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Added parsing of PUBS tag and filtering according to KEXS

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This now allows quic-go to contact servers announcing multiple KEXS methods, e.g. like Akamai.
This commit is contained in:
Jan Rüth
2017-05-11 19:54:49 +02:00
parent 6628994883
commit f558bdebed
1 changed files with 30 additions and 6 deletions
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36
handshake/server_config_client.go
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@@ -57,7 +57,6 @@ func (s *serverConfigClient) parseValues(tagMap map[Tag][]byte) error {
s.ID = scfgID
// KEXS
// TODO: allow for P256 in the list
// TODO: setup Key Exchange
kexs, ok := tagMap[TagKEXS]
if !ok {
@@ -66,7 +65,15 @@ func (s *serverConfigClient) parseValues(tagMap map[Tag][]byte) error {
if len(kexs)%4 != 0 {
return qerr.Error(qerr.CryptoInvalidValueLength, "KEXS")
}
if !bytes.Equal(kexs, []byte("C255")) {
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")
}
@@ -90,12 +97,29 @@ func (s *serverConfigClient) parseValues(tagMap map[Tag][]byte) error {
}
// PUBS
// TODO: save this value
pubs, ok := tagMap[TagPUBS]
if !ok {
return qerr.Error(qerr.CryptoMessageParameterNotFound, "PUBS")
}
if len(pubs) != 35 {
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")
}
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.CryptoInvalidValueLength, "KEXS not in PUBS")
}
if pubs_kexs[c255Foundat].Length != 32 {
return qerr.Error(qerr.CryptoInvalidValueLength, "PUBS")
}
@@ -105,8 +129,8 @@ func (s *serverConfigClient) parseValues(tagMap map[Tag][]byte) error {
return err
}
// the PUBS value is always prepended by []byte{0x20, 0x00, 0x00}
s.sharedSecret, err = s.kex.CalculateSharedKey(pubs[3:])
s.sharedSecret, err = s.kex.CalculateSharedKey(pubs_kexs[c255Foundat].Value)
if err != nil {
return err
}