Don't assert() that labels must be < 32 chars

Labels can be up to 63 chars. If a longer label is encountered, we exit
cleanly instead of asserting (since it's an environment/invocation
issue, not an internal consistency issue).

Fixes VAS bug #23009.

CHANGES

@@ -1,3 +1,5 @@
+1.3.5 [2011-02-03]
+    - Don't crash on labels longer than 32 characters (VAS bug #23009)
 
 1.3.4 [2010-06-10]
     - bug 763: Symbol not found: _vas_log_init, when using QAS 4.0

configure.ac

@@ -1,7 +1,7 @@
 # (c) 2006 Quest Software, Inc. All rights reserved.
 
 AC_INIT([dnsupdate],
-	[1.3.4.]esyscmd(svnversion -n . /trunk || echo 0),
+	[1.3.5.]esyscmd(svnversion -n . /trunk || echo 0),
 	[[email protected]])
 AM_INIT_AUTOMAKE
 AC_CONFIG_SRCDIR([dnsupdate.c])

dns.c

@@ -459,7 +459,10 @@ wr_label(struct dns_msg *msg, int len, const char *name)
 {
     unsigned char b;
 
-    assert(len < 32);
+    if (len > 63)
+        errx(1, "Refusing to write label \"%s\" "
+                "which is longer than 63 characters", name);
+
     b = (unsigned char)len;
     dns_wr_data_raw(msg, &b, sizeof b);
     if (len)