Manual Pages for UNIX Operating System command usage for man d2i_X509_fp

OpenSSL                                        d2i_X509(3openssl)



NNNNAAAAMMMMEEEE
     d2i_X509, i2d_X509, d2i_X509_bio, d2i_X509_fp, i2d_X509_bio,
     i2d_X509_fp - X509 encode and decode functions

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
      #include 

      X509 *d2i_X509(X509 **px, const unsigned char **in, int len);
      int i2d_X509(X509 *x, unsigned char **out);

      X509 *d2i_X509_bio(BIO *bp, X509 **x);
      X509 *d2i_X509_fp(FILE *fp, X509 **x);

      int i2d_X509_bio(BIO *bp, X509 *x);
      int i2d_X509_fp(FILE *fp, X509 *x);


DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     The X509 encode and decode routines encode and parse an XXXX555500009999
     structure, which represents an X509 certificate.

     d2i_X509() attempts to decode lllleeeennnn bytes at ****iiiinnnn. If
     successful a pointer to the XXXX555500009999 structure is returned. If
     an error occurred then NNNNUUUULLLLLLLL is returned. If ppppxxxx is not NNNNUUUULLLLLLLL
     then the returned structure is written to ****ppppxxxx. If ****ppppxxxx is not
     NNNNUUUULLLLLLLL then it is assumed that ****ppppxxxx contains a valid XXXX555500009999
     structure and an attempt is made to reuse it. If the call is
     successful ****iiiinnnn is incremented to the byte following the
     parsed data.

     i2d_X509() encodes the structure pointed to by xxxx into DER
     format.  If oooouuuutttt is not NNNNUUUULLLLLLLL is writes the DER encoded data
     to the buffer at ****oooouuuutttt, and increments it to point after the
     data just written.  If the return value is negative an error
     occurred, otherwise it returns the length of the encoded
     data.

     For OpenSSL 0.9.7 and later if ****oooouuuutttt is NNNNUUUULLLLLLLL memory will be
     allocated for a buffer and the encoded data written to it.
     In this case ****oooouuuutttt is not incremented and it points to the
     start of the data just written.

     d2i_X509_bio() is similar to d2i_X509() except it attempts
     to parse data from BIO bbbbpppp.

     d2i_X509_fp() is similar to d2i_X509() except it attempts to
     parse data from FILE pointer ffffpppp.

     i2d_X509_bio() is similar to i2d_X509() except it writes the
     encoding of the structure xxxx to BIO bbbbpppp and it returns 1 for
     success and 0 for failure.




12/Sep/2009            Last change: 0.9.8o                      1






OpenSSL                                        d2i_X509(3openssl)



     i2d_X509_fp() is similar to i2d_X509() except it writes the
     encoding of the structure xxxx to BIO bbbbpppp and it returns 1 for
     success and 0 for failure.

NNNNOOOOTTTTEEEESSSS
     The letters iiii and dddd in for example iiii2222dddd_XXXX555500009999 stand for
     "internal" (that is an internal C structure) and "DER". So
     that iiii2222dddd_XXXX555500009999 converts from internal to DER.

     The functions can also understand BBBBEEEERRRR forms.

     The actual X509 structure passed to i2d_X509() must be a
     valid populated XXXX555500009999 structure it can nnnnooootttt simply be fed with
     an empty structure such as that returned by X509_new().

     The encoded data is in binary form and may contain embedded
     zeroes.  Therefore any FILE pointers or BIOs should be
     opened in binary mode.  Functions such as ssssttttrrrrlllleeeennnn(((()))) will nnnnooootttt
     return the correct length of the encoded structure.

     The ways that ****iiiinnnn and ****oooouuuutttt are incremented after the
     operation can trap the unwary. See the WWWWAAAARRRRNNNNIIIINNNNGGGGSSSS section for
     some common errors.

     The reason for the auto increment behaviour is to reflect a
     typical usage of ASN1 functions: after one structure is
     encoded or decoded another will processed after it.

EEEEXXXXAAAAMMMMPPPPLLLLEEEESSSS
     Allocate and encode the DER encoding of an X509 structure:

      int len;
      unsigned char *buf, *p;

      len = i2d_X509(x, NULL);

      buf = OPENSSL_malloc(len);

      if (buf == NULL)
             /* error */

      p = buf;

      i2d_X509(x, &p);

     If you are using OpenSSL 0.9.7 or later then this can be
     simplified to:

      int len;
      unsigned char *buf;

      buf = NULL;



12/Sep/2009            Last change: 0.9.8o                      2






OpenSSL                                        d2i_X509(3openssl)



      len = i2d_X509(x, &buf);

      if (len < 0)
             /* error */

     Attempt to decode a buffer:

      X509 *x;

      unsigned char *buf, *p;

      int len;

      /* Something to setup buf and len */

      p = buf;

      x = d2i_X509(NULL, &p, len);

      if (x == NULL)
         /* Some error */

     Alternative technique:

      X509 *x;

      unsigned char *buf, *p;

      int len;

      /* Something to setup buf and len */

      p = buf;

      x = NULL;

      if(!d2i_X509(&x, &p, len))
         /* Some error */


WWWWAAAARRRRNNNNIIIINNNNGGGGSSSS
     The use of temporary variable is mandatory. A common mistake
     is to attempt to use a buffer directly as follows:

      int len;
      unsigned char *buf;

      len = i2d_X509(x, NULL);

      buf = OPENSSL_malloc(len);





12/Sep/2009            Last change: 0.9.8o                      3






OpenSSL                                        d2i_X509(3openssl)



      if (buf == NULL)
             /* error */

      i2d_X509(x, &buf);

      /* Other stuff ... */

      OPENSSL_free(buf);

     This code will result in bbbbuuuuffff apparently containing garbage
     because it was incremented after the call to point after the
     data just written.  Also bbbbuuuuffff will no longer contain the
     pointer allocated by OOOOPPPPEEEENNNNSSSSSSSSLLLL_mmmmaaaalllllllloooocccc(((()))) and the subsequent
     call to OOOOPPPPEEEENNNNSSSSSSSSLLLL_ffffrrrreeeeeeee(((()))) may well crash.

     The auto allocation feature (setting buf to NULL) only works
     on OpenSSL 0.9.7 and later. Attempts to use it on earlier
     versions will typically cause a segmentation violation.

     Another trap to avoid is misuse of the xxxxpppp argument to
     dddd2222iiii_XXXX555500009999(((()))):

      X509 *x;

      if (!d2i_X509(&x, &p, len))
             /* Some error */

     This will probably crash somewhere in dddd2222iiii_XXXX555500009999(((()))). The reason
     for this is that the variable xxxx is uninitialized and an
     attempt will be made to interpret its (invalid) value as an
     XXXX555500009999 structure, typically causing a segmentation violation.
     If xxxx is set to NULL first then this will not happen.

BBBBUUUUGGGGSSSS
     In some versions of OpenSSL the "reuse" behaviour of
     d2i_X509() when ****ppppxxxx is valid is broken and some parts of the
     reused structure may persist if they are not present in the
     new one. As a result the use of this "reuse" behaviour is
     strongly discouraged.

     i2d_X509() will not return an error in many versions of
     OpenSSL, if mandatory fields are not initialized due to a
     programming error then the encoded structure may contain
     invalid data or omit the fields entirely and will not be
     parsed by d2i_X509(). This may be fixed in future so code
     should not assume that i2d_X509() will always succeed.

RRRREEEETTTTUUUURRRRNNNN VVVVAAAALLLLUUUUEEEESSSS
     d2i_X509(), d2i_X509_bio() and d2i_X509_fp() return a valid
     XXXX555500009999 structure or NNNNUUUULLLLLLLL if an error occurs. The error code
     that can be obtained by ERR_get_error(3).




12/Sep/2009            Last change: 0.9.8o                      4






OpenSSL                                        d2i_X509(3openssl)



     i2d_X509() returns the number of bytes successfully encoded
     or a negative value if an error occurs. The error code can
     be obtained by ERR_get_error(3).

     i2d_X509_bio() and i2d_X509_fp() return 1 for success and 0
     if an error occurs The error code can be obtained by
     ERR_get_error(3).

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     ERR_get_error(3)

HHHHIIIISSSSTTTTOOOORRRRYYYY
     d2i_X509, i2d_X509, d2i_X509_bio, d2i_X509_fp, i2d_X509_bio
     and i2d_X509_fp are available in all versions of SSLeay and
     OpenSSL.








































12/Sep/2009            Last change: 0.9.8o                      5