Handle hardened XML checks with path API

IB-8939

Signed-off-by: Raul Metsma <raul@metsma.ee>

Author: metsma

src/XMLDocument.h

@@ -34,6 +34,7 @@
 
 #include <openssl/evp.h>
 
+#include <fstream>
 #include <istream>
 
 namespace digidoc {
@@ -308,9 +309,13 @@ struct XMLDocument: public unique_free_d<xmlFreeDoc>, public XMLNode
             d = {};
     }
 
-    XMLDocument(const std::string &path, const XMLName &n = {}) noexcept
-        : XMLDocument(path.empty() ? nullptr : xmlParseFile(path.c_str()), n)
-    {}
+    XMLDocument(const std::string &path, const XMLName &n = {})
+    {
+        if(path.empty())
+            return;
+        if(std::ifstream f{path})
+            *this = openStream(f, n);
+    }
 
     template <typename F>
     static XMLDocument open(F &&f, const XMLName &name = {}, bool hugeFile = false)

src/XmlConf.cpp

@@ -124,7 +124,9 @@ XmlConf::Private::Private(Conf *self, const string &path, string schema)
 auto XmlConf::Private::loadDoc(const string &path) const
 {
     LIBXML_TEST_VERSION
-    auto doc = XMLDocument(path, {"configuration"});
+    XMLDocument doc;
+    try { doc = XMLDocument(path, {"configuration"}); }
+    catch(const Exception &) {}
     if(!doc)
     {
         WARN("Failed to parse configuration: %s", path.c_str());

test/libdigidocpp_boost.cpp

@@ -605,8 +605,8 @@ BOOST_AUTO_TEST_SUITE_END()
 BOOST_AUTO_TEST_SUITE(XMLTestSuite)
 BOOST_AUTO_TEST_CASE(XMLBomb)
 {
-    BOOST_CHECK_EQUAL(XMLDocument("xml-bomb-attr.xml"), false);
-    BOOST_CHECK_EQUAL(XMLDocument("xml-bomb-cont.xml"), false);
+    BOOST_CHECK_THROW(XMLDocument("xml-bomb-attr.xml"), Exception);
+    BOOST_CHECK_THROW(XMLDocument("xml-bomb-cont.xml"), Exception);
     if(std::fstream f{"xml-bomb-attr.xml"})
         BOOST_CHECK_THROW(XMLDocument::openStream(f), Exception);
     if(std::fstream f{"xml-bomb-cont.xml"})
@@ -655,6 +655,7 @@ BOOST_AUTO_TEST_CASE(XMLXXE)
         "]><root>&sentinel;</root>",
     };
 
+    size_t payloadIndex = 0;
     for(const auto &payload : payloads) {
         for(bool huge : {false, true}) {
             std::istringstream is{std::string(payload)};
@@ -664,6 +665,21 @@ BOOST_AUTO_TEST_CASE(XMLXXE)
             BOOST_CHECK(!text.contains("XXESENTINEL"));
             xmlFree(raw);
         }
+
+        const auto path = (fs::temp_directory_path() /
+            ("libdigidocpp-xxe-payload-" + std::to_string(payloadIndex++) + ".xml")).string();
+        std::ofstream out{path, std::ofstream::binary};
+        BOOST_REQUIRE(out.is_open());
+        out << payload;
+        out.close();
+        BOOST_REQUIRE(out.good());
+
+        auto doc = XMLDocument(path);
+        xmlChar *raw = xmlNodeGetContent(doc.d);
+        std::string_view text = raw ? (const char*)raw : "";
+        BOOST_CHECK(!text.contains("XXESENTINEL"));
+        xmlFree(raw);
+        fs::remove(path);
     }
 }
 BOOST_AUTO_TEST_SUITE_END()