pkt: packet copy basic implementation

src/libknot/packet/pkt.c

@@ -202,6 +202,37 @@ knot_pkt_t *knot_pkt_new(void *wire, uint16_t len, mm_ctx_t *mm)
 	return pkt_new_mm(wire, len, mm);
 }
 
+knot_pkt_t *knot_pkt_copy(const knot_pkt_t *pkt, mm_ctx_t *mm)
+{
+	dbg_packet("%s(%p, %p)\n", __func__, pkt, mm);
+	if (pkt == NULL) {
+		return NULL;
+	}
+
+	knot_pkt_t *copy = knot_pkt_new(NULL, pkt->max_size, mm);
+	if (copy == NULL) {
+		return NULL;
+	}
+
+	copy->size = pkt->size;
+	memcpy(copy->wire, pkt->wire, copy->size);
+
+	/* Copy TSIG RR back to wire. */
+	if (pkt->tsig_rr) {
+		int ret = knot_tsig_append(copy->wire, &copy->size, copy->max_size,
+		                           pkt->tsig_rr);
+		if (ret != KNOT_EOK) {
+			knot_pkt_free(&copy);
+			return NULL;
+		}
+	}
+
+	/* @note This could be done more effectively if needed. */
+	knot_pkt_parse(copy, 0);
+
+	return copy;
+}
+
 int knot_pkt_init_response(knot_pkt_t *pkt, const knot_pkt_t *query)
 {
 	dbg_packet("%s(%p, %p)\n", __func__, pkt, query);

src/libknot/packet/pkt.h

@@ -130,6 +130,18 @@ typedef struct knot_pkt {
  */
 knot_pkt_t *knot_pkt_new(void *wire, uint16_t len, mm_ctx_t *mm);
 
+/*!
+ * \brief Copy packet.
+ *
+ * \note Current implementation is not very efficient, as it re-parses the wire.
+ *
+ * \param pkt Source packet.
+ * \param mm Memory context.
+ *
+ * \return new packet or NULL
+ */
+knot_pkt_t *knot_pkt_copy(const knot_pkt_t *pkt, mm_ctx_t *mm);
+
 /*!
  * \brief Initialized response from query packet.
  *

tests/pkt.c

@@ -41,9 +41,32 @@ const char *g_rdata[DATACOUNT] = {
 #define RDVAL(i) ((const uint8_t*)(g_rdata[(i)] + 1))
 #define RDLEN(i) ((uint16_t)(g_rdata[(i)][0]))
 
+/* @note Packet equivalence test, 5 checks. */
+static void packet_match(knot_pkt_t *in, knot_pkt_t *out)
+{
+	/* Check counts */
+	is_int(knot_wire_get_qdcount(out->wire),
+	       knot_wire_get_qdcount(in->wire), "pkt: QD match");
+	is_int(knot_wire_get_ancount(out->wire),
+	       knot_wire_get_ancount(in->wire), "pkt: AN match");
+	is_int(knot_wire_get_nscount(out->wire),
+	       knot_wire_get_nscount(in->wire), "pkt: NS match");
+	is_int(knot_wire_get_arcount(out->wire),
+	       knot_wire_get_arcount(in->wire), "pkt: AR match");
+
+	/* Check RRs */
+	int rr_matched = 0;
+	for (unsigned i = 0; i < NAMECOUNT; ++i) {
+		if (knot_rrset_equal(&out->rr[i], &in->rr[i], KNOT_RRSET_COMPARE_WHOLE) > 0) {
+			++rr_matched;
+		}
+	}
+	is_int(NAMECOUNT, rr_matched, "pkt: RR content match");
+}
+
 int main(int argc, char *argv[])
 {
-	plan(25);
+	plan(30);
 
 	/* Create memory pool context. */
 	int ret = 0;
@@ -146,34 +169,23 @@ int main(int argc, char *argv[])
 	ret = knot_pkt_parse_payload(in, 0);
 	ok(ret == KNOT_EOK, "pkt: read payload");
 
-	/* Check qname. */
-	ok(knot_dname_is_equal(knot_pkt_qname(out),
-	                       knot_pkt_qname(in)), "pkt: equal qname");
+	/* Compare parsed packet to written packet. */
+	packet_match(in, out);
 
-	/* Check counts */
-	is_int(knot_wire_get_qdcount(out->wire),
-	       knot_wire_get_qdcount(in->wire), "pkt: QD match");
-	is_int(knot_wire_get_ancount(out->wire),
-	       knot_wire_get_ancount(in->wire), "pkt: AN match");
-	is_int(knot_wire_get_nscount(out->wire),
-	       knot_wire_get_nscount(in->wire), "pkt: NS match");
-	is_int(knot_wire_get_arcount(out->wire),
-	       knot_wire_get_arcount(in->wire), "pkt: AR match");
+	/*
+	 * Copied packet tests.
+	 */
+	knot_pkt_t *copy = knot_pkt_copy(in, &in->mm);
+	ok(copy != NULL, "pkt: create packet copy");
 
-	/* Check RRs */
-	int rr_matched = 0;
-	for (unsigned i = 0; i < NAMECOUNT; ++i) {
-		if (knot_rrset_equal(&out->rr[i], &in->rr[i], KNOT_RRSET_COMPARE_WHOLE) > 0) {
-			++rr_matched;
-		}
-	}
-	is_int(NAMECOUNT, rr_matched, "pkt: RR content match");
+	/* Compare copied packet to original. */
+	packet_match(in, copy);
 
 	/* Free packets. */
+	knot_pkt_free(&copy);
 	knot_pkt_free(&out);
 	knot_pkt_free(&in);
-	ok(in == NULL, "pkt: free");
-	ok(out == NULL, "pkt: free");
+	ok(in == NULL && out == NULL && copy == NULL, "pkt: free");
 
 	/* Free extra data. */
 	for (unsigned i = 0; i < NAMECOUNT; ++i) {