473 lines
12 KiB
C
473 lines
12 KiB
C
/*
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* Copyright (C) 2006-2007 Martin Willi
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* Copyright (C) 2006 Tobias Brunner, Daniel Roethlisberger
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* HSR Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include "ike_natd.h"
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#include <string.h>
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#include <daemon.h>
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#include <config/peer_cfg.h>
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#include <crypto/hashers/hasher.h>
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#include <encoding/payloads/notify_payload.h>
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typedef struct private_ike_natd_t private_ike_natd_t;
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/**
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* Private members of a ike_natd_t task.
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*/
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struct private_ike_natd_t {
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/**
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* Public methods and task_t interface.
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*/
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ike_natd_t public;
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/**
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* Assigned IKE_SA.
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*/
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ike_sa_t *ike_sa;
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/**
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* Are we the initiator?
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*/
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bool initiator;
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/**
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* Hasher used to build NAT detection hashes
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*/
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hasher_t *hasher;
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/**
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* Did we process any NAT detection notifys for a source address?
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*/
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bool src_seen;
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/**
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* Did we process any NAT detection notifys for a destination address?
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*/
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bool dst_seen;
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/**
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* Have we found a matching source address NAT hash?
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*/
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bool src_matched;
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/**
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* Have we found a matching destination address NAT hash?
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*/
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bool dst_matched;
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/**
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* whether NAT mappings for our NATed address has changed
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*/
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bool mapping_changed;
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};
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/**
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* Check if UDP encapsulation has to be forced either by config or required
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* by the kernel interface
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*/
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static bool force_encap(ike_cfg_t *ike_cfg)
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{
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if (!ike_cfg->force_encap(ike_cfg))
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{
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return charon->kernel->get_features(charon->kernel) &
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KERNEL_REQUIRE_UDP_ENCAPSULATION;
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}
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return TRUE;
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}
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/**
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* Build NAT detection hash for a host
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*/
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static chunk_t generate_natd_hash(private_ike_natd_t *this,
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ike_sa_id_t *ike_sa_id, host_t *host)
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{
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chunk_t natd_chunk, spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk;
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chunk_t natd_hash;
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uint64_t spi_i, spi_r;
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uint16_t port;
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/* prepare all required chunks */
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spi_i = ike_sa_id->get_initiator_spi(ike_sa_id);
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spi_r = ike_sa_id->get_responder_spi(ike_sa_id);
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spi_i_chunk.ptr = (void*)&spi_i;
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spi_i_chunk.len = sizeof(spi_i);
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spi_r_chunk.ptr = (void*)&spi_r;
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spi_r_chunk.len = sizeof(spi_r);
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port = htons(host->get_port(host));
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port_chunk.ptr = (void*)&port;
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port_chunk.len = sizeof(port);
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addr_chunk = host->get_address(host);
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/* natd_hash = SHA1( spi_i | spi_r | address | port ) */
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natd_chunk = chunk_cat("cccc", spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk);
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if (!this->hasher->allocate_hash(this->hasher, natd_chunk, &natd_hash))
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{
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natd_hash = chunk_empty;
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}
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DBG3(DBG_IKE, "natd_chunk %B", &natd_chunk);
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DBG3(DBG_IKE, "natd_hash %B", &natd_hash);
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chunk_free(&natd_chunk);
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return natd_hash;
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}
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/**
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* Build a NAT detection notify payload.
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*/
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static notify_payload_t *build_natd_payload(private_ike_natd_t *this,
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notify_type_t type, host_t *host)
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{
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chunk_t hash;
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notify_payload_t *notify;
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ike_sa_id_t *ike_sa_id;
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ike_cfg_t *config;
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ike_sa_id = this->ike_sa->get_id(this->ike_sa);
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config = this->ike_sa->get_ike_cfg(this->ike_sa);
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if (force_encap(config) && type == NAT_DETECTION_SOURCE_IP)
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{
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uint32_t addr;
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/* chunk_hash() is randomly keyed so this produces a random IPv4 address
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* that changes with every restart but otherwise stays the same */
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addr = chunk_hash(chunk_from_chars(0x00, 0x00, 0x00, 0x00));
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host = host_create_from_chunk(AF_INET, chunk_from_thing(addr), 0);
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hash = generate_natd_hash(this, ike_sa_id, host);
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host->destroy(host);
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}
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else
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{
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hash = generate_natd_hash(this, ike_sa_id, host);
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}
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if (!hash.len)
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{
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return NULL;
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}
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notify = notify_payload_create(PLV2_NOTIFY);
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notify->set_notify_type(notify, type);
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notify->set_notification_data(notify, hash);
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chunk_free(&hash);
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return notify;
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}
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/**
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* read notifys from message and evaluate them
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*/
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static void process_payloads(private_ike_natd_t *this, message_t *message)
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{
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enumerator_t *enumerator;
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payload_t *payload;
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notify_payload_t *notify;
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chunk_t hash, src_hash, dst_hash;
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ike_sa_id_t *ike_sa_id;
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host_t *me, *other;
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ike_cfg_t *config;
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/* Precompute NAT-D hashes for incoming NAT notify comparison */
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ike_sa_id = message->get_ike_sa_id(message);
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me = message->get_destination(message);
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other = message->get_source(message);
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dst_hash = generate_natd_hash(this, ike_sa_id, me);
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src_hash = generate_natd_hash(this, ike_sa_id, other);
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DBG3(DBG_IKE, "precalculated src_hash %B", &src_hash);
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DBG3(DBG_IKE, "precalculated dst_hash %B", &dst_hash);
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enumerator = message->create_payload_enumerator(message);
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while (enumerator->enumerate(enumerator, &payload))
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{
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if (payload->get_type(payload) != PLV2_NOTIFY)
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{
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continue;
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}
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notify = (notify_payload_t*)payload;
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switch (notify->get_notify_type(notify))
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{
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case NAT_DETECTION_DESTINATION_IP:
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{
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this->dst_seen = TRUE;
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hash = notify->get_notification_data(notify);
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if (!this->dst_matched)
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{
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DBG3(DBG_IKE, "received dst_hash %B", &hash);
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if (chunk_equals(hash, dst_hash))
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{
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this->dst_matched = TRUE;
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}
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}
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/* RFC4555 says we should also compare against IKE_SA_INIT
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* NATD payloads, but this does not work: We are running
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* there at port 500, but use 4500 afterwards... */
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if (message->get_exchange_type(message) == INFORMATIONAL &&
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this->initiator && !this->dst_matched)
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{
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this->mapping_changed = this->ike_sa->has_mapping_changed(
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this->ike_sa, hash);
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}
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break;
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}
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case NAT_DETECTION_SOURCE_IP:
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{
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this->src_seen = TRUE;
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if (!this->src_matched)
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{
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hash = notify->get_notification_data(notify);
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DBG3(DBG_IKE, "received src_hash %B", &hash);
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if (chunk_equals(hash, src_hash))
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{
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this->src_matched = TRUE;
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}
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}
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break;
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}
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default:
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break;
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}
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}
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enumerator->destroy(enumerator);
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chunk_free(&src_hash);
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chunk_free(&dst_hash);
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if (this->src_seen && this->dst_seen)
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{
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this->ike_sa->enable_extension(this->ike_sa, EXT_NATT);
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this->ike_sa->set_condition(this->ike_sa, COND_NAT_HERE,
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!this->dst_matched);
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this->ike_sa->set_condition(this->ike_sa, COND_NAT_THERE,
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!this->src_matched);
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config = this->ike_sa->get_ike_cfg(this->ike_sa);
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if (this->dst_matched && this->src_matched &&
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force_encap(config))
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{
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this->ike_sa->set_condition(this->ike_sa, COND_NAT_FAKE, TRUE);
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}
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}
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}
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METHOD(task_t, process_i, status_t,
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private_ike_natd_t *this, message_t *message)
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{
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process_payloads(this, message);
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if (message->get_exchange_type(message) == IKE_SA_INIT)
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{
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peer_cfg_t *peer_cfg = this->ike_sa->get_peer_cfg(this->ike_sa);
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if (this->ike_sa->has_condition(this->ike_sa, COND_NAT_ANY) ||
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/* if peer supports NAT-T, we switch to port 4500 even
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* if no NAT is detected. can't be done later (when we would know
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* whether the peer supports MOBIKE) because there would be no
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* exchange to actually do the switch (other than a forced DPD). */
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(peer_cfg->use_mobike(peer_cfg) &&
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this->ike_sa->supports_extension(this->ike_sa, EXT_NATT)))
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{
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this->ike_sa->float_ports(this->ike_sa);
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}
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}
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return SUCCESS;
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}
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METHOD(task_t, build_i, status_t,
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private_ike_natd_t *this, message_t *message)
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{
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notify_payload_t *notify;
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enumerator_t *enumerator;
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ike_cfg_t *ike_cfg;
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host_t *host;
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if (this->hasher == NULL)
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{
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DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported");
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return NEED_MORE;
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}
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ike_cfg = this->ike_sa->get_ike_cfg(this->ike_sa);
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/* destination is always set */
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host = message->get_destination(message);
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notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, host);
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if (notify)
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{
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message->add_payload(message, (payload_t*)notify);
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}
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/* source may be any, we have 3 possibilities to get our source address:
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* 1. It is defined in the config => use the one of the IKE_SA
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* 2. We do a routing lookup in the kernel interface
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* 3. Include all possible addresses
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*/
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host = message->get_source(message);
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if (!host->is_anyaddr(host) || force_encap(ike_cfg))
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{ /* 1. or if we force UDP encap, as it doesn't matter if it's %any */
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notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
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if (notify)
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{
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message->add_payload(message, (payload_t*)notify);
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}
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}
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else
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{
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host = charon->kernel->get_source_addr(charon->kernel,
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this->ike_sa->get_other_host(this->ike_sa), NULL);
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if (host)
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{ /* 2. */
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host->set_port(host, ike_cfg->get_my_port(ike_cfg));
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notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
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if (notify)
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{
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message->add_payload(message, (payload_t*)notify);
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}
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host->destroy(host);
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}
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else
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{ /* 3. */
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enumerator = charon->kernel->create_address_enumerator(
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charon->kernel, ADDR_TYPE_REGULAR);
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while (enumerator->enumerate(enumerator, (void**)&host))
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{
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/* apply port 500 to host, but work on a copy */
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host = host->clone(host);
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host->set_port(host, ike_cfg->get_my_port(ike_cfg));
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notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
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host->destroy(host);
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if (notify)
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{
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message->add_payload(message, (payload_t*)notify);
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}
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}
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enumerator->destroy(enumerator);
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}
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}
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return NEED_MORE;
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}
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METHOD(task_t, build_r, status_t,
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private_ike_natd_t *this, message_t *message)
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{
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notify_payload_t *notify;
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host_t *me, *other;
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/* only add notifies on successful responses. */
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if (message->get_exchange_type(message) == IKE_SA_INIT &&
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message->get_payload(message, PLV2_SECURITY_ASSOCIATION) == NULL)
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{
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return SUCCESS;
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}
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if (this->src_seen && this->dst_seen)
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{
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if (this->hasher == NULL)
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{
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DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported");
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return SUCCESS;
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}
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/* initiator seems to support NAT detection, add response */
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me = message->get_source(message);
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notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, me);
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if (notify)
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{
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message->add_payload(message, (payload_t*)notify);
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}
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other = message->get_destination(message);
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notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, other);
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if (notify)
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{
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message->add_payload(message, (payload_t*)notify);
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}
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}
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return SUCCESS;
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}
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METHOD(task_t, process_r, status_t,
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private_ike_natd_t *this, message_t *message)
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{
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process_payloads(this, message);
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return NEED_MORE;
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}
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METHOD(task_t, get_type, task_type_t,
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private_ike_natd_t *this)
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{
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return TASK_IKE_NATD;
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}
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METHOD(task_t, migrate, void,
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private_ike_natd_t *this, ike_sa_t *ike_sa)
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{
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this->ike_sa = ike_sa;
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this->src_seen = FALSE;
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this->dst_seen = FALSE;
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this->src_matched = FALSE;
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this->dst_matched = FALSE;
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this->mapping_changed = FALSE;
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}
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METHOD(task_t, destroy, void,
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private_ike_natd_t *this)
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{
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DESTROY_IF(this->hasher);
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free(this);
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}
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METHOD(ike_natd_t, has_mapping_changed, bool,
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private_ike_natd_t *this)
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{
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return this->mapping_changed;
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}
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/*
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* Described in header.
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*/
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ike_natd_t *ike_natd_create(ike_sa_t *ike_sa, bool initiator)
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{
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private_ike_natd_t *this;
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INIT(this,
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.public = {
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.task = {
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.get_type = _get_type,
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.migrate = _migrate,
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.destroy = _destroy,
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},
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.has_mapping_changed = _has_mapping_changed,
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},
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.ike_sa = ike_sa,
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.initiator = initiator,
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.hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1),
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);
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if (initiator)
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{
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this->public.task.build = _build_i;
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this->public.task.process = _process_i;
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}
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else
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{
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this->public.task.build = _build_r;
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this->public.task.process = _process_r;
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}
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return &this->public;
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}
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