asn1.h

00001 /**
00002  * \file asn1.h
00003  *
00004  * \brief Generic ASN.1 parsing
00005  *
00006  *  Copyright (C) 2006-2013, ARM Limited, All Rights Reserved
00007  *
00008  *  This file is part of mbed TLS (https://tls.mbed.org)
00009  *
00010  *  This program is free software; you can redistribute it and/or modify
00011  *  it under the terms of the GNU General Public License as published by
00012  *  the Free Software Foundation; either version 2 of the License, or
00013  *  (at your option) any later version.
00014  *
00015  *  This program is distributed in the hope that it will be useful,
00016  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00017  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00018  *  GNU General Public License for more details.
00019  *
00020  *  You should have received a copy of the GNU General Public License along
00021  *  with this program; if not, write to the Free Software Foundation, Inc.,
00022  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00023  */
00024 #ifndef POLARSSL_ASN1_H
00025 #define POLARSSL_ASN1_H
00026 
00027 #if !defined(POLARSSL_CONFIG_FILE)
00028 #include "config.h"
00029 #else
00030 #include POLARSSL_CONFIG_FILE
00031 #endif
00032 
00033 #include <stddef.h>
00034 
00035 #if defined(POLARSSL_BIGNUM_C)
00036 #include "bignum.h"
00037 #endif
00038 
00039 /**
00040  * \addtogroup asn1_module
00041  * \{
00042  */
00043 
00044 /**
00045  * \name ASN1 Error codes
00046  * These error codes are OR'ed to X509 error codes for
00047  * higher error granularity.
00048  * ASN1 is a standard to specify data structures.
00049  * \{
00050  */
00051 #define POLARSSL_ERR_ASN1_OUT_OF_DATA                      -0x0060  /**< Out of data when parsing an ASN1 data structure. */
00052 #define POLARSSL_ERR_ASN1_UNEXPECTED_TAG                   -0x0062  /**< ASN1 tag was of an unexpected value. */
00053 #define POLARSSL_ERR_ASN1_INVALID_LENGTH                   -0x0064  /**< Error when trying to determine the length or invalid length. */
00054 #define POLARSSL_ERR_ASN1_LENGTH_MISMATCH                  -0x0066  /**< Actual length differs from expected length. */
00055 #define POLARSSL_ERR_ASN1_INVALID_DATA                     -0x0068  /**< Data is invalid. (not used) */
00056 #define POLARSSL_ERR_ASN1_MALLOC_FAILED                    -0x006A  /**< Memory allocation failed */
00057 #define POLARSSL_ERR_ASN1_BUF_TOO_SMALL                    -0x006C  /**< Buffer too small when writing ASN.1 data structure. */
00058 
00059 /* \} name */
00060 
00061 /**
00062  * \name DER constants
00063  * These constants comply with DER encoded the ANS1 type tags.
00064  * DER encoding uses hexadecimal representation.
00065  * An example DER sequence is:\n
00066  * - 0x02 -- tag indicating INTEGER
00067  * - 0x01 -- length in octets
00068  * - 0x05 -- value
00069  * Such sequences are typically read into \c ::x509_buf.
00070  * \{
00071  */
00072 #define ASN1_BOOLEAN                 0x01
00073 #define ASN1_INTEGER                 0x02
00074 #define ASN1_BIT_STRING              0x03
00075 #define ASN1_OCTET_STRING            0x04
00076 #define ASN1_NULL                    0x05
00077 #define ASN1_OID                     0x06
00078 #define ASN1_UTF8_STRING             0x0C
00079 #define ASN1_SEQUENCE                0x10
00080 #define ASN1_SET                     0x11
00081 #define ASN1_PRINTABLE_STRING        0x13
00082 #define ASN1_T61_STRING              0x14
00083 #define ASN1_IA5_STRING              0x16
00084 #define ASN1_UTC_TIME                0x17
00085 #define ASN1_GENERALIZED_TIME        0x18
00086 #define ASN1_UNIVERSAL_STRING        0x1C
00087 #define ASN1_BMP_STRING              0x1E
00088 #define ASN1_PRIMITIVE               0x00
00089 #define ASN1_CONSTRUCTED             0x20
00090 #define ASN1_CONTEXT_SPECIFIC        0x80
00091 /* \} name */
00092 /* \} addtogroup asn1_module */
00093 
00094 /** Returns the size of the binary string, without the trailing \\0 */
00095 #define OID_SIZE(x) (sizeof(x) - 1)
00096 
00097 /**
00098  * Compares an asn1_buf structure to a reference OID.
00099  *
00100  * Only works for 'defined' oid_str values (OID_HMAC_SHA1), you cannot use a
00101  * 'unsigned char *oid' here!
00102  *
00103  * Warning: returns true when the OIDs are equal (unlike memcmp)!
00104  */
00105 #define OID_CMP(oid_str, oid_buf)                                   \
00106         ( ( OID_SIZE(oid_str) == (oid_buf)->len ) &&                \
00107           memcmp( (oid_str), (oid_buf)->p, (oid_buf)->len) == 0 )
00108 
00109 #ifdef __cplusplus
00110 extern "C" {
00111 #endif
00112 
00113 /**
00114  * \name Functions to parse ASN.1 data structures
00115  * \{
00116  */
00117 
00118 /**
00119  * Type-length-value structure that allows for ASN1 using DER.
00120  */
00121 typedef struct _asn1_buf
00122 {
00123     int tag;                /**< ASN1 type, e.g. ASN1_UTF8_STRING. */
00124     size_t len;             /**< ASN1 length, e.g. in octets. */
00125     unsigned char *p;       /**< ASN1 data, e.g. in ASCII. */
00126 }
00127 asn1_buf;
00128 
00129 /**
00130  * Container for ASN1 bit strings.
00131  */
00132 typedef struct _asn1_bitstring
00133 {
00134     size_t len;                 /**< ASN1 length, e.g. in octets. */
00135     unsigned char unused_bits;  /**< Number of unused bits at the end of the string */
00136     unsigned char *p;           /**< Raw ASN1 data for the bit string */
00137 }
00138 asn1_bitstring;
00139 
00140 /**
00141  * Container for a sequence of ASN.1 items
00142  */
00143 typedef struct _asn1_sequence
00144 {
00145     asn1_buf buf;                   /**< Buffer containing the given ASN.1 item. */
00146     struct _asn1_sequence *next;    /**< The next entry in the sequence. */
00147 }
00148 asn1_sequence;
00149 
00150 /**
00151  * Container for a sequence or list of 'named' ASN.1 data items
00152  */
00153 typedef struct _asn1_named_data
00154 {
00155     asn1_buf oid;                   /**< The object identifier. */
00156     asn1_buf val;                   /**< The named value. */
00157     struct _asn1_named_data *next;  /**< The next entry in the sequence. */
00158     unsigned char next_merged;      /**< Merge next item into the current one? */
00159 }
00160 asn1_named_data;
00161 
00162 /**
00163  * \brief       Get the length of an ASN.1 element.
00164  *              Updates the pointer to immediately behind the length.
00165  *
00166  * \param p     The position in the ASN.1 data
00167  * \param end   End of data
00168  * \param len   The variable that will receive the value
00169  *
00170  * \return      0 if successful, POLARSSL_ERR_ASN1_OUT_OF_DATA on reaching
00171  *              end of data, POLARSSL_ERR_ASN1_INVALID_LENGTH if length is
00172  *              unparseable.
00173  */
00174 int asn1_get_len( unsigned char **p,
00175                   const unsigned char *end,
00176                   size_t *len );
00177 
00178 /**
00179  * \brief       Get the tag and length of the tag. Check for the requested tag.
00180  *              Updates the pointer to immediately behind the tag and length.
00181  *
00182  * \param p     The position in the ASN.1 data
00183  * \param end   End of data
00184  * \param len   The variable that will receive the length
00185  * \param tag   The expected tag
00186  *
00187  * \return      0 if successful, POLARSSL_ERR_ASN1_UNEXPECTED_TAG if tag did
00188  *              not match requested tag, or another specific ASN.1 error code.
00189  */
00190 int asn1_get_tag( unsigned char **p,
00191                   const unsigned char *end,
00192                   size_t *len, int tag );
00193 
00194 /**
00195  * \brief       Retrieve a boolean ASN.1 tag and its value.
00196  *              Updates the pointer to immediately behind the full tag.
00197  *
00198  * \param p     The position in the ASN.1 data
00199  * \param end   End of data
00200  * \param val   The variable that will receive the value
00201  *
00202  * \return      0 if successful or a specific ASN.1 error code.
00203  */
00204 int asn1_get_bool( unsigned char **p,
00205                    const unsigned char *end,
00206                    int *val );
00207 
00208 /**
00209  * \brief       Retrieve an integer ASN.1 tag and its value.
00210  *              Updates the pointer to immediately behind the full tag.
00211  *
00212  * \param p     The position in the ASN.1 data
00213  * \param end   End of data
00214  * \param val   The variable that will receive the value
00215  *
00216  * \return      0 if successful or a specific ASN.1 error code.
00217  */
00218 int asn1_get_int( unsigned char **p,
00219                   const unsigned char *end,
00220                   int *val );
00221 
00222 /**
00223  * \brief       Retrieve a bitstring ASN.1 tag and its value.
00224  *              Updates the pointer to immediately behind the full tag.
00225  *
00226  * \param p     The position in the ASN.1 data
00227  * \param end   End of data
00228  * \param bs    The variable that will receive the value
00229  *
00230  * \return      0 if successful or a specific ASN.1 error code.
00231  */
00232 int asn1_get_bitstring( unsigned char **p, const unsigned char *end,
00233                         asn1_bitstring *bs);
00234 
00235 /**
00236  * \brief       Retrieve a bitstring ASN.1 tag without unused bits and its
00237  *              value.
00238  *              Updates the pointer to the beginning of the bit/octet string.
00239  *
00240  * \param p     The position in the ASN.1 data
00241  * \param end   End of data
00242  * \param len   Length of the actual bit/octect string in bytes
00243  *
00244  * \return      0 if successful or a specific ASN.1 error code.
00245  */
00246 int asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
00247                              size_t *len );
00248 
00249 /**
00250  * \brief       Parses and splits an ASN.1 "SEQUENCE OF <tag>"
00251  *              Updated the pointer to immediately behind the full sequence tag.
00252  *
00253  * \param p     The position in the ASN.1 data
00254  * \param end   End of data
00255  * \param cur   First variable in the chain to fill
00256  * \param tag   Type of sequence
00257  *
00258  * \return      0 if successful or a specific ASN.1 error code.
00259  */
00260 int asn1_get_sequence_of( unsigned char **p,
00261                           const unsigned char *end,
00262                           asn1_sequence *cur,
00263                           int tag);
00264 
00265 #if defined(POLARSSL_BIGNUM_C)
00266 /**
00267  * \brief       Retrieve a MPI value from an integer ASN.1 tag.
00268  *              Updates the pointer to immediately behind the full tag.
00269  *
00270  * \param p     The position in the ASN.1 data
00271  * \param end   End of data
00272  * \param X     The MPI that will receive the value
00273  *
00274  * \return      0 if successful or a specific ASN.1 or MPI error code.
00275  */
00276 int asn1_get_mpi( unsigned char **p,
00277                   const unsigned char *end,
00278                   mpi *X );
00279 #endif /* POLARSSL_BIGNUM_C */
00280 
00281 /**
00282  * \brief       Retrieve an AlgorithmIdentifier ASN.1 sequence.
00283  *              Updates the pointer to immediately behind the full
00284  *              AlgorithmIdentifier.
00285  *
00286  * \param p     The position in the ASN.1 data
00287  * \param end   End of data
00288  * \param alg   The buffer to receive the OID
00289  * \param params The buffer to receive the params (if any)
00290  *
00291  * \return      0 if successful or a specific ASN.1 or MPI error code.
00292  */
00293 int asn1_get_alg( unsigned char **p,
00294                   const unsigned char *end,
00295                   asn1_buf *alg, asn1_buf *params );
00296 
00297 /**
00298  * \brief       Retrieve an AlgorithmIdentifier ASN.1 sequence with NULL or no
00299  *              params.
00300  *              Updates the pointer to immediately behind the full
00301  *              AlgorithmIdentifier.
00302  *
00303  * \param p     The position in the ASN.1 data
00304  * \param end   End of data
00305  * \param alg   The buffer to receive the OID
00306  *
00307  * \return      0 if successful or a specific ASN.1 or MPI error code.
00308  */
00309 int asn1_get_alg_null( unsigned char **p,
00310                        const unsigned char *end,
00311                        asn1_buf *alg );
00312 
00313 /**
00314  * \brief       Find a specific named_data entry in a sequence or list based on
00315  *              the OID.
00316  *
00317  * \param list  The list to seek through
00318  * \param oid   The OID to look for
00319  * \param len   Size of the OID
00320  *
00321  * \return      NULL if not found, or a pointer to the existing entry.
00322  */
00323 asn1_named_data *asn1_find_named_data( asn1_named_data *list,
00324                                        const char *oid, size_t len );
00325 
00326 /**
00327  * \brief       Free a asn1_named_data entry
00328  *
00329  * \param entry The named data entry to free
00330  */
00331 void asn1_free_named_data( asn1_named_data *entry );
00332 
00333 /**
00334  * \brief       Free all entries in a asn1_named_data list
00335  *              Head will be set to NULL
00336  *
00337  * \param head  Pointer to the head of the list of named data entries to free
00338  */
00339 void asn1_free_named_data_list( asn1_named_data **head );
00340 
00341 #ifdef __cplusplus
00342 }
00343 #endif
00344 
00345 #endif /* asn1.h */
00346