net-test: packetdrill encap support: header metadata definitions

As a first step for packetdrill supporting encapsulated packets,
introduce types to represent all the layers of headers in a packet.


Change-Id: I617a6b977d4fc1f6a51b1b0211dc2c3b39cc2738

gtests/net/packetdrill/header.h

+/*
+ * Copyright 2013 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+/*
+ * Author: ncardwell@google.com (Neal Cardwell)
+ *
+ * Interface and type declarations for packetdrill's representation of
+ * packet headers. We support multi-layer encapsulation. In order to
+ * make it easier to iterate through all the headers in a packet, we
+ * keep separate, explicit metadata about the types and locations of
+ * headers in a packet.
+ */
+
+#ifndef __HEADER_H__
+#define __HEADER_H__
+
+#include "types.h"
+
+#include <assert.h>
+#include <sys/time.h>
+#include "gre.h"
+#include "icmp.h"
+#include "icmpv6.h"
+#include "ip.h"
+#include "ipv6.h"
+#include "tcp.h"
+#include "udp.h"
+
+struct packet;
+
+/* The type of a header in a packet. */
+enum header_t {
+	HEADER_NONE,
+	HEADER_IPV4,
+	HEADER_IPV6,
+	HEADER_GRE,
+	HEADER_TCP,
+	HEADER_UDP,
+	HEADER_ICMPV4,
+	HEADER_ICMPV6,
+	HEADER_NUM_TYPES
+};
+
+/* Metadata about a header in a packet. We support multi-layer encapsulation. */
+struct header {
+	enum header_t type;	/* type of this header */
+	u32 header_bytes;	/* length of this header */
+	u32 total_bytes;	/* length of header plus data inside */
+	union {
+		u8 *ptr;		/* a pointer to the header bits */
+		struct ipv4 *ipv4;
+		struct ipv6 *ipv6;
+		struct gre *gre;
+		struct tcp *tcp;
+		struct udp *udp;
+		struct icmpv4 *icmpv4;
+		struct icmpv6 *icmpv6;
+	} h;
+};
+
+/* Info for a particular type of header. */
+struct header_type_info {
+	const char* name;	/* human-readable protocol name */
+	u8 ip_proto;		/* IP protocol code */
+	u16 eth_proto;		/* Ethernet protocol code */
+
+	/* Call this to finalize the header once we know what's inside... */
+	int (*finish)(struct packet *packet,
+		      struct header *header, struct header *next_inner);
+};
+
+/* Return the info for the given type of header. */
+extern struct header_type_info *header_type_info(enum header_t header_type);
+
+#endif /* __HEADER_H__ */