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

   1 package hotline
   2
   3 import (
   4         "encoding/binary"
   5         "io"
   6         "slices"
   7 )
   8
   9 // User flags are stored as a 2 byte bitmap and represent various user states
  10 const (
  11         UserFlagAway        = iota // User is away
  12         UserFlagAdmin              // User is admin
  13         UserFlagRefusePM           // User refuses private messages
  14         UserFlagRefusePChat        // User refuses private chat
  15 )
  16
  17 // FieldOptions flags are sent from v1.5+ clients as part of TranAgreed
  18 const (
  19         UserOptRefusePM     = iota // User has "Refuse private messages" pref set
  20         UserOptRefuseChat          // User has "Refuse private chat" pref set
  21         UserOptAutoResponse        // User has "Automatic response" pref set
  22 )
  23
  24 type User struct {
  25         ID    []byte // Size 2
  26         Icon  []byte // Size 2
  27         Flags []byte // Size 2
  28         Name  string // Variable length user name
  29
  30         readOffset int // Internal offset to track read progress
  31 }
  32
  33 func (u *User) Read(p []byte) (int, error) {
  34         nameLen := make([]byte, 2)
  35         binary.BigEndian.PutUint16(nameLen, uint16(len(u.Name)))
  36
  37         if len(u.Icon) == 4 {
  38                 u.Icon = u.Icon[2:]
  39         }
  40
  41         if len(u.Flags) == 4 {
  42                 u.Flags = u.Flags[2:]
  43         }
  44
  45         b := slices.Concat(
  46                 u.ID,
  47                 u.Icon,
  48                 u.Flags,
  49                 nameLen,
  50                 []byte(u.Name),
  51         )
  52
  53         if u.readOffset >= len(b) {
  54                 return 0, io.EOF // All bytes have been read
  55         }
  56
  57         n := copy(p, b)
  58
  59         return n, io.EOF
  60 }
  61
  62 func (u *User) Write(p []byte) (int, error) {
  63         namelen := int(binary.BigEndian.Uint16(p[6:8]))
  64         u.ID = p[0:2]
  65         u.Icon = p[2:4]
  66         u.Flags = p[4:6]
  67         u.Name = string(p[8 : 8+namelen])
  68
  69         return 8 + namelen, nil
  70 }
  71
  72 // encodeString takes []byte s containing cleartext and rotates by 255 into obfuscated cleartext.
  73 // The Hotline protocol uses this format for sending passwords over network.
  74 // Not secure, but hey, it was the 90s!
  75 func encodeString(clearText []byte) []byte {
  76         obfuText := make([]byte, len(clearText))
  77         for i := 0; i < len(clearText); i++ {
  78                 obfuText[i] = 255 - clearText[i]
  79         }
  80         return obfuText
  81 }