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#include "relay_validator.h"
#include "relay_types.h"
#include "esp_log.h"
#include "mbedtls/sha256.h"
#include "secp256k1.h"
#include "secp256k1_extrakeys.h"
#include "secp256k1_schnorrsig.h"
#include "cJSON.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include <stddef.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
static const char *TAG = "relay_validator";
static int hex_to_bytes(const char *hex, size_t hex_len, uint8_t *out, size_t out_len)
{
if (hex_len != out_len * 2) return -1;
for (size_t i = 0; i < out_len; i++) {
unsigned int byte;
if (sscanf(hex + i * 2, "%02x", &byte) != 1) return -1;
out[i] = (uint8_t)byte;
}
return 0;
}
static char *serialize_event_for_id(const char *event_json, size_t event_len)
{
cJSON *obj = cJSON_ParseWithLength(event_json, event_len);
if (!obj) return NULL;
cJSON *serial = cJSON_CreateArray();
cJSON_AddItemToArray(serial, cJSON_CreateNumber(0));
cJSON_AddItemToArray(serial, cJSON_CreateString(
cJSON_GetObjectItem(obj, "pubkey")->valuestring));
cJSON_AddItemToArray(serial, cJSON_CreateNumber(
cJSON_GetObjectItem(obj, "created_at")->valuedouble));
cJSON_AddItemToArray(serial, cJSON_CreateNumber(
cJSON_GetObjectItem(obj, "kind")->valueint));
cJSON *tags = cJSON_GetObjectItem(obj, "tags");
cJSON_AddItemToArray(serial, cJSON_Duplicate(tags, 1));
cJSON_AddItemToArray(serial, cJSON_CreateString(
cJSON_GetObjectItem(obj, "content")->valuestring));
char *result = cJSON_PrintUnformatted(serial);
cJSON_Delete(serial);
cJSON_Delete(obj);
return result;
}
static bool verify_event_id(const char *event_json, size_t event_len,
const uint8_t expected_id[32])
{
char *serialized = serialize_event_for_id(event_json, event_len);
if (!serialized) return false;
uint8_t hash[32];
mbedtls_sha256((const unsigned char *)serialized, strlen(serialized), hash, 0);
free(serialized);
return memcmp(hash, expected_id, 32) == 0;
}
static bool verify_schnorr_sig(const uint8_t pubkey[32], const uint8_t msg[32],
const uint8_t sig[64])
{
secp256k1_context *ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY);
if (!ctx) return false;
secp256k1_xonly_pubkey xonly_pub;
if (!secp256k1_xonly_pubkey_parse(ctx, &xonly_pub, pubkey)) {
secp256k1_context_destroy(ctx);
return false;
}
bool valid = secp256k1_schnorrsig_verify(ctx, sig, msg, 32, &xonly_pub);
secp256k1_context_destroy(ctx);
return valid;
}
bool relay_validator_verify_event(const char *event_json, size_t event_len)
{
cJSON *obj = cJSON_ParseWithLength(event_json, event_len);
if (!obj) {
ESP_LOGD(TAG, "Invalid JSON");
return false;
}
cJSON *id_item = cJSON_GetObjectItem(obj, "id");
cJSON *pk_item = cJSON_GetObjectItem(obj, "pubkey");
cJSON *sig_item = cJSON_GetObjectItem(obj, "sig");
if (!id_item || !pk_item || !sig_item) {
cJSON_Delete(obj);
ESP_LOGD(TAG, "Missing required fields");
return false;
}
const char *id_hex = id_item->valuestring;
const char *pk_hex = pk_item->valuestring;
const char *sig_hex = sig_item->valuestring;
if (strlen(id_hex) != 64 || strlen(pk_hex) != 64 || strlen(sig_hex) != 128) {
cJSON_Delete(obj);
ESP_LOGD(TAG, "Invalid field lengths");
return false;
}
uint8_t event_id[32], pubkey[32], sig[64];
if (hex_to_bytes(id_hex, 64, event_id, 32) != 0 ||
hex_to_bytes(pk_hex, 64, pubkey, 32) != 0 ||
hex_to_bytes(sig_hex, 128, sig, 64) != 0) {
cJSON_Delete(obj);
ESP_LOGD(TAG, "Invalid hex encoding");
return false;
}
cJSON_Delete(obj);
if (!verify_event_id(event_json, event_len, event_id)) {
ESP_LOGD(TAG, "Event ID mismatch");
return false;
}
if (!verify_schnorr_sig(pubkey, event_id, sig)) {
ESP_LOGD(TAG, "Invalid signature");
return false;
}
return true;
}
validation_result_t relay_validator_check(const uint8_t *id,
const uint8_t *pubkey,
uint64_t created_at,
int kind,
const char *content,
size_t content_len,
const char *tags_json,
const uint8_t *sig,
const validator_config_t *config)
{
(void)content; (void)content_len; (void)tags_json;
if (config) {
if (config->max_future_sec > 0) {
int64_t now = (int64_t)(xTaskGetTickCount() / configTICK_RATE_HZ);
if ((int64_t)created_at > now + config->max_future_sec)
return VALIDATION_ERR_FUTURE;
}
}
if (!verify_schnorr_sig(pubkey, id, sig))
return VALIDATION_ERR_SIG;
return VALIDATION_OK;
}
const char *relay_validator_result_string(validation_result_t result)
{
switch (result) {
case VALIDATION_OK: return "ok";
case VALIDATION_ERR_SCHEMA: return "invalid: schema";
case VALIDATION_ERR_ID: return "invalid: event id";
case VALIDATION_ERR_SIG: return "invalid: signature";
case VALIDATION_ERR_EXPIRED: return "invalid: expired";
case VALIDATION_ERR_FUTURE: return "invalid: future";
case VALIDATION_ERR_DUPLICATE: return "duplicate";
case VALIDATION_ERR_POW: return "pow: insufficient";
case VALIDATION_ERR_BLOCKED: return "blocked";
case VALIDATION_ERR_TOO_OLD: return "invalid: too old";
default: return "error: unknown";
}
}
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