// Reset generates a new distribution with the same min/max based on a new
// seed.
func (w *WeightedDist) Reset(seed *drbg.Seed) {
// Initialize the deterministic random number generator.
drbg, _ := drbg.NewHashDrbg(seed)
rng := rand.New(drbg)
w.Lock()
defer w.Unlock()
w.genValues(rng)
if w.biased {
w.genBiasedWeights(rng)
} else {
w.genUniformWeights(rng)
}
w.genTables()
}
// NewDecoder creates a new Decoder instance. It must be supplied a slice
// containing exactly KeyLength bytes of keying material.
func NewDecoder(key []byte) *Decoder {
if len(key) != KeyLength {
panic(fmt.Sprintf("BUG: Invalid decoder key length: %d", len(key)))
}
decoder := new(Decoder)
copy(decoder.key[:], key[0:keyLength])
decoder.nonce.init(key[keyLength : keyLength+noncePrefixLength])
seed, err := drbg.SeedFromBytes(key[keyLength+noncePrefixLength:])
if err != nil {
panic(fmt.Sprintf("BUG: Failed to initialize DRBG: %s", err))
}
decoder.drbg, _ = drbg.NewHashDrbg(seed)
return decoder
}
// ServerFactory returns a new obfs4ServerFactory instance.
func (t *Transport) ServerFactory(stateDir string, args *pt.Args) (base.ServerFactory, error) {
st, err := serverStateFromArgs(stateDir, args)
if err != nil {
return nil, err
}
var iatSeed *drbg.Seed
if st.iatMode != iatNone {
iatSeedSrc := sha256.Sum256(st.drbgSeed.Bytes()[:])
var err error
iatSeed, err = drbg.SeedFromBytes(iatSeedSrc[:])
if err != nil {
return nil, err
}
}
// Store the arguments that should appear in our descriptor for the clients.
ptArgs := pt.Args{}
ptArgs.Add(certArg, st.cert.String())
ptArgs.Add(iatArg, strconv.Itoa(st.iatMode))
// Initialize the replay filter.
filter, err := replayfilter.New(replayTTL)
if err != nil {
return nil, err
}
// Initialize the close thresholds for failed connections.
drbg, err := drbg.NewHashDrbg(st.drbgSeed)
if err != nil {
return nil, err
}
rng := rand.New(drbg)
sf := &obfs4ServerFactory{t, &ptArgs, st.nodeID, st.identityKey, st.drbgSeed, iatSeed, st.iatMode, filter, rng.Intn(maxCloseDelayBytes), rng.Intn(maxCloseDelay)}
return sf, nil
}