nghttpx: Extend QUIC server ID to 4 bytes

doc/sources/nghttpx-howto.rst

@@ -544,10 +544,10 @@ Algorithm described in `QUIC-LB draft
 <https://datatracker.ietf.org/doc/html/draft-ietf-quic-load-balancers>`_.
 A Connection ID that nghttpx generates is always 20 bytes long.  It
 uses first 2 bits as a configuration ID.  The remaining bits in the
-first byte are reserved and random.  The next 2 bytes are server ID.
-The next 6 bytes are used to route UDP datagram to a correct
+first byte are reserved and random.  The next 4 bytes are server ID.
+The next 4 bytes are used to route UDP datagram to a correct
 ``SO_REUSEPORT`` socket.  The remaining bytes are randomly generated.
-The server ID and the next 14 bytes are encrypted with AES-ECB.  The
+The server ID and the next 12 bytes are encrypted with AES-ECB.  The
 key is derived from the keying materials stored in a file specified by
 :option:`--frontend-quic-secret-file`.  The first 2 bits of keying
 material in the file is used as a configuration ID.  The remaining

src/shrpx.cc

@@ -3395,8 +3395,8 @@ HTTP/3 and QUIC:
               Specify server  ID encoded in Connection  ID to identify
               this  particular  server  instance.   Connection  ID  is
               encrypted and  this part is  not visible in  public.  It
-              must be 2  bytes long and must be encoded  in hex string
-              (which is 4  bytes long).  If this option  is omitted, a
+              must be 4  bytes long and must be encoded  in hex string
+              (which is 8  bytes long).  If this option  is omitted, a
               random   server  ID   is   generated   on  startup   and
               configuration reload.
   --no-quic-bpf

src/shrpx_quic.h

@@ -64,7 +64,7 @@ struct QUICKeyingMaterials;
 struct QUICKeyingMaterial;
 
 constexpr size_t SHRPX_QUIC_SCIDLEN = 20;
-constexpr size_t SHRPX_QUIC_SERVER_IDLEN = 2;
+constexpr size_t SHRPX_QUIC_SERVER_IDLEN = 4;
 // SHRPX_QUIC_CID_PREFIXLEN includes SHRPX_QUIC_SERVER_IDLEN.
 constexpr size_t SHRPX_QUIC_CID_PREFIXLEN = 8;
 constexpr size_t SHRPX_QUIC_CID_PREFIX_OFFSET = 1;