MINOR: quic: Ignore out of packet padding.

We do not want to count the out of packet padding as being belonging
to an invalid packet, the firt byte of a QUIC packet being never null.
Some browsers like firefox proceeds this way to add PADDING frames
after an Initial packet and increase the size of their Initial packets.

diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 41d7ef6c4ef8eba6e1c6c6d2442e8dc0558c2046..60051d83852553ffacc886cc37c9cb6cb697660f 100644 (file)
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -5152,6 +5152,20 @@ static int qc_conn_alloc_ssl_ctx(struct quic_conn *qc)
        return 1;
 }
 
+/* Check that all the bytes between <buf> included and <end> address
+ * excluded are null. This is the responsability of the caller to
+ * check that there is at least one byte between <buf> end <end>.
+ * Return 1 if this all the bytes are null, 0 if not.
+ */
+static inline int quic_padding_check(const unsigned char *buf,
+                                     const unsigned char *end)
+{
+       while (buf < end && !*buf)
+               buf++;
+
+       return buf == end;
+}
+
 /* Parse a QUIC packet from UDP datagram found in <buf> buffer with <end> the
  * end of this buffer past one byte and populate <pkt> RX packet structure
  * with the information collected from the packet.
@@ -5195,7 +5209,16 @@ static void qc_lstnr_pkt_rcv(unsigned char *buf, const unsigned char *end,
 
        /* Fixed bit */
        if (!(*buf & QUIC_PACKET_FIXED_BIT)) {
-               /* XXX TO BE DISCARDED */
+               if (!first_pkt && quic_padding_check(buf, end)) {
+                       /* Some browsers may pad the remaining datagram space with null bytes.
+                        * That is what we called add padding out of QUIC packets. Such
+                        * datagrams must be considered as valid. But we can only consume
+                        * the remaining space.
+                        */
+                       pkt->len = end - buf;
+                       goto drop_no_conn;
+               }
+
                TRACE_PROTO("Packet dropped", QUIC_EV_CONN_LPKT);
                goto drop;
        }