Protocols
Mbed TLS
For ESP-IDF v5.0, Mbed TLS has been updated from v2.x to v3.1.0.
For more details about Mbed TLS’s migration from version 2.x to version 3.0 or greater, please refer to the official guide.
Breaking Changes (Summary)
Most structure fields are now private
Direct access to fields of structures (
struct
types) declared in public headers is no longer supported.Appropriate accessor functions (getter/setter) must be used for the same. A temporary workaround would be to use
MBEDTLS_PRIVATE
macro (not recommended).For more details, refer to the official guide.
SSL
Removed support for TLS 1.0, 1.1, and DTLS 1.0
Removed support for SSL 3.0
Deprecated Functions Were Removed from Cryptography Modules
The functions
mbedtls_*_ret()
(related to MD, SHA, RIPEMD, RNG, HMAC modules) was renamed to replace the corresponding functions without_ret
appended and updated return value.For more details, refer to the official guide.
Deprecated Config Options
Following are some of the important config options deprecated by this update. The configs related to and/or dependent on these have also been deprecated.
MBEDTLS_SSL_PROTO_SSL3
: Support for SSL 3.0MBEDTLS_SSL_PROTO_TLS1
: Support for TLS 1.0MBEDTLS_SSL_PROTO_TLS1_1
: Support for TLS 1.1MBEDTLS_SSL_PROTO_DTLS
: Support for DTLS 1.1 (Only DTLS 1.2 is supported now)MBEDTLS_DES_C
: Support for 3DES ciphersuitesMBEDTLS_RC4_MODE
: Support for RC4-based ciphersuites
Note
This list includes only major options configurable through idf.py menuconfig
. For more details on deprecated options, refer to the official guide.
Miscellaneous
Disabled Diffie-Hellman Key Exchange Modes
The Diffie-Hellman Key Exchange modes have now been disabled by default due to security risks (see warning text here). Related configs are given below:
MBEDTLS_DHM_C
: Support for the Diffie-Hellman-Merkle moduleMBEDTLS_KEY_EXCHANGE_DHE_PSK
: Support for Diffie-Hellman PSK (pre-shared-key) TLS authentication modesMBEDTLS_KEY_EXCHANGE_DHE_RSA
: Support for cipher suites with the prefixTLS-DHE-RSA-WITH-
Note
During the initial step of the handshake (i.e. client_hello
), the server selects a cipher from the list that the client publishes. As the DHE_PSK/DHE_RSA ciphers have now been disabled by the above change, the server would fall back to an alternative cipher; if in a rare case, it does not support any other cipher, the handshake would fail. To retrieve the list of ciphers supported by the server, one must attempt to connect with the server with a specific cipher from the client-side. Few utilities can help do this, e.g. sslscan
.
Remove certs
Module from X509 Library
The
mbedtls/certs.h
header is no longer available in mbedtls 3.1. Most applications can safely remove it from the list of includes.
Breaking Change for esp_crt_bundle_set
API
The
esp_crt_bundle_set()
API now requires one additional argument namedbundle_size
. The return type of the API has also been changed toesp_err_t
fromvoid
.
Breaking Change for esp_ds_rsa_sign
API
The
esp_ds_rsa_sign()
API now requires one less argument. The argumentmode
is no longer required.
HTTPS Server
Breaking Changes (Summary)
Names of variables holding different certs in httpd_ssl_config_t
structure have been updated.
httpd_ssl_config::servercert
variable inherits role ofcacert_pem
variable.httpd_ssl_config::servercert_len
variable inherits role ofcacert_len
variablehttpd_ssl_config::cacert_pem
variable inherits role ofclient_verify_cert_pem
variablehttpd_ssl_config::cacert_len
variable inherits role ofclient_verify_cert_len
variable
The return type of the httpd_ssl_stop()
API has been changed to esp_err_t
from void
.
ESP HTTPS OTA
Breaking Changes (Summary)
The function
esp_https_ota()
now requires pointer toesp_https_ota_config_t
as argument instead of pointer toesp_http_client_config_t
.
ESP-TLS
Breaking Changes (Summary)
esp_tls_t
Structure is Now Private
The esp_tls_t
has now been made completely private. You cannot access its internal structures directly. Any necessary data that needs to be obtained from the ESP-TLS handle can be done through respective getter/setter functions. If there is a requirement of a specific getter/setter function, please raise an issue on ESP-IDF.
The list of newly added getter/setter function is as as follows:
esp_tls_get_ssl_context()
- Obtain the ssl context of the underlying ssl stack from the ESP-TLS handle.
Function Deprecations And Recommended Alternatives
Following table summarizes the deprecated functions removed and their alternatives to be used from ESP-IDF v5.0 onwards.
Deprecated Function |
Alternative |
---|---|
|
|
|
The function
esp_tls_conn_http_new()
has now been termed as deprecated. Please use the alternative functionesp_tls_conn_http_new_sync()
(or its asynchronousesp_tls_conn_http_new_async()
). Note that the alternatives need an additional parameteresp_tls_t
, which has to be initialized using theesp_tls_init()
function.
HTTP Server
Breaking Changes (Summary)
http_server.h
header is no longer available inesp_http_server
. Please useesp_http_server.h
instead.
ESP HTTP Client
Breaking Changes (Summary)
The functions
esp_http_client_read()
andesp_http_client_fetch_headers()
now return an additional return value-ESP_ERR_HTTP_EAGAIN
for timeout errors - call timed-out before any data was ready.
TCP Transport
Breaking Changes (Summary)
The function
esp_transport_read()
now returns0
for a connection timeout and< 0
for other errors. Please referesp_tcp_transport_err_t
for all possible return values.
MQTT Client
Breaking Changes (Summary)
esp_mqtt_client_config_t
have all fields grouped in sub structs.
Most common configurations are listed below:
Broker address now is set in
esp_mqtt_client_config_t::broker::address::uri
Security related to broker verification in
esp_mqtt_client_config_t::broker::verification
Client username is set in
esp_mqtt_client_config_t::credentials::username
esp_mqtt_client_config_t
no longer supports theuser_context
field. Please useesp_mqtt_client_register_event()
instead for registering an event handler; the last argumentevent_handler_arg
can be used to pass user context to the handler.
ESP-Modbus
Breaking Changes (Summary)
The ESP-IDF component freemodbus
has been removed from ESP-IDF and is supported as a separate component. Additional information for the ESP-Modbus
component can be found in the separate repository:
The main
component folder of the new application shall include the component manager manifest file idf_component.yml
as in the example below:
dependencies:
espressif/esp-modbus:
version: "^1.0"
The esp-modbus
component can be found in component manager registry. Refer to component manager documentation for more information on how to set up the component manager.
For applications targeting v4.x releases of ESP-IDF that need to use new esp-modbus
component, adding the component manager manifest file idf_component.yml
will be sufficient to pull in the new component. However, users should also exclude the legacy freemodbus
component from the build. This can be achieved using the statement below in the project’s CMakeLists.txt
:
set(EXCLUDE_COMPONENTS freemodbus)