1 files changed, 82 insertions, 0 deletions
diff --git a/trafgen_l3.c b/trafgen_l3.c
new file mode 100644
index 0000000..dd45395
--- /dev/null
+++ b/trafgen_l3.c
@@ -0,0 +1,82 @@
+/*
+ * netsniff-ng - the packet sniffing beast
+ * Subject to the GPL, version 2.
+ */
+
+#include <linux/if_ether.h>
+
+#include "csum.h"
+#include "built_in.h"
+#include "trafgen_l2.h"
+#include "trafgen_l3.h"
+#include "trafgen_proto.h"
+#include "trafgen_conf.h"
+
+static struct proto_field ipv4_fields[] = {
+	{ .id = IP4_VER,       .len = 1, .offset = 0, .shift = 4, .mask = 0xf0 },
+	{ .id = IP4_IHL,       .len = 1, .offset = 0, .shift = 0, .mask = 0x0f },
+	{ .id = IP4_DSCP,      .len = 1, .offset = 1, .shift = 2, .mask = 0xfc },
+	{ .id = IP4_ECN,       .len = 1, .offset = 1, .shift = 0, .mask = 0x03 },
+	{ .id = IP4_TOS,       .len = 1, .offset = 1 },
+	{ .id = IP4_LEN,       .len = 2, .offset = 2 },
+	{ .id = IP4_ID,        .len = 2, .offset = 4 },
+	{ .id = IP4_FLAGS,     .len = 2, .offset = 6, .shift = 13, .mask = 0xe000 },
+	{ .id = IP4_MF,        .len = 2, .offset = 6, .shift = 13, .mask = 0x2000 },
+	{ .id = IP4_DF,        .len = 2, .offset = 6, .shift = 14, .mask = 0x4000 },
+	{ .id = IP4_FRAG_OFFS, .len = 2, .offset = 6, .shift = 0,  .mask = 0x1fff },
+	{ .id = IP4_TTL,       .len = 1, .offset = 8 },
+	{ .id = IP4_PROTO,     .len = 1, .offset = 9 },
+	{ .id = IP4_CSUM,      .len = 2, .offset = 10 },
+	{ .id = IP4_SADDR,     .len = 4, .offset = 12 },
+	{ .id = IP4_DADDR,     .len = 4, .offset = 16 },
+};
+
+static void ipv4_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)
+		proto_field_set_default_be16(lower, ETH_PROTO_ID, ETH_P_IP);
+	else if (lower->id == PROTO_IP4)
+		proto_field_set_default_u8(lower, IP4_PROTO, IPPROTO_IPIP);
+
+	proto_header_fields_add(hdr, ipv4_fields, array_size(ipv4_fields));
+
+	proto_field_set_default_u8(hdr, IP4_VER, 4);
+	proto_field_set_default_u8(hdr, IP4_IHL, 5);
+	proto_field_set_default_dev_ipv4(hdr, IP4_SADDR);
+}
+
+static void ipv4_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, IP4_LEN, total_len);
+
+	if (!proto_field_is_set(hdr, IP4_CSUM)) {
+		uint16_t csum;
+		uint8_t ihl;
+
+		ihl = proto_field_get_u8(hdr, IP4_IHL);
+		csum = htons(calc_csum(&pkt->payload[hdr->pkt_offset], ihl * 4));
+		proto_field_set_u16(hdr, IP4_CSUM, bswap_16(csum));
+	}
+}
+
+static struct proto_hdr ipv4_hdr = {
+	.id		= PROTO_IP4,
+	.layer		= PROTO_L3,
+	.header_init	= ipv4_header_init,
+	.packet_finish  = ipv4_packet_finish,
+};
+
+void protos_l3_init(void)
+{
+	proto_header_register(&ipv4_hdr);
+}