Wake: a target may list several broadcast addresses

Config keeps broadcast (one) and adds broadcasts (a list); exactly one must be present. Wake.Addresses() returns Broadcast then Broadcasts; checkWake errors on both-set, neither-or-empty, and non-host:port entries. Waker sends to every address in order, logging/past a failure so one dead address does not stop the others, and returns false only when none could be sent. Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)
2026-09-25 13:45:39 -07:00
parent 4e1dd03d07
commit 8018f67031
6 changed files with 146 additions and 14 deletions
@@ -7,11 +7,24 @@ import (
 )

 // Wake is the magic-wake pattern sent to a host to rouse it: its MAC, the
-// broadcast address to aim at, and how long to wait for the answer.
+// broadcast address(s) to aim at, and how long to wait for the answer. A host
+// that roams between networks names several, so Broadcast (one) and Broadcasts
+// (a list) are alternatives: exactly one must be set.
 type Wake struct {
-	MAC       string   `toml:"mac"`
-	Broadcast string   `toml:"broadcast"`
-	Wait      Duration `toml:"wait"`
+	MAC        string   `toml:"mac"`
+	Broadcast  string   `toml:"broadcast"`
+	Broadcasts []string `toml:"broadcasts"`
+	Wait       Duration `toml:"wait"`
+}
+
+// Addresses is Broadcast (when set) followed by Broadcasts: the ordered list to
+// send wake packets to, never empty for a parsed config.
+func (w *Wake) Addresses() []string {
+	addrs := make([]string, 0, 1+len(w.Broadcasts))
+	if w.Broadcast != "" {
+		addrs = append(addrs, w.Broadcast)
+	}
+	return append(addrs, w.Broadcasts...)
 }

 const (
@@ -40,8 +53,19 @@ func (c *Config) checkWake() *Error {
 			return &Error{Field: wakeField + ".mac", Msg: "must be a MAC address"}
 		}

-		if _, _, err := net.SplitHostPort(w.Broadcast); err != nil || w.Broadcast == "" {
+		broadcastSet := w.Broadcast != ""
+		broadcastsSet := len(w.Broadcasts) > 0
+		switch {
+		case broadcastSet && broadcastsSet:
+			return &Error{Field: wakeField + ".broadcasts", Msg: "choose broadcast or broadcasts, not both"}
+		case !broadcastSet && !broadcastsSet:
 			return &Error{Field: wakeField + ".broadcast", Msg: "must be a non-empty host:port"}
+		default:
+			for _, a := range w.Broadcasts {
+				if _, _, err := net.SplitHostPort(a); err != nil || a == "" {
+					return &Error{Field: wakeField + ".broadcasts", Msg: "must be a non-empty host:port"}
+				}
+			}
 		}

 		if w.Wait.Duration == 0 {
@@ -0,0 +1,73 @@
+package wake_test
+
+import (
+	"net"
+	"testing"
+	"time"
+
+	"git.wntrmute.dev/kyle/crossbar/internal/wake"
+)
+
+// listener returns a UDP socket on 127.0.0.1 and a channel that gets one value per datagram.
+func listener(t *testing.T) (string, <-chan []byte) {
+	t.Helper()
+	pc, err := net.ListenPacket("udp4", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { pc.Close() })
+	got := make(chan []byte, 4)
+	go func() {
+		buf := make([]byte, 256)
+		for {
+			n, _, err := pc.ReadFrom(buf)
+			if err != nil {
+				return
+			}
+			b := make([]byte, n)
+			copy(b, buf[:n])
+			got <- b
+		}
+	}()
+	return pc.LocalAddr().String(), got
+}
+
+func expectPacket(t *testing.T, name string, got <-chan []byte) {
+	t.Helper()
+	select {
+	case b := <-got:
+		if len(b) != 102 {
+			t.Errorf("%s: got %d bytes, want a 102-byte magic packet", name, len(b))
+		}
+	case <-time.After(2 * time.Second):
+		t.Errorf("%s: no packet within two seconds", name)
+	}
+}
+
+// A target may name several broadcast addresses (a host that roams between two networks): the
+// packet goes to every one of them, and one address that cannot be resolved does not stop the
+// others.
+func TestWakeSendsToEveryBroadcast(t *testing.T) {
+	a, gotA := listener(t)
+	b, gotB := listener(t)
+	h := &fakeHealth{after: 1 << 30} // never healthy
+	w := wake.New(map[string]wake.Target{"titan": {MAC: "aa:bb:cc:dd:ee:ff", Broadcasts: []string{a, "256.1.1.1:9", b}, Wait: 300 * time.Millisecond}}, h)
+	w.PollEvery(20 * time.Millisecond)
+	if w.Wake(t.Context(), "titan") {
+		t.Errorf("Wake must report false when the host never comes up")
+	}
+	expectPacket(t, "first address", gotA)
+	expectPacket(t, "third address, after an unresolvable second", gotB)
+}
+
+// The single-address form keeps working, alone or together with the list.
+func TestWakeBroadcastAndBroadcastsCombine(t *testing.T) {
+	a, gotA := listener(t)
+	b, gotB := listener(t)
+	h := &fakeHealth{after: 1 << 30} // never healthy
+	w := wake.New(map[string]wake.Target{"titan": {MAC: "aa:bb:cc:dd:ee:ff", Broadcast: a, Broadcasts: []string{b}, Wait: 300 * time.Millisecond}}, h)
+	w.PollEvery(20 * time.Millisecond)
+	w.Wake(t.Context(), "titan")
+	expectPacket(t, "Broadcast", gotA)
+	expectPacket(t, "Broadcasts[0]", gotB)
+}
@@ -7,15 +7,25 @@ package wake
 import (
 	"context"
 	"fmt"
+	"log/slog"
 	"net"
 	"sync"
 	"time"
 )

-// Target describes how to wake one named host.
+// log reports a broadcast that fails to resolve or send. Wake continues past
+// such failures (rule: one dead address must not stop the others), so this is
+// the only place the package logs; the address and error are not request data.
+var log = slog.New(slog.Default().Handler())
+
+// Target describes how to wake one named host. Broadcast is the single-address
+// form (as before); Broadcasts names more than one (a host that roams between
+// networks). Wake sends to Broadcast (if set) and then each of Broadcasts.
 type Target struct {
-	MAC, Broadcast string // MAC "aa:bb:cc:dd:ee:ff" (any separator, any case); Broadcast "host:port"
-	Wait           time.Duration
+	MAC        string
+	Broadcast  string
+	Broadcasts []string
+	Wait       time.Duration
 }

 // Health reports whether a named host is currently healthy. Implementations must
@@ -67,6 +77,26 @@ func Send(mac, broadcast string) error {
 	return nil
 }

+// sendAll emits one magic packet for mac to broadcast (if non-empty) and then
+// to each address in the rest, in order. An address that fails to resolve or
+// send is logged and does not stop the others; it reports whether at least one
+// packet went out.
+func sendAll(mac, broadcast string, rest []string) bool {
+	addrs := append([]string{broadcast}, rest...)
+	sent := false
+	for _, addr := range addrs {
+		if addr == "" {
+			continue
+		}
+		if err := Send(mac, addr); err != nil {
+			log.Error("wake broadcast failed", "addr", addr, "err", err)
+			continue
+		}
+		sent = true
+	}
+	return sent
+}
+
 // Waker wakes named hosts at most once per wait window and waits for the health
 // table to report them healthy. It is safe for concurrent Wake calls.
 type Waker struct {
@@ -95,10 +125,13 @@ func (w *Waker) PollEvery(d time.Duration) {
 	w.mu.Unlock()
 }

-// Wake sends a magic packet for host if none was sent in the last Wait, then
-// polls health until the host is healthy, the wait elapses, or ctx is done. It
-// returns true only when the host becomes healthy, and false for an unknown
-// host, on timeout, or when ctx ends first.
+// Wake sends a magic packet for host to every broadcast address — Broadcast
+// (if set) then each of Broadcasts, in order — if none was sent in the last
+// Wait, then polls health until the host is healthy, the wait elapses, or ctx is
+// done. A broadcast that fails to resolve or send is logged and does not stop
+// the others; Wake returns true only when the host becomes healthy, and false
+// for an unknown host, on timeout, when ctx ends first, or when no address
+// could be sent to.
 func (w *Waker) Wake(ctx context.Context, host string) bool {
 	w.mu.Lock()
 	target, ok := w.targets[host]
@@ -110,7 +143,7 @@ func (w *Waker) Wake(ctx context.Context, host string) bool {
 	if last, sent := w.lastSent[host]; !sent || now.Sub(last) >= target.Wait {
 		w.lastSent[host] = now
 		w.mu.Unlock()
-		if err := Send(target.MAC, target.Broadcast); err != nil {
+		if !sendAll(target.MAC, target.Broadcast, target.Broadcasts) {
 			return false
 		}
 		w.mu.Lock()