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|
use crate::protocol::ip::IPProtocol;
use nom::bits;
use nom::bytes;
use nom::error::Error;
use nom::number;
use nom::sequence;
use nom::IResult;
use std::convert::TryFrom;
use std::net::Ipv6Addr;
/******************************************************************************
* Struct
******************************************************************************/
/*
* IPv6 Header Format
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Version| Traffic Class | Flow Label |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Payload Length | Next Header | Hop Limit |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* + +
* | |
* + Source Address +
* | |
* + +
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* + +
* | |
* + Destination Address +
* | |
* + +
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct IPv6Header {
pub version: u8, // 4 bit
pub dsc: u8, // Differentiated Services Codepoint: 6 bit
pub ecn: u8, // Explicit Congestion Notification: 2 bit
pub flow_label: u32, // 20 bit
pub length: u16,
pub next_header: IPProtocol,
pub hop_limit: u8,
pub source_address: Ipv6Addr,
pub dest_address: Ipv6Addr,
}
/******************************************************************************
* API
******************************************************************************/
fn half_byte_decode(input: &[u8]) -> IResult<&[u8], (u8, u8)> {
bits::bits::<_, _, Error<_>, _, _>(sequence::pair(
bits::streaming::take(4u8),
bits::streaming::take(4u8),
))(input)
}
fn address_v6_decode(input: &[u8]) -> IResult<&[u8], Ipv6Addr> {
let (input, ipv6) = bytes::streaming::take(16u8)(input)?;
Ok((input, Ipv6Addr::from(<[u8; 16]>::try_from(ipv6).unwrap())))
}
impl IPv6Header {
pub fn decode(input: &[u8]) -> IResult<&[u8], IPv6Header> {
let (input, ver_tc) = half_byte_decode(input)?;
let (input, tc_fl) = half_byte_decode(input)?;
let (input, fl): (_, u32) =
bits::bits::<_, _, Error<_>, _, _>(bits::streaming::take(16u8))(input)?;
let (input, length) = number::streaming::be_u16(input)?;
let (input, next_header) = IPProtocol::decode(input)?;
let (input, hop_limit) = number::streaming::be_u8(input)?;
let (input, source_address) = address_v6_decode(input)?;
let (input, dest_address) = address_v6_decode(input)?;
// TODO IPv6 Ext Header Decode
Ok((
input,
IPv6Header {
version: ver_tc.0,
dsc: (ver_tc.1 << 2) + ((tc_fl.0 & 0b1100) >> 2),
ecn: tc_fl.0 & 0b11,
flow_label: (u32::from(tc_fl.1) << 16) + fl,
length,
next_header,
hop_limit,
source_address,
dest_address,
},
))
}
}
/******************************************************************************
* TEST
******************************************************************************/
#[cfg(test)]
mod tests {
use super::IPv6Header;
use crate::protocol::ip::IPProtocol;
use std::net::Ipv6Addr;
const LAST_SLICE: &'static [u8] = &[0xff];
#[test]
fn ipv6_header_decode() {
/*
* Internet Protocol Version 6, Src: 2409:8034:4025::50:a31, Dst: 2409:8034:4040:5301::204
* 0110 .... = Version: 6
* .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
* .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
* .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
* .... 0000 0000 0000 0000 0000 = Flow Label: 0x00000
* Payload Length: 1416
* Next Header: UDP (17)
* Hop Limit: 252
* Source Address: 2409:8034:4025::50:a31
* Destination Address: 2409:8034:4040:5301::204
*/
let bytes = [
0x60, /* Version and Partial Differentiated Services Codepoint */
0x00, /* Partial Differentiated Services Codepoint and Explicit Congestion Notification and Partial Flow Label */
0x00, 0x00, /* Partial Flow Label */
0x05, 0x88, /* Payload Length */
0x11, /* Next Header */
0xfc, /* Hop Limit */
0x24, 0x09, 0x80, 0x34, 0x40, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x50,
0x0a, 0x31, /* Source Address */
0x24, 0x09, 0x80, 0x34, 0x40, 0x40, 0x53, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x02, 0x04, /* Destination Address */
0xff, /* Payload */
];
let expectation = IPv6Header {
version: 6,
dsc: 0,
ecn: 0,
flow_label: 0,
length: 1416,
next_header: IPProtocol::UDP,
hop_limit: 252,
source_address: Ipv6Addr::new(
0x2409, 0x8034, 0x4025, 0x0000, 0x0000, 0x0000, 0x0050, 0x0a31,
),
dest_address: Ipv6Addr::new(
0x2409, 0x8034, 0x4040, 0x5301, 0x0000, 0x0000, 0x0000, 0x0204,
),
};
assert_eq!(IPv6Header::decode(&bytes), Ok((LAST_SLICE, expectation)));
// example
let result = IPv6Header::decode(&bytes);
if let Ok((payload, header)) = result {
println!("return: {:?}, payload: {}", header, payload.len());
} else {
println!("return: Incomplete data");
}
}
}
|
