upstream/unbound
1
0
Fork 0
mirror of https://github.com/NLnetLabs/unbound.git synced 2025-12-27 10:10:09 -05:00
Code Issues Projects Releases Packages Wiki Activity Actions

Writeup of FrameStreams protocol.

Browse source
This commit is contained in:
W.C.A. Wijngaards 2020-01-20 11:44:45 +01:00
parent b7e08045b1
commit c6534ac6b3
1 changed files with 56 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

58
dnstap/dtstream.h
View file

@ -71,7 +71,7 @@ struct dt_msg_queue {
struct dt_msg_entry* first, *last;
};
/**
/**
* An entry in the dt_msg_queue. contains one DNSTAP message.
* It is malloced.
*/
@ -130,8 +130,62 @@ struct dt_io_thread {
/* Frame Streams data transfer protocol encode for DNSTAP messages.
* The protocol looks to be specified in the libfstrm library.
*
* Quick writeup for DNSTAP usage, from reading fstrm/control.h eloquent
* comments and fstrm/control.c for some bytesize details (the content type
* length).
*
* The Frame Streams can be unidirectional or bi-directional.
* bi-directional streams use control frame types READY, ACCEPT and FINISH.
* uni-directional streams use control frame types START and STOP.
* unknown control frame types should be ignored by the receiver, they
* do not change the data frame encoding.
*
* bi-directional control frames implement a simple handshake protocol
* between sender and receiver.
*
* The uni-directional control frames have one start and one stop frame,
* before and after the data. The start frame can have a content type.
* The start and stop frames are not optional.
*
* data frames are preceded by 4byte length, bigendian.
* zero length data frames are not possible, they are an escape that
* signals the presence of a control frame.
*
* a control frame consists of 0 value in 4byte bigendian, this is really
* the data frame length, with 0 the escape sequence that indicates one
* control frame follows.
* Then, 4byte bigendian, length of the control frame message.
* Then, the control frame payload (of that length). with in it:
* 4byte bigendian, control type (eg. START, STOP, READY, ACCEPT, FINISH).
* perhaps nothing more (STOP, FINISH), but for other types maybe
* content type fields
* 4byte bigendian, the control-field-type, currently only content-type.
* 4byte bigendian, length of the string for this option.
* .. bytes of that string.
*
* The START type can have only one field. Field max len 256.
* control frame max frame length 512 (excludes the 0-escape and control
* frame length bytes).
*/
/* routine to send START message. */
/** max length of Frame Streams content type field string */
#define FSTRM_CONTENT_TYPE_LENGTH_MAX 256
/** control frame value to denote the control frame ACCEPT */
#define FSTRM_CONTROL_FRAME_ACCEPT 0x01
/** control frame value to denote the control frame START */
#define FSTRM_CONTROL_FRAME_START 0x02
/** control frame value to denote the control frame STOP */
#define FSTRM_CONTROL_FRAME_STOP 0x03
/** control frame value to denote the control frame READY */
#define FSTRM_CONTROL_FRAME_READY 0x04
/** control frame value to denote the control frame FINISH */
#define FSTRM_CONTROL_FRAME_FINISH 0x05
/** the constant that denotes the control field type that is the
* string for the content type of the stream. */
#define FSTRM_CONTROL_FIELD_TYPE_CONTENT_TYPE 0x01
/* routine to send START message, with content type. */
/* routine to send a frame. */
/* routine to send STOP message. */