Truncate additional data

quinn-rs · Aug 25, 2020 · fe47254 · fe47254
1 parent b119819
commit fe47254
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Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/quinn-proto/src/lib.rs b/quinn-proto/src/lib.rs
@@ -235,3 +235,4 @@ const MIN_MTU: u16 = 1232;
 const TIMER_GRANULARITY: Duration = Duration::from_millis(1);
 /// Maximum number of streams that can be uniquely identified by a stream ID
 const MAX_STREAM_COUNT: u64 = 1 << 60;
+const MAX_ADDITIONAL_DATA_SIZE: usize = 39; // max(ipv4, ipv6) + port + retry_src_cid
diff --git a/quinn-proto/src/token.rs b/quinn-proto/src/token.rs
@@ -10,7 +10,7 @@ use crate::{
     coding::{BufExt, BufMutExt},
     crypto::{AeadKey, HmacKey, PseudoRandomKey},
     shared::ConnectionId,
-    RESET_TOKEN_SIZE,
+    MAX_ADDITIONAL_DATA_SIZE, RESET_TOKEN_SIZE,
 };
 
 // TODO: Use AEAD to hide token details from clients for better stability guarantees:
@@ -80,7 +80,7 @@ impl<'a> RetryToken<'a> {
         let aead_key = key.aead_from_hkdf(random_bytes);
         let mut sealed_token = raw_token_bytes[Self::RANDOM_BYTES_LEN..].to_vec();
 
-        let mut additional_data = [0u8; 16 + 2 + 21]; // max(ipv4, ipv6) + port + retry_src_cid
+        let mut additional_data = [0u8; MAX_ADDITIONAL_DATA_SIZE];
         let mut cursor = &mut additional_data[..];
         match address.ip() {
             IpAddr::V4(x) => cursor.put_slice(&x.octets()),
@@ -89,7 +89,8 @@ impl<'a> RetryToken<'a> {
         cursor.write(address.port());
         retry_src_cid.encode_long(&mut cursor);
 
-        let data = aead_key.open(&mut sealed_token, &additional_data)?;
+        let size = MAX_ADDITIONAL_DATA_SIZE - cursor.len();
+        let data = aead_key.open(&mut sealed_token, &additional_data[..size])?;
         let mut reader = io::Cursor::new(data);
 
         let orig_dst_cid = ConnectionId::decode_long(&mut reader).ok_or(())?;