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check clock skew and terminate

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orignal 2022-07-13 12:45:20 -04:00
parent 90981f628e
commit 5c62726992
2 changed files with 18 additions and 2 deletions
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18
libi2pd/SSU2Session.cpp
View file

@ -497,6 +497,7 @@ namespace transport
}
m_NoiseState->MixHash (payload, len - 64); // h = SHA256(h || encrypted payload from Session Request) for SessionCreated
// payload
m_State = eSSU2SessionStateSessionRequestReceived;
HandlePayload (decryptedPayload.data (), decryptedPayload.size ());
m_Server.AddSession (shared_from_this ());
@ -527,11 +528,12 @@ namespace transport
memset (headerX + 8, 0, 8); // token = 0
memcpy (headerX + 16, m_EphemeralKeys->GetPublicKey (), 32); // Y
// payload
const size_t maxPayloadSize = SSU2_MAX_PAYLOAD_SIZE - 48;
payload[0] = eSSU2BlkDateTime;
htobe16buf (payload + 1, 4);
htobe32buf (payload + 3, ts);
size_t payloadSize = 7;
payloadSize += CreateAddressBlock (payload + payloadSize, 80 - payloadSize, m_RemoteEndpoint);
payloadSize += CreateAddressBlock (payload + payloadSize, maxPayloadSize - payloadSize, m_RemoteEndpoint);
if (m_RelayTag)
{
payload[payloadSize] = eSSU2BlkRelayTag;
@ -548,7 +550,9 @@ namespace transport
memcpy (payload + payloadSize + 7, &token.first, 8); // token
payloadSize += 15;
}
payloadSize += CreatePaddingBlock (payload + payloadSize, 80 - payloadSize);
if (m_TerminationReason != eSSU2TerminationReasonNormalClose)
payloadSize += CreateTerminationBlock (payload + payloadSize, maxPayloadSize - payloadSize);
payloadSize += CreatePaddingBlock (payload + payloadSize, maxPayloadSize - payloadSize);
// KDF for SessionCreated
m_NoiseState->MixHash ( { {header.buf, 16}, {headerX, 16} } ); // h = SHA256(h || header)
m_NoiseState->MixHash (headerX + 16, 32); // h = SHA256(h || bepk);
@ -567,6 +571,9 @@ namespace transport
m_SentHandshakePacket->payloadSize = payloadSize;
// send
m_Server.Send (header.buf, 16, headerX, 48, payload, payloadSize, m_RemoteEndpoint);
// terminate if errors
if (m_TerminationReason != eSSU2TerminationReasonNormalClose)
Terminate ();
}
bool SSU2Session::ProcessSessionCreated (uint8_t * buf, size_t len)
@ -1180,6 +1187,13 @@ namespace transport
{
case eSSU2BlkDateTime:
LogPrint (eLogDebug, "SSU2: Datetime");
if (m_State == eSSU2SessionStateSessionRequestReceived)
{
auto ts = i2p::util::GetSecondsSinceEpoch ();
uint32_t signedOnTime = bufbe32toh (buf + offset);
if (signedOnTime < ts - SSU2_CLOCK_SKEW || signedOnTime > ts + SSU2_CLOCK_SKEW)
m_TerminationReason = eSSU2TerminationReasonClockSkew;
};
break;
case eSSU2BlkOptions:
LogPrint (eLogDebug, "SSU2: Options");

2
libi2pd/SSU2Session.h
View file

@ -26,6 +26,7 @@ namespace transport
{
const int SSU2_CONNECT_TIMEOUT = 5; // 5 seconds
const int SSU2_TERMINATION_TIMEOUT = 330; // 5.5 minutes
const int SSU2_CLOCK_SKEW = 60; // in seconds
const int SSU2_TOKEN_EXPIRATION_TIMEOUT = 9; // for Retry message, in seconds
const int SSU2_NEXT_TOKEN_EXPIRATION_TIMEOUT = 52*60; // for next token block, in seconds
const int SSU2_TOKEN_EXPIRATION_THRESHOLD = 2; // in seconds
@ -84,6 +85,7 @@ namespace transport
eSSU2SessionStateUnknown,
eSSU2SessionStateTokenReceived,
eSSU2SessionStateSessionRequestSent,
eSSU2SessionStateSessionRequestReceived,
eSSU2SessionStateSessionCreatedSent,
eSSU2SessionStateSessionConfirmedSent,
eSSU2SessionStateEstablished,