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

   1 package hotline
   2
   3 import (
   4         "bufio"
   5         "bytes"
   6         "encoding/binary"
   7         "errors"
   8         "fmt"
   9         "io"
  10         "math/rand"
  11         "slices"
  12 )
  13
  14 const (
  15         TranError                = 0
  16         TranGetMsgs              = 101
  17         TranNewMsg               = 102
  18         TranOldPostNews          = 103
  19         TranServerMsg            = 104
  20         TranChatSend             = 105
  21         TranChatMsg              = 106
  22         TranLogin                = 107
  23         TranSendInstantMsg       = 108
  24         TranShowAgreement        = 109
  25         TranDisconnectUser       = 110
  26         TranDisconnectMsg        = 111 // TODO: implement server initiated friendly disconnect
  27         TranInviteNewChat        = 112
  28         TranInviteToChat         = 113
  29         TranRejectChatInvite     = 114
  30         TranJoinChat             = 115
  31         TranLeaveChat            = 116
  32         TranNotifyChatChangeUser = 117
  33         TranNotifyChatDeleteUser = 118
  34         TranNotifyChatSubject    = 119
  35         TranSetChatSubject       = 120
  36         TranAgreed               = 121
  37         TranServerBanner         = 122
  38         TranGetFileNameList      = 200
  39         TranDownloadFile         = 202
  40         TranUploadFile           = 203
  41         TranNewFolder            = 205
  42         TranDeleteFile           = 204
  43         TranGetFileInfo          = 206
  44         TranSetFileInfo          = 207
  45         TranMoveFile             = 208
  46         TranMakeFileAlias        = 209
  47         TranDownloadFldr         = 210
  48         TranDownloadInfo         = 211 // TODO: implement file transfer queue
  49         TranDownloadBanner       = 212
  50         TranUploadFldr           = 213
  51         TranGetUserNameList      = 300
  52         TranNotifyChangeUser     = 301
  53         TranNotifyDeleteUser     = 302
  54         TranGetClientInfoText    = 303
  55         TranSetClientUserInfo    = 304
  56         TranListUsers            = 348
  57         TranUpdateUser           = 349
  58         TranNewUser              = 350
  59         TranDeleteUser           = 351
  60         TranGetUser              = 352
  61         TranSetUser              = 353
  62         TranUserAccess           = 354
  63         TranUserBroadcast        = 355
  64         TranGetNewsCatNameList   = 370
  65         TranGetNewsArtNameList   = 371
  66         TranDelNewsItem          = 380
  67         TranNewNewsFldr          = 381
  68         TranNewNewsCat           = 382
  69         TranGetNewsArtData       = 400
  70         TranPostNewsArt          = 410
  71         TranDelNewsArt           = 411
  72         TranKeepAlive            = 500
  73 )
  74
  75 type Transaction struct {
  76         Flags      byte   // Reserved (should be 0)
  77         IsReply    byte   // Request (0) or reply (1)
  78         Type       []byte // Requested operation (user defined)
  79         ID         []byte // Unique transaction ID (must be != 0)
  80         ErrorCode  []byte // Used in the reply (user defined, 0 = no error)
  81         TotalSize  []byte // Total data size for the transaction (all parts)
  82         DataSize   []byte // Size of data in this transaction part. This allows splitting large transactions into smaller parts.
  83         ParamCount []byte // Number of the parameters for this transaction
  84         Fields     []Field
  85
  86         clientID   *[]byte // Internal identifier for target client
  87         readOffset int     // Internal offset to track read progress
  88 }
  89
  90 func NewTransaction(t int, clientID *[]byte, fields ...Field) *Transaction {
  91         typeSlice := make([]byte, 2)
  92         binary.BigEndian.PutUint16(typeSlice, uint16(t))
  93
  94         idSlice := make([]byte, 4)
  95         binary.BigEndian.PutUint32(idSlice, rand.Uint32())
  96
  97         return &Transaction{
  98                 clientID:  clientID,
  99                 Flags:     0x00,
 100                 IsReply:   0x00,
 101                 Type:      typeSlice,
 102                 ID:        idSlice,
 103                 ErrorCode: []byte{0, 0, 0, 0},
 104                 Fields:    fields,
 105         }
 106 }
 107
 108 // Write implements io.Writer interface for Transaction
 109 func (t *Transaction) Write(p []byte) (n int, err error) {
 110         totalSize := binary.BigEndian.Uint32(p[12:16])
 111
 112         // the buf may include extra bytes that are not part of the transaction
 113         // tranLen represents the length of bytes that are part of the transaction
 114         tranLen := int(20 + totalSize)
 115
 116         if tranLen > len(p) {
 117                 return n, errors.New("buflen too small for tranLen")
 118         }
 119
 120         // Create a new scanner for parsing incoming bytes into transaction tokens
 121         scanner := bufio.NewScanner(bytes.NewReader(p[22:tranLen]))
 122         scanner.Split(fieldScanner)
 123
 124         for i := 0; i < int(binary.BigEndian.Uint16(p[20:22])); i++ {
 125                 scanner.Scan()
 126
 127                 var field Field
 128                 if _, err := field.Write(scanner.Bytes()); err != nil {
 129                         return 0, fmt.Errorf("error reading field: %w", err)
 130                 }
 131                 t.Fields = append(t.Fields, field)
 132         }
 133
 134         t.Flags = p[0]
 135         t.IsReply = p[1]
 136         t.Type = p[2:4]
 137         t.ID = p[4:8]
 138         t.ErrorCode = p[8:12]
 139         t.TotalSize = p[12:16]
 140         t.DataSize = p[16:20]
 141         t.ParamCount = p[20:22]
 142
 143         return len(p), err
 144 }
 145
 146 const tranHeaderLen = 20 // fixed length of transaction fields before the variable length fields
 147
 148 // transactionScanner implements bufio.SplitFunc for parsing incoming byte slices into complete tokens
 149 func transactionScanner(data []byte, _ bool) (advance int, token []byte, err error) {
 150         // The bytes that contain the size of a transaction are from 12:16, so we need at least 16 bytes
 151         if len(data) < 16 {
 152                 return 0, nil, nil
 153         }
 154
 155         totalSize := binary.BigEndian.Uint32(data[12:16])
 156
 157         // tranLen represents the length of bytes that are part of the transaction
 158         tranLen := int(tranHeaderLen + totalSize)
 159         if tranLen > len(data) {
 160                 return 0, nil, nil
 161         }
 162
 163         return tranLen, data[0:tranLen], nil
 164 }
 165
 166 const minFieldLen = 4
 167
 168 func ReadFields(paramCount []byte, buf []byte) ([]Field, error) {
 169         paramCountInt := int(binary.BigEndian.Uint16(paramCount))
 170         if paramCountInt > 0 && len(buf) < minFieldLen {
 171                 return []Field{}, fmt.Errorf("invalid field length %v", len(buf))
 172         }
 173
 174         // A Field consists of:
 175         // ID: 2 bytes
 176         // Size: 2 bytes
 177         // Data: FieldSize number of bytes
 178         var fields []Field
 179         for i := 0; i < paramCountInt; i++ {
 180                 if len(buf) < minFieldLen {
 181                         return []Field{}, fmt.Errorf("invalid field length %v", len(buf))
 182                 }
 183                 fieldID := buf[0:2]
 184                 fieldSize := buf[2:4]
 185                 fieldSizeInt := int(binary.BigEndian.Uint16(buf[2:4]))
 186                 expectedLen := minFieldLen + fieldSizeInt
 187                 if len(buf) < expectedLen {
 188                         return []Field{}, fmt.Errorf("field length too short")
 189                 }
 190
 191                 fields = append(fields, Field{
 192                         ID:        [2]byte(fieldID),
 193                         FieldSize: [2]byte(fieldSize),
 194                         Data:      buf[4 : 4+fieldSizeInt],
 195                 })
 196
 197                 buf = buf[fieldSizeInt+4:]
 198         }
 199
 200         if len(buf) != 0 {
 201                 return []Field{}, fmt.Errorf("extra field bytes")
 202         }
 203
 204         return fields, nil
 205 }
 206
 207 // Read implements the io.Reader interface for Transaction
 208 func (t *Transaction) Read(p []byte) (int, error) {
 209         payloadSize := t.Size()
 210
 211         fieldCount := make([]byte, 2)
 212         binary.BigEndian.PutUint16(fieldCount, uint16(len(t.Fields)))
 213
 214         bbuf := new(bytes.Buffer)
 215
 216         for _, field := range t.Fields {
 217                 f := field
 218                 _, err := bbuf.ReadFrom(&f)
 219                 if err != nil {
 220                         return 0, fmt.Errorf("error reading field: %w", err)
 221                 }
 222         }
 223
 224         buf := slices.Concat(
 225                 []byte{t.Flags, t.IsReply},
 226                 t.Type,
 227                 t.ID,
 228                 t.ErrorCode,
 229                 payloadSize,
 230                 payloadSize, // this is the dataSize field, but seeming the same as totalSize
 231                 fieldCount,
 232                 bbuf.Bytes(),
 233         )
 234
 235         if t.readOffset >= len(buf) {
 236                 return 0, io.EOF // All bytes have been read
 237         }
 238
 239         n := copy(p, buf[t.readOffset:])
 240         t.readOffset += n
 241
 242         return n, nil
 243 }
 244
 245 // Size returns the total size of the transaction payload
 246 func (t *Transaction) Size() []byte {
 247         bs := make([]byte, 4)
 248
 249         fieldSize := 0
 250         for _, field := range t.Fields {
 251                 fieldSize += len(field.Data) + 4
 252         }
 253
 254         binary.BigEndian.PutUint32(bs, uint32(fieldSize+2))
 255
 256         return bs
 257 }
 258
 259 func (t *Transaction) GetField(id int) Field {
 260         for _, field := range t.Fields {
 261                 if id == int(binary.BigEndian.Uint16(field.ID[:])) {
 262                         return field
 263                 }
 264         }
 265
 266         return Field{}
 267 }
 268
 269 func (t *Transaction) IsError() bool {
 270         return bytes.Equal(t.ErrorCode, []byte{0, 0, 0, 1})
 271 }