path: root/src/libstrongswan/plugins/x509/x509_cert.c

/*
 * Copyright (C) 2000 Andreas Hess, Patric Lichtsteiner, Roger Wegmann
 * Copyright (C) 2001 Marco Bertossa, Andreas Schleiss
 * Copyright (C) 2002 Mario Strasser
 * Copyright (C) 2000-2006 Andreas Steffen
 * Copyright (C) 2006-2008 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.
 *
 * $Id$
 */

#define _GNU_SOURCE

#include "x509_cert.h"

#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>

#include <crypto/hashers/hasher.h>
#include <library.h>
#include <debug.h>
#include <asn1/oid.h>
#include <asn1/asn1.h>
#include <asn1/pem.h>
#include <utils/linked_list.h>
#include <utils/identification.h>

/**
 * Different kinds of generalNames
 */
typedef enum {
	GN_OTHER_NAME =		0,
	GN_RFC822_NAME =	1,
	GN_DNS_NAME =		2,
	GN_X400_ADDRESS =	3,
	GN_DIRECTORY_NAME =	4,
	GN_EDI_PARTY_NAME = 5,
	GN_URI =			6,
	GN_IP_ADDRESS =		7,
	GN_REGISTERED_ID =	8,
} generalNames_t;


typedef struct private_x509_cert_t private_x509_cert_t;

/**
 * Private data of a x509_cert_t object.
 */
struct private_x509_cert_t {
	/**
	 * Public interface for this certificate.
	 */
	x509_cert_t public;

	/**
	 * X.509 certificate encoding in ASN.1 DER format
	 */
	chunk_t encoding;

	/**
	 * X.509 certificate body over which signature is computed
	 */
	chunk_t tbsCertificate;

	/**
	 * Version of the X.509 certificate
	 */
	u_int version;
	
	/**
	 * Serial number of the X.509 certificate
	 */
	chunk_t serialNumber;
	
	/**
	 * ID representing the certificate issuer
	 */
	identification_t *issuer;

	/**
	 * Start time of certificate validity
	 */
	time_t notBefore;

	/**
	 * End time of certificate validity
	 */
	time_t notAfter;

	/**
	 * ID representing the certificate subject
	 */
	identification_t *subject;
	
	/**
	 * List of subjectAltNames as identification_t
	 */
	linked_list_t *subjectAltNames;
	
	/**
	 * List of crlDistributionPoints as allocated char*
	 */
	linked_list_t *crl_uris;

	/**
	 * List ocspAccessLocations as identification_t
	 */
	linked_list_t *ocsp_uris;

	/**
	 * certificates embedded public key
	 */
	public_key_t *public_key;
	
	/**
	 * Subject Key Identifier
	 */
	chunk_t subjectKeyID;

	/**
	 * Authority Key Identifier
	 */
	identification_t *authKeyIdentifier;

	/**
	 * Authority Key Serial Number
	 */
	chunk_t authKeySerialNumber;
	
	/**
	 * x509 constraints and other flags
	 */
	x509_flag_t flags;

	/**
	 * Signature algorithm
	 */
	int algorithm;

	/**
	 * Signature
	 */
	chunk_t signature;
	
	/**
	 * reference count
	 */
	refcount_t ref;
};

/**
 * ASN.1 definition of generalName 
 */
static const asn1Object_t generalNameObjects[] = {
	{ 0,   "otherName",		ASN1_CONTEXT_C_0,  ASN1_OPT|ASN1_BODY	}, /*  0 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END				}, /*  1 */
	{ 0,   "rfc822Name",	ASN1_CONTEXT_S_1,  ASN1_OPT|ASN1_BODY	}, /*  2 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END 			}, /*  3 */
	{ 0,   "dnsName",		ASN1_CONTEXT_S_2,  ASN1_OPT|ASN1_BODY	}, /*  4 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END				}, /*  5 */
	{ 0,   "x400Address",	ASN1_CONTEXT_S_3,  ASN1_OPT|ASN1_BODY	}, /*  6 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END				}, /*  7 */
	{ 0,   "directoryName",	ASN1_CONTEXT_C_4,  ASN1_OPT|ASN1_BODY	}, /*  8 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END				}, /*  9 */
	{ 0,   "ediPartyName",	ASN1_CONTEXT_C_5,  ASN1_OPT|ASN1_BODY	}, /* 10 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END				}, /* 11 */
	{ 0,   "URI",			ASN1_CONTEXT_S_6,  ASN1_OPT|ASN1_BODY	}, /* 12 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END				}, /* 13 */
	{ 0,   "ipAddress",		ASN1_CONTEXT_S_7,  ASN1_OPT|ASN1_BODY	}, /* 14 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END				}, /* 15 */
	{ 0,   "registeredID",	ASN1_CONTEXT_S_8,  ASN1_OPT|ASN1_BODY	}, /* 16 */
	{ 0,   "end choice",	ASN1_EOC,          ASN1_END				}  /* 17 */
};

#define GN_OBJ_OTHER_NAME	 	 0
#define GN_OBJ_RFC822_NAME	 	 2
#define GN_OBJ_DNS_NAME		 	 4
#define GN_OBJ_X400_ADDRESS	 	 6
#define GN_OBJ_DIRECTORY_NAME	 8
#define GN_OBJ_EDI_PARTY_NAME	10
#define GN_OBJ_URI				12
#define GN_OBJ_IP_ADDRESS		14
#define GN_OBJ_REGISTERED_ID	16
#define GN_OBJ_ROOF				18

/**
 * ASN.1 definition of otherName 
 */
static const asn1Object_t otherNameObjects[] = {
	{0, "type-id",	ASN1_OID,			ASN1_BODY	}, /*  0 */
	{0, "value",	ASN1_CONTEXT_C_0,	ASN1_BODY	}  /*  1 */
};

#define ON_OBJ_ID_TYPE		0
#define ON_OBJ_VALUE		1
#define ON_OBJ_ROOF			2

/**
 * ASN.1 definition of a basicConstraints extension 
 */
static const asn1Object_t basicConstraintsObjects[] = {
	{ 0, "basicConstraints",	ASN1_SEQUENCE,	ASN1_NONE			}, /*  0 */
	{ 1,   "CA",				ASN1_BOOLEAN,	ASN1_DEF|ASN1_BODY	}, /*  1 */
	{ 1,   "pathLenConstraint",	ASN1_INTEGER,	ASN1_OPT|ASN1_BODY	}, /*  2 */
	{ 1,   "end opt",			ASN1_EOC,		ASN1_END  			}  /*  3 */
};

#define BASIC_CONSTRAINTS_CA	1
#define BASIC_CONSTRAINTS_ROOF	4

/** 
 * ASN.1 definition of a keyIdentifier 
 */
static const asn1Object_t keyIdentifierObjects[] = {
	{ 0,   "keyIdentifier",	ASN1_OCTET_STRING,	ASN1_BODY }  /*  0 */
};

/**
 * ASN.1 definition of a authorityKeyIdentifier extension 
 */
static const asn1Object_t authorityKeyIdentifierObjects[] = {
	{ 0,   "authorityKeyIdentifier",	ASN1_SEQUENCE,		ASN1_NONE 			}, /*  0 */
	{ 1,     "keyIdentifier",			ASN1_CONTEXT_S_0,	ASN1_OPT|ASN1_OBJ	}, /*  1 */
	{ 1,     "end opt",					ASN1_EOC,			ASN1_END  			}, /*  2 */
	{ 1,     "authorityCertIssuer",		ASN1_CONTEXT_C_1,	ASN1_OPT|ASN1_OBJ	}, /*  3 */
	{ 1,     "end opt",					ASN1_EOC,			ASN1_END  			}, /*  4 */
	{ 1,     "authorityCertSerialNumber",ASN1_CONTEXT_S_2,  ASN1_OPT|ASN1_BODY	}, /*  5 */
	{ 1,     "end opt",					ASN1_EOC,			ASN1_END  			}  /*  6 */
};

#define AUTH_KEY_ID_KEY_ID			1
#define AUTH_KEY_ID_CERT_ISSUER		3
#define AUTH_KEY_ID_CERT_SERIAL		5
#define AUTH_KEY_ID_ROOF			7

/**
 * ASN.1 definition of a authorityInfoAccess extension 
 */
static const asn1Object_t authorityInfoAccessObjects[] = {
	{ 0,   "authorityInfoAccess",	ASN1_SEQUENCE,	ASN1_LOOP }, /*  0 */
	{ 1,     "accessDescription",	ASN1_SEQUENCE,	ASN1_NONE }, /*  1 */
	{ 2,       "accessMethod",		ASN1_OID,		ASN1_BODY }, /*  2 */
	{ 2,       "accessLocation",	ASN1_EOC,		ASN1_RAW  }, /*  3 */
	{ 0,   "end loop",				ASN1_EOC,		ASN1_END  }  /*  4 */
};

#define AUTH_INFO_ACCESS_METHOD		2
#define AUTH_INFO_ACCESS_LOCATION	3
#define AUTH_INFO_ACCESS_ROOF		5

/**
 * ASN.1 definition of a extendedKeyUsage extension
 */
static const asn1Object_t extendedKeyUsageObjects[] = {
	{ 0, "extendedKeyUsage",	ASN1_SEQUENCE,	ASN1_LOOP }, /*  0 */
	{ 1,   "keyPurposeID",		ASN1_OID,		ASN1_BODY }, /*  1 */
	{ 0, "end loop",			ASN1_EOC,		ASN1_END  }, /*  2 */
};

#define EXT_KEY_USAGE_PURPOSE_ID	1
#define EXT_KEY_USAGE_ROOF			3

/**
 * ASN.1 definition of generalNames 
 */
static const asn1Object_t generalNamesObjects[] = {
	{ 0, "generalNames",	ASN1_SEQUENCE,	ASN1_LOOP }, /*  0 */
	{ 1,   "generalName",	ASN1_EOC,		ASN1_RAW  }, /*  1 */
	{ 0, "end loop",		ASN1_EOC,		ASN1_END  }  /*  2 */
};

#define GENERAL_NAMES_GN	1
#define GENERAL_NAMES_ROOF	3


/**
 * ASN.1 definition of crlDistributionPoints
 */
static const asn1Object_t crlDistributionPointsObjects[] = {
	{ 0, "crlDistributionPoints",	ASN1_SEQUENCE,		ASN1_LOOP			}, /*  0 */
	{ 1,   "DistributionPoint",		ASN1_SEQUENCE,		ASN1_NONE			}, /*  1 */
	{ 2,     "distributionPoint",	ASN1_CONTEXT_C_0,	ASN1_OPT|ASN1_LOOP	}, /*  2 */
	{ 3,       "fullName",			ASN1_CONTEXT_C_0,	ASN1_OPT|ASN1_OBJ	}, /*  3 */
	{ 3,       "end choice",		ASN1_EOC,			ASN1_END			}, /*  4 */
	{ 3,       "nameRelToCRLIssuer",ASN1_CONTEXT_C_1,	ASN1_OPT|ASN1_BODY	}, /*  5 */
	{ 3,       "end choice",		ASN1_EOC,			ASN1_END			}, /*  6 */
	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /*  7 */
	{ 2,     "reasons",				ASN1_CONTEXT_C_1,	ASN1_OPT|ASN1_BODY	}, /*  8 */
	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /*  9 */
	{ 2,     "crlIssuer",			ASN1_CONTEXT_C_2,	ASN1_OPT|ASN1_BODY	}, /* 10 */
	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /* 11 */
	{ 0, "end loop",				ASN1_EOC,			ASN1_END			}, /* 12 */
};

#define CRL_DIST_POINTS_FULLNAME	 3
#define CRL_DIST_POINTS_ROOF		13

/**
 * ASN.1 definition of an X.509v3 x509_cert
 */
static const asn1Object_t certObjects[] = {
	{ 0, "x509",					ASN1_SEQUENCE,		ASN1_OBJ			}, /*  0 */
	{ 1,   "tbsCertificate",		ASN1_SEQUENCE,		ASN1_OBJ			}, /*  1 */
	{ 2,     "DEFAULT v1",			ASN1_CONTEXT_C_0,	ASN1_DEF			}, /*  2 */
	{ 3,       "version",			ASN1_INTEGER,		ASN1_BODY			}, /*  3 */
	{ 2,     "serialNumber",		ASN1_INTEGER,		ASN1_BODY			}, /*  4 */
	{ 2,     "signature",			ASN1_EOC,			ASN1_RAW			}, /*  5 */
	{ 2,     "issuer",				ASN1_SEQUENCE,		ASN1_OBJ			}, /*  6 */
	{ 2,     "validity",			ASN1_SEQUENCE,		ASN1_NONE			}, /*  7 */
	{ 3,       "notBefore",			ASN1_EOC,			ASN1_RAW			}, /*  8 */
	{ 3,       "notAfter",			ASN1_EOC,			ASN1_RAW			}, /*  9 */
	{ 2,     "subject",				ASN1_SEQUENCE,		ASN1_OBJ			}, /* 10 */
	{ 2,     "subjectPublicKeyInfo",ASN1_SEQUENCE,		ASN1_NONE			}, /* 11 */
	{ 3,       "algorithm",			ASN1_EOC,			ASN1_RAW			}, /* 12 */
	{ 3,       "subjectPublicKey",	ASN1_BIT_STRING,	ASN1_NONE			}, /* 13 */
	{ 4,         "RSAPublicKey",	ASN1_SEQUENCE,		ASN1_RAW			}, /* 14 */
	{ 2,     "issuerUniqueID",		ASN1_CONTEXT_C_1,	ASN1_OPT			}, /* 15 */
	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /* 16 */
	{ 2,     "subjectUniqueID",		ASN1_CONTEXT_C_2,	ASN1_OPT			}, /* 17 */
	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /* 18 */
	{ 2,     "optional extensions",	ASN1_CONTEXT_C_3,	ASN1_OPT			}, /* 19 */
	{ 3,       "extensions",		ASN1_SEQUENCE,		ASN1_LOOP			}, /* 20 */
	{ 4,         "extension",		ASN1_SEQUENCE,		ASN1_NONE			}, /* 21 */
	{ 5,           "extnID",		ASN1_OID,			ASN1_BODY			}, /* 22 */
	{ 5,           "critical",		ASN1_BOOLEAN,		ASN1_DEF|ASN1_BODY	}, /* 23 */
	{ 5,           "extnValue",		ASN1_OCTET_STRING,	ASN1_BODY			}, /* 24 */
	{ 3,       "end loop",			ASN1_EOC,			ASN1_END			}, /* 25 */
	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /* 26 */
	{ 1,   "signatureAlgorithm",	ASN1_EOC,			ASN1_RAW			}, /* 27 */
	{ 1,   "signatureValue",		ASN1_BIT_STRING,	ASN1_BODY			}  /* 28 */
};

#define X509_OBJ_TBS_CERTIFICATE				 1
#define X509_OBJ_VERSION						 3
#define X509_OBJ_SERIAL_NUMBER					 4
#define X509_OBJ_SIG_ALG						 5
#define X509_OBJ_ISSUER 						 6
#define X509_OBJ_NOT_BEFORE						 8
#define X509_OBJ_NOT_AFTER						 9
#define X509_OBJ_SUBJECT						10
#define X509_OBJ_SUBJECT_PUBLIC_KEY_ALGORITHM	12
#define X509_OBJ_SUBJECT_PUBLIC_KEY				13
#define X509_OBJ_RSA_PUBLIC_KEY					14
#define X509_OBJ_EXTN_ID						22
#define X509_OBJ_CRITICAL						23
#define X509_OBJ_EXTN_VALUE						24
#define X509_OBJ_ALGORITHM						27
#define X509_OBJ_SIGNATURE						28
#define X509_OBJ_ROOF							29


static u_char ASN1_sAN_oid_buf[] = {
	0x06, 0x03, 0x55, 0x1D, 0x11
};
static const chunk_t ASN1_subjectAltName_oid = chunk_from_buf(ASN1_sAN_oid_buf);

/**
 * extracts the basicConstraints extension
 */
static bool parse_basicConstraints(chunk_t blob, int level0)
{
	asn1_ctx_t ctx;
	chunk_t object;
	u_int level;
	int objectID = 0;
	bool isCA = FALSE;

	asn1_init(&ctx, blob, level0, FALSE, FALSE);
	while (objectID < BASIC_CONSTRAINTS_ROOF) {

		if (!extract_object(basicConstraintsObjects, &objectID, &object,&level, &ctx))
		{
			break;
		}
		if (objectID == BASIC_CONSTRAINTS_CA)
		{
			isCA = object.len && *object.ptr;
			DBG2("  %s", isCA ? "TRUE" : "FALSE");
		}
		objectID++;
	}
	return isCA;
}

/*
 * extracts an otherName
 */
static bool parse_otherName(chunk_t blob, int level0)
{
	asn1_ctx_t ctx;
	chunk_t object;
	u_int level;
	int objectID = 0;
	int oid = OID_UNKNOWN;

	asn1_init(&ctx, blob, level0, FALSE, FALSE);
	while (objectID < ON_OBJ_ROOF)
	{
		if (!extract_object(otherNameObjects, &objectID, &object, &level, &ctx))
		{
			return FALSE;
		}
		switch (objectID)
		{
			case ON_OBJ_ID_TYPE:
				oid = known_oid(object);
				break;
			case ON_OBJ_VALUE:
				if (oid == OID_XMPP_ADDR)
				{
					if (!parse_asn1_simple_object(&object, ASN1_UTF8STRING,
												  level + 1, "xmppAddr"))
					{
						return FALSE;
					}
				}
				break;
			default:
				break;
		}
		objectID++;
	}
	return TRUE;
}

/*
 * extracts a generalName
 */
static identification_t *parse_generalName(chunk_t blob, int level0)
{
	asn1_ctx_t ctx;
	chunk_t object;
	int objectID = 0;
	u_int level;

	asn1_init(&ctx, blob, level0, FALSE, FALSE);
	while (objectID < GN_OBJ_ROOF)
	{
		id_type_t id_type = ID_ANY;
	
		if (!extract_object(generalNameObjects, &objectID, &object, &level, &ctx))
		{
			return NULL;
		}
		switch (objectID)
		{
			case GN_OBJ_RFC822_NAME:
				id_type = ID_RFC822_ADDR;
				break;
			case GN_OBJ_DNS_NAME:
				id_type = ID_FQDN;
				break;
			case GN_OBJ_URI:
				id_type = ID_DER_ASN1_GN_URI;
				break;
			case GN_OBJ_DIRECTORY_NAME:
				id_type = ID_DER_ASN1_DN;
	    		break;
			case GN_OBJ_IP_ADDRESS:
				id_type = ID_IPV4_ADDR;
				break;
			case GN_OBJ_OTHER_NAME:
				if (!parse_otherName(object, level + 1))
					return NULL;
				break;
			case GN_OBJ_X400_ADDRESS:
			case GN_OBJ_EDI_PARTY_NAME:
			case GN_OBJ_REGISTERED_ID:
				break;
			default:
				break;
		}
		if (id_type != ID_ANY)
		{
			identification_t *gn = identification_create_from_encoding(id_type, object);
			DBG2("  '%D'", gn);
			return gn;
        }
		objectID++;
    }
    return NULL;
}


/**
 * extracts one or several GNs and puts them into a chained list
 */
void x509_parse_generalNames(chunk_t blob, int level0, bool implicit, linked_list_t *list)
{
	asn1_ctx_t ctx;
	chunk_t object;
	u_int level;
	int objectID = 0;

	asn1_init(&ctx, blob, level0, implicit, FALSE);
	while (objectID < GENERAL_NAMES_ROOF)
	{
		if (!extract_object(generalNamesObjects, &objectID, &object, &level, &ctx))
		{
			return;
		}
		if (objectID == GENERAL_NAMES_GN)
		{
			identification_t *gn = parse_generalName(object, level+1);

			if (gn != NULL)
			{
				list->insert_last(list, (void *)gn);
			}
		}
		objectID++;
	}
	return;
}

/**
 * extracts a keyIdentifier
 */
static chunk_t parse_keyIdentifier(chunk_t blob, int level0, bool implicit)
{
	asn1_ctx_t ctx;
	chunk_t object;
	u_int level;
	int objectID = 0;
	
	asn1_init(&ctx, blob, level0, implicit, FALSE);
	if (!extract_object(keyIdentifierObjects, &objectID, &object, &level, &ctx))
	{
		return chunk_empty;
	}
	return object;
}

/**
 * extracts an authoritykeyIdentifier
 */
identification_t* x509_parse_authorityKeyIdentifier(chunk_t blob, int level0,
												chunk_t *authKeySerialNumber)
{
	asn1_ctx_t ctx;
	chunk_t object;
	u_int level;
	int objectID = 0;
	identification_t *authKeyIdentifier = NULL;

	*authKeySerialNumber = chunk_empty;

	asn1_init(&ctx, blob, level0, FALSE, FALSE);
	while (objectID < AUTH_KEY_ID_ROOF)
	{
		if (!extract_object(authorityKeyIdentifierObjects, &objectID, &object, &level, &ctx))
		{
			return NULL;
		}
		switch (objectID) 
		{
			case AUTH_KEY_ID_KEY_ID:
			{
				chunk_t authKeyID = parse_keyIdentifier(object, level+1, TRUE);

				if (authKeyID.ptr == NULL)
				{
					return NULL;
				}
				authKeyIdentifier = identification_create_from_encoding(
											ID_PUBKEY_SHA1, authKeyID); 
				break;
			}
			case AUTH_KEY_ID_CERT_ISSUER:
			{
				/* TODO: x509_parse_generalNames(object, level+1, TRUE); */
				break;
			}
			case AUTH_KEY_ID_CERT_SERIAL:
				*authKeySerialNumber = object;
				break;
			default:
				break;
		}
		objectID++;
	}
	return authKeyIdentifier;
}

/**
 * extracts an authorityInfoAcess location
 */
static void parse_authorityInfoAccess(chunk_t blob, int level0,
									  private_x509_cert_t *this)
{
	asn1_ctx_t ctx;
	chunk_t object;
	u_int level;
	int objectID = 0;
	int accessMethod = OID_UNKNOWN;
	
	asn1_init(&ctx, blob, level0, FALSE, FALSE);
	while (objectID < AUTH_INFO_ACCESS_ROOF)
	{
		if (!extract_object(authorityInfoAccessObjects, &objectID, &object, &level, &ctx))
		{
			return;
		}
		switch (objectID) 
		{
			case AUTH_INFO_ACCESS_METHOD:
				accessMethod = known_oid(object);
				break;
			case AUTH_INFO_ACCESS_LOCATION:
			{
				switch (accessMethod)
				{
					case OID_OCSP:
					case OID_CA_ISSUERS:
						{
							identification_t *id;
							char *uri;

							id = parse_generalName(object, level+1);
							if (id == NULL)
							{	/* parsing went wrong - abort */
								return;
							}
							DBG2("  '%D'", id);
							if (accessMethod == OID_OCSP &&
								asprintf(&uri, "%D", id) > 0)
							{
								this->ocsp_uris->insert_last(this->ocsp_uris, uri);
							}
							id->destroy(id);
						}
						break;
					default:
						/* unkown accessMethod, ignoring */
						break;
				}
				break;
			}
			default:
				break;
		}
		objectID++;
	}
}

/**
 * extracts extendedKeyUsage OIDs
 */
static bool parse_extendedKeyUsage(chunk_t blob, int level0)
{
	asn1_ctx_t ctx;
	chunk_t object;
	u_int level;
	int objectID = 0;
	
	asn1_init(&ctx, blob, level0, FALSE, FALSE);
	while (objectID < EXT_KEY_USAGE_ROOF)
	{
		if (!extract_object(extendedKeyUsageObjects, &objectID, &object, &level, &ctx))
		{
			return FALSE;
		}
		if (objectID == EXT_KEY_USAGE_PURPOSE_ID && 
			known_oid(object) == OID_OCSP_SIGNING)
		{
			return TRUE;
		}
		objectID++;
	}
	return FALSE;
}

/**
 * extracts one or several crlDistributionPoints into a list
 */
static void parse_crlDistributionPoints(chunk_t blob, int level0,
										private_x509_cert_t *this)
{
	asn1_ctx_t ctx;
	chunk_t object;
	u_int level;
	int objectID = 0;
	linked_list_t *list;
	identification_t *id;
	char *uri;
	
	list = linked_list_create();
	asn1_init(&ctx, blob, level0, FALSE, FALSE);
	while (objectID < CRL_DIST_POINTS_ROOF)
	{
		if (!extract_object(crlDistributionPointsObjects, &objectID, &object, &level, &ctx))
		{
			list->destroy_offset(list, offsetof(identification_t, destroy));
			return;
		}
		if (objectID == CRL_DIST_POINTS_FULLNAME)
		{	/* append extracted generalNames to existing chained list */
			x509_parse_generalNames(object, level+1, TRUE, list);
	
			while (list->remove_last(list, (void**)&id) == SUCCESS)
			{
				if (asprintf(&uri, "%D", id) > 0)
				{
					this->crl_uris->insert_last(this->crl_uris, uri);
				}
				id->destroy(id);
			}
		}
		objectID++;
	}
	list->destroy(list);
}

/**
 * Parses an X.509v3 certificate
 */
static bool parse_certificate(private_x509_cert_t *this)
{
	asn1_ctx_t ctx;
	bool critical;
	chunk_t object;
	u_int level;
	int objectID = 0;
	int extn_oid = OID_UNKNOWN;
	int key_alg = OID_UNKNOWN;
	int sig_alg = OID_UNKNOWN;
	chunk_t subjectPublicKey = chunk_empty;
	
	asn1_init(&ctx, this->encoding, 0, FALSE, FALSE);
	while (objectID < X509_OBJ_ROOF)
	{
		if (!extract_object(certObjects, &objectID, &object, &level, &ctx))
		{
			return FALSE;
		}
		/* those objects which will parsed further need the next higher level */
		level++;
		switch (objectID)
		{
			case X509_OBJ_TBS_CERTIFICATE:
				this->tbsCertificate = object;
				break;
			case X509_OBJ_VERSION:
				this->version = (object.len) ? (1+(u_int)*object.ptr) : 1;
				DBG2("  v%d", this->version);
				break;
			case X509_OBJ_SERIAL_NUMBER:
				this->serialNumber = object;
				break;
			case X509_OBJ_SIG_ALG:
				sig_alg = parse_algorithmIdentifier(object, level, NULL);
				break;
			case X509_OBJ_ISSUER:
				this->issuer = identification_create_from_encoding(ID_DER_ASN1_DN, object);
				DBG2("  '%D'", this->issuer);
				break;
			case X509_OBJ_NOT_BEFORE:
				this->notBefore = parse_time(object, level);
				break;
			case X509_OBJ_NOT_AFTER:
				this->notAfter = parse_time(object, level);
				break;
			case X509_OBJ_SUBJECT:
				this->subject = identification_create_from_encoding(ID_DER_ASN1_DN, object);
				DBG2("  '%D'", this->subject);
				break;
			case X509_OBJ_SUBJECT_PUBLIC_KEY_ALGORITHM:
				key_alg = parse_algorithmIdentifier(object, level, NULL);
				break;
			case X509_OBJ_SUBJECT_PUBLIC_KEY:
				if (ctx.blobs[4].len > 0 && *ctx.blobs[4].ptr == 0x00)
				{
					/* skip initial bit string octet defining 0 unused bits */
					ctx.blobs[4].ptr++; ctx.blobs[4].len--;
				}
				break;
			case X509_OBJ_RSA_PUBLIC_KEY:
				subjectPublicKey = object;
				switch (key_alg)
				{
					case OID_RSA_ENCRYPTION:
						this->public_key = lib->creds->create(lib->creds,
							CRED_PUBLIC_KEY, KEY_RSA,
							BUILD_BLOB_ASN1_DER, chunk_clone(subjectPublicKey),
							BUILD_END);
						break;
					default:
						DBG1("parsing key type %d failed", key_alg);
						return FALSE;
				}
				break;
			case X509_OBJ_EXTN_ID:
				extn_oid = known_oid(object);
				break;
			case X509_OBJ_CRITICAL:
				critical = object.len && *object.ptr;
				DBG2("  %s", critical ? "TRUE" : "FALSE");
				break;
			case X509_OBJ_EXTN_VALUE:
			{
				switch (extn_oid)
				{
					case OID_SUBJECT_KEY_ID:
						this->subjectKeyID = parse_keyIdentifier(object, level, FALSE);
						break;
					case OID_SUBJECT_ALT_NAME:
						x509_parse_generalNames(object, level, FALSE, this->subjectAltNames);
						break;
					case OID_BASIC_CONSTRAINTS:
						if (parse_basicConstraints(object, level))
						{
							this->flags |= X509_CA;
						}
						break;
					case OID_CRL_DISTRIBUTION_POINTS:
						parse_crlDistributionPoints(object, level, this);
						break;
					case OID_AUTHORITY_KEY_ID:
						this->authKeyIdentifier = x509_parse_authorityKeyIdentifier(object,
							 							level, &this->authKeySerialNumber);
						break;
					case OID_AUTHORITY_INFO_ACCESS:
						parse_authorityInfoAccess(object, level, this);
						break;
					case OID_EXTENDED_KEY_USAGE:
						if (parse_extendedKeyUsage(object, level))
						{
							this->flags |= X509_OCSP_SIGNER;
						}
						break;
					case OID_NS_REVOCATION_URL:
					case OID_NS_CA_REVOCATION_URL:
					case OID_NS_CA_POLICY_URL:
					case OID_NS_COMMENT:
						if (!parse_asn1_simple_object(&object, ASN1_IA5STRING, 
											level, oid_names[extn_oid].name))
							return FALSE;
						break;
					default:
						break;
				}
				break;
			}
			case X509_OBJ_ALGORITHM:
				this->algorithm = parse_algorithmIdentifier(object, level, NULL);
				if (this->algorithm != sig_alg)
				{
					DBG1("  signature algorithms do not agree");
					return FALSE;
				}
				break;
			case X509_OBJ_SIGNATURE:
				this->signature = object;
				break;
			default:
				break;
		}
		objectID++;
	}
	return TRUE;
}

/**
 * Implementation of certificate_t.get_type
 */
static certificate_type_t get_type(private_x509_cert_t *this)
{
	return CERT_X509;
}

/**
 * Implementation of certificate_t.get_subject
 */
static identification_t* get_subject(private_x509_cert_t *this)
{
	return this->subject;
}

/**
 * Implementation of certificate_t.get_issuer
 */
static identification_t* get_issuer(private_x509_cert_t *this)
{
	return this->issuer;
}

/**
 * Implementation of certificate_t.has_subject.
 */
static id_match_t has_subject(private_x509_cert_t *this, identification_t *subject)
{
	identification_t *current;
	enumerator_t *enumerator;
	id_match_t match, best;

	best = this->subject->matches(this->subject, subject);
	enumerator = this->subjectAltNames->create_enumerator(this->subjectAltNames);
	while (enumerator->enumerate(enumerator, &current))
	{
		match = current->matches(current, subject);
		if (match > best)
		{
			best = match;	
		}
	}
	enumerator->destroy(enumerator);
	return best;	
}

/**
 * Implementation of certificate_t.has_subject.
 */
static id_match_t has_issuer(private_x509_cert_t *this, identification_t *issuer)
{
	/* issuerAltNames currently not supported */
	return this->issuer->matches(this->issuer, issuer);
}

/**
 * Implementation of certificate_t.issued_by
 */
static bool issued_by(private_x509_cert_t *this, certificate_t *issuer)
{
	public_key_t *key;
	signature_scheme_t scheme;
	bool valid;
	x509_t *x509 = (x509_t*)issuer;
	
	if (&this->public.interface.interface == issuer)
	{
		if (this->flags & X509_SELF_SIGNED)
		{
			return TRUE;
		}
	}
	else
	{
		if (issuer->get_type(issuer) != CERT_X509)
		{
			return FALSE;
		}
		if (!(x509->get_flags(x509) & X509_CA))
		{
			return FALSE;
		}
	}
	if (!this->issuer->equals(this->issuer, issuer->get_subject(issuer)))
	{
		return FALSE;
	}
	/* TODO: generic OID to scheme mapper? */
	switch (this->algorithm)
	{
		case OID_MD5_WITH_RSA:
			scheme = SIGN_RSA_EMSA_PKCS1_MD5;
			break;
		case OID_SHA1_WITH_RSA:
			scheme = SIGN_RSA_EMSA_PKCS1_SHA1;
			break;
		case OID_SHA256_WITH_RSA:
			scheme = SIGN_RSA_EMSA_PKCS1_SHA256;
			break;
		case OID_SHA384_WITH_RSA:
			scheme = SIGN_RSA_EMSA_PKCS1_SHA384;
			break;
		case OID_SHA512_WITH_RSA:
			scheme = SIGN_RSA_EMSA_PKCS1_SHA512;
			break;
		default:
			return FALSE;
	}
	key = issuer->get_public_key(issuer);
	if (key == NULL)
	{
		return FALSE;
	}
	/* TODO: add a lightweight check option (comparing auth/subject keyids only) */
	valid = key->verify(key, scheme, this->tbsCertificate, this->signature);
	key->destroy(key);
	return valid;
}

/**
 * Implementation of certificate_t.get_public_key
 */
static public_key_t* get_public_key(private_x509_cert_t *this)
{
	this->public_key->get_ref(this->public_key);
	return this->public_key;
}

/**
 * Implementation of certificate_t.asdf
 */
static private_x509_cert_t* get_ref(private_x509_cert_t *this)
{
	ref_get(&this->ref);
	return this;
}

/**
 * Implementation of x509_cert_t.get_flags.
 */
static x509_flag_t get_flags(private_x509_cert_t *this)
{
	return this->flags;
}

/**
 * Implementation of x509_cert_t.get_validity.
 */
static bool get_validity(private_x509_cert_t *this, time_t *when,
						 time_t *not_before, time_t *not_after)
{
	time_t t;
	
	if (when)
	{
		t = *when;
	}
	else
	{
		t = time(NULL);
	}
	if (not_before)
	{
		*not_before = this->notBefore;
	}
	if (not_after)
	{
		*not_after = this->notAfter;
	}
	return (t >= this->notBefore && t <= this->notAfter);
}

/**
 * Implementation of certificate_t.is_newer.
 */
static bool is_newer(certificate_t *this, certificate_t *that)
{
	time_t this_update, that_update, now = time(NULL);
	bool new;

	this->get_validity(this, &now, &this_update, NULL);
	that->get_validity(that, &now, &that_update, NULL);
	new = this_update > that_update;
	DBG1("  certificate from %#T is %s - existing certificate from %#T %s",
				&this_update, FALSE, new ? "newer":"not newer",
				&that_update, FALSE, new ? "replaced":"retained");
	return new;
}
	
/**
 * Implementation of certificate_t.get_encoding.
 */
static chunk_t get_encoding(private_x509_cert_t *this)
{
	return chunk_clone(this->encoding);
}

/**
 * Implementation of certificate_t.equals.
 */
static bool equals(private_x509_cert_t *this, certificate_t *other)
{
	chunk_t encoding;
	bool equal;

	if (this == (private_x509_cert_t*)other)
	{
		return TRUE;
	}
	if (other->get_type(other) != CERT_X509)
	{
		return FALSE;
	}
	if (other->equals == (void*)equals)
	{	/* skip allocation if we have the same implementation */
		return chunk_equals(this->encoding, ((private_x509_cert_t*)other)->encoding); 
	}
	encoding = other->get_encoding(other);
	equal = chunk_equals(this->encoding, encoding);
	free(encoding.ptr);
	return equal;
}

/**
 * Implementation of x509_t.get_serial.
 */
static chunk_t get_serial(private_x509_cert_t *this)
{
	return this->serialNumber;
}

/**
 * Implementation of x509_t.get_authKeyIdentifier.
 */
static identification_t *get_authKeyIdentifier(private_x509_cert_t *this)
{
	return this->authKeyIdentifier;
}

/**
 * Implementation of x509_cert_t.create_subjectAltName_enumerator.
 */
static enumerator_t* create_subjectAltName_enumerator(private_x509_cert_t *this)
{
	return this->subjectAltNames->create_enumerator(this->subjectAltNames);
}

/**
 * Implementation of x509_cert_t.create_ocsp_uri_enumerator.
 */
static enumerator_t* create_ocsp_uri_enumerator(private_x509_cert_t *this)
{
	return this->ocsp_uris->create_enumerator(this->ocsp_uris);
}

/**
 * Implementation of x509_cert_t.create_crl_uri_enumerator.
 */
static enumerator_t* create_crl_uri_enumerator(private_x509_cert_t *this)
{
	return this->crl_uris->create_enumerator(this->crl_uris);
}

/**
 * Implementation of certificate_t.asdf
 */
static void destroy(private_x509_cert_t *this)
{
	if (ref_put(&this->ref))
	{
		this->subjectAltNames->destroy_offset(this->subjectAltNames,
									offsetof(identification_t, destroy));
		this->crl_uris->destroy_function(this->crl_uris, free);
		this->ocsp_uris->destroy_function(this->ocsp_uris, free);
		DESTROY_IF(this->issuer);
		DESTROY_IF(this->subject);
		DESTROY_IF(this->public_key);
		DESTROY_IF(this->authKeyIdentifier);
		chunk_free(&this->encoding);
		free(this);
	}
}

/**
 * create an empty but initialized X.509 certificate
 */
static private_x509_cert_t* create_empty(void)
{
	private_x509_cert_t *this = malloc_thing(private_x509_cert_t);
	
	this->public.interface.interface.get_type = (certificate_type_t (*)(certificate_t *this))get_type;
	this->public.interface.interface.get_subject = (identification_t* (*)(certificate_t *this))get_subject;
	this->public.interface.interface.get_issuer = (identification_t* (*)(certificate_t *this))get_issuer;
	this->public.interface.interface.has_subject = (id_match_t (*)(certificate_t*, identification_t *subject))has_subject;
	this->public.interface.interface.has_issuer = (id_match_t (*)(certificate_t*, identification_t *issuer))has_issuer;
	this->public.interface.interface.issued_by = (bool (*)(certificate_t *this, certificate_t *issuer))issued_by;
	this->public.interface.interface.get_public_key = (public_key_t* (*)(certificate_t *this))get_public_key;
	this->public.interface.interface.get_validity = (bool (*)(certificate_t*, time_t *when, time_t *, time_t*))get_validity;
	this->public.interface.interface.is_newer = (bool (*)(certificate_t*,certificate_t*))is_newer;
	this->public.interface.interface.get_encoding = (chunk_t (*)(certificate_t*))get_encoding;
	this->public.interface.interface.equals = (bool (*)(certificate_t*, certificate_t *other))equals;
	this->public.interface.interface.get_ref = (certificate_t* (*)(certificate_t *this))get_ref;
	this->public.interface.interface.destroy = (void (*)(certificate_t *this))destroy;
	this->public.interface.get_flags = (x509_flag_t (*)(x509_t*))get_flags;
	this->public.interface.get_serial = (chunk_t (*)(x509_t*))get_serial;
	this->public.interface.get_authKeyIdentifier = (identification_t* (*)(x509_t*))get_authKeyIdentifier;
	this->public.interface.create_subjectAltName_enumerator = (enumerator_t* (*)(x509_t*))create_subjectAltName_enumerator;
	this->public.interface.create_crl_uri_enumerator = (enumerator_t* (*)(x509_t*))create_crl_uri_enumerator;
	this->public.interface.create_ocsp_uri_enumerator = (enumerator_t* (*)(x509_t*))create_ocsp_uri_enumerator;

	this->encoding = chunk_empty;
	this->public_key = NULL;
	this->subject = NULL;
	this->issuer = NULL;
	this->subjectAltNames = linked_list_create();
	this->crl_uris = linked_list_create();
	this->ocsp_uris = linked_list_create();
	this->subjectKeyID = chunk_empty;
	this->authKeyIdentifier = NULL;
	this->authKeySerialNumber = chunk_empty;
	this->flags = 0;
	this->ref = 1;

	return this;
}

/**
 * create an X.509 certificate from a chunk
 */
static private_x509_cert_t *create_from_chunk(chunk_t chunk)
{
	private_x509_cert_t *this = create_empty();

	this->encoding = chunk;
	if (!parse_certificate(this))
	{
		destroy(this);
		return NULL;
	}

	/* check if the certificate is self-signed */
	if (issued_by(this, &this->public.interface.interface))
	{
		this->flags |= X509_SELF_SIGNED;
	}
	return this;
}

/**
 * create an X.509 certificate from a file
 */
static private_x509_cert_t *create_from_file(char *path)
{
	bool pgp = FALSE;
	chunk_t chunk;
	private_x509_cert_t *this;
	
	if (!pem_asn1_load_file(path, NULL, &chunk, &pgp))
	{
		return NULL;
	}

	this = create_from_chunk(chunk);

	if (this == NULL)
	{
		DBG1("  could not parse loaded certificate file '%s'",path);
		return NULL;
	}
	DBG1("  loaded certificate file '%s'",  path);
	return this;

}

typedef struct private_builder_t private_builder_t;
/**
 * Builder implementation for certificate loading
 */
struct private_builder_t {
	/** implements the builder interface */
	builder_t public;
	/** loaded certificate */
	private_x509_cert_t *cert;
	/** additional flags to enforce */
	x509_flag_t flags;
};

/**
 * Implementation of builder_t.build
 */
static private_x509_cert_t *build(private_builder_t *this)
{
	private_x509_cert_t *cert = this->cert;
	x509_flag_t flags = this->flags;

	free(this);
	if (cert == NULL)
	{
		return NULL;
	}
	if ((flags & X509_CA) && !(cert->flags & X509_CA))
	{
		DBG1("  ca certificate must have ca basic constraint set, discarded");
		destroy(cert);
		return NULL;
	}
	cert->flags |= flags;
	return cert;
}

/**
 * Implementation of builder_t.add
 */
static void add(private_builder_t *this, builder_part_t part, ...)
{
	va_list args;
	
	va_start(args, part);
	switch (part)
	{
		case BUILD_FROM_FILE:
			this->cert = create_from_file(va_arg(args, char*));
			break;
		case BUILD_BLOB_ASN1_DER:
			this->cert = create_from_chunk(va_arg(args, chunk_t));
			break;
		case BUILD_X509_FLAG:
			this->flags = va_arg(args, x509_flag_t);
			break;
		default:
			DBG1("ignoring unsupported build part %N", builder_part_names, part);
			break;
	}
	va_end(args);
}

/**
 * Builder construction function
 */
builder_t *x509_cert_builder(certificate_type_t type)
{
	private_builder_t *this;
	
	if (type != CERT_X509)
	{
		return NULL;
	}
	
	this = malloc_thing(private_builder_t);
	
	this->cert = NULL;
	this->flags = 0;
	this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add;
	this->public.build = (void*(*)(builder_t *this))build;
	
	return &this->public;
}