Refuse to resolve some types of invalid DNS addresses.

net/dns/dns_util.h

Index: net/dns/dns_util.h
diff --git a/net/dns/dns_util.h b/net/dns/dns_util.h
index 470242c0cedc11992558c76989d1445ba1e0f8fe..c81ffde34ada56f1957aeebe345f6733eb3ee025 100644
--- a/net/dns/dns_util.h
+++ b/net/dns/dns_util.h
@@ -24,6 +24,9 @@ class AddressList;
 NET_EXPORT_PRIVATE bool DNSDomainFromDot(const base::StringPiece& dotted,
                                          std::string* out);
 
+// Checks that a hostname is valid. Simple wrapper around DNSDomainFromDot.
+NET_EXPORT_PRIVATE bool IsValidDNSDomain(const base::StringPiece& dotted);
+
 // DNSDomainToString converts a domain in DNS format to a dotted string.
 // Excludes the dot at the end.
 NET_EXPORT_PRIVATE std::string DNSDomainToString(