135 lines
2.7 KiB
Go
135 lines
2.7 KiB
Go
// Copyright 2009 The Go 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 in the LICENSE file.
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// Extended and bugfixes by Miek Gieben
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// Package dns implements a full featured interface to the DNS.
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// The package allows full control over what is send out to the DNS.
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//
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// Resource Records are native types. They are not stored in wire format.
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// Basic usage pattern for creating new Resource Record:
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//
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// r := new(RR_TXT)
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// r.Hdr = RR_Header{Name: "a.miek.nl", Rrtype: TypeTXT, Class: ClassINET, Ttl: 3600}
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// r.TXT = "This is the content of the TXT record"
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//
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package dns
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import (
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"strconv"
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)
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// For RFC1982 (Serial Arithmetic) calculations in 32 bits.
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const Year68 = 2 << (32 - 1)
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// Error represents a DNS error
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type Error struct {
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Error string
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Name string
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Server string
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Timeout bool
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}
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func (e *Error) String() string {
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if e == nil {
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return "<nil>"
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}
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return e.Error
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}
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type RR interface {
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Header() *RR_Header
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String() string
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}
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// An RRset is a slice of RRs.
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type RRset []RR
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func (r RRset) Len() int { return len(r) }
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func (r RRset) Less(i, j int) bool { return r[i].Header().Name < r[j].Header().Name }
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func (r RRset) Swap(i, j int) { r[i], r[j] = r[j], r[i] }
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// Check if the RRset is RFC 2181 compliant
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func (r RRset) Ok() bool {
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ttl := r[0].Header().Ttl
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name := r[0].Header().Name
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class := r[0].Header().Class
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for _, rr := range r[1:] {
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if rr.Header().Ttl != ttl {
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return false
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}
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if rr.Header().Name != name {
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return false
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}
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if rr.Header().Class != class {
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return false
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}
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}
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return true
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}
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// DNS resource records.
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// There are many types of messages,
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// but they all share the same header.
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type RR_Header struct {
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Name string "domain-name"
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Rrtype uint16
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Class uint16
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Ttl uint32
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Rdlength uint16 // length of data after header
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}
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func (h *RR_Header) Header() *RR_Header {
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return h
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}
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func (h *RR_Header) String() string {
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var s string
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if h.Rrtype == TypeOPT {
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s = ";"
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// and maybe other things
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}
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if len(h.Name) == 0 {
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s += ".\t"
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} else {
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s += h.Name + "\t"
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}
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s = s + strconv.Itoa(int(h.Ttl)) + "\t"
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if _, ok := Class_str[h.Class]; ok {
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s += Class_str[h.Class] + "\t"
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} else {
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s += "CLASS" + strconv.Itoa(int(h.Class)) + "\t"
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}
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if _, ok := Rr_str[h.Rrtype]; ok {
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s += Rr_str[h.Rrtype] + "\t"
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} else {
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s += "TYPE" + strconv.Itoa(int(h.Rrtype)) + "\t"
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}
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return s
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}
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// Return the number of labels in a domain name.
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func LabelCount(a string) (c uint8) {
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// walk the string and count the dots
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// except when it is escaped
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esc := false
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for _, v := range a {
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switch v {
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case '.':
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if esc {
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esc = !esc
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continue
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}
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c++
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case '\\':
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esc = true
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}
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}
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return
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}
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