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https://github.com/Control-D-Inc/ctrld.git
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b471adfb09
In split mode, the code must check for ipv6 availability to return the correct network stack. Otherwise, we may end up using "tcp6-tls" even though the upstream IP is an ipv4.
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(bootstrapDNS, "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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