Ignore retries of the same DNS query

src/main.rs

@@ -19,6 +19,7 @@ struct OrigPacket {
  qname: String,
  typ: String,
  server_ip: String,
+ server_port: u16,
  report: bool,
 }
 
@@ -142,6 +143,11 @@ fn print_packet(
  IpHeader::Version4(x) => (x.source.into(), x.destination.into()),
  IpHeader::Version6(x) => (x.source.into(), x.destination.into()),
  };
+ let udp_header = packet
+ .transport
+ .expect("Error: Expected transport header")
+ .udp()
+ .expect("Error: Expected UDP packet");
  // Parse DNS data
  let dns_packet = DNSPacket::parse(packet.payload).wrap_err("Failed to parse DNS packet")?;
  let question = &dns_packet.questions[0];
@@ -154,11 +160,19 @@ fn print_packet(
  typ: format!("{:?}", question.qtype),
  qname: question.qname.to_string(),
  server_ip: format!("{}", dest_ip),
+ server_port: udp_header.destination_port,
  report: false,
  },
  );
  return Ok(());
  }
+ let orig_packet = map.get(&id).unwrap(); // this unwrap() is ok because we know it's in the map
+ if (format!("{}", src_ip).as_str(), udp_header.source_port)
+ != (orig_packet.server_ip.as_str(), orig_packet.server_port)
+ {
+ // This packet isn't a response to the original packet, so we ignore it -- it's just a retry
+ return Ok(());
+ }
  // If it's the second time we're seeing it, it's a response, so remove it from the map
  map.remove(&id);
  // Format the response data