rtp_engine: Ignore empty filenames in DTLS configuration.

When applying an empty DTLS configuration the filenames in the
configuration will be empty. This is actually valid to do and
each filename should simply be ignored.

Change-Id: Ib761dc235638a3fb701df337952f831fc3e69539

main/rtp_engine.c

@@ -2118,14 +2118,14 @@ int ast_rtp_dtls_cfg_parse(struct ast_rtp_dtls_cfg *dtls_cfg, const char *name,
 		}
 	} else if (!strcasecmp(name, "dtlscertfile")) {
 		ast_free(dtls_cfg->certfile);
-		if (!ast_file_is_readable(value)) {
+		if (!ast_strlen_zero(value) && !ast_file_is_readable(value)) {
 			ast_log(LOG_ERROR, "%s file %s does not exist or is not readable\n", name, value);
 			return -1;
 		}
 		dtls_cfg->certfile = ast_strdup(value);
 	} else if (!strcasecmp(name, "dtlsprivatekey")) {
 		ast_free(dtls_cfg->pvtfile);
-		if (!ast_file_is_readable(value)) {
+		if (!ast_strlen_zero(value) && !ast_file_is_readable(value)) {
 			ast_log(LOG_ERROR, "%s file %s does not exist or is not readable\n", name, value);
 			return -1;
 		}
@@ -2135,14 +2135,14 @@ int ast_rtp_dtls_cfg_parse(struct ast_rtp_dtls_cfg *dtls_cfg, const char *name,
 		dtls_cfg->cipher = ast_strdup(value);
 	} else if (!strcasecmp(name, "dtlscafile")) {
 		ast_free(dtls_cfg->cafile);
-		if (!ast_file_is_readable(value)) {
+		if (!ast_strlen_zero(value) && !ast_file_is_readable(value)) {
 			ast_log(LOG_ERROR, "%s file %s does not exist or is not readable\n", name, value);
 			return -1;
 		}
 		dtls_cfg->cafile = ast_strdup(value);
 	} else if (!strcasecmp(name, "dtlscapath") || !strcasecmp(name, "dtlscadir")) {
 		ast_free(dtls_cfg->capath);
-		if (!ast_file_is_readable(value)) {
+		if (!ast_strlen_zero(value) && !ast_file_is_readable(value)) {
 			ast_log(LOG_ERROR, "%s file %s does not exist or is not readable\n", name, value);
 			return -1;
 		}