This example demonstrates how the library is used to check a string for invalid characters within a specific TLD.
#include <stdio.h> #include <stdlib.h> #include <string.h> /* Get stringprep_locale_charset, etc. */ #include <stringprep.h> /* Get idna_to_ascii_8z, etc. */ #include <idna.h> /* Get tld_check_4z. */ #include <tld.h> /* * Compiling using libtool and pkg-config is recommended: * * $ libtool cc -o example5 example5.c `pkg-config --cflags --libs libidn` * $ ./example5 * Input domain encoded as `UTF-8': fooß.no * Read string (length 8): 66 6f 6f c3 9f 2e 6e 6f * ToASCII string (length 8): fooss.no * ToUnicode string: U+0066 U+006f U+006f U+0073 U+0073 U+002e U+006e U+006f * Domain accepted by TLD check * * $ ./example5 * Input domain encoded as `UTF-8': gr€€n.no * Read string (length 12): 67 72 e2 82 ac e2 82 ac 6e 2e 6e 6f * ToASCII string (length 16): xn--grn-l50aa.no * ToUnicode string: U+0067 U+0072 U+20ac U+20ac U+006e U+002e U+006e U+006f * Domain rejected by TLD check, Unicode position 2 * */ int main (void) { char buf[BUFSIZ]; char *p; uint32_t *r; int rc; size_t errpos, i; printf ("Input domain encoded as `%s': ", stringprep_locale_charset ()); fflush (stdout); if (!fgets (buf, BUFSIZ, stdin)) perror ("fgets"); buf[strlen (buf) - 1] = '\0'; printf ("Read string (length %ld): ", (long int) strlen (buf)); for (i = 0; i < strlen (buf); i++) printf ("%02x ", (unsigned) buf[i] & 0xFF); printf ("\n"); p = stringprep_locale_to_utf8 (buf); if (p) { strcpy (buf, p); free (p); } else printf ("Could not convert string to UTF-8, continuing anyway...\n"); rc = idna_to_ascii_8z (buf, &p, 0); if (rc != IDNA_SUCCESS) { printf ("idna_to_ascii_8z failed (%d): %s\n", rc, idna_strerror (rc)); return 2; } printf ("ToASCII string (length %ld): %s\n", (long int) strlen (p), p); rc = idna_to_unicode_8z4z (p, &r, 0); free (p); if (rc != IDNA_SUCCESS) { printf ("idna_to_unicode_8z4z failed (%d): %s\n", rc, idna_strerror (rc)); return 2; } printf ("ToUnicode string: "); for (i = 0; r[i]; i++) printf ("U+%04x ", r[i]); printf ("\n"); rc = tld_check_4z (r, &errpos, NULL); free (r); if (rc == TLD_INVALID) { printf ("Domain rejected by TLD check, Unicode position %ld\n", (long int) errpos); return 1; } else if (rc != TLD_SUCCESS) { printf ("tld_check_4z() failed (%d): %s\n", rc, tld_strerror (rc)); return 2; } printf ("Domain accepted by TLD check\n"); return 0; }