Protocol Communication

Overview

The Protocol Communication (protocomm) component manages secure sessions and provides the framework for multiple transports. The application can also use the protocomm layer directly to have application-specific extensions for the provisioning or non-provisioning use cases.

Following features are available for provisioning:

Communication security at the application level

protocomm_security0 (no security)

protocomm_security1 (Curve25519 key exchange + AES-CTR encryption/decryption)

protocomm_security2 (SRP6a-based key exchange + AES-GCM encryption/decryption)

Proof-of-possession (support with protocomm_security1 only)

Salt and Verifier (support with protocomm_security2 only)

Protocomm internally uses protobuf (protocol buffers) for secure session establishment. Users can choose to implement their own security (even without using protobuf). Protocomm can also be used without any security layer.

Protocomm provides the framework for various transports:

Bluetooth LE
Console, in which case the handler invocation is automatically taken care of on the device side. See Transport Examples below for code snippets.

Note that for protocomm_security1 and protocomm_security2, the client still needs to establish sessions by performing the two-way handshake.

Enabling Protocomm Security Version

The protocomm component provides a project configuration menu to enable/disable support of respective security versions. The respective configuration options are as follows:

Support protocomm_security0, with no security: CONFIG_ESP_PROTOCOMM_SUPPORT_SECURITY_VERSION_0, this option is enabled by default.

Support protocomm_security1 with Curve25519 key exchange + AES-CTR encryption/decryption: CONFIG_ESP_PROTOCOMM_SUPPORT_SECURITY_VERSION_1, this option is enabled by default.

Support protocomm_security2 with SRP6a-based key exchange + AES-GCM encryption/decryption: CONFIG_ESP_PROTOCOMM_SUPPORT_SECURITY_VERSION_2.

Note

Enabling multiple security versions at once offers the ability to control them dynamically but also increases the firmware size.

Bluetooth LE Transport Example with Security 0

For sample usage, see wifi_provisioning/src/scheme_ble.c.

/* The example function for launching a secure protocomm instance over Bluetooth LE. */
protocomm_t *start_pc()
{
    protocomm_t *pc = protocomm_new();

    /* Endpoint UUIDs */
    protocomm_ble_name_uuid_t nu_lookup_table[] = {
        {"security_endpoint", 0xFF51},
        {"echo_req_endpoint", 0xFF52}
    };

    /* Config for protocomm_ble_start(). */
    protocomm_ble_config_t config = {
        .service_uuid = {
            /* LSB <---------------------------------------
            * ---------------------------------------> MSB */
            0xfb, 0x34, 0x9b, 0x5f, 0x80, 0x00, 0x00, 0x80,
            0x00, 0x10, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00,
        },
        .nu_lookup_count = sizeof(nu_lookup_table)/sizeof(nu_lookup_table[0]),
        .nu_lookup = nu_lookup_table
    };

    /* Start protocomm layer on top of Bluetooth LE. */
    protocomm_ble_start(pc, &config);

    /* For protocomm_security0, Proof of Possession is not used, and can be kept NULL. */
    protocomm_set_security(pc, "security_endpoint", &protocomm_security0, NULL);
    protocomm_add_endpoint(pc, "echo_req_endpoint", echo_req_handler, NULL);
    return pc;
}

/* The example function for stopping a protocomm instance. */
void stop_pc(protocomm_t *pc)
{
    protocomm_remove_endpoint(pc, "echo_req_endpoint");
    protocomm_unset_security(pc, "security_endpoint");

    /* Stop the Bluetooth LE protocomm service. */
    protocomm_ble_stop(pc);

    protocomm_delete(pc);
}

API Reference

Header File

components/protocomm/include/common/protocomm.h
This header file can be included with:
#include "protocomm.h"
This header file is a part of the API provided by the protocomm component. To declare that your component depends on protocomm, add the following to your CMakeLists.txt:
REQUIRES protocomm
or
PRIV_REQUIRES protocomm

Functions

protocomm_t *protocomm_new(void)

Create a new protocomm instance.

This API will return a new dynamically allocated protocomm instance with all elements of the protocomm_t structure initialized to NULL.

Returns

protocomm_t* : On success
NULL : No memory for allocating new instance

void protocomm_delete(protocomm_t *pc)

Delete a protocomm instance.

This API will deallocate a protocomm instance that was created using protocomm_new().

Parameters: pc -- [in] Pointer to the protocomm instance to be deleted

esp_err_t protocomm_add_endpoint(protocomm_t *pc, const char *ep_name, protocomm_req_handler_t h, void *priv_data)

Add endpoint request handler for a protocomm instance.

This API will bind an endpoint handler function to the specified endpoint name, along with any private data that needs to be pass to the handler at the time of call.

Note

An endpoint must be bound to a valid protocomm instance, created using protocomm_new().
This function internally calls the registered add_endpoint() function of the selected transport which is a member of the protocomm_t instance structure.

Parameters

pc -- [in] Pointer to the protocomm instance
ep_name -- [in] Endpoint identifier(name) string
h -- [in] Endpoint handler function
priv_data -- [in] Pointer to private data to be passed as a parameter to the handler function on call. Pass NULL if not needed.

Returns

ESP_OK : Success
ESP_FAIL : Error adding endpoint / Endpoint with this name already exists
ESP_ERR_NO_MEM : Error allocating endpoint resource
ESP_ERR_INVALID_ARG : Null instance/name/handler arguments

esp_err_t protocomm_remove_endpoint(protocomm_t *pc, const char *ep_name)

Remove endpoint request handler for a protocomm instance.

This API will remove a registered endpoint handler identified by an endpoint name.

Note

This function internally calls the registered remove_endpoint() function which is a member of the protocomm_t instance structure.

Parameters

pc -- [in] Pointer to the protocomm instance
ep_name -- [in] Endpoint identifier(name) string

Returns

ESP_OK : Success
ESP_ERR_NOT_FOUND : Endpoint with specified name doesn't exist
ESP_ERR_INVALID_ARG : Null instance/name arguments

esp_err_t protocomm_open_session(protocomm_t *pc, uint32_t session_id)

Allocates internal resources for new transport session.

Note

An endpoint must be bound to a valid protocomm instance, created using protocomm_new().

Parameters

pc -- [in] Pointer to the protocomm instance
session_id -- [in] Unique ID for a communication session

Returns

ESP_OK : Request handled successfully
ESP_ERR_NO_MEM : Error allocating internal resource
ESP_ERR_INVALID_ARG : Null instance/name arguments

esp_err_t protocomm_close_session(protocomm_t *pc, uint32_t session_id)

Frees internal resources used by a transport session.

Note

An endpoint must be bound to a valid protocomm instance, created using protocomm_new().

Parameters

pc -- [in] Pointer to the protocomm instance
session_id -- [in] Unique ID for a communication session

Returns

ESP_OK : Request handled successfully
ESP_ERR_INVALID_ARG : Null instance/name arguments

esp_err_t protocomm_req_handle(protocomm_t *pc, const char *ep_name, uint32_t session_id, const uint8_t *inbuf, ssize_t inlen, uint8_t **outbuf, ssize_t *outlen)

Calls the registered handler of an endpoint session for processing incoming data and generating the response.

Note

An endpoint must be bound to a valid protocomm instance, created using protocomm_new().
Resulting output buffer must be deallocated by the caller.

Parameters

pc -- [in] Pointer to the protocomm instance
ep_name -- [in] Endpoint identifier(name) string
session_id -- [in] Unique ID for a communication session
inbuf -- [in] Input buffer contains input request data which is to be processed by the registered handler
inlen -- [in] Length of the input buffer
outbuf -- [out] Pointer to internally allocated output buffer, where the resulting response data output from the registered handler is to be stored
outlen -- [out] Buffer length of the allocated output buffer

Returns

ESP_OK : Request handled successfully
ESP_FAIL : Internal error in execution of registered handler
ESP_ERR_NO_MEM : Error allocating internal resource
ESP_ERR_NOT_FOUND : Endpoint with specified name doesn't exist
ESP_ERR_INVALID_ARG : Null instance/name arguments

esp_err_t protocomm_set_security(protocomm_t *pc, const char *ep_name, const protocomm_security_t *sec, const void *sec_params)

Add endpoint security for a protocomm instance.

This API will bind a security session establisher to the specified endpoint name, along with any proof of possession that may be required for authenticating a session client.

Note

An endpoint must be bound to a valid protocomm instance, created using protocomm_new().
The choice of security can be any protocomm_security_t instance. Choices protocomm_security0 and protocomm_security1 and protocomm_security2 are readily available.

Parameters

pc -- [in] Pointer to the protocomm instance
ep_name -- [in] Endpoint identifier(name) string
sec -- [in] Pointer to endpoint security instance
sec_params -- [in] Pointer to security params (NULL if not needed) The pointer should contain the security params struct of appropriate security version. For protocomm security version 1 and 2 sec_params should contain pointer to struct of type protocomm_security1_params_t and protocmm_security2_params_t respectively. The contents of this pointer must be valid till the security session has been running and is not closed.

Returns

ESP_OK : Success
ESP_FAIL : Error adding endpoint / Endpoint with this name already exists
ESP_ERR_INVALID_STATE : Security endpoint already set
ESP_ERR_NO_MEM : Error allocating endpoint resource
ESP_ERR_INVALID_ARG : Null instance/name/handler arguments

esp_err_t protocomm_unset_security(protocomm_t *pc, const char *ep_name)

Remove endpoint security for a protocomm instance.

This API will remove a registered security endpoint identified by an endpoint name.

Parameters

pc -- [in] Pointer to the protocomm instance
ep_name -- [in] Endpoint identifier(name) string

Returns

ESP_OK : Success
ESP_ERR_NOT_FOUND : Endpoint with specified name doesn't exist
ESP_ERR_INVALID_ARG : Null instance/name arguments

esp_err_t protocomm_set_version(protocomm_t *pc, const char *ep_name, const char *version)

Set endpoint for version verification.

This API can be used for setting an application specific protocol version which can be verified by clients through the endpoint.

Note

An endpoint must be bound to a valid protocomm instance, created using protocomm_new().

Parameters

pc -- [in] Pointer to the protocomm instance
ep_name -- [in] Endpoint identifier(name) string
version -- [in] Version identifier(name) string

Returns

ESP_OK : Success
ESP_FAIL : Error adding endpoint / Endpoint with this name already exists
ESP_ERR_INVALID_STATE : Version endpoint already set
ESP_ERR_NO_MEM : Error allocating endpoint resource
ESP_ERR_INVALID_ARG : Null instance/name/handler arguments

esp_err_t protocomm_unset_version(protocomm_t *pc, const char *ep_name)

Remove version verification endpoint from a protocomm instance.

This API will remove a registered version endpoint identified by an endpoint name.

Parameters

pc -- [in] Pointer to the protocomm instance
ep_name -- [in] Endpoint identifier(name) string

Returns

ESP_OK : Success
ESP_ERR_NOT_FOUND : Endpoint with specified name doesn't exist
ESP_ERR_INVALID_ARG : Null instance/name arguments

Type Definitions

typedef esp_err_t (*protocomm_req_handler_t)(uint32_t session_id, const uint8_t *inbuf, ssize_t inlen, uint8_t **outbuf, ssize_t *outlen, void *priv_data): Function prototype for protocomm endpoint handler.

typedef struct protocomm protocomm_t: This structure corresponds to a unique instance of protocomm returned when the API protocomm_new() is called. The remaining Protocomm APIs require this object as the first parameter.

Note

Structure of the protocomm object is kept private

Header File

components/protocomm/include/security/protocomm_security.h
This header file can be included with:
#include "protocomm_security.h"
This header file is a part of the API provided by the protocomm component. To declare that your component depends on protocomm, add the following to your CMakeLists.txt:
REQUIRES protocomm
or
PRIV_REQUIRES protocomm

Structures

struct protocomm_security1_params

Protocomm Security 1 parameters: Proof Of Possession.

Public Members

const uint8_t *data: Pointer to buffer containing the proof of possession data

uint16_t len: Length (in bytes) of the proof of possession data

struct protocomm_security2_params

Protocomm Security 2 parameters: Salt and Verifier.

Public Members

const char *salt: Pointer to the buffer containing the salt

uint16_t salt_len: Length (in bytes) of the salt

const char *verifier: Pointer to the buffer containing the verifier

uint16_t verifier_len: Length (in bytes) of the verifier

struct protocomm_security

Protocomm security object structure.

The member functions are used for implementing secure protocomm sessions.

Note

This structure should not have any dynamic members to allow re-entrancy

Public Members

int ver: Unique version number of security implementation

esp_err_t (*init)(protocomm_security_handle_t *handle): Function for initializing/allocating security infrastructure

esp_err_t (*cleanup)(protocomm_security_handle_t handle): Function for deallocating security infrastructure

esp_err_t (*new_transport_session)(protocomm_security_handle_t handle, uint32_t session_id): Starts new secure transport session with specified ID

esp_err_t (*close_transport_session)(protocomm_security_handle_t handle, uint32_t session_id): Closes a secure transport session with specified ID

esp_err_t (*security_req_handler)(protocomm_security_handle_t handle, const void *sec_params, uint32_t session_id, const uint8_t *inbuf, ssize_t inlen, uint8_t **outbuf, ssize_t *outlen, void *priv_data): Handler function for authenticating connection request and establishing secure session

esp_err_t (*encrypt)(protocomm_security_handle_t handle, uint32_t session_id, const uint8_t *inbuf, ssize_t inlen, uint8_t **outbuf, ssize_t *outlen): Function which implements the encryption algorithm

esp_err_t (*decrypt)(protocomm_security_handle_t handle, uint32_t session_id, const uint8_t *inbuf, ssize_t inlen, uint8_t **outbuf, ssize_t *outlen): Function which implements the decryption algorithm

Type Definitions

typedef struct protocomm_security1_params protocomm_security1_params_t: Protocomm Security 1 parameters: Proof Of Possession.

typedef protocomm_security1_params_t protocomm_security_pop_t

typedef struct protocomm_security2_params protocomm_security2_params_t: Protocomm Security 2 parameters: Salt and Verifier.

typedef void *protocomm_security_handle_t

typedef struct protocomm_security protocomm_security_t

Protocomm security object structure.

The member functions are used for implementing secure protocomm sessions.

Note

This structure should not have any dynamic members to allow re-entrancy

Enumerations

enum protocomm_security_session_event_t

Events generated by the protocomm security layer.

These events are generated while establishing secured session.

Values:

enumerator PROTOCOMM_SECURITY_SESSION_SETUP_OK: Secured session established successfully

enumerator PROTOCOMM_SECURITY_SESSION_INVALID_SECURITY_PARAMS: Received invalid (NULL) security parameters (username / client public-key)

enumerator PROTOCOMM_SECURITY_SESSION_CREDENTIALS_MISMATCH: Received incorrect credentials (username / PoP)

Header File

components/protocomm/include/security/protocomm_security0.h
This header file can be included with:
#include "protocomm_security0.h"
This header file is a part of the API provided by the protocomm component. To declare that your component depends on protocomm, add the following to your CMakeLists.txt:
REQUIRES protocomm
or
PRIV_REQUIRES protocomm

Header File

components/protocomm/include/security/protocomm_security1.h
This header file can be included with:
#include "protocomm_security1.h"
This header file is a part of the API provided by the protocomm component. To declare that your component depends on protocomm, add the following to your CMakeLists.txt:
REQUIRES protocomm
or
PRIV_REQUIRES protocomm

Header File

components/protocomm/include/security/protocomm_security2.h
This header file can be included with:
#include "protocomm_security2.h"
This header file is a part of the API provided by the protocomm component. To declare that your component depends on protocomm, add the following to your CMakeLists.txt:
REQUIRES protocomm
or
PRIV_REQUIRES protocomm

Header File

components/protocomm/include/crypto/srp6a/esp_srp.h
This header file can be included with:
#include "esp_srp.h"
This header file is a part of the API provided by the protocomm component. To declare that your component depends on protocomm, add the following to your CMakeLists.txt:
REQUIRES protocomm
or
PRIV_REQUIRES protocomm

Functions

esp_srp_handle_t *esp_srp_init(esp_ng_type_t ng)

Initialize srp context for given NG type.

Note

the handle gets freed with esp_srp_free

Parameters: ng -- NG type given by esp_ng_type_t
Returns: esp_srp_handle_t* srp handle

void esp_srp_free(esp_srp_handle_t *hd)

free esp_srp_context

Parameters: hd -- handle to be free

esp_err_t esp_srp_srv_pubkey(esp_srp_handle_t *hd, const char *username, int username_len, const char *pass, int pass_len, int salt_len, char **bytes_B, int *len_B, char **bytes_salt)

Returns B (pub key) and salt. [Step2.b].

Note

*bytes_B MUST NOT BE FREED BY THE CALLER

Note

*bytes_salt MUST NOT BE FREE BY THE CALLER

Parameters

hd -- esp_srp handle
username -- Username not expected NULL terminated
username_len -- Username length
pass -- Password not expected to be NULL terminated
pass_len -- Pasword length
salt_len -- Salt length
bytes_B -- Public Key returned
len_B -- Length of the public key
bytes_salt -- Salt bytes generated

Returns

esp_err_t ESP_OK on success, appropriate error otherwise

esp_err_t esp_srp_gen_salt_verifier(const char *username, int username_len, const char *pass, int pass_len, char **bytes_salt, int salt_len, char **verifier, int *verifier_len)

Generate salt-verifier pair, given username, password and salt length.

Note

if API has returned ESP_OK, salt and verifier generated need to be freed by caller

Note

Usually, username and password are not saved on the device. Rather salt and verifier are generated outside the device and are embedded. this covenience API can be used to generate salt and verifier on the fly for development use case. OR for devices which intentionally want to generate different password each time and can send it to the client securely. e.g., a device has a display and it shows the pin

Parameters

username -- [in] username
username_len -- [in] length of the username
pass -- [in] password
pass_len -- [in] length of the password
bytes_salt -- [out] generated salt on successful generation, or NULL
salt_len -- [in] salt length
verifier -- [out] generated verifier on successful generation, or NULL
verifier_len -- [out] length of the generated verifier

Returns

esp_err_t ESP_OK on success, appropriate error otherwise

esp_err_t esp_srp_set_salt_verifier(esp_srp_handle_t *hd, const char *salt, int salt_len, const char *verifier, int verifier_len)

Set the Salt and Verifier pre-generated for a given password. This should be used only if the actual password is not available. The public key can then be generated using esp_srp_srv_pubkey_from_salt_verifier() and not esp_srp_srv_pubkey()

Parameters

hd -- esp_srp_handle
salt -- pre-generated salt bytes
salt_len -- length of the salt bytes
verifier -- pre-generated verifier
verifier_len -- length of the verifier bytes

Returns

esp_err_t ESP_OK on success, appropriate error otherwise

esp_err_t esp_srp_srv_pubkey_from_salt_verifier(esp_srp_handle_t *hd, char **bytes_B, int *len_B)

Returns B (pub key)[Step2.b] when the salt and verifier are set using esp_srp_set_salt_verifier()

Note

*bytes_B MUST NOT BE FREED BY THE CALLER

Parameters

hd -- esp_srp handle
bytes_B -- Key returned to the called
len_B -- Length of the key returned

Returns

esp_err_t ESP_OK on success, appropriate error otherwise

esp_err_t esp_srp_get_session_key(esp_srp_handle_t *hd, char *bytes_A, int len_A, char **bytes_key, uint16_t *len_key)

Get session key in *bytes_key given by len in *len_key. [Step2.c].

This calculated session key is used for further communication given the proofs are exchanged/authenticated with esp_srp_exchange_proofs

Note

*bytes_key MUST NOT BE FREED BY THE CALLER

Parameters

hd -- esp_srp handle
bytes_A -- Private Key
len_A -- Private Key length
bytes_key -- Key returned to the caller
len_key -- length of the key in *bytes_key

Returns

esp_err_t ESP_OK on success, appropriate error otherwise

esp_err_t esp_srp_exchange_proofs(esp_srp_handle_t *hd, char *username, uint16_t username_len, char *bytes_user_proof, char *bytes_host_proof)

Complete the authentication. If this step fails, the session_key exchanged should not be used.

This is the final authentication step in SRP algorithm [Step4.1, Step4.b, Step4.c]

Parameters

hd -- esp_srp handle
username -- Username not expected NULL terminated
username_len -- Username length
bytes_user_proof -- param in
bytes_host_proof -- parameter out (should be SHA512_DIGEST_LENGTH) bytes in size

Returns

esp_err_t ESP_OK if user's proof is ok and subsequently bytes_host_proof is populated with our own proof.

Type Definitions

typedef struct esp_srp_handle esp_srp_handle_t

esp_srp handle as the result of esp_srp_init

The handle is returned by esp_srp_init on successful init. It is then passed for subsequent API calls as an argument. esp_srp_free can be used to clean up the handle. After esp_srp_free the handle becomes invalid.

Enumerations

enum esp_ng_type_t

Large prime+generator to be used for the algorithm.

Values:

enumerator ESP_NG_3072

Header File

components/protocomm/include/transports/protocomm_httpd.h
This header file can be included with:
#include "protocomm_httpd.h"
This header file is a part of the API provided by the protocomm component. To declare that your component depends on protocomm, add the following to your CMakeLists.txt:
REQUIRES protocomm
or
PRIV_REQUIRES protocomm

Functions

esp_err_t protocomm_httpd_start(protocomm_t *pc, const protocomm_httpd_config_t *config)

Start HTTPD protocomm transport.

This API internally creates a framework to allow endpoint registration and security configuration for the protocomm.

Note

This is a singleton. ie. Protocomm can have multiple instances, but only one instance can be bound to an HTTP transport layer.

Parameters

pc -- [in] Protocomm instance pointer obtained from protocomm_new()
config -- [in] Pointer to config structure for initializing HTTP server

Returns

ESP_OK : Success
ESP_ERR_INVALID_ARG : Null arguments
ESP_ERR_NOT_SUPPORTED : Transport layer bound to another protocomm instance
ESP_ERR_INVALID_STATE : Transport layer already bound to this protocomm instance
ESP_ERR_NO_MEM : Memory allocation for server resource failed
ESP_ERR_HTTPD_* : HTTP server error on start

esp_err_t protocomm_httpd_stop(protocomm_t *pc)

Stop HTTPD protocomm transport.

This API cleans up the HTTPD transport protocomm and frees all the handlers registered with the protocomm.

Parameters

pc -- [in] Same protocomm instance that was passed to protocomm_httpd_start()

Returns

ESP_OK : Success
ESP_ERR_INVALID_ARG : Null / incorrect protocomm instance pointer

Unions

union protocomm_httpd_config_data_t

#include <protocomm_httpd.h>

Protocomm HTTPD Configuration Data

Public Members

void *handle: HTTP Server Handle, if ext_handle_provided is set to true

protocomm_http_server_config_t config: HTTP Server Configuration, if a server is not already active

Structures

struct protocomm_http_server_config_t

Config parameters for protocomm HTTP server.

Public Members

uint16_t port: Port on which the HTTP server will listen

size_t stack_size: Stack size of server task, adjusted depending upon stack usage of endpoint handler

unsigned task_priority: Priority of server task

struct protocomm_httpd_config_t

Config parameters for protocomm HTTP server.

Public Members

bool ext_handle_provided: Flag to indicate of an external HTTP Server Handle has been provided. In such as case, protocomm will use the same HTTP Server and not start a new one internally.

protocomm_httpd_config_data_t data: Protocomm HTTPD Configuration Data

Macros

PROTOCOMM_HTTPD_DEFAULT_CONFIG()

Header File

components/protocomm/include/transports/protocomm_ble.h
This header file can be included with:
#include "protocomm_ble.h"
This header file is a part of the API provided by the protocomm component. To declare that your component depends on protocomm, add the following to your CMakeLists.txt:
REQUIRES protocomm
or
PRIV_REQUIRES protocomm

Functions

esp_err_t protocomm_ble_start(protocomm_t *pc, const protocomm_ble_config_t *config)

Start Bluetooth Low Energy based transport layer for provisioning.

Initialize and start required BLE service for provisioning. This includes the initialization for characteristics/service for BLE.

Parameters

pc -- [in] Protocomm instance pointer obtained from protocomm_new()
config -- [in] Pointer to config structure for initializing BLE

Returns

ESP_OK : Success
ESP_FAIL : Simple BLE start error
ESP_ERR_NO_MEM : Error allocating memory for internal resources
ESP_ERR_INVALID_STATE : Error in ble config
ESP_ERR_INVALID_ARG : Null arguments

esp_err_t protocomm_ble_stop(protocomm_t *pc)

Stop Bluetooth Low Energy based transport layer for provisioning.

Stops service/task responsible for BLE based interactions for provisioning

Note

You might want to optionally reclaim memory from Bluetooth. Refer to the documentation of esp_bt_mem_release in that case.

Parameters

pc -- [in] Same protocomm instance that was passed to protocomm_ble_start()

Returns

ESP_OK : Success
ESP_FAIL : Simple BLE stop error
ESP_ERR_INVALID_ARG : Null / incorrect protocomm instance

Structures

struct name_uuid

This structure maps handler required by protocomm layer to UUIDs which are used to uniquely identify BLE characteristics from a smartphone or a similar client device.

Public Members

const char *name: Name of the handler, which is passed to protocomm layer

uint16_t uuid: UUID to be assigned to the BLE characteristic which is mapped to the handler

struct protocomm_ble_event_t

Structure for BLE events in Protocomm.

Public Members

uint16_t evt_type: This field indicates the type of BLE event that occurred.

uint16_t conn_handle: The handle of the relevant connection.

uint16_t conn_status: The status of the connection attempt; o 0: the connection was successfully established. o BLE host error code: the connection attempt failed for the specified reason.

uint16_t disconnect_reason: Return code indicating the reason for the disconnect.

struct protocomm_ble_config

Config parameters for protocomm BLE service.

Public Members

char device_name[MAX_BLE_DEVNAME_LEN + 1]: BLE device name being broadcast at the time of provisioning

uint8_t service_uuid[BLE_UUID128_VAL_LENGTH]: 128 bit UUID of the provisioning service

uint8_t *manufacturer_data: BLE device manufacturer data pointer in advertisement

ssize_t manufacturer_data_len: BLE device manufacturer data length in advertisement

ssize_t nu_lookup_count: Number of entries in the Name-UUID lookup table

protocomm_ble_name_uuid_t *nu_lookup: Pointer to the Name-UUID lookup table

unsigned ble_bonding: BLE bonding

unsigned ble_sm_sc: BLE security flag

unsigned ble_link_encryption: BLE security flag

uint8_t *ble_addr: BLE address

unsigned ble_notify: BLE characteristic notify flag

Macros

MAX_BLE_DEVNAME_LEN: BLE device name cannot be larger than this value 31 bytes (max scan response size) - 1 byte (length) - 1 byte (type) = 29 bytes

BLE_UUID128_VAL_LENGTH

MAX_BLE_MANUFACTURER_DATA_LEN: Theoretically, the limit for max manufacturer length remains same as BLE device name i.e. 31 bytes (max scan response size) - 1 byte (length) - 1 byte (type) = 29 bytes However, manufacturer data goes along with BLE device name in scan response. So, it is important to understand the actual length should be smaller than (29 - (BLE device name length) - 2).

BLE_ADDR_LEN

Type Definitions

typedef struct name_uuid protocomm_ble_name_uuid_t: This structure maps handler required by protocomm layer to UUIDs which are used to uniquely identify BLE characteristics from a smartphone or a similar client device.

typedef struct protocomm_ble_config protocomm_ble_config_t: Config parameters for protocomm BLE service.

Enumerations

enum protocomm_transport_ble_event_t

Events generated by BLE transport.

These events are generated when the BLE transport is paired and disconnected.

Values:

enumerator PROTOCOMM_TRANSPORT_BLE_CONNECTED

enumerator PROTOCOMM_TRANSPORT_BLE_DISCONNECTED

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