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Fix client Initial key discard to trigger on any Handshake packet send #5899

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Fix client Initial key discard to trigger on any Handshake packet send #5899

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8fa7f86
Drop initial key state as soon as a handshake packet is sent
guhetier Mar 27, 2026
3d078b6
Always set the offsets when a key was written
guhetier Mar 28, 2026
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10 changes: 0 additions & 10 deletions src/core/crypto.c
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Original file line number Diff line number Diff line change
Expand Up @@ -941,16 +941,6 @@ QuicCryptoWriteFrames(
return TRUE;
}

if (QuicConnIsClient(Connection) &&
Builder->Key == Crypto->TlsState.WriteKeys[QUIC_PACKET_KEY_HANDSHAKE]) {
CXPLAT_DBG_ASSERT(Builder->Key);
//
// Per spec, client MUST discard Initial keys when it starts
// encrypting packets with handshake keys.
//
QuicCryptoDiscardKeys(Crypto, QUIC_PACKET_KEY_INITIAL);
}

uint8_t PrevFrameCount = Builder->Metadata->FrameCount;

uint16_t AvailableBufferLength =
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11 changes: 11 additions & 0 deletions src/core/packet_builder.c
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Original file line number Diff line number Diff line change
Expand Up @@ -997,6 +997,17 @@ QuicPacketBuilderFinalize(
Builder->Path,
Builder->Metadata);

//
// Per RFC 9001 s4.9.1, a client MUST discard Initial keys when it first
// sends a Handshake packet. This must happen on ANY Handshake packet
// (not just those carrying CRYPTO frames) so that Initial bytes in flight
// are released from congestion control and the TLS Finished can be sent.
//
if (QuicConnIsClient(Connection) &&
Builder->Key->Type == QUIC_PACKET_KEY_HANDSHAKE) {
QuicCryptoDiscardKeys(&Connection->Crypto, QUIC_PACKET_KEY_INITIAL);
}

Builder->Metadata->FrameCount = 0;

if (Builder->Metadata->Flags.IsAckEliciting) {
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36 changes: 17 additions & 19 deletions src/platform/tls_openssl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3321,25 +3321,23 @@ CxPlatTlsProcessData(

Exit:

if (!(TlsContext->ResultFlags & CXPLAT_TLS_RESULT_ERROR)) {
if (State->WriteKeys[QUIC_PACKET_KEY_HANDSHAKE] != NULL &&
State->BufferOffsetHandshake == 0) {
State->BufferOffsetHandshake = State->BufferTotalLength;
QuicTraceLogConnInfo(
OpenSslHandshakeDataStart,
TlsContext->Connection,
"Writing Handshake data starts at %u",
State->BufferOffsetHandshake);
}
if (State->WriteKeys[QUIC_PACKET_KEY_1_RTT] != NULL &&
State->BufferOffset1Rtt == 0) {
State->BufferOffset1Rtt = State->BufferTotalLength;
QuicTraceLogConnInfo(
OpenSsl1RttDataStart,
TlsContext->Connection,
"Writing 1-RTT data starts at %u",
State->BufferOffset1Rtt);
}
if (State->WriteKeys[QUIC_PACKET_KEY_HANDSHAKE] != NULL &&
State->BufferOffsetHandshake == 0) {
State->BufferOffsetHandshake = State->BufferTotalLength;
QuicTraceLogConnInfo(
OpenSslHandshakeDataStart,
TlsContext->Connection,
"Writing Handshake data starts at %u",
State->BufferOffsetHandshake);
}
if (State->WriteKeys[QUIC_PACKET_KEY_1_RTT] != NULL &&
State->BufferOffset1Rtt == 0) {
State->BufferOffset1Rtt = State->BufferTotalLength;
QuicTraceLogConnInfo(
OpenSsl1RttDataStart,
TlsContext->Connection,
"Writing 1-RTT data starts at %u",
State->BufferOffset1Rtt);
}

return TlsContext->ResultFlags;
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36 changes: 17 additions & 19 deletions src/platform/tls_quictls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2145,25 +2145,23 @@ CxPlatTlsProcessData(

Exit:

if (!(TlsContext->ResultFlags & CXPLAT_TLS_RESULT_ERROR)) {
if (State->WriteKeys[QUIC_PACKET_KEY_HANDSHAKE] != NULL &&
State->BufferOffsetHandshake == 0) {
State->BufferOffsetHandshake = State->BufferTotalLength;
QuicTraceLogConnInfo(
OpenSslHandshakeDataStart,
TlsContext->Connection,
"Writing Handshake data starts at %u",
State->BufferOffsetHandshake);
}
if (State->WriteKeys[QUIC_PACKET_KEY_1_RTT] != NULL &&
State->BufferOffset1Rtt == 0) {
State->BufferOffset1Rtt = State->BufferTotalLength;
QuicTraceLogConnInfo(
OpenSsl1RttDataStart,
TlsContext->Connection,
"Writing 1-RTT data starts at %u",
State->BufferOffset1Rtt);
}
if (State->WriteKeys[QUIC_PACKET_KEY_HANDSHAKE] != NULL &&
State->BufferOffsetHandshake == 0) {
State->BufferOffsetHandshake = State->BufferTotalLength;
QuicTraceLogConnInfo(
OpenSslHandshakeDataStart,
TlsContext->Connection,
"Writing Handshake data starts at %u",
State->BufferOffsetHandshake);
}
if (State->WriteKeys[QUIC_PACKET_KEY_1_RTT] != NULL &&
State->BufferOffset1Rtt == 0) {
State->BufferOffset1Rtt = State->BufferTotalLength;
QuicTraceLogConnInfo(
OpenSsl1RttDataStart,
TlsContext->Connection,
"Writing 1-RTT data starts at %u",
State->BufferOffset1Rtt);
}

return TlsContext->ResultFlags;
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