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https://github.com/Control-D-Inc/ctrld.git
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56f9c72569
Since the OS resolver only returns response with NOERROR first, it's safe to use ControlD public DNS in parallel with system DNS. Local domains would resolve only though local resolvers, because public ones will return NXDOMAIN response.
44 lines
1.1 KiB
Go
44 lines
1.1 KiB
Go
package ctrld
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import (
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"context"
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"crypto/tls"
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"net"
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"github.com/miekg/dns"
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)
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type dotResolver struct {
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uc *UpstreamConfig
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}
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func (r *dotResolver) Resolve(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
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// The dialer is used to prevent bootstrapping cycle.
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// If r.endpoint is set to dns.controld.dev, we need to resolve
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// dns.controld.dev first. By using a dialer with custom resolver,
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// we ensure that we can always resolve the bootstrap domain
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// regardless of the machine DNS status.
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dialer := newDialer(net.JoinHostPort(controldBootstrapDns, "53"))
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dnsTyp := uint16(0)
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if msg != nil && len(msg.Question) > 0 {
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dnsTyp = msg.Question[0].Qtype
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}
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tcpNet, _ := r.uc.netForDNSType(dnsTyp)
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dnsClient := &dns.Client{
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Net: tcpNet,
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Dialer: dialer,
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TLSConfig: &tls.Config{RootCAs: r.uc.certPool},
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}
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endpoint := r.uc.Endpoint
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if r.uc.BootstrapIP != "" {
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dnsClient.TLSConfig.ServerName = r.uc.Domain
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dnsClient.Net = "tcp-tls"
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_, port, _ := net.SplitHostPort(endpoint)
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endpoint = net.JoinHostPort(r.uc.BootstrapIP, port)
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}
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answer, _, err := dnsClient.ExchangeContext(ctx, msg, endpoint)
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return answer, err
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}
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