public static bool TryParseProtectedByConnectionId(IAead aead,
ICipher cipher,
MemoryCursor cursor,
PacketConnectionId connectionId,
PacketNumber largestAcknowledgedPacketNumber,
out ShortPacket result)
{
result = new ShortPacket();
var startOffset = cursor.AsOffset();
var firstByte = PacketFirstByte.Parse(cursor.Peek(1).Span[0]);
if (!firstByte.IsShortHeader())
{
return(false);
}
cursor.Move(1);
if (!connectionId.TrySliceValue(cursor))
{
return(false);
}
var payload = PacketPayload.SliceShortProtectedPacketBytes(cursor, aead, cipher, startOffset, firstByte, largestAcknowledgedPacketNumber, out var packetNumber);
result = new ShortPacket(connectionId, packetNumber, payload);
return(true);
}
public static PacketPayload.CursorWritingContext StartWriting(MemoryCursor cursor,
PacketVersion version,
PacketConnectionId destinationConnectionId,
PacketConnectionId sourceConnectionId,
PacketNumber packetNumber,
PacketToken token)
{
var startOffset = cursor.AsOffset();
var firstByte = new PacketFirstByte()
.SetInitial()
.SetMaxPacketNumberLength();
firstByte.Write(cursor);
version.WriteBytes(cursor);
destinationConnectionId.WriteBytes(cursor);
sourceConnectionId.WriteBytes(cursor);
token.WriteBytes(cursor);
var context = PacketPayload.StartPacketWriting(cursor, startOffset);
var packetNumberBytes = firstByte.SlicePacketNumberBytes(cursor);
packetNumber.Fill(packetNumberBytes.Span);
return(context);
}
public static PacketPayload.CursorWritingContext StartWriting(MemoryCursor cursor,
PacketVersion version,
PacketConnectionId destinationConnectionId,
PacketConnectionId sourceConnectionId,
PacketNumber largestAcknowledgedPacketNumber,
PacketNumber packetNumber)
{
var startOffset = cursor.AsOffset();
var firstByte = new PacketFirstByte()
.SetHandshake()
.SetMaxPacketNumberLength();
firstByte.Write(cursor);
version.WriteBytes(cursor);
destinationConnectionId.WriteBytes(cursor);
sourceConnectionId.WriteBytes(cursor);
var context = PacketPayload.StartPacketWriting(cursor, startOffset);
var packetNumberBytes = firstByte.SlicePacketNumberBytes(cursor);
packetNumber
.EncodeByLargestAcknowledged(largestAcknowledgedPacketNumber)
.Fill(packetNumberBytes.Span);
return(context);
}
public static bool TryParse(MemoryCursor cursor, PacketNumber largestAcknowledgedPacketNumber, out HandshakePacket result)
{
result = new HandshakePacket();
var startOffset = cursor.AsOffset();
var firstByte = PacketFirstByte.Parse(cursor.Peek(1).Span[0]);
if (!firstByte.IsHandshakeType())
{
return(false);
}
cursor.Move(1);
var version = PacketVersion.Parse(cursor);
var destinationConnectionId = PacketConnectionId.Parse(cursor);
var sourceConnectionId = PacketConnectionId.Parse(cursor);
var payload = PacketPayload.SlicePacketBytes(cursor, firstByte, startOffset, largestAcknowledgedPacketNumber, out var packetNumber);
result = new HandshakePacket(version,
destinationConnectionId,
sourceConnectionId,
packetNumber,
payload);
return(true);
}
private ShortPacket(PacketConnectionId destinationConnectionId,
PacketNumber number,
MemoryBuffer payload)
{
DestinationConnectionId = destinationConnectionId;
Number = number;
Payload = payload;
}
public static LongProtectedWritingContext StartLongProtectedPacketWriting(
MemoryCursor cursor,
IAead aead,
ICipher cipher,
int startPacketOffset,
PacketFirstByte firstByte,
PacketNumber packetNumber,
PacketNumber?largestAcknowledgedPacketNumber)
{
return(new LongProtectedWritingContext(aead, cipher, cursor, startPacketOffset, cursor.AsOffset(), packetNumber, largestAcknowledgedPacketNumber, firstByte));
}
private HandshakePacket(PacketVersion version,
PacketConnectionId destinationConnectionId,
PacketConnectionId sourceConnectionId,
PacketNumber number,
MemoryBuffer payload)
{
Version = version;
DestinationConnectionId = destinationConnectionId;
SourceConnectionId = sourceConnectionId;
Number = number;
Payload = payload;
}
private InitialPacket(PacketVersion version,
PacketConnectionId destinationConnectionId,
PacketConnectionId sourceConnectionId,
PacketToken token,
PacketNumber number,
MemoryBuffer payload)
{
Version = version;
DestinationConnectionId = destinationConnectionId;
SourceConnectionId = sourceConnectionId;
Token = token;
Number = number;
Payload = payload;
}
public LongProtectedWritingContext(
IAead aead,
ICipher cipher,
MemoryCursor cursor,
int startPacketOffset,
int startPayloadOffset,
PacketNumber packetNumber,
PacketNumber?largestAcknowledgedPacketNumber,
PacketFirstByte packetFirstByte)
{
this.aead = aead;
this.cipher = cipher;
this.cursor = cursor;
this.startPacketOffset = startPacketOffset;
this.startPayloadOffset = startPayloadOffset;
this.packetNumber = packetNumber;
this.largestAcknowledgedPacketNumber = largestAcknowledgedPacketNumber;
this.packetFirstByte = packetFirstByte;
}
public static MemoryBuffer SliceShortProtectedPacketBytes(
MemoryCursor cursor,
IAead aead,
ICipher cipher,
int startPacketOffset,
PacketFirstByte firstByte,
PacketNumber largestAcknowledgedPacketNumber,
out PacketNumber packetNumber)
{
var startPacketNumberOffset = cursor.AsOffset();
cursor.Move(SkipToSampleLength);
var sample = cursor.Move(SampleLength);
var mask = cipher.CreateMask(sample.Span);
cursor.Set(startPacketOffset);
firstByte.Mask(mask).Write(cursor);
cursor.Set(startPacketNumberOffset);
var packetNumberBytes = firstByte.Mask(mask).SlicePacketNumberBytes(cursor);
var headerLength = cursor - startPacketOffset;
var headerBytes = cursor.Peek(-headerLength);
var startPayloadOffset = cursor.AsOffset();
cursor.MoveEnd();
var tagBytes = cursor.Move(-aead.TagLength);
var payloadLength = cursor - startPayloadOffset;
var payloadBytes = cursor.Peek(-payloadLength);
var payload = cursor.Slice(-payloadLength);
var encodedPacketNumber = PacketNumber.Parse(packetNumberBytes.Span, mask);
encodedPacketNumber.Fill(packetNumberBytes.Span);
packetNumber = encodedPacketNumber.DecodeByLargestAcknowledged(largestAcknowledgedPacketNumber);
packetNumber.Decrypt(aead, payloadBytes.Span, tagBytes.Span, headerBytes.Span);
cursor.MoveEnd();
return(payload);
}
public static MemoryBuffer SlicePacketBytes(
MemoryCursor cursor,
PacketFirstByte firstByte,
int startPacketOffset,
PacketNumber?largestAcknowledgedPacketNumber,
out PacketNumber packetNumber)
{
var readLength = cursor - startPacketOffset;
var packetLength = cursor.DecodeVariable32();
var packetNumberBytes = firstByte.SlicePacketNumberBytes(cursor);
var payloadLength = packetLength - readLength - packetNumberBytes.Length;
packetNumber = PacketNumber.Parse(packetNumberBytes.Span);
if (largestAcknowledgedPacketNumber.HasValue)
{
packetNumber = packetNumber.DecodeByLargestAcknowledged(largestAcknowledgedPacketNumber.Value);
}
return(cursor.Slice(payloadLength));
}
public static PacketPayload.LongProtectedWritingContext StartProtectedWriting(IAead aead,
ICipher cipher,
MemoryCursor cursor,
PacketVersion version,
PacketConnectionId destinationConnectionId,
PacketConnectionId sourceConnectionId,
PacketNumber packetNumber,
PacketToken token)
{
var startPacketOffset = cursor.AsOffset();
var firstByte = new PacketFirstByte()
.SetInitial()
.SetMaxPacketNumberLength();
firstByte.Write(cursor);
version.WriteBytes(cursor);
destinationConnectionId.WriteBytes(cursor);
sourceConnectionId.WriteBytes(cursor);
token.WriteBytes(cursor);
return(PacketPayload.StartLongProtectedPacketWriting(cursor, aead, cipher, startPacketOffset, firstByte, packetNumber, null));
}
public static PacketPayload.ShortProtectedWritingContext StartProtectedWriting(IAead aead,
ICipher cipher,
MemoryCursor cursor,
PacketConnectionId destinationConnectionId,
PacketNumber packetNumber,
PacketNumber largestAcknowledgedPacketNumber)
{
var startOffset = cursor.AsOffset();
var firstByte = new PacketFirstByte().SetShort();
firstByte.Write(cursor);
destinationConnectionId.WriteValueBytes(cursor);
return(PacketPayload.StartShortProtectedPacketWriting(cursor, aead, cipher, startOffset, firstByte, packetNumber, largestAcknowledgedPacketNumber));
}