fix: libxml2 related deprecated issues in v3

[airween]

Similar as #3454 for v2.

what

This PR fixes libxml2 related deprecated warnings.

why

With newest clang and gcc compilers and newest libxml2 library there were a few deprecated warnings.

In file included from ../src/request_body_processor/xml.h:19,
                 from transaction.cc:40:
/usr/include/libxml2/libxml/SAX.h:15:4: warning: #warning "libxml/SAX.h is deprecated" [-Wcpp]
   15 |   #warning "libxml/SAX.h is deprecated"
      |    ^~~~~~~

operators/validate_dtd.cc: In member function 'virtual bool modsecurity::operators::ValidateDTD::init(const std::string&, std::string*)':
operators/validate_dtd.cc:36:33: warning: 'void xmlThrDefSetGenericErrorFunc(void*, xmlGenericErrorFunc)' is deprecated [-Wdeprecated-declarations]
   36 |     xmlThrDefSetGenericErrorFunc(NULL,
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
   37 |         null_error);
      |         ~~~~~~~~~~~              

operators/validate_schema.cc: In member function 'virtual bool modsecurity::operators::ValidateSchema::evaluate(modsecurity::Transaction*, const std::string&)':
operators/validate_schema.cc:74:33: warning: 'void xmlThrDefSetGenericErrorFunc(void*, xmlGenericErrorFunc)' is deprecated [-Wdeprecated-declarations]
   74 |     xmlThrDefSetGenericErrorFunc(parserCtx,
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
   75 |         null_error);
      |         ~~~~~~~~~~~              

I removed not just xmlThrDefSetGenericErrorFunc() call but the xmlSetGenericErrorFunc() too, because in libxml2 documentation both functions are marked as deprecated.

Beside of that, all error handlers are set to a null_error() function which did nothing, so I remove those handlers too, and set the contexts' options to XML_PARSE_NOWARNING | XML_PARSE_NOERROR as libxml2's documentation recommends that.

references

• deprecated function xmlThrDefSetGenericErrorFunc()
• deprecated function xmlSetStructuredErrorFunc()
• both description mention
  "If you only want to disable parser errors being printed to stderr, use xmlParserOption XML_PARSE_NOERROR"

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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