debug: dns proxy

src/header.rs

@@ -1,4 +1,4 @@
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct Header {
     pub ident: u16,
     pub query: bool,

src/main.rs

@@ -10,7 +10,7 @@ use std::net::{SocketAddr, UdpSocket};
 
 fn main() {
     let args: Vec<String> = std::env::args().collect();
-    let resolver: SocketAddr = args[2].parse().unwrap();
+    let resolver: SocketAddr = args[2].parse().expect("resolver address not provided");
 
     println!("resolver = {:?}", resolver);
 
@@ -19,55 +19,75 @@ fn main() {
     let udp_socket = UdpSocket::bind("127.0.0.1:2053").expect("Failed to bind to address");
     let mut buf = [0; 512];
 
-    'outer: loop {
+    loop {
         match udp_socket.recv_from(&mut buf) {
             Ok((size, source)) => {
                 println!("Received {} bytes from {}", size, source);
                 let received_data = &buf[0..size];
+                let mut recv_packet = Packet::parse(received_data).unwrap();
 
-                println!("{:0x?}", received_data);
+                for question in recv_packet.questions.iter() {
+                    let mut packet = recv_packet.clone();
+                    packet.header.qd_count = 1;
+                    packet.questions = vec![question.clone()];
 
-                upstream_socket
-                    .send_to(received_data, resolver)
-                    .expect("error in sending data to upstream");
+                    let mut data = vec![];
+                    packet.write_to(&mut data);
 
-                let mut lbuf = [0; 512];
+                    upstream_socket
+                        .send_to(&data, resolver)
+                        .expect("error in sending data to upstream");
+                }
+                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
-                        );
+                let mut responses = vec![[0; 512]; recv_packet.header.qd_count as usize];
+                let mut upstream_packets = vec![None; recv_packet.header.qd_count as usize];
 
-                        let mut recv_packet = Packet::parse(received_data).unwrap();
-                        let upstream_packet = Packet::parse(&lbuf).unwrap();
+                for (lbuf, packet) in responses.iter_mut().zip(upstream_packets.iter_mut()) {
+                    match upstream_socket.recv_from(lbuf) {
+                        Ok((size, upstream)) => {
+                            println!(
+                                "Received {}bytes from {} on upstream socket",
+                                size, upstream
+                            );
 
-                        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 = upstream_packet.header.an_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;
+                            *packet = Packet::parse(lbuf).ok();
+                        }
+                        Err(e) => {
+                            eprintln!("error in receiving data from upstream: {}", e);
+                        }
                     }
                 }
+
+                recv_packet.answers = upstream_packets
+                    .into_iter()
+                    .filter(|x| x.is_some())
+                    .flat_map(|packet| {
+                        if let Some(packet) = packet {
+                            if packet.answers.is_empty() {
+                                return None;
+                            }
+                            Some(packet.answers[0].clone())
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
+
+                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 receiving data: {}", e);
@@ -77,7 +97,7 @@ fn main() {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 struct Packet<'a> {
     header: Header,
     questions: Vec<Question<'a>>,

src/question.rs

@@ -1,6 +1,6 @@
 use crate::qname::Qname;
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct Question<'a> {
     pub name: Qname<'a>,
     pub q_type: u16,

src/rrecord.rs

@@ -1,6 +1,6 @@
 use crate::qname::Qname;
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct RRecord<'a> {
     pub name: Qname<'a>,
     pub r_type: u16,
@@ -60,17 +60,15 @@ impl<'a> RRecord<'a> {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum RData {
     A([u8; 4]),
-    Aaaa([u8; 16]),
 }
 
 impl RData {
     pub fn write_to(self, buf: &mut Vec<u8>) {
         match self {
             RData::A(addr) => buf.extend(addr),
-            RData::Aaaa(addr) => buf.extend(addr),
         }
     }
 }