WIP

peer/hosts.go

@@ -14,10 +14,18 @@ import (
 
 const (
 	hostsFile  = "/etc/hosts"
-	hostsBegin = "# BEGIN vppn "
-	hostsEnd   = "# END vppn "
+	hostsBegin = "# BEGIN vppn"
+	hostsEnd   = "# END vppn"
 )
 
+// hostMarkers returns the begin/end marker lines that delimit the managed
+// section for localDomain. The domain is wrapped in parentheses so one domain's
+// marker can never be a prefix of another's (e.g. "net" vs "net2") when
+// multiple vppn instances share /etc/hosts.
+func hostMarkers(localDomain string) (begin, end string) {
+	return hostsBegin + "(" + localDomain + ")", hostsEnd + "(" + localDomain + ")"
+}
+
 // updateHosts rewrites the managed vppn section in /etc/hosts using the
 // current peersByIP map. Peers without a Name are skipped.
 func (a *App) updateHosts() {
@@ -36,8 +44,7 @@ func updateHosts(hostsPath, localDomain string, peers map[netip.Addr]*Peer) erro
 	}
 	defer lockFile.Close()
 
-	begin := hostsBegin + localDomain
-	end := hostsEnd + localDomain
+	begin, end := hostMarkers(localDomain)
 
 	info, err := os.Stat(hostsPath)
 	if err != nil {