forked from qdeconinck/mp-quic
/
server_config_client.go
180 lines (151 loc) · 4.18 KB
/
server_config_client.go
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package handshake
import (
"bytes"
"encoding/binary"
"errors"
"math"
"time"
"github.com/lucas-clemente/quic-go/internal/crypto"
"github.com/lucas-clemente/quic-go/internal/utils"
"github.com/lucas-clemente/quic-go/qerr"
)
type serverConfigClient struct {
raw []byte
ID []byte
obit []byte
expiry time.Time
kex crypto.KeyExchange
sharedSecret []byte
}
var (
errMessageNotServerConfig = errors.New("ServerConfig must have TagSCFG")
)
// parseServerConfig parses a server config
func parseServerConfig(data []byte) (*serverConfigClient, error) {
message, err := ParseHandshakeMessage(bytes.NewReader(data))
if err != nil {
return nil, err
}
if message.Tag != TagSCFG {
return nil, errMessageNotServerConfig
}
scfg := &serverConfigClient{raw: data}
err = scfg.parseValues(message.Data)
if err != nil {
return nil, err
}
return scfg, nil
}
func (s *serverConfigClient) parseValues(tagMap map[Tag][]byte) error {
// SCID
scfgID, ok := tagMap[TagSCID]
if !ok {
return qerr.Error(qerr.CryptoMessageParameterNotFound, "SCID")
}
if len(scfgID) != 16 {
return qerr.Error(qerr.CryptoInvalidValueLength, "SCID")
}
s.ID = scfgID
// KEXS
// TODO: setup Key Exchange
kexs, ok := tagMap[TagKEXS]
if !ok {
return qerr.Error(qerr.CryptoMessageParameterNotFound, "KEXS")
}
if len(kexs)%4 != 0 {
return qerr.Error(qerr.CryptoInvalidValueLength, "KEXS")
}
c255Foundat := -1
for i := 0; i < len(kexs)/4; i++ {
if bytes.Equal(kexs[4*i:4*i+4], []byte("C255")) {
c255Foundat = i
break
}
}
if c255Foundat < 0 {
return qerr.Error(qerr.CryptoNoSupport, "KEXS: Could not find C255, other key exchanges are not supported")
}
// AEAD
aead, ok := tagMap[TagAEAD]
if !ok {
return qerr.Error(qerr.CryptoMessageParameterNotFound, "AEAD")
}
if len(aead)%4 != 0 {
return qerr.Error(qerr.CryptoInvalidValueLength, "AEAD")
}
var aesgFound bool
for i := 0; i < len(aead)/4; i++ {
if bytes.Equal(aead[4*i:4*i+4], []byte("AESG")) {
aesgFound = true
break
}
}
if !aesgFound {
return qerr.Error(qerr.CryptoNoSupport, "AEAD")
}
// PUBS
pubs, ok := tagMap[TagPUBS]
if !ok {
return qerr.Error(qerr.CryptoMessageParameterNotFound, "PUBS")
}
var pubs_kexs []struct{Length uint32; Value []byte}
var last_len uint32
for i := 0; i < len(pubs)-3; i += int(last_len)+3 {
// the PUBS value is always prepended by 3 byte little endian length field
err := binary.Read(bytes.NewReader([]byte{pubs[i], pubs[i+1], pubs[i+2], 0x00}), binary.LittleEndian, &last_len);
if err != nil {
return qerr.Error(qerr.CryptoInvalidValueLength, "PUBS not decodable")
}
if last_len == 0 {
return qerr.Error(qerr.CryptoInvalidValueLength, "PUBS")
}
if i+3+int(last_len) > len(pubs) {
return qerr.Error(qerr.CryptoInvalidValueLength, "PUBS")
}
pubs_kexs = append(pubs_kexs, struct{Length uint32; Value []byte}{last_len, pubs[i+3:i+3+int(last_len)]})
}
if c255Foundat >= len(pubs_kexs) {
return qerr.Error(qerr.CryptoMessageParameterNotFound, "KEXS not in PUBS")
}
if pubs_kexs[c255Foundat].Length != 32 {
return qerr.Error(qerr.CryptoInvalidValueLength, "PUBS")
}
var err error
s.kex, err = crypto.NewCurve25519KEX()
if err != nil {
return err
}
s.sharedSecret, err = s.kex.CalculateSharedKey(pubs_kexs[c255Foundat].Value)
if err != nil {
return err
}
// OBIT
obit, ok := tagMap[TagOBIT]
if !ok {
return qerr.Error(qerr.CryptoMessageParameterNotFound, "OBIT")
}
if len(obit) != 8 {
return qerr.Error(qerr.CryptoInvalidValueLength, "OBIT")
}
s.obit = obit
// EXPY
expy, ok := tagMap[TagEXPY]
if !ok {
return qerr.Error(qerr.CryptoMessageParameterNotFound, "EXPY")
}
if len(expy) != 8 {
return qerr.Error(qerr.CryptoInvalidValueLength, "EXPY")
}
// make sure that the value doesn't overflow an int64
// furthermore, values close to MaxInt64 are not a valid input to time.Unix, thus set MaxInt64/2 as the maximum value here
expyTimestamp := utils.MinUint64(binary.LittleEndian.Uint64(expy), math.MaxInt64/2)
s.expiry = time.Unix(int64(expyTimestamp), 0)
// TODO: implement VER
return nil
}
func (s *serverConfigClient) IsExpired() bool {
return s.expiry.Before(time.Now())
}
func (s *serverConfigClient) Get() []byte {
return s.raw
}