ip_packet_t parses the header of IP packets

2012-08-08 15:41:03 +02:00
parent ed1f0c234f
commit 2dd47c2442
4 changed files with 286 additions and 0 deletions
@@ -0,0 +1,188 @@
+/*
+ * Copyright (C) 2012 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+
+#include "ip_packet.h"
+
+#include <library.h>
+#include <debug.h>
+
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+
+typedef struct private_ip_packet_t private_ip_packet_t;
+
+/**
+ * Private additions to ip_packet_t.
+ */
+struct private_ip_packet_t {
+
+	/**
+	 * Public members
+	 */
+	ip_packet_t public;
+
+	/**
+	 * Source address
+	 */
+	host_t *src;
+
+	/**
+	 * Destination address
+	 */
+	host_t *dst;
+
+	/**
+	 * IP packet
+	 */
+	chunk_t packet;
+
+	/**
+	 * IP version
+	 */
+	u_int8_t version;
+
+	/**
+	 * Protocol|Next Header field
+	 */
+	u_int8_t next_header;
+
+};
+
+METHOD(ip_packet_t, get_version, u_int8_t,
+	private_ip_packet_t *this)
+{
+	return this->version;
+}
+
+METHOD(ip_packet_t, get_source, host_t*,
+	private_ip_packet_t *this)
+{
+	return this->src;
+}
+
+METHOD(ip_packet_t, get_destination, host_t*,
+	private_ip_packet_t *this)
+{
+	return this->dst;
+}
+
+METHOD(ip_packet_t, get_encoding, chunk_t,
+	private_ip_packet_t *this)
+{
+	return this->packet;
+}
+
+METHOD(ip_packet_t, get_next_header, u_int8_t,
+	private_ip_packet_t *this)
+{
+	return this->next_header;
+}
+
+METHOD(ip_packet_t, clone, ip_packet_t*,
+	private_ip_packet_t *this)
+{
+	return ip_packet_create(this->packet);
+}
+
+METHOD(ip_packet_t, destroy, void,
+	private_ip_packet_t *this)
+{
+	this->src->destroy(this->src);
+	this->dst->destroy(this->dst);
+	chunk_free(&this->packet);
+	free(this);
+}
+
+/**
+ * Described in header.
+ */
+ip_packet_t *ip_packet_create(chunk_t packet)
+{
+	private_ip_packet_t *this;
+	u_int8_t version, next_header;
+	host_t *src, *dst;
+
+	if (packet.len < 1)
+	{
+		DBG1(DBG_ESP, "IP packet too short");
+		goto failed;
+	}
+
+	version = (packet.ptr[0] & 0xf0) >> 4;
+
+	switch (version)
+	{
+		case 4:
+		{
+			struct iphdr *ip;
+
+			if (packet.len < sizeof(struct iphdr))
+			{
+				DBG1(DBG_ESP, "IPv4 packet too short");
+				goto failed;
+			}
+			ip = (struct iphdr*)packet.ptr;
+			src = host_create_from_chunk(AF_INET,
+										 chunk_from_thing(ip->saddr), 0);
+			dst = host_create_from_chunk(AF_INET,
+										 chunk_from_thing(ip->daddr), 0);
+			next_header = ip->protocol;
+			break;
+		}
+		case 6:
+		{
+			struct ip6_hdr *ip;
+
+			if (packet.len < sizeof(struct ip6_hdr))
+			{
+				DBG1(DBG_ESP, "IPv6 packet too short");
+				goto failed;
+			}
+			ip = (struct ip6_hdr*)packet.ptr;
+			src = host_create_from_chunk(AF_INET6,
+										 chunk_from_thing(ip->ip6_src), 0);
+			dst = host_create_from_chunk(AF_INET6,
+										 chunk_from_thing(ip->ip6_dst), 0);
+			next_header = ip->ip6_nxt;
+		}
+		default:
+			DBG1(DBG_ESP, "unsupported IP version");
+			goto failed;
+	}
+
+	INIT(this,
+		.public = {
+			.get_version = _get_version,
+			.get_source = _get_source,
+			.get_destination = _get_destination,
+			.get_next_header = _get_next_header,
+			.get_encoding = _get_encoding,
+			.clone = _clone,
+			.destroy = _destroy,
+		},
+		.src = src,
+		.dst = dst,
+		.packet = packet,
+		.version = version,
+		.next_header = next_header,
+	);
+	return &this->public;
+
+failed:
+	chunk_free(&packet);
+	return NULL;
+}