Re: [xml] C14N does not handle empty-namespace declarations as the implementation in Java

[Aleksey Sanin <aleksey aleksey com>]

Yes, namespace nodes are *nodes* and all the usual rules apply.

Aleksey

Arne Müller wrote:
> Hi Aleksey,
>
> thanks for pointing me to those test-files. With them I also do not get 
> xmlns="".
> So then I checked, where there were differences between my code and the 
> one in testC14N.c.
> I realized, that the xmlns="" appears, because I use a nodeset.
> It seems, if I use a default namespace, I have to add for each 
> descandant a copy of it into the NodeSet, else it will not find it and 
> will not set, that it has found a default-namespace.
> (see line 623 in c14n.c)
> Is this the intended behavior? I thought it would be sufficient to add 
> the namespace for the namespace-declaring node into the nodeset and not 
> for all descendant nodes.
>
> Somehow the example code does this correctly (when given the XPath 
> "/descendant::* | /descendant::*/attribute::* | 
> /descendant::*/namespace::*").
>
> So XPath seems to add namespace declarations everywhere and thus avoid 
> the problem, while I have build the nodeset myself and not added as many 
> namespace declarations (which I actually think create very much overhead).
>
> I think I could now avoid the problem by modifying my NodeSet-creation 
> code, to make it add namespaces for all descendants into the nodeset.
> But maybe it would be better non the less to simply check if the nodeset 
> contains a namespace-declaration for a parent node? Or am I missing 
> something?
>
> Arne
>
>
> 2008/8/26 Aleksey Sanin <aleksey aleksey com <mailto:aleksey aleksey com>>
>
>     Arne,
>
>     Could you please give an exact example that shows the problem
>     using the testC14N command? For example, for the xml snippet
>     from your previous email I generated C14N and I see no xmlns=""
>     definitions:
>
>     $ testC14N --with-comments test.xml > test-c14n.xml
>
>     Thanks
>     Aleksey
>
>
>     Arne Mueller wrote:
>
>         Am Sonntag, den 24.08.2008, 21:21 -0700 schrieb Aleksey Sanin:
>
>             Hi, Arne!
>
>             Sorry, but as I have replied in xmlsec mailing list, I believe
>             that libxml2 is doing the right thing here.
>
>             Aleksey
>
>
>         Hi Aleksey,
>         you might be perfectly right with adding one empty namespace.
>
>         But I think one thing is buggy non the less, in the
>         c14n-specification
>         it says:
>
>         <quote>
>         4.6 Superfluous Namespace Declarations
>         Unnecessary namespace declarations are not made in the canonical
>         form.
>         Whether for an empty default namespace, a non-empty default
>         namespace,
>         or a namespace prefix binding, the XML canonicalization method
>         omits a
>         declaration if it determines that the immediate parent element
>         in the
>         canonical form has an equivalent declaration in scope. The root
>         document
>         element is handled specially since it has no parent element. All
>         namespace declarations in it are retained, except the
>         declaration of an
>         empty default namespace is automatically omitted.
>         </quote>
>
>         Thus, there should be at most one empty namespace declaration,
>         because
>         an parent element has already defined the empty namespace
>         declaration.
>         The same holds for the redefinition of "dsig" in the XPath element.
>
>         Arne