From 2b9f3319803e74b81f16b5216ab99e70acad24ea Mon Sep 17 00:00:00 2001
From: Pedro Maia Costa <550684+pnmcosta@users.noreply.github.com>
Date: Fri, 11 Jul 2025 10:29:10 +0100
Subject: [PATCH] always suffix ephemeral peer name (#4138)

---
 management/server/peer.go | 43 +++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/management/server/peer.go b/management/server/peer.go
index a60513b38..21a9579fc 100644
--- a/management/server/peer.go
+++ b/management/server/peer.go
@@ -236,11 +236,23 @@ func (am *DefaultAccountManager) UpdatePeer(ctx context.Context, accountID, user
 
 		if peer.Name != update.Name {
 			var newLabel string
-			newLabel, err = getPeerIPDNSLabel(ctx, transaction, peer.IP, accountID, update.Name)
+
+			newLabel, err = nbdns.GetParsedDomainLabel(update.Name)
 			if err != nil {
-				return fmt.Errorf("failed to get free DNS label: %w", err)
+				newLabel = ""
+			} else {
+				_, err := transaction.GetPeerIdByLabel(ctx, store.LockingStrengthNone, accountID, update.Name)
+				if err == nil {
+					newLabel = ""
+				}
 			}
 
+			if newLabel == "" {
+				newLabel, err = getPeerIPDNSLabel(peer.IP, update.Name)
+				if err != nil {
+					return fmt.Errorf("failed to get free DNS label: %w", err)
+				}
+			}
 			peer.Name = update.Name
 			peer.DNSLabel = newLabel
 			peerLabelChanged = true
@@ -472,6 +484,7 @@ func (am *DefaultAccountManager) AddPeer(ctx context.Context, setupKey, userID s
 	var groupsToAdd []string
 	var allowExtraDNSLabels bool
 	var accountID string
+	var isEphemeral bool
 	if addedByUser {
 		user, err := am.Store.GetUserByUserID(ctx, store.LockingStrengthNone, userID)
 		if err != nil {
@@ -501,7 +514,7 @@ func (am *DefaultAccountManager) AddPeer(ctx context.Context, setupKey, userID s
 		setupKeyName = sk.Name
 		allowExtraDNSLabels = sk.AllowExtraDNSLabels
 		accountID = sk.AccountID
-
+		isEphemeral = sk.Ephemeral
 		if !sk.AllowExtraDNSLabels && len(peer.ExtraDNSLabels) > 0 {
 			return nil, nil, nil, status.Errorf(status.PreconditionFailed, "couldn't add peer: setup key doesn't allow extra DNS labels")
 		}
@@ -573,11 +586,17 @@ func (am *DefaultAccountManager) AddPeer(ctx context.Context, setupKey, userID s
 		}
 
 		var freeLabel string
-		freeLabel, err = getPeerIPDNSLabel(ctx, am.Store, freeIP, accountID, peer.Meta.Hostname)
-		if err != nil {
-			return nil, nil, nil, fmt.Errorf("failed to get free DNS label: %w", err)
+		if isEphemeral || attempt > 1 {
+			freeLabel, err = getPeerIPDNSLabel(freeIP, peer.Meta.Hostname)
+			if err != nil {
+				return nil, nil, nil, fmt.Errorf("failed to get free DNS label: %w", err)
+			}
+		} else {
+			freeLabel, err = nbdns.GetParsedDomainLabel(peer.Meta.Hostname)
+			if err != nil {
+				return nil, nil, nil, fmt.Errorf("failed to get free DNS label: %w", err)
+			}
 		}
-
 		newPeer.DNSLabel = freeLabel
 		newPeer.IP = freeIP
 
@@ -647,7 +666,7 @@ func (am *DefaultAccountManager) AddPeer(ctx context.Context, setupKey, userID s
 		if isUniqueConstraintError(err) {
 			unlock()
 			unlock = nil
-			log.WithContext(ctx).Debugf("Failed to add peer in attempt %d, retrying: %v", attempt, err)
+			log.WithContext(ctx).WithFields(log.Fields{"dns_label": freeLabel, "ip": freeIP}).Tracef("Failed to add peer in attempt %d, retrying: %v", attempt, err)
 			continue
 		}
 
@@ -681,7 +700,7 @@ func (am *DefaultAccountManager) AddPeer(ctx context.Context, setupKey, userID s
 	return am.getValidatedPeerWithMap(ctx, false, accountID, newPeer)
 }
 
-func getPeerIPDNSLabel(ctx context.Context, tx store.Store, ip net.IP, accountID, peerHostName string) (string, error) {
+func getPeerIPDNSLabel(ip net.IP, peerHostName string) (string, error) {
 	ip = ip.To4()
 
 	dnsName, err := nbdns.GetParsedDomainLabel(peerHostName)
@@ -689,12 +708,6 @@ func getPeerIPDNSLabel(ctx context.Context, tx store.Store, ip net.IP, accountID
 		return "", fmt.Errorf("failed to parse peer host name %s: %w", peerHostName, err)
 	}
 
-	_, err = tx.GetPeerIdByLabel(ctx, store.LockingStrengthNone, accountID, dnsName)
-	if err != nil {
-		//nolint:nilerr
-		return dnsName, nil
-	}
-
 	return fmt.Sprintf("%s-%d-%d", dnsName, ip[2], ip[3]), nil
 }