67 lines
1.8 KiB
Go
67 lines
1.8 KiB
Go
package dns
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import (
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"net"
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"strings"
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"time"
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"github.com/hashicorp/golang-lru/v2/expirable"
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)
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const (
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lookupCacheValidity = 30 * time.Second
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defaultPagesRepo = "pages"
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)
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// TODO(#316): refactor to not use global variables
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var lookupCache *expirable.LRU[string, string] = expirable.NewLRU[string, string](4096, nil, lookupCacheValidity)
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// GetTargetFromDNS searches for CNAME or TXT entries on the request domain ending with MainDomainSuffix.
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// If everything is fine, it returns the target data.
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func GetTargetFromDNS(domain, mainDomainSuffix, firstDefaultBranch string) (targetOwner, targetRepo, targetBranch string) {
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// Get CNAME or TXT
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var cname string
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var err error
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if entry, ok := lookupCache.Get(domain); ok {
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cname = entry
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} else {
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cname, err = net.LookupCNAME(domain)
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cname = strings.TrimSuffix(cname, ".")
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if err != nil || !strings.HasSuffix(cname, mainDomainSuffix) {
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cname = ""
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// TODO: check if the A record matches!
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names, err := net.LookupTXT(domain)
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if err == nil {
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for _, name := range names {
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name = strings.TrimSuffix(strings.TrimSpace(name), ".")
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if strings.HasSuffix(name, mainDomainSuffix) {
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cname = name
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break
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}
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}
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}
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}
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_ = lookupCache.Add(domain, cname)
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}
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if cname == "" {
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return
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}
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cnameParts := strings.Split(strings.TrimSuffix(cname, mainDomainSuffix), ".")
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targetOwner = cnameParts[len(cnameParts)-1]
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if len(cnameParts) > 1 {
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targetRepo = cnameParts[len(cnameParts)-2]
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}
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if len(cnameParts) > 2 {
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targetBranch = cnameParts[len(cnameParts)-3]
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}
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if targetRepo == "" {
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targetRepo = defaultPagesRepo
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}
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if targetBranch == "" && targetRepo != defaultPagesRepo {
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targetBranch = firstDefaultBranch
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}
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// if targetBranch is still empty, the caller must find the default branch
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return
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}
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