195 lines
9.0 KiB
C
195 lines
9.0 KiB
C
/*
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* dnstap/dnstap_fstrm.h - Frame Streams protocol for dnstap
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*
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* Copyright (c) 2020, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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/**
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* \file
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*
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* Definitions for the Frame Streams data transport protocol for
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* dnstap message logs.
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*/
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#ifndef DNSTAP_FSTRM_H
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#define DNSTAP_FSTRM_H
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/* Frame Streams data transfer protocol encode for DNSTAP messages.
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* The protocol looks to be specified in the libfstrm library.
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*
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* Quick writeup for DNSTAP usage, from reading fstrm/control.h eloquent
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* comments and fstrm/control.c for some bytesize details (the content type
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* length).
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*
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* The Frame Streams can be unidirectional or bi-directional.
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* bi-directional streams use control frame types READY, ACCEPT and FINISH.
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* uni-directional streams use control frame types START and STOP.
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* unknown control frame types should be ignored by the receiver, they
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* do not change the data frame encoding.
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*
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* bi-directional control frames implement a simple handshake protocol
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* between sender and receiver.
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*
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* The uni-directional control frames have one start and one stop frame,
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* before and after the data. The start frame can have a content type.
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* The start and stop frames are not optional.
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*
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* data frames are preceded by 4byte length, bigendian.
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* zero length data frames are not possible, they are an escape that
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* signals the presence of a control frame.
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*
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* a control frame consists of 0 value in 4byte bigendian, this is really
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* the data frame length, with 0 the escape sequence that indicates one
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* control frame follows.
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* Then, 4byte bigendian, length of the control frame message.
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* Then, the control frame payload (of that length). with in it:
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* 4byte bigendian, control type (eg. START, STOP, READY, ACCEPT, FINISH).
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* perhaps nothing more (STOP, FINISH), but for other types maybe
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* control fields
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* 4byte bigendian, the control-field-type, currently only content-type.
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* 4byte bigendian, length of the string for this option.
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* .. bytes of that string.
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*
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* The START type can have only one field. Field max len 256.
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* control frame max frame length 512 (excludes the 0-escape and control
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* frame length bytes).
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*
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* the bidirectional type of transmission is like this:
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* client sends READY (with content type included),
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* client waits for ACCEPT (with content type included),
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* client sends START (with matched content type from ACCEPT)
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* .. data frames
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* client sends STOP.
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* client waits for FINISH frame.
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*
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*/
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/** max length of Frame Streams content type field string */
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#define FSTRM_CONTENT_TYPE_LENGTH_MAX 256
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/** control frame value to denote the control frame ACCEPT */
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#define FSTRM_CONTROL_FRAME_ACCEPT 0x01
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/** control frame value to denote the control frame START */
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#define FSTRM_CONTROL_FRAME_START 0x02
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/** control frame value to denote the control frame STOP */
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#define FSTRM_CONTROL_FRAME_STOP 0x03
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/** control frame value to denote the control frame READY */
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#define FSTRM_CONTROL_FRAME_READY 0x04
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/** control frame value to denote the control frame FINISH */
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#define FSTRM_CONTROL_FRAME_FINISH 0x05
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/** the constant that denotes the control field type that is the
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* string for the content type of the stream. */
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#define FSTRM_CONTROL_FIELD_TYPE_CONTENT_TYPE 0x01
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/** the content type for DNSTAP frame streams */
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#define DNSTAP_CONTENT_TYPE "protobuf:dnstap.Dnstap"
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/**
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* This creates an FSTRM control frame of type START.
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* @param contenttype: a zero delimited string with the content type.
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* eg. use the constant DNSTAP_CONTENT_TYPE, which is defined as
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* "protobuf:dnstap.Dnstap", for a dnstap frame stream.
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* @param len: if a buffer is returned this is the length of that buffer.
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* @return NULL on malloc failure. Returns a malloced buffer with the
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* protocol message. The buffer starts with the 4 bytes of 0 that indicate
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* a control frame. The buffer should be sent without preceding it with
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* the 'len' variable (like data frames are), but straight the content of the
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* buffer, because the lengths are included in the buffer. This is so that
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* the zero control indicator can be included before the control frame length.
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*/
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void* fstrm_create_control_frame_start(char* contenttype, size_t* len);
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/**
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* This creates an FSTRM control frame of type READY.
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* @param contenttype: a zero delimited string with the content type.
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* eg. use the constant DNSTAP_CONTENT_TYPE, which is defined as
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* "protobuf:dnstap.Dnstap", for a dnstap frame stream.
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* @param len: if a buffer is returned this is the length of that buffer.
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* @return NULL on malloc failure. Returns a malloced buffer with the
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* protocol message. The buffer starts with the 4 bytes of 0 that indicate
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* a control frame. The buffer should be sent without preceding it with
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* the 'len' variable (like data frames are), but straight the content of the
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* buffer, because the lengths are included in the buffer. This is so that
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* the zero control indicator can be included before the control frame length.
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*/
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void* fstrm_create_control_frame_ready(char* contenttype, size_t* len);
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/**
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* This creates an FSTRM control frame of type STOP.
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* @param len: if a buffer is returned this is the length of that buffer.
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* @return NULL on malloc failure. Returns a malloced buffer with the
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* protocol message. The buffer starts with the 4 bytes of 0 that indicate
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* a control frame. The buffer should be sent without preceding it with
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* the 'len' variable (like data frames are), but straight the content of the
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* buffer, because the lengths are included in the buffer. This is so that
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* the zero control indicator can be included before the control frame length.
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*/
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void* fstrm_create_control_frame_stop(size_t* len);
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/**
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* This creates an FSTRM control frame of type ACCEPT.
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* @param contenttype: a zero delimited string with the content type.
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* for dnstap streams use DNSTAP_CONTENT_TYPE.
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* @param len: if a buffer is returned this is the length of that buffer.
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* @return NULL on malloc failure. Returns a malloced buffer with the
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* protocol message. The buffer starts with the 4 bytes of 0 that indicate
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* a control frame. The buffer should be sent without preceding it with
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* the 'len' variable (like data frames are), but straight the content of the
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* buffer, because the lengths are included in the buffer. This is so that
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* the zero control indicator can be included before the control frame length.
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*/
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void* fstrm_create_control_frame_accept(char* contenttype, size_t* len);
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/**
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* This creates an FSTRM control frame of type FINISH.
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* @param len: if a buffer is returned this is the length of that buffer.
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* @return NULL on malloc failure. Returns a malloced buffer with the
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* protocol message. The buffer starts with the 4 bytes of 0 that indicate
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* a control frame. The buffer should be sent without preceding it with
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* the 'len' variable (like data frames are), but straight the content of the
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* buffer, because the lengths are included in the buffer. This is so that
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* the zero control indicator can be included before the control frame length.
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*/
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void* fstrm_create_control_frame_finish(size_t* len);
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/**
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* Return string that describes a control packet. For debug, logs.
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* Like 'start content-type(protobuf:dnstap.Dnstap)' or 'stop'.
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* @param pkt: the packet data, that is the data after the 4 zero start
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* bytes and 4 length bytes.
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* @param len: the length of the control packet data, in pkt. This is the
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* ntohl of the 4 bytes length preceding the data.
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* @return zero delimited string, malloced. Or NULL on malloc failure.
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*/
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char* fstrm_describe_control(void* pkt, size_t len);
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#endif /* DNSTAP_FSTRM_H */
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