Fix checking packet header under disable_1rtt_encryption mode (#413)

Author: iyangsj

.github/workflows/tquic-integration.yml

@@ -23,3 +23,7 @@ jobs:
       run: |
         cd tools/tests/
         bash ./tquic_tools_test.sh -b ../../target/release/ -t multipath_redundant,multipath_minrtt,multipath_roundrobin -f 1000M -p 5
+    - name: Run integration tests for disable_1rtt_encryption
+      run: |
+        cd tools/tests/
+        bash ./tquic_tools_test.sh -b ../../target/release/ -t multipath_minrtt -c '~~disable-encryption' -s '~~disable-encryption'

src/connection/connection.rs

@@ -1680,7 +1680,11 @@ impl Connection {
             .tls_session
             .get_overhead(level)
             .ok_or(Error::InternalError)?;
-        let total_overhead = pkt_num_offset + pkt_num_len + crypto_overhead;
+        let total_overhead = if !self.is_encryption_disabled(hdr.pkt_type) {
+            pkt_num_offset + pkt_num_len + crypto_overhead
+        } else {
+            pkt_num_offset + pkt_num_len
+        };
 
         match left.checked_sub(total_overhead) {
             Some(val) => left = val,
@@ -1727,6 +1731,8 @@ impl Connection {
         // fields) in bytes
         let payload_len = write_status.written;
         if pkt_type != PacketType::OneRTT {
+            // Note: This type of packet is always encrypted, even if the disable_1rtt_encryption
+            // transport parameter is successfully negotiated.
             let len = pkt_num_len + payload_len + crypto_overhead;
             let mut out = &mut out[hdr_offset..];
             out.write_varint_with_len(len as u64, crate::LENGTH_FIELD_LEN)?;

src/packet.rs

@@ -541,33 +541,43 @@ pub(crate) fn decrypt_header(
     aead: &Open,
     plaintext_mode: bool,
 ) -> Result<()> {
-    if pkt_buf.len() < pkt_num_offset + MAX_PKT_NUM_LEN + SAMPLE_LEN {
+    let pkt_buf_min = if !plaintext_mode {
+        pkt_num_offset + MAX_PKT_NUM_LEN + SAMPLE_LEN
+    } else {
+        // All aspects of encryption on 1-RTT packets are removed and it is no
+        // longer including an AEAD tag.
+        pkt_num_offset + MAX_PKT_NUM_LEN
+    };
+    if pkt_buf.len() < pkt_buf_min {
         return Err(Error::BufferTooShort);
     }
 
+    // Decrypt packet haader if needed
     let mut first = pkt_buf[0];
-    let sample_start = pkt_num_offset + MAX_PKT_NUM_LEN;
-    let sample = &pkt_buf[sample_start..sample_start + SAMPLE_LEN];
-    let mask = aead.new_mask(sample)?;
-
-    // Remove protection of bits in the first byte
-    if !plaintext_mode {
+    let (pkt_num_len, pkt_num_buf) = if !plaintext_mode {
+        // Remove protection of bits in the first byte
+        let sample_start = pkt_num_offset + MAX_PKT_NUM_LEN;
+        let sample = &pkt_buf[sample_start..sample_start + SAMPLE_LEN];
+        let mask = aead.new_mask(sample)?;
         if PacketHeader::long_header(first) {
             first ^= mask[0] & 0x0f;
         } else {
             first ^= mask[0] & 0x1f;
         }
-    }
 
-    let pkt_num_len = usize::from((first & PKT_NUM_LEN_MASK) + 1);
-    let pkt_num_buf = &mut pkt_buf[pkt_num_offset..pkt_num_offset + pkt_num_len];
+        let pkt_num_len = usize::from((first & PKT_NUM_LEN_MASK) + 1);
+        let pkt_num_buf = &mut pkt_buf[pkt_num_offset..pkt_num_offset + pkt_num_len];
 
-    // Remove protection of packet number field
-    if !plaintext_mode {
+        // Remove protection of packet number field
         for i in 0..pkt_num_len {
             pkt_num_buf[i] ^= mask[i + 1];
         }
-    }
+        (pkt_num_len, pkt_num_buf)
+    } else {
+        let pkt_num_len = usize::from((first & PKT_NUM_LEN_MASK) + 1);
+        let pkt_num_buf = &mut pkt_buf[pkt_num_offset..pkt_num_offset + pkt_num_len];
+        (pkt_num_len, pkt_num_buf)
+    };
 
     // Extract packet number corresponding to the length.
     let pkt_num = {