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Implement a DNS zone
Full implementation, DNS (and in the future DNSSEC). Returns answer in a hopefully standards compliant way. Testing with my miek.nl zone are included as well. This should correctly handle nodata, nxdomain and cnames.
This commit is contained in:
Miek Gieben
585
middleware/file/tree/tree.go
Normal file
585
middleware/file/tree/tree.go
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@@ -0,0 +1,585 @@
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// Copyright ©2012 The bíogo Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found at the end of this file.
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// Package tree implements Left-Leaning Red Black trees as described by Robert Sedgewick.
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//
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// More details relating to the implementation are available at the following locations:
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//
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// http://www.cs.princeton.edu/~rs/talks/LLRB/LLRB.pdf
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// http://www.cs.princeton.edu/~rs/talks/LLRB/Java/RedBlackBST.java
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// http://www.teachsolaisgames.com/articles/balanced_left_leaning.html
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//
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// Heavily modified by Miek Gieben for use in DNS zones.
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package tree
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// TODO(miek): locking? lockfree
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// TODO(miek): fix docs
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import (
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"strings"
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"github.com/miekg/dns"
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)
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const (
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TD234 = iota
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BU23
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)
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// Operation mode of the LLRB tree.
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const Mode = BU23
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func init() {
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if Mode != TD234 && Mode != BU23 {
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panic("tree: unknown mode")
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}
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}
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type Elem struct {
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m map[uint16][]dns.RR
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}
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// newElem returns a new elem
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func newElem(rr dns.RR) *Elem {
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e := Elem{m: make(map[uint16][]dns.RR)}
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e.m[rr.Header().Rrtype] = []dns.RR{rr}
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return &e
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}
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// Types returns the types from with type qtype from e.
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func (e *Elem) Types(qtype uint16) []dns.RR {
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if rrs, ok := e.m[qtype]; ok {
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// TODO(miek): length should never be zero here.
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return rrs
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}
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return nil
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}
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func (e *Elem) All() []dns.RR {
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list := []dns.RR{}
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for _, rrs := range e.m {
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list = append(list, rrs...)
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}
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return list
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}
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func (e *Elem) Insert(rr dns.RR) {
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t := rr.Header().Rrtype
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if e.m == nil {
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e.m = make(map[uint16][]dns.RR)
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e.m[t] = []dns.RR{rr}
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return
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}
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rrs, ok := e.m[t]
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if !ok {
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e.m[t] = []dns.RR{rr}
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return
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}
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for _, er := range rrs {
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if equalRdata(er, rr) {
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return
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}
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}
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rrs = append(rrs, rr)
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e.m[t] = rrs
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}
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// Delete removes rr from e. When e is empty after the removal the returned bool is true.
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func (e *Elem) Delete(rr dns.RR) (empty bool) {
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t := rr.Header().Rrtype
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if e.m == nil {
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return
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}
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rrs, ok := e.m[t]
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if !ok {
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return
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}
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for i, er := range rrs {
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if equalRdata(er, rr) {
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rrs = removeFromSlice(rrs, i)
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e.m[t] = rrs
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empty = len(rrs) == 0
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if empty {
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delete(e.m, t)
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}
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return
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}
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}
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return
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}
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// TODO(miek): need case ignore compare that is more efficient.
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func Less(a *Elem, rr dns.RR) int {
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aname := ""
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for _, ar := range a.m {
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aname = strings.ToLower(ar[0].Header().Name)
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break
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}
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rname := strings.ToLower(rr.Header().Name)
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if aname == rname {
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return 0
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}
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if aname < rname {
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return -1
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}
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return 1
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}
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// Assuming the same type and name this will check if the rdata is equal as well.
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func equalRdata(a, b dns.RR) bool {
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switch x := a.(type) {
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case *dns.A:
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return x.A.Equal(b.(*dns.A).A)
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case *dns.AAAA:
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return x.AAAA.Equal(b.(*dns.AAAA).AAAA)
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case *dns.MX:
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if x.Mx == b.(*dns.MX).Mx && x.Preference == b.(*dns.MX).Preference {
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return true
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}
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}
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return false
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}
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// removeFromSlice removes index i from the slice.
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func removeFromSlice(rrs []dns.RR, i int) []dns.RR {
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if i >= len(rrs) {
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return rrs
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}
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rrs = append(rrs[:i], rrs[i+1:]...)
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return rrs
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}
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// A Color represents the color of a Node.
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type Color bool
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const (
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// Red as false give us the defined behaviour that new nodes are red. Although this
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// is incorrect for the root node, that is resolved on the first insertion.
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Red Color = false
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Black Color = true
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)
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// A Node represents a node in the LLRB tree.
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type Node struct {
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Elem *Elem
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Left, Right *Node
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Color Color
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}
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// A Tree manages the root node of an LLRB tree. Public methods are exposed through this type.
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type Tree struct {
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Root *Node // Root node of the tree.
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Count int // Number of elements stored.
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}
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// Helper methods
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// color returns the effect color of a Node. A nil node returns black.
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func (n *Node) color() Color {
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if n == nil {
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return Black
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}
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return n.Color
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}
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// (a,c)b -rotL-> ((a,)b,)c
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func (n *Node) rotateLeft() (root *Node) {
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// Assumes: n has two children.
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root = n.Right
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n.Right = root.Left
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root.Left = n
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root.Color = n.Color
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n.Color = Red
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return
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}
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// (a,c)b -rotR-> (,(,c)b)a
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func (n *Node) rotateRight() (root *Node) {
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// Assumes: n has two children.
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root = n.Left
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n.Left = root.Right
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root.Right = n
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root.Color = n.Color
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n.Color = Red
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return
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}
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// (aR,cR)bB -flipC-> (aB,cB)bR | (aB,cB)bR -flipC-> (aR,cR)bB
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func (n *Node) flipColors() {
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// Assumes: n has two children.
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n.Color = !n.Color
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n.Left.Color = !n.Left.Color
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n.Right.Color = !n.Right.Color
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}
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// fixUp ensures that black link balance is correct, that red nodes lean left,
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// and that 4 nodes are split in the case of BU23 and properly balanced in TD234.
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func (n *Node) fixUp() *Node {
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if n.Right.color() == Red {
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if Mode == TD234 && n.Right.Left.color() == Red {
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n.Right = n.Right.rotateRight()
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}
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n = n.rotateLeft()
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}
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if n.Left.color() == Red && n.Left.Left.color() == Red {
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n = n.rotateRight()
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}
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if Mode == BU23 && n.Left.color() == Red && n.Right.color() == Red {
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n.flipColors()
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}
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return n
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}
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func (n *Node) moveRedLeft() *Node {
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n.flipColors()
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if n.Right.Left.color() == Red {
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n.Right = n.Right.rotateRight()
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n = n.rotateLeft()
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n.flipColors()
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if Mode == TD234 && n.Right.Right.color() == Red {
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n.Right = n.Right.rotateLeft()
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}
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}
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return n
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}
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func (n *Node) moveRedRight() *Node {
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n.flipColors()
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if n.Left.Left.color() == Red {
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n = n.rotateRight()
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n.flipColors()
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}
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return n
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}
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// Len returns the number of elements stored in the Tree.
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func (t *Tree) Len() int {
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return t.Count
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}
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// Get returns the first match of q in the Tree. If insertion without
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// replacement is used, this is probably not what you want.
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func (t *Tree) Get(rr dns.RR) *Elem {
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if t.Root == nil {
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return nil
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}
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n := t.Root.search(rr)
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if n == nil {
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return nil
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}
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return n.Elem
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}
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func (n *Node) search(rr dns.RR) *Node {
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for n != nil {
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switch c := Less(n.Elem, rr); {
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case c == 0:
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return n
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case c < 0:
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n = n.Left
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default:
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n = n.Right
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}
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}
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return n
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}
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// Insert inserts the Comparable e into the Tree at the first match found
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// with e or when a nil node is reached. Insertion without replacement can
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// specified by ensuring that e.Compare() never returns 0. If insert without
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// replacement is performed, a distinct query Comparable must be used that
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// can return 0 with a Compare() call.
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func (t *Tree) Insert(rr dns.RR) {
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var d int
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t.Root, d = t.Root.insert(rr)
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t.Count += d
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t.Root.Color = Black
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}
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func (n *Node) insert(rr dns.RR) (root *Node, d int) {
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if n == nil {
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return &Node{Elem: newElem(rr)}, 1
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} else if n.Elem == nil {
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n.Elem = newElem(rr)
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return n, 1
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}
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if Mode == TD234 {
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if n.Left.color() == Red && n.Right.color() == Red {
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n.flipColors()
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}
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}
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switch c := Less(n.Elem, rr); {
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case c == 0:
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n.Elem.Insert(rr)
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case c < 0:
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n.Left, d = n.Left.insert(rr)
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default:
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n.Right, d = n.Right.insert(rr)
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}
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if n.Right.color() == Red && n.Left.color() == Black {
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n = n.rotateLeft()
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}
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if n.Left.color() == Red && n.Left.Left.color() == Red {
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n = n.rotateRight()
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}
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if Mode == BU23 {
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if n.Left.color() == Red && n.Right.color() == Red {
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n.flipColors()
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}
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}
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root = n
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return
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}
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// DeleteMin deletes the node with the minimum value in the tree. If insertion without
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// replacement has been used, the left-most minimum will be deleted.
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func (t *Tree) DeleteMin() {
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if t.Root == nil {
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return
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}
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var d int
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t.Root, d = t.Root.deleteMin()
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t.Count += d
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if t.Root == nil {
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return
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}
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t.Root.Color = Black
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}
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func (n *Node) deleteMin() (root *Node, d int) {
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if n.Left == nil {
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return nil, -1
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}
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if n.Left.color() == Black && n.Left.Left.color() == Black {
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n = n.moveRedLeft()
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}
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n.Left, d = n.Left.deleteMin()
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root = n.fixUp()
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return
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}
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// DeleteMax deletes the node with the maximum value in the tree. If insertion without
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// replacement has been used, the right-most maximum will be deleted.
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func (t *Tree) DeleteMax() {
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if t.Root == nil {
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return
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}
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var d int
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t.Root, d = t.Root.deleteMax()
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t.Count += d
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if t.Root == nil {
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return
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}
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t.Root.Color = Black
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}
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func (n *Node) deleteMax() (root *Node, d int) {
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if n.Left != nil && n.Left.color() == Red {
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n = n.rotateRight()
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}
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if n.Right == nil {
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return nil, -1
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}
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if n.Right.color() == Black && n.Right.Left.color() == Black {
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n = n.moveRedRight()
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}
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n.Right, d = n.Right.deleteMax()
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root = n.fixUp()
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return
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}
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// Delete removes rr from the tree, is the node turns empty, that node is return with DeleteNode.
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func (t *Tree) Delete(rr dns.RR) {
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if t.Root == nil {
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return
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}
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// If there is an element, remove the rr from it
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el := t.Get(rr)
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if el == nil {
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t.DeleteNode(rr)
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return
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}
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// delete from this element
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empty := el.Delete(rr)
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if empty {
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t.DeleteNode(rr)
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return
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}
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}
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// DeleteNode deletes the node that matches e according to Compare(). Note that Compare must
|
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// identify the target node uniquely and in cases where non-unique keys are used,
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// attributes used to break ties must be used to determine tree ordering during insertion.
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func (t *Tree) DeleteNode(rr dns.RR) {
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if t.Root == nil {
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return
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}
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var d int
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t.Root, d = t.Root.delete(rr)
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t.Count += d
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if t.Root == nil {
|
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return
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}
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t.Root.Color = Black
|
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}
|
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func (n *Node) delete(rr dns.RR) (root *Node, d int) {
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if Less(n.Elem, rr) < 0 {
|
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if n.Left != nil {
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if n.Left.color() == Black && n.Left.Left.color() == Black {
|
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n = n.moveRedLeft()
|
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}
|
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n.Left, d = n.Left.delete(rr)
|
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}
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} else {
|
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if n.Left.color() == Red {
|
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n = n.rotateRight()
|
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}
|
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if n.Right == nil && Less(n.Elem, rr) == 0 {
|
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return nil, -1
|
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}
|
||||
if n.Right != nil {
|
||||
if n.Right.color() == Black && n.Right.Left.color() == Black {
|
||||
n = n.moveRedRight()
|
||||
}
|
||||
if Less(n.Elem, rr) == 0 {
|
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n.Elem = n.Right.min().Elem
|
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n.Right, d = n.Right.deleteMin()
|
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} else {
|
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n.Right, d = n.Right.delete(rr)
|
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}
|
||||
}
|
||||
}
|
||||
|
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root = n.fixUp()
|
||||
|
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return
|
||||
}
|
||||
|
||||
// Return the minimum value stored in the tree. This will be the left-most minimum value if
|
||||
// insertion without replacement has been used.
|
||||
func (t *Tree) Min() *Elem {
|
||||
if t.Root == nil {
|
||||
return nil
|
||||
}
|
||||
return t.Root.min().Elem
|
||||
}
|
||||
|
||||
func (n *Node) min() *Node {
|
||||
for ; n.Left != nil; n = n.Left {
|
||||
}
|
||||
return n
|
||||
}
|
||||
|
||||
// Return the maximum value stored in the tree. This will be the right-most maximum value if
|
||||
// insertion without replacement has been used.
|
||||
func (t *Tree) Max() *Elem {
|
||||
if t.Root == nil {
|
||||
return nil
|
||||
}
|
||||
return t.Root.max().Elem
|
||||
}
|
||||
|
||||
func (n *Node) max() *Node {
|
||||
for ; n.Right != nil; n = n.Right {
|
||||
}
|
||||
return n
|
||||
}
|
||||
|
||||
// Floor returns the greatest value equal to or less than the query q according to q.Compare().
|
||||
func (t *Tree) Floor(rr dns.RR) *Elem {
|
||||
if t.Root == nil {
|
||||
return nil
|
||||
}
|
||||
n := t.Root.floor(rr)
|
||||
if n == nil {
|
||||
return nil
|
||||
}
|
||||
return n.Elem
|
||||
}
|
||||
|
||||
func (n *Node) floor(rr dns.RR) *Node {
|
||||
if n == nil {
|
||||
return nil
|
||||
}
|
||||
switch c := Less(n.Elem, rr); {
|
||||
case c == 0:
|
||||
return n
|
||||
case c < 0:
|
||||
return n.Left.floor(rr)
|
||||
default:
|
||||
if r := n.Right.floor(rr); r != nil {
|
||||
return r
|
||||
}
|
||||
}
|
||||
return n
|
||||
}
|
||||
|
||||
// Ceil returns the smallest value equal to or greater than the query q according to q.Compare().
|
||||
func (t *Tree) Ceil(rr dns.RR) *Elem {
|
||||
if t.Root == nil {
|
||||
return nil
|
||||
}
|
||||
n := t.Root.ceil(rr)
|
||||
if n == nil {
|
||||
return nil
|
||||
}
|
||||
return n.Elem
|
||||
}
|
||||
|
||||
func (n *Node) ceil(rr dns.RR) *Node {
|
||||
if n == nil {
|
||||
return nil
|
||||
}
|
||||
switch c := Less(n.Elem, rr); {
|
||||
case c == 0:
|
||||
return n
|
||||
case c > 0:
|
||||
return n.Right.ceil(rr)
|
||||
default:
|
||||
if l := n.Left.ceil(rr); l != nil {
|
||||
return l
|
||||
}
|
||||
}
|
||||
return n
|
||||
}
|
||||
|
||||
/*
|
||||
Copyright ©2012 The bíogo Authors. All rights reserved.
|
||||
|
||||
Redistribution and use in source and binary forms, with or without
|
||||
modification, are permitted provided that the following conditions are met:
|
||||
|
||||
* Redistributions of source code must retain the above copyright
|
||||
notice, this list of conditions and the following disclaimer.
|
||||
* Redistributions in binary form must reproduce the above copyright
|
||||
notice, this list of conditions and the following disclaimer in the
|
||||
documentation and/or other materials provided with the distribution.
|
||||
* Neither the name of the bíogo project nor the names of its authors and
|
||||
contributors may be used to endorse or promote products derived from this
|
||||
software without specific prior written permission.
|
||||
|
||||
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
|
||||
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
||||
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
|
||||
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||||
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
||||
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
||||
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
||||
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||||
*/
|
||||
Reference in New Issue
Block a user