Services

JobServer

Landscape

JobServer 包含 Schedulers 及 Workers。Scheduler 中包含一组 Scheduler 实例，用于定时调度 Job。Workers 包含了固定种类的 Worker 实例，每个实例独自工作。JobServer 用于创建、查询、更改 Job 状态，并持久化到 Store 中。
Worker 的实现通过向 JobServer 注册 Worker Generator 来实现。具体的实现不在开源项目中。同时，Worker 与 Scheduler 成对出现，均由使用者自己实现，因此，细节不能继续讨论。

var accountMigrationInterface func(*Server) einterfaces.AccountMigrationInterface
func RegisterAccountMigrationInterface(f func(*Server) einterfaces.AccountMigrationInterface) {
    accountMigrationInterface = f
}

HTTPService

Landscape

Core

首先创建基础的 Dialer 结构，并配置参数。

dialContext := (&net.Dialer{
    Timeout:   ConnectTimeout,
    KeepAlive: 30 * time.Second,
}).DialContext

将基础的 DialContext 传入，进行增强后，返回新的 DialContext。

func dialContextFilter(dial DialContextFunction, allowHost func(host string) bool, allowIP func(ip net.IP) bool) DialContextFunction {
    return func(ctx context.Context, network, addr string) (net.Conn, error) {
        host, port, err := net.SplitHostPort(addr)
        if err != nil {
            return nil, err
        }
        if allowHost != nil && allowHost(host) {
            return dial(ctx, network, addr)
        }
        ips, err := net.LookupIP(host)
        if err != nil {
            return nil, err
        }
        var firstErr error
        for _, ip := range ips {
            select {
            case <-ctx.Done():
                return nil, ctx.Err()
            default:
            }
            if allowIP == nil || !allowIP(ip) {
                continue
            }
            conn, err := dial(ctx, network, net.JoinHostPort(ip.String(), port))
            if err == nil {
                return conn, nil
            }
            if firstErr == nil {
                firstErr = err
            }
        }
        if firstErr == nil {
            return nil, AddressForbidden
        }
        return nil, firstErr
    }
}

File Store

Landscape

FileBackend 接口如下

type FileBackend interface {
    TestConnection() *model.AppError
    Reader(path string) (ReadCloseSeeker, *model.AppError)
    ReadFile(path string) ([]byte, *model.AppError)
    FileExists(path string) (bool, *model.AppError)
    CopyFile(oldPath, newPath string) *model.AppError
    MoveFile(oldPath, newPath string) *model.AppError
    WriteFile(fr io.Reader, path string) (int64, *model.AppError)
    RemoveFile(path string) *model.AppError
    ListDirectory(path string) (*[]string, *model.AppError)
    RemoveDirectory(path string) *model.AppError
}

Image Proxy

References

• willnorris/imageproxy: A caching, resizing image proxy written in Go

Landscape

Details

LocalBackend 获取图片的处理，注意其中的 Headers。

func (backend *LocalBackend) GetImage(w http.ResponseWriter, r *http.Request, imageURL string) {
    // The interface to the proxy only exposes a ServeHTTP method, so fake a request to it
    req, err := http.NewRequest(http.MethodGet, "/"+imageURL, nil)
    if err != nil {
        // http.NewRequest should only return an error on an invalid URL
        mlog.Error("Failed to create request for proxied image", mlog.String("url", imageURL), mlog.Err(err))
        w.WriteHeader(http.StatusBadRequest)
        w.Write([]byte{})
        return
    }
    w.Header().Set("X-Frame-Options", "deny")
    w.Header().Set("X-XSS-Protection", "1; mode=block")
    w.Header().Set("X-Content-Type-Options", "nosniff")
    w.Header().Set("Content-Security-Policy", "default-src 'none'; img-src data:; style-src 'unsafe-inline'")
    backend.impl.ServeHTTP(w, req)
}