libknot: added error code for unexpected trailing data

src/libknot/errcode.h

@@ -90,6 +90,7 @@ enum knot_error {
 	KNOT_ESYSTEM,
 	KNOT_EFILE,
 	KNOT_ESOAINVAL,
+	KNOT_ETRAIL,
 
 	/* Control states. */
 	KNOT_CTL_ESTOP,

src/libknot/error.c

@@ -90,6 +90,7 @@ static const struct error errors[] = {
 	{ KNOT_ESYSTEM,      "system error" },
 	{ KNOT_EFILE,        "file error" },
 	{ KNOT_ESOAINVAL,    "SOA mismatch" },
+	{ KNOT_ETRAIL,       "trailing data" },
 
 	/* Control states. */
 	{ KNOT_CTL_ESTOP,     "stopping server" },

src/libknot/packet/pkt.c

@@ -771,7 +771,7 @@ int knot_pkt_parse_payload(knot_pkt_t *pkt, unsigned flags)
 
 	/* Check for trailing garbage. */
 	if (pkt->parsed < pkt->size) {
-		return KNOT_EMALF;
+		return KNOT_ETRAIL;
 	}
 
 	return KNOT_EOK;