Encode header to base64

esp32_device/main/crypto.c

@@ -13,6 +13,7 @@
 #include <mbedtls/sha256.h>
 #include <mbedtls/pk.h>
 #include <mbedtls/x509_csr.h>
+#include <mbedtls/base64.h>
 #include "esp_log.h"
 
 #define ECPARAMS MBEDTLS_ECP_DP_SECP256R1
@@ -189,4 +190,38 @@ char *crypto_get_csr()
     mbedtls_entropy_free(&entropy);
 
     return csr;
+}
+
+char *crypto_encode_base64_safe_url(const char *src, size_t srclen)
+{
+    size_t olen = 0;
+    mbedtls_base64_encode(NULL, 0, &olen, (unsigned char *)src, srclen);
+
+    if (olen < 1)
+    {
+        ESP_LOGE(TAG, "Failed to determine base64 buffer size!");
+        return NULL;
+    }
+
+    char *out = calloc(1, olen);
+    if (!out)
+    {
+        ESP_LOGE(TAG, "Failed to allocate memory for destination buffer!");
+        return NULL;
+    }
+
+    if (mbedtls_base64_encode((unsigned char *)out, olen, &olen, (unsigned char *)src, srclen) != 0)
+    {
+        ESP_LOGE(TAG, "Failed to perfom base64 encoding!");
+        free(out);
+        return NULL;
+    }
+
+    if (out[olen - 1] == '=')
+        out[olen - 1] = '\0';
+
+    if (out[olen - 2] == '=')
+        out[olen - 2] = '\0';
+
+    return out;
 }