Address side effects of accessing vars via index

Address side effect of accessing a variable via an index: Filters
accessing a variable where an element is accessed that is beyond the
size of the list (for example $TEST[10] and only 2 elements are available)
cannot instantiate that filter. Test for this and report proper error
to user.

src/conf/nwfilter_params.c

@@ -1072,3 +1072,32 @@ virNWFilterVarAccessGetIntIterId(const virNWFilterVarAccessPtr vap)
 {
     return vap->u.index.intIterId;
 }
+
+bool
+virNWFilterVarAccessIsAvailable(const virNWFilterVarAccessPtr varAccess,
+                                const virNWFilterHashTablePtr hash)
+{
+    const char *varName = virNWFilterVarAccessGetVarName(varAccess);
+    const char *res;
+    unsigned int idx;
+    virNWFilterVarValuePtr varValue;
+
+    varValue = virHashLookup(hash->hashTable, varName);
+    if (!varValue)
+        return false;
+
+    switch (virNWFilterVarAccessGetType(varAccess)) {
+    case VIR_NWFILTER_VAR_ACCESS_ELEMENT:
+        idx = virNWFilterVarAccessGetIndex(varAccess);
+        res = virNWFilterVarValueGetNthValue(varValue, idx);
+        if (res == NULL)
+            return false;
+        break;
+    case VIR_NWFILTER_VAR_ACCESS_ITERATOR:
+        break;
+    case VIR_NWFILTER_VAR_ACCESS_LAST:
+        return false;
+    }
+
+    return true;
+}

src/conf/nwfilter_params.h

@@ -125,7 +125,8 @@ enum virNWFilterVarAccessType virNWFilterVarAccessGetType(
                                            const virNWFilterVarAccessPtr vap);
 unsigned int virNWFilterVarAccessGetIterId(const virNWFilterVarAccessPtr vap);
 unsigned int virNWFilterVarAccessGetIndex(const virNWFilterVarAccessPtr vap);
-
+bool virNWFilterVarAccessIsAvailable(const virNWFilterVarAccessPtr vap,
+                                     const virNWFilterHashTablePtr hash);
 
 typedef struct _virNWFilterVarCombIterEntry virNWFilterVarCombIterEntry;
 typedef virNWFilterVarCombIterEntry *virNWFilterVarCombIterEntryPtr;

src/libvirt_private.syms

@@ -833,6 +833,8 @@ virNWFilterHashTablePut;
 virNWFilterHashTablePutAll;
 virNWFilterHashTableRemoveEntry;
 virNWFilterVarAccessGetVarName;
+virNWFilterVarAccessIsAvailable;
+virNWFilterVarAccessPrint;
 virNWFilterVarCombIterCreate;
 virNWFilterVarCombIterFree;
 virNWFilterVarCombIterGetVarValue;

src/nwfilter/nwfilter_gentech_driver.c

@@ -501,16 +501,29 @@ virNWFilterDetermineMissingVarsRec(virNWFilterDefPtr filter,
         if (rule) {
             /* check all variables of this rule */
             for (j = 0; j < rule->nVarAccess; j++) {
-                const char *varName;
+                if (!virNWFilterVarAccessIsAvailable(rule->varAccess[j],
-                varName = virNWFilterVarAccessGetVarName(rule->varAccess[j]);
+                                                     vars)) {
-                if (!virHashLookup(vars->hashTable, varName)) {
+                    const char *varAccess;
-                    val = virNWFilterVarValueCreateSimpleCopyValue("1");
+                    virBuffer buf = VIR_BUFFER_INITIALIZER;
-                    if (!val) {
+
+                    virNWFilterVarAccessPrint(rule->varAccess[j], &buf);
+                    if (virBufferError(&buf)) {
+                        virReportOOMError();
                         rc = -1;
                         break;
                     }
-                    virNWFilterHashTablePut(missing_vars, varName,
+
+                    val = virNWFilterVarValueCreateSimpleCopyValue("1");
+                    if (!val) {
+                        virBufferFreeAndReset(&buf);
+                        rc = -1;
+                        break;
+                    }
+
+                    varAccess = virBufferContentAndReset(&buf);
+                    virNWFilterHashTablePut(missing_vars, varAccess,
                                             val, 1);
+                    VIR_FREE(varAccess);
                 }
             }
             if (rc)
@@ -752,7 +765,7 @@ err_unresolvable_vars:
     if (buf) {
         virNWFilterReportError(VIR_ERR_INTERNAL_ERROR,
                    _("Cannot instantiate filter due to unresolvable "
-                     "variables: %s"), buf);
+                     "variables or unavailable list elements: %s"), buf);
         VIR_FREE(buf);
     }