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use nom::number;
use nom::IResult;
/******************************************************************************
* Struct
******************************************************************************/
/*
* User Datagram 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
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Source Port | Destination Port |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Length | Checksum |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Data |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct UdpHeader {
pub src_port: u16,
pub dst_port: u16,
pub length: u16,
pub checksum: u16,
}
/******************************************************************************
* Parse
******************************************************************************/
pub fn parse_udp(input: &[u8]) -> IResult<&[u8], UdpHeader> {
let (input, src_port) = number::streaming::be_u16(input)?;
let (input, dst_port) = number::streaming::be_u16(input)?;
let (input, length) = number::streaming::be_u16(input)?;
let (input, checksum) = number::streaming::be_u16(input)?;
Ok((
input,
UdpHeader {
src_port,
dst_port,
length,
checksum,
},
))
}
/******************************************************************************
* TEST
******************************************************************************/
#[cfg(test)]
mod tests {
use super::parse_udp;
use super::UdpHeader;
const LAST_SLICE: &'static [u8] = &[0xff];
#[test]
fn parse_udp_works() {
/*
* User Datagram Protocol, Src Port: 9993, Dst Port: 9993
* Source Port: 9993
* Destination Port: 9993
* Length: 145
* Checksum: 0x57d3 [correct]
* [Calculated Checksum: 0x57d3]
* [Checksum Status: Good]
* [Stream index: 3]
* [Timestamps]
* [Time since first frame: 0.000000000 seconds]
* [Time since previous frame: 0.000000000 seconds]
* UDP payload (137 bytes)
* Data (137 bytes)
*/
let bytes = [
0x27, 0x09, /* Source Port */
0x27, 0x09, /* Destination Port */
0x00, 0x91, /* Length */
0x57, 0xd3, /* Checksum */
0xff, /* Payload */
];
let expectation = UdpHeader {
src_port: 9993,
dst_port: 9993,
length: 145,
checksum: 0x57d3,
};
assert_eq!(parse_udp(&bytes), Ok((LAST_SLICE, expectation)));
}
}
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