code review 12332043: syscall: fix IPv6 wrong network mask on latest FreeBSD

src/pkg/syscall/route_bsd.go

 // Copyright 2011 The Go Authors.  All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // +build darwin freebsd netbsd openbsd
 
 // Routing sockets and messages
 
 package syscall
 
@@ skipping 138 matching lines @@
                 rsa := (*RawSockaddr)(unsafe.Pointer(&b[0]))
                 switch i {
                 case RTAX_IFA:
                         sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(rsa)))
                         if err != nil {
                                 return nil
                         }
                         sas = append(sas, sa)
                 case RTAX_NETMASK:
                         if rsa.Family == AF_UNSPEC {
-                                rsa.Family = AF_INET // an old fasion, AF_UNSPEC means AF_INET
+                                switch rsa.Len {
+                                case SizeofSockaddrInet4:
+                                        rsa.Family = AF_INET
+                                case SizeofSockaddrInet6:
+                                        rsa.Family = AF_INET6
+                                default:
+                                        rsa.Family = AF_INET // an old fasion, AF_UNSPEC means AF_INET
+                                }
                         }
                         sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(rsa)))
                         if err != nil {
                                 return nil
                         }
                         sas = append(sas, sa)
                 case RTAX_BRD:
                         // nothing to do
                 }
                 b = b[rsaAlignOf(int(rsa.Len)):]
@@ skipping 13 matching lines @@
                 b = b[any.Msglen:]
         }
         return msgs, nil
 }
 
 // ParseRoutingMessage parses msg's payload as raw sockaddrs and
 // returns the slice containing the Sockaddr interfaces.
 func ParseRoutingSockaddr(msg RoutingMessage) (sas []Sockaddr, err error) {
         return append(sas, msg.sockaddr()...), nil
 }