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avoid replay upon SSU packet resend

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orignal 2020-08-08 19:01:55 -04:00
parent 8e25226574
commit e50abbb250
3 changed files with 32 additions and 18 deletions
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26
libi2pd/SSUSession.cpp
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@ -744,27 +744,33 @@ namespace transport
}
void SSUSession::FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len)
{
FillHeaderAndEncrypt (payloadType, buf, len, buf);
}
void SSUSession::FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * in, size_t len, uint8_t * out)
{
if (len < sizeof (SSUHeader))
{
LogPrint (eLogError, "SSU: Unexpected packet length ", len);
return;
}
SSUHeader * header = (SSUHeader *)buf;
SSUHeader * header = (SSUHeader *)out;
RAND_bytes (header->iv, 16); // random iv
m_SessionKeyEncryption.SetIV (header->iv);
header->flag = payloadType << 4; // MSB is 0
htobe32buf (header->time, i2p::util::GetSecondsSinceEpoch ());
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
m_SessionKeyEncryption.Encrypt (encrypted, encryptedLen, encrypted);
// assume actual buffer size is 18 (16 + 2) bytes more
memcpy (buf + len, header->iv, 16);
SSUHeader * inHeader = (SSUHeader *)in;
inHeader->flag = payloadType << 4; // MSB is 0
htobe32buf (inHeader->time, i2p::util::GetSecondsSinceEpoch ());
uint8_t * encrypted = &header->flag, * clear = &inHeader->flag;
uint16_t encryptedLen = len - (encrypted - out);
m_SessionKeyEncryption.Encrypt (clear, encryptedLen, encrypted);
// assume actual out buffer size is 18 (16 + 2) bytes more
memcpy (out + len, header->iv, 16);
uint16_t netid = i2p::context.GetNetID ();
htobe16buf (buf + len + 16, (netid == I2PD_NET_ID) ? encryptedLen : encryptedLen ^ ((netid - 2) << 8));
htobe16buf (out + len + 16, (netid == I2PD_NET_ID) ? encryptedLen : encryptedLen ^ ((netid - 2) << 8));
i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, m_MacKey, header->mac);
}
void SSUSession::Decrypt (uint8_t * buf, size_t len, const i2p::crypto::AESKey& aesKey)
{
if (len < sizeof (SSUHeader))