electricdusk/rushlink
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refactor: Put paste model in separate file

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This commit is contained in:
Daan Sprenkels 2019-09-22 14:03:27 +02:00
parent f36ed4a4c7
commit 0ecdaafe2f
4 changed files with 190 additions and 163 deletions
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3
assets/templates/html/index.html.tmpl
View File

@ -8,6 +8,9 @@ the command line.
## USAGE
# Upload a file
curl -F'file=@yourfile.png' <a href="{{Request.Host}}">{{Request.Host}}</a>
# Shorten a URL
curl -F'shorten=http://example.com/some/long/url' <a href="{{Request.Host}}">{{Request.Host}}</a>

3
assets/templates/txt/index.txt.tmpl
View File

@ -6,6 +6,9 @@ the command line.
## USAGE
# Upload a file
curl -F'file=@yourfile.png' {{Request.Host}}
# Shorten a URL
curl -F'shorten=http://example.com/some/long/url' {{Request.Host}}

188
handlers/handlers.go
View File

@ -1,15 +1,12 @@
package handlers
import (
"crypto/rand"
"crypto/subtle"
"encoding/base64"
"encoding/hex"
"fmt"
"log"
"net/http"
"net/url"
"strings"
"time"
"github.com/gorilla/mux"
@ -17,31 +14,6 @@ import (
bolt "go.etcd.io/bbolt"
"gitea.hashru.nl/dsprenkels/rushlink/db"
"gitea.hashru.nl/dsprenkels/rushlink/gobmarsh"
)
type pasteType int
type pasteState int
type storedPaste struct {
Type pasteType
State pasteState
Content []byte
Key string
DeleteToken string
TimeCreated time.Time
}
const (
typeUndef pasteType = 0
typePaste = 1
typeRedirect = 2
)
const (
stateUndef pasteState = 0
statePresent = 1
stateDeleted = 2
)
type viewPaste uint
@ -106,17 +78,17 @@ func viewPasteHandlerMeta(w http.ResponseWriter, r *http.Request) {
func viewPasteHandlerInner(w http.ResponseWriter, r *http.Request, flags viewPaste) {
vars := mux.Vars(r)
key := vars["key"]
var storedPaste *storedPaste
var p *paste
if err := db.DB.View(func(tx *bolt.Tx) error {
var err error
storedPaste, err = getURL(tx, key)
p, err = getPaste(tx, key)
return err
}); err != nil {
log.Printf("error: %v\n", err)
renderInternalServerError(w, r, err)
return
}
if storedPaste == nil {
if p == nil {
renderError(w, r, http.StatusNotFound, "url key not found in the database")
return
}
@ -130,7 +102,7 @@ func viewPasteHandlerInner(w http.ResponseWriter, r *http.Request, flags viewPas
if deleteToken == "" {
canDelete.String = "undefined"
} else {
if subtle.ConstantTimeCompare([]byte(deleteToken), []byte(storedPaste.DeleteToken)) == 1 {
if subtle.ConstantTimeCompare([]byte(deleteToken), []byte(p.DeleteToken)) == 1 {
canDelete.Bool = true
canDelete.String = "correct"
} else {
@ -139,31 +111,31 @@ func viewPasteHandlerInner(w http.ResponseWriter, r *http.Request, flags viewPas
}
data := map[string]interface{}{
"Paste": storedPaste,
"Paste": p,
"CanDelete": canDelete,
}
render(w, r, "pasteMeta", data)
return
}
switch storedPaste.State {
switch p.State {
case statePresent:
if flags&viewNoRedirect == 0 {
rawurl := string(storedPaste.Content)
rawurl := string(p.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)
log.Printf("error: invalid URL ('%v') in database for key '%v': %v\n", rawurl, p.Key, err)
renderInternalServerError(w, r, "invalid url in database")
return
}
http.Redirect(w, r, urlParse.String(), http.StatusSeeOther)
}
w.Write(storedPaste.Content)
w.Write(p.Content)
case stateDeleted:
renderError(w, r, http.StatusGone, "paste 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)
log.Printf("error: invalid paste.State (%v) for key '%v'\n", p.State, p.Key)
msg := fmt.Sprintf("internal server error: invalid paste.State (%v\n)", p.State)
renderInternalServerError(w, r, msg)
}
}
@ -210,18 +182,18 @@ func newRedirectPasteHandler(w http.ResponseWriter, r *http.Request) {
return
}
var storedPaste *storedPaste
var paste *paste
if err := db.DB.Update(func(tx *bolt.Tx) error {
// Generate a new delete token for this paste
var err error
storedPaste, err = shortenURL(tx, userURL)
paste, err = shortenURL(tx, userURL)
return err
}); err != nil {
log.Printf("error: %v\n", err)
renderInternalServerError(w, r, err)
return
}
data := map[string]interface{}{"Paste": storedPaste}
data := map[string]interface{}{"Paste": paste}
render(w, r, "newRedirectPasteSuccess", data)
}
@ -238,18 +210,13 @@ func deletePasteHandler(w http.ResponseWriter, r *http.Request) {
var errorCode int
if err := db.DB.Update(func(tx *bolt.Tx) error {
paste, err := getURL(tx, key)
p, err := getPaste(tx, key)
if err != nil {
errorCode = http.StatusNotFound
return err
}
if subtle.ConstantTimeCompare([]byte(deleteToken), []byte(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,
})
if subtle.ConstantTimeCompare([]byte(deleteToken), []byte(p.DeleteToken)) == 1 {
p.delete(tx)
}
errorCode = http.StatusForbidden
return errors.New("invalid delete token")
@ -260,58 +227,13 @@ func deletePasteHandler(w http.ResponseWriter, r *http.Request) {
}
}
// Retrieve a URL from the database
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 := pastesBucket.Get([]byte(key))
if storedBytes == nil {
return nil, nil
}
storedPaste := &storedPaste{}
err := gobmarsh.Unmarshal(storedBytes, storedPaste)
return storedPaste, err
}
// 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) (*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),
// where N is the amount of keys stored in the url-shorten database.
epoch := 0
var urlKey string
for {
var err error
urlKey, err = generateURLKey(epoch)
if err != nil {
return nil, errors.Wrap(err, "url-key generation failed")
}
found := pastesBucket.Get([]byte(urlKey))
if found == nil {
break
}
isReserved := false
for _, reservedKey := range ReservedPasteKeys {
if strings.HasPrefix(urlKey, reservedKey) {
isReserved = true
break
}
}
if !isReserved {
break
}
epoch++
func shortenURL(tx *bolt.Tx, userURL *url.URL) (*paste, error) {
pasteKey, err := generatePasteKey(tx)
if err != nil {
return nil, errors.Wrap(err, "generating paste key")
}
// Also generate a deleteToken
@ -321,78 +243,18 @@ func shortenURL(tx *bolt.Tx, userURL *url.URL) (*storedPaste, error) {
}
// Store the new key
storedPaste := storedPaste{
p := paste{
Type: typeRedirect,
State: statePresent,
Content: []byte(userURL.String()),
Key: urlKey,
Key: pasteKey,
DeleteToken: deleteToken,
TimeCreated: time.Now().UTC(),
}
if err := savePaste(tx, urlKey, storedPaste); err != nil {
if err := p.save(tx); 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)
if err != nil {
return "", err
}
// Put all the values in the range 0..64 for easier base64-encoding
for i := 0; i < len(urlKey); i++ {
urlKey[i] &= 0x3F
}
// Implement truncate-resistance by forcing the prefix to
// 0b111110xxxxxxxxxx
// ^----- {epoch} ones followed by a single 0
//
// Example when epoch is 1: prefix is 0b10.
i := 0
for i < epoch {
// Set this bit to 1
limb := i / 6
bit := i % 6
urlKey[limb] |= 1 << uint(5-bit)
i++
}
// Finally set the next bit to 0
limb := i / 6
bit := i % 6
urlKey[limb] &= ^(1 << uint(5-bit))
// Convert this ID to a canonical base64 notation
for i := range urlKey {
urlKey[i] = base64Alphabet[urlKey[i]]
}
return string(urlKey), nil
}
func generateDeleteToken() (string, error) {
var deleteToken [16]byte
_, err := rand.Read(deleteToken[:])
if err != nil {
return "", err
}
return hex.EncodeToString(deleteToken[:]), nil
return &p, nil
}
func getDeleteTokenFromRequest(r *http.Request) string {

159
handlers/paste.go Normal file
View File

@ -0,0 +1,159 @@
package handlers
import (
"crypto/rand"
"encoding/hex"
"strings"
"time"
"gitea.hashru.nl/dsprenkels/rushlink/db"
"gitea.hashru.nl/dsprenkels/rushlink/gobmarsh"
"github.com/pkg/errors"
bolt "go.etcd.io/bbolt"
)
type pasteType int
type pasteState int
type paste struct {
Type pasteType
State pasteState
Content []byte
Key string
DeleteToken string
TimeCreated time.Time
}
const (
typeUndef pasteType = 0
typePaste = 1
typeRedirect = 2
)
const (
stateUndef pasteState = 0
statePresent = 1
stateDeleted = 2
)
// Retrieve a paste from the database
func getPaste(tx *bolt.Tx, key string) (*paste, error) {
pastesBucket := tx.Bucket([]byte(db.BUCKET_PASTES))
if pastesBucket == nil {
return nil, errors.Errorf("bucket %v does not exist", db.BUCKET_PASTES)
}
storedBytes := pastesBucket.Get([]byte(key))
if storedBytes == nil {
return nil, nil
}
p := &paste{}
err := gobmarsh.Unmarshal(storedBytes, p)
return p, err
}
func (p *paste) save(tx *bolt.Tx) 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(p)
if err != nil {
return errors.Wrap(err, "encoding for database failed")
}
if err := bucket.Put([]byte(p.Key), buf); err != nil {
return errors.Wrap(err, "database transaction failed")
}
return nil
}
func (p paste) delete(tx *bolt.Tx) error {
// Replace the old paste with a new empty paste
return (&paste{
Key: p.Key,
State: stateDeleted,
DeleteToken: p.DeleteToken,
}).save(tx)
}
// Generate a key until it is not in the database, this occurs in O(log N),
// where N is the amount of keys stored in the url-shorten database.
func generatePasteKey(tx *bolt.Tx) (string, error) {
pastesBucket := tx.Bucket([]byte(db.BUCKET_PASTES))
if pastesBucket == nil {
return "", errors.Errorf("bucket %v does not exist", db.BUCKET_PASTES)
}
epoch := 0
var key string
for {
var err error
key, err = generatePasteKeyInner(epoch)
if err != nil {
return "", errors.Wrap(err, "url-key generation failed")
}
found := pastesBucket.Get([]byte(key))
if found == nil {
break
}
isReserved := false
for _, reservedKey := range ReservedPasteKeys {
if strings.HasPrefix(key, reservedKey) {
isReserved = true
break
}
}
if !isReserved {
break
}
epoch++
}
return key, nil
}
func generatePasteKeyInner(epoch int) (string, error) {
urlKey := make([]byte, 4+epoch)
_, err := rand.Read(urlKey)
if err != nil {
return "", err
}
// Put all the values in the range 0..64 for easier base64-encoding
for i := 0; i < len(urlKey); i++ {
urlKey[i] &= 0x3F
}
// Implement truncate-resistance by forcing the prefix to
// 0b111110xxxxxxxxxx
// ^----- {epoch} ones followed by a single 0
//
// Example when epoch is 1: prefix is 0b10.
i := 0
for i < epoch {
// Set this bit to 1
limb := i / 6
bit := i % 6
urlKey[limb] |= 1 << uint(5-bit)
i++
}
// Finally set the next bit to 0
limb := i / 6
bit := i % 6
urlKey[limb] &= ^(1 << uint(5-bit))
// Convert this ID to a canonical base64 notation
for i := range urlKey {
urlKey[i] = base64Alphabet[urlKey[i]]
}
return string(urlKey), nil
}
func generateDeleteToken() (string, error) {
var deleteToken [16]byte
_, err := rand.Read(deleteToken[:])
if err != nil {
return "", err
}
return hex.EncodeToString(deleteToken[:]), nil
}