forked from coredns/coredns
/
request.go
397 lines (338 loc) · 8.88 KB
/
request.go
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// Package request abstracts a client's request so that all plugins will handle them in an unified way.
package request
import (
"net"
"strings"
"github.com/coredns/coredns/plugin/pkg/edns"
"github.com/miekg/dns"
"golang.org/x/net/context"
)
// Request contains some connection state and is useful in plugin.
type Request struct {
Req *dns.Msg
W dns.ResponseWriter
// Optional lowercased zone of this query.
Zone string
Context context.Context
// Cache size after first call to Size or Do.
size int
do int // 0: not, 1: true: 2: false
// TODO(miek): opt record itself as well?
// Cache lowercase qname.
name string
}
// NewWithQuestion returns a new request based on the old, but with a new question
// section in the request.
func (r *Request) NewWithQuestion(name string, typ uint16) Request {
req1 := Request{W: r.W, Req: r.Req.Copy()}
req1.Req.Question[0] = dns.Question{Name: dns.Fqdn(name), Qclass: dns.ClassINET, Qtype: typ}
return req1
}
// IP gets the (remote) IP address of the client making the request.
func (r *Request) IP() string {
ip, _, err := net.SplitHostPort(r.W.RemoteAddr().String())
if err != nil {
return r.W.RemoteAddr().String()
}
return ip
}
// Port gets the (remote) Port of the client making the request.
func (r *Request) Port() string {
_, port, err := net.SplitHostPort(r.W.RemoteAddr().String())
if err != nil {
return "0"
}
return port
}
// RemoteAddr returns the net.Addr of the client that sent the current request.
func (r *Request) RemoteAddr() string {
return r.W.RemoteAddr().String()
}
// Proto gets the protocol used as the transport. This will be udp or tcp.
func (r *Request) Proto() string { return Proto(r.W) }
// Proto gets the protocol used as the transport. This will be udp or tcp.
func Proto(w dns.ResponseWriter) string {
// FIXME(miek): why not a method on Request
if _, ok := w.RemoteAddr().(*net.UDPAddr); ok {
return "udp"
}
if _, ok := w.RemoteAddr().(*net.TCPAddr); ok {
return "tcp"
}
return "udp"
}
// Family returns the family of the transport, 1 for IPv4 and 2 for IPv6.
func (r *Request) Family() int {
var a net.IP
ip := r.W.RemoteAddr()
if i, ok := ip.(*net.UDPAddr); ok {
a = i.IP
}
if i, ok := ip.(*net.TCPAddr); ok {
a = i.IP
}
if a.To4() != nil {
return 1
}
return 2
}
// Do returns if the request has the DO (DNSSEC OK) bit set.
func (r *Request) Do() bool {
if r.do != 0 {
return r.do == doTrue
}
if o := r.Req.IsEdns0(); o != nil {
if o.Do() {
r.do = doTrue
} else {
r.do = doFalse
}
return o.Do()
}
r.do = doFalse
return false
}
// Len returns the length in bytes in the request.
func (r *Request) Len() int { return r.Req.Len() }
// Size returns if buffer size *advertised* in the requests OPT record.
// Or when the request was over TCP, we return the maximum allowed size of 64K.
func (r *Request) Size() int {
if r.size != 0 {
return r.size
}
size := 0
if o := r.Req.IsEdns0(); o != nil {
if o.Do() {
r.do = doTrue
} else {
r.do = doFalse
}
size = int(o.UDPSize())
}
// TODO(miek) move edns.Size to dnsutil?
size = edns.Size(r.Proto(), size)
r.size = size
return size
}
// SizeAndDo adds an OPT record that the reflects the intent from request.
// The returned bool indicated if an record was found and normalised.
func (r *Request) SizeAndDo(m *dns.Msg) bool {
o := r.Req.IsEdns0() // TODO(miek): speed this up
if o == nil {
return false
}
odo := o.Do()
if mo := m.IsEdns0(); mo != nil {
mo.Hdr.Name = "."
mo.Hdr.Rrtype = dns.TypeOPT
mo.SetVersion(0)
mo.SetUDPSize(o.UDPSize())
mo.Hdr.Ttl &= 0xff00 // clear flags
if odo {
mo.SetDo()
}
return true
}
o.Hdr.Name = "."
o.Hdr.Rrtype = dns.TypeOPT
o.SetVersion(0)
o.Hdr.Ttl &= 0xff00 // clear flags
if odo {
o.SetDo()
}
m.Extra = append(m.Extra, o)
return true
}
// Result is the result of Scrub.
type Result int
const (
// ScrubIgnored is returned when Scrub did nothing to the message.
ScrubIgnored Result = iota
// ScrubExtra is returned when the reply has been scrubbed by removing RRs from the additional section.
ScrubExtra
// ScrubAnswer is returned when the reply has been scrubbed by removing RRs from the answer section.
ScrubAnswer
)
// Scrub scrubs the reply message so that it will fit the client's buffer. It sets
// reply.Compress to true.
// Scrub uses binary search to find a save cut off point in the additional section.
// If even *without* the additional section the reply still doesn't fit we
// repeat this process for the answer section. If we scrub the answer section
// we set the TC bit on the reply; indicating the client should retry over TCP.
// Note, the TC bit will be set regardless of protocol, even TCP message will
// get the bit, the client should then retry with pigeons.
func (r *Request) Scrub(reply *dns.Msg) (*dns.Msg, Result) {
reply.Compress = true
size := r.Size()
rl := reply.Len()
if size >= rl {
return reply, ScrubIgnored
}
// Account for the OPT record that gets added in SizeAndDo(), subtract that length.
sub := 0
if r.Do() {
sub = optLen
}
origExtra := reply.Extra
re := len(reply.Extra) - sub
l, m := 0, 0
for l < re {
m = (l + re) / 2
reply.Extra = origExtra[:m]
rl = reply.Len()
if rl < size {
l = m + 1
continue
}
if rl > size {
re = m - 1
continue
}
if rl == size {
break
}
}
// We may come out of this loop with one rotation too many, m makes it too large, but m-1 works.
if rl > size && m > 0 {
reply.Extra = origExtra[:m-1]
rl = reply.Len()
}
if rl < size {
r.SizeAndDo(reply)
return reply, ScrubExtra
}
origAnswer := reply.Answer
ra := len(reply.Answer)
l, m = 0, 0
for l < ra {
m = (l + ra) / 2
reply.Answer = origAnswer[:m]
rl = reply.Len()
if rl < size {
l = m + 1
continue
}
if rl > size {
ra = m - 1
continue
}
if rl == size {
break
}
}
// We may come out of this loop with one rotation too many, m makes it too large, but m-1 works.
if rl > size && m > 0 {
reply.Answer = origAnswer[:m-1]
// No need to recalc length, as we don't use it. We set truncated anyway. Doing
// this extra m-1 step does make it fit in the client's buffer however.
}
// It now fits, but Truncated. We can't call sizeAndDo() because that adds a new record (OPT)
// in the additional section.
reply.Truncated = true
return reply, ScrubAnswer
}
// Type returns the type of the question as a string. If the request is malformed
// the empty string is returned.
func (r *Request) Type() string {
if r.Req == nil {
return ""
}
if len(r.Req.Question) == 0 {
return ""
}
return dns.Type(r.Req.Question[0].Qtype).String()
}
// QType returns the type of the question as an uint16. If the request is malformed
// 0 is returned.
func (r *Request) QType() uint16 {
if r.Req == nil {
return 0
}
if len(r.Req.Question) == 0 {
return 0
}
return r.Req.Question[0].Qtype
}
// Name returns the name of the question in the request. Note
// this name will always have a closing dot and will be lower cased. After a call Name
// the value will be cached. To clear this caching call Clear.
// If the request is malformed the root zone is returned.
func (r *Request) Name() string {
if r.name != "" {
return r.name
}
if r.Req == nil {
r.name = "."
return "."
}
if len(r.Req.Question) == 0 {
r.name = "."
return "."
}
r.name = strings.ToLower(dns.Name(r.Req.Question[0].Name).String())
return r.name
}
// QName returns the name of the question in the request.
// If the request is malformed the root zone is returned.
func (r *Request) QName() string {
if r.Req == nil {
return "."
}
if len(r.Req.Question) == 0 {
return "."
}
return dns.Name(r.Req.Question[0].Name).String()
}
// Class returns the class of the question in the request.
// If the request is malformed the empty string is returned.
func (r *Request) Class() string {
if r.Req == nil {
return ""
}
if len(r.Req.Question) == 0 {
return ""
}
return dns.Class(r.Req.Question[0].Qclass).String()
}
// QClass returns the class of the question in the request.
// If the request is malformed 0 returned.
func (r *Request) QClass() uint16 {
if r.Req == nil {
return 0
}
if len(r.Req.Question) == 0 {
return 0
}
return r.Req.Question[0].Qclass
}
// ErrorMessage returns an error message suitable for sending
// back to the client.
func (r *Request) ErrorMessage(rcode int) *dns.Msg {
m := new(dns.Msg)
m.SetRcode(r.Req, rcode)
return m
}
// Clear clears all caching from Request s.
func (r *Request) Clear() {
r.name = ""
}
// Match checks if the reply matches the qname and qtype from the request, it returns
// false when they don't match.
func (r *Request) Match(reply *dns.Msg) bool {
if len(reply.Question) != 1 {
return false
}
if strings.ToLower(reply.Question[0].Name) != r.Name() {
return false
}
if reply.Question[0].Qtype != r.QType() {
return false
}
return true
}
const (
// TODO(miek): make this less awkward.
doTrue = 1
doFalse = 2
optLen = 12 // OPT record length.
)