Remove the Packet Format flag.

We should not leak the packet format information. The packet
format can be still identified by checking the first nibble
of the payload.

Author: klassert

eesp.org

@@ -208,7 +208,7 @@ The fixed portion of the base header is defined as follows.
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-   |1|Version|Flags|    Opt Len    |         Session ID            |
+   |1|Version|  R  |    Opt Len    |         Session ID            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                              SPI                              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
@@ -226,7 +226,9 @@ The fixed portion of the base header is defined as follows.
   necessarily able to parse the packet correctly. Intermediate
   treatment of such packets is policy-dependent (e.g., it may dictate
   dropping such packets).
-- Flags :: 3 bits: The Flags field is used as specified in [[flags]].
+- Reserved (R) :: 3 bits: Reserved for future versions, MUST be set to zero
+  and checked by the receiver. If the reserved bits are different to zero,
+  the packet MUST be dropped by the receiver.
 - Opt Len :: 8 bits: Length in bytes of the ~Options~ field.
 - Session ID :: 16 bits: The Session ID covers additional information
   that might be used to identify the SA.
@@ -237,27 +239,10 @@ The fixed portion of the base header is defined as follows.
 - Security Parameter Index (SPI) :: 32 bits: The SPI is an arbitrary
   32-bit value that is used by a receiver to identify the SA to which
   an incoming packet is bound.
+
 # XXX: Enhanced SPI is not explained!
 # This combined with the 16-bit Session ID is the Enhanced SPI.
 
-The Flags field in the fixed Base Header is defined as follows:
-
-#+caption: Base Header Flags
-#+name: flags
-#+begin_src
-    0 1 2
-   +-+-+-+
-   |F|R R|
-   +-+-+-+
-#+end_src
-
-- Packet Format (F) :: 1 bit: Set to zero for full EESP packet Format (i.e., the EESP header includes the
-  ~Payload Info Header~), set to 1 for Optimized EESP Packet format.
-- Reserved (RR) :: 2 bits: Reserved for future versions, MUST be set to 00,
-  and ignored by the receiver.
-
-
-
 # Note STK: Discuss Enhanced SPI here later...
 
 *** Base Header Options