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Feature/comments and review (#102)

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* Added comments. Replaced -1 with BACNET_STATUS_ERROR macro.

* Added some DogyGen comments

* Added missing return value check for booleans.

* Check used bits against unused bits in bitstrings.

* Added missing return value check for bitstrings.

* Added sanity checks and comments.

* Fixed implicit type conv warning.

* Chose to keep simpler C function methods.

Co-authored-by: Steve Karg <steve@kargs.net>
Co-authored-by: Steve Karg <skarg@users.sourceforge.net>
This commit is contained in:
Roy Schneider
2020-07-14 18:41:51 +02:00
committed by GitHub
parent de7f7e9782
commit 2af16ab14d
5 changed files with 838 additions and 234 deletions
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src/bacnet/bacdcode.c
+264 -55
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@@ -90,9 +90,14 @@
B'111' interpreted as Type = Closing Tag
*/
/* from clause 20.1.2.4 max-segments-accepted */
/* and clause 20.1.2.5 max-APDU-length-accepted */
/* returns the encoded octet */
/**
* 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;
@@ -136,9 +141,14 @@ uint8_t encode_max_segs_max_apdu(int max_segs, int max_apdu)
return octet;
}
/* from clause 20.1.2.4 max-segments-accepted */
/* and clause 20.1.2.5 max-APDU-length-accepted */
/* returns the encoded 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;
@@ -175,6 +185,14 @@ int decode_max_segs(uint8_t octet)
return max_segs;
}
/**
* Decode the given octed into a maximum APDU 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 APDU value.
*/
int decode_max_apdu(uint8_t octet)
{
int max_apdu = 0;
@@ -205,8 +223,18 @@ int decode_max_apdu(uint8_t octet)
return max_apdu;
}
/* from clause 20.2.1 General Rules for Encoding BACnet Tags */
/* returns the number of apdu bytes consumed */
/**
* 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.
* @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,
@@ -249,8 +277,17 @@ int encode_tag(uint8_t *apdu,
return len;
}
/* from clause 20.2.1.3.2 Constructed Data */
/* returns the number of apdu bytes consumed */
/**
* Encode a BACnet opening tag and returns the number
* of bytes consumed.
* (From clause 20.2.1.3.2 Constructed Data.)
*
* @param apdu Pointer to the encode buffer.
* @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;
@@ -271,8 +308,17 @@ int encode_opening_tag(uint8_t *apdu, uint8_t tag_number)
return len;
}
/* from clause 20.2.1.3.2 Constructed Data */
/* returns the number of apdu bytes consumed */
/**
* Encode a BACnet closing tag and returns the number
* of bytes consumed.
* (From clause 20.2.1.3.2 Constructed Data.)
*
* @param apdu Pointer to the encode buffer.
* @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;
@@ -345,20 +391,45 @@ int bacnet_tag_number_decode(
return len;
}
/**
* @brief Returns if at the given pointer a
* opening tag has been found.
*
* @param apdu Pointer to the tag number.
*
* @return true/false
*/
bool decode_is_opening_tag(uint8_t *apdu)
{
return (bool)((apdu[0] & 0x07) == 6);
}
/* from clause 20.2.1.3.2 Constructed Data */
/* returns the number of apdu bytes consumed */
/**
* @brief Returns if at the given pointer a
* closing tag has been found.
*
* @param apdu Pointer to the tag number.
*
* @return true/false
*/
bool decode_is_closing_tag(uint8_t *apdu)
{
return (bool)((apdu[0] & 0x07) == 7);
}
/* from clause 20.2.1.3.2 Constructed Data */
/* returns the number of apdu bytes consumed */
/**
* @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
*/
int decode_tag_number_and_value(
uint8_t *apdu, uint8_t *tag_number, uint32_t *value)
{
@@ -371,6 +442,7 @@ int decode_tag_number_and_value(
/* tagged as uint32_t */
if (apdu[len] == 255) {
len++;
value32 = 0;
len += decode_unsigned32(&apdu[len], &value32);
if (value) {
*value = value32;
@@ -379,6 +451,7 @@ int decode_tag_number_and_value(
/* tagged as uint16_t */
else if (apdu[len] == 254) {
len++;
value16 = 0;
len += decode_unsigned16(&apdu[len], &value16);
if (value) {
*value = value16;
@@ -392,6 +465,7 @@ int decode_tag_number_and_value(
len++;
}
} else if (IS_OPENING_TAG(apdu[0]) && value) {
/* opening tag */
*value = 0;
} else if (IS_CLOSING_TAG(apdu[0]) && value) {
/* closing tag */
@@ -466,16 +540,37 @@ int bacnet_tag_number_and_value_decode(
return len;
}
/* from clause 20.2.1.3.2 Constructed Data */
/* returns true if the tag is context specific and matches */
/**
* @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.
*/
bool decode_is_context_tag(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));
}
/**
* @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.
*/
bool decode_is_context_tag_with_length(
uint8_t *apdu, uint8_t tag_number, int *tag_length)
{
@@ -486,18 +581,35 @@ bool decode_is_context_tag_with_length(
return (bool)(IS_CONTEXT_SPECIFIC(*apdu) && (my_tag_number == tag_number));
}
/* from clause 20.2.1.3.2 Constructed Data */
/* returns the true if the tag matches */
/**
* @brief Returns true if the tag does match and it
* is an opening tag as well.
* 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.
*/
bool decode_is_opening_tag_number(uint8_t *apdu, uint8_t tag_number)
{
uint8_t my_tag_number = 0;
decode_tag_number(apdu, &my_tag_number);
return (bool)(IS_OPENING_TAG(apdu[0]) && (my_tag_number == tag_number));
}
/* from clause 20.2.1.3.2 Constructed Data */
/* returns the number of apdu bytes consumed */
/**
* @brief Returns true if the tag does match and it
* is an closing tag as well.
* 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.
*/
bool decode_is_closing_tag_number(uint8_t *apdu, uint8_t tag_number)
{
uint8_t my_tag_number = 0;
@@ -506,28 +618,49 @@ bool decode_is_closing_tag_number(uint8_t *apdu, uint8_t tag_number)
return (bool)(IS_CLOSING_TAG(apdu[0]) && (my_tag_number == tag_number));
}
/* from clause 20.2.3 Encoding of a Boolean Value */
/* and 20.2.1 General Rules for Encoding BACnet Tags */
/* returns the number of apdu bytes consumed */
/**
* @brief Encode an boolean value.
* From clause 20.2.3 Encoding of a Boolean Value
* and 20.2.1 General Rules for Encoding BACnet Tags.
*
* @param apdu Pointer to the encode buffer.
* @param boolean_value Boolean value to encode.
*
* @return returns the number of apdu bytes consumed
*/
int encode_application_boolean(uint8_t *apdu, bool boolean_value)
{
int len = 0;
uint32_t len_value = 0;
uint32_t len_value;
if (boolean_value) {
len_value = 1;
} else {
len_value = 0;
}
len =
encode_tag(&apdu[0], BACNET_APPLICATION_TAG_BOOLEAN, false, len_value);
return len;
}
/* context tagged is encoded differently */
/**
* @brief Encode an boolean value in a context.
* From clause 20.2.3 Encoding of a Boolean Value
* and 20.2.1 General Rules for Encoding BACnet Tags.
*
* @param apdu Pointer to the encode buffer.
* @param tag_number Tag number in which context
* the value shall be encoded.
* @param boolean_value Boolean value to encode.
*
* @return returns the number of apdu bytes consumed
*/
int encode_context_boolean(
uint8_t *apdu, uint8_t tag_number, bool boolean_value)
{
int len = 0; /* return value */
int len; /* return value */
len = encode_tag(&apdu[0], (uint8_t)tag_number, true, 1);
apdu[len] = (bool)(boolean_value ? 1 : 0);
@@ -536,6 +669,13 @@ int encode_context_boolean(
return len;
}
/**
* @brief Decode an boolean value.
*
* @param apdu Pointer to the encode buffer.
*
* @return true/false
*/
bool decode_context_boolean(uint8_t *apdu)
{
bool boolean_value = false;
@@ -547,6 +687,17 @@ bool decode_context_boolean(uint8_t *apdu)
return boolean_value;
}
/**
* @brief Decode an boolean value in the context of a tag.
*
* @param apdu Pointer to the encode buffer.
* @param tag_number Tag number in which context
* the value shall be encoded.
* @param boolean_value Pointer to a boolean variable
* taking the value.
*
* @return The count of bytes decoded or BACNET_STATUS_ERROR.
*/
int decode_context_boolean2(
uint8_t *apdu, uint8_t tag_number, bool *boolean_value)
{
@@ -564,33 +715,65 @@ int decode_context_boolean2(
return len;
}
/* from clause 20.2.3 Encoding of a Boolean Value */
/* and 20.2.1 General Rules for Encoding BACnet Tags */
/* returns the number of apdu bytes consumed */
/**
* @brief Check the length value and return the boolean meaning.
* From clause 20.2.3 Encoding of a Boolean Value
* and 20.2.1 General Rules for Encoding BACnet Tags.
*
* @param len_value Tag length value.
*
* @return true/false
*/
bool decode_boolean(uint32_t len_value)
{
bool boolean_value = false;
bool boolean_value;
if (len_value) {
boolean_value = true;
} else {
boolean_value = false;
}
return boolean_value;
}
/* from clause 20.2.2 Encoding of a Null Value */
/* and 20.2.1 General Rules for Encoding BACnet Tags */
/* returns the number of apdu bytes consumed */
/**
* @brief Encode a Null value.
* From clause 20.2.2 Encoding of a Null Value
* and 20.2.1 General Rules for Encoding BACnet Tags.
*
* @param apdu Pointer to the encode buffer.
*
* @return returns the number of apdu bytes consumed.
*/
int encode_application_null(uint8_t *apdu)
{
return encode_tag(&apdu[0], BACNET_APPLICATION_TAG_NULL, false, 0);
}
/**
* @brief Encode a Null value in a tag context.
* From clause 20.2.2 Encoding of a Null Value
* and 20.2.1 General Rules for Encoding BACnet Tags.
*
* @param apdu Pointer to the encode buffer.
* @param tag_number Tag number in which context
* the value shall be encoded.
*
* @return returns the number of apdu bytes consumed.
*/
int encode_context_null(uint8_t *apdu, uint8_t tag_number)
{
return encode_tag(&apdu[0], tag_number, true, 0);
}
/**
* @brief Reverse the bits of the given byte.
*
* @param in_byte Byte to reverse.
*
* @return Byte with reversed bit order.
*/
static uint8_t byte_reverse_bits(uint8_t in_byte)
{
uint8_t out_byte = 0;
@@ -623,35 +806,61 @@ static uint8_t byte_reverse_bits(uint8_t in_byte)
return out_byte;
}
/* from clause 20.2.10 Encoding of a Bit String Value */
/* returns the number of apdu bytes consumed */
/**
* @brief Decode a bit string value.
* (From clause 20.2.10 Encoding of a Bit String Value.)
*
* @param apdu Pointer to the buffer holding the message data.
* @param len_value Length of the Data to decode.
* @param bit_string Pointer to the bit string variable,
* taking the decoded result.
*
* @return Returns the number of apdu bytes consumed.
*/
int decode_bitstring(
uint8_t *apdu, uint32_t len_value, BACNET_BIT_STRING *bit_string)
uint8_t * apdu,
uint32_t len_value,
BACNET_BIT_STRING * bit_string)
{
int len = 0;
uint8_t unused_bits = 0;
uint32_t i = 0;
uint32_t bytes_used = 0;
int len = 0; /* Return value */
uint8_t unused_bits;
uint32_t i;
uint32_t bytes_used;
bitstring_init(bit_string);
if (len_value) {
/* the first octet contains the unused bits */
bytes_used = len_value - 1;
if (bytes_used <= MAX_BITSTRING_BYTES) {
len = 1;
for (i = 0; i < bytes_used; i++) {
bitstring_set_octet(
bit_string, (uint8_t)i, byte_reverse_bits(apdu[len++]));
if (apdu && bit_string) {
/* Init/empty the string. */
bitstring_init(bit_string);
if (len_value) {
/* The first octet contains the unused bits. */
bytes_used = len_value - 1;
if (bytes_used <= MAX_BITSTRING_BYTES) {
len = 1;
/* Copy the bytes in reversed bit order. */
for (i = 0; i < bytes_used; i++) {
bitstring_set_octet(bit_string, (uint8_t) i,
byte_reverse_bits(apdu[len++]));
}
/* Erase the remaining unsed bits. */
unused_bits = (uint8_t) (apdu[0] & 0x07);
bitstring_set_bits_used(bit_string, (uint8_t) bytes_used,
unused_bits);
}
unused_bits = (uint8_t)(apdu[0] & 0x07);
bitstring_set_bits_used(
bit_string, (uint8_t)bytes_used, unused_bits);
}
}
return len;
}
/**
* @brief Decode a bit string value in the given context.
* (From clause 20.2.10 Encoding of a Bit String Value.)
*
* @param apdu Pointer to the buffer holding the message data.
* @param tag_number Tag number (context).
* @param bit_string Pointer to the bit string variable,
* taking the decoded result.
*
* @return Returns the number of bytes dcoded or BACNET_STATUS_ERROR.
*/
int decode_context_bitstring(
uint8_t *apdu, uint8_t tag_number, BACNET_BIT_STRING *bit_string)
{