feat(hashing): add hash to generated links

README.md

@@ -97,6 +97,7 @@ In addition to the mandatory variables, you can also set the following optional
 
 - `HOST` :  A Fully Qualified Domain Name if present or use your server IP. (eg. `https://example.com` or `http://14.1.154.2:8080`)
 
+- `HASH_LENGTH` : This is the custom hash length for generated URLs. The hash length must be greater than 5 and less than or equal to 32. The default value is 6.
 
 ## Contributing
 

commands/stream.go

@@ -26,10 +26,11 @@ func sendLink(ctx *ext.Context, u *ext.Update) error {
 	if u.EffectiveMessage.Media == nil {
 		return dispatcher.EndGroups
 	}
-	if len(u.Entities.Chats) != 0 {
+	chatId := u.EffectiveChat().GetID()
+	peerChatId := storage.GetPeerById(chatId)
+	if peerChatId.Type != int(storage.TypeUser) {
 		return dispatcher.EndGroups
 	}
-	chatId := u.EffectiveChat().GetID()
 	peer := storage.GetPeerById(config.ValueOf.LogChannelID)
 	switch storage.EntityType(peer.Type) {
 	case storage.TypeChat:
@@ -57,7 +58,21 @@ func sendLink(ctx *ext.Context, u *ext.Update) error {
 		ctx.Reply(u, fmt.Sprintf("Error - %s", err.Error()), nil)
 		return dispatcher.EndGroups
 	}
-	link := fmt.Sprintf("%s/stream/%d", config.ValueOf.Host, messageID)
+	doc := update.(*tg.Updates).Updates[1].(*tg.UpdateNewChannelMessage).Message.(*tg.Message).Media
+	file, err := utils.FileFromMedia(doc)
+	if err != nil {
+		ctx.Reply(u, fmt.Sprintf("Error - %s", err.Error()), nil)
+		return dispatcher.EndGroups
+	}
+	fullHash := utils.PackFile(
+		file.FileName,
+		file.FileSize,
+		file.MimeType,
+		file.ID,
+	)
+
+	hash := utils.GetShortHash(fullHash)
+	link := fmt.Sprintf("%s/stream/%d?hash=%s", config.ValueOf.Host, messageID, hash)
 	ctx.Reply(u, link, nil)
 	return dispatcher.EndGroups
 }

config/config.go

@@ -19,6 +19,7 @@ type config struct {
 	Dev          bool   `envconfig:"DEV" default:"false"`
 	Port         int    `envconfig:"PORT" default:"8080"`
 	Host         string `envconfig:"HOST" default:"http://localhost:8080"`
+	HashLength   int    `envconfig:"HASH_LENGTH" default:"6"`
 }
 
 func (c *config) setupEnvVars() {
@@ -33,6 +34,18 @@ func Load(log *zap.Logger) {
 	defer log.Info("Loaded config")
 	ValueOf.setupEnvVars()
 	ValueOf.LogChannelID = int64(stripInt(log, int(ValueOf.LogChannelID)))
+	if ValueOf.HashLength == 0 {
+		log.Sugar().Info("HASH_LENGTH can't be 0, defaulting to 6")
+		ValueOf.HashLength = 6
+	}
+	if ValueOf.HashLength > 32 {
+		log.Sugar().Info("HASH_LENGTH can't be more than 32, changing to 32")
+		ValueOf.HashLength = 32
+	}
+	if ValueOf.HashLength < 5 {
+		log.Sugar().Info("HASH_LENGTH can't be less than 5, defaulting to 6")
+		ValueOf.HashLength = 6
+	}
 }
 
 func stripInt(log *zap.Logger, a int) int {

routes/stream.go

@@ -33,6 +33,12 @@ func getStreamRoute(ctx *gin.Context) {
 		return
 	}
 
+	authHash := ctx.Query("hash")
+	if authHash == "" {
+		http.Error(w, "missing hash param", http.StatusBadRequest)
+		return
+	}
+
 	ctx.Header("Accept-Ranges", "bytes")
 	var start, end int64
 	rangeHeader := r.Header.Get("Range")
@@ -48,6 +54,17 @@ func getStreamRoute(ctx *gin.Context) {
 		return
 	}
 
+	expectedHash := utils.PackFile(
+		file.FileName,
+		file.FileSize,
+		file.MimeType,
+		file.ID,
+	)
+	if !utils.CheckHash(authHash, expectedHash) {
+		http.Error(w, "invalid hash", http.StatusBadRequest)
+		return
+	}
+
 	if rangeHeader == "" {
 		start = 0
 		end = file.FileSize - 1

types/file.go

@@ -1,6 +1,13 @@
 package types
 
-import "github.com/gotd/td/tg"
+import (
+	"bytes"
+	"crypto/md5"
+	"encoding/gob"
+	"fmt"
+
+	"github.com/gotd/td/tg"
+)
 
 type File struct {
 	Location *tg.InputDocumentFileLocation
@@ -9,3 +16,21 @@ type File struct {
 	MimeType string
 	ID       int64
 }
+
+type HashableFileStruct struct {
+	FileName string
+	FileSize int64
+	MimeType string
+	FileID   int64
+}
+
+func (f *HashableFileStruct) Pack() string {
+	var b bytes.Buffer
+	gob.NewEncoder(&b).Encode(f)
+	return FromBytes(b.Bytes())
+}
+
+func FromBytes(data []byte) string {
+	result := md5.Sum(data)
+	return fmt.Sprintf("%x", result)
+}

utils/hashing.go

@@ -0,0 +1,18 @@
+package utils
+
+import (
+	"EverythingSuckz/fsb/config"
+	"EverythingSuckz/fsb/types"
+)
+
+func PackFile(fileName string, fileSize int64, mimeType string, fileID int64) string {
+	return (&types.HashableFileStruct{FileName: fileName, FileSize: fileSize, MimeType: mimeType, FileID: fileID}).Pack()
+}
+
+func GetShortHash(fullHash string) string {
+	return fullHash[:config.ValueOf.HashLength]
+}
+
+func CheckHash(inputHash string, expectedHash string) bool {
+	return inputHash == GetShortHash(expectedHash)
+}