public async void TwoUnevenPiecesValid()
{
var expectedDigest = "aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d".FromHex();
var verified = new VerifiedBytes(expectedDigest, 5, 3);
// Piece indicies need to be in range.
Assert.Throws <ArgumentOutOfRangeException>(() => {
verified.ProvidePiece(-1, "hel".ToASCII());
});
Assert.Throws <ArgumentOutOfRangeException>(() => {
verified.ProvidePiece(2, "hel".ToASCII());
});
// Pieces need to be of the expected size.
Assert.Throws <ArgumentException>(() => {
verified.ProvidePiece(0, "lo".ToASCII());
});
Assert.Throws <ArgumentException>(() => {
verified.ProvidePiece(1, "hel".ToASCII());
});
verified.ProvidePiece(1, "lo".ToASCII());
verified.ProvidePiece(0, "hel".ToASCII());
// Each piece can only be provided once.
Assert.Throws <VerifiedBytesStateException>(() => {
verified.ProvidePiece(0, "hel".ToASCII());
});
var resultValue = await verified.Result;
Assert.Equal("hello".ToASCII(), resultValue);
}
public async void ZeroLengthInvalid()
{
var expectedDigest = "0000000000000000000000000000000000000000".FromHex();
var verified = new VerifiedBytes(expectedDigest, 0, 1024);
await Assert.ThrowsAsync <BytesVerificationException>(async() => {
var resultValue = await verified.Result;
});
}
public async void TwoUnevenPiecesInvalidFromVerified()
{
var expectedDigest = "0000000000000000000000000000000000000000".FromHex();
var verified = VerifiedBytes.From("hello".ToASCII(), expectedDigest, 3);
await Assert.ThrowsAsync <BytesVerificationException>(async() => {
await verified.Result;
});
}
public async void TwoUnevenPiecesTogetherValid()
{
var expectedDigest = "aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d".FromHex();
var verified = new VerifiedBytes(expectedDigest, 5, 3);
verified.ProvideData("hello".ToASCII());
var resultValue = await verified.Result;
Assert.Equal("hello".ToASCII(), resultValue);
Assert.Equal("hel".ToASCII(), verified.GetPiece(0));
Assert.Equal("lo".ToASCII(), verified.GetPiece(1));
Assert.Equal("hello".ToASCII(), verified.GetData());
}
public async void TwoUnevenPiecesTogetherInvalid()
{
var expectedDigest = "aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d".FromHex();
var verified = new VerifiedBytes(expectedDigest, 5, 3);
verified.ProvideData("hell!".ToASCII());
// Data can only be provided once, even it would fix it.
Assert.Throws <VerifiedBytesStateException>(() => {
verified.ProvideData("hello".ToASCII());
});
await Assert.ThrowsAsync <BytesVerificationException>(async() => {
var resultValue = await verified.Result;
});
}
public async void ZeroLengthValid()
{
var expectedDigest = "da39a3ee5e6b4b0d3255bfef95601890afd80709".FromHex();
var verified = new VerifiedBytes(expectedDigest, 0, 1024);
var resultValue = await verified.Result;
Assert.Equal(new byte[0], resultValue);
Assert.Equal(new byte[0], verified.GetData());
// No possible indices are valid.
Assert.Throws <ArgumentOutOfRangeException>(() => {
verified.ProvidePiece(0, new byte[0]);
});
Assert.Throws <ArgumentOutOfRangeException>(() => {
verified.ProvidePiece(0, new byte[0]);
Assert.Equal("".ToASCII(), verified.GetPiece(0));
});
}
public async void TwoUnevenPiecesValidFromVerified()
{
var expectedDigest = "aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d".FromHex();
var verified = VerifiedBytes.From("hello".ToASCII(), expectedDigest, 3);
Assert.Equal(expectedDigest, verified.Digest);
var resultValue = await verified.Result;
Assert.Equal("hello".ToASCII(), resultValue);
// Data can only be provided once.
Assert.Throws <VerifiedBytesStateException>(() => {
verified.ProvideData("hello".ToASCII());
});
Assert.Throws <VerifiedBytesStateException>(() => {
verified.ProvidePiece(0, "hel".ToASCII());
});
}
// ourExtCode refers to the value we have associated with ut_metadata
// theirExtCode refers to the value they have associated with ut_metadata
public byte[] GetMetadata(NetworkStream stream, TcpClient connection, byte ourExtCode, byte theirExtCode, byte[] infohash)
{
if (!connection.Connected)
{
throw new Exception("Disconnected from peer after handshake.");
}
var currentPiece = 0;
var info = new VerifiedBytes(infohash, (Int32)metadataLength, CommonPieceSizes.BEP9_METADATA);
using (logger.BeginScope($"Metadata request for {infohash.ToHex()} from {connection.Client.RemoteEndPoint}"))
{
// Request the first piece.
var initialRequest = ConstructRequestMessage(ourExtCode, 0);
logger.LogInformation(LoggingEvents.METADATA_REQUEST, "Sending request for first metadata piece: " + initialRequest.ToHuman());
stream.Write(initialRequest);
while (true)
{
Int32 theirLength = 0;
// Read lengths until we get a non-zero (non-keepalive) length.
while (theirLength == 0)
{
var theirPrefix = stream.ReadBytes(4);
theirLength = theirPrefix.Decode32BitInteger();
if (theirLength == 0)
{
logger.LogInformation(LoggingEvents.PEER_PROTOCOL_MSG, "Got keepalive. Let's send our own!");
stream.Write(new byte[4]);
}
}
logger.LogInformation(LoggingEvents.PEER_PROTOCOL_MSG, $"Got message with length {theirLength}.");
var peerResponse = stream.ReadBytes(theirLength);
var responseTypeId = peerResponse[0];
switch (responseTypeId)
{
case 20:
logger.LogInformation(LoggingEvents.EXTENSION_MESSAGE, "It's an extension message! Hurrah!");
var extensionId = peerResponse[1];
if (extensionId == theirExtCode)
{
logger.LogInformation(LoggingEvents.METADATA_RESPONSE_INCOMING, "It's a metadata exchange message!");
var data = peerResponse.Slice(2);
var dict = Bencoding.DecodeFirstDict(data, out Int64 dictSize);
var postDict = data.Slice((Int32)dictSize); // This is the metadata itself -- a bencoded dictionary of utf8 strings
if (dict.GetInt("piece") != currentPiece)
{
throw new Exception($"Expected piece {currentPiece}. Instead, received {dict.GetInt("piece")}");
}
logger.LogInformation(
LoggingEvents.METADATA_RESPONSE_INCOMING,
$"Got BEP-9 {Bencoding.ToHuman(Bencoding.Encode(dict))} followed by {postDict.Length} bytes of data.\nStoring...");
info.ProvidePiece(currentPiece, postDict);
currentPiece++;
if (currentPiece == info.PieceCount)
{
byte[] combinedPieces;
try {
combinedPieces = info.Result.Result;
} catch (BytesVerificationException ex) {
logger.LogWarning(LoggingEvents.METADATA_FAILURE, "metadata verification failed!", ex);
throw new MetadataException("Metadata verification failed -- try another peer.");
}
logger.LogInformation(LoggingEvents.DATA_STORAGE_ACTION, "metadata verified! saving...");
DataHandler.SaveMetadata(combinedPieces);
logger.LogInformation(LoggingEvents.DATA_STORAGE_ACTION, "metadata saved.");
return(combinedPieces);
}
var request = ConstructRequestMessage(ourExtCode, currentPiece);
logger.LogInformation(LoggingEvents.METADATA_REQUEST, "Requesting the next piece of metadata...");
stream.Write(request);
}
else
{
logger.LogWarning(LoggingEvents.PEER_UNEXPECTED_RESPONSE, $"It's an unexpected message type, ID {extensionId}.");
}
break;
case 0:
logger.LogInformation(LoggingEvents.PEER_PROTOCOL_MSG, "It's a choke message! :(");
break;
case 1:
logger.LogInformation(LoggingEvents.PEER_PROTOCOL_MSG, "It's an unchoke message! :D");
break;
case 2:
logger.LogInformation(LoggingEvents.PEER_PROTOCOL_MSG, "It's an interested message! <3");
break;
case 4:
logger.LogInformation(LoggingEvents.PEER_PROTOCOL_MSG, "It's a not interested message! </3");
break;
default:
logger.LogWarning(LoggingEvents.PEER_UNEXPECTED_RESPONSE, $"Unexpected message type {responseTypeId}; ignoring.");
break;
}
}
}
}
