session server REFACTOR move nc_base64der_to_cert

Moved this function from session_server_tls file, because it shall be
used by more different files in the future.

Author: roman

src/session.c

@@ -138,6 +138,24 @@ nc_poll(struct pollfd *pfd, uint16_t pfd_count, int timeout_ms)
 
 #ifdef NC_ENABLED_SSH_TLS
 
+void *
+nc_base64der_to_cert(const char *data)
+{
+    char *buf = NULL;
+    void *cert;
+
+    NC_CHECK_ARG_RET(NULL, data, NULL);
+
+    if (asprintf(&buf, "%s%s%s", "-----BEGIN CERTIFICATE-----\n", data, "\n-----END CERTIFICATE-----") == -1) {
+        ERRMEM;
+        return NULL;
+    }
+
+    cert = nc_tls_pem_to_cert_wrap(buf);
+    free(buf);
+    return cert;
+}
+
 const char *
 nc_privkey_format_to_str(NC_PRIVKEY_FORMAT format)
 {

src/session_p.h

@@ -756,6 +756,14 @@ const char *nc_privkey_format_to_str(NC_PRIVKEY_FORMAT format);
  */
 int nc_is_pk_subject_public_key_info(const char *b64);
 
+/**
+ * @brief Import a Base64 DER encoded certificate data.
+ *
+ * @param[in] data Base64 DER encoded certificate data.
+ * @return Imported certificate on success, NULL on error.
+ */
+void * nc_base64der_to_cert(const char *data);
+
 #endif /* NC_ENABLED_SSH_TLS */
 
 void *nc_realloc(void *ptr, size_t size);

src/session_server_tls.c

@@ -99,24 +99,6 @@ nc_server_tls_ts_ref_get_certs(const char *referenced_name, struct nc_certificat
     return 0;
 }
 
-static void *
-nc_base64der_to_cert(const char *in)
-{
-    char *buf = NULL;
-    void *cert;
-
-    NC_CHECK_ARG_RET(NULL, in, NULL);
-
-    if (asprintf(&buf, "%s%s%s", "-----BEGIN CERTIFICATE-----\n", in, "\n-----END CERTIFICATE-----") == -1) {
-        ERRMEM;
-        return NULL;
-    }
-
-    cert = nc_tls_pem_to_cert_wrap(buf);
-    free(buf);
-    return cert;
-}
-
 static void *
 nc_base64der_to_privkey(const char *in, const char *key_str)
 {