WIP: Clsuter support (cross node delivery, leader election)

cluster/util.go

@@ -0,0 +1,69 @@
+package cluster
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/netip"
+	"strings"
+
+	"heckel.io/ntfy/v2/log"
+	"heckel.io/ntfy/v2/model"
+)
+
+// messageURL derives the peer's message endpoint URL from its advertise URL.
+func messageURL(advertiseURL string) string {
+	return strings.TrimRight(advertiseURL, "/") + MessagePath
+}
+
+// stateURL derives the peer's state endpoint URL from its advertise URL.
+func stateURL(advertiseURL string) string {
+	return strings.TrimRight(advertiseURL, "/") + StatePath
+}
+
+// marshalMessage serializes one message and its non-JSON fields (Sender, User) as an
+// apiMessage line. Lines are marshaled once per publish and shared across all per-peer
+// queues; assembleMessageBody joins them without re-marshaling.
+func marshalMessage(m *model.Message) ([]byte, error) {
+	apiMsg := &apiMessage{User: m.User, Message: m}
+	if m.Sender.IsValid() {
+		apiMsg.Sender = m.Sender.String()
+	}
+	return json.Marshal(apiMsg)
+}
+
+// assembleMessageBody builds an NDJSON fan-out request body from pre-marshaled apiMessage
+// lines, avoiding a second JSON marshal of the messages.
+func assembleMessageBody(frags [][]byte) []byte {
+	return append(bytes.Join(frags, []byte("\n")), '\n')
+}
+
+// decodeMessageBody reads NDJSON apiMessage lines from r, reattaches the non-JSON fields
+// (Sender, User) onto each message, and hands them to deliver. Malformed or message-less lines
+// are skipped and logged, not fatal: fan-out is fire-and-forget, so the valid remainder of a
+// request is still delivered. It returns an error only for stream-level failures (e.g. a line
+// exceeding maxLineBytes).
+func decodeMessageBody(r io.Reader, maxLineBytes int, deliver DeliverFunc) error {
+	scanner := bufio.NewScanner(r)
+	scanner.Buffer(make([]byte, 64*1024), maxLineBytes)
+	for scanner.Scan() {
+		line := bytes.TrimSpace(scanner.Bytes())
+		if len(line) == 0 {
+			continue
+		}
+		var apiMsg apiMessage
+		if err := json.Unmarshal(line, &apiMsg); err != nil || apiMsg.Message == nil {
+			log.Tag(tag).Warn("Skipping malformed fan-out line")
+			continue
+		}
+		apiMsg.Message.User = apiMsg.User
+		if apiMsg.Sender != "" {
+			if addr, err := netip.ParseAddr(apiMsg.Sender); err == nil {
+				apiMsg.Message.Sender = addr
+			}
+		}
+		deliver(apiMsg.Message)
+	}
+	return scanner.Err()
+}