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243 lines
4.2 KiB
243 lines
4.2 KiB
package comments
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import (
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"bytes"
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"crypto/subtle"
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"encoding/json"
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"fmt"
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"io"
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"net/http"
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"sync"
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"time"
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"github.com/peterbourgon/diskv"
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)
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type Comment struct {
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Name, Text string
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IP string
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Date time.Time
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Spam bool
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}
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func MarshalJSON(c Comment) ([]byte, error) {
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buf := new(bytes.Buffer)
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err := json.NewEncoder(buf).Encode(c)
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return buf.Bytes(), err
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}
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func UnmarshalJSON(b []byte) (Comment, error) {
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var c Comment
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err := json.NewDecoder(bytes.NewBuffer(b)).Decode(&c)
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return c, err
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}
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func Default() *Service {
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return WithStorage(NewDiskv("comments"))
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}
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func WithStorage(storage Storage) *Service {
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return &Service{Storage: storage}
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}
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type Service struct {
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Storage Storage
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Password string
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}
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type Storage interface {
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Store(post string, c Comment) error
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Retreive(post string) ([]Comment, error)
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ReadAll(post string) (io.Reader, error)
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}
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func (cs *Service) User(r *http.Request) (string, bool) {
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if cs.Password == "" {
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return "", true
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}
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user, providedPass, ok := r.BasicAuth()
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if ok && subtle.ConstantTimeCompare([]byte(cs.Password), []byte(providedPass)) == 1 {
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return user, true
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}
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return "", false
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}
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func (cs *Service) ServeComments(post string, w http.ResponseWriter, r *http.Request) error {
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user, allowed := cs.User(r)
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if !allowed {
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w.WriteHeader(401)
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return nil
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}
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if r.Method == "POST" {
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return cs.Comment(post, Comment{
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Name: user,
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Text: r.FormValue("Text"),
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IP: r.RemoteAddr,
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Date: time.Now(),
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})
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}
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_, err := cs.WriteTo(post, w)
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if err != nil {
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return err
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}
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return nil
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}
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func (cs *Service) Comment(post string, c Comment) error {
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return cs.Storage.Store(post, c)
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}
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func (cs *Service) Load(post string) ([]Comment, error) {
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return cs.Storage.Retreive(post)
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}
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func (cs *Service) WriteTo(post string, w io.Writer) (int64, error) {
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r, err := cs.Storage.ReadAll(post)
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if err != nil {
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return 0, err
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}
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return io.Copy(w, r)
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}
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type diskvStorage struct {
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*diskv.Diskv
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keyMtx sync.Mutex
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keyLastKnown int64
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}
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func (d *diskvStorage) nextKey(post string) (string, error) {
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d.keyMtx.Lock()
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defer d.keyMtx.Unlock()
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var i uint64
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prefix := post + "-"
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keys := d.KeysPrefix(prefix, nil)
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for range keys {
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i++
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}
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key := prefix + fmt.Sprint(i)
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err := d.WriteStream(key, &bytes.Buffer{}, true)
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return key, err
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}
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func (d *diskvStorage) Store(post string, c Comment) error {
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b, err := MarshalJSON(c)
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if err != nil {
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return fmt.Errorf("error marshaling comment for storage: %v", err)
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}
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key, err := d.nextKey(post)
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if err != nil {
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return fmt.Errorf("error recording comment: %v", err)
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}
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err = d.Write(key, b)
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if err != nil {
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return fmt.Errorf("error writing comment to storage: %v", err)
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}
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return nil
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}
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type multiReadCloser struct {
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rcs []io.ReadCloser
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}
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func (mrc *multiReadCloser) Read(b []byte) (int, error) {
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if len(mrc.rcs) == 0 {
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return 0, io.EOF
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}
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n, err := mrc.rcs[0].Read(b)
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if n == len(b) { // we read enough
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return n, err
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}
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for (err == nil || err == io.EOF) && len(mrc.rcs) > 1 {
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var n2 int
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closeErr := mrc.rcs[0].Close()
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if closeErr != nil {
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return n, closeErr
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}
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mrc.rcs = mrc.rcs[1:]
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n2, err = mrc.rcs[0].Read(b[n:])
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n += n2
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}
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return n, err
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}
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func (mrc *multiReadCloser) Close() error {
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var err error
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for _, rc := range mrc.rcs {
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err2 := rc.Close()
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if err2 != nil {
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err = err2
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}
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}
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if err != nil {
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return err
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}
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return nil
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}
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func (d *diskvStorage) ReadAll(post string) (io.Reader, error) {
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prefix := post + "-"
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var rcs []io.ReadCloser
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keys := d.KeysPrefix(prefix, nil)
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for key := range keys {
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rc, err := d.ReadStream(key, false)
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if err != nil {
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return nil, err
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}
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rcs = append(rcs, rc)
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}
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return &multiReadCloser{rcs}, nil
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}
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func (d *diskvStorage) Retreive(post string) ([]Comment, error) {
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var comments []Comment
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r, err := d.ReadAll(post)
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if err != nil {
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return comments, fmt.Errorf("error reading comment from storage: %v", err)
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}
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dec := json.NewDecoder(r)
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for dec.More() {
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comment := Comment{}
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err := dec.Decode(&comment)
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if err != nil {
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return comments, fmt.Errorf("error unmarshaling comment: %v", err)
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}
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}
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return comments, nil
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}
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func NewDiskv(path string) Storage {
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return &diskvStorage{
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Diskv: diskv.New(diskv.Options{
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BasePath: path,
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CacheSizeMax: 1024 * 1024,
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}),
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}
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}
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