[sw_load] It turns out there is a header that needs to be read

The magic " SDP" is occuring twice in the file. The first time
seems to be the file header and the second time it is with the
payload. We will need to parse this somehow...
diff --git a/openbsc/src/abis_nm.c b/openbsc/src/abis_nm.c
index 64b87b5..98683d3 100644
--- a/openbsc/src/abis_nm.c
+++ b/openbsc/src/abis_nm.c
@@ -1341,6 +1341,11 @@
 	return abis_nm_sendmsg(sw->bts, msg);
 }
 
+static int parse_sdp_header(struct abis_nm_sw *sw)
+{
+	return -1;
+}
+
 static int sw_open_file(struct abis_nm_sw *sw, const char *fname)
 {
 	char file_id[12+1];
@@ -1380,8 +1385,11 @@
 		}
 
 		/* TODO: extract that from the filename or content */
-		sw->file_id_len = 0;
-		sw->file_version_len = 0;
+		rc = parse_sdp_header(sw);
+		if (rc < 0) {
+			fprintf(stderr, "Could not parse the ipaccess SDP header\n");
+			return -1;
+		}
 		break;
 	default:
 		/* We don't know how to treat them yet */