DRep¶

typedef struct cardano_drep_t cardano_drep_t¶

In Voltaire, existing stake credentials will be able to delegate their stake to DReps for voting purposes, in addition to the current delegation to stake pools for block production.

Just as the number of blocks that a pool mint depends on the total stake, the amount of decision-making power will depend on the number of coins delegated to a DRep.

Registered DReps are identified by a credential that can be either:

• A verification key (Ed25519)

• A native or Plutus script

cardano_error_t cardano_drep_new(cardano_drep_type_t type, cardano_credential_t *credential, cardano_drep_t **drep)¶

Creates and initializes a new instance of a drep.

This function allocates and initializes a new instance of cardano_drep_t, using the provided type and credential. It returns an error code to indicate the success or failure of the operation.

Usage Example:

cardano_drep_type_t type = ...;  // Assume type is initialized here
cardano_credential_t* credential = ...;  // Assume credential is initialized here
cardano_drep_t* drep = NULL;

// Attempt to create a new drep
cardano_error_t result = cardano_drep_new(type, credential, &drep);

if (result == CARDANO_SUCCESS)
{
  // Use the drep

  // Once done, ensure to clean up and release the drep
  cardano_drep_unref(&drep);
}

cardano_credential_unref(&credential);

Parameters:¶

cardano_drep_type_t type¶

[in] The type of the drep, represented by cardano_drep_type_t.

cardano_credential_t *credential¶

[in] A pointer to cardano_credential_t representing the credential associated with this drep. The credential must be properly initialized before being passed to this function. Must be NULL if type is CARDANO_DREP_TYPE_ABSTAIN or CARDANO_DREP_TYPE_NO_CONFIDENCE.

cardano_drep_t **drep¶

[out] On successful initialization, this will point to a newly created cardano_drep_t object. This object represents a “strong reference” to the drep, meaning that it is fully initialized and ready for use. The caller is responsible for managing the lifecycle of this object. Specifically, once the drep is no longer needed, the caller must release it by calling cardano_drep_unref.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the drep was successfully created, or an appropriate error code indicating the failure reason.

cardano_error_t cardano_drep_from_string(const char *bech32_string, size_t string_length, cardano_drep_t **drep)¶

Converts a Bech32-encoded string representation of a DRep (Delegated Representative) into a cardano_drep_t object.

The input string can follow one of two formats:

1. CIP-105 Format (DEPRECATED):

   • This format represents the key hash directly as a Bech32-encoded string.

2. CIP-129 Format:

   • This format introduces a header byte to encode additional metadata about the governance key type and credential type.

   • The binary structure is as follows:

     Header Byte Structure:

     • The header byte consists of two parts:

       • Bits [7;4]: Key type (t t t t)

         • Defines the type of governance key being used.

         • Possible key types:

           • 0000 (CC Hot): Constitutional Committee Hot Key

           • 0001 (CC Cold): Constitutional Committee Cold Key

           • 0010 (DRep): Delegated Representative Key

       • Bits [3;0]: Credential type (c c c c)

         • Refers to the type of credential associated with the governance key.

         • Reserved values ensure no conflicts with Cardano address network tags:

           • 0010 (Key Hash): Key hash credential

           • 0011 (Script Hash): Script hash credential

const char* drep_bech32 = "drep1qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq";
size_t drep_length = strlen(drep_bech32);
cardano_drep_t* drep = NULL;

cardano_error_t result = cardano_drep_from_string(drep_bech32, drep_length, &drep);

if (result == CARDANO_SUCCESS)
{
  printf("DRep object successfully created.\n");
  // Use the drep object...
  cardano_drep_unref(drep);
}
else
{
  printf("Failed to parse DRep string: %d\n", result);
}

Note

The caller is responsible for freeing the memory associated with the returned cardano_drep_t object using cardano_drep_unref.

Parameters:¶

const char *bech32_string¶

[in] Pointer to the Bech32-encoded string.

size_t string_length¶

[in] Length of the input string.

cardano_drep_t **drep¶

[out] Pointer to the output cardano_drep_t object.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the drep was successfully created, or an appropriate error code indicating the failure reason.

cardano_error_t cardano_drep_from_cbor(cardano_cbor_reader_t *reader, cardano_drep_t **drep)¶

Creates a drep from a CBOR reader.

This function parses CBOR data using a provided cardano_cbor_reader_t and constructs a cardano_drep_t object. It assumes that the CBOR reader is set up correctly and that the CBOR data corresponds to the structure expected for a drep.

Usage Example:

cardano_cbor_reader_t* reader = cardano_cbor_reader_new(cbor_data, data_size);
cardano_drep_t* drep = NULL;

cardano_error_t result = cardano_drep_from_cbor(reader, &drep);

if (result == CARDANO_SUCCESS)
{
  // Use the drep

  // Once done, ensure to clean up and release the drep
  cardano_drep_unref(&drep);
}
else
{
  const char* error = cardano_cbor_reader_get_last_error(reader);
  printf("Failed to decode drep: %s\n", error);
}

cardano_cbor_reader_unref(&reader); // Cleanup the CBOR reader

Note

If the function fails, the last error can be retrieved by calling cardano_cbor_reader_get_last_error with the reader. The caller is responsible for freeing the created cardano_drep_t object by calling cardano_drep_unref when it is no longer needed.

Parameters:¶

cardano_cbor_reader_t *reader¶

[in] A pointer to an initialized cardano_cbor_reader_t that is ready to read the CBOR-encoded drep data.

cardano_drep_t **drep¶

[out] A pointer to a pointer of cardano_drep_t that will be set to the address of the newly created drep object upon successful decoding.

Returns:¶

A cardano_error_t value indicating the outcome of the operation. Returns CARDANO_SUCCESS if the drep was successfully created, or an appropriate error code if an error occurred.

cardano_error_t cardano_drep_to_cbor(const cardano_drep_t *drep, cardano_cbor_writer_t *writer)¶

Serializes a drep into CBOR format using a CBOR writer.

This function serializes the given cardano_drep_t object using a cardano_cbor_writer_t.

Usage Example:

cardano_drep_t* drep = ...;
cardano_cbor_writer_t* writer = cardano_cbor_writer_new();

if (writer)
{
  cardano_error_t result = cardano_drep_to_cbor(drep, writer);

  if (result == CARDANO_SUCCESS)
  {
    // Use the writer's buffer containing the serialized data
  }
  else
  {
    const char* error_message = cardano_cbor_writer_get_last_error(writer);
    printf("Serialization failed: %s\n", error_message);
  }

  cardano_cbor_writer_unref(&writer);
}

cardano_drep_unref(&drep);

Parameters:¶

const cardano_drep_t *drep¶

[in] A constant pointer to the cardano_drep_t object that is to be serialized.

cardano_cbor_writer_t *writer¶

[out] A pointer to a cardano_cbor_writer_t where the CBOR serialized data will be written. The writer must already be initialized and ready to accept the data.

Returns:¶

Returns CARDANO_SUCCESS if the serialization is successful. If the drep or writer is NULL, returns CARDANO_ERROR_POINTER_IS_NULL.

cardano_error_t cardano_drep_to_cip116_json(const cardano_drep_t *drep, cardano_json_writer_t *writer)¶

Serializes a DRep to CIP-116 JSON.

The function writes the full JSON object, including the surrounding braces.

Schema:

• Key Hash: { “tag”: “pubkey_hash”, “value”: “<hex>” }

• Script Hash: { “tag”: “script_hash”, “value”: “<hex>” }

• Always Abstain: { “tag”: “always_abstain” }

• Always No Confidence: { “tag”: “always_no_confidence” }

Parameters:¶

const cardano_drep_t *drep¶

[in] Pointer to a valid cardano_drep_t.

cardano_json_writer_t *writer¶

[in] Pointer to a valid cardano_json_writer_t.

Returns:¶

CARDANO_SUCCESS On success. CARDANO_ERROR_POINTER_IS_NULL If drep or writer is NULL. CARDANO_ERROR_MEMORY_ALLOCATION_FAILED If memory allocation fails. Other Any error propagated from nested writers.

size_t cardano_drep_get_string_size(const cardano_drep_t *drep)¶

Retrieves the size needed for the string representation (CIP-129) of a Cardano DRep.

This function calculates the size of the buffer required to hold the string representation of a cardano_drep_t object, including the null terminator. This size is necessary to ensure that the buffer allocated for converting the DRep to a string is sufficient.

Usage Example:

cardano_drep_t* drep = cardano_drep_new(...);
size_t required_size = cardano_drep_get_string_size(drep);

char* drep_str = (char*)malloc(required_size);

if (drep_str)
{
  cardano_error_t result = cardano_drep_to_string(drep, drep_str, required_size);
  if (result == CARDANO_SUCCESS)
  {
    printf("DRep: %s\n", drep_str);
  }
  free(drep_str);
}

// Clean up the drep object once done
cardano_drep_unref(&drep);

Parameters:¶

const cardano_drep_t *drep¶

[in] A constant pointer to the cardano_drep_t object for which the string size is being calculated. The object must not be NULL.

Returns:¶

The size in bytes needed to store the string representation of the DRep, including the null terminator. If the input DRep is NULL, the behavior is undefined.

cardano_error_t cardano_drep_to_string(const cardano_drep_t *drep, char *data, size_t size)¶

Converts a Cardano DRep into its string representation (CIP-129).

This function serializes the given cardano_drep_t object into a string format. The string is written to a user-provided buffer, and the size of this buffer must be adequate to hold the entire string, including the null terminator. The required size can be determined by calling cardano_drep_get_string_size.

Usage Example:

cardano_drep_t* drep = cardano_drep_new(...);
size_t required_size = cardano_drep_get_string_size(drep);
char* drep_str = (char*)malloc(required_size);

if (drep_str)
{
  cardano_error_t result = cardano_drep_to_string(drep, drep_str, required_size);
  if (result == CARDANO_SUCCESS)
  {
    printf("Address: %s\n", drep_str);
  }

  free(drep_str);
}

// Clean up the drep object once done
cardano_drep_unref(&drep);

Parameters:¶

const cardano_drep_t *drep¶

[in] A constant pointer to the cardano_drep_t object that is to be converted to a string. The object must not be NULL.

char *data¶

[out] A pointer to the buffer where the string representation of the drep will be written.

size_t size¶

[in] The size of the buffer pointed to by data. This size should be at least as large as the value returned by cardano_drep_get_string_size to ensure successful serialization.

Returns:¶

Returns CARDANO_SUCCESS if the conversion is successful. If the buffer is too small, returns CARDANO_ERROR_INSUFFICIENT_BUFFER_SIZE. If the drep or data is NULL, returns CARDANO_ERROR_POINTER_IS_NULL.

cardano_error_t cardano_drep_get_credential(cardano_drep_t *drep, cardano_credential_t **credential)¶

Retrieves the credential associated with a drep.

This function retrieves the credential associated with the given cardano_drep_t object. The retrieved credential is returned via the credential output parameter.

Usage Example:

cardano_drep_t* drep = ...;  // Assume drep is initialized here
cardano_credential_t* credential = NULL;

// Retrieve the credential
cardano_error_t result = cardano_drep_get_credential(drep, &credential);

if (result == CARDANO_SUCCESS && credential != NULL)
{
  // Use the credential

  // Once done, ensure to clean up and release the credential
  cardano_credential_unref(&credential);
}

cardano_drep_unref(&drep);

Parameters:¶

cardano_drep_t *drep¶

[in] A pointer to the cardano_drep_t object from which to retrieve the credential.

cardano_credential_t **credential¶

[out] A pointer to a pointer that will be set to the address of the retrieved cardano_credential_t object. The caller is responsible for managing the lifecycle of this credential. Specifically, once the credential is no longer needed, the caller must release it by calling cardano_credential_unref. Will be NULL if the drep is of type CARDANO_DREP_TYPE_ABSTAIN or CARDANO_DREP_TYPE_NO_CONFIDENCE.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the credential was successfully retrieved, or an appropriate error code indicating the failure reason.

cardano_error_t cardano_drep_set_credential(cardano_drep_t *drep, cardano_credential_t *credential)¶

Sets the credential associated with a drep.

This function sets the credential for the given cardano_drep_t object.

Usage Example:

cardano_drep_t* drep = ...;  // Assume drep is initialized here
cardano_credential_t* credential = ...;  // Assume credential is initialized here

// Set the credential
cardano_error_t result = cardano_drep_set_credential(drep, credential);

if (result == CARDANO_SUCCESS)
{
  // Credential was successfully set
}

// Clean up
cardano_drep_unref(&drep);
cardano_credential_unref(&credential);

Parameters:¶

cardano_drep_t *drep¶

[inout] A pointer to the cardano_drep_t object for which to set the credential.

cardano_credential_t *credential¶

[in] A pointer to the cardano_credential_t object to be associated with the drep. The credential must be properly initialized before being passed to this function. For CARDANO_DREP_TYPE_ABSTAIN and CARDANO_DREP_TYPE_NO_CONFIDENCE, this parameter must be NULL.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the credential was successfully set, or an appropriate error code indicating the failure reason.

cardano_error_t cardano_drep_get_type(const cardano_drep_t *drep, cardano_drep_type_t *type)¶

Retrieves the type of a drep.

This function gets the type of the given cardano_drep_t object.

Usage Example:

cardano_drep_t* drep = ...;  // Assume drep is initialized here
cardano_drep_type_t type;

// Get the drep type
cardano_error_t result = cardano_drep_get_type(drep, &type);

if (result == CARDANO_SUCCESS)
{
  // The type was successfully retrieved
}

// Clean up
cardano_drep_unref(&drep);

Parameters:¶

const cardano_drep_t *drep¶

[in] A constant pointer to the cardano_drep_t object.

cardano_drep_type_t *type¶

[out] A pointer to a cardano_drep_type_t variable where the type will be stored.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the type was successfully retrieved, or an appropriate error code indicating the failure reason.

cardano_error_t cardano_drep_set_type(cardano_drep_t *drep, cardano_drep_type_t type)¶

Sets the type of a drep.

This function sets the type of the given cardano_drep_t object.

Usage Example:

cardano_drep_t* drep = ...;  // Assume drep is initialized here
cardano_drep_type_t type = CARDANO_DREP_TYPE_KEY_HASH;

// Set the drep type
cardano_error_t result = cardano_drep_set_type(drep, type);

if (result == CARDANO_SUCCESS)
{
  // The type was successfully set
}

// Clean up
cardano_drep_unref(&drep);

Remark

If the type is set to CARDANO_DREP_TYPE_ABSTAIN or CARDANO_DREP_TYPE_NO_CONFIDENCE, the credential must be NULL.

Parameters:¶

cardano_drep_t *drep¶

[inout] A pointer to the cardano_drep_t object whose type is to be set.

cardano_drep_type_t type¶

[in] The cardano_drep_type_t value to set for the drep.

Returns:¶

cardano_error_t indicating the outcome of the operation. Returns CARDANO_SUCCESS if the type was successfully set, or an appropriate error code indicating the failure reason.

void cardano_drep_unref(cardano_drep_t **drep)¶

Decrements the reference count of a drep object.

This function is responsible for managing the lifecycle of a cardano_drep_t object by decreasing its reference count. When the reference count reaches zero, the drep is finalized; its associated resources are released, and its memory is deallocated.

Usage Example:

cardano_drep_t* drep = cardano_drep_new();

// Perform operations with the drep...

cardano_drep_unref(&drep);
// At this point, drep is NULL and cannot be used.

Note

After calling cardano_drep_unref, the pointer to the cardano_drep_t object will be set to NULL to prevent its reuse.

Parameters:¶

cardano_drep_t **drep¶

[inout] A pointer to the pointer of the drep object. This double indirection allows the function to set the caller’s pointer to NULL, avoiding dangling pointer issues after the object has been freed.

void cardano_drep_ref(cardano_drep_t *drep)¶

Increases the reference count of the cardano_drep_t object.

This function is used to manually increment the reference count of a drep object, indicating that another part of the code has taken ownership of it. This ensures the object remains allocated and valid until all owners have released their reference by calling cardano_drep_unref.

Usage Example:

// Assuming drep is a previously created drep object

cardano_drep_ref(drep);

// Now drep can be safely used elsewhere without worrying about premature deallocation

Note

Always ensure that for every call to cardano_drep_ref there is a corresponding call to cardano_drep_unref to prevent memory leaks.

Parameters:¶

cardano_drep_t *drep¶

A pointer to the drep object whose reference count is to be incremented.

size_t cardano_drep_refcount(const cardano_drep_t *drep)¶

Retrieves the current reference count of the cardano_drep_t object.

This function returns the number of active references to a drep object. It’s useful for debugging purposes or managing the lifecycle of the object in complex scenarios.

Usage Example:

// Assuming drep is a previously created drep object

size_t ref_count = cardano_drep_refcount(drep);

printf("Reference count: %zu\n", ref_count);

Warning

This function does not account for transitive references. A transitive reference occurs when an object holds a reference to another object, rather than directly to the cardano_drep_t. As such, the reported count may not fully represent the total number of conceptual references in cases where such transitive relationships exist.

Parameters:¶

const cardano_drep_t *drep¶

A pointer to the drep object whose reference count is queried. The object must not be NULL.

Returns:¶

The number of active references to the specified drep object. If the object is properly managed (i.e., every cardano_drep_ref call is matched with a cardano_drep_unref call), this count should reach zero right before the object is deallocated.

void cardano_drep_set_last_error(cardano_drep_t *drep, const char *message)¶

Sets the last error message for a given drep object.

Records an error message in the drep’s last_error buffer, overwriting any existing message. This is useful for storing descriptive error information that can be later retrieved. The message is truncated if it exceeds the buffer’s capacity.

Note

The error message is limited to 1023 characters, including the null terminator, due to the fixed size of the last_error buffer.

Parameters:¶

cardano_drep_t *drep¶

[in] A pointer to the cardano_drep_t instance whose last error message is to be set. If NULL, the function does nothing.

const char *message¶

[in] A null-terminated string containing the error message. If NULL, the drep’s last_error is set to an empty string, indicating no error.

const char *cardano_drep_get_last_error(const cardano_drep_t *drep)¶

Retrieves the last error message recorded for a specific drep.

This function returns a pointer to the null-terminated string containing the last error message set by cardano_drep_set_last_error for the given drep. If no error message has been set, or if the last_error buffer was explicitly cleared, an empty string is returned, indicating no error.

Note

The returned string points to internal storage within the object and must not be modified by the caller. The string remains valid until the next call to cardano_drep_set_last_error for the same drep, or until the drep is deallocated.

Parameters:¶

const cardano_drep_t *drep¶

[in] A pointer to the cardano_drep_t instance whose last error message is to be retrieved. If the drep is NULL, the function returns a generic error message indicating the null drep.

Returns:¶

A pointer to a null-terminated string containing the last error message for the specified drep. If the drep is NULL, “Object is NULL.” is returned to indicate the error.