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#include "lnurl_pay.h"
#include "esp_log.h"
#include "esp_http_client.h"
#include "esp_crt_bundle.h"
#include "cJSON.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
static const char *TAG = "lnurl_pay";
static esp_err_t http_get_json(const char *url, char *resp_buf, size_t resp_buf_size, int *status_out)
{
esp_http_client_config_t config = {
.url = url,
.method = HTTP_METHOD_GET,
.timeout_ms = 15000,
.crt_bundle_attach = esp_crt_bundle_attach,
};
esp_http_client_handle_t client = esp_http_client_init(&config);
if (!client) return ESP_FAIL;
esp_err_t err = esp_http_client_open(client, 0);
if (err != ESP_OK) {
esp_http_client_cleanup(client);
return ESP_FAIL;
}
int content_length = esp_http_client_fetch_headers(client);
(void)content_length;
int status = esp_http_client_get_status_code(client);
if (status_out) *status_out = status;
int resp_len = esp_http_client_read(client, resp_buf, resp_buf_size - 1);
esp_http_client_cleanup(client);
if (resp_len < 0) return ESP_FAIL;
resp_buf[resp_len] = '\0';
return ESP_OK;
}
esp_err_t lnurl_get_invoice(const char *lightning_address, uint64_t amount_sats,
char *bolt11_out, size_t bolt11_out_size)
{
if (!lightning_address || !bolt11_out) return ESP_FAIL;
const char *at = strchr(lightning_address, '@');
if (!at) {
ESP_LOGE(TAG, "Invalid lightning address: missing '@'");
return ESP_FAIL;
}
size_t user_len = at - lightning_address;
char username[64];
if (user_len >= sizeof(username)) return ESP_FAIL;
memcpy(username, lightning_address, user_len);
username[user_len] = '\0';
const char *domain = at + 1;
char url[512];
snprintf(url, sizeof(url), "https://%s/.well-known/lnurlp/%s", domain, username);
ESP_LOGI(TAG, "LNURL-pay step 1: GET %s", url);
char *resp_buf = malloc(4096);
if (!resp_buf) return ESP_ERR_NO_MEM;
int status = 0;
esp_err_t err = http_get_json(url, resp_buf, 4096, &status);
if (err != ESP_OK || status != 200) {
ESP_LOGE(TAG, "LNURL-pay step 1 failed: status=%d err=%s", status, esp_err_to_name(err));
free(resp_buf);
return ESP_FAIL;
}
cJSON *root = cJSON_Parse(resp_buf);
if (!root) {
ESP_LOGE(TAG, "LNURL-pay step 1: invalid JSON");
free(resp_buf);
return ESP_FAIL;
}
cJSON *callback = cJSON_GetObjectItemCaseSensitive(root, "callback");
if (!callback || !cJSON_IsString(callback)) {
ESP_LOGE(TAG, "LNURL-pay step 1: missing callback");
cJSON_Delete(root);
free(resp_buf);
return ESP_FAIL;
}
char callback_url[512];
strncpy(callback_url, callback->valuestring, sizeof(callback_url) - 1);
cJSON *min_sendable = cJSON_GetObjectItemCaseSensitive(root, "minSendable");
cJSON *max_sendable = cJSON_GetObjectItemCaseSensitive(root, "maxSendable");
uint64_t amount_msat = amount_sats * 1000;
if (min_sendable && cJSON_IsNumber(min_sendable) && amount_msat < (uint64_t)min_sendable->valuedouble) {
ESP_LOGE(TAG, "Amount %llumsat below min %g", (unsigned long long)amount_msat, min_sendable->valuedouble);
cJSON_Delete(root);
free(resp_buf);
return ESP_FAIL;
}
if (max_sendable && cJSON_IsNumber(max_sendable) && amount_msat > (uint64_t)max_sendable->valuedouble) {
ESP_LOGE(TAG, "Amount %llumsat above max %g", (unsigned long long)amount_msat, max_sendable->valuedouble);
cJSON_Delete(root);
free(resp_buf);
return ESP_FAIL;
}
cJSON_Delete(root);
char callback_with_amount[768];
snprintf(callback_with_amount, sizeof(callback_with_amount), "%s%samount=%llu",
callback_url, strchr(callback_url, '?') ? "&" : "?",
(unsigned long long)amount_msat);
free(resp_buf);
ESP_LOGI(TAG, "LNURL-pay step 2: GET %s", callback_with_amount);
resp_buf = malloc(4096);
if (!resp_buf) return ESP_ERR_NO_MEM;
err = http_get_json(callback_with_amount, resp_buf, 4096, &status);
if (err != ESP_OK || status != 200) {
ESP_LOGE(TAG, "LNURL-pay step 2 failed: status=%d", status);
free(resp_buf);
return ESP_FAIL;
}
root = cJSON_Parse(resp_buf);
free(resp_buf);
if (!root) return ESP_FAIL;
cJSON *pr = cJSON_GetObjectItemCaseSensitive(root, "pr");
if (!pr || !cJSON_IsString(pr)) {
ESP_LOGE(TAG, "LNURL-pay step 2: missing 'pr' (bolt11)");
cJSON_Delete(root);
return ESP_FAIL;
}
size_t pr_len = strlen(pr->valuestring);
if (pr_len >= bolt11_out_size) {
ESP_LOGE(TAG, "BOLT11 too long: %zu >= %zu", pr_len, bolt11_out_size);
cJSON_Delete(root);
return ESP_FAIL;
}
memcpy(bolt11_out, pr->valuestring, pr_len + 1);
cJSON_Delete(root);
ESP_LOGI(TAG, "Got BOLT11 invoice (%zu bytes) for %llu sats", pr_len, (unsigned long long)amount_sats);
return ESP_OK;
}
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