wireguard-go-awg2-lx/device/obf_randchars.go
Leadaxe ee7ff1b77f lx: fix transport padding buffer overrun + harden AWG config guards
Transport padding (s4) crashed the whole process with
"index out of range" in RoutineSequentialSender on the first data
packet: InputPacket/InputPackets sized elem.buffer without headroom
for the in-buffer right-shift that prepends the random prefix.

- send.go: reserve paddings.transport in both injection-path
  allocLength computations; replace the manual backward byte loop
  with an overlap-safe copy; defensively grow the buffer (pool-backed)
  if it still lacks headroom, dropping packets that cannot fit a
  single WG message instead of overrunning.
- receive.go: drop the rxBytes/timers block duplicated by the AWG
  re-graft (rx accounting was doubled, keepKeyFreshReceiving fired
  twice per batch).
- send.go: swap jmin/jmax when configured inverted (UAPI validates
  the fields only individually; a swapped pair panicked rand.Int
  with a non-positive bound on the first handshake).
- obf*.go: bound obfuscator length args to [0, MaxMessageSize]
  (negative panicked slice bounds, huge ones OOMed the handshake).
- magic-header.go: widen to int64 before end-start+1 so a full-range
  header cannot wrap to a zero rand.Int bound.

Tests: transport_padding_test.go reproduces the on-device crash
byte-for-byte (red on the previous commit, green now) across both
injection paths and the tun path; obf_guards_test.go pins the
config-value guards.
2026-08-05 16:55:02 +03:00

47 lines
783 B
Go

package device
import (
"crypto/rand"
"unicode"
)
const chars52 = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
func newRandCharObf(val string) (obf, error) {
length, err := parseObfLen(val)
if err != nil {
return nil, err
}
return &randCharObf{
length: length,
}, nil
}
type randCharObf struct {
length int
}
func (o *randCharObf) Obfuscate(dst, src []byte) {
rand.Read(dst[:o.length])
for i := range dst[:o.length] {
dst[i] = chars52[dst[i]%52]
}
}
func (o *randCharObf) Deobfuscate(dst, src []byte) bool {
for _, b := range src[:o.length] {
if !unicode.IsLetter(rune(b)) {
return false
}
}
return true
}
func (o *randCharObf) ObfuscatedLen(n int) int {
return o.length
}
func (o *randCharObf) DeobfuscatedLen(n int) int {
return 0
}