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use super::{buffer::PacketBuffer, result::ResultCode};
use crate::Result;
#[derive(Clone, Debug)]
pub struct DnsHeader {
pub id: u16, // 16 bits
pub recursion_desired: bool, // 1 bit
pub truncated_message: bool, // 1 bit
pub authoritative_answer: bool, // 1 bit
pub opcode: u8, // 4 bits
pub response: bool, // 1 bit
pub rescode: ResultCode, // 4 bits
pub checking_disabled: bool, // 1 bit
pub authed_data: bool, // 1 bit
pub z: bool, // 1 bit
pub recursion_available: bool, // 1 bit
pub questions: u16, // 16 bits
pub answers: u16, // 16 bits
pub authoritative_entries: u16, // 16 bits
pub resource_entries: u16, // 16 bits
}
impl DnsHeader {
pub fn new() -> Self {
Self {
id: 0,
recursion_desired: false,
truncated_message: false,
authoritative_answer: false,
opcode: 0,
response: false,
rescode: ResultCode::NOERROR,
checking_disabled: false,
authed_data: false,
z: false,
recursion_available: false,
questions: 0,
answers: 0,
authoritative_entries: 0,
resource_entries: 0,
}
}
pub fn read(&mut self, buffer: &mut PacketBuffer) -> Result<()> {
self.id = buffer.read_u16()?;
let flags = buffer.read_u16()?;
let a = (flags >> 8) as u8;
let b = (flags & 0xFF) as u8;
self.recursion_desired = (a & (1 << 0)) > 0;
self.truncated_message = (a & (1 << 1)) > 0;
self.authoritative_answer = (a & (1 << 2)) > 0;
self.opcode = (a >> 3) & 0x0F;
self.response = (a & (1 << 7)) > 0;
self.rescode = ResultCode::from_num(b & 0x0F);
self.checking_disabled = (b & (1 << 4)) > 0;
self.authed_data = (b & (1 << 5)) > 0;
self.z = (b & (1 << 6)) > 0;
self.recursion_available = (b & (1 << 7)) > 0;
self.questions = buffer.read_u16()?;
self.answers = buffer.read_u16()?;
self.authoritative_entries = buffer.read_u16()?;
self.resource_entries = buffer.read_u16()?;
// Return the constant header size
Ok(())
}
pub fn write(&self, buffer: &mut PacketBuffer) -> Result<()> {
buffer.write_u16(self.id)?;
buffer.write_u8(
(self.recursion_desired as u8)
| ((self.truncated_message as u8) << 1)
| ((self.authoritative_answer as u8) << 2)
| (self.opcode << 3)
| ((self.response as u8) << 7),
)?;
buffer.write_u8(
(self.rescode as u8)
| ((self.checking_disabled as u8) << 4)
| ((self.authed_data as u8) << 5)
| ((self.z as u8) << 6)
| ((self.recursion_available as u8) << 7),
)?;
buffer.write_u16(self.questions)?;
buffer.write_u16(self.answers)?;
buffer.write_u16(self.authoritative_entries)?;
buffer.write_u16(self.resource_entries)?;
Ok(())
}
}
|
