This commit implements the generic process step to DCCPOptions

Implements the following point of the RFC 4340

5.8.  Options

   Any DCCP packet may contain options, which occupy space at the end of
   the DCCP header.  Each option is a multiple of 8 bits in length.
   Individual options are not padded to multiples of 32 bits, and any
   option may begin on any byte boundary.  However, the combination of
   all options MUST add up to a multiple of 32 bits; Padding options
   MUST be added as necessary to fill out option space to a word
   boundary.  Any options present are included in the header checksum.

   The first byte of an option is the option type.  Options with types 0
   through 31 are single-byte options.  Other options are followed by a
   byte indicating the option's length.  This length value includes the
   two bytes of option-type and option-length as well as any option-data
   bytes; it must therefore be greater than or equal to two.

   Options MUST be processed sequentially, starting with the first
   option in the packet header.  Options with unknown types MUST be

   ignored.  Also, options with nonsensical lengths (length byte less
   than two or more than the remaining space in the options portion of
   the header) MUST be ignored, and any option space following an option
   with nonsensical length MUST likewise be ignored.  Unless otherwise
   specified, multiple occurrences of the same option MUST be processed
   independently; for some options, this will mean in practice that the
   last valid occurrence of an option takes precedence.

   The following options are currently defined:

               Option                           DCCP-  Section
       Type    Length     Meaning               Data?  Reference
       ----    ------     -------               -----  ---------
         0        1       Padding                 Y      5.8.1
         1        1       Mandatory               N      5.8.2
         2        1       Slow Receiver           Y      11.6
       3-31       1       Reserved
        32     variable   Change L                N      6.1
        33     variable   Confirm L               N      6.2
        34     variable   Change R                N      6.1
        35     variable   Confirm R               N      6.2
        36     variable   Init Cookie             N      8.1.4
        37       3-8      NDP Count               Y      7.7
        38     variable   Ack Vector [Nonce 0]    N      11.4
        39     variable   Ack Vector [Nonce 1]    N      11.4
        40     variable   Data Dropped            N      11.7
        41        6       Timestamp               Y      13.1
        42      6/8/10    Timestamp Echo          Y      13.3
        43       4/6      Elapsed Time            N      13.2
        44        6       Data Checksum           Y      9.3
       45-127  variable   Reserved
      128-255  variable   CCID-specific options   -      10.3

                        Table 3: DCCP Options

   Not all options are suitable for all packet types.  For example,
   since the Ack Vector option is interpreted relative to the
   Acknowledgement Number, it isn't suitable on DCCP-Request and DCCP-
   Data packets, which have no Acknowledgement Number.  If an option
   occurs on an unexpected packet type, it MUST generally be ignored;
   any such restrictions are mentioned in each option's description.
   The table summarizes the most common restriction: when the DCCP-
   Data? column value is N, the corresponding option MUST be ignored
   when received on a DCCP-Data packet.  (Section 7.5.5 describes why
   such options are ignored as opposed to, say, causing a reset.)

   Options with invalid values MUST be ignored unless otherwise
   specified.  For example, any Data Checksum option with option length

   4 MUST be ignored, since all valid Data Checksum options have option
   length 6.

   This section describes two generic options, Padding and Mandatory.
   Other options are described later.

5.8.1.  Padding Option

   +--------+
   |00000000|
   +--------+
     Type=0

   Padding is a single-byte "no-operation" option used to pad between or
   after options.  If the length of a packet's other options is not a
   multiple of 32 bits, then Padding options are REQUIRED to pad out the
   options area to the length implied by Data Offset.  Padding may also
   be used between options; for example, to align the beginning of a
   subsequent option on a 32-bit boundary.  There is no guarantee that
   senders will use this option, so receivers must be prepared to
   process options even if they do not begin on a word boundary.

5.8.2.  Mandatory Option

   +--------+
   |00000001|
   +--------+
     Type=1

   Mandatory is a single-byte option that marks the immediately
   following option as mandatory.  Say that the immediately following
   option is O.  Then the Mandatory option has no effect if the
   receiving DCCP endpoint understands and processes O.  If the endpoint
   does not understand or process O, however, then it MUST reset the
   connection using Reset Code 6, "Mandatory Failure".  For instance,
   the endpoint would reset the connection if it did not understand O's
   type; if it understood O's type, but not O's data; if O's data was
   invalid for O's type; if O was a feature negotiation option, and the
   endpoint did not understand the enclosed feature number; or if the
   endpoint understood O, but chose not to perform the action O implies.
   This list is not exhaustive and, in particular, individual option
   specifications may describe additional situations in which the
   endpoint should reset the connection and situations in which it
   should not.

   Mandatory options MUST NOT be sent on DCCP-Data packets, and any
   Mandatory options received on DCCP-Data packets MUST be ignored.

   The connection is in error and should be reset with Reset Code 5,
   "Option Error", if option O is absent (Mandatory was the last byte of
   the option list), or if option O equals Mandatory.  However, the
   combination "Mandatory Padding" is valid, and MUST behave like two
   bytes of Padding.

Signed-off-by: Ivo Calado <txithihausen@gmail.com>