37 lines
875 B
Go
37 lines
875 B
Go
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package upstream
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import (
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"github.com/miekg/dns"
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"golang.org/x/net/context"
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"time"
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)
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// DnsUpstream is a very simple upstream implementation for plain DNS
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type DnsUpstream struct {
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nameServer string // IP:port
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timeout time.Duration // Max read and write timeout
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}
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// NewDnsUpstream creates a new plain-DNS upstream
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func NewDnsUpstream(nameServer string) (Upstream, error) {
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return &DnsUpstream{nameServer: nameServer, timeout: defaultTimeout}, nil
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}
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// Exchange provides an implementation for the Upstream interface
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func (u *DnsUpstream) Exchange(ctx context.Context, query *dns.Msg) (*dns.Msg, error) {
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dnsClient := &dns.Client{
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ReadTimeout: u.timeout,
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WriteTimeout: u.timeout,
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}
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resp, _, err := dnsClient.Exchange(query, u.nameServer)
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if err != nil {
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resp = &dns.Msg{}
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resp.SetRcode(resp, dns.RcodeServerFailure)
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}
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return resp, err
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}
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