NFD local control header¶

NFD local control header can be used between application and local forwarding daemon to exchange various NFD-specific local information that is not part of Interest and Data packet.
For example, the control header allows applications to request bypassing the Interest forwarding strategy by directly specify FaceId to which the Interest should be forwarded.

NFD local control header is not enabled by default and requires explicit request from the client to enable.
This request is in form of Signed Interest and have the following structure:

/localhost/nfd/control-header/<command-verb>/<timestamp>/<SignatureInfo>/<SignatureValue>

\                            / \           / \                                          /
 ------------  ------------     ----  -----   --------------------  --------------------
             \/                     \/                            \/
   NFD Control Command         "enable" or       Signed Interest related information
                                "disable"

LocalControlHeader¶

If command to enable LocalControlHeader is authorized by NFD, all subsequent communication from NFD will include LocalControlHeader as defined below.
The authorized application will also be able to include LocalControlHeader in communication to NFD---until specifically enabled, all specified LocalControlHeaders should be ignored by NFD.

LocalControlHeader ::= LOCAL-CONTROL-HEADER-TYPE TLV-LENGTH
                         LocalControlInfo
                         (Interest | Data)

LocalControlInfo   ::= LOCAL-CONTROL-INFO-TYPE TLV-LENGTH
                         (IncomingFaceId |
                          OutgoingFaceId |
                          TapInfo)

IncomingFaceId     ::= INCOMING-FACE-ID-TYPE TLV-LENGTH
                          nonNegativeInteger

OutgoingFaceId     ::= INCOMING-FACE-ID-TYPE TLV-LENGTH
                          nonNegativeInteger

TapInfo            ::= TAP-INFO-TYPE TLV-LENGTH
                         ...
                         (TBD)

TLV-TYPE assignments¶