Feat: aria2 download and transfer in slave node (#1040)

* Feat: retrieve nodes from data table

* Feat: master node ping slave node in REST API

* Feat: master send scheduled ping request

* Feat: inactive nodes recover loop

* Modify: remove database operations from aria2 RPC caller implementation

* Feat: init aria2 client in master node

* Feat: Round Robin load balancer

* Feat: create and monitor aria2 task in master node

* Feat: salve receive and handle heartbeat

* Fix: Node ID will be 0 in download record generated in older version

* Feat: sign request headers with all `X-` prefix

* Feat: API call to slave node will carry meta data in headers

* Feat: call slave aria2 rpc method from master

* Feat: get slave aria2 task status
Feat: encode slave response data using gob

* Feat: aria2 callback to master node / cancel or select task to slave node

* Fix: use dummy aria2 client when caller initialize failed in master node

* Feat: slave aria2 status event callback / salve RPC auth

* Feat: prototype for slave driven filesystem

* Feat: retry for init aria2 client in master node

* Feat: init request client with global options

* Feat: slave receive async task from master

* Fix: competition write in request header

* Refactor: dependency initialize order

* Feat: generic message queue implementation

* Feat: message queue implementation

* Feat: master waiting slave transfer result

* Feat: slave transfer file in stateless policy

* Feat: slave transfer file in slave policy

* Feat: slave transfer file in local policy

* Feat: slave transfer file in OneDrive policy

* Fix: failed to initialize update checker http client

* Feat: list slave nodes for dashboard

* Feat: test aria2 rpc connection in slave

* Feat: add and save node

* Feat: add and delete node in node pool

* Fix: temp file cannot be removed when aria2 task fails

* Fix: delete node in admin panel

* Feat: edit node and get node info

* Modify: delete unused settings

pkg/aria2/common/common.go

@@ -0,0 +1,114 @@
+package common
+
+import (
+	model "github.com/cloudreve/Cloudreve/v3/models"
+	"github.com/cloudreve/Cloudreve/v3/pkg/aria2/rpc"
+	"github.com/cloudreve/Cloudreve/v3/pkg/serializer"
+)
+
+// Aria2 离线下载处理接口
+type Aria2 interface {
+	// Init 初始化客户端连接
+	Init() error
+	// CreateTask 创建新的任务
+	CreateTask(task *model.Download, options map[string]interface{}) (string, error)
+	// 返回状态信息
+	Status(task *model.Download) (rpc.StatusInfo, error)
+	// 取消任务
+	Cancel(task *model.Download) error
+	// 选择要下载的文件
+	Select(task *model.Download, files []int) error
+	// 获取离线下载配置
+	GetConfig() model.Aria2Option
+	// 删除临时下载文件
+	DeleteTempFile(*model.Download) error
+}
+
+const (
+	// URLTask 从URL添加的任务
+	URLTask = iota
+	// TorrentTask 种子任务
+	TorrentTask
+)
+
+const (
+	// Ready 准备就绪
+	Ready = iota
+	// Downloading 下载中
+	Downloading
+	// Paused 暂停中
+	Paused
+	// Error 出错
+	Error
+	// Complete 完成
+	Complete
+	// Canceled 取消/停止
+	Canceled
+	// Unknown 未知状态
+	Unknown
+)
+
+var (
+	// ErrNotEnabled 功能未开启错误
+	ErrNotEnabled = serializer.NewError(serializer.CodeNoPermissionErr, "离线下载功能未开启", nil)
+	// ErrUserNotFound 未找到下载任务创建者
+	ErrUserNotFound = serializer.NewError(serializer.CodeNotFound, "无法找到任务创建者", nil)
+)
+
+// DummyAria2 未开启Aria2功能时使用的默认处理器
+type DummyAria2 struct {
+}
+
+func (instance *DummyAria2) Init() error {
+	return nil
+}
+
+// CreateTask 创建新任务，此处直接返回未开启错误
+func (instance *DummyAria2) CreateTask(model *model.Download, options map[string]interface{}) (string, error) {
+	return "", ErrNotEnabled
+}
+
+// Status 返回未开启错误
+func (instance *DummyAria2) Status(task *model.Download) (rpc.StatusInfo, error) {
+	return rpc.StatusInfo{}, ErrNotEnabled
+}
+
+// Cancel 返回未开启错误
+func (instance *DummyAria2) Cancel(task *model.Download) error {
+	return ErrNotEnabled
+}
+
+// Select 返回未开启错误
+func (instance *DummyAria2) Select(task *model.Download, files []int) error {
+	return ErrNotEnabled
+}
+
+// GetConfig 返回空的
+func (instance *DummyAria2) GetConfig() model.Aria2Option {
+	return model.Aria2Option{}
+}
+
+// GetConfig 返回空的
+func (instance *DummyAria2) DeleteTempFile(src *model.Download) error {
+	return ErrNotEnabled
+}
+
+// GetStatus 将给定的状态字符串转换为状态标识数字
+func GetStatus(status string) int {
+	switch status {
+	case "complete":
+		return Complete
+	case "active":
+		return Downloading
+	case "waiting":
+		return Ready
+	case "paused":
+		return Paused
+	case "error":
+		return Error
+	case "removed":
+		return Canceled
+	default:
+		return Unknown
+	}
+}