Added support for "noise" over I1P/Tor to mask Tx transmission.

src/cryptonote_protocol/levin_notify.h

@@ -0,0 +1,132 @@
+// Copyright (c) 2019, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once
+
+#include <boost/asio/io_service.hpp>
+#include <boost/uuid/uuid.hpp>
+#include <memory>
+#include <vector>
+
+#include "byte_slice.h"
+#include "cryptonote_basic/blobdatatype.h"
+#include "net/enums.h"
+#include "span.h"
+
+namespace epee
+{
+namespace levin
+{
+    template<typename> class async_protocol_handler_config;
+}
+}
+
+namespace nodetool
+{
+  template<typename> struct p2p_connection_context_t;
+}
+
+namespace cryptonote
+{
+  struct cryptonote_connection_context;
+}
+
+namespace cryptonote
+{
+namespace levin
+{
+  namespace detail
+  {
+    using p2p_context = nodetool::p2p_connection_context_t<cryptonote::cryptonote_connection_context>;
+    struct zone; //!< Internal data needed for zone notifications
+  } // detail
+
+  using connections = epee::levin::async_protocol_handler_config<detail::p2p_context>;
+
+  //! Provides tx notification privacy
+  class notify
+  {
+    std::shared_ptr<detail::zone> zone_;
+
+  public:
+    struct status
+    {
+      bool has_noise;
+      bool connections_filled;
+    };
+
+    //! Construct an instance that cannot notify.
+    notify() noexcept
+      : zone_(nullptr)
+    {}
+
+    //! Construct an instance with available notification `zones`.
+    explicit notify(boost::asio::io_service& service, std::shared_ptr<connections> p2p, epee::byte_slice noise);
+
+    notify(const notify&) = delete;
+    notify(notify&&) = default;
+
+    ~notify() noexcept;
+
+    notify& operator=(const notify&) = delete;
+    notify& operator=(notify&&) = default;
+
+    //! \return Status information for zone selection.
+    status get_status() const noexcept;
+
+    //! Probe for new outbound connection - skips if not needed.
+    void new_out_connection();
+
+    //! Run the logic for the next epoch immediately. Only use in testing.
+    void run_epoch();
+
+    //! Run the logic for the next stem timeout imemdiately. Only use in  testing.
+    void run_stems();
+
+    /*! Send txs using `cryptonote_protocol_defs.h` payload format wrapped in a
+        levin header. The message will be sent in a "discreet" manner if
+        enabled - if `!noise.empty()` then the `command`/`payload` will be
+        queued to send at the next available noise interval. Otherwise, a
+        standard Monero flood notification will be used.
+
+        \note Eventually Dandelion++ stem sending will be used here when
+          enabled.
+
+        \param txs The transactions that need to be serialized and relayed.
+        \param source The source of the notification. `is_nil()` indicates this
+          node is the source. Dandelion++ will use this to map a source to a
+          particular stem.
+        \param pad_txs A request to pad txs to help conceal origin via
+          statistical analysis. Ignored if noise was enabled during
+          construction.
+
+      \return True iff the notification is queued for sending. */
+    bool send_txs(std::vector<blobdata> txs, const boost::uuids::uuid& source, bool pad_txs);
+  };
+} // levin
+} // net