7819 IPv6 Packet and MTU bug

*** 21,31 ****
  
  /*
   * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 1990 Mentat Inc.
   * Copyright (c) 2012 Joyent, Inc. All rights reserved.
!  * Copyright (c) 2014, OmniTI Computer Consulting, Inc. All rights reserved.
   */
  
  #include <sys/types.h>
  #include <sys/stream.h>
  #include <sys/dlpi.h>
--- 21,31 ----
  
  /*
   * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 1990 Mentat Inc.
   * Copyright (c) 2012 Joyent, Inc. All rights reserved.
!  * Copyright (c) 2017 OmniTI Computer Consulting, Inc. All rights reserved.
   */
  
  #include <sys/types.h>
  #include <sys/stream.h>
  #include <sys/dlpi.h>
*** 3856,3869 ****
                                  pmtu = IPV6_MIN_MTU;
                  }
          }
  
          /*
!          * After receiving an ICMPv6 "packet too big" message with a
!          * MTU < 1280, and for multirouted IPv6 packets, the IP layer
!          * will insert a 8-byte fragment header in every packet. We compensate
!          * for those cases by returning a smaller path MTU to the ULP.
           *
           * In the case of CGTP then ip_output will add a fragment header.
           * Make sure there is room for it by telling a smaller number
           * to the transport.
           *
--- 3856,3868 ----
                                  pmtu = IPV6_MIN_MTU;
                  }
          }
  
          /*
!          * For multirouted IPv6 packets, the IP layer will insert a 8-byte
!          * fragment header in every packet. We compensate for those cases by
!          * returning a smaller path MTU to the ULP.
           *
           * In the case of CGTP then ip_output will add a fragment header.
           * Make sure there is room for it by telling a smaller number
           * to the transport.
           *
*** 3870,3881 ****
           * When IXAF_IPV6_ADDR_FRAGHDR we subtract the frag hdr here
           * so the ULPs consistently see a iulp_pmtu and ip_get_pmtu()
           * which is the size of the packets it can send.
           */
          if (!(ixa->ixa_flags & IXAF_IS_IPV4)) {
!                 if ((dce->dce_flags & DCEF_TOO_SMALL_PMTU) ||
!                     (ire->ire_flags & RTF_MULTIRT) ||
                      (ixa->ixa_flags & IXAF_MULTIRT_MULTICAST)) {
                          pmtu -= sizeof (ip6_frag_t);
                          ixa->ixa_flags |= IXAF_IPV6_ADD_FRAGHDR;
                  }
          }
--- 3869,3879 ----
           * When IXAF_IPV6_ADDR_FRAGHDR we subtract the frag hdr here
           * so the ULPs consistently see a iulp_pmtu and ip_get_pmtu()
           * which is the size of the packets it can send.
           */
          if (!(ixa->ixa_flags & IXAF_IS_IPV4)) {
!                 if ((ire->ire_flags & RTF_MULTIRT) ||
                      (ixa->ixa_flags & IXAF_MULTIRT_MULTICAST)) {
                          pmtu -= sizeof (ip6_frag_t);
                          ixa->ixa_flags |= IXAF_IPV6_ADD_FRAGHDR;
                  }
          }