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71029cea2d
This updates all source files to use a new standard header for copyright and license declaration. Notably, copyright no longer includes a date, and we now use the standard SPDX-License-Identifier header. This commit was done almost entirely mechanically with perl, and then some minimal manual fixes. Updates #6865 Signed-off-by: Will Norris <will@tailscale.com>
101 lines
2.5 KiB
Go
101 lines
2.5 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package tsdial
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import (
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"bytes"
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"context"
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"errors"
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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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"time"
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"tailscale.com/net/dnscache"
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)
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// dohConn is a net.PacketConn suitable for returning from
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// net.Dialer.Dial to send DNS queries over PeerAPI to exit nodes'
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// ExitDNS DoH proxy service.
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type dohConn struct {
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ctx context.Context
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baseURL string
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hc *http.Client // if nil, default is used
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dnsCache *dnscache.MessageCache
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rbuf bytes.Buffer
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}
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var (
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_ net.Conn = (*dohConn)(nil)
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_ net.PacketConn = (*dohConn)(nil) // be a PacketConn to change net.Resolver semantics
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)
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func (*dohConn) Close() error { return nil }
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func (*dohConn) LocalAddr() net.Addr { return todoAddr{} }
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func (*dohConn) RemoteAddr() net.Addr { return todoAddr{} }
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func (*dohConn) SetDeadline(t time.Time) error { return nil }
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func (*dohConn) SetReadDeadline(t time.Time) error { return nil }
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func (*dohConn) SetWriteDeadline(t time.Time) error { return nil }
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func (c *dohConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
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return c.Write(p)
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}
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func (c *dohConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
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n, err = c.Read(p)
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return n, todoAddr{}, err
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}
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func (c *dohConn) Read(p []byte) (n int, err error) {
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return c.rbuf.Read(p)
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}
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func (c *dohConn) Write(packet []byte) (n int, err error) {
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if c.dnsCache != nil {
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err := c.dnsCache.ReplyFromCache(&c.rbuf, packet)
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if err == nil {
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// Cache hit.
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// TODO(bradfitz): add clientmetric
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return len(packet), nil
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}
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c.rbuf.Reset()
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}
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req, err := http.NewRequestWithContext(c.ctx, "POST", c.baseURL, bytes.NewReader(packet))
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if err != nil {
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return 0, err
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}
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const dohType = "application/dns-message"
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req.Header.Set("Content-Type", dohType)
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hc := c.hc
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if hc == nil {
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hc = http.DefaultClient
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}
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hres, err := hc.Do(req)
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if err != nil {
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return 0, err
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}
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defer hres.Body.Close()
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if hres.StatusCode != 200 {
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return 0, errors.New(hres.Status)
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}
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if ct := hres.Header.Get("Content-Type"); ct != dohType {
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return 0, fmt.Errorf("unexpected response Content-Type %q", ct)
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}
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_, err = io.Copy(&c.rbuf, hres.Body)
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if err != nil {
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return 0, err
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}
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if c.dnsCache != nil {
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c.dnsCache.AddCacheEntry(packet, c.rbuf.Bytes())
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}
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return len(packet), nil
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}
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type todoAddr struct{}
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func (todoAddr) Network() string { return "unused" }
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func (todoAddr) String() string { return "unused-todoAddr" }
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