WordClockESP/lib/framework/ArduinoJsonJWT.cpp
Rick Watson 62f3d3fc7a fix broken imports under ESP32
use ESP32 rather than ESP_PLATFORM - it's ambigious
standardise to ifdef ESP32 elif defined(ESP8266)
use ifdef over if defined where possible
2019-12-24 11:19:19 +00:00

145 lines
4.1 KiB
C++

#include "ArduinoJsonJWT.h"
ArduinoJsonJWT::ArduinoJsonJWT(String secret) : _secret(secret) {
}
void ArduinoJsonJWT::setSecret(String secret) {
_secret = secret;
}
String ArduinoJsonJWT::getSecret() {
return _secret;
}
/*
* ESP32 uses mbedtls, ESP2866 uses bearssl.
*
* Both come with decent HMAC implmentations supporting sha256, as well as others.
*
* No need to pull in additional crypto libraries - lets use what we already have.
*/
String ArduinoJsonJWT::sign(String& payload) {
unsigned char hmacResult[32];
{
#ifdef ESP32
mbedtls_md_context_t ctx;
mbedtls_md_type_t md_type = MBEDTLS_MD_SHA256;
mbedtls_md_init(&ctx);
mbedtls_md_setup(&ctx, mbedtls_md_info_from_type(md_type), 1);
mbedtls_md_hmac_starts(&ctx, (unsigned char*)_secret.c_str(), _secret.length());
mbedtls_md_hmac_update(&ctx, (unsigned char*)payload.c_str(), payload.length());
mbedtls_md_hmac_finish(&ctx, hmacResult);
mbedtls_md_free(&ctx);
#elif defined(ESP8266)
br_hmac_key_context keyCtx;
br_hmac_key_init(&keyCtx, &br_sha256_vtable, _secret.c_str(), _secret.length());
br_hmac_context hmacCtx;
br_hmac_init(&hmacCtx, &keyCtx, 0);
br_hmac_update(&hmacCtx, payload.c_str(), payload.length());
br_hmac_out(&hmacCtx, hmacResult);
#endif
}
return encode((char*)hmacResult, 32);
}
String ArduinoJsonJWT::buildJWT(JsonObject& payload) {
// serialize, then encode payload
String jwt;
serializeJson(payload, jwt);
jwt = encode(jwt.c_str(), jwt.length());
// add the header to payload
jwt = JWT_HEADER + '.' + jwt;
// add signature
jwt += '.' + sign(jwt);
return jwt;
}
void ArduinoJsonJWT::parseJWT(String jwt, JsonDocument& jsonDocument) {
// clear json document before we begin, jsonDocument wil be null on failure
jsonDocument.clear();
// must have the correct header and delimiter
if (!jwt.startsWith(JWT_HEADER) || jwt.indexOf('.') != JWT_HEADER_SIZE) {
return;
}
// check there is a signature delimieter
int signatureDelimiterIndex = jwt.lastIndexOf('.');
if (signatureDelimiterIndex == JWT_HEADER_SIZE) {
return;
}
// check the signature is valid
String signature = jwt.substring(signatureDelimiterIndex + 1);
jwt = jwt.substring(0, signatureDelimiterIndex);
if (sign(jwt) != signature) {
return;
}
// decode payload
jwt = jwt.substring(JWT_HEADER_SIZE + 1);
jwt = decode(jwt);
// parse payload, clearing json document after failure
DeserializationError error = deserializeJson(jsonDocument, jwt);
if (error != DeserializationError::Ok || !jsonDocument.is<JsonObject>()) {
jsonDocument.clear();
}
}
String ArduinoJsonJWT::encode(const char* cstr, int inputLen) {
// prepare encoder
base64_encodestate _state;
#ifdef ESP32
base64_init_encodestate(&_state);
size_t encodedLength = base64_encode_expected_len(inputLen) + 1;
#elif defined(ESP8266)
base64_init_encodestate_nonewlines(&_state);
size_t encodedLength = base64_encode_expected_len_nonewlines(inputLen) + 1;
#endif
// prepare buffer of correct length, returning an empty string on failure
char* buffer = (char*)malloc(encodedLength * sizeof(char));
if (buffer == nullptr) {
return "";
}
// encode to buffer
int len = base64_encode_block(cstr, inputLen, &buffer[0], &_state);
len += base64_encode_blockend(&buffer[len], &_state);
buffer[len] = 0;
// convert to arduino string, freeing buffer
String value = String(buffer);
free(buffer);
buffer = nullptr;
// remove padding and convert to URL safe form
while (value.length() > 0 && value.charAt(value.length() - 1) == '=') {
value.remove(value.length() - 1);
}
value.replace('+', '-');
value.replace('/', '_');
// return as string
return value;
}
String ArduinoJsonJWT::decode(String value) {
// convert to standard base64
value.replace('-', '+');
value.replace('_', '/');
// prepare buffer of correct length
char buffer[base64_decode_expected_len(value.length()) + 1];
// decode
int len = base64_decode_chars(value.c_str(), value.length(), &buffer[0]);
buffer[len] = 0;
// return as string
return String(buffer);
}