pickling / unpickling self-relative (was: Re: Quick question on IDL)

[Luke Kenneth Casson Leighton]

On Tue, Oct 16, 2001 at 01:56:39PM -0400, Tatsukawa, Seiichi wrote:
> > just took a look at it, compiled up the encoding example,
> > i notice that it sends the idl UUID at the beginning,
> > plus the idl version number etc.
> > 
> > here is an example that i wish to encode / decode.
> > 
> > note that it doesn't have an idl UUID at the front:
> > i can live with that, by faking up the UUID at the
> > front of the buffer, and doing anything else necessary.
> 
> idl_es_pvt_header_t is defined in sys_idl/idlddefs.h .
 
excellent!  thanks.  gives the length if nothing else.

> > the nasty bit about this example is the pointers.
> > note at offsets 0014 and 001c indicating self-relative
> > offsets to 0x20 and 0x29.
> 
> I think that I already answered this when you are looking at pickling
> Security Descriptors. The self-relative Security Descriptor is NOT
> NDR-encoded stream. 

having written a hand-marshalling/unmarshalling api,
prs_secdes.c, i am fairly confident that the self-relative
SD can be said to be "ms" NDR-encoded, as long as you
do these  "self-relative pointers"

the decision as to whether to treat a security descriptor
LPVOID* as self-relative or non-self-relative is taken
by checking the second set of 2 bytes: bit
SEC_DESC_SELF_RELATIVE (0x800).

if clear, i am hoping to unmarshall, if set, just
leave as-is.


> It can't be expressed by the IDL file. So, some
> structures probably need to be hand-un/marshalled.

i sincerely hope that it can, and want to 'ave a go at it.


> 
> P.S.
> Well, the layout of auth_verifier could be NDR-encoded by using the nested
> structures. (See "Algorithm for Deferral of Referents" in NDR spec., part of
> OpenGroup's "DCE 1.1: Remote Procedure Call " Spec.) However, if I remember
> correctly, OSF DCE IDL's NDR-encoder uses the sequentially incremented
> referent identifier (starting from 1). Since the referent identifier is an
> unsigned long integer (non-zero, uniquely defined within output NDR stream),
> you can replace it with the byte offset within the output stream.


rpc_ss_register_node() is the "key" point that generates a link
between referent identifiers and the on-wire structure.

what i am hoping to do is do as you suggest on a _second_ pass,
using rpc_ss_register_node() to record the necessary information:
the address of the byte offset in the output stream for every
referent identifier, and replace with byte offset, also recorded
in the node table.

luke