[j-nsp] Control giaddr in forwarded bootp/dhcp request?

[Phil Mayers]

We have a remote router (SRX210 in packet mode running 11.2) with a 
private and public IP range on the same interface:

unit 0 {
     family inet {
         filter {
             input MH-OUT-FILTER;
         }
         address 212.x.x.1/25 {
             preferred;
         }
         address 212.x.x.129/26;
         address 192.168.5.1/25;
     }
}

When I enable bootp forwarding:

forwarding-options {
     helpers {
         bootp {
             interface {
                 ge-0/0/1.0 {
                     server a.b.c.d;
                 }
             }
         }
     }
}

...the bootp packets arrive with an outer IP as per normal unicast 
routing, but a "giaddr" field of 192.168.5.1, even though I've set 
212.x.x.1 as the "preferred" IP.

This causes problems, because the DHCP server can't directly reach 
192.168.5.0/24 from its location.

Can I control the "giaddr" field in a forwarded bootp request on JunOS?

Cheers,
Phil