unbound/dnstap/dnstap_fstrm.h

195 lines
9.0 KiB
C

/*
* dnstap/dnstap_fstrm.h - Frame Streams protocol for dnstap
*
* Copyright (c) 2020, NLnet Labs. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the NLNET LABS nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/**
* \file
*
* Definitions for the Frame Streams data transport protocol for
* dnstap message logs.
*/
#ifndef DNSTAP_FSTRM_H
#define DNSTAP_FSTRM_H
/* 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
* control 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).
*
* the bidirectional type of transmission is like this:
* client sends READY (with content type included),
* client waits for ACCEPT (with content type included),
* client sends START (with matched content type from ACCEPT)
* .. data frames
* client sends STOP.
* client waits for FINISH frame.
*
*/
/** 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
/** the content type for DNSTAP frame streams */
#define DNSTAP_CONTENT_TYPE "protobuf:dnstap.Dnstap"
/**
* This creates an FSTRM control frame of type START.
* @param contenttype: a zero delimited string with the content type.
* eg. use the constant DNSTAP_CONTENT_TYPE, which is defined as
* "protobuf:dnstap.Dnstap", for a dnstap frame stream.
* @param len: if a buffer is returned this is the length of that buffer.
* @return NULL on malloc failure. Returns a malloced buffer with the
* protocol message. The buffer starts with the 4 bytes of 0 that indicate
* a control frame. The buffer should be sent without preceding it with
* the 'len' variable (like data frames are), but straight the content of the
* buffer, because the lengths are included in the buffer. This is so that
* the zero control indicator can be included before the control frame length.
*/
void* fstrm_create_control_frame_start(char* contenttype, size_t* len);
/**
* This creates an FSTRM control frame of type READY.
* @param contenttype: a zero delimited string with the content type.
* eg. use the constant DNSTAP_CONTENT_TYPE, which is defined as
* "protobuf:dnstap.Dnstap", for a dnstap frame stream.
* @param len: if a buffer is returned this is the length of that buffer.
* @return NULL on malloc failure. Returns a malloced buffer with the
* protocol message. The buffer starts with the 4 bytes of 0 that indicate
* a control frame. The buffer should be sent without preceding it with
* the 'len' variable (like data frames are), but straight the content of the
* buffer, because the lengths are included in the buffer. This is so that
* the zero control indicator can be included before the control frame length.
*/
void* fstrm_create_control_frame_ready(char* contenttype, size_t* len);
/**
* This creates an FSTRM control frame of type STOP.
* @param len: if a buffer is returned this is the length of that buffer.
* @return NULL on malloc failure. Returns a malloced buffer with the
* protocol message. The buffer starts with the 4 bytes of 0 that indicate
* a control frame. The buffer should be sent without preceding it with
* the 'len' variable (like data frames are), but straight the content of the
* buffer, because the lengths are included in the buffer. This is so that
* the zero control indicator can be included before the control frame length.
*/
void* fstrm_create_control_frame_stop(size_t* len);
/**
* This creates an FSTRM control frame of type ACCEPT.
* @param contenttype: a zero delimited string with the content type.
* for dnstap streams use DNSTAP_CONTENT_TYPE.
* @param len: if a buffer is returned this is the length of that buffer.
* @return NULL on malloc failure. Returns a malloced buffer with the
* protocol message. The buffer starts with the 4 bytes of 0 that indicate
* a control frame. The buffer should be sent without preceding it with
* the 'len' variable (like data frames are), but straight the content of the
* buffer, because the lengths are included in the buffer. This is so that
* the zero control indicator can be included before the control frame length.
*/
void* fstrm_create_control_frame_accept(char* contenttype, size_t* len);
/**
* This creates an FSTRM control frame of type FINISH.
* @param len: if a buffer is returned this is the length of that buffer.
* @return NULL on malloc failure. Returns a malloced buffer with the
* protocol message. The buffer starts with the 4 bytes of 0 that indicate
* a control frame. The buffer should be sent without preceding it with
* the 'len' variable (like data frames are), but straight the content of the
* buffer, because the lengths are included in the buffer. This is so that
* the zero control indicator can be included before the control frame length.
*/
void* fstrm_create_control_frame_finish(size_t* len);
/**
* Return string that describes a control packet. For debug, logs.
* Like 'start content-type(protobuf:dnstap.Dnstap)' or 'stop'.
* @param pkt: the packet data, that is the data after the 4 zero start
* bytes and 4 length bytes.
* @param len: the length of the control packet data, in pkt. This is the
* ntohl of the 4 bytes length preceding the data.
* @return zero delimited string, malloced. Or NULL on malloc failure.
*/
char* fstrm_describe_control(void* pkt, size_t len);
#endif /* DNSTAP_FSTRM_H */