clash/dns/client.go

88 lines
1.7 KiB
Go

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