[transport] detect and warn about unaligned esc sequences

volkszaehler · Jan 5, 2023 · 50834d7 · 50834d7
1 parent 559ca1e
commit 50834d7
Showing 1 changed file with 12 additions and 0 deletions.
diff --git a/sml/src/sml_transport.c b/sml/src/sml_transport.c
@@ -90,6 +90,17 @@ size_t sml_transport_read(int fd, unsigned char *buffer, size_t max_len) {
 			return 0;
 		}
 
+		for (int i=1;i<4;i++){
+			if (len>i && memcmp(&buf[len-i], esc_seq, 4) == 0){
+				if (buf[len-i+4] == 0x1a) {
+					fprintf(stderr, "libsml: warning: unaligned end esc sequence found in data, stream desynced?\n");
+				} else if (buf[len-i+4] == 0x01) {
+					fprintf(stderr, "libsml: warning: unaligned (likely) start esc sequence found in data, stream desynced?\n");
+				} else {
+					fprintf(stderr, "libsml: warning: unaligned esc sequence found in data, stream desynced?\n");
+				}
+			}
+		}
 		if (memcmp(&buf[len], esc_seq, 4) == 0) {
 			// found esc sequence
 			len += 4;
@@ -105,6 +116,7 @@ size_t sml_transport_read(int fd, unsigned char *buffer, size_t max_len) {
 			} else {
 				// don't read other escaped sequences yet
 				fprintf(stderr, "libsml: error: unrecognized sequence\n");
+				fprintf(stderr, "libsml: %xi at %i\n",buf[len],len);
 				return 0;
 			}
 		}