Simplify idn_locale_to_ace()

idn_locale_to_ace() is a static function which is always used with a
buffer of size MXNAME, i.e. one that can fit any valid domain name.
Since libidn2 detects invalid domain names and libidn2 errors are
considered fatal, remove size checks from idn_locale_to_ace().  This
makes returning an isc_result_t from it unnecessary.

Do not process success cases in conditional branches for improved
consistency with the rest of BIND source code.  Add a comment explaining
the purpose of idn_locale_to_ace().  Rename that function's parameters
to match common BIND naming pattern.

diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index 6d0c9b86e2ee7f030843a416883730b5e2795084..30c3e109e8b8b03ce6d7895bd11a4660ef3bcf82 100644 (file)
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -133,9 +133,7 @@ int lookup_counter = 0;
 static char servercookie[256];
 
 #ifdef HAVE_LIBIDN2
-static isc_result_t idn_locale_to_ace(const char *from,
-               char *to,
-               size_t tolen);
+static void idn_locale_to_ace(const char *src, char *dst, size_t dstlen);
 static isc_result_t idn_ace_to_locale(const char *from,
                char *to,
                size_t tolen);
@@ -2055,8 +2053,7 @@ setup_lookup(dig_lookup_t *lookup) {
        textname = lookup->textname;
 #ifdef HAVE_LIBIDN2
        if (lookup->idnin) {
-               result = idn_locale_to_ace(textname, idn_textname, sizeof(idn_textname));
-               check_result(result, "convert textname to IDN encoding");
+               idn_locale_to_ace(textname, idn_textname, sizeof(idn_textname));
                debug("idn_textname: %s", idn_textname);
                textname = idn_textname;
        }
@@ -2091,8 +2088,8 @@ setup_lookup(dig_lookup_t *lookup) {
                origin = lookup->origin->origin;
 #ifdef HAVE_LIBIDN2
                if (lookup->idnin) {
-                       result = idn_locale_to_ace(origin, idn_origin, sizeof(idn_origin));
-                       check_result(result, "convert origin to IDN encoding");
+                       idn_locale_to_ace(origin, idn_origin,
+                                         sizeof(idn_origin));
                        debug("trying idn origin %s", idn_origin);
                        origin = idn_origin;
                }
@@ -4252,43 +4249,40 @@ output_filter(isc_buffer_t *buffer, unsigned int used_org,
        return (ISC_R_SUCCESS);
 }
 
-static isc_result_t
-idn_locale_to_ace(const char *from, char *to, size_t tolen) {
+/*%
+ * Convert 'src', which is a string using the current locale's character
+ * encoding, into an ACE string suitable for use in the DNS, storing the
+ * conversion result in 'dst', which is 'dstlen' bytes large.
+ *
+ * 'dst' MUST be large enough to hold any valid domain name.
+ */
+static void
+idn_locale_to_ace(const char *src, char *dst, size_t dstlen) {
+       const char *final_src;
+       char *ascii_src;
        int res;
-       char *tmp_str = NULL;
 
-       res = idn2_to_ascii_lz(from, &tmp_str, IDN2_NONTRANSITIONAL|IDN2_NFC_INPUT);
-       if (res == IDN2_OK) {
-               /*
-                * idn2_to_ascii_lz() normalizes all strings to lowerl case,
-                * but we generally don't want to lowercase all input strings;
-                * make sure to return the original case if the two strings
-                * differ only in case
-                */
-               if (!strcasecmp(from, tmp_str)) {
-                       if (strlen(from) >= tolen) {
-                               debug("from string is too long");
-                               idn2_free(tmp_str);
-                               return ISC_R_NOSPACE;
-                       }
-                       idn2_free(tmp_str);
-                       (void) strlcpy(to, from, tolen);
-                       return ISC_R_SUCCESS;
-               }
-               /* check the length */
-               if (strlen(tmp_str) >= tolen) {
-                       debug("ACE string is too long");
-                       idn2_free(tmp_str);
-                       return ISC_R_NOSPACE;
-               }
-
-               (void) strlcpy(to, tmp_str, tolen);
-               idn2_free(tmp_str);
-               return ISC_R_SUCCESS;
+       /*
+        * We trust libidn2 to return an error if 'src' is too large to be a
+        * valid domain name.
+        */
+       res = idn2_to_ascii_lz(src, &ascii_src,
+                              IDN2_NFC_INPUT | IDN2_NONTRANSITIONAL);
+       if (res != IDN2_OK) {
+               fatal("'%s' is not a legal IDNA2008 name (%s), use +noidnin",
+                     src, idn2_strerror(res));
        }
 
-       fatal("'%s' is not a legal IDNA2008 name (%s), use +noidnin", from, idn2_strerror(res));
-       return ISC_R_FAILURE;
+       /*
+        * idn2_to_ascii_lz() normalizes all strings to lower case, but we
+        * generally don't want to lowercase all input strings; make sure to
+        * return the original case if the two strings differ only in case.
+        */
+       final_src = (strcasecmp(src, ascii_src) == 0 ? src : ascii_src);
+
+       (void)strlcpy(dst, final_src, dstlen);
+
+       idn2_free(ascii_src);
 }
 
 static isc_result_t