Detect source datastream version

Instead of hard-coding SCAP 1.2, we will use
data-stream-collection@schematron-version attribute to detect the SCAP
version of datastream and we will choose the right XML schema
accordingly. So far, only 1.2 and 1.3 datastreams are supported.

Author: jan-cerny

src/DS/sds.c

@@ -1233,3 +1233,29 @@ int ds_sds_compose_from_xccdf(const char *xccdf_file, const char *target_datastr
 	xmlFreeDoc(doc);
 	return 0;
 }
+
+char *ds_sds_detect_version(xmlTextReader *reader)
+{
+	/* find root element */
+	while (xmlTextReaderRead(reader) == 1 && xmlTextReaderNodeType(reader) != XML_READER_TYPE_ELEMENT)
+		;
+
+	char *element_name = (char *) xmlTextReaderConstLocalName(reader);
+	if (!element_name) {
+		oscap_setxmlerr(xmlGetLastError());
+		return NULL;
+	}
+	if (strcmp(element_name, "data-stream-collection")) {
+		oscap_seterr(OSCAP_EFAMILY_OSCAP,
+			"Expected root element name for SCAP source datastream is" \
+			"'data-stream-collection' but actual root element name is '%s'.",
+			element_name);
+		return NULL;
+	}
+	char *schematron_version = (char *) xmlTextReaderGetAttribute(reader, BAD_CAST "schematron-version");
+	if (!schematron_version) {
+		oscap_setxmlerr(xmlGetLastError());
+		return NULL;
+	}
+	return schematron_version;
+}

src/DS/sds_priv.h

@@ -26,6 +26,7 @@
 #endif
 
 #include <libxml/tree.h>
+#include <libxml/xmlreader.h>
 #include "common/public/oscap.h"
 #include "common/util.h"
 #include "ds_sds_session.h"
@@ -49,4 +50,6 @@ xmlNodePtr ds_sds_find_component_ref(xmlNodePtr datastream, const char *id);
 
 char *ds_sds_mangle_filepath(const char *filepath);
 
+char *ds_sds_detect_version(xmlTextReader *reader);
+
 #endif

src/source/oscap_source.c

@@ -363,7 +363,7 @@ const char *oscap_source_get_schema_version(struct oscap_source *source)
 		}
 		switch (oscap_source_get_scap_type(source)) {
 			case OSCAP_DOCUMENT_SDS:
-				source->origin.version = oscap_strdup("1.2");
+				source->origin.version = ds_sds_detect_version(reader);
 				break;
 			case OSCAP_DOCUMENT_ARF:
 				source->origin.version = oscap_strdup("1.1");

src/source/validate.c

@@ -225,6 +225,7 @@ struct oscap_schema_table_entry OSCAP_SCHEMAS_TABLE[] = {
 	{OSCAP_DOCUMENT_XCCDF_TAILORING,	"1.2",	"xccdf/1.2/xccdf_1.2.xsd"},
 	{OSCAP_DOCUMENT_XCCDF_TAILORING,	"1.1",	"xccdf/1.1-tailoring/xccdf-1.1-tailoring.xsd"}, // unofficial openscap extension!
 	{OSCAP_DOCUMENT_SDS,                "1.2",  "sds/1.2/scap-source-data-stream_1.2.xsd"},
+	{OSCAP_DOCUMENT_SDS,                "1.3",  "sds/1.3/scap-source-data-stream_1.3.xsd"},
 	{OSCAP_DOCUMENT_ARF,                "1.1",  "arf/1.1/asset-reporting-format_1.1.0.xsd"},
 	{OSCAP_DOCUMENT_CPE_DICTIONARY,		"2.0", "cpe/2.0/cpe-dictionary_2.0.xsd"},
 	{OSCAP_DOCUMENT_CPE_DICTIONARY,		"2.1", "cpe/2.1/cpe-dictionary_2.1.xsd"},