9832 Original bug discovered as 9560 has friends IPv4 packets coming in as IPv6 creating chaos

*** 18,27 ****
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright 2018 Joyent, Inc.
   */
  
  /*
   * MAC Services Module - misc utilities
   */
*** 489,499 ****
          ip6_rthdr_t *rthdr;
          ip6_frag_t *fraghdr;
  
          if (((uchar_t *)ip6h + IPV6_HDR_LEN) > endptr)
                  return (B_FALSE);
!         ASSERT(IPH_HDR_VERSION(ip6h) == IPV6_VERSION);
          length = IPV6_HDR_LEN;
          whereptr = ((uint8_t *)&ip6h[1]); /* point to next hdr */
  
          if (fragp != NULL)
                  *fragp = NULL;
--- 490,507 ----
          ip6_rthdr_t *rthdr;
          ip6_frag_t *fraghdr;
  
          if (((uchar_t *)ip6h + IPV6_HDR_LEN) > endptr)
                  return (B_FALSE);
!         /*
!          * NOTE: Version-check failure here may cause mismatched IP versions
!          * to propagate ENOBUFS in some callers, instead of letting the
!          * packet reach the appropriate IP input function, where version check
!          * errors are logged & counted.
!          */
!         if (IPH_HDR_VERSION(ip6h) != IPV6_VERSION)
!                 return (B_FALSE);
          length = IPV6_HDR_LEN;
          whereptr = ((uint8_t *)&ip6h[1]); /* point to next hdr */
  
          if (fragp != NULL)
                  *fragp = NULL;