41 lines
687 B
Go
41 lines
687 B
Go
package netdns
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import (
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"context"
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"fmt"
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"net"
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"sort"
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"strings"
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)
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type NetMXResolver struct{}
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func NewNetMXResolver() *NetMXResolver {
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return &NetMXResolver{}
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}
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func (r *NetMXResolver) LookupMX(ctx context.Context, domain string) ([]string, error) {
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mxs, err := net.DefaultResolver.LookupMX(ctx, domain)
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if err != nil {
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return nil, fmt.Errorf("lookup mx for %s: %w", domain, err)
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}
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sort.Slice(mxs, func(i, j int) bool {
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return mxs[i].Pref < mxs[j].Pref
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})
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var hosts []string
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for _, mx := range mxs {
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h := strings.TrimSuffix(mx.Host, ".")
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if h != "" {
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hosts = append(hosts, h)
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}
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}
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if len(hosts) == 0 {
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hosts = []string{domain}
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}
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return hosts, nil
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}
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