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tweaking dns question parsing

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This commit is contained in:
Andy Pack 2024-01-29 23:19:09 +00:00
parent 7cf99b610a
commit 1f6593263a
Signed by: sarsoo
GPG Key ID: A55BA3536A5E0ED7
6 changed files with 114 additions and 84 deletions
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128
dnstp/src/dns_question.rs
View File

@ -2,7 +2,7 @@ use std::ops::Sub;
use urlencoding::{encode, decode};
#[derive(Ord, PartialOrd, Eq, PartialEq, Debug, Copy, Clone)]
enum QType {
pub enum QType {
A = 1,
NS = 2,
CNAME = 5,
@ -42,7 +42,7 @@ impl TryFrom<u8> for QType {
}
#[derive(Ord, PartialOrd, Eq, PartialEq, Debug, Copy, Clone)]
enum QClass {
pub enum QClass {
Internet = 1,
Chaos = 3,
Hesiod = 4,
@ -62,7 +62,7 @@ impl TryFrom<u8> for QClass {
}
#[derive(Ord, PartialOrd, Eq, PartialEq, Debug)]
struct DNSQuestion {
pub struct DNSQuestion {
qname: String,
qtype: QType,
qclass: QClass
@ -102,9 +102,9 @@ impl DNSQuestion {
}
}
pub fn questions_from_bytes(bytes: Vec<u8>, total_questions: u8) -> Result<Vec<DNSQuestion>, ()>
pub fn questions_from_bytes(bytes: Vec<u8>, total_questions: u16) -> Result<Vec<DNSQuestion>, ()>
{
if (bytes.len() < 4)
if bytes.len() < 4
{
return Err(());
}
@ -117,90 +117,71 @@ pub fn questions_from_bytes(bytes: Vec<u8>, total_questions: u8) -> Result<Vec<D
let mut current_qtype: Option<u8> = None;
let mut current_qclass: Option<u8> = None;
let mut trailers_reached = false;
// let mut finished = false;
for byte in bytes {
match current_length {
None => { // next question, init lengths
current_length = Some(byte);
remaining_length = Box::from(byte);
current_query = Some(Vec::with_capacity(10));
}
Some(_) => {
if byte == 0 {
trailers_reached = true;
continue
}
if *remaining_length == 0 && !trailers_reached {
current_query.as_mut().unwrap().push('.' as u8);
if questions.len() != total_questions as usize {
match current_length {
None => { // next question, init lengths
current_length = Some(byte);
remaining_length = Box::from(byte);
current_query = Some(Vec::with_capacity(10));
}
else if trailers_reached { // trailer fields
match current_qtype {
None => {
current_qtype = Some(byte);
}
Some(qtype_b) => {
match current_qclass {
None => {
current_qclass = Some(byte);
}
Some(qclass_b) => {
Some(_) => {
if byte == 0 {
trailers_reached = true;
continue
}
match (qtype_b.try_into(), qclass_b.try_into()) {
(Ok(qtype), Ok(qclass)) => {
questions.push(DNSQuestion {
qname: String::from_utf8(current_query.unwrap()).unwrap(),
qtype,
qclass
});
if *remaining_length == 0 && !trailers_reached {
current_query.as_mut().unwrap().push('.' as u8);
current_length = Some(byte);
remaining_length = Box::from(byte);
}
else if trailers_reached { // trailer fields
match current_qtype {
None => {
current_qtype = Some(byte);
}
Some(qtype_b) => {
match current_qclass {
None => {
// current_qclass = Some(byte);
match (qtype_b.try_into(), byte.try_into()) {
(Ok(qtype), Ok(qclass)) => {
questions.push(DNSQuestion {
qname: String::from_utf8(current_query.unwrap()).unwrap(),
qtype,
qclass
});
current_length = Some(byte);
remaining_length = Box::from(byte);
current_query = Some(Vec::with_capacity(10));
current_qtype = None;
current_qclass = None;
trailers_reached = false;
}
_ => {
return Err(());
current_length = None;
remaining_length = Box::from(byte);
current_query = None;
current_qtype = None;
current_qclass = None;
trailers_reached = false;
}
_ => {
return Err(());
}
}
}
Some(_) => {
}
}
}
}
} else {
current_query.as_mut().unwrap().push(byte);
*remaining_length = remaining_length.sub(1);
}
}
else
{
current_query.as_mut().unwrap().push(byte);
*remaining_length = remaining_length.sub(1);
}
}
}
}
match (current_qtype, current_qclass) {
(Some(qtype), Some(qclass)) => {
match (qtype.try_into(), qclass.try_into()) {
(Ok(qtype), Ok(qclass)) => {
questions.push(DNSQuestion {
qname: String::from_utf8(current_query.unwrap()).unwrap(),
qtype,
qclass
});
}
_ => {
return Err(());
}
}
}
_ => {
return Err(());
}
}
Ok(questions)
}
@ -216,7 +197,8 @@ mod tests {
qtype: QType::A
};
let q_bytes = q.to_bytes();
let mut q_bytes = q.to_bytes();
q_bytes.append(&mut vec![0, 0, 0, 0, 0, 0]);
let q_reconstructed = questions_from_bytes(q_bytes, 1).unwrap();
@ -282,7 +264,7 @@ mod tests {
q_bytes.append(&mut q2_bytes);
q_bytes.append(&mut q3_bytes);
let q_reconstructed = questions_from_bytes(q_bytes, 2).unwrap();
let q_reconstructed = questions_from_bytes(q_bytes, 3).unwrap();
assert_eq!(q.qname, q_reconstructed[0].qname);
assert_eq!(q.qclass, q_reconstructed[0].qclass);

10
dnstp/src/dns_request.rs Normal file
View File

@ -0,0 +1,10 @@
use std::net::SocketAddr;
use crate::dns_header::DNSHeader;
use crate::dns_question::DNSQuestion;
#[derive(Ord, PartialOrd, Eq, PartialEq, Debug)]
pub struct DNSRequest {
pub header: DNSHeader,
pub questions: Vec<DNSQuestion>,
pub peer: SocketAddr
}

5
dnstp/src/dns_socket.rs
View File

@ -1,5 +1,4 @@
use std::net::{SocketAddr, UdpSocket};
use std::ptr::read;
use std::thread;
use std::thread::{JoinHandle};
use log::{debug, error, info};
@ -83,8 +82,8 @@ impl DNSSocket {
match res {
Ok((read_count, peer)) => {
let res_str = str::from_utf8(&(*buf)).unwrap();
info!("received [{}] from [{}]", res_str, peer);
// let res_str = str::from_utf8(&(*buf)).unwrap();
// info!("received [{}] from [{}]", res_str, peer);
if read_count > HEADER_SIZE {
message_sender.send(Box::new(NetworkMessage {

5
dnstp/src/lib.rs
View File

@ -1,7 +1,8 @@
pub mod dns_socket;
pub mod request_parser;
mod dns_header;
pub mod dns_header;
pub mod request_processor;
pub mod response_processor;
pub mod raw_request;
mod dns_question;
pub mod dns_question;
pub mod dns_request;

27
dnstp/src/request_parser.rs
View File

@ -1,5 +1,8 @@
use crate::dns_header::{Direction, DNSHeader, Opcode, ResponseCode};
use crate::dns_header::Direction::Response;
use crate::dns_question::{DNSQuestion, questions_from_bytes};
use crate::dns_request::DNSRequest;
use crate::raw_request::NetworkMessage;
fn two_byte_extraction(buffer: &[u8], idx: usize) -> u16
{
@ -114,6 +117,30 @@ pub fn parse_header_to_bytes(header: &DNSHeader) -> [u8; 12]
header_bytes
}
pub fn parse_request(msg: NetworkMessage) -> Result<DNSRequest, ()>
{
let header = parse_header(msg.buffer[0..12].try_into().unwrap());
match header {
Ok(header) => {
let mut trimmed = msg.buffer.to_vec();
trimmed.drain(0 .. 12);
match questions_from_bytes(trimmed, header.question_count)
{
Ok(questions) => {
Ok(DNSRequest {
header,
questions,
peer: msg.peer
})
}
Err(_) => Err(())
}
},
Err(_) => Err(())
}
}
#[cfg(test)]
mod tests {
use super::*;

23
dnstp/src/request_processor.rs
View File

@ -1,9 +1,11 @@
use std::sync::mpsc;
use std::sync::mpsc::{Receiver, Sender};
use std::thread;
use log::info;
use log::{error, info};
use std::str;
use crate::dns_request::DNSRequest;
use crate::raw_request::NetworkMessagePtr;
use crate::request_parser::parse_request;
pub struct RequestProcesor {
message_channel: Option<Sender<NetworkMessagePtr>>
@ -25,14 +27,23 @@ impl RequestProcesor {
for mut m in rx
{
info!("processing: {}", str::from_utf8(&(*(*m).buffer)).unwrap());
// info!("processing: {}", str::from_utf8(&(*(*m).buffer)).unwrap());
(*(*m).buffer).reverse();
let request = parse_request(*m);
match sending_channel.send(m) {
Ok(_) => {}
Err(_) => {}
match request {
Ok(r) => {
info!("received dns message: {:?}", r);
}
Err(_) => {
error!("failed to parse message");
}
}
// match sending_channel.send(m) {
// Ok(_) => {}
// Err(_) => {}
// }
}
info!("message processing thread finishing")