XML AddressSpace parser fails on Empty ExtendedObject Body subNodes

Description

The XML AddressSpace parsing (sopc_uanodeset_loader.c file) does not apply the same rules for non-defined ExtendedObject Body subNodes and for empty ones (Eg for EURange):

• uax:Range</uax:Range> is accepted and uses the default value for Low and high (0.0)
• uax:Range<uax:Low /></uax:Range> fails (with no real explicit message, except for ExtendedObject block line in source XML file, making the issue obscure for user)

Code version and environment identification

e2febefcc11936f1f4cfadfdb664bed58795c8b3 (1.6.0*)

Steps to reproduce

Use this configuraiton:

  <UAVariable NodeId="s=A_EURange" BrowseName="EURange" DataType="i=884">
    <DisplayName>EURange</DisplayName>
    <Description>EURange</Description>
    <References>
      <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
    </References>
    <Value>
      <uax:ListOfExtensionObject>
        <uax:ExtensionObject>
          <uax:TypeId>
            <uax:Identifier>i=884</uax:Identifier>
          </uax:TypeId>
          <uax:Body>
            <uax:Range>
              <uax:Low />
              <uax:High></uax:High>
            </uax:Range>
          </uax:Body>
        </uax:ExtensionObject>
      </uax:ListOfExtensionObject>
    </Value>
  </UAVariable>

Analysis

In sopc_uanodeset_loader.c: see functions set_variant_value_extobj_range and similars on ExtensionObject Value parsing.

• When returning false, no context is provided
• if (result && highTagCtx->set) implies a difference between unset tags and undefined tags.

Security impact

None (Software won't start)

Possible fixes

• Add context for each problem in all ExtendedObjects parserse
• Replace by if (result && highTagCtx->set && (*highTagCtx->single_value) != 0) (for example) in all reads where the interpretation of the content may fail for an empty node (relying on SOPC_strtodoubleand SOPC_strtoint)

Note : this only applies to Extended Object parsing (it is not expected that an empty NodeId could work)