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idn_decodename(3)     DragonFly Library Functions Manual     idn_decodename(3)

NAME
       idn_decodename, idn_decodename2 - decode an internationalized domain
       name

SYNOPSIS
       #include <idn/api.h>

       idn_result_t
       idn_decodename(idn_action_t actions, const char *from, char *to,
           size_t tolen);

       idn_result_t
       idn_decodename2(idn_action_t actions, const char *from, char *to,
           size_t tolen, const char *auxencoding);

DESCRIPTION
       The function idn_decodename() decodes a domain name from and writes the
       result on to, at most tolen bytes.  Note that from must be terminated
       by NUL, and tolen includes room for a NUL character.

       The argument actions specifies which steps in the entire decoding
       process should be performed. The following list shows action names
       corresponding with steps of the decoding process. The function performs
       the steps in that order.

           1. IDN_UNICODECONV
                  Convert a domain name from local decoding (e.g. ISO-8859-1)
                  to UTF-8.

           2. IDN_MAP
                  Perform mappings (NFC, Lowercase conversion, etc.).

           3. IDN_ASCLOWER
                  Convert ASCII uppercase letters (A..Z) to lowercase (a..z).

           4. IDN_IDNCONV
                  Convert A-labels to U-labels.

           5. IDN_PROHCHECK
                  Check prohibited code points.

           6. IDN_UNASCHECK
                  Check unassigned code points.

           7. IDN_NFCCHECK
                  Check labels are in NFC.

           8. IDN_PREFCHECK
                  Check labels containing "--" in the 3rd and 4th characters.

           9. IDN_HYPHCHECK
                  Check labels beginning/ending with "-".

           10. IDN_COMBCHECK
                  Check labels beginning with a combining mark.

           11. IDN_CTXJCHECK
                  Check CONTEXTJ code points.

           12a. IDN_CTXOCHECK
                  Check CONTEXTO code points for the registration protocol.

           12b. IDN_CTXOLITECHECK
                  Check CONTEXTO code points for the lookup protocol.

           13. IDN_BIDICHECK
                  Check requirements specified in [IDNA2008-BIDI].

           14. IDN_LOCALCHECK
                  Perform local check (optional).

           15. IDN_RTCHECK
                  Perform round trip check for each label.

           16. IDN_LOCALCONV
                  Convert a domain name from UTF-8 to local encoding (e.g.
                  ISO-8859-1).

       Between the step 2 and 3, the domain name is split into labels.  The
       step 3 through 15 are applied to each label. After the step 15, labels
       are joined with a separator ``.''.

       A value of bitwise-OR of some actions can be specified, like:

           r = idn_decodename(IDN_IDNCONV | IDN_LOCALCONV, from, to, tolen);

       The function idn_decodename2() works same as idn_decodename(), but an
       encoding conversion from auxencoding to UTF-8 is performed prior to the
       actual decoding process.  Instead, idn_decodename2() ignores
       IDN_UNICODECONV action.  If auxencoding is NULL, from is treated as
       UTF-8.

       Also the following actions are provided for convenience:

           IDN_DECODE_REGIST
                  Decode a domain name with IDNA2008 registration protocol.
                  libidnkit performs the step 1..11, 12a, 13, 15 and 16.
                  libidnkitlite performs the step 2..11, 12a, 13 and 15.

           IDN_DECODE_LOOKUP
                  Decode a domain name with IDNA2008 lookup protocol.
                  libidnkit performs the step 1..8, 10, 11, 12b, 13, 15 and
                  16.  libidnkitlite performs the step 2..8, 10, 11, 12b, 13
                  and 15.

       Upon success, the functions returns idn_success.  Otherwise, it returns
       an error code.  See idn_result_tostring(3) for the complete list of
       error codes.

EXAMPLE
       To decode an internationalized domain name returned from a resolver
       function, use idn_decodename().

           idn_result_t r;
           char ace_name[256];
           struct hostent *hp;

           ...
           hp = gethostbyname(name);
           r = idn_decodename(IDN_DECODE_LOOKUP, hp->h_name, local_name,
                              sizeof(local_name));
           if (r != idn_success) {
               fprintf(stderr, "idn_decodename failed: %s\n",
                       idn_result_tostring(r));
               exit(1);
           }
           printf("name: %s\n", local_name);
           ...

SEE ALSO
       idnconv(1), libidnkit(3), idn_nameinit(3), idn_result_tostring(3),
       idn2.conf(5)

                              September 21, 2012             idn_decodename(3)