public static void SendMessage(this IOutgoingSocket socket, KernelContext context, Message message)
{
// FIXME: need to handle parents for messages which are handled
// sequentially.
// Conceptually, sending a message consists of three steps:
// • Convert the message to four frames.
// • Digest the four frames.
// • Send the identities, the delimeter, the digest, and the
// message frames.
var zmqMessage = new NetMQMessage();
var frames = new[]
{
message.Header,
message.ParentHeader,
message.Metadata,
message.Content
}
.Select(frame => JsonConvert.SerializeObject(frame))
.Select(str => Encoding.UTF8.GetBytes(str))
.ToList();
var digest = context.NewHmac().ComputeHash(frames.ToArray());
message.ZmqIdentities?.ForEach(ident => zmqMessage.Append(ident));
zmqMessage.Append("<IDS|MSG>");
zmqMessage.Append(BitConverter.ToString(digest).Replace("-", "").ToLowerInvariant());
frames.ForEach(ident => zmqMessage.Append(ident));
socket.SendMultipartMessage(zmqMessage);
}
public HeartbeatServer(
ILogger <HeartbeatServer> logger,
IOptions <KernelContext> context
)
{
this.logger = logger;
this.context = context.Value;
}
public ShellServer(
ILogger <ShellServer> logger,
IOptions <KernelContext> context,
IServiceProvider provider
)
{
this.logger = logger;
this.context = context.Value;
this.provider = provider;
}
public ShellServer(
ILogger <ShellServer> logger,
IOptions <KernelContext> context,
IServiceProvider provider,
IShellRouter router
)
{
this.logger = logger;
this.context = context.Value;
this.provider = provider;
this.router = router;
router.RegisterHandler("kernel_info_request", async message => KernelInfoRequest?.Invoke(message));
router.RegisterHandler("shutdown_request", async message => ShutdownRequest?.Invoke(message));
}
/// <summary>
/// Receives an entire Jupyter wire protocol message from a given
/// ZeroMQ socket and deserializes it to a Message object for
/// further processing.
/// </summary>
public static Message ReceiveMessage(
this NetMQSocket socket,
KernelContext context,
Encoding encoding = null
)
{
encoding = encoding ?? Encoding.UTF8;
// Get all the relevant message frames.
var rawFrames = socket
.ReceiveMultipartBytes();
var frames = rawFrames
.Select(frame => encoding.GetString(frame))
.ToList();
// We know that one of the frames should be the special delimiter
// <IDS|MSG>. If we don't find it, time to throw an exception.
var idxDelimiter = frames.IndexOf("<IDS|MSG>");
if (idxDelimiter < 0)
{
throw new ProtocolViolationException("Expected <IDS|MSG> delimiter, but none was present.");
}
// At this point, we know that everything before idxDelimter is
// a ZMQ identity, and that everything after follows the Jupyter
// wire protocol. In particular, the next five blobs after <IDS|MSG>
// are as follows:
// • An HMAC signature for the entire message.
// • A serialized header for this message.
// • A serialized header for the previous message in sequence.
// • A serialized metadata dictionary.
// • A serialized content dictionary.
// Any remaining blobs are extra raw data buffers.
// We start by computing the digest, since that is much, much easier
// to do given the raw frames than trying to unambiguously
// reserialize everything.
// To compute the digest and verify the message, we start by pulling
// out the claimed signature. This is by default a string of
// hexadecimal characters, so we convert to a byte[] for comparing
// with the HMAC output.
var signature = frames[idxDelimiter + 1].HexToBytes();
// Next, we take the four frames after the <IDS|MSG> delimeter, since
// those are the subject of the digest.
var toDigest = rawFrames.Skip(idxDelimiter + 2).Take(4).ToArray();
var digest = context.NewHmac().ComputeHash(toDigest);
if (!signature.IsEqual(digest))
{
var digestStr = Convert.ToBase64String(digest);
var signatureStr = Convert.ToBase64String(signature);
throw new ProtocolViolationException(
$"HMAC {digestStr} did not agree with {signatureStr}.");
}
// If we made it this far, we can unpack the content of the message
// into the right subclass of MessageContent.
var header = JsonConvert.DeserializeObject <MessageHeader>(frames[idxDelimiter + 2]);
var content = MessageContent.Deserializers.GetValueOrDefault(
header.MessageType,
data =>
new UnknownContent
{
Data = JsonConvert.DeserializeObject <Dictionary <string, object> >(data)
}
)(frames[idxDelimiter + 5]);
var message = new Message
{
ZmqIdentities = rawFrames.Take(idxDelimiter).ToList(),
Signature = signature,
Header = header,
ParentHeader = JsonConvert.DeserializeObject <MessageHeader>(frames[idxDelimiter + 3]),
Metadata = JsonConvert.DeserializeObject <Dictionary <string, object> >(frames[idxDelimiter + 4]),
Content = content
};
return(message);
}
