Added a hook to alter the payload length field of arbitrary payloads

src/conftest/Makefile.am

@@ -6,7 +6,7 @@ conftest_SOURCES = conftest.c conftest.h config.c config.h actions.c actions.h \
 	hooks/hook.h hooks/ike_auth_fill.c hooks/unsort_message.c \
 	hooks/add_notify.c hooks/unencrypted_notify.c hooks/ignore_message.c \
 	hooks/add_payload.c hooks/set_critical.c hooks/force_cookie.c \
-	hooks/set_ike_version.c hooks/pretend_auth.c
+	hooks/set_ike_version.c hooks/pretend_auth.c hooks/set_length.c
 
 INCLUDES = \
 	-I$(top_srcdir)/src/libstrongswan \

src/conftest/hooks/set_length.c

@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2010 Martin Willi
+ * Copyright (C) 2010 revosec AG
+ *
+ * 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 "hook.h"
+
+typedef struct private_set_length_t private_set_length_t;
+
+/**
+ * Private data of an set_length_t object.
+ */
+struct private_set_length_t {
+
+	/**
+	 * Implements the hook_t interface.
+	 */
+	hook_t hook;
+
+	/**
+	 * Alter requests or responses?
+	 */
+	bool req;
+
+	/**
+	 * ID of message to alter.
+	 */
+	int id;
+
+	/**
+	 * Payload type
+	 */
+	char *type;
+
+	/**
+	 * Difference to correct length
+	 */
+	int diff;
+};
+
+METHOD(listener_t, message, bool,
+	private_set_length_t *this, ike_sa_t *ike_sa, message_t *message,
+	bool incoming)
+{
+	if (!incoming &&
+		message->get_request(message) == this->req &&
+		message->get_message_id(message) == this->id)
+	{
+		payload_t *payload;
+		enumerator_t *enumerator;
+		payload_type_t type;
+
+		type = atoi(this->type);
+		if (!type)
+		{
+			type = enum_from_name(payload_type_short_names, this->type);
+			if (type == -1)
+			{
+				DBG1(DBG_CFG, "unknown payload: '%s', skipped", this->type);
+				return TRUE;
+			}
+		}
+		enumerator = message->create_payload_enumerator(message);
+		while (enumerator->enumerate(enumerator, &payload))
+		{
+			if (type == payload->get_type(payload))
+			{
+				encoding_rule_t *rules;
+				size_t count;
+				u_int16_t *len;
+				int i;
+
+				payload->get_encoding_rules(payload, &rules, &count);
+				for (i = 0; i < count; i++)
+				{
+					if (rules[i].type == PAYLOAD_LENGTH)
+					{
+						len = (u_int16_t*)(((void*)payload) + rules[i].offset);
+						DBG1(DBG_CFG, "adjusting length of %N payload "
+							 "from %d to %d", payload_type_short_names, type,
+							 *len, *len + this->diff);
+						*len = *len + this->diff;
+					}
+				}
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+	return TRUE;
+}
+
+METHOD(hook_t, destroy, void,
+	private_set_length_t *this)
+{
+	free(this);
+}
+
+/**
+ * Create the IKE_AUTH fill hook
+ */
+hook_t *set_length_hook_create(char *name)
+{
+	private_set_length_t *this;
+
+	INIT(this,
+		.hook = {
+			.listener = {
+				.message = _message,
+			},
+			.destroy = _destroy,
+		},
+		.req = conftest->test->get_bool(conftest->test,
+										"hooks.%s.request", TRUE, name),
+		.id = conftest->test->get_int(conftest->test,
+										"hooks.%s.id", 0, name),
+		.type = conftest->test->get_str(conftest->test,
+										"hooks.%s.type", "", name),
+		.diff = conftest->test->get_int(conftest->test,
+										"hooks.%s.diff", 0, name),
+	);
+
+	return &this->hook;
+}