Add RadioTapParser class

src/utils/radiotap_parser.cpp

@@ -0,0 +1,264 @@
+/*
+ * Copyright (c) 2017, Matias Fontanini
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * * 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.
+ *
+ * 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.
+ *
+ */
+
+#include "utils/radiotap_parser.h"
+#include "exceptions.h"
+
+using std::vector;
+
+namespace Tins {
+namespace Utils {
+
+struct FieldMetadata {
+    uint32_t size;
+    uint32_t alignment;
+};
+
+static const FieldMetadata RADIOTAP_METADATA[] = {
+    { 8, 8 }, /// TSFT
+    { 1, 1 }, // FLAGS
+    { 1, 1 }, // RATE
+    { 4, 2 }, // CHANNEL
+    { 2, 2 }, // FHSS
+    { 1, 1 }, // DBM_SIGNAL
+    { 1, 1 }, // DBM_NOISE
+    { 2, 2 }, // LOCK_QUALITY
+    { 2, 2 }, // TX_ATTENUATION
+    { 2, 2 }, // DB_TX_ATTENUATION
+    { 1, 1 }, // DBM_TX_ATTENUATION
+    { 1, 1 }, // ANTENNA
+    { 1, 1 }, // DB_SIGNAL
+    { 1, 1 }, // DB_NOISE
+    { 2, 2 }, // RX_FLAGS
+    { 2, 2 }, // TX_FLAGS
+    { 1, 1 }, // RTS_RETRIES
+    { 1, 1 }, // DATA_RETRIES
+    { 4, 4 }, // CHANNEL_PLUS
+    { 3, 1 }, // MCS
+};
+
+static const uint64_t BIT_LIMIT = sizeof(RADIOTAP_METADATA) / sizeof(FieldMetadata) + 1;
+
+#if TINS_IS_LITTLE_ENDIAN
+TINS_BEGIN_PACK
+struct RadioTapFlags {
+    uint32_t
+        tsft:1,
+        flags:1,
+        rate:1,
+        channel:1,
+        fhss:1,
+        dbm_signal:1,
+        dbm_noise:1,
+        lock_quality:1,
+
+        tx_attenuation:1,
+        db_tx_attenuation:1,
+        dbm_tx_power:1,
+        antenna:1,
+        db_signal:1,
+        db_noise:1,
+        rx_flags:1,
+        tx_flags:1,
+
+        reserved1:1,
+        data_retries:1,
+        channel_plus:1,
+        mcs:1,
+        reserved2:4,
+
+        reserved3:7,
+        ext:1;
+} TINS_END_PACK;
+#else
+TINS_BEGIN_PACK
+struct RadioTapFlags {
+    uint32_t
+        lock_quality:1,
+        dbm_noise:1,
+        dbm_signal:1,
+        fhss:1,
+        channel:1,
+        rate:1,
+        flags:1,
+        tsft:1,
+
+        tx_flags:1,
+        rx_flags:1,
+        db_noise:1,
+        db_signal:1,
+        antenna:1,
+        dbm_tx_power:1,
+        db_tx_attenuation:1,
+        tx_attenuation:1,
+
+        reserved2:4,
+        mcs:1,
+        channel_plus:1,
+        data_retries:1,
+        reserved1:1,
+
+        ext:1,
+        reserved3:7;
+} TINS_END_PACK;
+#endif
+
+void align_buffer(const uint8_t* buffer_start, const uint8_t*& buffer, uint32_t size, size_t n) {
+    uint32_t offset = ((buffer - buffer_start) % n);
+    if (offset) {
+        offset = n - offset;
+        if (offset > size) {
+            throw malformed_packet();
+        }
+        buffer += offset;
+    }
+}
+
+RadioTapParser::RadioTapParser(const vector<uint8_t>& buffer)
+: current_namespace_(RADIOTAP_NS), current_bit_(0), namespace_index_(0) {
+    if (TINS_UNLIKELY(buffer.empty())) {
+        throw malformed_packet();
+    }
+    start_ = &*buffer.begin();
+    end_ = start_ + buffer.size();
+    const size_t max_size = end_ - start_;
+    if (TINS_UNLIKELY(max_size < sizeof(RadiotapHeader))) {
+        throw malformed_packet();
+    }
+    const RadiotapHeader* radio = (const RadiotapHeader*)start_;
+    end_ = start_ + Endian::le_to_host(radio->length);
+    current_ptr_ = find_options_start();
+    // Skip all fields and make this point to the first flags one
+    advance_to_next_field(true /* start from bit zero */);
+}
+
+RadioTapParser::NamespaceType RadioTapParser::current_namespace() const {
+    return current_namespace_;
+}
+
+RadioTap::PresentFlags RadioTapParser::current_field() const {
+    return static_cast<RadioTap::PresentFlags>(1 << current_bit_);
+}
+
+RadioTapParser::option RadioTapParser::current_option() {
+    const uint32_t size = RADIOTAP_METADATA[current_bit_].size;
+    if (TINS_UNLIKELY(current_ptr_ + size > end_)) {
+        throw malformed_packet();
+    }
+    return option(current_field(), size, current_ptr_);
+}
+
+bool RadioTapParser::advance_field() {
+    // If we manage to advance the field, return true
+    if (advance_to_next_field(false /* keep going from current */)) {
+        return true;
+    }
+    // Otherwise, let's try advancing the namespace. If we fail, then we failed
+    if (!advance_to_next_namespace()) {
+        return false;
+    }
+    // Otherwise restart bit and try to find the first field in this namespace
+    current_bit_ = 0;
+    return advance_to_next_field(true /* start from 0*/);
+}
+
+const uint8_t* RadioTapParser::find_options_start() const {
+    uint32_t total_sz = end_ - start_;
+    if (TINS_UNLIKELY(total_sz < sizeof(RadiotapHeader))) {
+        throw malformed_packet();
+    }
+    // Skip fields before the flags one
+    const RadioTapFlags* flags = get_flags_ptr();
+    while (flags->ext == 1) {
+        if (TINS_UNLIKELY(total_sz < sizeof(RadioTapFlags))) {
+            throw malformed_packet();
+        }
+        ++flags;
+        total_sz -= sizeof(RadioTapFlags);
+    }
+    return reinterpret_cast<const uint8_t*>(flags) + sizeof(RadioTapFlags);
+}
+
+bool RadioTapParser::advance_to_next_field(bool start_from_zero) {
+    const RadioTapFlags* flags = get_flags_ptr();
+    uint64_t bit;
+    if (start_from_zero) {
+        bit = 0;
+    }
+    else {
+        // Skip the payload
+        current_ptr_ += RADIOTAP_METADATA[current_bit_].size;
+        bit = current_bit_ + 1;
+    }
+    while (!is_field_set(1 << bit, flags) && bit < BIT_LIMIT) {
+        bit++; 
+    }
+    if (bit < BIT_LIMIT) {
+        // Skip and align the buffer
+        align_buffer(start_, current_ptr_, end_ - start_, RADIOTAP_METADATA[bit].alignment);
+        current_bit_ = bit;
+        return true;
+    }
+    return false;
+}
+
+bool RadioTapParser::advance_to_next_namespace() {
+    const uint32_t initial_index = namespace_index_;
+    while (get_flags_ptr()->ext == 1) {
+        const RadioTapFlags* flags = get_flags_ptr();
+        if (is_field_set(29, flags)) {
+            current_namespace_ = RADIOTAP_NS;
+        }
+        else if (is_field_set(30, flags)) {
+            current_namespace_ = VENDOR_NS;
+        }
+        else {
+            current_namespace_ = UNKNOWN_NS;
+        }
+        namespace_index_++;
+    }
+    return initial_index != namespace_index_;
+}
+
+bool RadioTapParser::is_field_set(uint32_t bit, const RadioTapFlags* flags) const {
+    TINS_BEGIN_PACK
+    union FlagsUnion {
+        RadioTapFlags* flags;
+        uint32_t flags_32;
+    } TINS_END_PACK;
+    const FlagsUnion* flags_union = reinterpret_cast<const FlagsUnion*>(flags); 
+    return (Endian::le_to_host(flags_union->flags_32) & bit) != 0;
+}
+
+const RadioTapFlags* RadioTapParser::get_flags_ptr() const {
+    return (const RadioTapFlags*)(start_ + sizeof(uint32_t) * (namespace_index_ + 1));
+}
+
+} // Utils
+} // Tins