95 lines
1.9 KiB
Go
95 lines
1.9 KiB
Go
package resolver
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"net"
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"net/http"
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"net/url"
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"time"
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)
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var _ net.Conn = &dohConn{}
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type dohConn struct {
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query, resp *bytes.Buffer
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do func() error
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}
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func newDoHConn(ctx context.Context, client *http.Client, addr string) (*dohConn, error) {
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c := &dohConn{
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query: &bytes.Buffer{},
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resp: &bytes.Buffer{},
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}
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url, err := url.Parse(addr)
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if err != nil {
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return nil, err
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}
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// RFC 8484
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url.Path = "/dns-query"
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c.do = func() error {
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if c.query.Len() <= 2 || c.resp.Len() > 0 {
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return nil
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}
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// Skip length header
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c.query.Next(2)
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req, err := http.NewRequestWithContext(ctx, http.MethodPost, url.String(), c.query)
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if err != nil {
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return err
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}
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req.Header.Set("content-type", "application/dns-message")
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req.Header.Set("accept", "application/dns-message")
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resp, err := client.Do(req)
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if err != nil {
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return err
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}
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defer resp.Body.Close()
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respBody, err := io.ReadAll(resp.Body)
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if err != nil {
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return err
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}
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if resp.StatusCode != http.StatusOK {
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return fmt.Errorf("server return %d: %s", resp.StatusCode, respBody)
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}
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// Add length header
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l := uint16(len(respBody))
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_, err = c.resp.Write([]byte{uint8(l >> 8), uint8(l & ((1 << 8) - 1))})
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if err != nil {
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return err
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}
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_, err = c.resp.Write(respBody)
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return err
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}
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return c, nil
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}
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func (c *dohConn) Close() error { return nil }
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func (c *dohConn) LocalAddr() net.Addr { return nil }
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func (c *dohConn) RemoteAddr() net.Addr { return nil }
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func (c *dohConn) SetDeadline(time.Time) error { return nil }
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func (c *dohConn) SetReadDeadline(time.Time) error { return nil }
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func (c *dohConn) SetWriteDeadline(time.Time) error { return nil }
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func (c *dohConn) Write(b []byte) (int, error) { return c.query.Write(b) }
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func (c *dohConn) Read(b []byte) (int, error) {
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if err := c.do(); err != nil {
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return 0, err
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}
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return c.resp.Read(b)
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}
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