IoT/internal/service/api/handler/mqtt_auth.go

// mqtt_auth.go — HTTP-auth и ACL для EMQX (MQTT CONNECT / pub-sub).
//
// Endpoints (без JWT, вызываются EMQX внутри платформы):
//
//	POST /internal/mqtt/auth — аутентификация: всегда HTTP 200, {"result":"allow"|"deny"}
//	POST /internal/mqtt/acl  — авторизация pub/sub
//
// Источник устройств — таблица iot_devices (не k8s Secrets).
package handler

import (
	"crypto/subtle"
	"encoding/json"
	"errors"
	"net/http"
	"strings"

	"gitea.services.ngcloud.ru/Nail/IoT/internal/service/store"
)

// mqttAuthRequest — тело запроса от EMQX 5.x (username, password, clientid, peerhost).
type mqttAuthRequest struct {
	Username string `json:"username"`
	Password string `json:"password"`
	ClientID string `json:"clientid"`
	PeerHost string `json:"peerhost"`
}

// mqttAuthResponse — ответ для EMQX (всегда HTTP 200).
type mqttAuthResponse struct {
	Result string    `json:"result"`
	ACL    []aclRule `json:"acl,omitempty"`
}

// aclRule — правило ACL для EMQX HTTP auth.
type aclRule struct {
	Permission string `json:"permission"`
	Action     string `json:"action"`
	Topic      string `json:"topic"`
}

// mqttAclRequest — тело запроса ACL от EMQX.
type mqttAclRequest struct {
	Username string `json:"username"`
	ClientID string `json:"clientid"`
	Action   string `json:"action"`
	Topic    string `json:"topic"`
}

// MQTTAuth — POST /internal/mqtt/auth.
//
// Логика:
//  1. bridge-креды (MQTT_USERNAME/MQTT_PASSWORD из env) — проверяются до парсинга;
//  2. username "{ns}_{deviceId}" → поиск устройства в iot_devices;
//  3. constant-time сравнение пароля; проверка enabled;
//  4. best-effort last_connected; ACL по топику устройства.
func (h *Handler) MQTTAuth(w http.ResponseWriter, r *http.Request) {
	var req mqttAuthRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}

	// Внутренний bridge-клиент: фиксированные креды, ACL выдаётся ниже.
	if h.Cfg.MQTTUsername != "" && req.Username == h.Cfg.MQTTUsername {
		if subtle.ConstantTimeCompare([]byte(h.Cfg.MQTTPassword), []byte(req.Password)) == 1 {
			writeJSON(w, http.StatusOK, mqttAuthResponse{
				Result: "allow",
				ACL:    bridgeACLRules(),
			})
			return
		}
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}

	// Парсим username: "{namespace}_{deviceId}" (первый '_' — разделитель).
	idx := strings.Index(req.Username, "_")
	if idx <= 0 || idx == len(req.Username)-1 {
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}
	ns := req.Username[:idx]
	deviceID := req.Username[idx+1:]

	device, err := h.Devices.GetByDeviceID(r.Context(), ns, deviceID)
	if err != nil {
		if !errors.Is(err, store.ErrNotFound) {
			h.Log.Error("mqtt auth: device lookup", "namespace", ns, "device", deviceID, "err", err)
		}
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}
	if !device.Enabled {
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}
	if subtle.ConstantTimeCompare([]byte(device.MQTTPassword), []byte(req.Password)) != 1 {
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}

	// best-effort: обновляем время последнего подключения
	h.Devices.TouchLastConnected(r.Context(), ns, deviceID)

	writeJSON(w, http.StatusOK, mqttAuthResponse{
		Result: "allow",
		ACL:    deviceACLRules(ns, deviceID),
	})
}

// MQTTAcl — POST /internal/mqtt/acl.
//
// Bridge (clientID из env MQTT_CLIENT_ID): только subscribe.
// Устройство ({ns}_{deviceId}): pub/sub в своём топике.
func (h *Handler) MQTTAcl(w http.ResponseWriter, r *http.Request) {
	var req mqttAclRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}

	if req.ClientID == h.Cfg.MQTTClientID {
		if req.Action == "subscribe" {
			writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "allow"})
			return
		}
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}

	idx := strings.Index(req.Username, "_")
	if idx <= 0 || idx == len(req.Username)-1 {
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
		return
	}
	ns := req.Username[:idx]
	deviceID := req.Username[idx+1:]
	deviceTopic := ns + "/telemetry/" + deviceID

	switch {
	case req.Action == "publish" && req.Topic == deviceTopic:
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "allow"})
	case req.Action == "subscribe" && (req.Topic == deviceTopic || req.Topic == "#"):
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "allow"})
	default:
		writeJSON(w, http.StatusOK, mqttAuthResponse{Result: "deny"})
	}
}

// bridgeACLRules — ACL для внутреннего bridge: subscribe на все telemetry-топики.
func bridgeACLRules() []aclRule {
	return []aclRule{
		{Permission: "allow", Action: "subscribe", Topic: "+/telemetry/+"},
		{Permission: "deny", Action: "all", Topic: "#"},
	}
}

// deviceACLRules — ACL для устройства: только свой топик телеметрии.
func deviceACLRules(ns, deviceID string) []aclRule {
	topic := ns + "/telemetry/" + deviceID
	return []aclRule{
		{Permission: "allow", Action: "publish", Topic: topic},
		{Permission: "allow", Action: "subscribe", Topic: topic},
		{Permission: "deny", Action: "all", Topic: "#"},
	}
}