752 lines
17 KiB
C
752 lines
17 KiB
C
/* Simple ASN.1 parser
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* Copyright (C) 2000-2004 Andreas Steffen, Zuercher Hochschule Winterthur
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* Copyright (C) 2006 Martin Will, 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 <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include "asn1.h"
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#include <utils/logger_manager.h>
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/* Names of the months */
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static const char* months[] = {
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"Jan", "Feb", "Mar", "Apr", "May", "Jun",
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"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
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};
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/* some common prefabricated ASN.1 constants */
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static u_char ASN1_INTEGER_0_str[] = { 0x02, 0x00 };
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static u_char ASN1_INTEGER_1_str[] = { 0x02, 0x01, 0x01 };
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static u_char ASN1_INTEGER_2_str[] = { 0x02, 0x01, 0x02 };
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const chunk_t ASN1_INTEGER_0 = chunk_from_buf(ASN1_INTEGER_0_str);
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const chunk_t ASN1_INTEGER_1 = chunk_from_buf(ASN1_INTEGER_1_str);
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const chunk_t ASN1_INTEGER_2 = chunk_from_buf(ASN1_INTEGER_2_str);
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/* some popular algorithmIdentifiers */
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static u_char ASN1_md5_id_str[] = {
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0x30, 0x0C,
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0x06, 0x08, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05,
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0x05, 0x00
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};
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static u_char ASN1_sha1_id_str[] = {
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0x30, 0x09,
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0x06, 0x05, 0x2B, 0x0E,0x03, 0x02, 0x1A,
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0x05, 0x00
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};
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static u_char ASN1_md5WithRSA_id_str[] = {
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0x30, 0x0D,
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0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x04,
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0x05, 0x00
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};
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static u_char ASN1_sha1WithRSA_id_str[] = {
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0x30, 0x0D,
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0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x05,
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0x05, 0x00
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};
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static u_char ASN1_rsaEncryption_id_str[] = {
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0x30, 0x0D,
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0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01,
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0x05, 0x00
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};
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const chunk_t ASN1_md5_id = chunk_from_buf(ASN1_md5_id_str);
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const chunk_t ASN1_sha1_id = chunk_from_buf(ASN1_sha1_id_str);
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const chunk_t ASN1_rsaEncryption_id = chunk_from_buf(ASN1_rsaEncryption_id_str);
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const chunk_t ASN1_md5WithRSA_id = chunk_from_buf(ASN1_md5WithRSA_id_str);
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const chunk_t ASN1_sha1WithRSA_id = chunk_from_buf(ASN1_sha1WithRSA_id_str);
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/* ASN.1 definiton of an algorithmIdentifier */
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static const asn1Object_t algorithmIdentifierObjects[] = {
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{ 0, "algorithmIdentifier", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
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{ 1, "algorithm", ASN1_OID, ASN1_BODY }, /* 1 */
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{ 1, "parameters", ASN1_EOC, ASN1_RAW } /* 2 */
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};
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#define ALGORITHM_ID_ALG 1
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#define ALGORITHM_ID_PARAMETERS 2
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#define ALGORITHM_ID_ROOF 3
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static logger_t *logger = NULL;
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/**
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* initializes the ASN.1 logger
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*/
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static void asn1_init_logger()
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{
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if (logger == NULL)
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logger = logger_manager->get_logger(logger_manager, ASN1);
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}
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/**
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* return the ASN.1 encoded algorithm identifier
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*/
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chunk_t asn1_algorithmIdentifier(int oid)
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{
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switch (oid)
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{
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case OID_RSA_ENCRYPTION:
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return ASN1_rsaEncryption_id;
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case OID_MD5_WITH_RSA:
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return ASN1_md5WithRSA_id;
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case OID_SHA1_WITH_RSA:
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return ASN1_sha1WithRSA_id;
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case OID_MD5:
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return ASN1_md5_id;
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case OID_SHA1:
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return ASN1_sha1_id;
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default:
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return CHUNK_INITIALIZER;
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}
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}
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/**
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* If the oid is listed in the oid_names table then the corresponding
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* position in the oid_names table is returned otherwise -1 is returned
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*/
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int known_oid(chunk_t object)
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{
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int oid = 0;
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while (object.len)
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{
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if (oid_names[oid].octet == *object.ptr)
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{
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if (--object.len == 0 || oid_names[oid].down == 0)
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{
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return oid; /* found terminal symbol */
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}
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else
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{
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object.ptr++; oid++; /* advance to next hex octet */
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}
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}
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else
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{
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if (oid_names[oid].next)
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oid = oid_names[oid].next;
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else
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return OID_UNKNOWN;
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}
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}
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return -1;
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}
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/**
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* Decodes the length in bytes of an ASN.1 object
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*/
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u_int asn1_length(chunk_t *blob)
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{
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u_char n;
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size_t len;
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/* advance from tag field on to length field */
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blob->ptr++;
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blob->len--;
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/* read first octet of length field */
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n = *blob->ptr++;
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blob->len--;
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if ((n & 0x80) == 0)
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{/* single length octet */
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return n;
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}
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/* composite length, determine number of length octets */
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n &= 0x7f;
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if (n > blob->len)
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{
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logger->log(logger, ERROR|LEVEL1, "number of length octets is larger than ASN.1 object");
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return ASN1_INVALID_LENGTH;
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}
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if (n > sizeof(len))
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{
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logger->log(logger, ERROR|LEVEL1, "number of length octets is larger than limit of %d octets",
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(int)sizeof(len));
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return ASN1_INVALID_LENGTH;
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}
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len = 0;
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while (n-- > 0)
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{
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len = 256*len + *blob->ptr++;
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blob->len--;
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}
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return len;
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}
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/**
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* determines if a character string is of type ASN.1 printableString
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*/
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bool is_printablestring(chunk_t str)
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{
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const char printablestring_charset[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 '()+,-./:=?";
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u_int i;
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for (i = 0; i < str.len; i++)
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{
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if (strchr(printablestring_charset, str.ptr[i]) == NULL)
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return FALSE;
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}
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return TRUE;
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}
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/**
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* Display a date either in local or UTC time
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* TODO: Does not seem to be thread safe
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*/
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char* timetoa(const time_t *time, bool utc)
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{
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static char buf[30];
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if (*time == 0)
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sprintf(buf, "--- -- --:--:--%s----", (utc)?" UTC ":" ");
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else
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{
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struct tm *t = (utc)? gmtime(time) : localtime(time);
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sprintf(buf, "%s %02d %02d:%02d:%02d%s%04d",
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months[t->tm_mon], t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec,
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(utc)?" UTC ":" ", t->tm_year + 1900);
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}
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return buf;
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}
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/**
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* Converts ASN.1 UTCTIME or GENERALIZEDTIME into calender time
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*/
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time_t asn1totime(const chunk_t *utctime, asn1_t type)
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{
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struct tm t;
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time_t tz_offset;
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u_char *eot = NULL;
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if ((eot = memchr(utctime->ptr, 'Z', utctime->len)) != NULL)
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{
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tz_offset = 0; /* Zulu time with a zero time zone offset */
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}
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else if ((eot = memchr(utctime->ptr, '+', utctime->len)) != NULL)
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{
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int tz_hour, tz_min;
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sscanf(eot+1, "%2d%2d", &tz_hour, &tz_min);
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tz_offset = 3600*tz_hour + 60*tz_min; /* positive time zone offset */
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}
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else if ((eot = memchr(utctime->ptr, '-', utctime->len)) != NULL)
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{
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int tz_hour, tz_min;
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sscanf(eot+1, "%2d%2d", &tz_hour, &tz_min);
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tz_offset = -3600*tz_hour - 60*tz_min; /* negative time zone offset */
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}
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else
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{
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return 0; /* error in time format */
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}
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{
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const char* format = (type == ASN1_UTCTIME)? "%2d%2d%2d%2d%2d":
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"%4d%2d%2d%2d%2d";
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sscanf(utctime->ptr, format, &t.tm_year, &t.tm_mon, &t.tm_mday,
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&t.tm_hour, &t.tm_min);
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}
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/* is there a seconds field? */
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if ((eot - utctime->ptr) == ((type == ASN1_UTCTIME)?12:14))
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{
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sscanf(eot-2, "%2d", &t.tm_sec);
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}
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else
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{
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t.tm_sec = 0;
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}
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/* representation of year */
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if (t.tm_year >= 1900)
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{
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t.tm_year -= 1900;
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}
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else if (t.tm_year >= 100)
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{
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return 0;
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}
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else if (t.tm_year < 50)
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{
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t.tm_year += 100;
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}
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/* representation of month 0..11*/
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t.tm_mon--;
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/* set daylight saving time to off */
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t.tm_isdst = 0;
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/* compensate timezone */
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return mktime(&t) - timezone - tz_offset;
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}
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/**
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* Initializes the internal context of the ASN.1 parser
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*/
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void asn1_init(asn1_ctx_t *ctx, chunk_t blob, u_int level0, bool implicit)
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{
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asn1_init_logger();
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ctx->blobs[0] = blob;
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ctx->level0 = level0;
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ctx->implicit = implicit;
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memset(ctx->loopAddr, '\0', sizeof(ctx->loopAddr));
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}
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/**
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* print the value of an ASN.1 simple object
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*/
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static void debug_asn1_simple_object(chunk_t object, asn1_t type)
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{
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int oid;
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time_t time;
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switch (type)
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{
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case ASN1_OID:
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oid = known_oid(object);
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if (oid != OID_UNKNOWN)
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{
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logger->log(logger, CONTROL|LEVEL1, " '%s'", oid_names[oid].name);
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return;
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}
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break;
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case ASN1_UTF8STRING:
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case ASN1_IA5STRING:
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case ASN1_PRINTABLESTRING:
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case ASN1_T61STRING:
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case ASN1_VISIBLESTRING:
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logger->log(logger, CONTROL|LEVEL1, " '%.*s'", (int)object.len, object.ptr);
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return;
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case ASN1_UTCTIME:
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case ASN1_GENERALIZEDTIME:
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time = asn1totime(&object, type);
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logger->log(logger, CONTROL|LEVEL1, " '%s'", timetoa(&time, TRUE));
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return;
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default:
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break;
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}
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logger->log_chunk(logger, RAW|LEVEL1, "", object);
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}
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/**
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* Parses and extracts the next ASN.1 object
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*/
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bool extract_object(asn1Object_t const *objects, u_int *objectID, chunk_t *object, u_int *level, asn1_ctx_t *ctx)
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{
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asn1Object_t obj = objects[*objectID];
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chunk_t *blob;
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chunk_t *blob1;
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u_char *start_ptr;
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*object = CHUNK_INITIALIZER;
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if (obj.flags & ASN1_END) /* end of loop or option found */
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{
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if (ctx->loopAddr[obj.level] && ctx->blobs[obj.level+1].len > 0)
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{
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*objectID = ctx->loopAddr[obj.level]; /* another iteration */
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obj = objects[*objectID];
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}
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else
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{
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ctx->loopAddr[obj.level] = 0; /* exit loop or option*/
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return TRUE;
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}
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}
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*level = ctx->level0 + obj.level;
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blob = ctx->blobs + obj.level;
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blob1 = blob + 1;
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start_ptr = blob->ptr;
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/* handle ASN.1 defaults values */
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if ((obj.flags & ASN1_DEF) && (blob->len == 0 || *start_ptr != obj.type) )
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{
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/* field is missing */
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logger->log(logger, CONTROL|LEVEL1, "L%d - %s:", *level, obj.name);
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if (obj.type & ASN1_CONSTRUCTED)
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{
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(*objectID)++ ; /* skip context-specific tag */
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}
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return TRUE;
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}
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/* handle ASN.1 options */
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if ((obj.flags & ASN1_OPT)
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&& (blob->len == 0 || *start_ptr != obj.type))
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{
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/* advance to end of missing option field */
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do
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(*objectID)++;
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while (!((objects[*objectID].flags & ASN1_END)
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&& (objects[*objectID].level == obj.level)));
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return TRUE;
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}
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/* an ASN.1 object must possess at least a tag and length field */
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if (blob->len < 2)
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{
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logger->log(logger, ERROR|LEVEL1, "L%d - %s: ASN.1 object smaller than 2 octets",
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*level, obj.name);
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return FALSE;
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}
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blob1->len = asn1_length(blob);
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if (blob1->len == ASN1_INVALID_LENGTH || blob->len < blob1->len)
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{
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logger->log(logger, ERROR|LEVEL1, "L%d - %s: length of ASN.1 object invalid or too large",
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*level, obj.name);
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return FALSE;
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}
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blob1->ptr = blob->ptr;
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blob->ptr += blob1->len;
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blob->len -= blob1->len;
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/* return raw ASN.1 object without prior type checking */
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if (obj.flags & ASN1_RAW)
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{
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logger->log(logger, CONTROL|LEVEL1, "L%d - %s:", *level, obj.name);
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object->ptr = start_ptr;
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object->len = (size_t)(blob->ptr - start_ptr);
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return TRUE;
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}
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if (*start_ptr != obj.type && !(ctx->implicit && *objectID == 0))
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{
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logger->log(logger, ERROR|LEVEL1, "L%d - %s: ASN1 tag 0x%02x expected, but is 0x%02x",
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*level, obj.name, obj.type, *start_ptr);
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logger->log_bytes(logger, RAW|LEVEL1, "", start_ptr, (u_int)(blob->ptr - start_ptr));
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return FALSE;
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}
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logger->log(logger, CONTROL|LEVEL1, "L%d - %s:", ctx->level0+obj.level, obj.name);
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/* In case of "SEQUENCE OF" or "SET OF" start a loop */
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if (obj.flags & ASN1_LOOP)
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{
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if (blob1->len > 0)
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{
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/* at least one item, start the loop */
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ctx->loopAddr[obj.level] = *objectID + 1;
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}
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else
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{
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/* no items, advance directly to end of loop */
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do
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(*objectID)++;
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while (!((objects[*objectID].flags & ASN1_END)
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&& (objects[*objectID].level == obj.level)));
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return TRUE;
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}
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}
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if (obj.flags & ASN1_OBJ)
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{
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object->ptr = start_ptr;
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object->len = (size_t)(blob->ptr - start_ptr);
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logger->log_chunk(logger, RAW|LEVEL1, "", *object);
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}
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else if (obj.flags & ASN1_BODY)
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{
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*object = *blob1;
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debug_asn1_simple_object(*object, obj.type);
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}
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return TRUE;
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}
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/**
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* parse an ASN.1 simple type
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*/
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bool parse_asn1_simple_object(chunk_t *object, asn1_t type, u_int level, const char* name)
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{
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size_t len;
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/* an ASN.1 object must possess at least a tag and length field */
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if (object->len < 2)
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{
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logger->log(logger, ERROR|LEVEL1, "L%d - %s: ASN.1 object smaller than 2 octets",
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level, name);
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return FALSE;
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}
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if (*object->ptr != type)
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{
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logger->log(logger, ERROR|LEVEL1, "L%d - %s: ASN1 tag 0x%02x expected, but is 0x%02x",
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level, name, type, *object->ptr);
|
|
return FALSE;
|
|
}
|
|
|
|
len = asn1_length(object);
|
|
|
|
if (len == ASN1_INVALID_LENGTH || object->len < len)
|
|
{
|
|
logger->log(logger, ERROR|LEVEL1, "L%d - %s: length of ASN.1 object invalid or too large",
|
|
level, name);
|
|
return FALSE;
|
|
}
|
|
|
|
logger->log(logger, CONTROL|LEVEL1, "L%d - %s:", level, name);
|
|
debug_asn1_simple_object(*object, type);
|
|
return TRUE;
|
|
}
|
|
|
|
/**
|
|
* extracts an algorithmIdentifier
|
|
*/
|
|
int parse_algorithmIdentifier(chunk_t blob, int level0, chunk_t *parameters)
|
|
{
|
|
asn1_ctx_t ctx;
|
|
chunk_t object;
|
|
u_int level;
|
|
int alg = OID_UNKNOWN;
|
|
int objectID = 0;
|
|
|
|
asn1_init(&ctx, blob, level0, FALSE);
|
|
|
|
while (objectID < ALGORITHM_ID_ROOF)
|
|
{
|
|
if (!extract_object(algorithmIdentifierObjects, &objectID, &object, &level, &ctx))
|
|
return OID_UNKNOWN;
|
|
|
|
switch (objectID)
|
|
{
|
|
case ALGORITHM_ID_ALG:
|
|
alg = known_oid(object);
|
|
break;
|
|
case ALGORITHM_ID_PARAMETERS:
|
|
if (parameters != NULL)
|
|
*parameters = object;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
objectID++;
|
|
}
|
|
return alg;
|
|
}
|
|
|
|
/*
|
|
* tests if a blob contains a valid ASN.1 set or sequence
|
|
*/
|
|
bool is_asn1(chunk_t blob)
|
|
{
|
|
u_int len;
|
|
u_char tag = *blob.ptr;
|
|
|
|
asn1_init_logger();
|
|
|
|
if (tag != ASN1_SEQUENCE && tag != ASN1_SET)
|
|
{
|
|
logger->log(logger, ERROR|LEVEL2, " file content is not binary ASN.1");
|
|
return FALSE;
|
|
}
|
|
len = asn1_length(&blob);
|
|
if (len != blob.len)
|
|
{
|
|
logger->log(logger, ERROR|LEVEL2, " file size does not match ASN.1 coded length");
|
|
return FALSE;
|
|
}
|
|
return TRUE;
|
|
}
|
|
|
|
/**
|
|
* codes ASN.1 lengths up to a size of 16'777'215 bytes
|
|
*/
|
|
void code_asn1_length(size_t length, chunk_t *code)
|
|
{
|
|
if (length < 128)
|
|
{
|
|
code->ptr[0] = length;
|
|
code->len = 1;
|
|
}
|
|
else if (length < 256)
|
|
{
|
|
code->ptr[0] = 0x81;
|
|
code->ptr[1] = (u_char) length;
|
|
code->len = 2;
|
|
}
|
|
else if (length < 65536)
|
|
{
|
|
code->ptr[0] = 0x82;
|
|
code->ptr[1] = length >> 8;
|
|
code->ptr[2] = length & 0x00ff;
|
|
code->len = 3;
|
|
}
|
|
else
|
|
{
|
|
code->ptr[0] = 0x83;
|
|
code->ptr[1] = length >> 16;
|
|
code->ptr[2] = (length >> 8) & 0x00ff;
|
|
code->ptr[3] = length & 0x0000ff;
|
|
code->len = 4;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* build an empty asn.1 object with tag and length fields already filled in
|
|
*/
|
|
u_char* build_asn1_object(chunk_t *object, asn1_t type, size_t datalen)
|
|
{
|
|
u_char length_buf[4];
|
|
chunk_t length = { length_buf, 0 };
|
|
u_char *pos;
|
|
|
|
/* code the asn.1 length field */
|
|
code_asn1_length(datalen, &length);
|
|
|
|
/* allocate memory for the asn.1 TLV object */
|
|
object->len = 1 + length.len + datalen;
|
|
object->ptr = malloc(object->len);
|
|
|
|
/* set position pointer at the start of the object */
|
|
pos = object->ptr;
|
|
|
|
/* copy the asn.1 tag field and advance the pointer */
|
|
*pos++ = type;
|
|
|
|
/* copy the asn.1 length field and advance the pointer */
|
|
memcpy(pos, length.ptr, length.len);
|
|
pos += length.len;
|
|
|
|
return pos;
|
|
}
|
|
|
|
/**
|
|
* build a simple ASN.1 object
|
|
*/
|
|
chunk_t asn1_simple_object(asn1_t tag, chunk_t content)
|
|
{
|
|
chunk_t object;
|
|
|
|
u_char *pos = build_asn1_object(&object, tag, content.len);
|
|
memcpy(pos, content.ptr, content.len);
|
|
pos += content.len;
|
|
|
|
return object;
|
|
}
|
|
|
|
/**
|
|
* Build an ASN.1 object from a variable number of individual chunks.
|
|
* Depending on the mode, chunks either are moved ('m') or copied ('c').
|
|
*/
|
|
chunk_t asn1_wrap(asn1_t type, const char *mode, ...)
|
|
{
|
|
chunk_t construct;
|
|
va_list chunks;
|
|
u_char *pos;
|
|
int i;
|
|
int count = strlen(mode);
|
|
|
|
/* sum up lengths of individual chunks */
|
|
va_start(chunks, mode);
|
|
construct.len = 0;
|
|
for (i = 0; i < count; i++)
|
|
{
|
|
chunk_t ch = va_arg(chunks, chunk_t);
|
|
construct.len += ch.len;
|
|
}
|
|
va_end(chunks);
|
|
|
|
/* allocate needed memory for construct */
|
|
pos = build_asn1_object(&construct, type, construct.len);
|
|
|
|
/* copy or move the chunks */
|
|
va_start(chunks, mode);
|
|
for (i = 0; i < count; i++)
|
|
{
|
|
chunk_t ch = va_arg(chunks, chunk_t);
|
|
|
|
switch (*mode++)
|
|
{
|
|
case 'm':
|
|
memcpy(pos, ch.ptr, ch.len);
|
|
pos += ch.len;
|
|
free(ch.ptr);
|
|
break;
|
|
case 'c':
|
|
default:
|
|
memcpy(pos, ch.ptr, ch.len);
|
|
pos += ch.len;
|
|
}
|
|
}
|
|
va_end(chunks);
|
|
|
|
return construct;
|
|
}
|
|
|
|
/**
|
|
* convert a MP integer into a DER coded ASN.1 object
|
|
*/
|
|
chunk_t asn1_integer_from_mpz(const mpz_t value)
|
|
{
|
|
size_t bits = mpz_sizeinbase(value, 2); /* size in bits */
|
|
chunk_t n;
|
|
n.len = 1 + bits / 8; /* size in bytes */
|
|
n.ptr = mpz_export(NULL, NULL, 1, n.len, 1, 0, value);
|
|
|
|
return asn1_wrap(ASN1_INTEGER, "m", n);
|
|
}
|
|
|
|
/**
|
|
* convert a date into ASN.1 UTCTIME or GENERALIZEDTIME format
|
|
*/
|
|
chunk_t timetoasn1(const time_t *time, asn1_t type)
|
|
{
|
|
int offset;
|
|
const char *format;
|
|
char buf[TIMETOA_BUF];
|
|
chunk_t formatted_time;
|
|
struct tm *t = gmtime(time);
|
|
|
|
if (type == ASN1_GENERALIZEDTIME)
|
|
{
|
|
format = "%04d%02d%02d%02d%02d%02dZ";
|
|
offset = 1900;
|
|
}
|
|
else /* ASN1_UTCTIME */
|
|
{
|
|
format = "%02d%02d%02d%02d%02d%02dZ";
|
|
offset = (t->tm_year < 100)? 0 : -100;
|
|
}
|
|
sprintf(buf, format, t->tm_year + offset, t->tm_mon + 1, t->tm_mday
|
|
, t->tm_hour, t->tm_min, t->tm_sec);
|
|
formatted_time.ptr = buf;
|
|
formatted_time.len = strlen(buf);
|
|
return asn1_simple_object(type, formatted_time);
|
|
}
|