+#if defined(PHP_WIN32) || defined(HAVE_UIDNA_IDNTOASCII)
+typedef size_t (*parse_mb_func)(unsigned *wc, const char *ptr, const char *end);
+static STATUS to_utf16(parse_mb_func fn, const char *u8, uint16_t **u16, size_t *len)
+{
+ size_t offset = 0, u8_len = strlen(u8);
+
+ *u16 = ecalloc(4 * sizeof(uint16_t), u8_len + 1);
+ *len = 0;
+
+ while (offset < u8_len) {
+ unsigned wc;
+ uint16_t buf[2], *ptr = buf;
+ size_t consumed = fn(&wc, &u8[offset], &u8[u8_len]);
+
+ if (!consumed) {
+ efree(*u16);
+ php_error_docref(NULL TSRMLS_CC, E_WARNING, "Failed to parse UTF-8 at pos %zu of '%s'", offset, u8);
+ return FAILURE;
+ } else {
+ offset += consumed;
+ }
+
+ switch (wctoutf16(buf, wc)) {
+ case 2:
+ (*u16)[(*len)++] = *ptr++;
+ /* no break */
+ case 1:
+ (*u16)[(*len)++] = *ptr++;
+ break;
+ case 0:
+ default:
+ efree(*u16);
+ php_error_docref(NULL TSRMLS_CC, E_WARNING, "Failed to convert UTF-32 'U+%X' to UTF-16", wc);
+ return FAILURE;
+ }
+ }
+
+ return SUCCESS;
+}
+#endif
+
+#ifndef MAXHOSTNAMELEN
+# define MAXHOSTNAMELEN 256
+#endif
+