95 lines
2 KiB
Go
95 lines
2 KiB
Go
package dns
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import (
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"bytes"
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"context"
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"crypto/tls"
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"io/ioutil"
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"net"
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"net/http"
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"github.com/Dreamacro/clash/component/dialer"
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D "github.com/miekg/dns"
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)
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const (
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// dotMimeType is the DoH mimetype that should be used.
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dotMimeType = "application/dns-message"
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)
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type dohClient struct {
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url string
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transport *http.Transport
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}
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func (dc *dohClient) Exchange(m *D.Msg) (msg *D.Msg, err error) {
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return dc.ExchangeContext(context.Background(), m)
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}
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func (dc *dohClient) ExchangeContext(ctx context.Context, m *D.Msg) (msg *D.Msg, err error) {
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req, err := dc.newRequest(m)
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if err != nil {
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return nil, err
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}
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req = req.WithContext(ctx)
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return dc.doRequest(req)
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}
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// newRequest returns a new DoH request given a dns.Msg.
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func (dc *dohClient) newRequest(m *D.Msg) (*http.Request, error) {
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buf, err := m.Pack()
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if err != nil {
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return nil, err
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}
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req, err := http.NewRequest(http.MethodPost, dc.url, bytes.NewReader(buf))
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if err != nil {
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return req, err
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}
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req.Header.Set("content-type", dotMimeType)
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req.Header.Set("accept", dotMimeType)
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return req, nil
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}
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func (dc *dohClient) doRequest(req *http.Request) (msg *D.Msg, err error) {
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client := &http.Client{Transport: dc.transport}
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resp, err := client.Do(req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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buf, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return nil, err
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}
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msg = &D.Msg{}
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err = msg.Unpack(buf)
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return msg, err
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}
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func newDoHClient(url string, r *Resolver) *dohClient {
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return &dohClient{
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url: url,
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transport: &http.Transport{
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TLSClientConfig: &tls.Config{ClientSessionCache: globalSessionCache},
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ForceAttemptHTTP2: true,
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DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
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host, port, err := net.SplitHostPort(addr)
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if err != nil {
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return nil, err
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}
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ip, err := r.ResolveIPv4(host)
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if err != nil {
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return nil, err
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}
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return dialer.DialContext(ctx, "tcp4", net.JoinHostPort(ip.String(), port))
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},
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},
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}
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}
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