git.r.bdr.sh - rbdr/mobius/blob - hotline/transaction_handlers.go

   1 package hotline
   2
   3 import (
   4         "bytes"
   5         "encoding/binary"
   6         "errors"
   7         "fmt"
   8         "gopkg.in/yaml.v3"
   9         "math/big"
  10         "os"
  11         "path"
  12         "path/filepath"
  13         "sort"
  14         "strings"
  15         "time"
  16 )
  17
  18 type HandlerFunc func(*ClientConn, *Transaction) ([]Transaction, error)
  19
  20 type TransactionType struct {
  21         Handler        HandlerFunc // function for handling the transaction type
  22         Name           string      // Name of transaction as it will appear in logging
  23         RequiredFields []requiredField
  24 }
  25
  26 var TransactionHandlers = map[uint16]TransactionType{
  27         // Server initiated
  28         TranChatMsg: {
  29                 Name: "TranChatMsg",
  30         },
  31         // Server initiated
  32         TranNotifyChangeUser: {
  33                 Name: "TranNotifyChangeUser",
  34         },
  35         TranError: {
  36                 Name: "TranError",
  37         },
  38         TranShowAgreement: {
  39                 Name: "TranShowAgreement",
  40         },
  41         TranUserAccess: {
  42                 Name: "TranUserAccess",
  43         },
  44         TranNotifyDeleteUser: {
  45                 Name: "TranNotifyDeleteUser",
  46         },
  47         TranAgreed: {
  48                 Name:    "TranAgreed",
  49                 Handler: HandleTranAgreed,
  50         },
  51         TranChatSend: {
  52                 Name:    "TranChatSend",
  53                 Handler: HandleChatSend,
  54                 RequiredFields: []requiredField{
  55                         {
  56                                 ID:     FieldData,
  57                                 minLen: 0,
  58                         },
  59                 },
  60         },
  61         TranDelNewsArt: {
  62                 Name:    "TranDelNewsArt",
  63                 Handler: HandleDelNewsArt,
  64         },
  65         TranDelNewsItem: {
  66                 Name:    "TranDelNewsItem",
  67                 Handler: HandleDelNewsItem,
  68         },
  69         TranDeleteFile: {
  70                 Name:    "TranDeleteFile",
  71                 Handler: HandleDeleteFile,
  72         },
  73         TranDeleteUser: {
  74                 Name:    "TranDeleteUser",
  75                 Handler: HandleDeleteUser,
  76         },
  77         TranDisconnectUser: {
  78                 Name:    "TranDisconnectUser",
  79                 Handler: HandleDisconnectUser,
  80         },
  81         TranDownloadFile: {
  82                 Name:    "TranDownloadFile",
  83                 Handler: HandleDownloadFile,
  84         },
  85         TranDownloadFldr: {
  86                 Name:    "TranDownloadFldr",
  87                 Handler: HandleDownloadFolder,
  88         },
  89         TranGetClientInfoText: {
  90                 Name:    "TranGetClientInfoText",
  91                 Handler: HandleGetClientInfoText,
  92         },
  93         TranGetFileInfo: {
  94                 Name:    "TranGetFileInfo",
  95                 Handler: HandleGetFileInfo,
  96         },
  97         TranGetFileNameList: {
  98                 Name:    "TranGetFileNameList",
  99                 Handler: HandleGetFileNameList,
 100         },
 101         TranGetMsgs: {
 102                 Name:    "TranGetMsgs",
 103                 Handler: HandleGetMsgs,
 104         },
 105         TranGetNewsArtData: {
 106                 Name:    "TranGetNewsArtData",
 107                 Handler: HandleGetNewsArtData,
 108         },
 109         TranGetNewsArtNameList: {
 110                 Name:    "TranGetNewsArtNameList",
 111                 Handler: HandleGetNewsArtNameList,
 112         },
 113         TranGetNewsCatNameList: {
 114                 Name:    "TranGetNewsCatNameList",
 115                 Handler: HandleGetNewsCatNameList,
 116         },
 117         TranGetUser: {
 118                 Name:    "TranGetUser",
 119                 Handler: HandleGetUser,
 120         },
 121         TranGetUserNameList: {
 122                 Name:    "tranHandleGetUserNameList",
 123                 Handler: HandleGetUserNameList,
 124         },
 125         TranInviteNewChat: {
 126                 Name:    "TranInviteNewChat",
 127                 Handler: HandleInviteNewChat,
 128         },
 129         TranInviteToChat: {
 130                 Name:    "TranInviteToChat",
 131                 Handler: HandleInviteToChat,
 132         },
 133         TranJoinChat: {
 134                 Name:    "TranJoinChat",
 135                 Handler: HandleJoinChat,
 136         },
 137         TranKeepAlive: {
 138                 Name:    "TranKeepAlive",
 139                 Handler: HandleKeepAlive,
 140         },
 141         TranLeaveChat: {
 142                 Name:    "TranJoinChat",
 143                 Handler: HandleLeaveChat,
 144         },
 145         TranListUsers: {
 146                 Name:    "TranListUsers",
 147                 Handler: HandleListUsers,
 148         },
 149         TranMoveFile: {
 150                 Name:    "TranMoveFile",
 151                 Handler: HandleMoveFile,
 152         },
 153         TranNewFolder: {
 154                 Name:    "TranNewFolder",
 155                 Handler: HandleNewFolder,
 156         },
 157         TranNewNewsCat: {
 158                 Name:    "TranNewNewsCat",
 159                 Handler: HandleNewNewsCat,
 160         },
 161         TranNewNewsFldr: {
 162                 Name:    "TranNewNewsFldr",
 163                 Handler: HandleNewNewsFldr,
 164         },
 165         TranNewUser: {
 166                 Name:    "TranNewUser",
 167                 Handler: HandleNewUser,
 168         },
 169         TranUpdateUser: {
 170                 Name:    "TranUpdateUser",
 171                 Handler: HandleUpdateUser,
 172         },
 173         TranOldPostNews: {
 174                 Name:    "TranOldPostNews",
 175                 Handler: HandleTranOldPostNews,
 176         },
 177         TranPostNewsArt: {
 178                 Name:    "TranPostNewsArt",
 179                 Handler: HandlePostNewsArt,
 180         },
 181         TranRejectChatInvite: {
 182                 Name:    "TranRejectChatInvite",
 183                 Handler: HandleRejectChatInvite,
 184         },
 185         TranSendInstantMsg: {
 186                 Name:    "TranSendInstantMsg",
 187                 Handler: HandleSendInstantMsg,
 188                 RequiredFields: []requiredField{
 189                         {
 190                                 ID:     FieldData,
 191                                 minLen: 0,
 192                         },
 193                         {
 194                                 ID: FieldUserID,
 195                         },
 196                 },
 197         },
 198         TranSetChatSubject: {
 199                 Name:    "TranSetChatSubject",
 200                 Handler: HandleSetChatSubject,
 201         },
 202         TranMakeFileAlias: {
 203                 Name:    "TranMakeFileAlias",
 204                 Handler: HandleMakeAlias,
 205                 RequiredFields: []requiredField{
 206                         {ID: FieldFileName, minLen: 1},
 207                         {ID: FieldFilePath, minLen: 1},
 208                         {ID: FieldFileNewPath, minLen: 1},
 209                 },
 210         },
 211         TranSetClientUserInfo: {
 212                 Name:    "TranSetClientUserInfo",
 213                 Handler: HandleSetClientUserInfo,
 214         },
 215         TranSetFileInfo: {
 216                 Name:    "TranSetFileInfo",
 217                 Handler: HandleSetFileInfo,
 218         },
 219         TranSetUser: {
 220                 Name:    "TranSetUser",
 221                 Handler: HandleSetUser,
 222         },
 223         TranUploadFile: {
 224                 Name:    "TranUploadFile",
 225                 Handler: HandleUploadFile,
 226         },
 227         TranUploadFldr: {
 228                 Name:    "TranUploadFldr",
 229                 Handler: HandleUploadFolder,
 230         },
 231         TranUserBroadcast: {
 232                 Name:    "TranUserBroadcast",
 233                 Handler: HandleUserBroadcast,
 234         },
 235         TranDownloadBanner: {
 236                 Name:    "TranDownloadBanner",
 237                 Handler: HandleDownloadBanner,
 238         },
 239 }
 240
 241 func HandleChatSend(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 242         if !cc.Authorize(accessSendChat) {
 243                 res = append(res, cc.NewErrReply(t, "You are not allowed to participate in chat."))
 244                 return res, err
 245         }
 246
 247         // Truncate long usernames
 248         trunc := fmt.Sprintf("%13s", cc.UserName)
 249         formattedMsg := fmt.Sprintf("\r%.14s:  %s", trunc, t.GetField(FieldData).Data)
 250
 251         // By holding the option key, Hotline chat allows users to send /me formatted messages like:
 252         // *** Halcyon does stuff
 253         // This is indicated by the presence of the optional field FieldChatOptions set to a value of 1.
 254         // Most clients do not send this option for normal chat messages.
 255         if t.GetField(FieldChatOptions).Data != nil && bytes.Equal(t.GetField(FieldChatOptions).Data, []byte{0, 1}) {
 256                 formattedMsg = fmt.Sprintf("\r*** %s %s", cc.UserName, t.GetField(FieldData).Data)
 257         }
 258
 259         // The ChatID field is used to identify messages as belonging to a private chat.
 260         // All clients *except* Frogblast omit this field for public chat, but Frogblast sends a value of 00 00 00 00.
 261         chatID := t.GetField(FieldChatID).Data
 262         if chatID != nil && !bytes.Equal([]byte{0, 0, 0, 0}, chatID) {
 263                 chatInt := binary.BigEndian.Uint32(chatID)
 264                 privChat := cc.Server.PrivateChats[chatInt]
 265
 266                 clients := sortedClients(privChat.ClientConn)
 267
 268                 // send the message to all connected clients of the private chat
 269                 for _, c := range clients {
 270                         res = append(res, *NewTransaction(
 271                                 TranChatMsg,
 272                                 c.ID,
 273                                 NewField(FieldChatID, chatID),
 274                                 NewField(FieldData, []byte(formattedMsg)),
 275                         ))
 276                 }
 277                 return res, err
 278         }
 279
 280         for _, c := range sortedClients(cc.Server.Clients) {
 281                 // Filter out clients that do not have the read chat permission
 282                 if c.Authorize(accessReadChat) {
 283                         res = append(res, *NewTransaction(TranChatMsg, c.ID, NewField(FieldData, []byte(formattedMsg))))
 284                 }
 285         }
 286
 287         return res, err
 288 }
 289
 290 // HandleSendInstantMsg sends instant message to the user on the current server.
 291 // Fields used in the request:
 292 //
 293 //      103     User ID
 294 //      113     Options
 295 //              One of the following values:
 296 //              - User message (myOpt_UserMessage = 1)
 297 //              - Refuse message (myOpt_RefuseMessage = 2)
 298 //              - Refuse chat (myOpt_RefuseChat  = 3)
 299 //              - Automatic response (myOpt_AutomaticResponse = 4)"
 300 //      101     Data    Optional
 301 //      214     Quoting message Optional
 302 //
 303 // Fields used in the reply:
 304 // None
 305 func HandleSendInstantMsg(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 306         if !cc.Authorize(accessSendPrivMsg) {
 307                 res = append(res, cc.NewErrReply(t, "You are not allowed to send private messages."))
 308                 return res, errors.New("user is not allowed to send private messages")
 309         }
 310
 311         msg := t.GetField(FieldData)
 312         ID := t.GetField(FieldUserID)
 313
 314         reply := NewTransaction(
 315                 TranServerMsg,
 316                 &ID.Data,
 317                 NewField(FieldData, msg.Data),
 318                 NewField(FieldUserName, cc.UserName),
 319                 NewField(FieldUserID, *cc.ID),
 320                 NewField(FieldOptions, []byte{0, 1}),
 321         )
 322
 323         // Later versions of Hotline include the original message in the FieldQuotingMsg field so
 324         //  the receiving client can display both the received message and what it is in reply to
 325         if t.GetField(FieldQuotingMsg).Data != nil {
 326                 reply.Fields = append(reply.Fields, NewField(FieldQuotingMsg, t.GetField(FieldQuotingMsg).Data))
 327         }
 328
 329         id, err := byteToInt(ID.Data)
 330         if err != nil {
 331                 return res, errors.New("invalid client ID")
 332         }
 333         otherClient, ok := cc.Server.Clients[uint16(id)]
 334         if !ok {
 335                 return res, errors.New("invalid client ID")
 336         }
 337
 338         // Check if target user has "Refuse private messages" flag
 339         flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(otherClient.Flags)))
 340         if flagBitmap.Bit(UserFlagRefusePM) == 1 {
 341                 res = append(res,
 342                         *NewTransaction(
 343                                 TranServerMsg,
 344                                 cc.ID,
 345                                 NewField(FieldData, []byte(string(otherClient.UserName)+" does not accept private messages.")),
 346                                 NewField(FieldUserName, otherClient.UserName),
 347                                 NewField(FieldUserID, *otherClient.ID),
 348                                 NewField(FieldOptions, []byte{0, 2}),
 349                         ),
 350                 )
 351         } else {
 352                 res = append(res, *reply)
 353         }
 354
 355         // Respond with auto reply if other client has it enabled
 356         if len(otherClient.AutoReply) > 0 {
 357                 res = append(res,
 358                         *NewTransaction(
 359                                 TranServerMsg,
 360                                 cc.ID,
 361                                 NewField(FieldData, otherClient.AutoReply),
 362                                 NewField(FieldUserName, otherClient.UserName),
 363                                 NewField(FieldUserID, *otherClient.ID),
 364                                 NewField(FieldOptions, []byte{0, 1}),
 365                         ),
 366                 )
 367         }
 368
 369         res = append(res, cc.NewReply(t))
 370
 371         return res, err
 372 }
 373
 374 func HandleGetFileInfo(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 375         fileName := t.GetField(FieldFileName).Data
 376         filePath := t.GetField(FieldFilePath).Data
 377
 378         fullFilePath, err := readPath(cc.Server.Config.FileRoot, filePath, fileName)
 379         if err != nil {
 380                 return res, err
 381         }
 382
 383         fw, err := newFileWrapper(cc.Server.FS, fullFilePath, 0)
 384         if err != nil {
 385                 return res, err
 386         }
 387
 388         encodedName, err := txtEncoder.String(fw.name)
 389         if err != nil {
 390                 return res, fmt.Errorf("invalid filepath encoding: %w", err)
 391         }
 392
 393         fields := []Field{
 394                 NewField(FieldFileName, []byte(encodedName)),
 395                 NewField(FieldFileTypeString, fw.ffo.FlatFileInformationFork.friendlyType()),
 396                 NewField(FieldFileCreatorString, fw.ffo.FlatFileInformationFork.friendlyCreator()),
 397                 NewField(FieldFileType, fw.ffo.FlatFileInformationFork.TypeSignature),
 398                 NewField(FieldFileCreateDate, fw.ffo.FlatFileInformationFork.CreateDate),
 399                 NewField(FieldFileModifyDate, fw.ffo.FlatFileInformationFork.ModifyDate),
 400         }
 401
 402         // Include the optional FileComment field if there is a comment.
 403         if len(fw.ffo.FlatFileInformationFork.Comment) != 0 {
 404                 fields = append(fields, NewField(FieldFileComment, fw.ffo.FlatFileInformationFork.Comment))
 405         }
 406
 407         // Include the FileSize field for files.
 408         if !bytes.Equal(fw.ffo.FlatFileInformationFork.TypeSignature, []byte{0x66, 0x6c, 0x64, 0x72}) {
 409                 fields = append(fields, NewField(FieldFileSize, fw.totalSize()))
 410         }
 411
 412         res = append(res, cc.NewReply(t, fields...))
 413         return res, err
 414 }
 415
 416 // HandleSetFileInfo updates a file or folder name and/or comment from the Get Info window
 417 // Fields used in the request:
 418 // * 201        File name
 419 // * 202        File path       Optional
 420 // * 211        File new name   Optional
 421 // * 210        File comment    Optional
 422 // Fields used in the reply:    None
 423 func HandleSetFileInfo(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 424         fileName := t.GetField(FieldFileName).Data
 425         filePath := t.GetField(FieldFilePath).Data
 426
 427         fullFilePath, err := readPath(cc.Server.Config.FileRoot, filePath, fileName)
 428         if err != nil {
 429                 return res, err
 430         }
 431
 432         fi, err := cc.Server.FS.Stat(fullFilePath)
 433         if err != nil {
 434                 return res, err
 435         }
 436
 437         hlFile, err := newFileWrapper(cc.Server.FS, fullFilePath, 0)
 438         if err != nil {
 439                 return res, err
 440         }
 441         if t.GetField(FieldFileComment).Data != nil {
 442                 switch mode := fi.Mode(); {
 443                 case mode.IsDir():
 444                         if !cc.Authorize(accessSetFolderComment) {
 445                                 res = append(res, cc.NewErrReply(t, "You are not allowed to set comments for folders."))
 446                                 return res, err
 447                         }
 448                 case mode.IsRegular():
 449                         if !cc.Authorize(accessSetFileComment) {
 450                                 res = append(res, cc.NewErrReply(t, "You are not allowed to set comments for files."))
 451                                 return res, err
 452                         }
 453                 }
 454
 455                 if err := hlFile.ffo.FlatFileInformationFork.setComment(t.GetField(FieldFileComment).Data); err != nil {
 456                         return res, err
 457                 }
 458                 w, err := hlFile.infoForkWriter()
 459                 if err != nil {
 460                         return res, err
 461                 }
 462                 _, err = w.Write(hlFile.ffo.FlatFileInformationFork.MarshalBinary())
 463                 if err != nil {
 464                         return res, err
 465                 }
 466         }
 467
 468         fullNewFilePath, err := readPath(cc.Server.Config.FileRoot, filePath, t.GetField(FieldFileNewName).Data)
 469         if err != nil {
 470                 return nil, err
 471         }
 472
 473         fileNewName := t.GetField(FieldFileNewName).Data
 474
 475         if fileNewName != nil {
 476                 switch mode := fi.Mode(); {
 477                 case mode.IsDir():
 478                         if !cc.Authorize(accessRenameFolder) {
 479                                 res = append(res, cc.NewErrReply(t, "You are not allowed to rename folders."))
 480                                 return res, err
 481                         }
 482                         err = os.Rename(fullFilePath, fullNewFilePath)
 483                         if os.IsNotExist(err) {
 484                                 res = append(res, cc.NewErrReply(t, "Cannot rename folder "+string(fileName)+" because it does not exist or cannot be found."))
 485                                 return res, err
 486                         }
 487                 case mode.IsRegular():
 488                         if !cc.Authorize(accessRenameFile) {
 489                                 res = append(res, cc.NewErrReply(t, "You are not allowed to rename files."))
 490                                 return res, err
 491                         }
 492                         fileDir, err := readPath(cc.Server.Config.FileRoot, filePath, []byte{})
 493                         if err != nil {
 494                                 return nil, err
 495                         }
 496                         hlFile.name, err = txtDecoder.String(string(fileNewName))
 497                         if err != nil {
 498                                 return res, fmt.Errorf("invalid filepath encoding: %w", err)
 499                         }
 500
 501                         err = hlFile.move(fileDir)
 502                         if os.IsNotExist(err) {
 503                                 res = append(res, cc.NewErrReply(t, "Cannot rename file "+string(fileName)+" because it does not exist or cannot be found."))
 504                                 return res, err
 505                         }
 506                         if err != nil {
 507                                 return res, err
 508                         }
 509                 }
 510         }
 511
 512         res = append(res, cc.NewReply(t))
 513         return res, err
 514 }
 515
 516 // HandleDeleteFile deletes a file or folder
 517 // Fields used in the request:
 518 // * 201        File name
 519 // * 202        File path
 520 // Fields used in the reply: none
 521 func HandleDeleteFile(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 522         fileName := t.GetField(FieldFileName).Data
 523         filePath := t.GetField(FieldFilePath).Data
 524
 525         fullFilePath, err := readPath(cc.Server.Config.FileRoot, filePath, fileName)
 526         if err != nil {
 527                 return res, err
 528         }
 529
 530         hlFile, err := newFileWrapper(cc.Server.FS, fullFilePath, 0)
 531         if err != nil {
 532                 return res, err
 533         }
 534
 535         fi, err := hlFile.dataFile()
 536         if err != nil {
 537                 res = append(res, cc.NewErrReply(t, "Cannot delete file "+string(fileName)+" because it does not exist or cannot be found."))
 538                 return res, nil
 539         }
 540
 541         switch mode := fi.Mode(); {
 542         case mode.IsDir():
 543                 if !cc.Authorize(accessDeleteFolder) {
 544                         res = append(res, cc.NewErrReply(t, "You are not allowed to delete folders."))
 545                         return res, err
 546                 }
 547         case mode.IsRegular():
 548                 if !cc.Authorize(accessDeleteFile) {
 549                         res = append(res, cc.NewErrReply(t, "You are not allowed to delete files."))
 550                         return res, err
 551                 }
 552         }
 553
 554         if err := hlFile.delete(); err != nil {
 555                 return res, err
 556         }
 557
 558         res = append(res, cc.NewReply(t))
 559         return res, err
 560 }
 561
 562 // HandleMoveFile moves files or folders. Note: seemingly not documented
 563 func HandleMoveFile(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 564         fileName := string(t.GetField(FieldFileName).Data)
 565
 566         filePath, err := readPath(cc.Server.Config.FileRoot, t.GetField(FieldFilePath).Data, t.GetField(FieldFileName).Data)
 567         if err != nil {
 568                 return res, err
 569         }
 570
 571         fileNewPath, err := readPath(cc.Server.Config.FileRoot, t.GetField(FieldFileNewPath).Data, nil)
 572         if err != nil {
 573                 return res, err
 574         }
 575
 576         cc.logger.Infow("Move file", "src", filePath+"/"+fileName, "dst", fileNewPath+"/"+fileName)
 577
 578         hlFile, err := newFileWrapper(cc.Server.FS, filePath, 0)
 579         if err != nil {
 580                 return res, err
 581         }
 582
 583         fi, err := hlFile.dataFile()
 584         if err != nil {
 585                 res = append(res, cc.NewErrReply(t, "Cannot delete file "+fileName+" because it does not exist or cannot be found."))
 586                 return res, err
 587         }
 588         switch mode := fi.Mode(); {
 589         case mode.IsDir():
 590                 if !cc.Authorize(accessMoveFolder) {
 591                         res = append(res, cc.NewErrReply(t, "You are not allowed to move folders."))
 592                         return res, err
 593                 }
 594         case mode.IsRegular():
 595                 if !cc.Authorize(accessMoveFile) {
 596                         res = append(res, cc.NewErrReply(t, "You are not allowed to move files."))
 597                         return res, err
 598                 }
 599         }
 600         if err := hlFile.move(fileNewPath); err != nil {
 601                 return res, err
 602         }
 603         // TODO: handle other possible errors; e.g. fileWrapper delete fails due to fileWrapper permission issue
 604
 605         res = append(res, cc.NewReply(t))
 606         return res, err
 607 }
 608
 609 func HandleNewFolder(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 610         if !cc.Authorize(accessCreateFolder) {
 611                 res = append(res, cc.NewErrReply(t, "You are not allowed to create folders."))
 612                 return res, err
 613         }
 614         folderName := string(t.GetField(FieldFileName).Data)
 615
 616         folderName = path.Join("/", folderName)
 617
 618         var subPath string
 619
 620         // FieldFilePath is only present for nested paths
 621         if t.GetField(FieldFilePath).Data != nil {
 622                 var newFp FilePath
 623                 _, err := newFp.Write(t.GetField(FieldFilePath).Data)
 624                 if err != nil {
 625                         return nil, err
 626                 }
 627
 628                 for _, pathItem := range newFp.Items {
 629                         subPath = filepath.Join("/", subPath, string(pathItem.Name))
 630                 }
 631         }
 632         newFolderPath := path.Join(cc.Server.Config.FileRoot, subPath, folderName)
 633         newFolderPath, err = txtDecoder.String(newFolderPath)
 634         if err != nil {
 635                 return res, fmt.Errorf("invalid filepath encoding: %w", err)
 636         }
 637
 638         // TODO: check path and folder name lengths
 639
 640         if _, err := cc.Server.FS.Stat(newFolderPath); !os.IsNotExist(err) {
 641                 msg := fmt.Sprintf("Cannot create folder \"%s\" because there is already a file or folder with that name.", folderName)
 642                 return []Transaction{cc.NewErrReply(t, msg)}, nil
 643         }
 644
 645         if err := cc.Server.FS.Mkdir(newFolderPath, 0777); err != nil {
 646                 msg := fmt.Sprintf("Cannot create folder \"%s\" because an error occurred.", folderName)
 647                 return []Transaction{cc.NewErrReply(t, msg)}, nil
 648         }
 649
 650         res = append(res, cc.NewReply(t))
 651         return res, err
 652 }
 653
 654 func HandleSetUser(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 655         if !cc.Authorize(accessModifyUser) {
 656                 res = append(res, cc.NewErrReply(t, "You are not allowed to modify accounts."))
 657                 return res, err
 658         }
 659
 660         login := decodeString(t.GetField(FieldUserLogin).Data)
 661         userName := string(t.GetField(FieldUserName).Data)
 662
 663         newAccessLvl := t.GetField(FieldUserAccess).Data
 664
 665         account := cc.Server.Accounts[login]
 666         account.Name = userName
 667         copy(account.Access[:], newAccessLvl)
 668
 669         // If the password field is cleared in the Hotline edit user UI, the SetUser transaction does
 670         // not include FieldUserPassword
 671         if t.GetField(FieldUserPassword).Data == nil {
 672                 account.Password = hashAndSalt([]byte(""))
 673         }
 674         if len(t.GetField(FieldUserPassword).Data) > 1 {
 675                 account.Password = hashAndSalt(t.GetField(FieldUserPassword).Data)
 676         }
 677
 678         out, err := yaml.Marshal(&account)
 679         if err != nil {
 680                 return res, err
 681         }
 682         if err := os.WriteFile(filepath.Join(cc.Server.ConfigDir, "Users", login+".yaml"), out, 0666); err != nil {
 683                 return res, err
 684         }
 685
 686         // Notify connected clients logged in as the user of the new access level
 687         for _, c := range cc.Server.Clients {
 688                 if c.Account.Login == login {
 689                         // Note: comment out these two lines to test server-side deny messages
 690                         newT := NewTransaction(TranUserAccess, c.ID, NewField(FieldUserAccess, newAccessLvl))
 691                         res = append(res, *newT)
 692
 693                         flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(c.Flags)))
 694                         if c.Authorize(accessDisconUser) {
 695                                 flagBitmap.SetBit(flagBitmap, UserFlagAdmin, 1)
 696                         } else {
 697                                 flagBitmap.SetBit(flagBitmap, UserFlagAdmin, 0)
 698                         }
 699                         binary.BigEndian.PutUint16(c.Flags, uint16(flagBitmap.Int64()))
 700
 701                         c.Account.Access = account.Access
 702
 703                         cc.sendAll(
 704                                 TranNotifyChangeUser,
 705                                 NewField(FieldUserID, *c.ID),
 706                                 NewField(FieldUserFlags, c.Flags),
 707                                 NewField(FieldUserName, c.UserName),
 708                                 NewField(FieldUserIconID, c.Icon),
 709                         )
 710                 }
 711         }
 712
 713         res = append(res, cc.NewReply(t))
 714         return res, err
 715 }
 716
 717 func HandleGetUser(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 718         if !cc.Authorize(accessOpenUser) {
 719                 res = append(res, cc.NewErrReply(t, "You are not allowed to view accounts."))
 720                 return res, err
 721         }
 722
 723         account := cc.Server.Accounts[string(t.GetField(FieldUserLogin).Data)]
 724         if account == nil {
 725                 res = append(res, cc.NewErrReply(t, "Account does not exist."))
 726                 return res, err
 727         }
 728
 729         res = append(res, cc.NewReply(t,
 730                 NewField(FieldUserName, []byte(account.Name)),
 731                 NewField(FieldUserLogin, encodeString(t.GetField(FieldUserLogin).Data)),
 732                 NewField(FieldUserPassword, []byte(account.Password)),
 733                 NewField(FieldUserAccess, account.Access[:]),
 734         ))
 735         return res, err
 736 }
 737
 738 func HandleListUsers(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 739         if !cc.Authorize(accessOpenUser) {
 740                 res = append(res, cc.NewErrReply(t, "You are not allowed to view accounts."))
 741                 return res, err
 742         }
 743
 744         var userFields []Field
 745         for _, acc := range cc.Server.Accounts {
 746                 b := make([]byte, 0, 100)
 747                 n, err := acc.Read(b)
 748                 if err != nil {
 749                         return res, err
 750                 }
 751
 752                 userFields = append(userFields, NewField(FieldData, b[:n]))
 753         }
 754
 755         res = append(res, cc.NewReply(t, userFields...))
 756         return res, err
 757 }
 758
 759 // HandleUpdateUser is used by the v1.5+ multi-user editor to perform account editing for multiple users at a time.
 760 // An update can be a mix of these actions:
 761 // * Create user
 762 // * Delete user
 763 // * Modify user (including renaming the account login)
 764 //
 765 // The Transaction sent by the client includes one data field per user that was modified.  This data field in turn
 766 // contains another data field encoded in its payload with a varying number of sub fields depending on which action is
 767 // performed.  This seems to be the only place in the Hotline protocol where a data field contains another data field.
 768 func HandleUpdateUser(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 769         for _, field := range t.Fields {
 770                 subFields, err := ReadFields(field.Data[0:2], field.Data[2:])
 771                 if err != nil {
 772                         return res, err
 773                 }
 774
 775                 if len(subFields) == 1 {
 776                         login := decodeString(getField(FieldData, &subFields).Data)
 777                         cc.logger.Infow("DeleteUser", "login", login)
 778
 779                         if !cc.Authorize(accessDeleteUser) {
 780                                 res = append(res, cc.NewErrReply(t, "You are not allowed to delete accounts."))
 781                                 return res, err
 782                         }
 783
 784                         if err := cc.Server.DeleteUser(login); err != nil {
 785                                 return res, err
 786                         }
 787                         continue
 788                 }
 789
 790                 login := decodeString(getField(FieldUserLogin, &subFields).Data)
 791
 792                 // check if the login dataFile; if so, we know we are updating an existing user
 793                 if acc, ok := cc.Server.Accounts[login]; ok {
 794                         cc.logger.Infow("UpdateUser", "login", login)
 795
 796                         // account dataFile, so this is an update action
 797                         if !cc.Authorize(accessModifyUser) {
 798                                 res = append(res, cc.NewErrReply(t, "You are not allowed to modify accounts."))
 799                                 return res, err
 800                         }
 801
 802                         if getField(FieldUserPassword, &subFields) != nil {
 803                                 newPass := getField(FieldUserPassword, &subFields).Data
 804                                 acc.Password = hashAndSalt(newPass)
 805                         } else {
 806                                 acc.Password = hashAndSalt([]byte(""))
 807                         }
 808
 809                         if getField(FieldUserAccess, &subFields) != nil {
 810                                 copy(acc.Access[:], getField(FieldUserAccess, &subFields).Data)
 811                         }
 812
 813                         err = cc.Server.UpdateUser(
 814                                 decodeString(getField(FieldData, &subFields).Data),
 815                                 decodeString(getField(FieldUserLogin, &subFields).Data),
 816                                 string(getField(FieldUserName, &subFields).Data),
 817                                 acc.Password,
 818                                 acc.Access,
 819                         )
 820                         if err != nil {
 821                                 return res, err
 822                         }
 823                 } else {
 824                         cc.logger.Infow("CreateUser", "login", login)
 825
 826                         if !cc.Authorize(accessCreateUser) {
 827                                 res = append(res, cc.NewErrReply(t, "You are not allowed to create new accounts."))
 828                                 return res, err
 829                         }
 830
 831                         newAccess := accessBitmap{}
 832                         copy(newAccess[:], getField(FieldUserAccess, &subFields).Data)
 833
 834                         // Prevent account from creating new account with greater permission
 835                         for i := 0; i < 64; i++ {
 836                                 if newAccess.IsSet(i) {
 837                                         if !cc.Authorize(i) {
 838                                                 return append(res, cc.NewErrReply(t, "Cannot create account with more access than yourself.")), err
 839                                         }
 840                                 }
 841                         }
 842
 843                         err := cc.Server.NewUser(login, string(getField(FieldUserName, &subFields).Data), string(getField(FieldUserPassword, &subFields).Data), newAccess)
 844                         if err != nil {
 845                                 return []Transaction{}, err
 846                         }
 847                 }
 848         }
 849
 850         res = append(res, cc.NewReply(t))
 851         return res, err
 852 }
 853
 854 // HandleNewUser creates a new user account
 855 func HandleNewUser(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 856         if !cc.Authorize(accessCreateUser) {
 857                 res = append(res, cc.NewErrReply(t, "You are not allowed to create new accounts."))
 858                 return res, err
 859         }
 860
 861         login := decodeString(t.GetField(FieldUserLogin).Data)
 862
 863         // If the account already dataFile, reply with an error
 864         if _, ok := cc.Server.Accounts[login]; ok {
 865                 res = append(res, cc.NewErrReply(t, "Cannot create account "+login+" because there is already an account with that login."))
 866                 return res, err
 867         }
 868
 869         newAccess := accessBitmap{}
 870         copy(newAccess[:], t.GetField(FieldUserAccess).Data)
 871
 872         // Prevent account from creating new account with greater permission
 873         for i := 0; i < 64; i++ {
 874                 if newAccess.IsSet(i) {
 875                         if !cc.Authorize(i) {
 876                                 res = append(res, cc.NewErrReply(t, "Cannot create account with more access than yourself."))
 877                                 return res, err
 878                         }
 879                 }
 880         }
 881
 882         if err := cc.Server.NewUser(login, string(t.GetField(FieldUserName).Data), string(t.GetField(FieldUserPassword).Data), newAccess); err != nil {
 883                 return []Transaction{}, err
 884         }
 885
 886         res = append(res, cc.NewReply(t))
 887         return res, err
 888 }
 889
 890 func HandleDeleteUser(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 891         if !cc.Authorize(accessDeleteUser) {
 892                 res = append(res, cc.NewErrReply(t, "You are not allowed to delete accounts."))
 893                 return res, err
 894         }
 895
 896         // TODO: Handle case where account doesn't exist; e.g. delete race condition
 897         login := decodeString(t.GetField(FieldUserLogin).Data)
 898
 899         if err := cc.Server.DeleteUser(login); err != nil {
 900                 return res, err
 901         }
 902
 903         res = append(res, cc.NewReply(t))
 904         return res, err
 905 }
 906
 907 // HandleUserBroadcast sends an Administrator Message to all connected clients of the server
 908 func HandleUserBroadcast(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 909         if !cc.Authorize(accessBroadcast) {
 910                 res = append(res, cc.NewErrReply(t, "You are not allowed to send broadcast messages."))
 911                 return res, err
 912         }
 913
 914         cc.sendAll(
 915                 TranServerMsg,
 916                 NewField(FieldData, t.GetField(TranGetMsgs).Data),
 917                 NewField(FieldChatOptions, []byte{0}),
 918         )
 919
 920         res = append(res, cc.NewReply(t))
 921         return res, err
 922 }
 923
 924 // HandleGetClientInfoText returns user information for the specific user.
 925 //
 926 // Fields used in the request:
 927 // 103  User ID
 928 //
 929 // Fields used in the reply:
 930 // 102  User name
 931 // 101  Data            User info text string
 932 func HandleGetClientInfoText(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 933         if !cc.Authorize(accessGetClientInfo) {
 934                 res = append(res, cc.NewErrReply(t, "You are not allowed to get client info."))
 935                 return res, err
 936         }
 937
 938         clientID, _ := byteToInt(t.GetField(FieldUserID).Data)
 939
 940         clientConn := cc.Server.Clients[uint16(clientID)]
 941         if clientConn == nil {
 942                 return append(res, cc.NewErrReply(t, "User not found.")), err
 943         }
 944
 945         res = append(res, cc.NewReply(t,
 946                 NewField(FieldData, []byte(clientConn.String())),
 947                 NewField(FieldUserName, clientConn.UserName),
 948         ))
 949         return res, err
 950 }
 951
 952 func HandleGetUserNameList(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 953         res = append(res, cc.NewReply(t, cc.Server.connectedUsers()...))
 954
 955         return res, err
 956 }
 957
 958 func HandleTranAgreed(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
 959         if t.GetField(FieldUserName).Data != nil {
 960                 if cc.Authorize(accessAnyName) {
 961                         cc.UserName = t.GetField(FieldUserName).Data
 962                 } else {
 963                         cc.UserName = []byte(cc.Account.Name)
 964                 }
 965         }
 966
 967         cc.Icon = t.GetField(FieldUserIconID).Data
 968
 969         cc.logger = cc.logger.With("name", string(cc.UserName))
 970         cc.logger.Infow("Login successful", "clientVersion", fmt.Sprintf("%v", func() int { i, _ := byteToInt(cc.Version); return i }()))
 971
 972         options := t.GetField(FieldOptions).Data
 973         optBitmap := big.NewInt(int64(binary.BigEndian.Uint16(options)))
 974
 975         flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(cc.Flags)))
 976
 977         // Check refuse private PM option
 978         if optBitmap.Bit(refusePM) == 1 {
 979                 flagBitmap.SetBit(flagBitmap, UserFlagRefusePM, 1)
 980                 binary.BigEndian.PutUint16(cc.Flags, uint16(flagBitmap.Int64()))
 981         }
 982
 983         // Check refuse private chat option
 984         if optBitmap.Bit(refuseChat) == 1 {
 985                 flagBitmap.SetBit(flagBitmap, UserFlagRefusePChat, 1)
 986                 binary.BigEndian.PutUint16(cc.Flags, uint16(flagBitmap.Int64()))
 987         }
 988
 989         // Check auto response
 990         if optBitmap.Bit(autoResponse) == 1 {
 991                 cc.AutoReply = t.GetField(FieldAutomaticResponse).Data
 992         } else {
 993                 cc.AutoReply = []byte{}
 994         }
 995
 996         trans := cc.notifyOthers(
 997                 *NewTransaction(
 998                         TranNotifyChangeUser, nil,
 999                         NewField(FieldUserName, cc.UserName),
1000                         NewField(FieldUserID, *cc.ID),
1001                         NewField(FieldUserIconID, cc.Icon),
1002                         NewField(FieldUserFlags, cc.Flags),
1003                 ),
1004         )
1005         res = append(res, trans...)
1006
1007         if cc.Server.Config.BannerFile != "" {
1008                 res = append(res, *NewTransaction(TranServerBanner, cc.ID, NewField(FieldBannerType, []byte("JPEG"))))
1009         }
1010
1011         res = append(res, cc.NewReply(t))
1012
1013         return res, err
1014 }
1015
1016 // HandleTranOldPostNews updates the flat news
1017 // Fields used in this request:
1018 // 101  Data
1019 func HandleTranOldPostNews(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1020         if !cc.Authorize(accessNewsPostArt) {
1021                 res = append(res, cc.NewErrReply(t, "You are not allowed to post news."))
1022                 return res, err
1023         }
1024
1025         cc.Server.flatNewsMux.Lock()
1026         defer cc.Server.flatNewsMux.Unlock()
1027
1028         newsDateTemplate := defaultNewsDateFormat
1029         if cc.Server.Config.NewsDateFormat != "" {
1030                 newsDateTemplate = cc.Server.Config.NewsDateFormat
1031         }
1032
1033         newsTemplate := defaultNewsTemplate
1034         if cc.Server.Config.NewsDelimiter != "" {
1035                 newsTemplate = cc.Server.Config.NewsDelimiter
1036         }
1037
1038         newsPost := fmt.Sprintf(newsTemplate+"\r", cc.UserName, time.Now().Format(newsDateTemplate), t.GetField(FieldData).Data)
1039         newsPost = strings.ReplaceAll(newsPost, "\n", "\r")
1040
1041         // update news in memory
1042         cc.Server.FlatNews = append([]byte(newsPost), cc.Server.FlatNews...)
1043
1044         // update news on disk
1045         if err := cc.Server.FS.WriteFile(filepath.Join(cc.Server.ConfigDir, "MessageBoard.txt"), cc.Server.FlatNews, 0644); err != nil {
1046                 return res, err
1047         }
1048
1049         // Notify all clients of updated news
1050         cc.sendAll(
1051                 TranNewMsg,
1052                 NewField(FieldData, []byte(newsPost)),
1053         )
1054
1055         res = append(res, cc.NewReply(t))
1056         return res, err
1057 }
1058
1059 func HandleDisconnectUser(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1060         if !cc.Authorize(accessDisconUser) {
1061                 res = append(res, cc.NewErrReply(t, "You are not allowed to disconnect users."))
1062                 return res, err
1063         }
1064
1065         clientConn := cc.Server.Clients[binary.BigEndian.Uint16(t.GetField(FieldUserID).Data)]
1066
1067         if clientConn.Authorize(accessCannotBeDiscon) {
1068                 res = append(res, cc.NewErrReply(t, clientConn.Account.Login+" is not allowed to be disconnected."))
1069                 return res, err
1070         }
1071
1072         // If FieldOptions is set, then the client IP is banned in addition to disconnected.
1073         // 00 01 = temporary ban
1074         // 00 02 = permanent ban
1075         if t.GetField(FieldOptions).Data != nil {
1076                 switch t.GetField(FieldOptions).Data[1] {
1077                 case 1:
1078                         // send message: "You are temporarily banned on this server"
1079                         cc.logger.Infow("Disconnect & temporarily ban " + string(clientConn.UserName))
1080
1081                         res = append(res, *NewTransaction(
1082                                 TranServerMsg,
1083                                 clientConn.ID,
1084                                 NewField(FieldData, []byte("You are temporarily banned on this server")),
1085                                 NewField(FieldChatOptions, []byte{0, 0}),
1086                         ))
1087
1088                         banUntil := time.Now().Add(tempBanDuration)
1089                         cc.Server.banList[strings.Split(clientConn.RemoteAddr, ":")[0]] = &banUntil
1090                 case 2:
1091                         // send message: "You are permanently banned on this server"
1092                         cc.logger.Infow("Disconnect & ban " + string(clientConn.UserName))
1093
1094                         res = append(res, *NewTransaction(
1095                                 TranServerMsg,
1096                                 clientConn.ID,
1097                                 NewField(FieldData, []byte("You are permanently banned on this server")),
1098                                 NewField(FieldChatOptions, []byte{0, 0}),
1099                         ))
1100
1101                         cc.Server.banList[strings.Split(clientConn.RemoteAddr, ":")[0]] = nil
1102                 }
1103
1104                 err := cc.Server.writeBanList()
1105                 if err != nil {
1106                         return res, err
1107                 }
1108         }
1109
1110         // TODO: remove this awful hack
1111         go func() {
1112                 time.Sleep(1 * time.Second)
1113                 clientConn.Disconnect()
1114         }()
1115
1116         return append(res, cc.NewReply(t)), err
1117 }
1118
1119 // HandleGetNewsCatNameList returns a list of news categories for a path
1120 // Fields used in the request:
1121 // 325  News path       (Optional)
1122 func HandleGetNewsCatNameList(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1123         if !cc.Authorize(accessNewsReadArt) {
1124                 res = append(res, cc.NewErrReply(t, "You are not allowed to read news."))
1125                 return res, err
1126         }
1127
1128         pathStrs := ReadNewsPath(t.GetField(FieldNewsPath).Data)
1129         cats := cc.Server.GetNewsCatByPath(pathStrs)
1130
1131         // To store the keys in slice in sorted order
1132         keys := make([]string, len(cats))
1133         i := 0
1134         for k := range cats {
1135                 keys[i] = k
1136                 i++
1137         }
1138         sort.Strings(keys)
1139
1140         var fieldData []Field
1141         for _, k := range keys {
1142                 cat := cats[k]
1143                 b, _ := cat.MarshalBinary()
1144                 fieldData = append(fieldData, NewField(
1145                         FieldNewsCatListData15,
1146                         b,
1147                 ))
1148         }
1149
1150         res = append(res, cc.NewReply(t, fieldData...))
1151         return res, err
1152 }
1153
1154 func HandleNewNewsCat(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1155         if !cc.Authorize(accessNewsCreateCat) {
1156                 res = append(res, cc.NewErrReply(t, "You are not allowed to create news categories."))
1157                 return res, err
1158         }
1159
1160         name := string(t.GetField(FieldNewsCatName).Data)
1161         pathStrs := ReadNewsPath(t.GetField(FieldNewsPath).Data)
1162
1163         cats := cc.Server.GetNewsCatByPath(pathStrs)
1164         cats[name] = NewsCategoryListData15{
1165                 Name:     name,
1166                 Type:     []byte{0, 3},
1167                 Articles: map[uint32]*NewsArtData{},
1168                 SubCats:  make(map[string]NewsCategoryListData15),
1169         }
1170
1171         if err := cc.Server.writeThreadedNews(); err != nil {
1172                 return res, err
1173         }
1174         res = append(res, cc.NewReply(t))
1175         return res, err
1176 }
1177
1178 // Fields used in the request:
1179 // 322  News category name
1180 // 325  News path
1181 func HandleNewNewsFldr(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1182         if !cc.Authorize(accessNewsCreateFldr) {
1183                 res = append(res, cc.NewErrReply(t, "You are not allowed to create news folders."))
1184                 return res, err
1185         }
1186
1187         name := string(t.GetField(FieldFileName).Data)
1188         pathStrs := ReadNewsPath(t.GetField(FieldNewsPath).Data)
1189
1190         cc.logger.Infof("Creating new news folder %s", name)
1191
1192         cats := cc.Server.GetNewsCatByPath(pathStrs)
1193         cats[name] = NewsCategoryListData15{
1194                 Name:     name,
1195                 Type:     []byte{0, 2},
1196                 Articles: map[uint32]*NewsArtData{},
1197                 SubCats:  make(map[string]NewsCategoryListData15),
1198         }
1199         if err := cc.Server.writeThreadedNews(); err != nil {
1200                 return res, err
1201         }
1202         res = append(res, cc.NewReply(t))
1203         return res, err
1204 }
1205
1206 // HandleGetNewsArtData gets the list of article names at the specified news path.
1207
1208 // Fields used in the request:
1209 // 325  News path       Optional
1210
1211 // Fields used in the reply:
1212 // 321  News article list data  Optional
1213 func HandleGetNewsArtNameList(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1214         if !cc.Authorize(accessNewsReadArt) {
1215                 res = append(res, cc.NewErrReply(t, "You are not allowed to read news."))
1216                 return res, err
1217         }
1218         pathStrs := ReadNewsPath(t.GetField(FieldNewsPath).Data)
1219
1220         var cat NewsCategoryListData15
1221         cats := cc.Server.ThreadedNews.Categories
1222
1223         for _, fp := range pathStrs {
1224                 cat = cats[fp]
1225                 cats = cats[fp].SubCats
1226         }
1227
1228         nald := cat.GetNewsArtListData()
1229
1230         res = append(res, cc.NewReply(t, NewField(FieldNewsArtListData, nald.Payload())))
1231         return res, err
1232 }
1233
1234 // HandleGetNewsArtData requests information about the specific news article.
1235 // Fields used in the request:
1236 //
1237 // Request fields
1238 // 325  News path
1239 // 326  News article ID
1240 // 327  News article data flavor
1241 //
1242 // Fields used in the reply:
1243 // 328  News article title
1244 // 329  News article poster
1245 // 330  News article date
1246 // 331  Previous article ID
1247 // 332  Next article ID
1248 // 335  Parent article ID
1249 // 336  First child article ID
1250 // 327  News article data flavor        "Should be “text/plain”
1251 // 333  News article data       Optional (if data flavor is “text/plain”)
1252 func HandleGetNewsArtData(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1253         if !cc.Authorize(accessNewsReadArt) {
1254                 res = append(res, cc.NewErrReply(t, "You are not allowed to read news."))
1255                 return res, err
1256         }
1257
1258         var cat NewsCategoryListData15
1259         cats := cc.Server.ThreadedNews.Categories
1260
1261         for _, fp := range ReadNewsPath(t.GetField(FieldNewsPath).Data) {
1262                 cat = cats[fp]
1263                 cats = cats[fp].SubCats
1264         }
1265
1266         // The official Hotline clients will send the article ID as 2 bytes if possible, but
1267         // some third party clients such as Frogblast and Heildrun will always send 4 bytes
1268         convertedID, err := byteToInt(t.GetField(FieldNewsArtID).Data)
1269         if err != nil {
1270                 return res, err
1271         }
1272
1273         art := cat.Articles[uint32(convertedID)]
1274         if art == nil {
1275                 res = append(res, cc.NewReply(t))
1276                 return res, err
1277         }
1278
1279         res = append(res, cc.NewReply(t,
1280                 NewField(FieldNewsArtTitle, []byte(art.Title)),
1281                 NewField(FieldNewsArtPoster, []byte(art.Poster)),
1282                 NewField(FieldNewsArtDate, art.Date),
1283                 NewField(FieldNewsArtPrevArt, art.PrevArt),
1284                 NewField(FieldNewsArtNextArt, art.NextArt),
1285                 NewField(FieldNewsArtParentArt, art.ParentArt),
1286                 NewField(FieldNewsArt1stChildArt, art.FirstChildArt),
1287                 NewField(FieldNewsArtDataFlav, []byte("text/plain")),
1288                 NewField(FieldNewsArtData, []byte(art.Data)),
1289         ))
1290         return res, err
1291 }
1292
1293 // HandleDelNewsItem deletes an existing threaded news folder or category from the server.
1294 // Fields used in the request:
1295 // 325  News path
1296 // Fields used in the reply:
1297 // None
1298 func HandleDelNewsItem(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1299         pathStrs := ReadNewsPath(t.GetField(FieldNewsPath).Data)
1300
1301         cats := cc.Server.ThreadedNews.Categories
1302         delName := pathStrs[len(pathStrs)-1]
1303         if len(pathStrs) > 1 {
1304                 for _, fp := range pathStrs[0 : len(pathStrs)-1] {
1305                         cats = cats[fp].SubCats
1306                 }
1307         }
1308
1309         if bytes.Equal(cats[delName].Type, []byte{0, 3}) {
1310                 if !cc.Authorize(accessNewsDeleteCat) {
1311                         return append(res, cc.NewErrReply(t, "You are not allowed to delete news categories.")), nil
1312                 }
1313         } else {
1314                 if !cc.Authorize(accessNewsDeleteFldr) {
1315                         return append(res, cc.NewErrReply(t, "You are not allowed to delete news folders.")), nil
1316                 }
1317         }
1318
1319         delete(cats, delName)
1320
1321         if err := cc.Server.writeThreadedNews(); err != nil {
1322                 return res, err
1323         }
1324
1325         return append(res, cc.NewReply(t)), nil
1326 }
1327
1328 func HandleDelNewsArt(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1329         if !cc.Authorize(accessNewsDeleteArt) {
1330                 res = append(res, cc.NewErrReply(t, "You are not allowed to delete news articles."))
1331                 return res, err
1332         }
1333
1334         // Request Fields
1335         // 325  News path
1336         // 326  News article ID
1337         // 337  News article – recursive delete       Delete child articles (1) or not (0)
1338         pathStrs := ReadNewsPath(t.GetField(FieldNewsPath).Data)
1339         ID, err := byteToInt(t.GetField(FieldNewsArtID).Data)
1340         if err != nil {
1341                 return res, err
1342         }
1343
1344         // TODO: Delete recursive
1345         cats := cc.Server.GetNewsCatByPath(pathStrs[:len(pathStrs)-1])
1346
1347         catName := pathStrs[len(pathStrs)-1]
1348         cat := cats[catName]
1349
1350         delete(cat.Articles, uint32(ID))
1351
1352         cats[catName] = cat
1353         if err := cc.Server.writeThreadedNews(); err != nil {
1354                 return res, err
1355         }
1356
1357         res = append(res, cc.NewReply(t))
1358         return res, err
1359 }
1360
1361 // Request fields
1362 // 325  News path
1363 // 326  News article ID                                                 ID of the parent article?
1364 // 328  News article title
1365 // 334  News article flags
1366 // 327  News article data flavor                Currently “text/plain”
1367 // 333  News article data
1368 func HandlePostNewsArt(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1369         if !cc.Authorize(accessNewsPostArt) {
1370                 res = append(res, cc.NewErrReply(t, "You are not allowed to post news articles."))
1371                 return res, err
1372         }
1373
1374         pathStrs := ReadNewsPath(t.GetField(FieldNewsPath).Data)
1375         cats := cc.Server.GetNewsCatByPath(pathStrs[:len(pathStrs)-1])
1376
1377         catName := pathStrs[len(pathStrs)-1]
1378         cat := cats[catName]
1379
1380         artID, err := byteToInt(t.GetField(FieldNewsArtID).Data)
1381         if err != nil {
1382                 return res, err
1383         }
1384         convertedArtID := uint32(artID)
1385         bs := make([]byte, 4)
1386         binary.BigEndian.PutUint32(bs, convertedArtID)
1387
1388         newArt := NewsArtData{
1389                 Title:         string(t.GetField(FieldNewsArtTitle).Data),
1390                 Poster:        string(cc.UserName),
1391                 Date:          toHotlineTime(time.Now()),
1392                 PrevArt:       []byte{0, 0, 0, 0},
1393                 NextArt:       []byte{0, 0, 0, 0},
1394                 ParentArt:     bs,
1395                 FirstChildArt: []byte{0, 0, 0, 0},
1396                 DataFlav:      []byte("text/plain"),
1397                 Data:          string(t.GetField(FieldNewsArtData).Data),
1398         }
1399
1400         var keys []int
1401         for k := range cat.Articles {
1402                 keys = append(keys, int(k))
1403         }
1404
1405         nextID := uint32(1)
1406         if len(keys) > 0 {
1407                 sort.Ints(keys)
1408                 prevID := uint32(keys[len(keys)-1])
1409                 nextID = prevID + 1
1410
1411                 binary.BigEndian.PutUint32(newArt.PrevArt, prevID)
1412
1413                 // Set next article ID
1414                 binary.BigEndian.PutUint32(cat.Articles[prevID].NextArt, nextID)
1415         }
1416
1417         // Update parent article with first child reply
1418         parentID := convertedArtID
1419         if parentID != 0 {
1420                 parentArt := cat.Articles[parentID]
1421
1422                 if bytes.Equal(parentArt.FirstChildArt, []byte{0, 0, 0, 0}) {
1423                         binary.BigEndian.PutUint32(parentArt.FirstChildArt, nextID)
1424                 }
1425         }
1426
1427         cat.Articles[nextID] = &newArt
1428
1429         cats[catName] = cat
1430         if err := cc.Server.writeThreadedNews(); err != nil {
1431                 return res, err
1432         }
1433
1434         res = append(res, cc.NewReply(t))
1435         return res, err
1436 }
1437
1438 // HandleGetMsgs returns the flat news data
1439 func HandleGetMsgs(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1440         if !cc.Authorize(accessNewsReadArt) {
1441                 res = append(res, cc.NewErrReply(t, "You are not allowed to read news."))
1442                 return res, err
1443         }
1444
1445         res = append(res, cc.NewReply(t, NewField(FieldData, cc.Server.FlatNews)))
1446
1447         return res, err
1448 }
1449
1450 func HandleDownloadFile(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1451         if !cc.Authorize(accessDownloadFile) {
1452                 res = append(res, cc.NewErrReply(t, "You are not allowed to download files."))
1453                 return res, err
1454         }
1455
1456         fileName := t.GetField(FieldFileName).Data
1457         filePath := t.GetField(FieldFilePath).Data
1458         resumeData := t.GetField(FieldFileResumeData).Data
1459
1460         var dataOffset int64
1461         var frd FileResumeData
1462         if resumeData != nil {
1463                 if err := frd.UnmarshalBinary(t.GetField(FieldFileResumeData).Data); err != nil {
1464                         return res, err
1465                 }
1466                 // TODO: handle rsrc fork offset
1467                 dataOffset = int64(binary.BigEndian.Uint32(frd.ForkInfoList[0].DataSize[:]))
1468         }
1469
1470         fullFilePath, err := readPath(cc.Server.Config.FileRoot, filePath, fileName)
1471         if err != nil {
1472                 return res, err
1473         }
1474
1475         hlFile, err := newFileWrapper(cc.Server.FS, fullFilePath, dataOffset)
1476         if err != nil {
1477                 return res, err
1478         }
1479
1480         xferSize := hlFile.ffo.TransferSize(0)
1481
1482         ft := cc.newFileTransfer(FileDownload, fileName, filePath, xferSize)
1483
1484         // TODO: refactor to remove this
1485         if resumeData != nil {
1486                 var frd FileResumeData
1487                 if err := frd.UnmarshalBinary(t.GetField(FieldFileResumeData).Data); err != nil {
1488                         return res, err
1489                 }
1490                 ft.fileResumeData = &frd
1491         }
1492
1493         // Optional field for when a HL v1.5+ client requests file preview
1494         // Used only for TEXT, JPEG, GIFF, BMP or PICT files
1495         // The value will always be 2
1496         if t.GetField(FieldFileTransferOptions).Data != nil {
1497                 ft.options = t.GetField(FieldFileTransferOptions).Data
1498                 xferSize = hlFile.ffo.FlatFileDataForkHeader.DataSize[:]
1499         }
1500
1501         res = append(res, cc.NewReply(t,
1502                 NewField(FieldRefNum, ft.refNum[:]),
1503                 NewField(FieldWaitingCount, []byte{0x00, 0x00}), // TODO: Implement waiting count
1504                 NewField(FieldTransferSize, xferSize),
1505                 NewField(FieldFileSize, hlFile.ffo.FlatFileDataForkHeader.DataSize[:]),
1506         ))
1507
1508         return res, err
1509 }
1510
1511 // Download all files from the specified folder and sub-folders
1512 func HandleDownloadFolder(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1513         if !cc.Authorize(accessDownloadFile) {
1514                 res = append(res, cc.NewErrReply(t, "You are not allowed to download folders."))
1515                 return res, err
1516         }
1517
1518         fullFilePath, err := readPath(cc.Server.Config.FileRoot, t.GetField(FieldFilePath).Data, t.GetField(FieldFileName).Data)
1519         if err != nil {
1520                 return res, err
1521         }
1522
1523         transferSize, err := CalcTotalSize(fullFilePath)
1524         if err != nil {
1525                 return res, err
1526         }
1527         itemCount, err := CalcItemCount(fullFilePath)
1528         if err != nil {
1529                 return res, err
1530         }
1531
1532         fileTransfer := cc.newFileTransfer(FolderDownload, t.GetField(FieldFileName).Data, t.GetField(FieldFilePath).Data, transferSize)
1533
1534         var fp FilePath
1535         _, err = fp.Write(t.GetField(FieldFilePath).Data)
1536         if err != nil {
1537                 return res, err
1538         }
1539
1540         res = append(res, cc.NewReply(t,
1541                 NewField(FieldRefNum, fileTransfer.ReferenceNumber),
1542                 NewField(FieldTransferSize, transferSize),
1543                 NewField(FieldFolderItemCount, itemCount),
1544                 NewField(FieldWaitingCount, []byte{0x00, 0x00}), // TODO: Implement waiting count
1545         ))
1546         return res, err
1547 }
1548
1549 // Upload all files from the local folder and its subfolders to the specified path on the server
1550 // Fields used in the request
1551 // 201  File name
1552 // 202  File path
1553 // 108  transfer size   Total size of all items in the folder
1554 // 220  Folder item count
1555 // 204  File transfer options   "Optional Currently set to 1" (TODO: ??)
1556 func HandleUploadFolder(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1557         var fp FilePath
1558         if t.GetField(FieldFilePath).Data != nil {
1559                 if _, err = fp.Write(t.GetField(FieldFilePath).Data); err != nil {
1560                         return res, err
1561                 }
1562         }
1563
1564         // Handle special cases for Upload and Drop Box folders
1565         if !cc.Authorize(accessUploadAnywhere) {
1566                 if !fp.IsUploadDir() && !fp.IsDropbox() {
1567                         res = append(res, cc.NewErrReply(t, fmt.Sprintf("Cannot accept upload of the folder \"%v\" because you are only allowed to upload to the \"Uploads\" folder.", string(t.GetField(FieldFileName).Data))))
1568                         return res, err
1569                 }
1570         }
1571
1572         fileTransfer := cc.newFileTransfer(FolderUpload,
1573                 t.GetField(FieldFileName).Data,
1574                 t.GetField(FieldFilePath).Data,
1575                 t.GetField(FieldTransferSize).Data,
1576         )
1577
1578         fileTransfer.FolderItemCount = t.GetField(FieldFolderItemCount).Data
1579
1580         res = append(res, cc.NewReply(t, NewField(FieldRefNum, fileTransfer.ReferenceNumber)))
1581         return res, err
1582 }
1583
1584 // HandleUploadFile
1585 // Fields used in the request:
1586 // 201  File name
1587 // 202  File path
1588 // 204  File transfer options   "Optional
1589 // Used only to resume download, currently has value 2"
1590 // 108  File transfer size      "Optional used if download is not resumed"
1591 func HandleUploadFile(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1592         if !cc.Authorize(accessUploadFile) {
1593                 res = append(res, cc.NewErrReply(t, "You are not allowed to upload files."))
1594                 return res, err
1595         }
1596
1597         fileName := t.GetField(FieldFileName).Data
1598         filePath := t.GetField(FieldFilePath).Data
1599         transferOptions := t.GetField(FieldFileTransferOptions).Data
1600         transferSize := t.GetField(FieldTransferSize).Data // not sent for resume
1601
1602         var fp FilePath
1603         if filePath != nil {
1604                 if _, err = fp.Write(filePath); err != nil {
1605                         return res, err
1606                 }
1607         }
1608
1609         // Handle special cases for Upload and Drop Box folders
1610         if !cc.Authorize(accessUploadAnywhere) {
1611                 if !fp.IsUploadDir() && !fp.IsDropbox() {
1612                         res = append(res, cc.NewErrReply(t, fmt.Sprintf("Cannot accept upload of the file \"%v\" because you are only allowed to upload to the \"Uploads\" folder.", string(fileName))))
1613                         return res, err
1614                 }
1615         }
1616         fullFilePath, err := readPath(cc.Server.Config.FileRoot, filePath, fileName)
1617         if err != nil {
1618                 return res, err
1619         }
1620
1621         if _, err := cc.Server.FS.Stat(fullFilePath); err == nil {
1622                 res = append(res, cc.NewErrReply(t, fmt.Sprintf("Cannot accept upload because there is already a file named \"%v\".  Try choosing a different name.", string(fileName))))
1623                 return res, err
1624         }
1625
1626         ft := cc.newFileTransfer(FileUpload, fileName, filePath, transferSize)
1627
1628         replyT := cc.NewReply(t, NewField(FieldRefNum, ft.ReferenceNumber))
1629
1630         // client has requested to resume a partially transferred file
1631         if transferOptions != nil {
1632                 fileInfo, err := cc.Server.FS.Stat(fullFilePath + incompleteFileSuffix)
1633                 if err != nil {
1634                         return res, err
1635                 }
1636
1637                 offset := make([]byte, 4)
1638                 binary.BigEndian.PutUint32(offset, uint32(fileInfo.Size()))
1639
1640                 fileResumeData := NewFileResumeData([]ForkInfoList{
1641                         *NewForkInfoList(offset),
1642                 })
1643
1644                 b, _ := fileResumeData.BinaryMarshal()
1645
1646                 ft.TransferSize = offset
1647
1648                 replyT.Fields = append(replyT.Fields, NewField(FieldFileResumeData, b))
1649         }
1650
1651         res = append(res, replyT)
1652         return res, err
1653 }
1654
1655 func HandleSetClientUserInfo(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1656         if len(t.GetField(FieldUserIconID).Data) == 4 {
1657                 cc.Icon = t.GetField(FieldUserIconID).Data[2:]
1658         } else {
1659                 cc.Icon = t.GetField(FieldUserIconID).Data
1660         }
1661         if cc.Authorize(accessAnyName) {
1662                 cc.UserName = t.GetField(FieldUserName).Data
1663         }
1664
1665         // the options field is only passed by the client versions > 1.2.3.
1666         options := t.GetField(FieldOptions).Data
1667         if options != nil {
1668                 optBitmap := big.NewInt(int64(binary.BigEndian.Uint16(options)))
1669                 flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(cc.Flags)))
1670
1671                 flagBitmap.SetBit(flagBitmap, UserFlagRefusePM, optBitmap.Bit(refusePM))
1672                 binary.BigEndian.PutUint16(cc.Flags, uint16(flagBitmap.Int64()))
1673
1674                 flagBitmap.SetBit(flagBitmap, UserFlagRefusePChat, optBitmap.Bit(refuseChat))
1675                 binary.BigEndian.PutUint16(cc.Flags, uint16(flagBitmap.Int64()))
1676
1677                 // Check auto response
1678                 if optBitmap.Bit(autoResponse) == 1 {
1679                         cc.AutoReply = t.GetField(FieldAutomaticResponse).Data
1680                 } else {
1681                         cc.AutoReply = []byte{}
1682                 }
1683         }
1684
1685         for _, c := range sortedClients(cc.Server.Clients) {
1686                 res = append(res, *NewTransaction(
1687                         TranNotifyChangeUser,
1688                         c.ID,
1689                         NewField(FieldUserID, *cc.ID),
1690                         NewField(FieldUserIconID, cc.Icon),
1691                         NewField(FieldUserFlags, cc.Flags),
1692                         NewField(FieldUserName, cc.UserName),
1693                 ))
1694         }
1695
1696         return res, err
1697 }
1698
1699 // HandleKeepAlive responds to keepalive transactions with an empty reply
1700 // * HL 1.9.2 Client sends keepalive msg every 3 minutes
1701 // * HL 1.2.3 Client doesn't send keepalives
1702 func HandleKeepAlive(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1703         res = append(res, cc.NewReply(t))
1704
1705         return res, err
1706 }
1707
1708 func HandleGetFileNameList(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1709         fullPath, err := readPath(
1710                 cc.Server.Config.FileRoot,
1711                 t.GetField(FieldFilePath).Data,
1712                 nil,
1713         )
1714         if err != nil {
1715                 return res, err
1716         }
1717
1718         var fp FilePath
1719         if t.GetField(FieldFilePath).Data != nil {
1720                 if _, err = fp.Write(t.GetField(FieldFilePath).Data); err != nil {
1721                         return res, err
1722                 }
1723         }
1724
1725         // Handle special case for drop box folders
1726         if fp.IsDropbox() && !cc.Authorize(accessViewDropBoxes) {
1727                 res = append(res, cc.NewErrReply(t, "You are not allowed to view drop boxes."))
1728                 return res, err
1729         }
1730
1731         fileNames, err := getFileNameList(fullPath, cc.Server.Config.IgnoreFiles)
1732         if err != nil {
1733                 return res, err
1734         }
1735
1736         res = append(res, cc.NewReply(t, fileNames...))
1737
1738         return res, err
1739 }
1740
1741 // =================================
1742 //     Hotline private chat flow
1743 // =================================
1744 // 1. ClientA sends TranInviteNewChat to server with user ID to invite
1745 // 2. Server creates new ChatID
1746 // 3. Server sends TranInviteToChat to invitee
1747 // 4. Server replies to ClientA with new Chat ID
1748 //
1749 // A dialog box pops up in the invitee client with options to accept or decline the invitation.
1750 // If Accepted is clicked:
1751 // 1. ClientB sends TranJoinChat with FieldChatID
1752
1753 // HandleInviteNewChat invites users to new private chat
1754 func HandleInviteNewChat(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1755         if !cc.Authorize(accessOpenChat) {
1756                 res = append(res, cc.NewErrReply(t, "You are not allowed to request private chat."))
1757                 return res, err
1758         }
1759
1760         // Client to Invite
1761         targetID := t.GetField(FieldUserID).Data
1762         newChatID := cc.Server.NewPrivateChat(cc)
1763
1764         // Check if target user has "Refuse private chat" flag
1765         binary.BigEndian.Uint16(targetID)
1766         targetClient := cc.Server.Clients[binary.BigEndian.Uint16(targetID)]
1767
1768         flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(targetClient.Flags)))
1769         if flagBitmap.Bit(UserFlagRefusePChat) == 1 {
1770                 res = append(res,
1771                         *NewTransaction(
1772                                 TranServerMsg,
1773                                 cc.ID,
1774                                 NewField(FieldData, []byte(string(targetClient.UserName)+" does not accept private chats.")),
1775                                 NewField(FieldUserName, targetClient.UserName),
1776                                 NewField(FieldUserID, *targetClient.ID),
1777                                 NewField(FieldOptions, []byte{0, 2}),
1778                         ),
1779                 )
1780         } else {
1781                 res = append(res,
1782                         *NewTransaction(
1783                                 TranInviteToChat,
1784                                 &targetID,
1785                                 NewField(FieldChatID, newChatID),
1786                                 NewField(FieldUserName, cc.UserName),
1787                                 NewField(FieldUserID, *cc.ID),
1788                         ),
1789                 )
1790         }
1791
1792         res = append(res,
1793                 cc.NewReply(t,
1794                         NewField(FieldChatID, newChatID),
1795                         NewField(FieldUserName, cc.UserName),
1796                         NewField(FieldUserID, *cc.ID),
1797                         NewField(FieldUserIconID, cc.Icon),
1798                         NewField(FieldUserFlags, cc.Flags),
1799                 ),
1800         )
1801
1802         return res, err
1803 }
1804
1805 func HandleInviteToChat(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1806         if !cc.Authorize(accessOpenChat) {
1807                 res = append(res, cc.NewErrReply(t, "You are not allowed to request private chat."))
1808                 return res, err
1809         }
1810
1811         // Client to Invite
1812         targetID := t.GetField(FieldUserID).Data
1813         chatID := t.GetField(FieldChatID).Data
1814
1815         res = append(res,
1816                 *NewTransaction(
1817                         TranInviteToChat,
1818                         &targetID,
1819                         NewField(FieldChatID, chatID),
1820                         NewField(FieldUserName, cc.UserName),
1821                         NewField(FieldUserID, *cc.ID),
1822                 ),
1823         )
1824         res = append(res,
1825                 cc.NewReply(
1826                         t,
1827                         NewField(FieldChatID, chatID),
1828                         NewField(FieldUserName, cc.UserName),
1829                         NewField(FieldUserID, *cc.ID),
1830                         NewField(FieldUserIconID, cc.Icon),
1831                         NewField(FieldUserFlags, cc.Flags),
1832                 ),
1833         )
1834
1835         return res, err
1836 }
1837
1838 func HandleRejectChatInvite(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1839         chatID := t.GetField(FieldChatID).Data
1840         chatInt := binary.BigEndian.Uint32(chatID)
1841
1842         privChat := cc.Server.PrivateChats[chatInt]
1843
1844         resMsg := append(cc.UserName, []byte(" declined invitation to chat")...)
1845
1846         for _, c := range sortedClients(privChat.ClientConn) {
1847                 res = append(res,
1848                         *NewTransaction(
1849                                 TranChatMsg,
1850                                 c.ID,
1851                                 NewField(FieldChatID, chatID),
1852                                 NewField(FieldData, resMsg),
1853                         ),
1854                 )
1855         }
1856
1857         return res, err
1858 }
1859
1860 // HandleJoinChat is sent from a v1.8+ Hotline client when the joins a private chat
1861 // Fields used in the reply:
1862 // * 115        Chat subject
1863 // * 300        User name with info (Optional)
1864 // * 300        (more user names with info)
1865 func HandleJoinChat(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1866         chatID := t.GetField(FieldChatID).Data
1867         chatInt := binary.BigEndian.Uint32(chatID)
1868
1869         privChat := cc.Server.PrivateChats[chatInt]
1870
1871         // Send TranNotifyChatChangeUser to current members of the chat to inform of new user
1872         for _, c := range sortedClients(privChat.ClientConn) {
1873                 res = append(res,
1874                         *NewTransaction(
1875                                 TranNotifyChatChangeUser,
1876                                 c.ID,
1877                                 NewField(FieldChatID, chatID),
1878                                 NewField(FieldUserName, cc.UserName),
1879                                 NewField(FieldUserID, *cc.ID),
1880                                 NewField(FieldUserIconID, cc.Icon),
1881                                 NewField(FieldUserFlags, cc.Flags),
1882                         ),
1883                 )
1884         }
1885
1886         privChat.ClientConn[cc.uint16ID()] = cc
1887
1888         replyFields := []Field{NewField(FieldChatSubject, []byte(privChat.Subject))}
1889         for _, c := range sortedClients(privChat.ClientConn) {
1890                 user := User{
1891                         ID:    *c.ID,
1892                         Icon:  c.Icon,
1893                         Flags: c.Flags,
1894                         Name:  string(c.UserName),
1895                 }
1896
1897                 replyFields = append(replyFields, NewField(FieldUsernameWithInfo, user.Payload()))
1898         }
1899
1900         res = append(res, cc.NewReply(t, replyFields...))
1901         return res, err
1902 }
1903
1904 // HandleLeaveChat is sent from a v1.8+ Hotline client when the user exits a private chat
1905 // Fields used in the request:
1906 //   - 114      FieldChatID
1907 //
1908 // Reply is not expected.
1909 func HandleLeaveChat(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1910         chatID := t.GetField(FieldChatID).Data
1911         chatInt := binary.BigEndian.Uint32(chatID)
1912
1913         privChat, ok := cc.Server.PrivateChats[chatInt]
1914         if !ok {
1915                 return res, nil
1916         }
1917
1918         delete(privChat.ClientConn, cc.uint16ID())
1919
1920         // Notify members of the private chat that the user has left
1921         for _, c := range sortedClients(privChat.ClientConn) {
1922                 res = append(res,
1923                         *NewTransaction(
1924                                 TranNotifyChatDeleteUser,
1925                                 c.ID,
1926                                 NewField(FieldChatID, chatID),
1927                                 NewField(FieldUserID, *cc.ID),
1928                         ),
1929                 )
1930         }
1931
1932         return res, err
1933 }
1934
1935 // HandleSetChatSubject is sent from a v1.8+ Hotline client when the user sets a private chat subject
1936 // Fields used in the request:
1937 // * 114        Chat ID
1938 // * 115        Chat subject
1939 // Reply is not expected.
1940 func HandleSetChatSubject(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1941         chatID := t.GetField(FieldChatID).Data
1942         chatInt := binary.BigEndian.Uint32(chatID)
1943
1944         privChat := cc.Server.PrivateChats[chatInt]
1945         privChat.Subject = string(t.GetField(FieldChatSubject).Data)
1946
1947         for _, c := range sortedClients(privChat.ClientConn) {
1948                 res = append(res,
1949                         *NewTransaction(
1950                                 TranNotifyChatSubject,
1951                                 c.ID,
1952                                 NewField(FieldChatID, chatID),
1953                                 NewField(FieldChatSubject, t.GetField(FieldChatSubject).Data),
1954                         ),
1955                 )
1956         }
1957
1958         return res, err
1959 }
1960
1961 // HandleMakeAlias makes a file alias using the specified path.
1962 // Fields used in the request:
1963 // 201  File name
1964 // 202  File path
1965 // 212  File new path   Destination path
1966 //
1967 // Fields used in the reply:
1968 // None
1969 func HandleMakeAlias(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
1970         if !cc.Authorize(accessMakeAlias) {
1971                 res = append(res, cc.NewErrReply(t, "You are not allowed to make aliases."))
1972                 return res, err
1973         }
1974         fileName := t.GetField(FieldFileName).Data
1975         filePath := t.GetField(FieldFilePath).Data
1976         fileNewPath := t.GetField(FieldFileNewPath).Data
1977
1978         fullFilePath, err := readPath(cc.Server.Config.FileRoot, filePath, fileName)
1979         if err != nil {
1980                 return res, err
1981         }
1982
1983         fullNewFilePath, err := readPath(cc.Server.Config.FileRoot, fileNewPath, fileName)
1984         if err != nil {
1985                 return res, err
1986         }
1987
1988         cc.logger.Debugw("Make alias", "src", fullFilePath, "dst", fullNewFilePath)
1989
1990         if err := cc.Server.FS.Symlink(fullFilePath, fullNewFilePath); err != nil {
1991                 res = append(res, cc.NewErrReply(t, "Error creating alias"))
1992                 return res, nil
1993         }
1994
1995         res = append(res, cc.NewReply(t))
1996         return res, err
1997 }
1998
1999 // HandleDownloadBanner handles requests for a new banner from the server
2000 // Fields used in the request:
2001 // None
2002 // Fields used in the reply:
2003 // 107  FieldRefNum                     Used later for transfer
2004 // 108  FieldTransferSize       Size of data to be downloaded
2005 func HandleDownloadBanner(cc *ClientConn, t *Transaction) (res []Transaction, err error) {
2006         fi, err := cc.Server.FS.Stat(filepath.Join(cc.Server.ConfigDir, cc.Server.Config.BannerFile))
2007         if err != nil {
2008                 return res, err
2009         }
2010
2011         ft := cc.newFileTransfer(bannerDownload, []byte{}, []byte{}, make([]byte, 4))
2012
2013         binary.BigEndian.PutUint32(ft.TransferSize, uint32(fi.Size()))
2014
2015         res = append(res, cc.NewReply(t,
2016                 NewField(FieldRefNum, ft.refNum[:]),
2017                 NewField(FieldTransferSize, ft.TransferSize),
2018         ))
2019
2020         return res, err
2021 }