78 lines
1.6 KiB
Go
78 lines
1.6 KiB
Go
package dns
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import (
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"errors"
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"net"
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"strings"
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"time"
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"github.com/patrickmn/go-cache"
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)
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const (
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// TXT record name that lookupRepoTXT will try to lookup.
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TxtRepoRecord = "_rio-pages."
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// The key that the TXT record will have to start with, e.g.
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// "repo=some-random-repo".
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TxtRepoKey = "repo="
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)
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var (
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// Cache for CNAME resolution results.
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cnameCache = cache.New(1*time.Hour, 1*time.Hour)
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// Cache for TXT resolution results.
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txtRepoCache = cache.New(1*time.Hour, 1*time.Hour)
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)
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// Query the domain for the a repository redirect.
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// Returns the new repository name or "", if we could not
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// resolve a repository redirect.
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func LookupRepoTXT(domain string) (string, error) {
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repoLookup, found := txtRepoCache.Get(domain)
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if found {
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return repoLookup.(string), nil
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}
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txts, err := net.LookupTXT("_rio-pages." + domain)
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if err != nil {
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return "", err
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}
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repo := ""
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for _, txt := range txts {
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if !strings.HasPrefix(txt, TxtRepoKey) {
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continue
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}
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repo = strings.TrimPrefix(txt, TxtRepoKey)
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break
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}
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txtRepoCache.Set(domain, repo, cache.DefaultExpiration)
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return repo, nil
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}
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// Query the domain for a CNAME record. Returns the resolved
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// CNAME or "", if no CNAME could be queried.
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func LookupCNAME(domain string) (string, error) {
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cname, found := cnameCache.Get(domain)
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if found {
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if cname == "" {
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return "", errors.New("Previous request failure")
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}
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return cname.(string), nil
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}
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cname, err := net.LookupCNAME(domain)
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if err == nil {
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cnameCache.Set(domain, cname, cache.DefaultExpiration)
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return cname.(string), nil
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}
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cnameCache.Set(domain, "", cache.DefaultExpiration)
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return "", err
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}
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