trafgen: l2: Add ARP header generation logic

Add ARP protocol header fields generation. By default htype ethernet (1)
and ptype IPv4 (0x0800) and the corresponding hlen/plen values will be
initialized and the opcode is set to ARP Request (1).

Source MAC and IP address are set to the device's addresses if not
specified.

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
[tk: rephrase and extend commit message]
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

1 files changed, 50 insertions, 0 deletions

diff --git a/trafgen_l2.c b/trafgen_l2.c
index 1082049..4bbeea1 100644
--- a/trafgen_l2.c
+++ b/trafgen_l2.c
@@ -3,6 +3,9 @@
  * Subject to the GPL, version 2.
  */
 
+#include <net/if_arp.h>
+#include <linux/if_ether.h>
+
 #include "built_in.h"
 #include "trafgen_l2.h"
 #include "trafgen_proto.h"
@@ -26,7 +29,54 @@ static struct proto_hdr eth_hdr = {
 	.header_init	= eth_header_init,
 };
 
+static struct proto_field arp_fields[] = {
+	{ .id = ARP_HTYPE, .len = 2 },
+	{ .id = ARP_PTYPE, .len = 2, .offset = 2 },
+	{ .id = ARP_HLEN,  .len = 1, .offset = 4 },
+	{ .id = ARP_PLEN,  .len = 1, .offset = 5 },
+	{ .id = ARP_OPER,  .len = 2, .offset = 6 },
+	{ .id = ARP_SHA,   .len = 6, .offset = 8 },
+	{ .id = ARP_SPA,   .len = 4, .offset = 14 },
+	{ .id = ARP_THA,   .len = 6, .offset = 18 },
+	{ .id = ARP_TPA,   .len = 4, .offset = 24 },
+};
+
+static void arp_header_init(struct proto_hdr *hdr)
+{
+	struct proto_hdr *lower;
+
+	proto_lower_default_add(PROTO_ETH);
+
+	lower = proto_current_header();
+
+	if (lower->id == PROTO_ETH) {
+		uint8_t bcast[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
+
+		proto_field_set_default_bytes(lower, ETH_DST_ADDR, bcast);
+		proto_field_set_default_be16(lower, ETH_PROTO_ID, ETH_P_ARP);
+	}
+
+	proto_header_fields_add(hdr, arp_fields, array_size(arp_fields));
+
+	/* Generate Announce request by default */
+	proto_field_set_default_be16(hdr, ARP_HTYPE, ARPHRD_ETHER);
+	proto_field_set_default_be16(hdr, ARP_PTYPE, ETH_P_IP);
+	proto_field_set_default_u8(hdr, ARP_HLEN, 6);
+	proto_field_set_default_u8(hdr, ARP_PLEN, 4);
+	proto_field_set_default_be16(hdr, ARP_OPER, ARPOP_REQUEST);
+	proto_field_set_default_dev_mac(hdr, ARP_SHA);
+	proto_field_set_default_dev_ipv4(hdr, ARP_SPA);
+	proto_field_set_default_dev_ipv4(hdr, ARP_TPA);
+}
+
+static struct proto_hdr arp_hdr = {
+	.id		= PROTO_ARP,
+	.layer		= PROTO_L2,
+	.header_init	= arp_header_init,
+};
+
 void protos_l2_init(void)
 {
 	proto_header_register(&eth_hdr);
+	proto_header_register(&arp_hdr);
 }