change valid_domainname() to accept a trailing dot.

ok millert@

diff --git a/usr.sbin/smtpd/util.c b/usr.sbin/smtpd/util.c
index 1ff713b..fff0f77 100644 (file)
--- a/usr.sbin/smtpd/util.c
+++ b/usr.sbin/smtpd/util.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: util.c,v 1.146 2019/08/23 12:09:41 eric Exp $ */
+/*     $OpenBSD: util.c,v 1.147 2019/08/28 19:46:20 eric Exp $ */
 
 /*
  * Copyright (c) 2000,2001 Markus Friedl.  All rights reserved.
@@ -548,40 +548,44 @@ valid_domainpart(const char *s)
        return res_hnok(s);
 }
 
-#define charok(c) ((c) == '-' || (c) == '_' || isalpha((int)(c)) || isdigit((int)(c)))
-
-#define MAXLABELSIZE 64
-#define MAXDNAMESIZE 254
+#define LABELCHR(c) ((c) == '-' || (c) == '_' || isalpha((int)(c)) || isdigit((int)(c)))
+#define LABELMAX 63
+#define DNAMEMAX 253
 
 int
-valid_domainname(const char *dname)
+valid_domainname(const char *str)
 {
-       const char *label, *s = dname;
+       const char *label, *s;
 
-       /* read a sequence of dot-separated label */
-       for (;;) {
+       /*
+        * Expect a sequence of dot-separated labels, possibly with a trailing
+        * dot. The empty string is rejected, as well a single dot.
+        */
+       for (s = str; *s; s++) {
 
-               /* label must have at least one char */
-               if (!charok(*s))
-                       return 0;
+               /* Start of a new label. */
                label = s;
-               s++;
-
-               /* read all chars */
-               while (charok(*s))
+               while (LABELCHR(*s))
                        s++;
-               if (s - label >= MAXLABELSIZE)
+
+               /* Must have at least one char and at most LABELMAX. */
+               if (s == label || s - label > LABELMAX)
                        return 0;
 
-               if (*s == '\0') {
-                       if (s - dname >= MAXDNAMESIZE)
-                               return 0;
-                       return 1;
-               }
+               /* If last label, stop here. */
+               if (*s == '\0')
+                       break;
+
+               /* Expect a dot as label separator or last char. */
                if (*s != '.')
                        return 0;
-               s++;
        }
+
+       /* Must have at leat one label and no more than DNAMEMAX chars. */
+       if (s == str || s - str > DNAMEMAX)
+               return 0;
+
+       return 1;
 }
 
 int