asn1.h

00001 /**
00002  * \file asn1.h
00003  *
00004  * \brief Generic ASN.1 parsing
00005  *
00006  *  Copyright (C) 2006-2013, Brainspark B.V.
00007  *
00008  *  This file is part of PolarSSL (http://www.polarssl.org)
00009  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
00010  *
00011  *  All rights reserved.
00012  *
00013  *  This program is free software; you can redistribute it and/or modify
00014  *  it under the terms of the GNU General Public License as published by
00015  *  the Free Software Foundation; either version 2 of the License, or
00016  *  (at your option) any later version.
00017  *
00018  *  This program is distributed in the hope that it will be useful,
00019  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00020  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00021  *  GNU General Public License for more details.
00022  *
00023  *  You should have received a copy of the GNU General Public License along
00024  *  with this program; if not, write to the Free Software Foundation, Inc.,
00025  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00026  */
00027 #ifndef POLARSSL_ASN1_H
00028 #define POLARSSL_ASN1_H
00029 
00030 #if !defined(POLARSSL_CONFIG_FILE)
00031 #include "config.h"
00032 #else
00033 #include POLARSSL_CONFIG_FILE
00034 #endif
00035 
00036 #if defined(POLARSSL_BIGNUM_C)
00037 #include "bignum.h"
00038 #endif
00039 
00040 #include <string.h>
00041 
00042 /**
00043  * \addtogroup asn1_module
00044  * \{
00045  */
00046 
00047 /**
00048  * \name ASN1 Error codes
00049  * These error codes are OR'ed to X509 error codes for
00050  * higher error granularity.
00051  * ASN1 is a standard to specify data structures.
00052  * \{
00053  */
00054 #define POLARSSL_ERR_ASN1_OUT_OF_DATA                      -0x0060  /**< Out of data when parsing an ASN1 data structure. */
00055 #define POLARSSL_ERR_ASN1_UNEXPECTED_TAG                   -0x0062  /**< ASN1 tag was of an unexpected value. */
00056 #define POLARSSL_ERR_ASN1_INVALID_LENGTH                   -0x0064  /**< Error when trying to determine the length or invalid length. */
00057 #define POLARSSL_ERR_ASN1_LENGTH_MISMATCH                  -0x0066  /**< Actual length differs from expected length. */
00058 #define POLARSSL_ERR_ASN1_INVALID_DATA                     -0x0068  /**< Data is invalid. (not used) */
00059 #define POLARSSL_ERR_ASN1_MALLOC_FAILED                    -0x006A  /**< Memory allocation failed */
00060 #define POLARSSL_ERR_ASN1_BUF_TOO_SMALL                    -0x006C  /**< Buffer too small when writing ASN.1 data structure. */
00061 
00062 /* \} name */
00063 
00064 /**
00065  * \name DER constants
00066  * These constants comply with DER encoded the ANS1 type tags.
00067  * DER encoding uses hexadecimal representation.
00068  * An example DER sequence is:\n
00069  * - 0x02 -- tag indicating INTEGER
00070  * - 0x01 -- length in octets
00071  * - 0x05 -- value
00072  * Such sequences are typically read into \c ::x509_buf.
00073  * \{
00074  */
00075 #define ASN1_BOOLEAN                 0x01
00076 #define ASN1_INTEGER                 0x02
00077 #define ASN1_BIT_STRING              0x03
00078 #define ASN1_OCTET_STRING            0x04
00079 #define ASN1_NULL                    0x05
00080 #define ASN1_OID                     0x06
00081 #define ASN1_UTF8_STRING             0x0C
00082 #define ASN1_SEQUENCE                0x10
00083 #define ASN1_SET                     0x11
00084 #define ASN1_PRINTABLE_STRING        0x13
00085 #define ASN1_T61_STRING              0x14
00086 #define ASN1_IA5_STRING              0x16
00087 #define ASN1_UTC_TIME                0x17
00088 #define ASN1_GENERALIZED_TIME        0x18
00089 #define ASN1_UNIVERSAL_STRING        0x1C
00090 #define ASN1_BMP_STRING              0x1E
00091 #define ASN1_PRIMITIVE               0x00
00092 #define ASN1_CONSTRUCTED             0x20
00093 #define ASN1_CONTEXT_SPECIFIC        0x80
00094 /* \} name */
00095 /* \} addtogroup asn1_module */
00096 
00097 /** Returns the size of the binary string, without the trailing \\0 */
00098 #define OID_SIZE(x) (sizeof(x) - 1)
00099 
00100 /** Compares two asn1_buf structures for the same OID. Only works for
00101  *  'defined' oid_str values (OID_HMAC_SHA1), you cannot use a 'unsigned
00102  *  char *oid' here!
00103  */
00104 #define OID_CMP(oid_str, oid_buf)                                   \
00105         ( ( OID_SIZE(oid_str) == (oid_buf)->len ) &&                \
00106           memcmp( (oid_str), (oid_buf)->p, (oid_buf)->len) == 0 )
00107 
00108 #ifdef __cplusplus
00109 extern "C" {
00110 #endif
00111 
00112 /**
00113  * \name Functions to parse ASN.1 data structures
00114  * \{
00115  */
00116 
00117 /**
00118  * Type-length-value structure that allows for ASN1 using DER.
00119  */
00120 typedef struct _asn1_buf
00121 {
00122     int tag;                /**< ASN1 type, e.g. ASN1_UTF8_STRING. */
00123     size_t len;             /**< ASN1 length, e.g. in octets. */
00124     unsigned char *p;       /**< ASN1 data, e.g. in ASCII. */
00125 }
00126 asn1_buf;
00127 
00128 /**
00129  * Container for ASN1 bit strings.
00130  */
00131 typedef struct _asn1_bitstring
00132 {
00133     size_t len;                 /**< ASN1 length, e.g. in octets. */
00134     unsigned char unused_bits;  /**< Number of unused bits at the end of the string */
00135     unsigned char *p;           /**< Raw ASN1 data for the bit string */
00136 }
00137 asn1_bitstring;
00138 
00139 /**
00140  * Container for a sequence of ASN.1 items
00141  */
00142 typedef struct _asn1_sequence
00143 {
00144     asn1_buf buf;                   /**< Buffer containing the given ASN.1 item. */
00145     struct _asn1_sequence *next;    /**< The next entry in the sequence. */
00146 }
00147 asn1_sequence;
00148 
00149 /**
00150  * Container for a sequence or list of 'named' ASN.1 data items
00151  */
00152 typedef struct _asn1_named_data
00153 {
00154     asn1_buf oid;                   /**< The object identifier. */
00155     asn1_buf val;                   /**< The named value. */
00156     struct _asn1_named_data *next;  /**< The next entry in the sequence. */
00157 }
00158 asn1_named_data;
00159 
00160 /**
00161  * \brief       Get the length of an ASN.1 element.
00162  *              Updates the pointer to immediately behind the length.
00163  *
00164  * \param p     The position in the ASN.1 data
00165  * \param end   End of data
00166  * \param len   The variable that will receive the value
00167  *
00168  * \return      0 if successful, POLARSSL_ERR_ASN1_OUT_OF_DATA on reaching
00169  *              end of data, POLARSSL_ERR_ASN1_INVALID_LENGTH if length is
00170  *              unparseable.
00171  */
00172 int asn1_get_len( unsigned char **p,
00173                   const unsigned char *end,
00174                   size_t *len );
00175 
00176 /**
00177  * \brief       Get the tag and length of the tag. Check for the requested tag.
00178  *              Updates the pointer to immediately behind the tag and length.
00179  *
00180  * \param p     The position in the ASN.1 data
00181  * \param end   End of data
00182  * \param len   The variable that will receive the length
00183  * \param tag   The expected tag
00184  *
00185  * \return      0 if successful, POLARSSL_ERR_ASN1_UNEXPECTED_TAG if tag did
00186  *              not match requested tag, or another specific ASN.1 error code.
00187  */
00188 int asn1_get_tag( unsigned char **p,
00189                   const unsigned char *end,
00190                   size_t *len, int tag );
00191 
00192 /**
00193  * \brief       Retrieve a boolean ASN.1 tag and its value.
00194  *              Updates the pointer to immediately behind the full tag.
00195  *
00196  * \param p     The position in the ASN.1 data
00197  * \param end   End of data
00198  * \param val   The variable that will receive the value
00199  *
00200  * \return      0 if successful or a specific ASN.1 error code.
00201  */
00202 int asn1_get_bool( unsigned char **p,
00203                    const unsigned char *end,
00204                    int *val );
00205 
00206 /**
00207  * \brief       Retrieve an integer ASN.1 tag and its value.
00208  *              Updates the pointer to immediately behind the full tag.
00209  *
00210  * \param p     The position in the ASN.1 data
00211  * \param end   End of data
00212  * \param val   The variable that will receive the value
00213  *
00214  * \return      0 if successful or a specific ASN.1 error code.
00215  */
00216 int asn1_get_int( unsigned char **p,
00217                   const unsigned char *end,
00218                   int *val );
00219 
00220 /**
00221  * \brief       Retrieve a bitstring ASN.1 tag and its value.
00222  *              Updates the pointer to immediately behind the full tag.
00223  *
00224  * \param p     The position in the ASN.1 data
00225  * \param end   End of data
00226  * \param bs    The variable that will receive the value
00227  *
00228  * \return      0 if successful or a specific ASN.1 error code.
00229  */
00230 int asn1_get_bitstring( unsigned char **p, const unsigned char *end,
00231                         asn1_bitstring *bs);
00232 
00233 /**
00234  * \brief       Retrieve a bitstring ASN.1 tag without unused bits and its
00235  *              value.
00236  *              Updates the pointer to the beginning of the bit/octet string.
00237  *
00238  * \param p     The position in the ASN.1 data
00239  * \param end   End of data
00240  * \param len   Length of the actual bit/octect string in bytes
00241  *
00242  * \return      0 if successful or a specific ASN.1 error code.
00243  */
00244 int asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
00245                              size_t *len );
00246 
00247 /**
00248  * \brief       Parses and splits an ASN.1 "SEQUENCE OF <tag>"
00249  *              Updated the pointer to immediately behind the full sequence tag.
00250  *
00251  * \param p     The position in the ASN.1 data
00252  * \param end   End of data
00253  * \param cur   First variable in the chain to fill
00254  * \param tag   Type of sequence
00255  *
00256  * \return      0 if successful or a specific ASN.1 error code.
00257  */
00258 int asn1_get_sequence_of( unsigned char **p,
00259                           const unsigned char *end,
00260                           asn1_sequence *cur,
00261                           int tag);
00262 
00263 #if defined(POLARSSL_BIGNUM_C)
00264 /**
00265  * \brief       Retrieve a MPI value from an integer ASN.1 tag.
00266  *              Updates the pointer to immediately behind the full tag.
00267  *
00268  * \param p     The position in the ASN.1 data
00269  * \param end   End of data
00270  * \param X     The MPI that will receive the value
00271  *
00272  * \return      0 if successful or a specific ASN.1 or MPI error code.
00273  */
00274 int asn1_get_mpi( unsigned char **p,
00275                   const unsigned char *end,
00276                   mpi *X );
00277 #endif /* POLARSSL_BIGNUM_C */
00278 
00279 /**
00280  * \brief       Retrieve an AlgorithmIdentifier ASN.1 sequence.
00281  *              Updates the pointer to immediately behind the full
00282  *              AlgorithmIdentifier.
00283  *
00284  * \param p     The position in the ASN.1 data
00285  * \param end   End of data
00286  * \param alg   The buffer to receive the OID
00287  * \param params The buffer to receive the params (if any)
00288  *
00289  * \return      0 if successful or a specific ASN.1 or MPI error code.
00290  */
00291 int asn1_get_alg( unsigned char **p,
00292                   const unsigned char *end,
00293                   asn1_buf *alg, asn1_buf *params );
00294 
00295 /**
00296  * \brief       Retrieve an AlgorithmIdentifier ASN.1 sequence with NULL or no
00297  *              params.
00298  *              Updates the pointer to immediately behind the full
00299  *              AlgorithmIdentifier.
00300  *
00301  * \param p     The position in the ASN.1 data
00302  * \param end   End of data
00303  * \param alg   The buffer to receive the OID
00304  *
00305  * \return      0 if successful or a specific ASN.1 or MPI error code.
00306  */
00307 int asn1_get_alg_null( unsigned char **p,
00308                        const unsigned char *end,
00309                        asn1_buf *alg );
00310 
00311 /**
00312  * \brief       Find a specific named_data entry in a sequence or list based on
00313  *              the OID.
00314  *
00315  * \param list  The list to seek through
00316  * \param oid   The OID to look for
00317  * \param len   Size of the OID
00318  *
00319  * \return      NULL if not found, or a pointer to the existing entry.
00320  */
00321 asn1_named_data *asn1_find_named_data( asn1_named_data *list,
00322                                        const char *oid, size_t len );
00323 
00324 /**
00325  * \brief       Free a asn1_named_data entry
00326  *
00327  * \param entry The named data entry to free
00328  */
00329 void asn1_free_named_data( asn1_named_data *entry );
00330 
00331 /**
00332  * \brief       Free all entries in a asn1_named_data list
00333  *              Head will be set to NULL
00334  *
00335  * \param head  Pointer to the head of the list of named data entries to free
00336  */
00337 void asn1_free_named_data_list( asn1_named_data **head );
00338 
00339 #ifdef __cplusplus
00340 }
00341 #endif
00342 
00343 #endif /* asn1.h */
00344 
00345