Line data    Source code

       1            0 : /*
       2              :  * Copyright (c) 2018 Linaro Ltd
       3              :  *
       4              :  * SPDX-License-Identifier: Apache-2.0
       5              :  */
       6              : 
       7              : #ifndef ZEPHYR_INCLUDE_DATA_JWT_H_
       8              : #define ZEPHYR_INCLUDE_DATA_JWT_H_
       9              : 
      10              : #include <zephyr/types.h>
      11              : #include <stdbool.h>
      12              : 
      13              : #ifdef __cplusplus
      14              : extern "C" {
      15              : #endif
      16              : 
      17              : /**
      18              :  * @brief JSON Web Token (JWT) - RFC 7519
      19              :  * @defgroup jwt JSON Web Token (JWT)
      20              :  * @ingroup json
      21              :  * @{
      22              :  */
      23              : 
      24              : /**
      25              :  * @brief JWT data tracking.
      26              :  *
      27              :  * JSON Web Tokens contain several sections, each encoded in Base64URL.
      28              :  * This structure tracks the token as it is being built, including
      29              :  * limits on the amount of available space.  It should be initialized
      30              :  * with jwt_init_builder().
      31              :  */
      32            1 : struct jwt_builder {
      33              :         /** The base of the buffer we are writing to. */
      34            1 :         char *base;
      35              : 
      36              :         /** The place in this buffer where we are currently writing.
      37              :          */
      38            1 :         char *buf;
      39              : 
      40              :         /** The remaining free space in @p buf. */
      41            1 :         size_t len;
      42              : 
      43              :         /**
      44              :          * Flag that is set if we try to write past the end of the
      45              :          * buffer.  If set, the token is not valid.
      46              :          */
      47            1 :         bool overflowed;
      48              : 
      49              :         /* Pending bytes yet to be converted to base64. */
      50            0 :         unsigned char wip[3];
      51              : 
      52              :         /* Number of pending bytes. */
      53            0 :         int pending;
      54              : };
      55              : 
      56              : /**
      57              :  * @brief Initialize the JWT builder.
      58              :  *
      59              :  * Initialize the given JWT builder for the creation of a fresh token.
      60              :  * The buffer size should be long enough to store the entire token.
      61              :  *
      62              :  * @param builder The builder to initialize.
      63              :  * @param buffer The buffer to write the token to.
      64              :  * @param buffer_size The size of this buffer.  The token will be NULL
      65              :  * terminated, which needs to be allowed for in this size.
      66              :  *
      67              :  * @retval 0 Success.
      68              :  * @retval -ENOSPC Buffer is insufficient to initialize.
      69              :  */
      70            1 : int jwt_init_builder(struct jwt_builder *builder,
      71              :                      char *buffer,
      72              :                      size_t buffer_size);
      73              : 
      74              : /**
      75              :  * @brief Add JWT payload.
      76              :  *
      77              :  * Add JWT payload to a previously initialized builder with the following fields:
      78              :  * - Expiration Time
      79              :  * - Issued At
      80              :  * - Audience
      81              :  *
      82              :  * See RFC 7519 section 4.1 to get more information about these fields.
      83              :  *
      84              :  * @param builder A previously initialized builder.
      85              :  * @param exp Expiration Time (epoch format).
      86              :  * @param iat Issued At (epoch format).
      87              :  * @param aud Audience.
      88              :  *
      89              :  * @retval 0 Success.
      90              :  * @retval <0 Failure.
      91              :  */
      92            1 : int jwt_add_payload(struct jwt_builder *builder,
      93              :                     int32_t exp,
      94              :                     int32_t iat,
      95              :                     const char *aud);
      96              : 
      97              : /**
      98              :  * @brief Sign the JWT.
      99              :  *
     100              :  * Sign a previously initialized with payload JWT.
     101              :  *
     102              :  * @param builder A previously initialized builder with payload.
     103              :  * @param der_key Private key to use in DER format.
     104              :  * @param der_key_len Size of the private key in bytes.
     105              :  *
     106              :  * @retval 0 Success.
     107              :  * @retval <0 Failure.
     108              :  */
     109            1 : int jwt_sign(struct jwt_builder *builder,
     110              :              const char *der_key,
     111              :              size_t der_key_len);
     112              : 
     113              : #ifdef __cplusplus
     114              : }
     115              : #endif
     116              : 
     117              : /**
     118              :  * @}
     119              :  */
     120              : 
     121              : #endif /* ZEPHYR_INCLUDE_DATA_JWT_H_ */