trafgen: udp: Update csum at runtime if needed

Update UDP csum field at runtime if:

    1) UDP field was changed.

    2) IPv4/6 source/destination addresses were changed (which is a part
       of UDP pseudo header), this is handled by IPv4/6 protocols.

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

2 files changed, 47 insertions, 8 deletions

diff --git a/trafgen_l3.c b/trafgen_l3.c
index 9bb0de9..91052a0 100644
--- a/trafgen_l3.c
+++ b/trafgen_l3.c
@@ -46,6 +46,13 @@ static void ipv4_header_init(struct proto_hdr *hdr)
 static void ipv4_field_changed(struct proto_field *field)
 {
 	field->hdr->is_csum_valid = false;
+
+	if (field->id == IP4_SADDR || field->id == IP4_DADDR) {
+		struct proto_hdr *upper = proto_upper_header(field->hdr);
+
+		if (upper && upper->ops->id == PROTO_UDP)
+			upper->is_csum_valid = false;
+	}
 }
 
 static void ipv4_csum_update(struct proto_hdr *hdr)
@@ -136,6 +143,16 @@ static void ipv6_header_init(struct proto_hdr *hdr)
 	proto_field_set_default_dev_ipv6(hdr, IP6_SADDR);
 }
 
+static void ipv6_field_changed(struct proto_field *field)
+{
+	if (field->id == IP6_SADDR || field->id == IP6_DADDR) {
+		struct proto_hdr *upper = proto_upper_header(field->hdr);
+
+		if (upper && upper->ops->id == PROTO_UDP)
+			upper->is_csum_valid = false;
+	}
+}
+
 #define IPV6_HDR_LEN 40
 
 static void ipv6_packet_finish(struct proto_hdr *hdr)
@@ -171,6 +188,7 @@ static const struct proto_ops ipv6_proto_ops = {
 	.id             = PROTO_IP6,
 	.layer          = PROTO_L3,
 	.header_init    = ipv6_header_init,
+	.field_changed  = ipv6_field_changed,
 	.packet_finish  = ipv6_packet_finish,
 	.set_next_proto = ipv6_set_next_proto,
 };
diff --git a/trafgen_l4.c b/trafgen_l4.c
index 7ec017e..ee8deb4 100644
--- a/trafgen_l4.c
+++ b/trafgen_l4.c
@@ -28,22 +28,29 @@ static void udp_header_init(struct proto_hdr *hdr)
 	proto_header_fields_add(hdr, udp_fields, array_size(udp_fields));
 }
 
-static void udp_packet_finish(struct proto_hdr *hdr)
+static void udp_field_changed(struct proto_field *field)
 {
-	struct proto_hdr *lower = proto_lower_header(hdr);
-	struct packet *pkt = current_packet();
+	field->hdr->is_csum_valid = false;
+}
+
+static void udp_csum_update(struct proto_hdr *hdr)
+{
+	struct proto_hdr *lower;
 	uint16_t total_len;
 	uint16_t csum;
 
-	total_len = pkt->len - hdr->pkt_offset;
-	proto_field_set_default_be16(hdr, UDP_LEN, total_len);
-
+	if (hdr->is_csum_valid)
+		return;
 	if (proto_field_is_set(hdr, UDP_CSUM))
 		return;
-
+	lower = proto_lower_header(hdr);
 	if (!lower)
 		return;
 
+	total_len = packet_get(hdr->pkt_id)->len - hdr->pkt_offset;
+
+	proto_field_set_default_be16(hdr, UDP_CSUM, 0);
+
 	switch (lower->ops->id) {
 	case PROTO_IP4:
 		csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
@@ -58,14 +65,28 @@ static void udp_packet_finish(struct proto_hdr *hdr)
 		break;
 	}
 
-	proto_field_set_be16(hdr, UDP_CSUM, bswap_16(csum));
+	proto_field_set_default_be16(hdr, UDP_CSUM, bswap_16(csum));
+	hdr->is_csum_valid = true;
+}
+
+static void udp_packet_finish(struct proto_hdr *hdr)
+{
+	struct packet *pkt = current_packet();
+	uint16_t total_len;
+
+	total_len = pkt->len - hdr->pkt_offset;
+	proto_field_set_default_be16(hdr, UDP_LEN, total_len);
+
+	udp_csum_update(hdr);
 }
 
 static const struct proto_ops udp_proto_ops = {
 	.id		= PROTO_UDP,
 	.layer		= PROTO_L4,
 	.header_init	= udp_header_init,
+	.packet_update  = udp_csum_update,
 	.packet_finish  = udp_packet_finish,
+	.field_changed  = udp_field_changed,
 };
 
 static struct proto_field tcp_fields[] = {