ntfy/server/util.go

package server

import (
	"encoding/json"
	"firebase.google.com/go/messaging"
	"net/http"
	"strings"
)

const (
	fcmMessageLimit = 4000
)

// maybeTruncateFCMMessage performs best-effort truncation of FCM messages.
// The docs say the limit is 4000 characters, but during testing it wasn't quite clear
// what fields matter; so we're just capping the serialized JSON to 4000 bytes.
func maybeTruncateFCMMessage(m *messaging.Message) *messaging.Message {
	s, err := json.Marshal(m)
	if err != nil {
		return m
	}
	if len(s) > fcmMessageLimit {
		over := len(s) - fcmMessageLimit + 16 // = len("truncated":"1",), sigh ...
		message, ok := m.Data["message"]
		if ok && len(message) > over {
			m.Data["truncated"] = "1"
			m.Data["message"] = message[:len(message)-over]
		}
	}
	return m
}

func readBoolParam(r *http.Request, defaultValue bool, names ...string) bool {
	value := strings.ToLower(readParam(r, names...))
	if value == "" {
		return defaultValue
	}
	return value == "1" || value == "yes" || value == "true"
}

func readParam(r *http.Request, names ...string) string {
	for _, name := range names {
		value := r.Header.Get(name)
		if value != "" {
			return strings.TrimSpace(value)
		}
	}
	for _, name := range names {
		value := r.URL.Query().Get(strings.ToLower(name))
		if value != "" {
			return strings.TrimSpace(value)
		}
	}
	return ""
}