Provided by: openswan_2.4.12+dfsg-1.3_i386 bug

NAME

       ipsec  ttodata,  datatot  -  convert binary data bytes from and to text
       formats

SYNOPSIS

       #include <freeswan.h>

       const char *ttodata(const char *src, size_t srclen,
           int base, char *dst, size_t dstlen, size_t *lenp);
       const char *ttodatav(const char *src, size_t srclen,
           int base, char *dst, size_t dstlen, size_t *lenp,
           char *errp, size_t errlen, int flags);
       size_t datatot(const char *src, size_t srclen,
           int format, char *dst, size_t dstlen);

DESCRIPTION

       Ttodata, ttodatav, and datatot  convert  arbitrary  binary  data  (e.g.
       encryption  or  authentication  keys)  from  and to more-or-less human-
       readable text formats.

       Currently supported formats are hexadecimal, base64, and characters.

       A hexadecimal text value begins with a 0x (or 0X) prefix and  continues
       with two-digit groups of hexadecimal digits (0-9, and a-f or A-F), each
       group encoding the value of one binary byte, high-order digit first.  A
       single _ (underscore) between consecutive groups is ignored, permitting
       punctuation to improve readability; doing this every eight digits seems
       about right.

       A  base64 text value begins with a 0s (or 0S) prefix and continues with
       four-digit groups of base64 digits (A-Z, a-z,  0-9,  +,  and  /),  each
       group  encoding the value of three binary bytes as described in section
       6.8 of RFC 2045.  If flags has the TTODATAV_IGNORESPACE bit on,  blanks
       are ignore (after the prefix).  Note that the last one or two digits of
       a base64 group can be = to indicate that fewer than three binary  bytes
       are encoded.

       A  character  text  value begins with a 0t (or 0T) prefix and continues
       with text characters, each being the value of one binary byte.

       All these functions  basically  copy  data  from  src  (whose  size  is
       specified  by srclen) to dst (whose size is specified by dstlen), doing
       the conversion en route.  If the result will not  fit  in  dst,  it  is
       truncated;  under no circumstances are more than dstlen bytes of result
       written to dst.  Dstlen can be zero, in which  case  dst  need  not  be
       valid and no result bytes are written at all.

       The  base  parameter  of ttodata and ttodatav specifies what format the
       input is in; normally it should be 0 to signify that this gets  figured
       out  from  the  prefix.  Values of 16, 64, and 256 respectively signify
       hexadecimal, base64, and character-text formats without prefixes.

       The format parameter of datatot, a single  character  used  as  a  type
       code,  specifies  which  text format is wanted.  The value 0 (not ASCII
       ’0’,  but  a  zero  value)  specifies  a  reasonable  default.    Other
       currently-supported values are:

         ’x’ continuous lower-case hexadecimal with a 0x prefix

         ’h’ lower-case  hexadecimal  with  a  0x  prefix  and a _ every eight
             digits

         ’:’ lower-case hexadecimal with no prefix and a : (colon)  every  two
             digits

         16  lower-case hexadecimal with no prefix or _s’ continuous base64 with a 0s prefix

         64  continuous base64 with no prefix

       The default format is currently ’h’.

       Ttodata  returns  NULL  for  success  and a pointer to a string-literal
       error message for failure; see DIAGNOSTICS.  On success, if and only if
       lenp  is  non-NULL,  *lenp  is  set  to the number of bytes required to
       contain the full untruncated result.  It is the caller’s responsibility
       to  check  this  against  dstlen to determine whether he has obtained a
       complete result.  The *lenp value is correct even if  dstlen  is  zero,
       which  offers  a way to determine how much space would be needed before
       having to allocate any.

       Ttodatav is just like ttodata except that in certain cases, if errp  is
       non-NULL,  the  buffer  pointed  to  by  errp (whose length is given by
       errlen) is used to hold a more  detailed  error  message.   The  return
       value  is NULL for success, and is either errp or a pointer to a string
       literal for failure.  If  the  size  of  the  error-message  buffer  is
       inadequate  for  the  desired  message,  ttodatav  will  fall  back  on
       returning a pointer to a literal string instead.  The freeswan.h header
       file  defines  a  constant  TTODATAV_BUF  which is the size of a buffer
       large enough for worst-case results.

       The normal return value of datatot is the number of bytes  required  to
       contain the full untruncated result.  It is the caller’s responsibility
       to check this against dstlen to determine whether  he  has  obtained  a
       complete  result.   The return value is correct even if dstlen is zero,
       which offers a way to determine how much space would be  needed  before
       having  to  allocate any.  A return value of 0 signals a fatal error of
       some kind (see DIAGNOSTICS).

       A zero value for srclen in ttodata (but not  datatot!)   is  synonymous
       with  strlen(src).   A  non-zero srclen in ttodata must not include the
       terminating NUL.

       Unless dstlen is zero, the result supplied by datatot  is  always  NUL-
       terminated,  and  its  needed-size  return value includes space for the
       terminating NUL.

       Several  obsolete  variants  of  these  functions  (atodata,   datatoa,
       atobytes, and bytestoa) are temporarily also supported.

SEE ALSO

       sprintf(3), ipsec_atoaddr(3)

DIAGNOSTICS

       Fatal  errors  in  ttodata  and ttodatav are: unknown characters in the
       input; unknown or missing prefix; unknown base; incomplete digit group;
       non-zero  padding  in a base64 less-than-three-bytes digit group; zero-
       length input.

       Fatal errors in datatot are: unknown format code; zero-length input.

HISTORY

       Written for the FreeS/WAN project by Henry Spencer.

BUGS

       Datatot should have a format code to produce character-text output.

       The 0s and 0t prefixes are  the  author’s  inventions  and  are  not  a
       standard  of  any kind.  They have been chosen to avoid collisions with
       existing practice (some  C  implementations  use  0b  for  binary)  and
       possible confusion with unprefixed hexadecimal.

                                16 August 2003                IPSEC_TTODATA(3)