Document config restrictions of psk fields
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 5ee9e9d..d0c3677 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -673,10 +673,18 @@
#endif
#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
- unsigned char *psk; /*!< pre-shared key */
- size_t psk_len; /*!< length of the pre-shared key */
- unsigned char *psk_identity; /*!< identity for PSK negotiation */
- size_t psk_identity_len;/*!< length of identity */
+ unsigned char *psk; /*!< pre-shared key. This field should
+ only be set via
+ mbedtls_ssl_conf_psk() */
+ size_t psk_len; /*!< length of the pre-shared key. This
+ field should only be set via
+ mbedtls_ssl_conf_psk() */
+ unsigned char *psk_identity; /*!< identity for PSK negotiation. This
+ field should only be set via
+ mbedtls_ssl_conf_psk() */
+ size_t psk_identity_len;/*!< length of identity. This field should
+ only be set via
+ mbedtls_ssl_conf_psk() */
#endif
#if defined(MBEDTLS_SSL_ALPN)