quic_session.h

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// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the Apache 2.0 License.
#pragma once
 
#include "ds/internal_logger.h"
#include "ds/messaging.h"
#include "ds/pending_io.h"
#include "ds/ring_buffer.h"
#include "enclave/session.h"
#include "udp/msg_types.h"
 
#include <exception>
 
namespace quic
{
  class QUICSession : public ccf::Session,
                      public std::enable_shared_from_this<QUICSession>
  {
  protected:
    ringbuffer::WriterPtr to_host;
    ccf::tls::ConnID session_id;
 
    std::shared_ptr<ccf::tasks::OrderedTasks> task_scheduler;
 
    enum Status : std::uint8_t
    {
      handshake,
      ready,
      closed,
      authfail,
      error
    };
 
    Status get_status() const
    {
      return status;
    }
 
    using PendingBuffer = PendingIO<uint8_t>;
    using PendingList = std::vector<PendingBuffer>;
    PendingList pending_writes;
    PendingList pending_reads;
 
  private:
    // Decrypted data
    std::vector<uint8_t> read_buffer;
 
    Status status = handshake;
 
  public:
    QUICSession(
      int64_t session_id_, ringbuffer::AbstractWriterFactory& writer_factory_) :
      to_host(writer_factory_.create_writer_to_outside()),
      session_id(session_id_)
    {
      task_scheduler = ccf::tasks::OrderedTasks::create(
        ccf::tasks::get_main_job_board(),
        fmt::format("Session {}", session_id));
    }
 
    ~QUICSession() override
    {
      task_scheduler->cancel_task();
      // RINGBUFFER_WRITE_MESSAGE(quic::quic_closed, to_host, session_id);
    }
 
    std::string hostname()
    {
      return {};
    }
 
    std::vector<uint8_t> peer_cert()
    {
      return {};
    }
 
    // Returns count N of bytes read, which will be the first N bytes of data,
    // up to a maximum of size. If exact is true, will only return either size
    // or 0 (when size bytes are not currently available). data may be accessed
    // beyond N during operation, up to size, but only the first N should be
    // used by caller.
    size_t read(uint8_t* data, size_t size, sockaddr addr, bool exact = false)
    {
      LOG_TRACE_FMT("Requesting up to {} bytes", size);
 
      // This will return empty if the connection isn't
      // ready, but it will not block on the handshake.
      do_handshake();
 
      if (status != ready)
      {
        return 0;
      }
 
      // Send pending writes.
      flush();
 
      size_t offset = 0;
 
      if (!read_buffer.empty())
      {
        LOG_TRACE_FMT(
          "Have existing read_buffer of size: {}", read_buffer.size());
        offset = std::min(size, read_buffer.size());
        ::memcpy(data, read_buffer.data(), offset);
 
        if (offset < read_buffer.size())
        {
          read_buffer.erase(read_buffer.begin(), read_buffer.begin() + offset);
        }
        else
        {
          read_buffer.clear();
        }
 
        if (offset == size)
        {
          return size;
        }
 
        // NB: If we continue past here, read_buffer is empty
      }
 
      // This will need to be handled by the actual QUIC stack
      auto r = handle_recv(data + offset, size - offset, addr);
      LOG_TRACE_FMT("quic read returned: {}", r);
 
      if (r < 0)
      {
        LOG_TRACE_FMT("QUIC {} error on read", session_id);
        stop(error);
        return 0;
      }
 
      auto total = r + offset;
 
      // We read _some_ data but not enough, and didn't get
      // WANT_READ. Probably hit an internal size limit - try
      // again
      if (exact && (total < size))
      {
        LOG_TRACE_FMT(
          "Asked for exactly {}, received {}, retrying", size, total);
        read_buffer.insert(read_buffer.end(), data, data + total);
        return read(data, size, addr, exact);
      }
 
      return total;
    }
 
    void recv_buffered(const uint8_t* data, size_t size, sockaddr addr)
    {
      LOG_TRACE_FMT("QUIC Session recv_buffered with {} bytes", size);
      pending_reads.emplace_back(const_cast<uint8_t*>(data), size, addr);
      do_handshake();
    }
 
    struct SessionDataTask : public ccf::tasks::ITaskAction
    {
      std::shared_ptr<QUICSession> self;
      std::vector<uint8_t> data;
      sockaddr addr{};
 
      SessionDataTask(
        std::shared_ptr<QUICSession> s,
        std::span<const uint8_t> d,
        sockaddr sa) :
        self(std::move(s)),
        addr(sa)
      {
        data.assign(d.begin(), d.end());
      }
    };
 
    struct SendDataTask : public SessionDataTask
    {
      using SessionDataTask::SessionDataTask;
 
      void do_action() override
      {
        self->send_raw_thread(data, addr);
      }
 
      [[nodiscard]] const std::string& get_name() const override
      {
        static const std::string name = "quic::SendDataTask";
        return name;
      }
    };
 
    struct RecvDataTask : public SessionDataTask
    {
      using SessionDataTask::SessionDataTask;
 
      void do_action() override
      {
        self->recv(data.data(), data.size(), addr);
      }
 
      [[nodiscard]] const std::string& get_name() const override
      {
        static const std::string name = "quic::RecvDataTask";
        return name;
      }
    };
 
    void send_raw(const uint8_t* data, size_t size, sockaddr addr)
    {
      task_scheduler->add_action(std::make_shared<SendDataTask>(
        shared_from_this(), std::span<const uint8_t>{data, size}, addr));
    }
 
    void send_raw_thread(const std::vector<uint8_t>& data, sockaddr addr)
    {
      // Writes as much of the data as possible. If the data cannot all
      // be written now, we store the remainder. We
      // will try to send pending writes again whenever write() is called.
      do_handshake();
 
      if (status == handshake)
      {
        pending_writes.emplace_back(
          const_cast<uint8_t*>(data.data()), data.size(), addr);
        return;
      }
 
      if (status != ready)
      {
        return;
      }
 
      pending_writes.emplace_back(
        const_cast<uint8_t*>(data.data()), data.size(), addr);
 
      flush();
    }
 
    void send_buffered(const std::vector<uint8_t>& data, sockaddr addr)
    {
      pending_writes.emplace_back(
        const_cast<uint8_t*>(data.data()), data.size(), addr);
    }
 
    void handle_incoming_data(std::span<const uint8_t> data) override
    {
      auto [_, addr_family, addr_data, body] =
        ringbuffer::read_message<udp::udp_inbound>(data);
 
      task_scheduler->add_action(std::make_shared<RecvDataTask>(
        shared_from_this(),
        body,
        udp::sockaddr_decode(addr_family, addr_data)));
    }
 
    virtual void recv(const uint8_t* data_, size_t size_, sockaddr addr_) = 0;
 
    void flush()
    {
      do_handshake();
 
      if (status != ready)
      {
        return;
      }
 
      for (auto& write : pending_writes)
      {
        LOG_TRACE_FMT("QUIC write_some {} bytes", write.len);
 
        // This will need to be handled by the actual QUIC stack
        int rc = handle_send(write.req, write.len, write.addr);
        if (rc < 0)
        {
          LOG_TRACE_FMT("QUIC {} error on flush", session_id);
          stop(error);
          return;
        }
 
        // Mark for deletion (avoiding invalidating iterator)
        write.clear = true;
      }
 
      // Clear all marked for deletion
      PendingBuffer::clear_empty(pending_writes);
    }
 
    void close_session() override
    {
      auto self = shared_from_this();
      task_scheduler->add_action(
        ccf::tasks::make_basic_action([self]() { self->close_thread(); }));
    }
 
    void close_thread()
    {
      switch (status)
      {
        case handshake:
        {
          LOG_TRACE_FMT("QUIC {} closed during handshake", session_id);
          stop(closed);
          break;
        }
 
        case ready:
        {
          LOG_TRACE_FMT("QUIC {} closed", session_id);
          stop(closed);
          break;
        }
 
        default:
        {
        }
      }
    }
 
  private:
    void do_handshake()
    {
      // This should be called when additional data is written to the
      // input buffer, until the handshake is complete.
      if (status != handshake)
      {
        return;
      }
 
      // This will need to be handled by the actual QUIC stack
      LOG_TRACE_FMT("QUIC do_handshake unimplemented");
      status = ready;
    }
 
    void stop(Status status_)
    {
      switch (status)
      {
        case closed:
        case authfail:
        case error:
          return;
 
        default:
        {
        }
      }
 
      status = status_;
    }
 
    int handle_send(const uint8_t* buf, size_t len, sockaddr addr)
    {
      auto [addr_family, addr_data] = udp::sockaddr_encode(addr);
 
      // Either write all of the data or none of it.
      auto wrote = RINGBUFFER_TRY_WRITE_MESSAGE(
        udp::udp_outbound,
        to_host,
        session_id,
        addr_family,
        addr_data,
        serializer::ByteRange{buf, len});
 
      if (!wrote)
      {
        return -1;
      }
 
      return (int)len;
    }
 
    int handle_recv(uint8_t* buf, size_t len, sockaddr addr)
    {
      size_t len_read = 0;
      for (auto& read : pending_reads)
      {
        // Only handle pending reads that belong to the same address
        if (memcmp((void*)&addr, (void*)&read.addr, sizeof(addr)) != 0)
        {
          continue;
        }
 
        size_t rd = std::min(len, read.len);
        ::memcpy(buf, read.req, rd);
        read.clear = true;
 
        // UDP packets are datagrams, so it's either whole or nothing
        len_read += rd;
        if (len_read >= len)
        {
          break;
        }
      }
 
      // Clear all marked for deletion
      PendingBuffer::clear_empty(pending_reads);
 
      if (len_read > 0)
      {
        return len_read;
      }
      return -1;
    }
  };
 
  // This is a wrapper for the QUICSession so we can use in rpc_sessions
  // Ultimately, this needs to be an HTTP3ServerSession : HTTP3Session :
  // QUICSession
  class QUICEchoSession : public QUICSession
  {
    std::shared_ptr<ccf::RPCMap> rpc_map;
    std::shared_ptr<ccf::RpcHandler> handler;
    std::shared_ptr<ccf::SessionContext> session_ctx;
    int64_t session_id;
    ccf::ListenInterfaceID interface_id;
    sockaddr addr;
 
    void echo()
    {
      pending_reads.swap(pending_writes);
      flush();
    }
 
  public:
    QUICEchoSession(
      std::shared_ptr<ccf::RPCMap> rpc_map_,
      int64_t session_id_,
      ccf::ListenInterfaceID interface_id_,
      ringbuffer::AbstractWriterFactory& writer_factory) :
      QUICSession(session_id_, writer_factory),
      rpc_map(std::move(rpc_map_)),
      session_id(session_id_),
      interface_id(std::move(interface_id_)),
      addr{}
    {}
 
    void send_data(std::vector<uint8_t>&& data) override
    {
      send_raw(data.data(), data.size(), addr);
    }
 
    void recv(const uint8_t* data_, size_t size_, sockaddr addr_) override
    {
      recv_buffered(data_, size_, addr_);
      addr = addr_;
 
      LOG_TRACE_FMT("recv called with {} bytes", size_);
 
      // ECHO SERVER
      echo();
    }
  };
}