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

   1 package hotline
   2
   3 import (
   4         "encoding/binary"
   5 )
   6
   7 // User flags are stored as a 2 byte bitmap with the following values:
   8 const (
   9         userFlagAway        = 0 // User is away
  10         userFlagAdmin       = 1 // User is admin
  11         userFlagRefusePM    = 2 // User refuses private messages
  12         userFLagRefusePChat = 3 // User refuses private chat
  13 )
  14
  15 type User struct {
  16         ID    []byte // Size 2
  17         Icon  []byte // Size 2
  18         Flags []byte // Size 2
  19         Name  string // Variable length user name
  20 }
  21
  22 func (u User) Payload() []byte {
  23         nameLen := make([]byte, 2)
  24         binary.BigEndian.PutUint16(nameLen, uint16(len(u.Name)))
  25
  26         if len(u.Icon) == 4 {
  27                 u.Icon = u.Icon[2:]
  28         }
  29
  30         if len(u.Flags) == 4 {
  31                 u.Flags = u.Flags[2:]
  32         }
  33
  34         out := append(u.ID[:2], u.Icon[:2]...)
  35         out = append(out, u.Flags[:2]...)
  36         out = append(out, nameLen...)
  37         out = append(out, u.Name...)
  38
  39         return out
  40 }
  41
  42 func ReadUser(b []byte) (*User, error) {
  43         u := &User{
  44                 ID:    b[0:2],
  45                 Icon:  b[2:4],
  46                 Flags: b[4:6],
  47                 Name:  string(b[8:]),
  48         }
  49         return u, nil
  50 }
  51
  52 // DecodeUserString decodes an obfuscated user string from a client
  53 // e.g. 98 8a 9a 8c 8b => "guest"
  54 func DecodeUserString(obfuText []byte) (clearText string) {
  55         for _, char := range obfuText {
  56                 clearText += string(rune(255 - uint(char)))
  57         }
  58         return clearText
  59 }
  60
  61 // negateString takes []byte s containing cleartext and rotates by 255 into obfuscated cleartext.
  62 // The Hotline protocol uses this format for sending passwords over network.
  63 // Not secure, but hey, it was the 90s!
  64 func negateString(clearText []byte) []byte {
  65         obfuText := make([]byte, len(clearText))
  66         for i := 0; i < len(clearText); i++ {
  67                 obfuText[i] = 255 - clearText[i]
  68         }
  69         return obfuText
  70 }