_FLAGS] = 0x22,
+                [IEEE80211_RADIOTAP_RX_FLAGS] = 0x22,
+                [IEEE80211_RADIOTAP_RTS_RETRIES] = 0x11,
+                [IEEE80211_RADIOTAP_DATA_RETRIES] = 0x11
+                /*
+                 * add more here as they are defined in
+                 * include/net/ieee80211_radiotap.h
+                 */
+        };
+
+        /*
+         * for every radiotap entry we can at
+         * least skip (by knowing the length)...
+         */
+
+        while (iterator->arg_index < (int)sizeof (rt_sizes)) {
+                int hit = 0;
+
+                if (!(iterator->bitmap_shifter & 1))
+                        goto next_entry; /* arg not present */
+
+                /*
+                 * arg is present, account for alignment padding
+                 *  8-bit args can be at any alignment
+                 * 16-bit args must start on 16-bit boundary
+                 * 32-bit args must start on 32-bit boundary
+                 * 64-bit args must start on 64-bit boundary
+                 *
+                 * note that total arg size can differ from alignment of
+                 * elements inside arg, so we use upper nybble of length
+                 * table to base alignment on
+                 *
+                 * also note: these alignments are ** relative to the
+                 * start of the radiotap header **.  There is no guarantee
+                 * that the radiotap header itself is aligned on any
+                 * kind of boundary.
+                 */
+
+                if ((((void*)iterator->arg)-((void*)iterator->rtheader)) &
+                    ((rt_sizes[iterator->arg_index] >> 4) - 1))
+                        iterator->arg_index +=
+                                (rt_sizes[iterator->arg_index] >> 4) -
+                                ((((void*)iterator->arg) -
+                                ((void*)iterator->rtheader)) &
+                                ((rt_sizes[iterator->arg_index] >> 4) - 1));
+
+                /*
+                 * this is what we will return to user, but we need to
+                 * move on first so next call has something fresh to test
+                 */
+
+                iterator->this_arg_index = iterator->arg_index;
+                iterator->this_arg = iterator->arg;
+                hit = 1;
+
+                /* internally move on the size of this arg */
+
+                iterator->arg += rt_sizes[iterator->arg_index] & 0x0f;
+
+                /*
+                 * check for insanity where we are given a bitmap that
+                 * claims to have more arg content than the length of the
+                 * radiotap section.  We will normally end up equalling this
+                 * max_length on the last arg, never exceeding it.
+                 */
+
+                if ((((void*)iterator->arg) - ((void*)iterator->rtheader)) >
+                    iterator->max_length)
+                        return (-EINVAL);
+
+        next_entry:
+
+                iterator->arg_index++;
+                if (unlikely((iterator->arg_index & 31) == 0)) {
+                        /* completed current u32 bitmap */
+                        if (iterator->bitmap_shifter & 1) {
+                                /* b31 was set, there is more */
+                                /* move to next u32 bitmap */
+                                iterator->bitmap_shifter = le32_to_cpu(
+                                        *iterator->next_bitmap);
+                                iterator->next_bitmap++;
+                        } else {
+                                /* no more bitmaps: end */
+                                iterator->arg_index = sizeof (rt_sizes);
+                        }
+                } else { /* just try the next bit */
+                        iterator->bitmap_shifter >>= 1;
+                }
+
+                /* if we found a valid arg earlier, return it now */
+
+                if (hit)
+                        return (iterator->this_arg_index);
+
+        }
+
+        /* we don't know how to handle any more args, we're done */
+
+        return (-1);
+}