87 lines
1.7 KiB
Go
87 lines
1.7 KiB
Go
package dns
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import (
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"context"
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"crypto/tls"
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"fmt"
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"net"
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"strings"
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"github.com/Dreamacro/clash/component/dialer"
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"github.com/Dreamacro/clash/component/resolver"
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D "github.com/miekg/dns"
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)
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type client struct {
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*D.Client
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r *Resolver
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port string
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host string
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iface string
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}
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func (c *client) Exchange(m *D.Msg) (*D.Msg, error) {
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return c.ExchangeContext(context.Background(), m)
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}
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func (c *client) ExchangeContext(ctx context.Context, m *D.Msg) (*D.Msg, error) {
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var (
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ip net.IP
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err error
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)
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if c.r == nil {
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// a default ip dns
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if ip = net.ParseIP(c.host); ip == nil {
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return nil, fmt.Errorf("dns %s not a valid ip", c.host)
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}
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} else {
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if ip, err = resolver.ResolveIPWithResolver(c.host, c.r); err != nil {
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return nil, fmt.Errorf("use default dns resolve failed: %w", err)
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}
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}
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network := "udp"
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if strings.HasPrefix(c.Client.Net, "tcp") {
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network = "tcp"
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}
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options := []dialer.Option{}
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if c.iface != "" {
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options = append(options, dialer.WithInterface(c.iface))
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}
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conn, err := dialer.DialContext(ctx, network, net.JoinHostPort(ip.String(), c.port), options...)
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if err != nil {
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return nil, err
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}
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defer conn.Close()
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// miekg/dns ExchangeContext doesn't respond to context cancel.
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// this is a workaround
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type result struct {
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msg *D.Msg
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err error
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}
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ch := make(chan result, 1)
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go func() {
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if strings.HasSuffix(c.Client.Net, "tls") {
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conn = tls.Client(conn, c.Client.TLSConfig)
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}
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msg, _, err := c.Client.ExchangeWithConn(m, &D.Conn{
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Conn: conn,
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UDPSize: c.Client.UDPSize,
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TsigSecret: c.Client.TsigSecret,
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TsigProvider: c.Client.TsigProvider,
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})
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ch <- result{msg, err}
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}()
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select {
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case <-ctx.Done():
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return nil, ctx.Err()
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case ret := <-ch:
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return ret.msg, ret.err
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}
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}
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