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Implement deleting of pastes

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This commit is contained in:
Daan Sprenkels 2019-09-21 13:11:38 +02:00
parent 173ae7665b
commit 1c926a4864
4 changed files with 240 additions and 161 deletions
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22
assets/templates/txt/pasteMeta.txt.tmpl
View File

@ -1,5 +1,17 @@
key: {{.Paste.Key}}
type: {{.Paste.Type}}
state: {{.Paste.State}}
created: {{.Paste.TimeCreated}}
owner: {{if .IsOwner}}yes{{else}}no{{end}}
METADATA on <{{.Request.Host}}/{{.Paste.Key}}>:
TYPE: {{.Paste.Type}}
STATE: {{.Paste.State}}
{{if .Paste.TimeCreated.IsZero -}}
CREATED: undefined
{{else -}}
CREATED: {{.Paste.TimeCreated}}
{{end -}}
DELETE TOKEN: {{.CanDelete.String}}
{{if and (ne .Paste.State.String "deleted") .CanDelete.Bool}}
```
# To delete this {{.Paste.Type}}, execute:
curl --request "DELETE" "{{.Request.Host}}/{{.Paste.Key}}?deleteToken={{.Request.URL.Query.Get "deleteToken"}}"
```
{{end}}

354
handlers/handlers.go
View File

@ -4,13 +4,13 @@ import (
"crypto/rand"
"crypto/subtle"
"encoding/base64"
"encoding/hex"
"fmt"
"log"
"net/http"
"net/url"
"strings"
"time"
"unicode"
"github.com/gorilla/mux"
"github.com/pkg/errors"
@ -20,29 +20,39 @@ import (
"gitea.hashru.nl/dsprenkels/rushlink/gobmarsh"
)
type PasteType int
type PasteState int
type pasteType int
type pasteState int
type StoredPaste struct {
Type PasteType
State PasteState
type storedPaste struct {
Type pasteType
State pasteState
Content []byte
Key string
OwnerToken [16]byte
DeleteToken [16]byte
TimeCreated time.Time
}
const (
TypePaste PasteType = iota
TypeRedirect
typeUndef pasteType = 0
typePaste = 1
typeRedirect = 2
)
const (
StatePresent PasteState = iota
StateDeleted
stateUndef pasteState = 0
statePresent = 1
stateDeleted = 2
)
const CookieOwnerToken = "owner_token"
type viewPaste uint
const (
_ viewPaste = 1 << iota
viewNoRedirect
viewShowMeta
)
const CookieDeleteToken = "owner_token"
// These keys are designated reserved, and will not be randomly chosen
var ReservedPasteKeys = []string{"xd42", "example"}
@ -51,22 +61,26 @@ var ReservedPasteKeys = []string{"xd42", "example"}
var base64Alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
var base64Encoder = base64.RawURLEncoding.WithPadding(base64.NoPadding)
func (t PasteType) String() string {
func (t pasteType) String() string {
switch t {
case TypePaste:
case typeUndef:
return "unknown"
case typePaste:
return "paste"
case TypeRedirect:
case typeRedirect:
return "redirect"
default:
return "invalid"
}
}
func (t PasteState) String() string {
func (t pasteState) String() string {
switch t {
case StatePresent:
case stateUndef:
return "unknown"
case statePresent:
return "present"
case StateDeleted:
case stateDeleted:
return "deleted"
default:
return "invalid"
@ -74,10 +88,89 @@ func (t PasteState) String() string {
}
func indexGetHandler(w http.ResponseWriter, r *http.Request) {
render(w, r, "index", nil)
render(w, r, "index", map[string]interface{}{})
}
func indexPostHandler(w http.ResponseWriter, r *http.Request) {
func viewPasteHandler(w http.ResponseWriter, r *http.Request) {
viewPasteHandlerInner(w, r, 0)
}
func viewPasteHandlerNoRedirect(w http.ResponseWriter, r *http.Request) {
viewPasteHandlerInner(w, r, viewNoRedirect)
}
func viewPasteHandlerMeta(w http.ResponseWriter, r *http.Request) {
viewPasteHandlerInner(w, r, viewShowMeta)
}
func viewPasteHandlerInner(w http.ResponseWriter, r *http.Request, flags viewPaste) {
vars := mux.Vars(r)
key := vars["key"]
var storedPaste *storedPaste
if err := db.DB.View(func(tx *bolt.Tx) error {
var err error
storedPaste, err = getURL(tx, key)
return err
}); err != nil {
log.Printf("error: %v\n", err)
renderInternalServerError(w, r, err)
return
}
if storedPaste == nil {
renderError(w, r, http.StatusNotFound, "url key not found in the database")
return
}
if flags&viewShowMeta != 0 {
canDelete := struct {
Bool bool
String string
}{Bool: false}
deleteToken, err := getDeleteTokenFromRequest(r)
if err != nil {
canDelete.String = "invalid"
} else if deleteToken == nil {
canDelete.String = "undefined"
} else {
if subtle.ConstantTimeCompare(deleteToken[:], storedPaste.DeleteToken[:]) == 1 {
canDelete.Bool = true
canDelete.String = "correct"
} else {
canDelete.String = "invalid"
}
}
data := map[string]interface{}{
"Paste": storedPaste,
"CanDelete": canDelete,
}
render(w, r, "pasteMeta", data)
return
}
switch storedPaste.State {
case statePresent:
if flags&viewNoRedirect == 0 {
rawurl := string(storedPaste.Content)
urlParse, err := url.Parse(rawurl)
if err != nil {
log.Printf("error: invalid URL ('%v') in database for key '%v': %v\n", rawurl, storedPaste.Key, err)
renderInternalServerError(w, r, "invalid url in database")
return
}
http.Redirect(w, r, urlParse.String(), http.StatusSeeOther)
}
w.Write(storedPaste.Content)
case stateDeleted:
renderError(w, r, http.StatusGone, "key has been deleted")
default:
log.Printf("error: invalid storedPaste.State (%v) for key '%v'\n", storedPaste.State, storedPaste.Key)
msg := fmt.Sprintf("internal server error: invalid storedPaste.State (%v\n)", storedPaste.State)
renderInternalServerError(w, r, msg)
}
}
func newPasteHandler(w http.ResponseWriter, r *http.Request) {
if err := r.ParseMultipartForm(50 * 1000 * 1000); err != nil {
log.Printf("error: %v\n", err)
renderInternalServerError(w, r, err)
@ -99,77 +192,10 @@ func indexPostHandler(w http.ResponseWriter, r *http.Request) {
return
}
shortenPostHandler(w, r)
newRedirectPasteHandler(w, r)
}
func pasteGetHandler(w http.ResponseWriter, r *http.Request) {
pasteGetHandlerInner(w, r, false, false)
}
func pasteGetHandlerNoRedirect(w http.ResponseWriter, r *http.Request) {
pasteGetHandlerInner(w, r, true, false)
}
func pasteGetHandlerMeta(w http.ResponseWriter, r *http.Request) {
pasteGetHandlerInner(w, r, false, true)
}
func pasteGetHandlerInner(w http.ResponseWriter, r *http.Request, noRedirect, showMeta bool) {
vars := mux.Vars(r)
key := vars["key"]
var storedPaste *StoredPaste
if err := db.DB.View(func(tx *bolt.Tx) error {
var err error
storedPaste, err = getURL(tx, []byte(key))
return err
}); err != nil {
log.Printf("error: %v\n", err)
renderInternalServerError(w, r, err)
return
}
if storedPaste == nil {
renderError(w, r, http.StatusNotFound, "url key not found in the database")
return
}
if showMeta {
isOwner := false
ownerToken, ok := getOwnerTokenFromRequest(r)
if ok && subtle.ConstantTimeCompare(ownerToken[:], storedPaste.OwnerToken[:]) == 1 {
isOwner = true
}
data := map[string]interface{}{
"Paste": storedPaste,
"IsOwner": isOwner,
}
render(w, r, "pasteMeta", data)
return
}
switch storedPaste.State {
case StatePresent:
if !noRedirect {
rawurl := string(storedPaste.Content)
urlParse, err := url.Parse(rawurl)
if err != nil {
log.Printf("error: invalid URL ('%v') in database for key '%v': %v\n", rawurl, storedPaste.Key, err)
renderInternalServerError(w, r, "invalid url in database")
return
}
http.Redirect(w, r, urlParse.String(), http.StatusSeeOther)
}
w.Write(storedPaste.Content)
case StateDeleted:
renderError(w, r, http.StatusGone, "key has been deleted")
default:
log.Printf("error: invalid storedPaste.State (%v) for key '%v'\n", storedPaste.State, storedPaste.Key)
msg := fmt.Sprintf("internal server error: invalid storedPaste.State (%v\n)", storedPaste.State)
renderInternalServerError(w, r, msg)
}
}
func shortenPostHandler(w http.ResponseWriter, r *http.Request) {
func newRedirectPasteHandler(w http.ResponseWriter, r *http.Request) {
rawurl := r.PostForm.Get("shorten")
userURL, err := url.ParseRequestURI(rawurl)
if err != nil {
@ -186,18 +212,15 @@ func shortenPostHandler(w http.ResponseWriter, r *http.Request) {
return
}
var storedPaste *StoredPaste
var storedPaste *storedPaste
if err := db.DB.Update(func(tx *bolt.Tx) error {
ownerKey, ok := getOwnerTokenFromRequest(r)
if ok == false {
// Owner key not supplied or invalid, generate a new one
ownerKey, err = generateOwnerToken()
if err != nil {
return errors.Wrap(err, "generating OwnerToken")
}
// Generate a new delete token for this paste
deleteToken, err := generateDeleteToken()
if err != nil {
return errors.Wrap(err, "generating delete token")
}
sp, err := shortenURL(tx, userURL, ownerKey)
sp, err := shortenURL(tx, userURL, deleteToken)
storedPaste = sp
return err
}); err != nil {
@ -206,34 +229,71 @@ func shortenPostHandler(w http.ResponseWriter, r *http.Request) {
return
}
saveURL, err := r.URL.Parse(string(storedPaste.Key))
deleteToken := hex.EncodeToString(storedPaste.DeleteToken[:])
saveRawurl := fmt.Sprintf("%v/%v?deleteToken=%v", r.Host, string(storedPaste.Key), deleteToken)
saveURL, err := r.URL.Parse(saveRawurl)
if err != nil {
err = errors.Wrap(err, "parsing url")
log.Printf("error: %v\n", err)
renderInternalServerError(w, r, err)
return
}
var base64OwnerToken = make([]byte, 24)
base64Encoder.Encode(base64OwnerToken, storedPaste.OwnerToken[:])
// TODO(dsprenkels) Put this into a template
w.WriteHeader(http.StatusOK)
fmt.Fprintf(w, "URL saved at %v\n", saveURL)
isNotPrint := func(r rune) bool { return !unicode.IsPrint(r) }
fmt.Fprintf(w, "Owner key is %s\n", strings.TrimRightFunc(string(base64OwnerToken), isNotPrint))
fmt.Fprintf(w, "%v\n", saveURL)
}
// Delete a URL from the database
func deletePasteHandler(w http.ResponseWriter, r *http.Request) {
// TODO(dsprenkels) LEFT HERE; this functionality still untested
vars := mux.Vars(r)
key := vars["key"]
deleteToken, err := getDeleteTokenFromRequest(r)
if err != nil {
renderError(w, r, http.StatusBadRequest, "invalid delete token")
return
} else if deleteToken == nil {
renderError(w, r, http.StatusBadRequest, "no delete token provided")
return
}
var errorCode int
if err := db.DB.Update(func(tx *bolt.Tx) error {
paste, err := getURL(tx, key)
if err != nil {
errorCode = http.StatusNotFound
return err
}
if subtle.ConstantTimeCompare(deleteToken[:], paste.DeleteToken[:]) == 1 {
// Replace the old paste with a new empty paste
return savePaste(tx, key, storedPaste{
Key: paste.Key,
State: stateDeleted,
DeleteToken: paste.DeleteToken,
})
}
errorCode = http.StatusForbidden
return errors.New("invalid delete token")
}); err != nil {
log.Printf("error: %v\n", err)
renderError(w, r, errorCode, fmt.Sprintf("error: %v", err))
return
}
}
// Retrieve a URL from the database
func getURL(tx *bolt.Tx, key []byte) (*StoredPaste, error) {
shortenBucket := tx.Bucket([]byte(db.BUCKET_PASTES))
if shortenBucket == nil {
return nil, fmt.Errorf("bucket %v does not exist", db.BUCKET_PASTES)
func getURL(tx *bolt.Tx, key string) (*storedPaste, error) {
pastesBucket := tx.Bucket([]byte(db.BUCKET_PASTES))
if pastesBucket == nil {
return nil, errors.Errorf("bucket %v does not exist", db.BUCKET_PASTES)
}
storedBytes := shortenBucket.Get(key)
storedBytes := pastesBucket.Get([]byte(key))
if storedBytes == nil {
return nil, nil
}
storedPaste := &StoredPaste{}
storedPaste := &storedPaste{}
err := gobmarsh.Unmarshal(storedBytes, storedPaste)
return storedPaste, err
}
@ -241,10 +301,10 @@ func getURL(tx *bolt.Tx, key []byte) (*StoredPaste, error) {
// Add a new URL to the database
//
// Returns the new ID if the url was successfully shortened
func shortenURL(tx *bolt.Tx, userURL *url.URL, ownerKey [16]byte) (*StoredPaste, error) {
shortenBucket := tx.Bucket([]byte(db.BUCKET_PASTES))
if shortenBucket == nil {
return nil, fmt.Errorf("bucket %v does not exist", db.BUCKET_PASTES)
func shortenURL(tx *bolt.Tx, userURL *url.URL, deleteToken [16]byte) (*storedPaste, error) {
pastesBucket := tx.Bucket([]byte(db.BUCKET_PASTES))
if pastesBucket == nil {
return nil, errors.Errorf("bucket %v does not exist", db.BUCKET_PASTES)
}
// Generate a key until it is not in the database, this occurs in O(log N),
@ -258,7 +318,7 @@ func shortenURL(tx *bolt.Tx, userURL *url.URL, ownerKey [16]byte) (*StoredPaste,
return nil, errors.Wrap(err, "url-key generation failed")
}
found := shortenBucket.Get([]byte(urlKey))
found := pastesBucket.Get([]byte(urlKey))
if found == nil {
break
}
@ -278,24 +338,36 @@ func shortenURL(tx *bolt.Tx, userURL *url.URL, ownerKey [16]byte) (*StoredPaste,
}
// Store the new key
storedPaste := StoredPaste{
Type: TypeRedirect,
State: StatePresent,
storedPaste := storedPaste{
Type: typeRedirect,
State: statePresent,
Content: []byte(userURL.String()),
Key: urlKey,
OwnerToken: ownerKey,
DeleteToken: deleteToken,
TimeCreated: time.Now().UTC(),
}
storedBytes, err := gobmarsh.Marshal(storedPaste)
if err != nil {
return nil, errors.Wrap(err, "encoding for database failed")
}
if err := shortenBucket.Put([]byte(urlKey), storedBytes); err != nil {
return nil, errors.Wrap(err, "database transaction failed")
if err := savePaste(tx, urlKey, storedPaste); err != nil {
return nil, err
}
return &storedPaste, nil
}
func savePaste(tx *bolt.Tx, key string, paste storedPaste) error {
bucket := tx.Bucket([]byte(db.BUCKET_PASTES))
if bucket == nil {
return errors.Errorf("bucket %v does not exist", db.BUCKET_PASTES)
}
buf, err := gobmarsh.Marshal(paste)
if err != nil {
return errors.Wrap(err, "encoding for database failed")
}
if err := bucket.Put([]byte(key), buf); err != nil {
return errors.Wrap(err, "database transaction failed")
}
return nil
}
func generateURLKey(epoch int) (string, error) {
urlKey := make([]byte, 4+epoch)
_, err := rand.Read(urlKey)
@ -331,26 +403,26 @@ func generateURLKey(epoch int) (string, error) {
return string(urlKey), nil
}
func generateOwnerToken() ([16]byte, error) {
var ownerKey [16]byte
_, err := rand.Read(ownerKey[:])
func generateDeleteToken() ([16]byte, error) {
var deleteToken [16]byte
_, err := rand.Read(deleteToken[:])
if err != nil {
return ownerKey, err
return deleteToken, err
}
return ownerKey, nil
return deleteToken, nil
}
func getOwnerTokenFromRequest(r *http.Request) ([16]byte, bool) {
var ownerKey [16]byte
ownerKeyCookie, err := r.Cookie(CookieOwnerToken)
if err != nil && err != http.ErrNoCookie {
return ownerKey, false
func getDeleteTokenFromRequest(r *http.Request) (*[16]byte, error) {
deleteTokenQuery := r.URL.Query().Get("deleteToken")
if deleteTokenQuery == "" {
return nil, nil
}
if ownerKeyCookie != nil {
n, err := base64Encoder.Strict().Decode(ownerKey[:], []byte(ownerKeyCookie.Value))
if err == nil || n == 16 {
return ownerKey, true
}
var deleteToken [16]byte
n, err := hex.Decode(deleteToken[:], []byte(deleteTokenQuery))
if err != nil {
return nil, errors.Wrap(err, "decoding hex")
} else if n != 16 {
return nil, errors.Errorf("invalid deleteToken length (%v bytes)", n)
}
return ownerKey, false
return &deleteToken, nil
}

10
handlers/router.go
View File

@ -12,10 +12,12 @@ func StartMainServer() {
// Initialize Gorilla router
router := mux.NewRouter()
router.HandleFunc("/", indexGetHandler).Methods("GET")
router.HandleFunc("/", indexPostHandler).Methods("POST")
router.HandleFunc("/{key:[A-Za-z0-9-_]{4,}}", pasteGetHandler).Methods("GET")
router.HandleFunc("/{key:[A-Za-z0-9-_]{4,}}/nr", pasteGetHandlerNoRedirect).Methods("GET")
router.HandleFunc("/{key:[A-Za-z0-9-_]{4,}}/meta", pasteGetHandlerMeta).Methods("GET")
router.HandleFunc("/", newPasteHandler).Methods("POST")
router.HandleFunc("/{key:[A-Za-z0-9-_]{4,}}", viewPasteHandler).Methods("GET")
router.HandleFunc("/{key:[A-Za-z0-9-_]{4,}}/nr", viewPasteHandlerNoRedirect).Methods("GET")
router.HandleFunc("/{key:[A-Za-z0-9-_]{4,}}/meta", viewPasteHandlerMeta).Methods("GET")
router.HandleFunc("/{key:[A-Za-z0-9-_]{4,}}", deletePasteHandler).Methods("DELETE")
router.HandleFunc("/{key:[A-Za-z0-9-_]{4,}}/delete", deletePasteHandler).Methods("POST")
srv := &http.Server{
Handler: router,

15
handlers/views.go
View File

@ -79,6 +79,9 @@ func render(w http.ResponseWriter, r *http.Request, tmplName string, data map[st
fmt.Fprintf(w, "error parsing Accept header: %v\n", err)
}
// Add the request to the template data
data["Request"] = r
switch contentType {
case "text/plain":
w.Header().Set("Content-Type", "text/plain")
@ -97,7 +100,7 @@ func render(w http.ResponseWriter, r *http.Request, tmplName string, data map[st
}
// Construct a (lazy) plain-text view for inclusion in <pre>
pre := func() string {
data["Pre"] = func() string {
tmpl := textTemplates[tmplName]
if tmpl == nil {
panic(fmt.Errorf("'%v' not in textTemplates", tmplName))
@ -108,7 +111,6 @@ func render(w http.ResponseWriter, r *http.Request, tmplName string, data map[st
}
return buf.String()
}
data = mergeData(map[string]interface{}{"Pre": pre}, data)
err = tmpl.Execute(w, data)
default:
// Fall back to plain text without template
@ -131,15 +133,6 @@ func renderInternalServerError(w http.ResponseWriter, r *http.Request, err inter
renderError(w, r, http.StatusInternalServerError, msg)
}
// Merge the second data map into the first one, overwriting any key that is
// already present.
func mergeData(into, from map[string]interface{}) map[string]interface{} {
for k, v := range from {
into[k] = v
}
return into
}
// Try to resolve the preferred content-type for the response to this request.
//
// This is done by reading from the `types` argument. If one of them matches