split cert func to related packages

server/dns/const.go

@@ -0,0 +1,6 @@
+package dns
+
+import "time"
+
+// DnsLookupCacheTimeout specifies the timeout for the DNS lookup cache.
+var DnsLookupCacheTimeout = 15 * time.Minute

server/dns/dns.go

@@ -0,0 +1,56 @@
+package dns
+
+import (
+	"net"
+	"strings"
+
+	"codeberg.org/codeberg/pages/server/cache"
+)
+
+// GetTargetFromDNS searches for CNAME or TXT entries on the request domain ending with MainDomainSuffix.
+// If everything is fine, it returns the target data.
+func GetTargetFromDNS(domain, mainDomainSuffix string, dnsLookupCache cache.SetGetKey) (targetOwner, targetRepo, targetBranch string) {
+	// Get CNAME or TXT
+	var cname string
+	var err error
+	if cachedName, ok := dnsLookupCache.Get(domain); ok {
+		cname = cachedName.(string)
+	} else {
+		cname, err = net.LookupCNAME(domain)
+		cname = strings.TrimSuffix(cname, ".")
+		if err != nil || !strings.HasSuffix(cname, mainDomainSuffix) {
+			cname = ""
+			// TODO: check if the A record matches!
+			names, err := net.LookupTXT(domain)
+			if err == nil {
+				for _, name := range names {
+					name = strings.TrimSuffix(name, ".")
+					if strings.HasSuffix(name, mainDomainSuffix) {
+						cname = name
+						break
+					}
+				}
+			}
+		}
+		_ = dnsLookupCache.Set(domain, cname, DnsLookupCacheTimeout)
+	}
+	if cname == "" {
+		return
+	}
+	cnameParts := strings.Split(strings.TrimSuffix(cname, mainDomainSuffix), ".")
+	targetOwner = cnameParts[len(cnameParts)-1]
+	if len(cnameParts) > 1 {
+		targetRepo = cnameParts[len(cnameParts)-2]
+	}
+	if len(cnameParts) > 2 {
+		targetBranch = cnameParts[len(cnameParts)-3]
+	}
+	if targetRepo == "" {
+		targetRepo = "pages"
+	}
+	if targetBranch == "" && targetRepo != "pages" {
+		targetBranch = "pages"
+	}
+	// if targetBranch is still empty, the caller must find the default branch
+	return
+}