FIX: Servers should drop received DNS response messages, not propagat…

…e them for processing. (#381)
NLnetLabs · Oct 3, 2024 · 930786e · 930786e
1 parent 1c7be5d
commit 930786e
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Showing 2 changed files with 22 additions and 1 deletion.
diff --git a/src/net/server/connection.rs b/src/net/server/connection.rs
@@ -670,6 +670,7 @@ where
 
                 match Message::from_octets(buf) {
                     Err(err) => {
+                        // TO DO: Count this event?
                         tracing::warn!(
                             "Failed while parsing request message: {err}"
                         );
@@ -678,6 +679,15 @@ where
                         ));
                     }
 
+                    // https://datatracker.ietf.org/doc/html/rfc1035#section-4.1.1
+                    // 4.1.1. Header section format
+                    //   "QR   A one bit field that specifies whether this
+                    //         message is a query (0), or a response (1)."
+                    Ok(msg) if msg.header().qr() => {
+                        // TO DO: Count this event?
+                        trace!("Ignoring received message because it is a reply, not a query.");
+                    }
+
                     Ok(msg) => {
                         let ctx = NonUdpTransportContext::new(Some(
                             self.config.load().idle_timeout,

diff --git a/src/net/server/dgram.rs b/src/net/server/dgram.rs
@@ -511,7 +511,18 @@ where
                     tokio::spawn(async move {
                         match Message::from_octets(buf) {
                             Err(err) => {
-                                tracing::warn!("Failed while parsing request message: {err}");
+                                // TO DO: Count this event?
+                                warn!("Failed while parsing request message: {err}");
+                            }
+
+                            // https://datatracker.ietf.org/doc/html/rfc1035#section-4.1.1
+                            // 4.1.1. Header section format
+                            //   "QR   A one bit field that specifies whether
+                            //         this message is a query (0), or a
+                            //         response (1)."
+                            Ok(msg) if msg.header().qr() => {
+                                // TO DO: Count this event?
+                                trace!("Ignoring received message because it is a reply, not a query.");
                             }
 
                             Ok(msg) => {