302 lines
6.7 KiB
C
302 lines
6.7 KiB
C
/*
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* Copyright (C) 2007 Martin Willi
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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 "eap_md5.h"
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#include <daemon.h>
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#include <library.h>
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#include <crypto/hashers/hasher.h>
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typedef struct private_eap_md5_t private_eap_md5_t;
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/**
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* Private data of an eap_md5_t object.
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*/
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struct private_eap_md5_t {
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/**
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* Public authenticator_t interface.
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*/
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eap_md5_t public;
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/**
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* ID of the server
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*/
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identification_t *server;
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/**
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* ID of the peer
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*/
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identification_t *peer;
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/**
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* challenge sent by the server
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*/
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chunk_t challenge;
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/**
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* EAP message identifier
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*/
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uint8_t identifier;
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};
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typedef struct eap_md5_header_t eap_md5_header_t;
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/**
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* packed eap MD5 header struct
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*/
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struct eap_md5_header_t {
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/** EAP code (REQUEST/RESPONSE) */
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uint8_t code;
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/** unique message identifier */
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uint8_t identifier;
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/** length of whole message */
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uint16_t length;
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/** EAP type */
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uint8_t type;
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/** length of value (challenge) */
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uint8_t value_size;
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/** actual value */
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uint8_t value[];
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} __attribute__((__packed__));
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#define CHALLENGE_LEN 16
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#define PAYLOAD_LEN (CHALLENGE_LEN + sizeof(eap_md5_header_t))
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/**
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* Hash the challenge string, create response
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*/
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static status_t hash_challenge(private_eap_md5_t *this, chunk_t *response,
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identification_t *me, identification_t *other)
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{
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shared_key_t *shared;
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chunk_t concat;
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hasher_t *hasher;
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shared = lib->credmgr->get_shared(lib->credmgr, SHARED_EAP, me, other);
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if (shared == NULL)
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{
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DBG1(DBG_IKE, "no EAP key found for hosts '%Y' - '%Y'", me, other);
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return NOT_FOUND;
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}
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concat = chunk_cata("ccc", chunk_from_thing(this->identifier),
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shared->get_key(shared), this->challenge);
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shared->destroy(shared);
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hasher = lib->crypto->create_hasher(lib->crypto, HASH_MD5);
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if (hasher == NULL)
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{
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DBG1(DBG_IKE, "EAP-MD5 failed, MD5 not supported");
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return FAILED;
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}
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if (!hasher->allocate_hash(hasher, concat, response))
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{
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hasher->destroy(hasher);
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return FAILED;
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}
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hasher->destroy(hasher);
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return SUCCESS;
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}
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METHOD(eap_method_t, initiate_peer, status_t,
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private_eap_md5_t *this, eap_payload_t **out)
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{
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/* peer never initiates */
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return FAILED;
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}
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METHOD(eap_method_t, initiate_server, status_t,
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private_eap_md5_t *this, eap_payload_t **out)
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{
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rng_t *rng;
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eap_md5_header_t *req;
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rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
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if (!rng || !rng->allocate_bytes(rng, CHALLENGE_LEN, &this->challenge))
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{
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DESTROY_IF(rng);
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return FAILED;
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}
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rng->destroy(rng);
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req = alloca(PAYLOAD_LEN);
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req->length = htons(PAYLOAD_LEN);
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req->code = EAP_REQUEST;
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req->identifier = this->identifier;
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req->type = EAP_MD5;
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req->value_size = this->challenge.len;
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memcpy(req->value, this->challenge.ptr, this->challenge.len);
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*out = eap_payload_create_data(chunk_create((void*)req, PAYLOAD_LEN));
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return NEED_MORE;
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}
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METHOD(eap_method_t, process_peer, status_t,
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private_eap_md5_t *this, eap_payload_t *in, eap_payload_t **out)
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{
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chunk_t response;
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chunk_t data;
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eap_md5_header_t *req;
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this->identifier = in->get_identifier(in);
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data = in->get_data(in);
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if (data.len < 6 || data.ptr[5] + 6 > data.len)
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{
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DBG1(DBG_IKE, "received invalid EAP-MD5 message");
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return FAILED;
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}
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this->challenge = chunk_clone(chunk_create(data.ptr + 6, data.ptr[5]));
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if (hash_challenge(this, &response, this->peer, this->server) != SUCCESS)
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{
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return FAILED;
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}
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req = alloca(PAYLOAD_LEN);
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req->length = htons(PAYLOAD_LEN);
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req->code = EAP_RESPONSE;
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req->identifier = this->identifier;
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req->type = EAP_MD5;
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req->value_size = response.len;
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memcpy(req->value, response.ptr, response.len);
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chunk_free(&response);
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*out = eap_payload_create_data(chunk_create((void*)req, PAYLOAD_LEN));
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return NEED_MORE;
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}
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METHOD(eap_method_t, process_server, status_t,
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private_eap_md5_t *this, eap_payload_t *in, eap_payload_t **out)
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{
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chunk_t response, expected;
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chunk_t data;
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data = in->get_data(in);
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if (this->identifier != in->get_identifier(in) ||
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data.len < 6 || data.ptr[5] + 6 > data.len)
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{
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DBG1(DBG_IKE, "received invalid EAP-MD5 message");
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return FAILED;
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}
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if (hash_challenge(this, &expected, this->server, this->peer) != SUCCESS)
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{
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return FAILED;
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}
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response = chunk_create(data.ptr + 6, data.ptr[5]);
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if (response.len < expected.len ||
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!memeq_const(response.ptr, expected.ptr, expected.len))
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{
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chunk_free(&expected);
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DBG1(DBG_IKE, "EAP-MD5 verification failed");
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return FAILED;
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}
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chunk_free(&expected);
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return SUCCESS;
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}
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METHOD(eap_method_t, get_type, eap_type_t,
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private_eap_md5_t *this, uint32_t *vendor)
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{
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*vendor = 0;
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return EAP_MD5;
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}
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METHOD(eap_method_t, get_msk, status_t,
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private_eap_md5_t *this, chunk_t *msk)
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{
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return FAILED;
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}
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METHOD(eap_method_t, is_mutual, bool,
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private_eap_md5_t *this)
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{
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return FALSE;
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}
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METHOD(eap_method_t, get_identifier, uint8_t,
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private_eap_md5_t *this)
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{
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return this->identifier;
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}
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METHOD(eap_method_t, set_identifier, void,
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private_eap_md5_t *this, uint8_t identifier)
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{
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this->identifier = identifier;
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}
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METHOD(eap_method_t, destroy, void,
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private_eap_md5_t *this)
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{
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this->peer->destroy(this->peer);
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this->server->destroy(this->server);
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chunk_free(&this->challenge);
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free(this);
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}
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/*
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* See header
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*/
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eap_md5_t *eap_md5_create_server(identification_t *server, identification_t *peer)
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{
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private_eap_md5_t *this;
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INIT(this,
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.public = {
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.eap_method = {
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.initiate = _initiate_server,
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.process = _process_server,
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.get_type = _get_type,
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.is_mutual = _is_mutual,
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.get_msk = _get_msk,
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.get_identifier = _get_identifier,
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.set_identifier = _set_identifier,
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.destroy = _destroy,
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},
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},
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.peer = peer->clone(peer),
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.server = server->clone(server),
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);
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/* generate a non-zero identifier */
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do {
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this->identifier = random();
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} while (!this->identifier);
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return &this->public;
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}
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/*
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* See header
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*/
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eap_md5_t *eap_md5_create_peer(identification_t *server, identification_t *peer)
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{
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private_eap_md5_t *this;
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INIT(this,
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.public = {
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.eap_method = {
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.initiate = _initiate_peer,
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.process = _process_peer,
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.get_type = _get_type,
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.is_mutual = _is_mutual,
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.get_msk = _get_msk,
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.destroy = _destroy,
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},
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},
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.peer = peer->clone(peer),
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.server = server->clone(server),
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);
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return &this->public;
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}
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