private static Node GetPreviousSubDomainZoneNode(byte[] key, Node currentNode, int baseDepth)
{
int k;
NodeValue currentValue = currentNode.Value;
if (currentValue is null)
{
//key value does not exists
if (currentNode.Children is null)
{
//no children available; move to previous sibling
k = currentNode.K - 1; //find previous node from sibling starting at k - 1
currentNode = currentNode.Parent;
}
else
{
if (key.Length == currentNode.Depth)
{
//current node belongs to the key
k = currentNode.K - 1; //find previous node from sibling starting at k - 1
currentNode = currentNode.Parent;
}
else
{
//find the previous node for the given k in current node's children
k = key[currentNode.Depth];
}
}
}
else
{
int x = DnsNSECRecordData.CanonicalComparison(currentValue.Key, key);
if (x == 0)
{
//current node value matches the key
k = currentNode.K - 1; //find previous node from sibling starting at k - 1
currentNode = currentNode.Parent;
}
else if (x > 0)
{
//current node value is larger for the key
k = currentNode.K - 1; //find previous node from sibling starting at k - 1
currentNode = currentNode.Parent;
}
else
{
//current node value is smaller for the key
if (currentNode.Children is null)
{
//the current node is previous node since no children exists and value is smaller for the key
return(currentNode);
}
else
{
//find the previous node for the given k in current node's children
k = key[currentNode.Depth];
}
}
}
//start reverse tree traversal
while ((currentNode is not null) && (currentNode.Depth >= baseDepth))
{
Node[] children = currentNode.Children;
if (children is not null)
{
//find previous child node
Node child = null;
for (int i = k; i > -1; i--)
{
child = Volatile.Read(ref children[i]);
if (child is not null)
{
bool childNodeHasApexZone = false;
NodeValue childValue = child.Value;
if (childValue is not null)
{
AuthZoneNode authZoneNode = childValue.Value;
if (authZoneNode is not null)
{
if (authZoneNode.ApexZone is not null)
{
childNodeHasApexZone = true; //must stop checking children of the apex of the sub zone
}
}
}
if (!childNodeHasApexZone && child.Children is not null)
{
break; //child has further children so check them first
}
if (childValue is not null)
{
AuthZoneNode authZoneNode = childValue.Value;
if (authZoneNode is not null)
{
if (authZoneNode.ParentSideZone is not null)
{
//is sub domain zone
return(child); //child has value so return it
}
if (authZoneNode.ApexZone is not null)
{
//is apex zone
//skip to next child to avoid listing this auth zone's sub domains
child = null; //set null to avoid child being set as current after the loop
}
}
}
}
}
if (child is not null)
{
//make found child as current
k = children.Length - 1;
currentNode = child;
continue; //start over
}
}
//no child node available; check for current node value
{
NodeValue value = currentNode.Value;
if (value is not null)
{
AuthZoneNode authZoneNode = value.Value;
if (authZoneNode is not null)
{
if ((authZoneNode.ApexZone is not null) && (currentNode.Depth == baseDepth))
{
//current node contains apex zone for the base depth i.e. current zone; return it
return(currentNode);
}
if (authZoneNode.ParentSideZone is not null)
{
//current node contains sub domain zone; return it
return(currentNode);
}
}
}
}
//move up to parent node for previous sibling
k = currentNode.K - 1;
currentNode = currentNode.Parent;
}
return(null);
}
private static Node GetNextSubDomainZoneNode(byte[] key, Node currentNode, int baseDepth)
{
int k;
NodeValue currentValue = currentNode.Value;
if (currentValue is null)
{
//key value does not exists
if (currentNode.Children is null)
{
//no children available; move to next sibling
k = currentNode.K + 1; //find next node from sibling starting at k + 1
currentNode = currentNode.Parent;
}
else
{
if (key.Length == currentNode.Depth)
{
//current node belongs to the key
k = 0; //find next node from first child of current node
}
else
{
//find next node for the given k in current node's children
k = key[currentNode.Depth];
}
}
}
else
{
//check if node contains apex zone
bool foundApexZone = false;
if (currentNode.Depth > baseDepth)
{
AuthZoneNode authZoneNode = currentValue.Value;
if (authZoneNode is not null)
{
ApexZone apexZone = authZoneNode.ApexZone;
if (apexZone is not null)
{
foundApexZone = true;
}
}
}
if (foundApexZone)
{
//current contains apex for a sub zone; move up to parent node
k = currentNode.K + 1; //find next node from sibling starting at k + 1
currentNode = currentNode.Parent;
}
else
{
int x = DnsNSECRecordData.CanonicalComparison(currentValue.Key, key);
if (x == 0)
{
//current node value matches the key
k = 0; //find next node from children starting at k
}
else if (x > 0)
{
//current node value is larger for the key thus current is the next node
return(currentNode);
}
else
{
//current node value is smaller for the key
k = key[currentNode.Depth]; //find next node from children starting at k = key[depth]
}
}
}
//start tree traversal
while ((currentNode is not null) && (currentNode.Depth >= baseDepth))
{
Node[] children = currentNode.Children;
if (children is not null)
{
//find next child node
Node child = null;
for (int i = k; i < children.Length; i++)
{
child = Volatile.Read(ref children[i]);
if (child is not null)
{
NodeValue childValue = child.Value;
if (childValue is not null)
{
AuthZoneNode authZoneNode = childValue.Value;
if (authZoneNode is not null)
{
if (authZoneNode.ParentSideZone is not null)
{
//is sub domain zone
return(child); //child has value so return it
}
if (authZoneNode.ApexZone is not null)
{
//is apex zone
//skip to next child to avoid listing this auth zone's sub domains
child = null; //set null to avoid child being set as current after the loop
continue;
}
}
}
if (child.Children is not null)
{
break;
}
}
}
if (child is not null)
{
//make found child as current
k = 0;
currentNode = child;
continue; //start over
}
}
//no child nodes available; move up to parent node
k = currentNode.K + 1;
currentNode = currentNode.Parent;
}
return(null);
}
