Names beside inside addresses

Reverse lookups (internal/names, POST /names) put a name beside each
inside address in connections, the log, quota usage, the dashboard's
quotas and the statistics' devices and blocked sources, in the web UI
and hc (--no-names to leave them out). Only inside addresses are looked
up: an inside zone's networks, and private ones outside the external
zones'. Names are cached (names.cache, 10m) and never stored;
names.resolver picks the DNS server.

Also: hc stats top devices listed each device twice; the dashboard's
quotas named the rule's ID twice.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/h_traffic.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net/http"
+	"net/netip"
 	"sort"
 	"strconv"
 	"strings"
@@ -88,6 +89,83 @@ func (s *Server) listConnections(w http.ResponseWriter, r *http.Request, p *auth
 	return nil
 }
 
+// lookupNames finds the names of the inside addresses asked about
+// (docs/configuration.md#names), waiting at most a second for lookups.
+func (s *Server) lookupNames(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
+	if err := require(p, auth.ResLog, false); err != nil {
+		return err
+	}
+	var in api.NamesInput
+	if err := decodeJSON(r, &in); err != nil {
+		return err
+	}
+	if len(in.Addresses) > maxNames {
+		return badRequest("ask for at most %d addresses at once", maxNames)
+	}
+	out := api.Names{Enabled: s.cfg.Names != nil, Names: map[string]string{}}
+	if s.cfg.Names == nil {
+		writeJSON(w, http.StatusOK, out)
+		return nil
+	}
+	inside := s.insideNetworks(s.eng.State())
+	asked := map[netip.Addr][]string{}
+	var addrs []netip.Addr
+	for _, a := range in.Addresses {
+		ad, err := netip.ParseAddr(a)
+		if err != nil || !inside(ad.Unmap()) {
+			continue
+		}
+		ad = ad.Unmap()
+		if _, ok := asked[ad]; !ok {
+			addrs = append(addrs, ad)
+		}
+		asked[ad] = append(asked[ad], a)
+	}
+	for a, n := range s.cfg.Names.Names(r.Context(), addrs, time.Second) {
+		for _, as := range asked[a] {
+			out.Names[as] = n
+		}
+	}
+	writeJSON(w, http.StatusOK, out)
+	return nil
+}
+
+// maxNames is the most addresses one POST /names may ask about.
+const maxNames = 2000
+
+// insideNetworks tells inside addresses: in a network connected to an
+// inside zone's interface, or private and not in an external zone's.
+func (s *Server) insideNetworks(st *model.State) func(netip.Addr) bool {
+	external := map[string]bool{}
+	for _, z := range st.Zones {
+		external[z.Name] = z.External
+	}
+	var in, out []netip.Prefix
+	for p, zone := range s.connected(st) {
+		if external[zone] {
+			out = append(out, p)
+		} else {
+			in = append(in, p)
+		}
+	}
+	return func(a netip.Addr) bool {
+		if a.IsLoopback() || a.IsUnspecified() || a.IsMulticast() || a.IsLinkLocalUnicast() {
+			return false
+		}
+		for _, p := range in {
+			if p.Contains(a) {
+				return true
+			}
+		}
+		for _, p := range out {
+			if p.Contains(a) {
+				return false
+			}
+		}
+		return a.IsPrivate()
+	}
+}
+
 // closeConnections deletes tracking entries: the rules check those
 // connections again with their next packet.
 func (s *Server) closeConnections(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {