Merge #560

560: IEEE802154: getters for security fields r=Dirbaio a=thibautvdv

This adds getters for the security fields of the IEEE802154 frame. Also added a test for it.

`src/wire/ieee802154.rs` also contained a function for calculating the CRC. However, this is not needed and thus I also remove it in this PR.

Co-authored-by: Thibaut Vandervelden <thvdveld@vub.be>

src/wire/ieee802154.rs

@@ -6,45 +6,6 @@ use crate::wire::ipv6::Address as Ipv6Address;
 use crate::Error;
 use crate::Result;
 
-const CRC_TABLE: [u16; 256] = [
-    0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf, 0x8c48, 0x9dc1, 0xaf5a, 0xbed3,
-    0xca6c, 0xdbe5, 0xe97e, 0xf8f7, 0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
-    0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876, 0x2102, 0x308b, 0x0210, 0x1399,
-    0x6726, 0x76af, 0x4434, 0x55bd, 0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
-    0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c, 0xbdcb, 0xac42, 0x9ed9, 0x8f50,
-    0xfbef, 0xea66, 0xd8fd, 0xc974, 0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
-    0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3, 0x5285, 0x430c, 0x7197, 0x601e,
-    0x14a1, 0x0528, 0x37b3, 0x263a, 0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
-    0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9, 0xef4e, 0xfec7, 0xcc5c, 0xddd5,
-    0xa96a, 0xb8e3, 0x8a78, 0x9bf1, 0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
-    0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70, 0x8408, 0x9581, 0xa71a, 0xb693,
-    0xc22c, 0xd3a5, 0xe13e, 0xf0b7, 0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
-    0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036, 0x18c1, 0x0948, 0x3bd3, 0x2a5a,
-    0x5ee5, 0x4f6c, 0x7df7, 0x6c7e, 0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
-    0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd, 0xb58b, 0xa402, 0x9699, 0x8710,
-    0xf3af, 0xe226, 0xd0bd, 0xc134, 0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
-    0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3, 0x4a44, 0x5bcd, 0x6956, 0x78df,
-    0x0c60, 0x1de9, 0x2f72, 0x3efb, 0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
-    0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a, 0xe70e, 0xf687, 0xc41c, 0xd595,
-    0xa12a, 0xb0a3, 0x8238, 0x93b1, 0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
-    0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330, 0x7bc7, 0x6a4e, 0x58d5, 0x495c,
-    0x3de3, 0x2c6a, 0x1ef1, 0x0f78,
-];
-
-pub fn calculate_crc(buffer: &[u8]) -> u16 {
-    fn crc_byte(crc: u16, c: u8) -> u16 {
-        (crc >> 8) ^ CRC_TABLE[((crc ^ (c as u16)) & 0xff) as usize]
-    }
-
-    let mut crc = 0;
-
-    for b in buffer {
-        crc = crc_byte(crc, *b);
-    }
-
-    crc
-}
-
 enum_with_unknown! {
     /// IEEE 802.15.4 frame type.
     pub enum FrameType(u8) {
@@ -288,7 +249,8 @@ impl<T: AsRef<[u8]>> Frame<T> {
     /// Ensure that no accessor method will panic if called.
     /// Returns `Err(Error::Truncated)` if the buffer is too short.
     pub fn check_len(&self) -> Result<()> {
-        if self.buffer.as_ref().is_empty() {
+        // We need at least 3 bytes
+        if self.buffer.as_ref().len() < 3 {
             Err(Error::Truncated)
         } else {
             Ok(())
@@ -476,27 +438,118 @@ impl<T: AsRef<[u8]>> Frame<T> {
         }
     }
 
-    /// Return the Auxilliary Security Header Field
-    #[inline]
-    pub fn aux_security_header(&self) -> Option<&[u8]> {
-        match self.frame_type() {
-            FrameType::Beacon
-            | FrameType::Data
-            | FrameType::MacCommand
-            | FrameType::Multipurpose => (),
-            FrameType::Acknowledgement if self.frame_version() == FrameVersion::Ieee802154 => (),
-            FrameType::Acknowledgement
-            | FrameType::Extended
-            | FrameType::FragmentOrFrak
-            | FrameType::Unknown(_) => return None,
+    /// Return the index where the auxiliary security header starts.
+    fn aux_security_header_start(&self) -> usize {
+        // We start with 3, because 2 bytes for frame control and the sequence number.
+        let mut index = 3;
+        index += self.addressing_fields().unwrap().len();
+        index
+    }
+
+    /// Return the index where the payload starts.
+    fn payload_start(&self) -> usize {
+        let mut index = self.aux_security_header_start();
+
+        if self.security_enabled() {
+            // We add 5 because 1 byte for control bits and 4 bytes for frame counter.
+            index += 5;
+            index += if let Some(len) = self.key_identifier_length() {
+                len as usize
+            } else {
+                0
+            };
         }
 
-        if !self.security_enabled() {
-            return None;
+        index
+    }
+
+    /// Return the lenght of the key identifier field.
+    fn key_identifier_length(&self) -> Option<u8> {
+        Some(match self.key_identifier_mode() {
+            0 => 0,
+            1 => 1,
+            2 => 5,
+            3 => 9,
+            _ => return None,
+        })
+    }
+
+    /// Return the security level of the auxiliary security header.
+    pub fn security_level(&self) -> u8 {
+        let index = self.aux_security_header_start();
+        let b = self.buffer.as_ref()[index..][0];
+        b & 0b111
+    }
+
+    /// Return the key identifier mode used by the auxiliary security header.
+    pub fn key_identifier_mode(&self) -> u8 {
+        let index = self.aux_security_header_start();
+        let b = self.buffer.as_ref()[index..][0];
+        (b >> 3) & 0b11
+    }
+
+    /// Return the frame counter field.
+    pub fn frame_counter(&self) -> u32 {
+        let index = self.aux_security_header_start();
+        let b = &self.buffer.as_ref()[index..];
+        LittleEndian::read_u32(&b[1..1 + 4])
+    }
+
+    /// Return the Key Identifier field.
+    fn key_identifier(&self) -> &[u8] {
+        let index = self.aux_security_header_start();
+        let b = &self.buffer.as_ref()[index..];
+        let length = if let Some(len) = self.key_identifier_length() {
+            len as usize
+        } else {
+            0
+        };
+        &b[5..][..length]
+    }
+
+    /// Return the Key Source field.
+    pub fn key_source(&self) -> Option<&[u8]> {
+        let ki = self.key_identifier();
+        let len = ki.len();
+        if len > 1 {
+            Some(&ki[..len - 1])
+        } else {
+            None
+        }
+    }
+
+    /// Return the Key Index field.
+    pub fn key_index(&self) -> Option<u8> {
+        let ki = self.key_identifier();
+        let len = ki.len();
+
+        if len > 0 {
+            Some(ki[len - 1])
+        } else {
+            None
         }
+    }
+
+    /// Return the Message Integrity Code (MIC).
+    pub fn message_integrity_code(&self) -> Option<&[u8]> {
+        let mic_len = match self.security_level() {
+            0 | 4 => return None,
+            1 | 5 => 4,
+            2 | 6 => 8,
+            3 | 7 => 16,
+            _ => panic!(),
+        };
+
+        let data = &self.buffer.as_ref();
+        let len = data.len();
 
-        net_debug!("Auxilliary security header is currently not supported.");
-        None
+        Some(&data[len - mic_len..])
+    }
+
+    /// Return the MAC header.
+    pub fn mac_header(&self) -> &[u8] {
+        let data = &self.buffer.as_ref();
+        &data[..self.payload_start()]
     }
 }
 
@@ -506,10 +559,10 @@ impl<'a, T: AsRef<[u8]> + ?Sized> Frame<&'a T> {
     pub fn payload(&self) -> Option<&'a [u8]> {
         match self.frame_type() {
             FrameType::Data => {
-                let data = &self.buffer.as_ref()[field::ADDRESSING];
-                let offset = self.addressing_fields().unwrap().len();
+                let index = self.payload_start();
+                let data = &self.buffer.as_ref();
 
-                Some(&data[offset..])
+                Some(&data[index..])
             }
             _ => None,
         }
@@ -652,12 +705,9 @@ impl<T: AsRef<[u8]> + AsMut<[u8]>> Frame<T> {
     pub fn payload_mut(&mut self) -> Option<&mut [u8]> {
         match self.frame_type() {
             FrameType::Data => {
-                let mut start_offset = 3;
-                start_offset += self.addressing_fields().unwrap().len();
-
+                let index = self.payload_start();
                 let data = self.buffer.as_mut();
-                let end_offset = start_offset + data.len() - 2;
-                Some(&mut data[start_offset..end_offset])
+                Some(&mut data[index..])
             }
             _ => None,
         }
@@ -892,6 +942,49 @@ mod test {
         dst_addressing_mode -> AddressingMode::Short,
         frame_version -> FrameVersion::Ieee802154_2006,
         src_addressing_mode -> AddressingMode::Extended,
-        //payload -> Some(&[0x2b, 0x00, 0x00, 0x00]),
+        payload -> Some(&[0x2b, 0x00, 0x00, 0x00][..]),
+    }
+
+    vector_test! {
+        security
+        [
+            0x69,0xdc, // frame control
+            0x32, // sequence number
+            0xcd,0xab, // destination PAN id
+            0xbf,0x9b,0x15,0x06,0x00,0x4b,0x12,0x00, // extended destination address
+            0xc7,0xd9,0xb5,0x14,0x00,0x4b,0x12,0x00, // extended source address
+            0x05, // security control field
+            0x31,0x01,0x00,0x00, // frame counter
+            0x3e,0xe8,0xfb,0x85,0xe4,0xcc,0xf4,0x48,0x90,0xfe,0x56,0x66,0xf7,0x1c,0x65,0x9e,0xf9, // data
+            0x93,0xc8,0x34,0x2e,// MIC
+        ];
+        frame_type -> FrameType::Data,
+        security_enabled -> true,
+        frame_pending -> false,
+        ack_request -> true,
+        pan_id_compression -> true,
+        dst_addressing_mode -> AddressingMode::Extended,
+        frame_version -> FrameVersion::Ieee802154_2006,
+        src_addressing_mode -> AddressingMode::Extended,
+        dst_pan_id -> Some(Pan(0xabcd)),
+        dst_addr -> Some(Address::Extended([0x00,0x12,0x4b,0x00,0x06,0x15,0x9b,0xbf])),
+        src_pan_id -> None,
+        src_addr -> Some(Address::Extended([0x00,0x12,0x4b,0x00,0x14,0xb5,0xd9,0xc7])),
+        security_level -> 5,
+        key_identifier_mode -> 0,
+        frame_counter -> 305,
+        key_source -> None,
+        key_index -> None,
+        payload -> Some(&[0x3e,0xe8,0xfb,0x85,0xe4,0xcc,0xf4,0x48,0x90,0xfe,0x56,0x66,0xf7,0x1c,0x65,0x9e,0xf9,0x93,0xc8,0x34,0x2e][..]),
+        message_integrity_code -> Some(&[0x93, 0xC8, 0x34, 0x2E][..]),
+        mac_header -> &[
+            0x69,0xdc, // frame control
+            0x32, // sequence number
+            0xcd,0xab, // destination PAN id
+            0xbf,0x9b,0x15,0x06,0x00,0x4b,0x12,0x00, // extended destination address
+            0xc7,0xd9,0xb5,0x14,0x00,0x4b,0x12,0x00, // extended source address
+            0x05, // security control field
+            0x31,0x01,0x00,0x00, // frame counter
+        ][..],
     }
 }