Don't ignore errors parsing nwfilter rules

For inexplicable reasons, the nwfilter XML parser is intentionally
ignoring errors that arise during parsing. As well as meaning that
users don't get any feedback on their XML mistakes, this will lead
it to silently drop data in OOM conditions.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 4f209434)

src/conf/nwfilter_conf.c

@@ -2375,9 +2375,7 @@ virNWFilterRuleParse(xmlNodePtr node)
                     if (virNWFilterRuleDetailsParse(cur,
                                                     ret,
                                                     virAttr[i].att) < 0) {
-                        /* we ignore malformed rules
-                           goto err_exit;
-                        */
+                        goto err_exit;
                     }
                     break;
                 }
@@ -2582,11 +2580,13 @@ virNWFilterDefParseXML(xmlXPathContextPtr ctxt) {
                 goto cleanup;
             }
 
-            /* ignore malformed rule and include elements */
-            if (xmlStrEqual(curr->name, BAD_CAST "rule"))
-                entry->rule = virNWFilterRuleParse(curr);
-            else if (xmlStrEqual(curr->name, BAD_CAST "filterref"))
-                entry->include = virNWFilterIncludeParse(curr);
+            if (xmlStrEqual(curr->name, BAD_CAST "rule")) {
+                if (!(entry->rule = virNWFilterRuleParse(curr)))
+                    goto cleanup;
+            } else if (xmlStrEqual(curr->name, BAD_CAST "filterref")) {
+                if (!(entry->include = virNWFilterIncludeParse(curr)))
+                    goto cleanup;
+            }
 
             if (entry->rule || entry->include) {
                 if (VIR_REALLOC_N(ret->filterEntries, ret->nentries+1) < 0) {

tests/nwfilterxml2xmltest.c

@@ -34,15 +34,12 @@ testCompareXMLToXMLFiles(const char *inxml, const char *outxml,
 
     virResetLastError();
 
-    if (!(dev = virNWFilterDefParseString(NULL, inXmlData)))
+    if (!(dev = virNWFilterDefParseString(NULL, inXmlData))) {
+        if (expect_error) {
+            virResetLastError();
+            goto done;
+        }
         goto fail;
-
-    if (!!virGetLastError() != expect_error)
-        goto fail;
-
-    if (expect_error) {
-        /* need to suppress the errors */
-        virResetLastError();
     }
 
     if (!(actual = virNWFilterDefFormat(dev)))
@@ -53,6 +50,7 @@ testCompareXMLToXMLFiles(const char *inxml, const char *outxml,
         goto fail;
     }
 
+ done:
     ret = 0;
 
  fail: