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package hotline
import (
"encoding/binary"
"io"
"math/big"
"slices"
)
// User flags are stored as a 2 byte bitmap and represent various user states
const (
UserFlagAway = 0 // User is away
UserFlagAdmin = 1 // User is admin
UserFlagRefusePM = 2 // User refuses private messages
UserFlagRefusePChat = 3 // User refuses private chat
)
// User options are sent from clients and represent options set in the client's preferences.
const (
UserOptRefusePM = 0 // User has "Refuse private messages" pref set
UserOptRefuseChat = 1 // User has "Refuse private chat" pref set
UserOptAutoResponse = 2 // User has "Automatic response" pref set
)
type UserFlags [2]byte
func (f *UserFlags) IsSet(i int) bool {
flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(f[:])))
return flagBitmap.Bit(i) == 1
}
func (f *UserFlags) Set(i int, newVal uint) {
flagBitmap := big.NewInt(int64(binary.BigEndian.Uint16(f[:])))
flagBitmap.SetBit(flagBitmap, i, newVal)
binary.BigEndian.PutUint16(f[:], uint16(flagBitmap.Int64()))
}
type User struct {
ID [2]byte
Icon []byte // Size 2
Flags []byte // Size 2
Name string // Variable length user name
readOffset int // Internal offset to track read progress
}
func (u *User) Read(p []byte) (int, error) {
nameLen := make([]byte, 2)
binary.BigEndian.PutUint16(nameLen, uint16(len(u.Name)))
if len(u.Icon) == 4 {
u.Icon = u.Icon[2:]
}
if len(u.Flags) == 4 {
u.Flags = u.Flags[2:]
}
b := slices.Concat(
u.ID[:],
u.Icon,
u.Flags,
nameLen,
[]byte(u.Name),
)
if u.readOffset >= len(b) {
return 0, io.EOF // All bytes have been read
}
n := copy(p, b)
u.readOffset = n
return n, nil
}
func (u *User) Write(p []byte) (int, error) {
namelen := int(binary.BigEndian.Uint16(p[6:8]))
u.ID = [2]byte(p[0:2])
u.Icon = p[2:4]
u.Flags = p[4:6]
u.Name = string(p[8 : 8+namelen])
return 8 + namelen, nil
}
// EncodeString takes []byte s containing cleartext and rotates by 255 into obfuscated cleartext.
// The Hotline protocol uses this format for sending passwords over network.
// Not secure, but hey, it was the 90s!
func EncodeString(clearText []byte) []byte {
obfuText := make([]byte, len(clearText))
for i := 0; i < len(clearText); i++ {
obfuText[i] = 255 - clearText[i]
}
return obfuText
}
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