QUIC CONFORMANCE: Enforce minimal frame type encoding

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21135)

2 files changed, 17 insertions, 4 deletions

diff --git a/include/internal/packet_quic.h b/include/internal/packet_quic.h
index 7784e62c16..e75b81e422 100644
--- a/include/internal/packet_quic.h
+++ b/include/internal/packet_quic.h
@@ -40,10 +40,12 @@ __owur static ossl_inline int PACKET_get_quic_vlint(PACKET *pkt,
 /*
  * Decodes a QUIC variable-length integer in |pkt| and stores the result in
  * |data|. Unlike PACKET_get_quic_vlint, this does not advance the current
- * position.
+ * position. If was_minimal is non-NULL, *was_minimal is set to 1 if the integer
+ * was encoded using the minimal possible number of bytes and 0 otherwise.
  */
-__owur static ossl_inline int PACKET_peek_quic_vlint(PACKET *pkt,
-                                                     uint64_t *data)
+__owur static ossl_inline int PACKET_peek_quic_vlint_ex(PACKET *pkt,
+                                                        uint64_t *data,
+                                                        int *was_minimal)
 {
     size_t enclen;
 
@@ -56,9 +58,19 @@ __owur static ossl_inline int PACKET_peek_quic_vlint(PACKET *pkt,
         return 0;
 
     *data = ossl_quic_vlint_decode_unchecked(pkt->curr);
+
+    if (was_minimal != NULL)
+        *was_minimal = (enclen == ossl_quic_vlint_encode_len(*data));
+
     return 1;
 }
 
+__owur static ossl_inline int PACKET_peek_quic_vlint(PACKET *pkt,
+                                                     uint64_t *data)
+{
+    return PACKET_peek_quic_vlint_ex(pkt, data, NULL);
+}
+
 /*
  * Skips over a QUIC variable-length integer in |pkt| without decoding it.
  */
diff --git a/include/internal/quic_wire.h b/include/internal/quic_wire.h
index e9ff8e6f35..8a1ef34ead 100644
--- a/include/internal/quic_wire.h
+++ b/include/internal/quic_wire.h
@@ -493,7 +493,8 @@ int ossl_quic_wire_encode_transport_param_cid(WPACKET *wpkt,
  * position). This can be used to determine the frame type and determine which
  * frame decoding function to call.
  */
-int ossl_quic_wire_peek_frame_header(PACKET *pkt, uint64_t *type);
+int ossl_quic_wire_peek_frame_header(PACKET *pkt, uint64_t *type,
+                                     int *was_minimal);
 
 /*
  * Like ossl_quic_wire_peek_frame_header, but advances the current position