- Updated to new upstream.

1 files changed, 1540 insertions, 0 deletions

diff --git a/src/charon/credentials/credential_manager.c b/src/charon/credentials/credential_manager.c
new file mode 100644
index 000000000..251559141
--- /dev/null
+++ b/src/charon/credentials/credential_manager.c
@@ -0,0 +1,1540 @@
+/*
+ * Copyright (C) 2007 Martin Willi
+ * 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.
+ *
+ * $Id: credential_manager.c 3953 2008-05-14 06:49:31Z martin $
+ */
+
+/* some clibs need it for rwlocks */
+#define _GNU_SOURCE
+#include <pthread.h>
+
+#include "credential_manager.h"
+
+#include <daemon.h>
+#include <utils/linked_list.h>
+#include <credentials/sets/cert_cache.h>
+#include <credentials/sets/auth_info_wrapper.h>
+#include <credentials/sets/ocsp_response_wrapper.h>
+#include <credentials/certificates/x509.h>
+#include <credentials/certificates/crl.h>
+#include <credentials/certificates/ocsp_request.h>
+#include <credentials/certificates/ocsp_response.h>
+
+#define MAX_CA_LEVELS 6
+
+typedef struct private_credential_manager_t private_credential_manager_t;
+
+/**
+ * private data of credential_manager
+ */
+struct private_credential_manager_t {
+
+	/**
+	 * public functions
+	 */
+	credential_manager_t public;
+	
+	/**
+	 * list of credential sets
+	 */
+	linked_list_t *sets;
+	
+	/**
+	 * thread local set of credentials, linked_list_t with credential_set_t's
+	 */
+	pthread_key_t local_sets;
+	
+	/**
+	 * trust relationship and certificate cache
+	 */
+	cert_cache_t *cache;
+	
+	/**
+	 * read-write lock to sets list
+	 */
+	pthread_rwlock_t lock;
+};
+
+/** data to pass to create_private_enumerator */
+typedef struct {
+	private_credential_manager_t *this;
+	key_type_t type;
+	identification_t* keyid;
+} private_data_t;
+
+/** data to pass to create_cert_enumerator */
+typedef struct {
+	private_credential_manager_t *this;
+	certificate_type_t cert;
+	key_type_t key;
+	identification_t *id;
+	bool trusted;
+} cert_data_t;
+
+/** data to pass to create_cdp_enumerator */
+typedef struct {
+	private_credential_manager_t *this;
+	certificate_type_t type;
+	identification_t *id;
+} cdp_data_t;
+
+/** data to pass to create_shared_enumerator */
+typedef struct {
+	private_credential_manager_t *this;
+	shared_key_type_t type;
+	identification_t *me;
+	identification_t *other;
+} shared_data_t;
+
+/** enumerator over local and global sets */
+typedef struct {
+	/** implements enumerator_t */
+	enumerator_t public;
+	/** enumerator over global sets */
+	enumerator_t *global;
+	/** enumerator over local sets */
+	enumerator_t *local;
+} sets_enumerator_t;
+
+/**
+ * destroy a sets_enumerator_t
+ */
+static void sets_enumerator_destroy(sets_enumerator_t *this)
+{
+	DESTROY_IF(this->global);
+	DESTROY_IF(this->local);
+	free(this);
+}
+
+/**
+ * sets_enumerator_t.enumerate
+ */
+static bool sets_enumerator_enumerate(sets_enumerator_t *this,
+									  credential_set_t **set)
+{
+	if (this->global)
+	{
+		if (this->global->enumerate(this->global, set))
+		{
+			return TRUE;
+		}
+		/* end of global sets, look for local */
+		this->global->destroy(this->global);
+		this->global = NULL;
+	}
+	if (this->local)
+	{
+		return this->local->enumerate(this->local, set);
+	}
+	return FALSE;
+}
+
+/**
+ * create an enumerator over both, global and local sets
+ */
+static enumerator_t *create_sets_enumerator(private_credential_manager_t *this)
+{
+	linked_list_t *local;
+	sets_enumerator_t *enumerator = malloc_thing(sets_enumerator_t);
+	
+	enumerator->public.enumerate = (void*)sets_enumerator_enumerate;
+	enumerator->public.destroy = (void*)sets_enumerator_destroy;
+	enumerator->global = this->sets->create_enumerator(this->sets);
+	enumerator->local = NULL;
+	local = pthread_getspecific(this->local_sets);
+	if (local)
+	{
+		enumerator->local = local->create_enumerator(local);
+	}
+	return &enumerator->public;
+}
+
+/**
+ * cleanup function for cert data
+ */
+static void destroy_cert_data(cert_data_t *data)
+{
+	pthread_rwlock_unlock(&data->this->lock);
+	free(data);
+}
+
+/**
+ * enumerator constructor for certificates
+ */
+static enumerator_t *create_cert(credential_set_t *set, cert_data_t *data)
+{
+	return set->create_cert_enumerator(set, data->cert, data->key, 
+									   data->id, data->trusted);
+}
+
+/**
+ * Implementation of credential_manager_t.create_cert_enumerator.
+ */
+static enumerator_t *create_cert_enumerator(private_credential_manager_t *this,
+						certificate_type_t certificate, key_type_t key,
+						identification_t *id, bool trusted)
+{
+	cert_data_t *data = malloc_thing(cert_data_t);
+	data->this = this;
+	data->cert = certificate;
+	data->key = key;
+	data->id = id;
+	data->trusted = trusted;
+	
+	pthread_rwlock_rdlock(&this->lock);
+	return enumerator_create_nested(create_sets_enumerator(this),
+									(void*)create_cert, data,
+									(void*)destroy_cert_data);
+}
+
+/**
+ * Implementation of credential_manager_t.get_cert.
+ */
+static certificate_t *get_cert(private_credential_manager_t *this,
+						certificate_type_t cert, key_type_t key,
+						identification_t *id, bool trusted)
+{
+	certificate_t *current, *found = NULL;
+	enumerator_t *enumerator;
+	
+	enumerator = create_cert_enumerator(this, cert, key, id, trusted);
+	if (enumerator->enumerate(enumerator, &current))
+	{
+		/* TODO: best match? order by keyid, subject, sualtname */
+		found = current->get_ref(current);
+	}
+	enumerator->destroy(enumerator);
+	return found;
+}
+
+
+/**
+ * cleanup function for cdp data
+ */
+static void destroy_cdp_data(cdp_data_t *data)
+{
+	pthread_rwlock_unlock(&data->this->lock);
+	free(data);
+}
+
+/**
+ * enumerator constructor for CDPs
+ */
+static enumerator_t *create_cdp(credential_set_t *set, cdp_data_t *data)
+{
+	return set->create_cdp_enumerator(set, data->type, data->id);
+}
+/**
+ * Implementation of credential_manager_t.create_cdp_enumerator.
+ */
+static enumerator_t * create_cdp_enumerator(private_credential_manager_t *this,
+								certificate_type_t type, identification_t *id)
+{
+	cdp_data_t *data = malloc_thing(cdp_data_t);
+	data->this = this;
+	data->type = type;
+	data->id = id;
+	
+	pthread_rwlock_rdlock(&this->lock);
+	return enumerator_create_nested(create_sets_enumerator(this),
+									(void*)create_cdp, data,
+									(void*)destroy_cdp_data);
+}
+
+/**
+ * cleanup function for private data
+ */
+static void destroy_private_data(private_data_t *data)
+{
+	pthread_rwlock_unlock(&data->this->lock);
+	free(data);
+}
+
+/**
+ * enumerator constructor for private keys
+ */
+static enumerator_t *create_private(credential_set_t *set, private_data_t *data)
+{
+	return set->create_private_enumerator(set, data->type, data->keyid);
+}
+
+/**
+ * Implementation of credential_manager_t.get_private_by_keyid.
+ */
+static enumerator_t* create_private_enumerator(
+									private_credential_manager_t *this,
+								    key_type_t key, identification_t *keyid)
+{
+	private_data_t *data;
+	
+	data = malloc_thing(private_data_t);
+	data->this = this;
+	data->type = key;
+	data->keyid = keyid;
+	pthread_rwlock_rdlock(&this->lock);
+	return enumerator_create_nested(create_sets_enumerator(this),
+									(void*)create_private, data,
+									(void*)destroy_private_data);
+}
+
+/**
+ * Implementation of credential_manager_t.get_private_by_keyid.
+ */   
+static private_key_t *get_private_by_keyid(private_credential_manager_t *this,
+										   key_type_t key, identification_t *keyid)
+{
+	private_key_t *found = NULL;
+	enumerator_t *enumerator;
+	
+	enumerator = create_private_enumerator(this, key, keyid);
+	if (enumerator->enumerate(enumerator, &found))
+	{
+		found->get_ref(found);
+	}
+	enumerator->destroy(enumerator);
+	return found;
+}
+
+/**
+ * cleanup function for shared data
+ */
+static void destroy_shared_data(shared_data_t *data)
+{
+	pthread_rwlock_unlock(&data->this->lock);
+	free(data);
+}
+
+/**
+ * enumerator constructor for shared keys
+ */
+static enumerator_t *create_shared(credential_set_t *set, shared_data_t *data)
+{
+	return set->create_shared_enumerator(set, data->type, data->me, data->other);
+}
+
+/**
+ * Implementation of credential_manager_t.create_shared_enumerator.
+ */
+static enumerator_t *create_shared_enumerator(private_credential_manager_t *this, 
+						shared_key_type_t type,
+						identification_t *me, identification_t *other)
+{
+	shared_data_t *data = malloc_thing(shared_data_t);
+	data->this = this;
+	data->type = type;
+	data->me = me;
+	data->other = other;
+	
+	pthread_rwlock_rdlock(&this->lock);
+	return enumerator_create_nested(create_sets_enumerator(this),
+									(void*)create_shared, data, 
+									(void*)destroy_shared_data);
+}
+
+/**
+ * Implementation of credential_manager_t.get_shared.
+ */   
+static shared_key_t *get_shared(private_credential_manager_t *this,
+								shared_key_type_t type,	identification_t *me,
+								identification_t *other)
+{
+	shared_key_t *current, *found = NULL;
+	id_match_t *best_me = ID_MATCH_NONE, *best_other = ID_MATCH_NONE;
+	id_match_t *match_me, *match_other;
+	enumerator_t *enumerator;
+	
+	enumerator = create_shared_enumerator(this, type, me, other);
+	while (enumerator->enumerate(enumerator, &current, &match_me, &match_other))
+	{
+		if (match_other > best_other ||
+			(match_other == best_other && match_me > best_me))
+		{
+			DESTROY_IF(found);
+			found = current->get_ref(current);
+			best_me = match_me;
+			best_other = match_other;
+		}
+	}
+	enumerator->destroy(enumerator);
+	return found;
+}
+
+/**
+ * add a credential set to the thread local list
+ */
+static void add_local_set(private_credential_manager_t *this,
+						  credential_set_t *set)
+{
+	linked_list_t *sets;
+
+	sets = pthread_getspecific(this->local_sets);
+	if (!sets)
+	{	/* first invocation */
+		sets = linked_list_create();
+		pthread_setspecific(this->local_sets, sets);
+	}
+	sets->insert_last(sets, set);
+}
+
+/**
+ * remove a credential set from the thread local list
+ */
+static void remove_local_set(private_credential_manager_t *this,
+							 credential_set_t *set)
+{
+	linked_list_t *sets;
+	
+	sets = pthread_getspecific(this->local_sets);
+	sets->remove(sets, set, NULL);
+}
+
+/**
+ * Implementation of credential_manager_t.cache_cert.
+ */
+static void cache_cert(private_credential_manager_t *this, certificate_t *cert)
+{
+	credential_set_t *set;
+	enumerator_t *enumerator;
+	
+	pthread_rwlock_rdlock(&this->lock);
+	enumerator = this->sets->create_enumerator(this->sets);
+	while (enumerator->enumerate(enumerator, &set))
+	{
+		set->cache_cert(set, cert);
+	}
+	enumerator->destroy(enumerator);
+	pthread_rwlock_unlock(&this->lock);
+}
+
+/**
+ * forward declaration 
+ */
+static enumerator_t *create_trusted_enumerator(private_credential_manager_t *this,
+					key_type_t type, identification_t *id, bool crl, bool ocsp);
+
+/**
+ * Do an OCSP request
+ */
+static certificate_t *fetch_ocsp(private_credential_manager_t *this, char *url,
+								 certificate_t *subject, certificate_t *issuer)
+{
+	certificate_t *request, *response;
+	chunk_t send, receive;
+	
+	/* TODO: requestor name, signature */
+	request = lib->creds->create(lib->creds,
+						CRED_CERTIFICATE, CERT_X509_OCSP_REQUEST,
+						BUILD_CA_CERT, issuer->get_ref(issuer),
+						BUILD_CERT, subject->get_ref(subject), BUILD_END);
+	if (!request)
+	{
+		DBG1(DBG_CFG, "generating ocsp request failed");
+		return NULL;
+	}
+	
+	send = request->get_encoding(request);
+	request->destroy(request);
+
+	DBG1(DBG_CFG, "  requesting ocsp status from '%s' ...", url);
+	if (lib->fetcher->fetch(lib->fetcher, url, &receive, 
+							FETCH_REQUEST_DATA, send,
+							FETCH_REQUEST_TYPE, "application/ocsp-request",
+							FETCH_END) != SUCCESS)
+	{
+		DBG1(DBG_CFG, "ocsp request to %s failed", url);
+		chunk_free(&send);
+		return NULL;
+	}
+	chunk_free(&send);
+	
+	response = lib->creds->create(lib->creds,
+								  CRED_CERTIFICATE, CERT_X509_OCSP_RESPONSE,
+								  BUILD_BLOB_ASN1_DER, receive, BUILD_END);
+	if (!response)
+	{
+		DBG1(DBG_CFG, "parsing ocsp response failed");
+		return NULL;
+	}
+	return response;
+}
+
+/**
+ * check the signature of an OCSP response 
+ */
+static bool verify_ocsp(private_credential_manager_t *this, 
+						ocsp_response_t *response)
+{
+	certificate_t *issuer, *subject;
+	identification_t *responder;
+	ocsp_response_wrapper_t *wrapper;
+	enumerator_t *enumerator;
+	bool verified = FALSE;
+
+	wrapper = ocsp_response_wrapper_create((ocsp_response_t*)response);
+	add_local_set(this, &wrapper->set);
+	
+	subject = &response->certificate;
+	responder = subject->get_issuer(subject);
+	enumerator = create_trusted_enumerator(this, KEY_ANY, responder, FALSE, FALSE);
+	while (enumerator->enumerate(enumerator, &issuer, NULL))
+	{
+		if (this->cache->issued_by(this->cache, subject, issuer))
+		{
+			DBG1(DBG_CFG, "  ocsp response correctly signed by \"%D\"",
+						     issuer->get_subject(issuer));
+			verified = TRUE;
+			break;
+		}
+	}
+	enumerator->destroy(enumerator);
+	
+	remove_local_set(this, &wrapper->set);
+	wrapper->destroy(wrapper);
+	return verified;
+}
+
+/**
+ * Get the better of two OCSP responses, and check for usable OCSP info
+ */
+static certificate_t *get_better_ocsp(private_credential_manager_t *this,
+									  certificate_t *cand, certificate_t *best,
+									  x509_t *subject, x509_t *issuer,
+									  cert_validation_t *valid, bool cache)
+{
+	ocsp_response_t *response;
+	time_t revocation, this_update, next_update, valid_until;
+	crl_reason_t reason;
+	bool revoked = FALSE;
+	
+	response = (ocsp_response_t*)cand;
+
+	/* check ocsp signature */
+	if (!verify_ocsp(this, response))
+	{
+		DBG1(DBG_CFG, "ocsp response verification failed");
+		cand->destroy(cand);
+		return best;
+	}
+	/* check if response contains our certificate */
+	switch (response->get_status(response, subject, issuer, &revocation, &reason,
+								 &this_update, &next_update))
+	{
+		case VALIDATION_REVOKED:
+			/* subject has been revoked by a valid OCSP response */
+			DBG1(DBG_CFG, "certificate was revoked on %T, reason: %N",
+				 		  &revocation, crl_reason_names, reason);
+			revoked = TRUE;
+			break;
+		case VALIDATION_GOOD:
+			/* results in either good or stale */
+			break;
+		default:
+		case VALIDATION_FAILED:
+			/* candidate unusable, does not contain our cert */
+			DBG1(DBG_CFG, "  ocsp response contains no status on our certificate");
+			cand->destroy(cand);
+			return best;
+	}
+
+	/* select the better of the two responses */
+	if (best == NULL || cand->is_newer(cand, best))
+	{
+		DESTROY_IF(best);
+		best = cand;
+		if (best->get_validity(best, NULL, NULL, &valid_until))
+		{
+			DBG1(DBG_CFG, "  ocsp response is valid: until %#T",
+							 &valid_until, FALSE);
+			*valid = VALIDATION_GOOD;
+			if (cache)
+			{	/* cache non-stale only, stale certs get refetched */
+				cache_cert(this, best);
+			}
+		}
+		else
+		{
+			DBG1(DBG_CFG, "  ocsp response is stale: since %#T",
+							 &valid_until, FALSE);
+			*valid = VALIDATION_STALE;
+		}
+	}
+	else
+	{
+		*valid = VALIDATION_STALE;
+		cand->destroy(cand);
+	}
+	if (revoked)
+	{	/* revoked always counts, even if stale */
+		*valid = VALIDATION_REVOKED;
+	}
+	return best;
+}
+
+/**
+ * validate a x509 certificate using OCSP
+ */
+static cert_validation_t check_ocsp(private_credential_manager_t *this,
+								    x509_t *subject, x509_t *issuer, 
+								    auth_info_t *auth)
+{
+	enumerator_t *enumerator;
+	cert_validation_t valid = VALIDATION_SKIPPED;
+	certificate_t *best = NULL, *current;
+	identification_t *keyid = NULL;
+	public_key_t *public;
+	char *uri = NULL;
+
+	/** lookup cache for valid OCSP responses */
+	enumerator = create_cert_enumerator(this, CERT_X509_OCSP_RESPONSE,
+										KEY_ANY, NULL, FALSE);
+	while (enumerator->enumerate(enumerator, &current))
+	{
+		current->get_ref(current);
+		best = get_better_ocsp(this, current, best, subject, issuer,
+							   &valid, FALSE);
+		if (best && valid != VALIDATION_STALE)
+		{
+			DBG1(DBG_CFG, "  using cached ocsp response");
+			break;
+		}
+	}
+	enumerator->destroy(enumerator);
+
+	/* derive the authorityKeyIdentifier from the issuer's public key */
+	current = &issuer->interface;
+	public = current->get_public_key(current);
+	if (public)
+	{
+		keyid = public->get_id(public, ID_PUBKEY_SHA1);
+	}
+	/** fetch from configured OCSP responder URLs */
+	if (keyid && valid != VALIDATION_GOOD && valid != VALIDATION_REVOKED)
+	{
+		enumerator = create_cdp_enumerator(this, CERT_X509_OCSP_RESPONSE, keyid);
+		while (enumerator->enumerate(enumerator, &uri))
+		{
+			current = fetch_ocsp(this, uri, &subject->interface,
+								 &issuer->interface);
+			if (current)
+			{
+				best = get_better_ocsp(this, current, best, subject, issuer,
+									   &valid, TRUE);
+				if (best && valid != VALIDATION_STALE)
+				{
+					break;
+				}
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+	DESTROY_IF(public);
+
+	/* fallback to URL fetching from subject certificate's URIs */
+	if (valid != VALIDATION_GOOD && valid != VALIDATION_REVOKED)
+	{
+		enumerator = subject->create_ocsp_uri_enumerator(subject);
+		while (enumerator->enumerate(enumerator, &uri))
+		{
+			current = fetch_ocsp(this, uri, &subject->interface,
+								 &issuer->interface);
+			if (current)
+			{
+				best = get_better_ocsp(this, current, best, subject, issuer,
+									   &valid, TRUE);
+				if (best && valid != VALIDATION_STALE)
+				{
+					break;
+				}
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+	/* an uri was found, but no result. switch validation state to failed */
+	if (valid == VALIDATION_SKIPPED && uri)
+	{
+		valid = VALIDATION_FAILED;
+	}
+	if (auth)
+	{
+		auth->add_item(auth, AUTHZ_OCSP_VALIDATION, &valid);
+	}
+	DESTROY_IF(best);
+	return valid;
+}
+
+/**
+ * fetch a CRL from an URL
+ */
+static certificate_t* fetch_crl(private_credential_manager_t *this, char *url)
+{
+	certificate_t *crl;
+	chunk_t chunk;
+	
+	DBG1(DBG_CFG, "  fetching crl from '%s' ...", url);
+	if (lib->fetcher->fetch(lib->fetcher, url, &chunk, FETCH_END) != SUCCESS)
+	{
+		DBG1(DBG_CFG, "crl fetching failed");
+		return NULL;
+	}
+	crl = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509_CRL,
+							 BUILD_BLOB_ASN1_DER, chunk, BUILD_END);
+	if (!crl)
+	{
+		DBG1(DBG_CFG, "crl fetched successfully but parsing failed");
+		return NULL;
+	}
+	return crl;
+}
+
+/**
+ * check the signature of an CRL
+ */
+static bool verify_crl(private_credential_manager_t *this, certificate_t *crl)
+{
+	certificate_t *issuer;
+	enumerator_t *enumerator;
+	bool verified = FALSE;
+	
+	enumerator = create_trusted_enumerator(this, KEY_ANY, crl->get_issuer(crl),
+										   FALSE, FALSE);
+	while (enumerator->enumerate(enumerator, &issuer, NULL))
+	{
+		if (this->cache->issued_by(this->cache, crl, issuer))
+		{
+			DBG1(DBG_CFG, "  crl correctly signed by \"%D\"",
+						   issuer->get_subject(issuer));
+			verified = TRUE;
+			break;
+		}
+	}
+	enumerator->destroy(enumerator);
+	
+	return verified;
+}
+
+/**
+ * Get the better of two CRLs, and check for usable CRL info
+ */
+static certificate_t *get_better_crl(private_credential_manager_t *this,
+									 certificate_t *cand, certificate_t *best,
+									 x509_t *subject, x509_t *issuer,
+									 cert_validation_t *valid, bool cache)
+{
+	enumerator_t *enumerator;
+	time_t revocation, valid_until;
+	crl_reason_t reason;
+	chunk_t serial;
+	crl_t *crl;
+
+	/* check CRL signature */
+	if (!verify_crl(this, cand))
+	{
+		DBG1(DBG_CFG, "crl response verification failed");
+		cand->destroy(cand);
+		return best;
+	}
+	
+	crl = (crl_t*)cand;
+	enumerator = crl->create_enumerator(crl);
+	while (enumerator->enumerate(enumerator, &serial, &revocation, &reason))
+	{
+		if (chunk_equals(serial, subject->get_serial(subject)))
+		{
+			DBG1(DBG_CFG, "certificate was revoked on %T, reason: %N",
+				 &revocation, crl_reason_names, reason);
+			*valid = VALIDATION_REVOKED;
+			enumerator->destroy(enumerator);
+			DESTROY_IF(best);
+			return cand;
+		}
+	}
+	enumerator->destroy(enumerator);
+
+	/* select the better of the two CRLs */
+	if (best == NULL || cand->is_newer(cand, best))
+	{
+		DESTROY_IF(best);
+		best = cand;
+		if (best->get_validity(best, NULL, NULL, &valid_until))
+		{
+			DBG1(DBG_CFG, "  crl is valid: until %#T", &valid_until, FALSE);
+			*valid = VALIDATION_GOOD;
+			if (cache)
+			{	/* we cache non-stale crls only, as a stale crls are refetched */
+				cache_cert(this, best);
+			}
+		}
+		else
+		{
+			DBG1(DBG_CFG, "  crl is stale: since %#T", &valid_until, FALSE);
+			*valid = VALIDATION_STALE;
+		}
+	}
+	else
+	{
+		*valid = VALIDATION_STALE;
+		cand->destroy(cand);
+	}
+	return best;
+}
+
+/**
+ * validate a x509 certificate using CRL
+ */
+static cert_validation_t check_crl(private_credential_manager_t *this,
+								   x509_t *subject, x509_t *issuer, 
+								   auth_info_t *auth)
+{
+	cert_validation_t valid = VALIDATION_SKIPPED;
+	identification_t *keyid = NULL;
+	certificate_t *best = NULL;
+	certificate_t *current;
+	public_key_t *public;
+	enumerator_t *enumerator;
+	char *uri;
+	
+	/* derive the authorityKeyIdentifier from the issuer's public key */
+	current = &issuer->interface;
+	public = current->get_public_key(current);
+	if (public)
+	{
+		keyid = public->get_id(public, ID_PUBKEY_SHA1);
+	}
+	
+	/* find a cached crl by authorityKeyIdentifier */
+	if (keyid)
+	{
+		enumerator = create_cert_enumerator(this, CERT_X509_CRL, KEY_ANY, 
+											keyid, FALSE);
+		while (enumerator->enumerate(enumerator, &current))
+		{
+			current->get_ref(current);
+			best = get_better_crl(this, current, best, subject, issuer,
+								  &valid, FALSE);
+			if (best && valid != VALIDATION_STALE)
+			{
+				DBG1(DBG_CFG, "  using cached crl");
+				break;
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+
+	/* fallback to fetching crls from credential sets cdps */
+	if (keyid && valid != VALIDATION_GOOD && valid != VALIDATION_REVOKED)
+	{
+		enumerator = create_cdp_enumerator(this, CERT_X509_CRL, keyid);
+
+		while (enumerator->enumerate(enumerator, &uri))
+		{
+			current = fetch_crl(this, uri);
+			if (current)
+			{
+				best = get_better_crl(this, current, best, subject, issuer,
+									  &valid, TRUE);
+				if (best && valid != VALIDATION_STALE)
+				{
+					break;
+				}
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+	DESTROY_IF(public);
+
+	/* fallback to fetching crls from cdps from subject's certificate */
+	if (valid != VALIDATION_GOOD && valid != VALIDATION_REVOKED)
+	{
+		enumerator = subject->create_crl_uri_enumerator(subject);
+
+		while (enumerator->enumerate(enumerator, &uri))
+		{
+			current = fetch_crl(this, uri);
+			if (current)
+			{
+				best = get_better_crl(this, current, best, subject, issuer,
+									  &valid, TRUE);
+				if (best && valid != VALIDATION_STALE)
+				{
+					break;
+				}
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+	
+	/* an uri was found, but no result. switch validation state to failed */
+	if (valid == VALIDATION_SKIPPED && uri)
+	{
+		valid = VALIDATION_FAILED;
+	}
+	if (auth)
+	{
+		auth->add_item(auth, AUTHZ_CRL_VALIDATION, &valid);
+	}
+	DESTROY_IF(best);
+	return valid;
+}
+
+/**
+ * check a certificate for its lifetime
+ */
+static bool check_certificate(private_credential_manager_t *this,
+							  certificate_t *subject, certificate_t *issuer,
+							  bool crl, bool ocsp, auth_info_t *auth)
+{
+	time_t not_before, not_after;
+	
+	if (!subject->get_validity(subject, NULL, &not_before, &not_after))
+	{
+		DBG1(DBG_CFG, "subject certificate invalid (valid from %T to %T)",
+			 &not_before, &not_after);
+		return FALSE;
+	}
+	if (!issuer->get_validity(issuer, NULL, &not_before, &not_after))
+	{
+		DBG1(DBG_CFG, "issuer certificate invalid (valid from %T to %T)",
+			 &not_before, &not_after);
+		return FALSE;
+	}
+	if (issuer->get_type(issuer) == CERT_X509 &&
+		subject->get_type(subject) == CERT_X509)
+	{
+		if (ocsp || crl)
+		{
+			DBG1(DBG_CFG, "checking certificate status of \"%D\"",
+						   subject->get_subject(subject));
+		}
+		if (ocsp)
+		{
+			switch (check_ocsp(this, (x509_t*)subject, (x509_t*)issuer, auth))
+			{
+				case VALIDATION_GOOD:
+					DBG1(DBG_CFG, "certificate status is good");
+					return TRUE;
+				case VALIDATION_REVOKED:
+					/* has already been logged */			
+					return FALSE;
+				case VALIDATION_SKIPPED:
+					DBG2(DBG_CFG, "ocsp check skipped, no ocsp found");
+					break;
+				case VALIDATION_STALE:
+					DBG1(DBG_CFG, "ocsp information stale, fallback to crl");
+					break;
+				case VALIDATION_FAILED:
+					DBG1(DBG_CFG, "ocsp check failed, fallback to crl");
+					break;
+			}
+		}
+		if (crl)
+		{
+			switch (check_crl(this, (x509_t*)subject, (x509_t*)issuer, auth))
+			{
+				case VALIDATION_GOOD:
+					DBG1(DBG_CFG, "certificate status is good");
+					return TRUE;
+				case VALIDATION_REVOKED:		
+					/* has already been logged */			
+					return FALSE;
+				case VALIDATION_FAILED:
+				case VALIDATION_SKIPPED:
+					DBG1(DBG_CFG, "certificate status is not available");
+					break;
+				case VALIDATION_STALE:
+					DBG1(DBG_CFG, "certificate status is unknown, crl is stale");
+					break;
+			}
+		}
+	}
+	return TRUE;
+}
+
+/**
+ * Get a trusted certificate from a credential set
+ */
+static certificate_t *get_pretrusted_cert(private_credential_manager_t *this,
+										  key_type_t type, identification_t *id)
+{
+	certificate_t *subject;
+	public_key_t *public;
+	
+	subject = get_cert(this, CERT_ANY, type, id, TRUE);
+	if (!subject)
+	{
+		return NULL;
+	}
+	public = subject->get_public_key(subject);
+	if (!public)
+	{
+		subject->destroy(subject);
+		return NULL;
+	}
+	public->destroy(public);
+	return subject;
+}
+
+/**
+ * Get the issuing certificate of a subject certificate
+ */
+static certificate_t *get_issuer_cert(private_credential_manager_t *this,
+									  certificate_t *subject, bool trusted)
+{
+	enumerator_t *enumerator;
+	certificate_t *issuer = NULL, *candidate;
+	
+	enumerator = create_cert_enumerator(this, subject->get_type(subject), KEY_ANY, 
+										subject->get_issuer(subject), trusted);
+	while (enumerator->enumerate(enumerator, &candidate))
+	{
+		if (this->cache->issued_by(this->cache, subject, candidate))
+		{
+			issuer = candidate->get_ref(candidate);
+			break;
+		}
+	}
+	enumerator->destroy(enumerator);
+	return issuer;
+}
+
+/**
+ * try to verify the trust chain of subject, return TRUE if trusted
+ */
+static bool verify_trust_chain(private_credential_manager_t *this,
+							   certificate_t *subject, auth_info_t *result,
+							   bool trusted, bool crl, bool ocsp)
+{
+	certificate_t *current, *issuer;
+	auth_info_t *auth;
+	u_int level = 0;
+	
+	auth = auth_info_create();
+	current = subject->get_ref(subject);
+	while (level++ < MAX_CA_LEVELS)
+	{
+		issuer = get_issuer_cert(this, current, TRUE);
+		if (issuer)
+		{
+			/* accept only self-signed CAs as trust anchor */
+			if (this->cache->issued_by(this->cache, issuer, issuer))
+			{
+				auth->add_item(auth, AUTHZ_CA_CERT, issuer);
+				DBG1(DBG_CFG, "  using trusted ca certificate \"%D\"",
+					 issuer->get_subject(issuer));
+				trusted = TRUE;
+			}
+			else
+			{
+				auth->add_item(auth, AUTHZ_IM_CERT, issuer);
+				DBG1(DBG_CFG, "  using trusted intermediate ca certificate "
+					 "\"%D\"", issuer->get_subject(issuer));
+			}
+		}
+		else
+		{
+			issuer = get_issuer_cert(this, current, FALSE);
+			if (issuer)
+			{
+				if (current->equals(current, issuer))
+				{
+					DBG1(DBG_CFG, "  self-signed certificate \"%D\" is not trusted",
+						 current->get_subject(current));
+					issuer->destroy(issuer);
+					break;
+				}
+				auth->add_item(auth, AUTHZ_IM_CERT, issuer);
+				DBG1(DBG_CFG, "  using untrusted intermediate certificate "
+					 "\"%D\"", issuer->get_subject(issuer));
+			}
+			else
+			{
+				DBG1(DBG_CFG, "no issuer certificate found for \"%D\"", 
+					 current->get_subject(current));
+				break;
+			}
+		}
+		if (!check_certificate(this, current, issuer, crl, ocsp,
+							   current == subject ? auth : NULL))
+		{
+			trusted = FALSE;
+			issuer->destroy(issuer);
+			break;
+		}
+		current->destroy(current);
+		current = issuer;
+		if (trusted)
+		{
+			break;
+		}
+	}
+	current->destroy(current);
+	if (level > MAX_CA_LEVELS)
+	{
+		DBG1(DBG_CFG, "maximum ca path length of %d levels reached", level);
+	}
+	if (trusted)
+	{
+		result->merge(result, auth);
+	}
+	auth->destroy(auth);
+	return trusted;
+}
+
+/**
+ * enumerator for trusted certificates
+ */
+typedef struct {
+	/** implements enumerator_t interface */
+	enumerator_t public;
+	/** enumerator over candidate peer certificates */
+	enumerator_t *candidates;
+	/** reference to the credential_manager */
+	private_credential_manager_t *this;
+	/** type of the requested key */
+	key_type_t type;
+	/** identity the requested key belongs to */
+	identification_t *id;
+	/** TRUE to do CRL checking */
+	bool crl;
+	/** TRUE to do OCSP checking */
+	bool ocsp;
+	/** pretrusted certificate we have served at first invocation */
+	certificate_t *pretrusted;
+	/** currently enumerating auth info */
+	auth_info_t *auth;
+} trusted_enumerator_t;
+
+/**
+ * Implements trusted_enumerator_t.enumerate
+ */
+static bool trusted_enumerate(trusted_enumerator_t *this,
+							  certificate_t **cert, auth_info_t **auth)
+{
+	certificate_t *current;
+	
+	DESTROY_IF(this->auth);
+	this->auth = auth_info_create();
+	
+	if (!this->candidates)
+	{
+		/* first invocation, build enumerator for next one */
+		this->candidates = create_cert_enumerator(this->this, CERT_ANY,
+												  this->type, this->id, FALSE);
+		/* check if we have a trusted certificate for that peer */
+		this->pretrusted = get_pretrusted_cert(this->this, this->type, this->id);
+		if (this->pretrusted)
+		{
+			/* if we find a trusted self signed certificate, we just accept it.
+			 * However, in order to fulfill authorization rules, we try to build 
+			 * the trust chain if it is not self signed */
+			if (this->this->cache->issued_by(this->this->cache,
+								   this->pretrusted, this->pretrusted) ||
+				verify_trust_chain(this->this, this->pretrusted, this->auth,
+								   TRUE, this->crl, this->ocsp))
+			{
+				DBG1(DBG_CFG, "  using trusted certificate \"%D\"",
+					 this->pretrusted->get_subject(this->pretrusted));
+				*cert = this->pretrusted;
+				if (auth)
+				{
+					*auth = this->auth;
+				}
+				return TRUE;
+			}
+		}
+	}
+	/* try to verify the trust chain for each certificate found */
+	while (this->candidates->enumerate(this->candidates, &current))
+	{
+		if (this->pretrusted &&
+			this->pretrusted->equals(this->pretrusted, current))
+		{	/* skip pretrusted certificate we already served */
+			continue;
+		}
+	
+		DBG1(DBG_CFG, "  using certificate \"%D\"",
+			 current->get_subject(current));
+		if (verify_trust_chain(this->this, current, this->auth, FALSE,
+							   this->crl, this->ocsp))
+		{
+			*cert = current;
+			if (auth)
+			{
+				*auth = this->auth;
+			}
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+/**
+ * Implements trusted_enumerator_t.destroy
+ */
+static void trusted_destroy(trusted_enumerator_t *this)
+{
+	DESTROY_IF(this->pretrusted);
+	DESTROY_IF(this->auth);
+	DESTROY_IF(this->candidates);
+	free(this);
+}
+
+/**
+ * create an enumerator over trusted certificates and their trustchain
+ */
+static enumerator_t *create_trusted_enumerator(private_credential_manager_t *this,
+					key_type_t type, identification_t *id, bool crl, bool ocsp)
+{
+	trusted_enumerator_t *enumerator = malloc_thing(trusted_enumerator_t);
+	
+	enumerator->public.enumerate = (void*)trusted_enumerate;
+	enumerator->public.destroy = (void*)trusted_destroy;
+	
+	enumerator->candidates = NULL;
+	enumerator->this = this;
+	enumerator->type = type;
+	enumerator->id = id;
+	enumerator->crl = crl;
+	enumerator->ocsp = ocsp;
+	enumerator->pretrusted = NULL;
+	enumerator->auth = NULL;
+	
+	return &enumerator->public;
+}
+
+/**
+ * enumerator for public keys
+ */
+typedef struct {
+	/** implements enumerator_t interface */
+	enumerator_t public;
+	/** enumerator over candidate peer certificates */
+	enumerator_t *inner;
+	/** reference to the credential_manager */
+	private_credential_manager_t *this;
+	/** currently enumerating key */
+	public_key_t *current;
+	/** credset wrapper around auth */
+	auth_info_wrapper_t *wrapper;
+} public_enumerator_t;
+
+/**
+ * Implements public_enumerator_t.enumerate
+ */
+static bool public_enumerate(public_enumerator_t *this,
+							 public_key_t **key, auth_info_t **auth)
+{
+	certificate_t *cert;
+	
+	while (this->inner->enumerate(this->inner, &cert, auth))
+	{
+		DESTROY_IF(this->current);
+		this->current = cert->get_public_key(cert);
+		if (this->current)
+		{
+			*key = this->current;
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+/**
+ * Implements public_enumerator_t.destroy
+ */
+static void public_destroy(public_enumerator_t *this)
+{
+	DESTROY_IF(this->current);
+	this->inner->destroy(this->inner);
+	if (this->wrapper)
+	{
+		remove_local_set(this->this, &this->wrapper->set);
+		this->wrapper->destroy(this->wrapper);
+	}
+	pthread_rwlock_unlock(&this->this->lock);
+	free(this);
+}
+
+/**
+ * Implementation of credential_manager_t.create_public_enumerator.
+ */
+static enumerator_t* create_public_enumerator(private_credential_manager_t *this,
+						key_type_t type, identification_t *id, auth_info_t *auth)
+{
+	public_enumerator_t *enumerator = malloc_thing(public_enumerator_t);
+	
+	enumerator->public.enumerate = (void*)public_enumerate;
+	enumerator->public.destroy = (void*)public_destroy;
+	enumerator->inner = create_trusted_enumerator(this, type, id, TRUE, TRUE);
+	enumerator->this = this;
+	enumerator->current = NULL;
+	enumerator->wrapper = NULL;
+	if (auth)
+	{
+		enumerator->wrapper = auth_info_wrapper_create(auth);
+		add_local_set(this, &enumerator->wrapper->set);
+	}
+	pthread_rwlock_rdlock(&this->lock);
+	return &enumerator->public;
+}
+
+/**
+ * Check if a certificate's keyid is contained in the auth helper
+ */
+static bool auth_contains_cacert(auth_info_t *auth, certificate_t *cert)
+{
+	enumerator_t *enumerator;
+	identification_t *value;
+	auth_item_t type;
+	bool found = FALSE;
+
+	enumerator = auth->create_item_enumerator(auth);
+	while (enumerator->enumerate(enumerator, &type, &value))
+	{
+		if (type == AUTHN_CA_CERT && cert->equals(cert, (certificate_t*)value))
+		{
+			found = TRUE;
+			break;
+		}
+		if (type == AUTHN_CA_CERT_KEYID)
+		{
+			public_key_t *public;
+			identification_t *certid, *keyid;
+			
+			public = cert->get_public_key(cert);
+			if (public)
+			{
+				keyid = (identification_t*)value;
+				certid = public->get_id(public, keyid->get_type(keyid));
+				if (certid && certid->equals(certid, keyid))
+				{
+					public->destroy(public);
+					found = TRUE;
+					break;
+				}
+				public->destroy(public);
+			}
+		}
+	}
+	enumerator->destroy(enumerator);
+	return found;
+}
+
+/**
+ * build a trustchain from subject up to a trust anchor in trusted
+ */
+static auth_info_t *build_trustchain(private_credential_manager_t *this,
+									 certificate_t *subject, auth_info_t *auth)
+{	
+	certificate_t *issuer, *current;
+	auth_info_t *trustchain;
+	u_int level = 0;
+	
+	trustchain = auth_info_create();
+	
+	if (!auth->get_item(auth, AUTHN_CA_CERT, (void**)&current))
+	{
+		/* no trust anchor specified, return this cert only */
+		trustchain->add_item(trustchain, AUTHZ_SUBJECT_CERT, subject);
+		return trustchain;
+	}
+	current = subject->get_ref(subject);
+	while (TRUE)
+	{
+		if (auth_contains_cacert(auth, current))
+		{
+			trustchain->add_item(trustchain, AUTHZ_CA_CERT, current);
+			current->destroy(current);
+			return trustchain;
+		}
+		if (subject == current)
+		{
+			trustchain->add_item(trustchain, AUTHZ_SUBJECT_CERT, current);
+		}
+		else
+		{
+			trustchain->add_item(trustchain, AUTHZ_IM_CERT, current);
+		}
+		issuer = get_issuer_cert(this, current, FALSE);
+		if (!issuer || issuer->equals(issuer, current) || level > MAX_CA_LEVELS)
+		{
+			DESTROY_IF(issuer);
+			current->destroy(current);
+			break;
+		}
+		current->destroy(current);
+		current = issuer;
+		level++;
+	}
+	trustchain->destroy(trustchain);
+	return NULL;
+}
+
+/**
+ * find a private key of a give certificate
+ */
+static private_key_t *get_private_by_cert(private_credential_manager_t *this,
+										  certificate_t *cert, key_type_t type)
+{
+	private_key_t *private = NULL;
+	identification_t* keyid;
+	public_key_t *public;
+
+	public = cert->get_public_key(cert);
+	if (public)
+	{
+		keyid = public->get_id(public, ID_PUBKEY_INFO_SHA1);
+		if (keyid)
+		{
+			private = get_private_by_keyid(this, type, keyid);
+		}
+		public->destroy(public);
+	}
+	return private;
+}
+
+/**
+ * Implementation of credential_manager_t.get_private.
+ */
+static private_key_t *get_private(private_credential_manager_t *this,
+								  key_type_t type, identification_t *id,
+								  auth_info_t *auth)
+{
+	enumerator_t *enumerator;
+	certificate_t *cert;
+	private_key_t *private = NULL;
+	auth_info_t *trustchain;
+	
+	/* check if this is a lookup by key ID, and do it if so */
+	if (id)
+	{
+		switch (id->get_type(id))
+		{
+			case ID_PUBKEY_SHA1:
+			case ID_PUBKEY_INFO_SHA1:
+			case ID_KEY_ID:
+				return get_private_by_keyid(this, type, id);
+			default:
+				break;
+		}
+	}
+	
+	/* try to build a trustchain for each certificate found */
+	enumerator = create_cert_enumerator(this, CERT_ANY, type, id, FALSE);
+	while (enumerator->enumerate(enumerator, &cert))
+	{
+		private = get_private_by_cert(this, cert, type);
+		if (private)
+		{
+			trustchain = build_trustchain(this, cert, auth);
+			if (trustchain)
+			{
+				auth->merge(auth, trustchain);
+				trustchain->destroy(trustchain);
+				break;
+			}
+			private->destroy(private);
+			private = NULL;
+		}
+	}
+	enumerator->destroy(enumerator);
+	/* if no valid trustchain was found, fall back to the first usable cert */
+	if (!private)
+	{
+		enumerator = create_cert_enumerator(this, CERT_ANY, type, id, FALSE);
+		while (enumerator->enumerate(enumerator, &cert))
+		{
+			private = get_private_by_cert(this, cert, type);
+			if (private)
+			{
+				auth->add_item(auth, AUTHZ_SUBJECT_CERT, cert);
+				break;
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+	return private;
+}
+
+/**
+ * Implementation of credential_manager_t.flush_cache.
+ */
+static void flush_cache(private_credential_manager_t *this,
+						certificate_type_t type)
+{
+	this->cache->flush(this->cache, type);
+}
+
+/**
+ * Implementation of credential_manager_t.add_set.
+ */
+static void add_set(private_credential_manager_t *this,
+							   credential_set_t *set)
+{
+	pthread_rwlock_wrlock(&this->lock);
+	this->sets->insert_last(this->sets, set);
+	pthread_rwlock_unlock(&this->lock);
+}
+
+/**
+ * Implementation of credential_manager_t.remove_set.
+ */
+static void remove_set(private_credential_manager_t *this, credential_set_t *set)
+{
+	pthread_rwlock_wrlock(&this->lock);
+	this->sets->remove(this->sets, set, NULL);
+	pthread_rwlock_unlock(&this->lock);
+}
+
+/**
+ * Implementation of credential_manager_t.destroy
+ */
+static void destroy(private_credential_manager_t *this)
+{
+	this->sets->remove(this->sets, this->cache, NULL);
+	this->sets->destroy(this->sets);
+	pthread_key_delete(this->local_sets);
+	this->cache->destroy(this->cache);
+	pthread_rwlock_destroy(&this->lock);
+	free(this);
+}
+
+/*
+ * see header file
+ */
+credential_manager_t *credential_manager_create()
+{
+	private_credential_manager_t *this = malloc_thing(private_credential_manager_t);
+	
+	this->public.create_cert_enumerator = (enumerator_t *(*)(credential_manager_t *this,certificate_type_t cert, key_type_t key,identification_t *id,bool))create_cert_enumerator;
+	this->public.create_shared_enumerator = (enumerator_t *(*)(credential_manager_t *this, shared_key_type_t type,identification_t *me, identification_t *other))create_shared_enumerator;
+	this->public.create_cdp_enumerator = (enumerator_t *(*)(credential_manager_t*, certificate_type_t type, identification_t *id))create_cdp_enumerator;
+	this->public.get_cert = (certificate_t *(*)(credential_manager_t *this,certificate_type_t cert, key_type_t key,identification_t *, bool))get_cert;
+	this->public.get_shared = (shared_key_t *(*)(credential_manager_t *this,shared_key_type_t type,identification_t *me, identification_t *other))get_shared;
+	this->public.get_private = (private_key_t*(*)(credential_manager_t*, key_type_t type, identification_t *, auth_info_t*))get_private;
+	this->public.create_public_enumerator = (enumerator_t*(*)(credential_manager_t*, key_type_t type, identification_t *id, auth_info_t *aut))create_public_enumerator;
+	this->public.flush_cache = (void(*)(credential_manager_t*, certificate_type_t type))flush_cache;
+	this->public.cache_cert = (void(*)(credential_manager_t*, certificate_t *cert))cache_cert;
+	this->public.add_set = (void(*)(credential_manager_t*, credential_set_t *set))add_set;
+	this->public.remove_set = (void(*)(credential_manager_t*, credential_set_t *set))remove_set;
+	this->public.destroy = (void(*)(credential_manager_t*))destroy;
+	
+	this->sets = linked_list_create();
+	pthread_key_create(&this->local_sets, (void*)this->sets->destroy);
+	this->cache = cert_cache_create();
+	this->sets->insert_first(this->sets, this->cache);
+	pthread_rwlock_init(&this->lock, NULL);
+	
+	return &this->public;
+}
+