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esp_tls.h
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esp_tls.h
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// Copyright 2017-2018 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef _ESP_TLS_H_
#define _ESP_TLS_H_
#include <stdbool.h>
#include <sys/socket.h>
#include <fcntl.h>
#include "mbedtls/platform.h"
#include "mbedtls/net_sockets.h"
#include "mbedtls/esp_debug.h"
#include "mbedtls/ssl.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/error.h"
#include "mbedtls/certs.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief ESP-TLS Connection State
*/
typedef enum esp_tls_conn_state {
ESP_TLS_INIT = 0,
ESP_TLS_CONNECTING,
ESP_TLS_HANDSHAKE,
ESP_TLS_FAIL,
ESP_TLS_DONE,
} esp_tls_conn_state_t;
/**
* @brief ESP-TLS configuration parameters
*/
typedef struct esp_tls_cfg {
const char **alpn_protos; /*!< Application protocols required for HTTP2.
If HTTP2/ALPN support is required, a list
of protocols that should be negotiated.
The format is length followed by protocol
name.
For the most common cases the following is ok:
"\x02h2"
- where the first '2' is the length of the protocol and
- the subsequent 'h2' is the protocol name */
const unsigned char *cacert_pem_buf; /*!< Certificate Authority's certificate in a buffer */
unsigned int cacert_pem_bytes; /*!< Size of Certificate Authority certificate
pointed to by cacert_pem_buf */
const unsigned char *clientcert_pem_buf;/*!< Client certificate in a buffer */
unsigned int clientcert_pem_bytes; /*!< Size of client certificate pointed to by
clientcert_pem_buf */
const unsigned char *clientkey_pem_buf; /*!< Client key in a buffer */
unsigned int clientkey_pem_bytes; /*!< Size of client key pointed to by
clientkey_pem_buf */
const unsigned char *clientkey_password;/*!< Client key decryption password string */
unsigned int clientkey_password_len; /*!< String length of the password pointed to by
clientkey_password */
bool non_block; /*!< Configure non-blocking mode. If set to true the
underneath socket will be configured in non
blocking mode after tls session is established */
int timeout_ms; /*!< Network timeout in milliseconds */
bool use_global_ca_store; /*!< Use a global ca_store for all the connections in which
this bool is set. */
} esp_tls_cfg_t;
/**
* @brief ESP-TLS Connection Handle
*/
typedef struct esp_tls {
mbedtls_ssl_context ssl; /*!< TLS/SSL context */
mbedtls_entropy_context entropy; /*!< mbedTLS entropy context structure */
mbedtls_ctr_drbg_context ctr_drbg; /*!< mbedTLS ctr drbg context structure.
CTR_DRBG is deterministic random
bit generation based on AES-256 */
mbedtls_ssl_config conf; /*!< TLS/SSL configuration to be shared
between mbedtls_ssl_context
structures */
mbedtls_net_context server_fd; /*!< mbedTLS wrapper type for sockets */
mbedtls_x509_crt cacert; /*!< Container for the X.509 CA certificate */
mbedtls_x509_crt *cacert_ptr; /*!< Pointer to the cacert being used. */
mbedtls_x509_crt clientcert; /*!< Container for the X.509 client certificate */
mbedtls_pk_context clientkey; /*!< Container for the private key of the client
certificate */
int sockfd; /*!< Underlying socket file descriptor. */
ssize_t (*read)(struct esp_tls *tls, char *data, size_t datalen); /*!< Callback function for reading data from TLS/SSL
connection. */
ssize_t (*write)(struct esp_tls *tls, const char *data, size_t datalen); /*!< Callback function for writing data to TLS/SSL
connection. */
esp_tls_conn_state_t conn_state; /*!< ESP-TLS Connection state */
fd_set rset; /*!< read file descriptors */
fd_set wset; /*!< write file descriptors */
} esp_tls_t;
/**
* @brief Create a new blocking TLS/SSL connection
*
* This function establishes a TLS/SSL connection with the specified host in blocking manner.
*
* @param[in] hostname Hostname of the host.
* @param[in] hostlen Length of hostname.
* @param[in] port Port number of the host.
* @param[in] cfg TLS configuration as esp_tls_cfg_t. If you wish to open
* non-TLS connection, keep this NULL. For TLS connection,
* a pass pointer to esp_tls_cfg_t. At a minimum, this
* structure should be zero-initialized.
* @return pointer to esp_tls_t, or NULL if connection couldn't be opened.
*/
esp_tls_t *esp_tls_conn_new(const char *hostname, int hostlen, int port, const esp_tls_cfg_t *cfg);
/**
* @brief Create a new blocking TLS/SSL connection with a given "HTTP" url
*
* The behaviour is same as esp_tls_conn_new() API. However this API accepts host's url.
*
* @param[in] url url of host.
* @param[in] cfg TLS configuration as esp_tls_cfg_t. If you wish to open
* non-TLS connection, keep this NULL. For TLS connection,
* a pass pointer to 'esp_tls_cfg_t'. At a minimum, this
* structure should be zero-initialized.
* @return pointer to esp_tls_t, or NULL if connection couldn't be opened.
*/
esp_tls_t *esp_tls_conn_http_new(const char *url, const esp_tls_cfg_t *cfg);
/**
* @brief Create a new non-blocking TLS/SSL connection
*
* This function initiates a non-blocking TLS/SSL connection with the specified host, but due to
* its non-blocking nature, it doesn't wait for the connection to get established.
*
* @param[in] hostname Hostname of the host.
* @param[in] hostlen Length of hostname.
* @param[in] port Port number of the host.
* @param[in] cfg TLS configuration as esp_tls_cfg_t. `non_block` member of
* this structure should be set to be true.
* @param[in] tls pointer to esp-tls as esp-tls handle.
*
* @return
* - -1 If connection establishment fails.
* - 0 If connection establishment is in progress.
* - 1 If connection establishment is successful.
*/
int esp_tls_conn_new_async(const char *hostname, int hostlen, int port, const esp_tls_cfg_t *cfg, esp_tls_t *tls);
/**
* @brief Create a new non-blocking TLS/SSL connection with a given "HTTP" url
*
* The behaviour is same as esp_tls_conn_new() API. However this API accepts host's url.
*
* @param[in] url url of host.
* @param[in] cfg TLS configuration as esp_tls_cfg_t.
* @param[in] tls pointer to esp-tls as esp-tls handle.
*
* @return
* - -1 If connection establishment fails.
* - 0 If connection establishment is in progress.
* - 1 If connection establishment is successful.
*/
int esp_tls_conn_http_new_async(const char *url, const esp_tls_cfg_t *cfg, esp_tls_t *tls);
/**
* @brief Write from buffer 'data' into specified tls connection.
*
* @param[in] tls pointer to esp-tls as esp-tls handle.
* @param[in] data Buffer from which data will be written.
* @param[in] datalen Length of data buffer.
*
* @return
* - >0 if write operation was successful, the return value is the number
* of bytes actually written to the TLS/SSL connection.
* - 0 if write operation was not successful. The underlying
* connection was closed.
* - <0 if write operation was not successful, because either an
* error occured or an action must be taken by the calling process.
*/
static inline ssize_t esp_tls_conn_write(esp_tls_t *tls, const void *data, size_t datalen)
{
return tls->write(tls, (char *)data, datalen);
}
/**
* @brief Read from specified tls connection into the buffer 'data'.
*
* @param[in] tls pointer to esp-tls as esp-tls handle.
* @param[in] data Buffer to hold read data.
* @param[in] datalen Length of data buffer.
*
* @return
* - >0 if read operation was successful, the return value is the number
* of bytes actually read from the TLS/SSL connection.
* - 0 if read operation was not successful. The underlying
* connection was closed.
* - <0 if read operation was not successful, because either an
* error occured or an action must be taken by the calling process.
*/
static inline ssize_t esp_tls_conn_read(esp_tls_t *tls, void *data, size_t datalen)
{
return tls->read(tls, (char *)data, datalen);
}
/**
* @brief Close the TLS/SSL connection and free any allocated resources.
*
* This function should be called to close each tls connection opened with esp_tls_conn_new() or
* esp_tls_conn_http_new() APIs.
*
* @param[in] tls pointer to esp-tls as esp-tls handle.
*/
void esp_tls_conn_delete(esp_tls_t *tls);
/**
* @brief Return the number of application data bytes remaining to be
* read from the current record
*
* This API is a wrapper over mbedtls's mbedtls_ssl_get_bytes_avail() API.
*
* @param[in] tls pointer to esp-tls as esp-tls handle.
*
* @return
* - -1 in case of invalid arg
* - bytes available in the application data
* record read buffer
*/
size_t esp_tls_get_bytes_avail(esp_tls_t *tls);
/**
* @brief Create a global CA store with the buffer provided in cfg.
*
* This function should be called if the application wants to use the same CA store for
* multiple connections. The application must call this function before calling esp_tls_conn_new().
*
* @param[in] cacert_pem_buf Buffer which has certificates in pem format. This buffer
* is used for creating a global CA store, which can be used
* by other tls connections.
* @param[in] cacert_pem_bytes Length of the buffer.
*
* @return
* - ESP_OK if creating global CA store was successful.
* - Other if an error occured or an action must be taken by the calling process.
*/
esp_err_t esp_tls_set_global_ca_store(const unsigned char *cacert_pem_buf, const unsigned int cacert_pem_bytes);
/**
* @brief Get the pointer to the global CA store currently being used.
*
* The application must first call esp_tls_set_global_ca_store(). Then the same
* CA store could be used by the application for APIs other than esp_tls.
*
* @note Modifying the pointer might cause a failure in verifying the certificates.
*
* @return
* - Pointer to the global CA store currently being used if successful.
* - NULL if there is no global CA store set.
*/
mbedtls_x509_crt *esp_tls_get_global_ca_store();
/**
* @brief Free the global CA store currently being used.
*
* The memory being used by the global CA store to store all the parsed certificates is
* freed up. The application can call this API if it no longer needs the global CA store.
*/
void esp_tls_free_global_ca_store();
#ifdef __cplusplus
}
#endif
#endif /* ! _ESP_TLS_H_ */