ishan/dns-server-rust
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added a basic, horrible dns proxy

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This commit is contained in:
Ishan Jain 2023-12-12 04:09:17 +05:30
parent 62238e5245
commit a929cfce73
Signed by: ishan
GPG Key ID: 0506DB2A1CC75C27
2 changed files with 56 additions and 61 deletions
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92
src/main.rs
View File

@ -6,49 +6,66 @@ use question::*;
mod rrecord;
use rrecord::*;
use std::net::UdpSocket;
use std::net::{SocketAddr, UdpSocket};
fn main() {
let args: Vec<String> = std::env::args().collect();
let resolver: SocketAddr = args[2].parse().unwrap();
println!("resolver = {:?}", resolver);
let upstream_socket =
UdpSocket::bind("0.0.0.0:31000").expect("Failed to bind to upstream address");
let udp_socket = UdpSocket::bind("127.0.0.1:2053").expect("Failed to bind to address");
let mut buf = [0; 512];
loop {
'outer: loop {
match udp_socket.recv_from(&mut buf) {
Ok((size, source)) => {
let received_data = &buf[0..size];
println!("Received {} bytes from {}", size, source);
let mut response = vec![];
let received_data = &buf[0..size];
let mut recv_packet = Packet::parse(received_data).unwrap();
upstream_socket
.send_to(received_data, resolver)
.expect("error in sending data to upstream");
println!("{:?}", recv_packet);
let mut lbuf = [0; 512];
recv_packet.header.query = true;
recv_packet.header.authoritative = false;
recv_packet.header.truncated = false;
recv_packet.header.recursion_avail = false;
recv_packet.header.reserved = 0;
recv_packet.header.rcode = if recv_packet.header.opcode == 0 { 0 } else { 4 };
recv_packet.header.an_count = recv_packet.header.qd_count;
recv_packet.header.authority_records = 0;
recv_packet.header.additional_records = 0;
match upstream_socket.recv_from(&mut lbuf) {
Ok((size, upstream)) => {
println!(
"Received {}bytes from {} on upstream socket",
size, upstream
);
for question in recv_packet.questions.iter() {
recv_packet.answers.push(RRecord {
name: question.name.clone(),
r_type: 1,
class: 1,
ttl: 1337,
rdlength: 4,
rdata: RData::A([0x8, 0x8, 0x8, 0x8]),
})
let mut recv_packet = Packet::parse(received_data).unwrap();
let upstream_packet = Packet::parse(&lbuf).unwrap();
recv_packet.header.query = true;
recv_packet.header.authoritative = false;
recv_packet.header.truncated = false;
recv_packet.header.recursion_avail = false;
recv_packet.header.reserved = 0;
recv_packet.header.rcode =
if recv_packet.header.opcode == 0 { 0 } else { 4 };
recv_packet.header.an_count = recv_packet.header.qd_count;
recv_packet.header.authority_records = 0;
recv_packet.header.additional_records = 0;
recv_packet.answers = upstream_packet.answers;
let mut response = vec![];
recv_packet.write_to(&mut response);
udp_socket
.send_to(&response, source)
.expect("Failed to send response");
}
Err(e) => {
eprintln!("error in receving data from upstream: {}", e);
continue 'outer;
}
}
recv_packet.write_to(&mut response);
udp_socket
.send_to(&response, source)
.expect("Failed to send response");
}
Err(e) => {
eprintln!("Error receiving data: {}", e);
@ -75,9 +92,6 @@ impl<'a> Packet<'a> {
for _ in 0..header.qd_count {
let rec = Question::parse(data, original)?;
println!("label = {}", rec.name);
data = &data[rec.length()..];
questions.push(rec);
}
@ -126,10 +140,16 @@ mod test {
0x7, 0x74, 0x65, 0x73, 0x74, 0x69, 0x6e, 0x67, 0xc0, 0xc, 0x00, 0x01, 0x00, 0x01,
];
let packet = Packet::parse(&data);
let packet = match Packet::parse(&data) {
Ok(v) => v,
Err(e) => {
panic!("failed to parse packet: {}", e);
}
};
assert!(packet.is_ok());
let mut buf = Vec::with_capacity(data.len());
packet.write_to(&mut buf);
println!("{:?}", packet);
assert_eq!(buf, data);
}
}

25
src/qname.rs
View File

@ -54,31 +54,6 @@ impl<'a> Qname<'a> {
pub fn length(&self) -> usize {
self.length
}
pub fn labels(&'a self) -> Vec<&'a [u8]> {
let mut lookup: &[u8] = &self.name;
let mut out = vec![];
let mut i = 0;
while i < lookup.len() - 1 && lookup[i + 1] != 0 {
let is_pointer = (lookup[i] & 0xc0) == 0xc0;
if is_pointer {
let offset: u16 = (((lookup[i] & !0xc0) as u16) << 8) | lookup[i + 1] as u16;
i = offset as usize;
lookup = &self.original;
} else {
let length = lookup[i] as usize;
out.push(&lookup[i + 1..i + length + 1]);
i += length + 1;
}
}
out
}
}
impl<'a> Display for Qname<'a> {