Topic: XPath confusion

All righty, I've worked with XPaths before, but it's been mostly trivial stuff, simple queries to return a single node based on various conditions (and all in C# before).

I'm working on something a little more complicated now (and in C++ using libxml2), and I'm getting results that are making my head hurt. I need to pull out a node (and all its children and contents) and canonicalize it.

I've got the following XML (not the complete doc, but enough for this example):

<S:Envelope xmlns:S="http://schemas.xmlsoap.org/soap/envelope/">
   <S:Header>
      <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd">
         <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
            <ds:SignedInfo>
		   <ds:subnode>blah</ds:subnode>
            </ds:SignedInfo>
         </ds:Signature>
      </wsse:Security>
   </S:Header>
   <S:Body wsu:Id="Body-1-2cb7c7df3ee732dfa7f9a020ad2a5cd6" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
   </S:Body>
</S:Envelope>

Using this XPath: (//. | //@* | //namespace::*)[ancestor-or-self::ds:SignedInfo]

If I iterate through the nodeset returned from the xpath query, I get the following:

returned: 11 nodes

Node: SignedInfo

Node: subnode

Node: text

Node: http://www.w3.org/XML/1998/namespace

Node: http://schemas.xmlsoap.org/soap/envelope/

Node: http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd

Node: http://www.w3.org/2000/09/xmldsig#

Node: http://www.w3.org/XML/1998/namespace

Node: http://schemas.xmlsoap.org/soap/envelope/

Node: http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd

Node: http://www.w3.org/2000/09/xmldsig#

Am I missing something in the XPath? Is //namespace::* not filtered by "ancestor-or-self::ds:SignedInfo"?

I think I have a solution that works, but I'd still like to understand what's going on a little better.

LF

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Any sufficiently advanced bug is indistinguishable from a feature.