esp-idf/examples/protocols/esp_http_client

Supported Targets	ESP32	ESP32-C2	ESP32-C3	ESP32-C5	ESP32-C6	ESP32-C61	ESP32-H2	ESP32-P4	ESP32-S2	ESP32-S3	Linux

ESP HTTP Client Example

See the README.md file in the upper level 'examples' directory for more information about examples.

TLS ciphersuite and group configuration

esp_http_client_config_t has two fields that restrict the TLS handshake of one client:

• ciphersuites_list is a zero-terminated array of IANA ciphersuite identifiers.
• groups_list is a zero-terminated array of IANA supported group identifiers. The groups are the named groups that are used for key exchange.

https_with_restricted_tls_lists() in main/esp_http_client_example.c shows both fields. At startup the example also logs the full lists that the TLS stack supports, through esp_tls_get_ciphersuites_list() and esp_tls_get_supported_groups_list().

Note the rules of the two lists:

• The client does not copy the arrays. Each array must stay valid until esp_http_client_cleanup(). The example uses static arrays.
• A listed ciphersuite works only if its modules are enabled in menuconfig. mbedtls does no dependency check on the list.
• A listed group works only if its curve is enabled in menuconfig.
• The ciphersuites must match the key type of the server certificate. The example list holds an ECDSA suite and an RSA suite for this reason.
• One ciphersuite list covers TLS 1.2 and TLS 1.3. A list that holds only TLS 1.2 suites makes a TLS 1.3 handshake fail. The example list adds a TLS 1.3 suite when CONFIG_MBEDTLS_SSL_PROTO_TLS1_3 is enabled.
• A group list that excludes the group of the server costs one HelloRetryRequest in TLS 1.3. In TLS 1.2 the handshake fails.

For a server, use the ciphersuites_list and groups_list fields of httpd_ssl_config_t.