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Doh: put in pkg/doh (#1946)

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* DoH: put in pkg/doh

Factor out the DoH stuff into its own package, add function to request
a DoH response. This can be used by forward (and maybe proxy) to
implement DoH client support.

Signed-off-by: Miek Gieben <miek@miek.nl>

* lint

Signed-off-by: Miek Gieben <miek@miek.nl>

* ... and make it compile

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben 2018-07-07 08:22:07 +01:00 • committed by GitHub
parent bc50901234
commit 30a788fd3a
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
5 changed files with 175 additions and 134 deletions
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51
core/dnsserver/https.go
View file

@ -1,62 +1,11 @@
package dnsserver
import (
"encoding/base64"
"fmt"
"io/ioutil"
"net"
"net/http"
"github.com/coredns/coredns/plugin/pkg/nonwriter"
"github.com/miekg/dns"
)
// mimeTypeDOH is the DoH mimetype that should be used.
const mimeTypeDOH = "application/dns-message"
// pathDOH is the URL path that should be used.
const pathDOH = "/dns-query"
// postRequestToMsg extracts the dns message from the request body.
func postRequestToMsg(req *http.Request) (*dns.Msg, error) {
defer req.Body.Close()
buf, err := ioutil.ReadAll(req.Body)
if err != nil {
return nil, err
}
m := new(dns.Msg)
err = m.Unpack(buf)
return m, err
}
// getRequestToMsg extract the dns message from the GET request.
func getRequestToMsg(req *http.Request) (*dns.Msg, error) {
values := req.URL.Query()
b64, ok := values["dns"]
if !ok {
return nil, fmt.Errorf("no 'dns' query parameter found")
}
if len(b64) != 1 {
return nil, fmt.Errorf("multiple 'dns' query values found")
}
return base64ToMsg(b64[0])
}
func base64ToMsg(b64 string) (*dns.Msg, error) {
buf, err := b64Enc.DecodeString(b64)
if err != nil {
return nil, err
}
m := new(dns.Msg)
err = m.Unpack(buf)
return m, err
}
var b64Enc = base64.RawURLEncoding
// DoHWriter is a nonwriter.Writer that adds more specific LocalAddr and RemoteAddr methods.
type DoHWriter struct {
nonwriter.Writer

66
core/dnsserver/https_test.go
View file

@ -1,66 +0,0 @@
package dnsserver
import (
"bytes"
"encoding/base64"
"net/http"
"testing"
"github.com/miekg/dns"
)
func TestPostRequest(t *testing.T) {
const ex = "example.org."
m := new(dns.Msg)
m.SetQuestion(ex, dns.TypeDNSKEY)
out, _ := m.Pack()
req, err := http.NewRequest(http.MethodPost, "https://"+ex+pathDOH+"?bla=foo:443", bytes.NewReader(out))
if err != nil {
t.Errorf("Failure to make request: %s", err)
}
req.Header.Set("content-type", mimeTypeDOH)
req.Header.Set("accept", mimeTypeDOH)
m, err = postRequestToMsg(req)
if err != nil {
t.Fatalf("Failure to get message from request: %s", err)
}
if x := m.Question[0].Name; x != ex {
t.Errorf("Qname expected %s, got %s", ex, x)
}
if x := m.Question[0].Qtype; x != dns.TypeDNSKEY {
t.Errorf("Qname expected %d, got %d", x, dns.TypeDNSKEY)
}
}
func TestGetRequest(t *testing.T) {
const ex = "example.org."
m := new(dns.Msg)
m.SetQuestion(ex, dns.TypeDNSKEY)
out, _ := m.Pack()
b64 := base64.RawURLEncoding.EncodeToString(out)
req, err := http.NewRequest(http.MethodGet, "https://"+ex+pathDOH+"?dns="+b64, nil)
if err != nil {
t.Errorf("Failure to make request: %s", err)
}
req.Header.Set("content-type", mimeTypeDOH)
req.Header.Set("accept", mimeTypeDOH)
m, err = getRequestToMsg(req)
if err != nil {
t.Fatalf("Failure to get message from request: %s", err)
}
if x := m.Question[0].Name; x != ex {
t.Errorf("Qname expected %s, got %s", ex, x)
}
if x := m.Question[0].Qtype; x != dns.TypeDNSKEY {
t.Errorf("Qname expected %d, got %d", x, dns.TypeDNSKEY)
}
}

21
core/dnsserver/server_https.go
View file

@ -10,9 +10,8 @@ import (
"time"
"github.com/coredns/coredns/plugin/pkg/dnsutil"
"github.com/coredns/coredns/plugin/pkg/doh"
"github.com/coredns/coredns/plugin/pkg/response"
"github.com/miekg/dns"
)
// ServerHTTPS represents an instance of a DNS-over-HTTPS server.
@ -99,24 +98,12 @@ func (s *ServerHTTPS) Stop() error {
// chain, converts it back and write it to the client.
func (s *ServerHTTPS) ServeHTTP(w http.ResponseWriter, r *http.Request) {
msg := new(dns.Msg)
var err error
if r.URL.Path != pathDOH {
if r.URL.Path != doh.Path {
http.Error(w, "", http.StatusNotFound)
return
}
switch r.Method {
case http.MethodPost:
msg, err = postRequestToMsg(r)
case http.MethodGet:
msg, err = getRequestToMsg(r)
default:
http.Error(w, "", http.StatusMethodNotAllowed)
return
}
msg, err := doh.RequestToMsg(r)
if err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
@ -136,7 +123,7 @@ func (s *ServerHTTPS) ServeHTTP(w http.ResponseWriter, r *http.Request) {
mt, _ := response.Typify(dw.Msg, time.Now().UTC())
age := dnsutil.MinimalTTL(dw.Msg, mt)
w.Header().Set("Content-Type", mimeTypeDOH)
w.Header().Set("Content-Type", doh.MimeType)
w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%f", age.Seconds()))
w.Header().Set("Content-Length", strconv.Itoa(len(buf)))
w.WriteHeader(http.StatusOK)

119
plugin/pkg/doh/doh.go Normal file
View file

@ -0,0 +1,119 @@
package doh
import (
"bytes"
"encoding/base64"
"fmt"
"io"
"io/ioutil"
"net/http"
"github.com/miekg/dns"
)
// MimeType is the DoH mimetype that should be used.
const MimeType = "application/dns-message"
// Path is the URL path that should be used.
const Path = "/dns-query"
// NewRequest returns a new DoH request given a method, URL (without any paths, so exclude /dns-query) and dns.Msg.
func NewRequest(method, url string, m *dns.Msg) (*http.Request, error) {
buf, err := m.Pack()
if err != nil {
return nil, err
}
switch method {
case http.MethodGet:
b64 := base64.RawURLEncoding.EncodeToString(buf)
req, err := http.NewRequest(http.MethodGet, "https://"+url+Path+"?dns="+b64, nil)
if err != nil {
return req, err
}
req.Header.Set("content-type", MimeType)
req.Header.Set("accept", MimeType)
return req, nil
case http.MethodPost:
req, err := http.NewRequest(http.MethodPost, "https://"+url+Path+"?bla=foo:443", bytes.NewReader(buf))
if err != nil {
return req, err
}
req.Header.Set("content-type", MimeType)
req.Header.Set("accept", MimeType)
return req, nil
default:
return nil, fmt.Errorf("method not allowed: %s", method)
}
}
// ResponseToMsg converts a http.Repsonse to a dns message.
func ResponseToMsg(resp *http.Response) (*dns.Msg, error) {
defer resp.Body.Close()
return toMsg(resp.Body)
}
// RequestToMsg converts a http.Request to a dns message.
func RequestToMsg(req *http.Request) (*dns.Msg, error) {
switch req.Method {
case http.MethodGet:
return requestToMsgGet(req)
case http.MethodPost:
return requestToMsgPost(req)
default:
return nil, fmt.Errorf("method not allowed: %s", req.Method)
}
}
// requestToMsgPost extracts the dns message from the request body.
func requestToMsgPost(req *http.Request) (*dns.Msg, error) {
defer req.Body.Close()
return toMsg(req.Body)
}
// requestToMsgGet extract the dns message from the GET request.
func requestToMsgGet(req *http.Request) (*dns.Msg, error) {
values := req.URL.Query()
b64, ok := values["dns"]
if !ok {
return nil, fmt.Errorf("no 'dns' query parameter found")
}
if len(b64) != 1 {
return nil, fmt.Errorf("multiple 'dns' query values found")
}
return base64ToMsg(b64[0])
}
func toMsg(r io.ReadCloser) (*dns.Msg, error) {
buf, err := ioutil.ReadAll(r)
if err != nil {
return nil, err
}
m := new(dns.Msg)
err = m.Unpack(buf)
return m, err
}
func base64ToMsg(b64 string) (*dns.Msg, error) {
buf, err := b64Enc.DecodeString(b64)
if err != nil {
return nil, err
}
m := new(dns.Msg)
err = m.Unpack(buf)
return m, err
}
var b64Enc = base64.RawURLEncoding

52
plugin/pkg/doh/doh_test.go Normal file
View file

@ -0,0 +1,52 @@
package doh
import (
"net/http"
"testing"
"github.com/miekg/dns"
)
func TestPostRequest(t *testing.T) {
m := new(dns.Msg)
m.SetQuestion("example.org.", dns.TypeDNSKEY)
req, err := NewRequest(http.MethodPost, "https://example.org:443", m)
if err != nil {
t.Errorf("Failure to make request: %s", err)
}
m, err = RequestToMsg(req)
if err != nil {
t.Fatalf("Failure to get message from request: %s", err)
}
if x := m.Question[0].Name; x != "example.org." {
t.Errorf("Qname expected %s, got %s", "example.org.", x)
}
if x := m.Question[0].Qtype; x != dns.TypeDNSKEY {
t.Errorf("Qname expected %d, got %d", x, dns.TypeDNSKEY)
}
}
func TestGetRequest(t *testing.T) {
m := new(dns.Msg)
m.SetQuestion("example.org.", dns.TypeDNSKEY)
req, err := NewRequest(http.MethodGet, "https://example.org:443", m)
if err != nil {
t.Errorf("Failure to make request: %s", err)
}
m, err = RequestToMsg(req)
if err != nil {
t.Fatalf("Failure to get message from request: %s", err)
}
if x := m.Question[0].Name; x != "example.org." {
t.Errorf("Qname expected %s, got %s", "example.org.", x)
}
if x := m.Question[0].Qtype; x != dns.TypeDNSKEY {
t.Errorf("Qname expected %d, got %d", x, dns.TypeDNSKEY)
}
}