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/* Copyright (C) 2015-2025 maClara, LLC <info@maclara-llc.com>
This file is part of the JWT C Library
SPDX-License-Identifier: MPL-2.0
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <jwt.h>
#include "base64.h"
#include "jwt-private.h"
static int write_js(const json_t *js, char **buf)
{
*buf = json_dumps(js, JSON_SORT_KEYS | JSON_COMPACT);
return *buf == NULL ? 1 : 0;
}
int jwt_head_setup(jwt_t *jwt)
{
jwt_value_t jval;
if (jwt->alg != JWT_ALG_NONE) {
/* Only set default 'typ' header if it has not been defined,
* allowing for any value of it. This allows for signaling
* of application specific extensions to JWT, such as PASSporT,
* RFC 8225. */
jwt_set_SET_STR(&jval, "typ", "JWT");
if (jwt_header_set(jwt, &jval)) {
if (jval.error != JWT_VALUE_ERR_EXIST) {
// LCOV_EXCL_START
jwt_write_error(jwt,
"Error setting \"typ\" in header");
return 1;
// LCOV_EXCL_STOP
}
}
}
jwt_set_SET_STR(&jval, "alg", jwt_alg_str(jwt->alg));
jval.replace = 1;
if (jwt_header_set(jwt, &jval)) {
// LCOV_EXCL_START
jwt_write_error(jwt, "Error setting \"alg\" in header");
return 1;
// LCOV_EXCL_STOP
}
return 0;
}
static int jwt_encode(jwt_t *jwt, char **out)
{
char_auto *head = NULL, *payload = NULL, *sig = NULL;
char *buf = NULL;
int ret, head_len, payload_len;
unsigned int sig_len;
if (out == NULL) {
// LCOV_EXCL_START
jwt_write_error(jwt, "No string passed to write out to");
return 1;
// LCOV_EXCL_STOP
}
*out = NULL;
/* First the header. */
ret = write_js(jwt->headers, &buf);
if (ret)
return 1; // LCOV_EXCL_LINE
/* Encode it */
head_len = jwt_base64uri_encode(&head, buf, (int)strlen(buf));
jwt_freemem(buf);
if (head_len <= 0) {
// LCOV_EXCL_START
jwt_write_error(jwt, "Error encoding header");
return 1;
// LCOV_EXCL_STOP
}
/* Now the payload. */
ret = write_js(jwt->claims, &buf);
if (ret) {
// LCOV_EXCL_START
jwt_write_error(jwt, "Error writing payload");
return 1;
// LCOV_EXCL_STOP
}
payload_len = jwt_base64uri_encode(&payload, buf, (int)strlen(buf));
jwt_freemem(buf);
if (payload_len <= 0) {
// LCOV_EXCL_START
jwt_write_error(jwt, "Error encoding payload");
return 1;
// LCOV_EXCL_STOP
}
/* The part we need to sign, but add space for 2 dots and a nil */
buf = jwt_malloc(head_len + payload_len + 3);
if (buf == NULL) {
// LCOV_EXCL_START
jwt_write_error(jwt, "Error allocating memory");
return 1;
// LCOV_EXCL_STOP
}
strcpy(buf, head);
strcat(buf, ".");
strcat(buf, payload);
if (jwt->alg == JWT_ALG_NONE) {
/* Add the trailing dot, and send it back */
strcat(buf, ".");
*out = buf;
return 0;
}
/* At this point buf has "head.payload" */
/* Now the signature. */
ret = jwt_sign(jwt, &sig, &sig_len, buf, strlen(buf));
jwt_freemem(buf);
if (ret) {
// LCOV_EXCL_START
jwt_write_error(jwt, "Error allocating memory");
return ret;
// LCOV_EXCL_STOP
}
ret = jwt_base64uri_encode(&buf, sig, sig_len);
/* At this point buf has b64 of sig and ret is size of it */
if (ret < 0) {
// LCOV_EXCL_START
jwt_write_error(jwt, "Error allocating memory");
return 1;
// LCOV_EXCL_STOP
}
/* plus 2 dots and a nil */
ret = strlen(head) + strlen(payload) + strlen(buf) + 3;
/* We're good, so let's get it all together */
*out = jwt_malloc(ret);
// LCOV_EXCL_START
if (*out == NULL) {
jwt_write_error(jwt, "Error allocating memory");
ret = 1;
} else {
sprintf(*out, "%s.%s.%s", head, payload, buf);
ret = 0;
}
// LCOV_EXCL_STOP
jwt_freemem(buf);
return ret;
}
char *jwt_encode_str(jwt_t *jwt)
{
char *str = NULL;
if (jwt_encode(jwt, &str))
jwt_freemem(str);
return str;
}
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