Add WASM/JS support for doing full lookups using DoH

[dnssec-prover] / src / query.rs

diff --git a/src/query.rs b/src/query.rs
index c2ea75e4de7a9fe96b408c7f5bf1ea90ffbd6a8e..07954b3cb9fccc348803c00a5c229b20be1eca76 100644 (file)
--- a/src/query.rs
+++ b/src/query.rs
@@ -21,9 +21,9 @@ use crate::ser::*;
 // In testing use a rather small buffer to ensure we hit the allocation paths sometimes. In
 // production, we should generally never actually need to go to heap as DNS messages are rarely
 // larger than a KiB or two.
-#[cfg(test)]
+#[cfg(any(test, fuzzing))]
 const STACK_BUF_LIMIT: u16 = 32;
-#[cfg(not(test))]
+#[cfg(not(any(test, fuzzing)))]
 const STACK_BUF_LIMIT: u16 = 2048;
 
 /// A buffer for storing queries and responses.
@@ -34,7 +34,8 @@ pub struct QueryBuf {
        len: u16,
 }
 impl QueryBuf {
-       fn new_zeroed(len: u16) -> Self {
+       /// Generates a new buffer of the given length, consisting of all zeros.
+       pub fn new_zeroed(len: u16) -> Self {
                let heap_buf = if len > STACK_BUF_LIMIT { vec![0; len as usize] } else { Vec::new() };
                Self {
                        buf: [0; STACK_BUF_LIMIT as usize],
@@ -42,7 +43,11 @@ impl QueryBuf {
                        len
                }
        }
-       pub(crate) fn extend_from_slice(&mut self, sl: &[u8]) {
+       /// Extends the size of this buffer by appending the given slice.
+       ///
+       /// If the total length of this buffer exceeds [`u16::MAX`] after appending, the buffer's state
+       /// is undefined, however pushing data beyond [`u16::MAX`] will not panic.
+       pub fn extend_from_slice(&mut self, sl: &[u8]) {
                let new_len = self.len.saturating_add(sl.len() as u16);
                let was_heap = self.len > STACK_BUF_LIMIT;
                let is_heap = new_len > STACK_BUF_LIMIT;
@@ -59,6 +64,14 @@ impl QueryBuf {
                target.copy_from_slice(sl);
                self.len = new_len;
        }
+       /// Converts this query into its bytes on the heap
+       pub fn into_vec(self) -> Vec<u8> {
+               if self.len > STACK_BUF_LIMIT {
+                       self.heap_buf
+               } else {
+                       self.buf[..self.len as usize].to_vec()
+               }
+       }
 }
 impl ops::Deref for QueryBuf {
        type Target = [u8];
@@ -80,14 +93,12 @@ impl ops::DerefMut for QueryBuf {
        }
 }
 
-// We don't care about transaction IDs as we're only going to accept signed data. Thus, we use
-// this constant instead of a random value.
-const TXID: u16 = 0x4242;
+// We don't care about transaction IDs as we're only going to accept signed data.
+// Further, if we're querying over DoH, the RFC says we SHOULD use a transaction ID of 0 here.
+const TXID: u16 = 0;
 
 fn build_query(domain: &Name, ty: u16) -> QueryBuf {
        let mut query = QueryBuf::new_zeroed(0);
-       let query_msg_len: u16 = 2 + 2 + 8 + 2 + 2 + name_len(domain) + 11;
-       query.extend_from_slice(&query_msg_len.to_be_bytes());
        query.extend_from_slice(&TXID.to_be_bytes());
        query.extend_from_slice(&[0x01, 0x20]); // Flags: Recursive, Authenticated Data
        query.extend_from_slice(&[0, 1, 0, 0, 0, 0, 0, 1]); // One question, One additional
@@ -147,6 +158,21 @@ fn handle_response(resp: &[u8], proof: &mut Vec<u8>, rrsig_key_names: &mut Vec<N
        Ok(min_ttl)
 }
 
+#[cfg(fuzzing)]
+/// Read a stream of responses and handle them it as if they came from a server, for fuzzing.
+pub fn fuzz_proof_builder(mut response_stream: &[u8]) {
+       let (mut builder, _) = ProofBuilder::new(&"example.com.".try_into().unwrap(), Txt::TYPE);
+       while builder.awaiting_responses() {
+               let len = if let Ok(len) = read_u16(&mut response_stream) { len } else { return };
+               let mut buf = QueryBuf::new_zeroed(len);
+               if response_stream.len() < len as usize { return; }
+               buf.copy_from_slice(&response_stream[..len as usize]);
+               response_stream = &response_stream[len as usize..];
+               let _ = builder.process_response(&buf);
+       }
+       let _ = builder.finish_proof();
+}
+
 const MAX_REQUESTS: usize = 10;
 /// A simple state machine which will generate a series of queries and process the responses until
 /// it has built a DNSSEC proof.
@@ -243,12 +269,14 @@ impl ProofBuilder {
 
 #[cfg(feature = "std")]
 fn send_query(stream: &mut TcpStream, query: &[u8]) -> Result<(), Error> {
+       stream.write_all(&(query.len() as u16).to_be_bytes())?;
        stream.write_all(&query)?;
        Ok(())
 }
 
 #[cfg(feature = "tokio")]
 async fn send_query_async(stream: &mut TokioTcpStream, query: &[u8]) -> Result<(), Error> {
+       stream.write_all(&(query.len() as u16).to_be_bytes()).await?;
        stream.write_all(&query).await?;
        Ok(())
 }