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jwt_checker_grp(3) Library Functions Manual jwt_checker_grp(3)

NAME

jwt_checker_grp - Checker

SYNOPSIS

Typedefs


typedef struct jwt_checker jwt_checker_t
Opaque Checker object.

Functions


jwt_checker_t * jwt_checker_new (void)
Function to create a new checker instance. void jwt_checker_free (jwt_checker_t *checker)
Frees a previously created checker object. int jwt_checker_error (const jwt_checker_t *checker)
Checks error state of checker object. const char * jwt_checker_error_msg (const jwt_checker_t *checker)
Get the error message contained in a checker object. void jwt_checker_error_clear (jwt_checker_t *checker)
Clear error state in a checker object. int jwt_checker_setkey (jwt_checker_t *checker, const jwt_alg_t alg, const jwk_item_t *key)
Sets a key and algorithm for a checker. int jwt_checker_setcb (jwt_checker_t *checker, jwt_callback_t cb, void *ctx)
Set a callback for generating tokens. void * jwt_checker_getctx (jwt_checker_t *checker)
Retrieve the callback context that was previously set. int jwt_checker_verify (jwt_checker_t *checker, const char *token)
Verify a token.

Detailed Description

Validating a JWT involves decoding the Base64url parts of the JWT then verifying claims and the signature hash. The checker object allows you to configure how you want to perform these steps so you can easily process tokens with one simple call.

Typedef Documentation

typedef struct jwt_checker jwt_checker_t

Opaque Checker object.

Function Documentation

int jwt_checker_error (const jwt_checker_t * checker)

Checks error state of checker object.

Parameters

checker Pointer to a checker object

Returns

0 if no errors exist, non-zero otherwise

void jwt_checker_error_clear (jwt_checker_t * checker)

Clear error state in a checker object.

Parameters

checker Pointer to a checker object

const char * jwt_checker_error_msg (const jwt_checker_t * checker)

Get the error message contained in a checker object.

Parameters

checker Pointer to a checker object

Returns

Pointer to a string with the error message. Can be an empty string if there is no error. Never returns NULL.

void jwt_checker_free (jwt_checker_t * checker)

Frees a previously created checker object.

Parameters

checker Pointer to a checker object

void * jwt_checker_getctx (jwt_checker_t * checker)

Retrieve the callback context that was previously set. This is useful for accessing the context that was previously passed in the setcb function.

Parameters

checker Pointer to a checker object

Returns

Pointer to the context or NULL

jwt_checker_t * jwt_checker_new (void)

Function to create a new checker instance.

Returns

Pointer to a checker object on success, NULL on failure

int jwt_checker_setcb (jwt_checker_t * checker, jwt_callback_t cb, void * ctx)

Set a callback for generating tokens. When verifying a token, this callback will be run after jwt_t has been parsed, but before the token is verified (including signature verification). During this, the callback should only inspect the header or claims in the JWT. Any attempts to make changes to the jwt_t object will not change the rest of the process.

The callback can also set the key and algorithm used to verify the signature. If the callback returns non-zero, then processing will stop and return an error.

The ctx value is also passed to the callback as part of the jwt_value_t struct.

Note

Calling this with a NULL cb param and a new ctx param after already setting the callback will allow updating the ctx passed to the callback. Calling with both values as NULL will disable the callback completely.

Parameters

checker Pointer to a checker object
cb Pointer to a callback function
ctx Pointer to data to pass to the callback function

Returns

0 on success, non-zero otherwise with error set in the checker

int jwt_checker_setkey (jwt_checker_t * checker, const jwt_alg_t alg, const jwk_item_t * key)

Sets a key and algorithm for a checker. See jwt_builder_setkey for detailed information.

Parameters

checker Pointer to a checker object
alg A valid jwt_alg_t type
key A JWK key object

Returns

0 on success, non-zero otherwise with error set in the checker

int jwt_checker_verify (jwt_checker_t * checker, const char * token)

Verify a token.

Note

If you set a callback for this checker, this is when it will be called.

Parameters

checker Pointer to a checker object
token A string containing a token to be verified

Returns

0 on success, non-zero otherwise with error set in the checker

Author

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Version 3.2.2 LibJWT