ba1efee4f1
Every plugin needs to deal with EDNS0 and should call Scrub to make a message fit the client's buffer. Move this functionality into the server and wrapping the ResponseWriter into a ScrubWriter that handles these bits for us. Result: Less code and faster, because multiple chained plugins could all be calling scrub and SizeAndDo - now there is just one place. Most tests in file/* and dnssec/* needed adjusting because in those unit tests you don't see OPT RRs anymore. The DNSSEC signer was also looking at the returned OPT RR to see if it needed to sign - as those are now added by the server (and thus later), this needed to change slightly. Scrub itself still exist (for backward compat reasons), but has been made a noop. Scrub has been renamed to scrub as it should not be used by external plugins. Fixes: #2010 Signed-off-by: Miek Gieben <miek@miek.nl>
103 lines
2.1 KiB
Go
103 lines
2.1 KiB
Go
package proxy
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import (
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"context"
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"net"
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"time"
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"github.com/coredns/coredns/request"
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"github.com/miekg/dns"
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)
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type dnsEx struct {
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Timeout time.Duration
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Options
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}
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// Options define the options understood by dns.Exchange.
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type Options struct {
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ForceTCP bool // If true use TCP for upstream no matter what
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}
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func newDNSEx() *dnsEx {
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return newDNSExWithOption(Options{})
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}
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func newDNSExWithOption(opt Options) *dnsEx {
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return &dnsEx{Timeout: defaultTimeout * time.Second, Options: opt}
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}
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func (d *dnsEx) Transport() string {
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if d.Options.ForceTCP {
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return "tcp"
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}
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// The protocol will be determined by `state.Proto()` during Exchange.
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return ""
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}
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func (d *dnsEx) Protocol() string { return "dns" }
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func (d *dnsEx) OnShutdown(p *Proxy) error { return nil }
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func (d *dnsEx) OnStartup(p *Proxy) error { return nil }
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// Exchange implements the Exchanger interface.
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func (d *dnsEx) Exchange(ctx context.Context, addr string, state request.Request) (*dns.Msg, error) {
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proto := state.Proto()
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if d.Options.ForceTCP {
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proto = "tcp"
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}
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co, err := net.DialTimeout(proto, addr, d.Timeout)
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if err != nil {
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return nil, err
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}
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reply, _, err := d.ExchangeConn(state.Req, co)
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co.Close()
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if reply != nil && reply.Truncated {
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// Suppress proxy error for truncated responses
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err = nil
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}
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if err != nil {
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return nil, err
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}
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reply.Id = state.Req.Id
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return reply, nil
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}
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func (d *dnsEx) ExchangeConn(m *dns.Msg, co net.Conn) (*dns.Msg, time.Duration, error) {
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start := time.Now()
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r, err := exchange(m, co)
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rtt := time.Since(start)
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return r, rtt, err
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}
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func exchange(m *dns.Msg, co net.Conn) (*dns.Msg, error) {
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opt := m.IsEdns0()
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udpsize := uint16(dns.MinMsgSize)
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// If EDNS0 is used use that for size.
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if opt != nil && opt.UDPSize() >= dns.MinMsgSize {
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udpsize = opt.UDPSize()
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}
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dnsco := &dns.Conn{Conn: co, UDPSize: udpsize}
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writeDeadline := time.Now().Add(defaultTimeout)
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dnsco.SetWriteDeadline(writeDeadline)
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dnsco.WriteMsg(m)
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readDeadline := time.Now().Add(defaultTimeout)
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co.SetReadDeadline(readDeadline)
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r, err := dnsco.ReadMsg()
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dnsco.Close()
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if r == nil {
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return nil, err
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}
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return r, err
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}
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