bacnet-stack/src/bacnet/bacdcode.c at master · bacnet-stack/bacnet-stack · GitHub

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/**

* @file

* @brief BACnet primitive data encode and decode helper functions

* @author Steve Karg <skarg@users.sourceforge.net>

* @date 2004

* @copyright SPDX-License-Identifier: GPL-2.0-or-later WITH GCC-exception-2.0

#include <string.h>

/* BACnet Stack defines - first */

#include "bacnet/bacdef.h"

/* BACnet Stack API */

#include "bacnet/bacdcode.h"

#include "bacnet/bacstr.h"

#include "bacnet/bacint.h"

#include "bacnet/bacreal.h"

#include "bacnet/basic/sys/compare.h"

/* max-segments-accepted

B'000' Unspecified number of segments accepted.

B'001' 2 segments accepted.

B'010' 4 segments accepted.

B'011' 8 segments accepted.

B'100' 16 segments accepted.

B'101' 32 segments accepted.

B'110' 64 segments accepted.

B'111' Greater than 64 segments accepted.

/* max-APDU-length-accepted

B'0000' Up to MinimumMessageSize (50 octets)

B'0001' Up to 128 octets

B'0010' Up to 206 octets (fits in a LonTalk frame)

B'0011' Up to 480 octets (fits in an ARCNET frame)

B'0100' Up to 1024 octets

B'0101' Up to 1476 octets (fits in an ISO 8802-3 frame)

B'0110' reserved by ASHRAE

B'0111' reserved by ASHRAE

B'1000' reserved by ASHRAE

B'1001' reserved by ASHRAE

B'1010' reserved by ASHRAE

B'1011' reserved by ASHRAE

B'1100' reserved by ASHRAE

B'1101' reserved by ASHRAE

B'1110' reserved by ASHRAE

B'1111' reserved by ASHRAE

/* Encoding of BACNET Length/Value/Type tag

From clause 20.2.1.3.1

B'000' interpreted as Value = FALSE if application class == BOOLEAN

B'001' interpreted as Value = TRUE if application class == BOOLEAN

B'000' interpreted as Length = 0 if application class != BOOLEAN

B'001' interpreted as Length = 1

B'010' interpreted as Length = 2

B'011' interpreted as Length = 3

B'100' interpreted as Length = 4

B'101' interpreted as Length > 4

B'110' interpreted as Type = Opening Tag

B'111' interpreted as Type = Closing Tag

/**

* Encode the max APDU value and return the encoded octed.

* @param max_segs from clause 20.1.2.4 max-segments-accepted

* @param max_apdu from clause 20.1.2.5 max-APDU-length-accepted

* @return The encoded octet

uint8_t encode_max_segs_max_apdu(int max_segs, int max_apdu)

{

uint8_t octet = 0;

if (max_segs < 2) {

octet = 0;

} else if (max_segs < 4) {

octet = 0x10;

} else if (max_segs < 8) {

octet = 0x20;

} else if (max_segs < 16) {

octet = 0x30;

} else if (max_segs < 32) {

octet = 0x40;

} else if (max_segs < 64) {

octet = 0x50;

} else if (max_segs == 64) {

octet = 0x60;

} else {

octet = 0x70;

}

/* max_apdu must be 50 octets minimum */

if (max_apdu <= 50) {

octet |= 0x00;

} else if (max_apdu <= 128) {

octet |= 0x01;

/*fits in a LonTalk frame */

} else if (max_apdu <= 206) {

octet |= 0x02;

/*fits in an ARCNET or MS/TP frame */

} else if (max_apdu <= 480) {

octet |= 0x03;

} else if (max_apdu <= 1024) {

octet |= 0x04;

/* fits in an ISO 8802-3 frame */

} else if (max_apdu <= 1476) {

octet |= 0x05;

}

return octet;

}

/**

* Decode the given octed into a maximum segments value.

* @param octed From clause 20.1.2.4 max-segments-accepted

* and clause 20.1.2.5 max-APDU-length-accepted

* @return Returns the maximum segments value.

int decode_max_segs(uint8_t octet)

{

int max_segs = 0;

switch (octet & 0xF0) {

case 0:

max_segs = 0;

break;

case 0x10:

max_segs = 2;

break;

case 0x20:

max_segs = 4;

break;

case 0x30:

max_segs = 8;

break;

case 0x40:

max_segs = 16;

break;

case 0x50:

max_segs = 32;

break;

case 0x60:

max_segs = 64;

break;

case 0x70:

max_segs = 65;

break;

default:

break;

}

return max_segs;

}

/**

* Decode the given octed into a maximum APDU value.

* @param octet From clause 20.1.2.4 max-segments-accepted

* and clause 20.1.2.5 max-APDU-length-accepted

* @return Returns the maximum APDU value.

int decode_max_apdu(uint8_t octet)

{

int max_apdu = 0;

switch (octet & 0x0F) {

case 0:

max_apdu = 50;

break;

case 1:

max_apdu = 128;

break;

case 2:

max_apdu = 206;

break;

case 3:

max_apdu = 480;

break;

case 4:

max_apdu = 1024;

break;

case 5:

max_apdu = 1476;

break;

default:

break;

}

return max_apdu;

}

/**

* Encode a BACnet tag and returns the number of bytes consumed.

* (From clause 20.2.1 General Rules for Encoding BACnet Tags)

* @param apdu Pointer to the encode buffer, or NULL for length

* @param tag_number Number of the tag to encode,

* see BACNET_APPLICATION_TAG_X macros.

* @param context_specific Indicates to encode in the given context.

* @param len_value_type Indicates the length of the tag's content.

* @return Returns the number of apdu bytes consumed.

int encode_tag(

uint8_t *apdu,

uint8_t tag_number,

bool context_specific,

uint32_t len_value_type)

{

int len = 1; /* return value */

uint8_t *apdu_offset = NULL;

if (apdu) {

apdu[0] = 0;

}

if (context_specific) {

if (apdu) {

apdu[0] = BIT(3);

}

/* additional tag byte after this byte */

/* for extended tag byte */

if (tag_number <= 14) {

if (apdu) {

apdu[0] |= (tag_number << 4);

}

} else {

if (apdu) {

apdu[0] |= 0xF0;

apdu[1] = tag_number;

}

len++;

}

/* NOTE: additional len byte(s) after extended tag byte */

/* if larger than 4 */

if (len_value_type <= 4) {

if (apdu) {

apdu[0] |= len_value_type;

}

} else {

if (apdu) {

apdu[0] |= 5;

}

if (len_value_type <= 253) {

if (apdu) {

apdu[len] = (uint8_t)len_value_type;

}

len++;

} else if (len_value_type <= 65535) {

if (apdu) {

apdu[len] = 254;

}

len++;

if (apdu) {

apdu_offset = &apdu[len];

}

len += encode_unsigned16(apdu_offset, (uint16_t)len_value_type);

} else {

if (apdu) {

apdu[len] = 255;

}

len++;

if (apdu) {

apdu_offset = &apdu[len];

}

len += encode_unsigned32(apdu_offset, len_value_type);

}

return len;

}

/**

* @brief Encode a BACnet opening tag and returns the number

* of bytes consumed. From clause 20.2.1.3.2 Constructed Data.

* An "opening" tag whose Tag Number field shall contain the value

* of the tag number, whose Class field shall indicate

* "context specific," and whose length/value/type field shall

* have the value B'110';

* @param apdu Pointer to the encode buffer, or NULL for length

* @param tag_number Number of the tag to encode,

* see BACNET_APPLICATION_TAG_X macros.

* @return Returns the number of apdu bytes consumed.

int encode_opening_tag(uint8_t *apdu, uint8_t tag_number)

{

int len = 1;

if (apdu) {

/* set class field to context specific */

apdu[0] = BIT(3);

}

/* additional tag byte after this byte for extended tag byte */

if (tag_number <= 14) {

if (apdu) {

apdu[0] |= (tag_number << 4);

}

} else {

if (apdu) {

apdu[0] |= 0xF0;

apdu[1] = tag_number;

}

len++;

}

if (apdu) {

/* set type field to opening tag */

apdu[0] |= 6;

}

return len;

}

/**

* Encode a BACnet closing tag and returns the number

* of bytes consumed. From clause 20.2.1.3.2 Constructed Data:

* A "closing" tag, whose Class and Tag Number fields shall

* contain the same values as the "opening" tag and whose

* length/value/type field shall have the value B'111'.

* @param apdu Pointer to the encode buffer, or NULL for length

* @param tag_number Number of the tag to encode,

* see BACNET_APPLICATION_TAG_X macros.

* @return Returns the number of apdu bytes consumed.

int encode_closing_tag(uint8_t *apdu, uint8_t tag_number)

{

int len = 1;

/* set class field to context specific */

if (apdu) {

apdu[0] = BIT(3);

}

/* additional tag byte after this byte for extended tag byte */

if (tag_number <= 14) {

if (apdu) {

apdu[0] |= (tag_number << 4);

}

} else {

if (apdu) {

apdu[0] |= 0xF0;

apdu[1] = tag_number;

}

len++;

}

if (apdu) {

/* set type field to closing tag */

apdu[0] |= 7;

}

return len;

}

#if defined(BACNET_STACK_DEPRECATED_DISABLE)

/**

* Decode a BACnet tag and returns the number of bytes consumed.

* @param apdu Pointer to the encode buffer

* @param tag_number Place holder for number of the tag decoded

* see BACNET_APPLICATION_TAG_X macros.

* @return Returns the number of apdu bytes consumed.

* @deprecated Use bacnet_tag_number_decode() instead

int decode_tag_number(const uint8_t *apdu, uint8_t *tag_number)

{

int len = 1; /* return value */

/* decode the tag number first */

if (IS_EXTENDED_TAG_NUMBER(apdu[0])) {

/* extended tag */

if (tag_number) {

*tag_number = apdu[1];

}

len++;

} else {

if (tag_number) {

*tag_number = (uint8_t)(apdu[0] >> 4);

}

return len;

}

#endif

/**

* @brief Decode the BACnet Tag Number

* as defined in clause 20.2.1.2 Tag Number

* Bit Number:

* 7 6 5 4 3 2 1 0

* |-----|-----|-----|-----|-----|-----|-----|-----|

* | Tag Number |Class|Length/Value/Type|

* |-----|-----|-----|-----|-----|-----|-----|-----|

* Tag numbers ranging from zero to 14 (inclusive) shall be encoded

* in the Tag Number field of the initial octet as a four bit

* binary integer with bit 7 the most significant bit.

* Tag numbers ranging from 15 to 254 (inclusive) shall be encoded by

* setting the Tag Number field of the initial octet to B'1111'

* and following the initial tag octet by an octet containing the

* tag number represented as an eight-bit binary integer with bit 7 the

* most significant bit.

* The encoding does not allow, nor does BACnet require, tag numbers

* larger than 254. The value B'11111111' of the subsequent

* octet is reserved by ASHRAE.

* @param apdu - buffer to hold the bytes

* @param apdu_size - number of bytes in the buffer to decode

* @param tag_number - BACnet tag number

* @return number of bytes decoded, or zero if errors occur

int bacnet_tag_number_decode(

const uint8_t *apdu, uint32_t apdu_size, uint8_t *tag_number)

{

int len = 0; /* return value */

if (apdu_size >= 1) {

if (IS_EXTENDED_TAG_NUMBER(apdu[0])) {

if (apdu_size >= 2) {

/* extended tag */

if (tag_number) {

*tag_number = apdu[1];

}

len = 2;

} else {

/* malfomed */

len = 0;

}

} else {

if (tag_number) {

*tag_number = (uint8_t)(apdu[0] >> 4);

}

len = 1;

}

return len;

}

/**

* @brief Encode a BACnet BACnet Tag Number and Value

* as defined in clause 20.2.1 General Rules for Encoding BACnet Tags

* @param apdu - buffer to hold the data to be encoded, or NULL for length

* @param apdu_size - number of bytes in the buffer

* @param tag - tag value to encode

* @return returns the number of apdu bytes consumed,

* or 0 if apdu_size is too small to fit the data

int bacnet_tag_encode(uint8_t *apdu, uint32_t apdu_size, const BACNET_TAG *tag)

{

int apdu_len = 0; /* total length of the apdu, return value */

if (!tag) {

return 0;

}

if (tag->application) {

apdu_len = encode_tag(NULL, tag->number, false, tag->len_value_type);

} else if (tag->context) {

apdu_len = encode_tag(NULL, tag->number, true, tag->len_value_type);

} else if (tag->opening) {

apdu_len = encode_opening_tag(NULL, tag->number);

} else if (tag->closing) {

apdu_len = encode_closing_tag(NULL, tag->number);

}

if (apdu_len > apdu_size) {

apdu_len = 0;

} else {

if (tag->application) {

apdu_len =

encode_tag(apdu, tag->number, false, tag->len_value_type);

} else if (tag->context) {

apdu_len = encode_tag(apdu, tag->number, true, tag->len_value_type);

} else if (tag->opening) {

apdu_len = encode_opening_tag(apdu, tag->number);

} else if (tag->closing) {

apdu_len = encode_closing_tag(apdu, tag->number);

}

return apdu_len;

}

/**

* @brief Decode the BACnet Tag Number and Value

* as defined in clause 20.2.1 General Rules For Encoding BACnet Tags

* @param apdu - buffer of data to be decoded

* @param apdu_size - number of bytes in the buffer

* @param tag - decoded tag data, if decoded

* @return the number of apdu bytes consumed, or zero if malformed

int bacnet_tag_decode(const uint8_t *apdu, uint32_t apdu_size, BACNET_TAG *tag)

{

int len = 0;

uint8_t tag_number = 0;

bool application_tag = false;

bool context_tag = false;

bool opening_tag = false;

bool closing_tag = false;

uint32_t len_value_type = 0;

if (apdu && (apdu_size > 0)) {

len = bacnet_tag_number_decode(&apdu[0], apdu_size, &tag_number);

}

if (len > 0) {

if (IS_EXTENDED_VALUE(apdu[0])) {

if (apdu_size > len) {

apdu_size -= len;

if ((apdu[len] == 255) && (apdu_size >= 5)) {

/* tagged as uint32_t */

uint32_t value32;

len++;

len += decode_unsigned32(&apdu[len], &value32);

len_value_type = value32;

} else if ((apdu[len] == 254) && (apdu_size >= 3)) {

/* tagged as uint16_t */

uint16_t value16;

len++;

len += decode_unsigned16(&apdu[len], &value16);

len_value_type = value16;

} else if ((apdu[len] < 254) && (apdu_size >= 1)) {

/* no tag - must be uint8_t */

len_value_type = apdu[len];

len++;

} else {

/* packet is malformed */

len = 0;

}

} else {

/* packet is malformed */

len = 0;

}

} else if (IS_OPENING_TAG(apdu[0])) {

/* reserved value */

} else if (IS_CLOSING_TAG(apdu[0])) {

/* reserved value */

} else {

/* small value */

len_value_type = apdu[0] & 0x07;

}

if (IS_CONTEXT_SPECIFIC(apdu[0])) {

if (IS_OPENING_TAG(apdu[0])) {

opening_tag = true;

} else if (IS_CLOSING_TAG(apdu[0])) {

closing_tag = true;

} else {

context_tag = true;

}

} else {

application_tag = true;

}

if ((len > 0) && tag) {

tag->number = tag_number;

tag->application = application_tag;

tag->context = context_tag;

tag->opening = opening_tag;

tag->closing = closing_tag;

tag->len_value_type = len_value_type;

}

return len;

}

#if defined(BACNET_STACK_DEPRECATED_DISABLE)

/**

* @brief Returns if at the given pointer a

* opening tag has been found.

* @param apdu Pointer to the tag number.

* @return true/false

* @deprecated Use bacnet_is_opening_tag() instead

bool decode_is_opening_tag(const uint8_t *apdu)

{

return (bool)((apdu[0] & 0x07) == 6);

}

#endif

/**

* @brief Returns true if an opening tag has been found.

* @param apdu Pointer to the tag number.

* @param apdu_size Number of bytes available to decode

* @return true if an opening tag has been found.

bool bacnet_is_opening_tag(const uint8_t *apdu, uint32_t apdu_size)

{

bool tag = false;

if (apdu_size > 0) {

if (IS_CONTEXT_SPECIFIC(apdu[0]) && (IS_OPENING_TAG(apdu[0]))) {

tag = true;

}

return tag;

}

#if defined(BACNET_STACK_DEPRECATED_DISABLE)

/**

* @brief Returns if at the given pointer a

* closing tag has been found.

* @param apdu Pointer to the tag number.

* @return true/false

* @deprecated Use bacnet_is_closing_tag() instead

bool decode_is_closing_tag(const uint8_t *apdu)

{

return (bool)((apdu[0] & 0x07) == 7);

}

#endif

/**

* @brief Returns true if a closing tag has been found.

* @param apdu Pointer to the tag number.

* @param apdu_size Number of bytes available to decode

* @return true if a closing tag has been found.

bool bacnet_is_closing_tag(const uint8_t *apdu, uint32_t apdu_size)

{

bool tag = false;

if (apdu_size > 0) {

if (IS_CONTEXT_SPECIFIC(apdu[0]) && (IS_CLOSING_TAG(apdu[0]))) {

tag = true;

}

return tag;

}

/**

* @brief Returns true if a context specific tag has been found.

* @param apdu Pointer to the tag number.

* @param apdu_size Number of bytes available to decode

* @return true if a context specific tag has been found.

bool bacnet_is_context_specific(const uint8_t *apdu, uint32_t apdu_size)

{

bool tag = false;

if (apdu_size > 0) {

if (IS_CONTEXT_SPECIFIC(apdu[0])) {

tag = true;

}

return tag;

}

#if defined(BACNET_STACK_DEPRECATED_DISABLE)

/**

* @brief Decodes the tag number and the value,

* that the APDU pointer is addressing.

* (From clause 20.2.1.3.2 Constructed Data)

* @param apdu Pointer to the message buffer.

* @param tag_number Pointer to a variable

* taking the tag number.

* @param value Pointer to a variable

* taking the value.

* @return number of bytes decoded, or zero if errors occur

* @deprecated Use bacnet_tag_decode() instead

int decode_tag_number_and_value(

const uint8_t *apdu, uint8_t *tag_number, uint32_t *value)

{

int len = 1;

uint16_t value16;

uint32_t value32;

len = decode_tag_number(&apdu[0], tag_number);

if (IS_EXTENDED_VALUE(apdu[0])) {

/* tagged as uint32_t */

if (apdu[len] == 255) {

len++;

value32 = 0;

len += decode_unsigned32(&apdu[len], &value32);

if (value) {

*value = value32;

}

/* tagged as uint16_t */

else if (apdu[len] == 254) {

len++;

value16 = 0;

len += decode_unsigned16(&apdu[len], &value16);

if (value) {

*value = value16;

}

/* no tag - must be uint8_t */

else {

if (value) {

*value = apdu[len];

}

len++;

}

} else if (IS_OPENING_TAG(apdu[0]) && value) {

/* opening tag */

*value = 0;

} else if (IS_CLOSING_TAG(apdu[0]) && value) {

/* closing tag */

*value = 0;

} else if (value) {

/* small value */

*value = apdu[0] & 0x07;

}

return len;

}

#endif

#if defined(BACNET_STACK_DEPRECATED_DISABLE)

/**

* @brief Decode the BACnet Tag Number and Value

* as defined in clause 20.2.1.3.2 Constructed Data

* @param apdu - buffer of data to be decoded

* @param apdu_size - number of bytes in the buffer

* @param tag_number - decoded tag number, if decoded

* @param value - decoded value, if decoded

* @return the number of apdu bytes consumed, or zero if errors occur

* @deprecated use bacnet_tag_decode() instead

int bacnet_tag_number_and_value_decode(

const uint8_t *apdu,

uint32_t apdu_size,

uint8_t *tag_number,

uint32_t *value)

{

int len = 0;

BACNET_TAG tag = { 0 };

len = bacnet_tag_decode(apdu, apdu_size, &tag);

if (len > 0) {

if (value) {

*value = tag.len_value_type;

}

if (value) {

*tag_number = tag.number;

}

return len;

}

#endif

/**

* @brief Determine the data length from the application tag number

* @param tag_number application tag number to be evaluated.

* @param len_value_type Length of the data in bytes.

* @return datalength for the given tag, or INT_MAX if out of range.

int bacnet_application_data_length(uint8_t tag_number, uint32_t len_value_type)

{

int len = 0;

switch (tag_number) {

case BACNET_APPLICATION_TAG_NULL:

break;

case BACNET_APPLICATION_TAG_BOOLEAN:

break;

case BACNET_APPLICATION_TAG_UNSIGNED_INT:

case BACNET_APPLICATION_TAG_SIGNED_INT:

case BACNET_APPLICATION_TAG_REAL:

case BACNET_APPLICATION_TAG_DOUBLE:

case BACNET_APPLICATION_TAG_OCTET_STRING:

case BACNET_APPLICATION_TAG_CHARACTER_STRING:

case BACNET_APPLICATION_TAG_BIT_STRING:

case BACNET_APPLICATION_TAG_ENUMERATED:

case BACNET_APPLICATION_TAG_DATE:

case BACNET_APPLICATION_TAG_TIME:

case BACNET_APPLICATION_TAG_OBJECT_ID:

len = INT_MAX;

if (len_value_type < INT_MAX) {

len = (int)len_value_type;

}

break;

default:

break;

}

return len;

}

/**

* @brief Returns the length of data between an opening tag and a closing tag.

* @note Expects that the first octet contain the opening tag.

* @param apdu Pointer to the APDU buffer

* @param apdu_size Bytes valid in the buffer

* @param property ID of the property to get the length for.

* @return length of data between an opening tag and a closing tag 0..N,

* or BACNET_STATUS_ERROR.

int bacnet_enclosed_data_length(const uint8_t *apdu, size_t apdu_size)

{

int len = 0;

int total_len = 0;

int apdu_len = 0;

BACNET_TAG tag = { 0 };

uint8_t opening_tag_number = 0;

size_t opening_tag_number_counter = 0;

bool total_len_enable = false;

if (!apdu) {

return BACNET_STATUS_ERROR;

}

if (apdu_size <= apdu_len) {

/* error: exceeding our buffer limit */

return BACNET_STATUS_ERROR;

}

if (!bacnet_is_opening_tag(apdu, apdu_size)) {

/* error: opening tag is missing */

return BACNET_STATUS_ERROR;

}

do {

len = bacnet_tag_decode(apdu, apdu_size - apdu_len, &tag);

if (len == 0) {

return BACNET_STATUS_ERROR;

}

if (tag.opening) {

if (opening_tag_number_counter == 0) {

opening_tag_number = tag.number;

opening_tag_number_counter = 1;

total_len_enable = false;

} else if (tag.number == opening_tag_number) {

total_len_enable = true;

opening_tag_number_counter++;

} else {

total_len_enable = true;

}

} else if (tag.closing) {

if (tag.number == opening_tag_number) {

if (opening_tag_number_counter > 0) {

opening_tag_number_counter--;

}

total_len_enable = true;

} else if (tag.context) {

/* note: bound the SUM, not only the addend: len already holds

the size of this tag's header */

if (tag.len_value_type > (uint32_t)(INT_MAX - len)) {

/* error: length is out of range */

return BACNET_STATUS_ERROR;

}

len += tag.len_value_type;

total_len_enable = true;

} else {

if (tag.len_value_type > (uint32_t)(INT_MAX - len)) {

/* error: length is out of range */

return BACNET_STATUS_ERROR;

}

/* application tagged data */

len +=

bacnet_application_data_length(tag.number, tag.len_value_type);

total_len_enable = true;

}

if (opening_tag_number_counter > 0) {

if (len > 0) {

if (total_len_enable) {

if (len > (INT_MAX - total_len)) {

/* error: length is out of range */

return BACNET_STATUS_ERROR;

}

total_len += len;

}

} else {

/* error: len is not incrementing */

return BACNET_STATUS_ERROR;

}

if (len > (INT_MAX - apdu_len)) {

/* error: length is out of range */

return BACNET_STATUS_ERROR;

}

apdu_len += len;

if (apdu_size <= apdu_len) {

/* error: exceeding our buffer limit */

return BACNET_STATUS_ERROR;

}

apdu += len;

}

} while (opening_tag_number_counter > 0);

return total_len;

}

#if defined(BACNET_STACK_DEPRECATED_DISABLE)

/**

* @brief Returns true if the tag is context specific

* and matches, as defined in clause 20.2.1.3.2 Constructed

* Data.

* @param apdu Pointer to the tag begin.

* @param tag_number Tag number, that has been decoded before.

* @return true on a match, false otherwise.

* @deprecated Use bacnet_is_context_tag_number() instead

bool decode_is_context_tag(const uint8_t *apdu, uint8_t tag_number)

{

uint8_t my_tag_number = 0;

decode_tag_number(apdu, &my_tag_number);

return (bool)(IS_CONTEXT_SPECIFIC(*apdu) && (my_tag_number == tag_number));

}

#endif

#if defined(BACNET_STACK_DEPRECATED_DISABLE)

/**

* @brief Returns true if the tag is context specific

* and matches, as defined in clause 20.2.1.3.2 Constructed

* Data. This function returns the tag length as well.

* @param apdu Pointer to the tag begin.

* @param tag_number Tag number, that has been decoded before.

* @param tag_length Pointer to a variable, taking the

* length of the tag in bytes.

* @return true on a match, false otherwise.

* @deprecated Use bacnet_is_context_tag_number() instead

bool decode_is_context_tag_with_length(

const uint8_t *apdu, uint8_t tag_number, int *tag_length)

{

uint8_t my_tag_number = 0;

*tag_length = decode_tag_number(apdu, &my_tag_number);

return (bool)(IS_CONTEXT_SPECIFIC(*apdu) && (my_tag_number == tag_number));

}

#endif

/**

* @brief Returns true if the tag is context specific

* and matches, as defined in clause 20.2.1.3.2 Constructed

* Data. This function returns the tag length as well.

* @param apdu Pointer to the tag begin.

* @param apdu_size - number of bytes in the buffer

* @param tag_number Tag number, that has been decoded before.

* @param tag_length Pointer to a variable, or NULL.

* Returns the length of the tag in bytes if not NULL.

* @param len_value_type Pointer to a variable, or NULL.

* Returns the len_value_type of the tag in bytes if not NULL.

* @return true on a match, false otherwise.

bool bacnet_is_context_tag_number(

const uint8_t *apdu,

uint32_t apdu_size,

uint8_t tag_number,

int *tag_length,

uint32_t *len_value_type)

{

bool match = false;

int len;

BACNET_TAG tag = { 0 };

len = bacnet_tag_decode(apdu, apdu_size, &tag);

if (len > 0) {

if (tag.context && (tag.number == tag_number)) {

if (tag_length) {

*tag_length = len;

}

if (len_value_type) {

*len_value_type = tag.len_value_type;

}

match = true;

}

return match;

}

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bacnet-stack/src/bacnet/bacdcode.c at master · bacnet-stack/bacnet-stack · GitHub

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