Revert "Merge pull request #7136"

This reverts commit 63c7ca07fba2f063c760f786a986fb3e02fb040e, reversing
changes made to 2218e23e84a89e9a1e4c0be5d50f891ab836754f.

20 files changed, 215 insertions, 319 deletions

diff --git a/contrib/epee/include/net/levin_base.h b/contrib/epee/include/net/levin_base.h
index df59a6c44..fce6d4b7e 100644
--- a/contrib/epee/include/net/levin_base.h
+++ b/contrib/epee/include/net/levin_base.h
@@ -31,7 +31,6 @@
 
 #include <cstdint>
 
-#include "byte_stream.h"
 #include "net_utils_base.h"
 #include "span.h"
 
@@ -84,12 +83,11 @@ namespace levin
 
 #define LEVIN_PROTOCOL_VER_0         0
 #define LEVIN_PROTOCOL_VER_1         1
-
  
   template<class t_connection_context = net_utils::connection_context_base>
   struct levin_commands_handler
   {
-    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, byte_stream& buff_out, t_connection_context& context)=0;
+    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, byte_slice& buff_out, t_connection_context& context)=0;
     virtual int notify(int command, const epee::span<const uint8_t> in_buff, t_connection_context& context)=0;
     virtual void callback(t_connection_context& context){};
 
@@ -127,41 +125,12 @@ namespace levin
     }
   }
 
-  //! Provides space for levin (p2p) header, so that payload can be sent without copy
-  class message_writer
-  {
-    byte_slice finalize(uint32_t command, uint32_t flags, uint32_t return_code, bool expect_response);
-  public:
-    using header = bucket_head2;
-
-    explicit message_writer(std::size_t reserve = 8192);
-
-    message_writer(const message_writer&) = delete;
-    message_writer(message_writer&&) = default;
-    ~message_writer() = default;
-    message_writer& operator=(const message_writer&) = delete;
-    message_writer& operator=(message_writer&&) = default;
-
-    //! \return Size of payload (excludes header size).
-    std::size_t payload_size() const noexcept
-    {
-      return buffer.size() < sizeof(header) ? 0 : buffer.size() - sizeof(header);
-    }
-
-    byte_slice finalize_invoke(uint32_t command) { return finalize(command, LEVIN_PACKET_REQUEST, 0, true); }
-    byte_slice finalize_notify(uint32_t command) { return finalize(command, LEVIN_PACKET_REQUEST, 0, false); }
-    byte_slice finalize_response(uint32_t command, uint32_t return_code)
-    {
-      return finalize(command, LEVIN_PACKET_RESPONSE, return_code, false);
-    }
-
-    //! Has space for levin header until a finalize method is used
-    byte_stream buffer;
-  };
-
   //! \return Intialized levin header.
   bucket_head2 make_header(uint32_t command, uint64_t msg_size, uint32_t flags, bool expect_response) noexcept;
 
+  //! \return A levin notification message.
+  byte_slice make_notify(int command, epee::span<const std::uint8_t> payload);
+
   /*! Generate a dummy levin message.
 
       \param noise_bytes Total size of the returned `byte_slice`.
@@ -171,11 +140,12 @@ namespace levin
 
   /*! Generate 1+ levin messages that are identical to the noise message size.
 
-   \param noise_size Each levin message will be identical to this value.
+   \param noise Each levin message will be identical to the size of this
+      message. The bytes from this message will be used for padding.
    \return `nullptr` if `noise.size()` is less than the levin header size.
       Otherwise, a levin notification message OR 2+ levin fragment messages.
       Each message is `noise.size()` in length. */
-  byte_slice make_fragmented_notify(const std::size_t noise_size, int command, message_writer message);
+  byte_slice make_fragmented_notify(const byte_slice& noise, int command, epee::span<const std::uint8_t> payload);
 }
 }
 
diff --git a/contrib/epee/include/net/levin_protocol_handler_async.h b/contrib/epee/include/net/levin_protocol_handler_async.h
index a6816cafc..d062fa877 100644
--- a/contrib/epee/include/net/levin_protocol_handler_async.h
+++ b/contrib/epee/include/net/levin_protocol_handler_async.h
@@ -51,21 +51,6 @@
 #define MIN_BYTES_WANTED	512
 #endif
 
-template<typename context_t>
-void on_levin_traffic(const context_t &context, bool initiator, bool sent, bool error, size_t bytes, const char* category)
-{
-  MCINFO("net.p2p.traffic", context << bytes << " bytes " << (sent ? "sent" : "received") << (error ? "/corrupt" : "")
-      << " for category " << category << " initiated by " << (initiator ? "us" : "peer"));
-}
-
-template<typename context_t>
-void on_levin_traffic(const context_t &context, bool initiator, bool sent, bool error, size_t bytes, int command)
-{
-  char buf[32];
-  snprintf(buf, sizeof(buf),  "command-%u", command);
-  on_levin_traffic(context, initiator, sent, error, bytes, buf);
-}
-
 namespace epee
 {
 namespace levin
@@ -103,10 +88,11 @@ public:
   uint64_t m_max_packet_size;
   uint64_t m_invoke_timeout;
 
-  int invoke(int command, message_writer in_msg, std::string& buff_out, boost::uuids::uuid connection_id);
+  int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out, boost::uuids::uuid connection_id);
   template<class callback_t>
-  int invoke_async(int command, message_writer in_msg, boost::uuids::uuid connection_id, const callback_t &cb, size_t timeout = LEVIN_DEFAULT_TIMEOUT_PRECONFIGURED);
+  int invoke_async(int command, const epee::span<const uint8_t> in_buff, boost::uuids::uuid connection_id, const callback_t &cb, size_t timeout = LEVIN_DEFAULT_TIMEOUT_PRECONFIGURED);
 
+  int notify(int command, const epee::span<const uint8_t> in_buff, boost::uuids::uuid connection_id);
   int send(epee::byte_slice message, const boost::uuids::uuid& connection_id);
   bool close(boost::uuids::uuid connection_id);
   bool update_connection_context(const t_connection_context& contxt);
@@ -136,17 +122,12 @@ class async_protocol_handler
 {
   std::string m_fragment_buffer;
 
-  bool send_message(byte_slice message)
+  bool send_message(uint32_t command, epee::span<const uint8_t> in_buff, uint32_t flags, bool expect_response)
   {
-    if (message.size() < sizeof(message_writer::header))
-      return false;
-
-    message_writer::header head;
-    std::memcpy(std::addressof(head), message.data(), sizeof(head));
-    if(!m_pservice_endpoint->do_send(std::move(message)))
+    const bucket_head2 head = make_header(command, in_buff.size(), flags, expect_response);
+    if(!m_pservice_endpoint->do_send(byte_slice{as_byte_span(head), in_buff}))
       return false;
 
-    on_levin_traffic(m_connection_context, true, true, false, head.m_cb, head.m_command);
     MDEBUG(m_connection_context << "LEVIN_PACKET_SENT. [len=" << head.m_cb
         << ", flags" << head.m_flags
         << ", r?=" << head.m_have_to_return_data
@@ -542,17 +523,26 @@ public:
           {
             if(m_current_head.m_have_to_return_data)
             {
-              levin::message_writer return_message{32 * 1024};
+              byte_slice return_buff;
               const uint32_t return_code = m_config.m_pcommands_handler->invoke(
-                m_current_head.m_command, buff_to_invoke, return_message.buffer, m_connection_context
+                m_current_head.m_command, buff_to_invoke, return_buff, m_connection_context
               );
 
               // peer_id remains unset if dropped
               if (m_current_head.m_command == m_connection_context.handshake_command() && m_connection_context.handshake_complete())
                 m_max_packet_size = m_config.m_max_packet_size;
 
-              if(!send_message(return_message.finalize_response(m_current_head.m_command, return_code)))
+              bucket_head2 head = make_header(m_current_head.m_command, return_buff.size(), LEVIN_PACKET_RESPONSE, false);
+              head.m_return_code = SWAP32LE(return_code);
+
+              if(!m_pservice_endpoint->do_send(byte_slice{{epee::as_byte_span(head), epee::to_span(return_buff)}}))
                 return false;
+
+              MDEBUG(m_connection_context << "LEVIN_PACKET_SENT. [len=" << head.m_cb
+                << ", flags" << head.m_flags
+                << ", r?=" << head.m_have_to_return_data
+                <<", cmd = " << head.m_command
+                << ", ver=" << head.m_protocol_version);
             }
             else
               m_config.m_pcommands_handler->notify(m_current_head.m_command, buff_to_invoke, m_connection_context);
@@ -629,7 +619,7 @@ public:
   }
 
   template<class callback_t>
-  bool async_invoke(int command, message_writer in_msg, const callback_t &cb, size_t timeout = LEVIN_DEFAULT_TIMEOUT_PRECONFIGURED)
+  bool async_invoke(int command, const epee::span<const uint8_t> in_buff, const callback_t &cb, size_t timeout = LEVIN_DEFAULT_TIMEOUT_PRECONFIGURED)
   {
     misc_utils::auto_scope_leave_caller scope_exit_handler = misc_utils::create_scope_leave_handler(
       boost::bind(&async_protocol_handler::finish_outer_call, this));
@@ -648,7 +638,7 @@ public:
       if (command == m_connection_context.handshake_command())
         m_max_packet_size = m_config.m_max_packet_size;
 
-      if(!send_message(in_msg.finalize_invoke(command)))
+      if(!send_message(command, in_buff, LEVIN_PACKET_REQUEST, true))
       {
         LOG_ERROR_CC(m_connection_context, "Failed to do_send");
         err_code = LEVIN_ERROR_CONNECTION;
@@ -674,7 +664,7 @@ public:
     return true;
   }
 
-  int invoke(int command, message_writer in_msg, std::string& buff_out)
+  int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out)
   {
     misc_utils::auto_scope_leave_caller scope_exit_handler = misc_utils::create_scope_leave_handler(
                                       boost::bind(&async_protocol_handler::finish_outer_call, this));
@@ -686,7 +676,7 @@ public:
     if (command == m_connection_context.handshake_command())
       m_max_packet_size = m_config.m_max_packet_size;
 
-    if (!send_message(in_msg.finalize_invoke(command)))
+    if (!send_message(command, in_buff, LEVIN_PACKET_REQUEST, true))
     {
       LOG_ERROR_CC(m_connection_context, "Failed to send request");
       return LEVIN_ERROR_CONNECTION;
@@ -723,9 +713,25 @@ public:
     return m_invoke_result_code;
   }
 
-  /*! Sends `message` without adding a levin header. The message must have been
-      created with `make_noise_notify`, `make_fragmented_notify`, or
-      `message_writer::finalize_notify`. See additional instructions for
+  int notify(int command, const epee::span<const uint8_t> in_buff)
+  {
+    misc_utils::auto_scope_leave_caller scope_exit_handler = misc_utils::create_scope_leave_handler(
+                          boost::bind(&async_protocol_handler::finish_outer_call, this));
+
+    CRITICAL_REGION_LOCAL(m_call_lock);
+
+    if (!send_message(command, in_buff, LEVIN_PACKET_REQUEST, false))
+    {
+      LOG_ERROR_CC(m_connection_context, "Failed to send notify message");
+      return -1;
+    }
+
+    return 1;
+  }
+
+  /*! Sends `message` without adding a levin header. The message must have
+      been created with `make_notify`, `make_noise_notify` or
+      `make_fragmented_notify`. See additional instructions for
       `make_fragmented_notify`.
 
       \return 1 on success */
@@ -735,11 +741,14 @@ public:
       boost::bind(&async_protocol_handler::finish_outer_call, this)
     );
 
-    if (!send_message(std::move(message)))
+    const std::size_t length = message.size();
+    if (!m_pservice_endpoint->do_send(std::move(message)))
     {
       LOG_ERROR_CC(m_connection_context, "Failed to send message, dropping it");
       return -1;
     }
+
+    MDEBUG(m_connection_context << "LEVIN_PACKET_SENT. [len=" << (length - sizeof(bucket_head2)) << ", r?=0]");
     return 1;
   }
   //------------------------------------------------------------------------------------------
@@ -829,19 +838,19 @@ int async_protocol_handler_config<t_connection_context>::find_and_lock_connectio
 }
 //------------------------------------------------------------------------------------------
 template<class t_connection_context>
-int async_protocol_handler_config<t_connection_context>::invoke(int command, message_writer in_msg, std::string& buff_out, boost::uuids::uuid connection_id)
+int async_protocol_handler_config<t_connection_context>::invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out, boost::uuids::uuid connection_id)
 {
   async_protocol_handler<t_connection_context>* aph;
   int r = find_and_lock_connection(connection_id, aph);
-  return LEVIN_OK == r ? aph->invoke(command, std::move(in_msg), buff_out) : r;
+  return LEVIN_OK == r ? aph->invoke(command, in_buff, buff_out) : r;
 }
 //------------------------------------------------------------------------------------------
 template<class t_connection_context> template<class callback_t>
-int async_protocol_handler_config<t_connection_context>::invoke_async(int command, message_writer in_msg, boost::uuids::uuid connection_id, const callback_t &cb, size_t timeout)
+int async_protocol_handler_config<t_connection_context>::invoke_async(int command, const epee::span<const uint8_t> in_buff, boost::uuids::uuid connection_id, const callback_t &cb, size_t timeout)
 {
   async_protocol_handler<t_connection_context>* aph;
   int r = find_and_lock_connection(connection_id, aph);
-  return LEVIN_OK == r ? aph->async_invoke(command, std::move(in_msg), cb, timeout) : r;
+  return LEVIN_OK == r ? aph->async_invoke(command, in_buff, cb, timeout) : r;
 }
 //------------------------------------------------------------------------------------------
 template<class t_connection_context> template<class callback_t>
@@ -920,6 +929,14 @@ void async_protocol_handler_config<t_connection_context>::set_handler(levin_comm
 }
 //------------------------------------------------------------------------------------------
 template<class t_connection_context>
+int async_protocol_handler_config<t_connection_context>::notify(int command, const epee::span<const uint8_t> in_buff, boost::uuids::uuid connection_id)
+{
+  async_protocol_handler<t_connection_context>* aph;
+  int r = find_and_lock_connection(connection_id, aph);
+  return LEVIN_OK == r ? aph->notify(command, in_buff) : r;
+}
+//------------------------------------------------------------------------------------------
+template<class t_connection_context>
 int async_protocol_handler_config<t_connection_context>::send(byte_slice message, const boost::uuids::uuid& connection_id)
 {
   async_protocol_handler<t_connection_context>* aph;
diff --git a/contrib/epee/include/storages/levin_abstract_invoke2.h b/contrib/epee/include/storages/levin_abstract_invoke2.h
index 383d67cc2..802e16c1b 100644
--- a/contrib/epee/include/storages/levin_abstract_invoke2.h
+++ b/contrib/epee/include/storages/levin_abstract_invoke2.h
@@ -37,14 +37,21 @@
 #undef MONERO_DEFAULT_LOG_CATEGORY
 #define MONERO_DEFAULT_LOG_CATEGORY "net"
 
-template<typename context_t>
-void on_levin_traffic(const context_t &context, bool initiator, bool sent, bool error, size_t bytes, const char *category);
-
-template<typename context_t>
-void on_levin_traffic(const context_t &context, bool initiator, bool sent, bool error, size_t bytes, int command);
-
 namespace
 {
+  template<typename context_t>
+  void on_levin_traffic(const context_t &context, bool initiator, bool sent, bool error, size_t bytes, const char *category)
+  {
+    MCINFO("net.p2p.traffic", context << bytes << " bytes " << (sent ? "sent" : "received") << (error ? "/corrupt" : "")
+        << " for category " << category << " initiated by " << (initiator ? "us" : "peer"));
+  }
+  template<typename context_t>
+  void on_levin_traffic(const context_t &context, bool initiator, bool sent, bool error, size_t bytes, int command)
+  {
+    char buf[32];
+    snprintf(buf, sizeof(buf),  "command-%u", command);
+    return on_levin_traffic(context, initiator, sent, error, bytes, buf);
+  }
   static const constexpr epee::serialization::portable_storage::limits_t default_levin_limits = {
     8192, // objects
     16384, // fields
@@ -110,11 +117,12 @@ namespace epee
       const boost::uuids::uuid &conn_id = context.m_connection_id;
       typename serialization::portable_storage stg;
       out_struct.store(stg);
-      levin::message_writer to_send{16 * 1024};
+      byte_slice buff_to_send;
       std::string buff_to_recv;
-      stg.store_to_binary(to_send.buffer);
+      stg.store_to_binary(buff_to_send, 16 * 1024);
 
-      int res = transport.invoke(command, std::move(to_send), buff_to_recv, conn_id);
+      on_levin_traffic(context, true, true, false, buff_to_send.size(), command);
+      int res = transport.invoke(command, boost::string_ref{reinterpret_cast<const char*>(buff_to_send.data()), buff_to_send.size()}, buff_to_recv, conn_id);
       if( res <=0 )
       {
         LOG_PRINT_L1("Failed to invoke command " << command << " return code " << res);
@@ -137,9 +145,10 @@ namespace epee
       const boost::uuids::uuid &conn_id = context.m_connection_id;
       typename serialization::portable_storage stg;
       const_cast<t_arg&>(out_struct).store(stg);//TODO: add true const support to searilzation
-      levin::message_writer to_send{16 * 1024};
-      stg.store_to_binary(to_send.buffer);
-      int res = transport.invoke_async(command, std::move(to_send), conn_id, [cb, command](int code, const epee::span<const uint8_t> buff, typename t_transport::connection_context& context)->bool
+      byte_slice buff_to_send;
+      stg.store_to_binary(buff_to_send, 16 * 1024);
+      on_levin_traffic(context, true, true, false, buff_to_send.size(), command);
+      int res = transport.invoke_async(command, epee::to_span(buff_to_send), conn_id, [cb, command](int code, const epee::span<const uint8_t> buff, typename t_transport::connection_context& context)->bool
       {
         t_result result_struct = AUTO_VAL_INIT(result_struct);
         if( code <=0 )
@@ -183,10 +192,11 @@ namespace epee
       const boost::uuids::uuid &conn_id = context.m_connection_id;
       serialization::portable_storage stg;
       out_struct.store(stg);
-      levin::message_writer to_send;
-      stg.store_to_binary(to_send.buffer);
+      byte_slice buff_to_send;
+      stg.store_to_binary(buff_to_send);
 
-      int res = transport.send(to_send.finalize_notify(command), conn_id);
+      on_levin_traffic(context, true, true, false, buff_to_send.size(), command);
+      int res = transport.notify(command, epee::to_span(buff_to_send), conn_id);
       if(res <=0 )
       {
         MERROR("Failed to notify command " << command << " return code " << res);
@@ -197,7 +207,7 @@ namespace epee
     //----------------------------------------------------------------------------------------------------
     //----------------------------------------------------------------------------------------------------
     template<class t_owner, class t_in_type, class t_out_type, class t_context, class callback_t>
-    int buff_to_t_adapter(int command, const epee::span<const uint8_t> in_buff, byte_stream& buff_out, callback_t cb, t_context& context )
+    int buff_to_t_adapter(int command, const epee::span<const uint8_t> in_buff, byte_slice& buff_out, callback_t cb, t_context& context )
     {
       serialization::portable_storage strg;
       if(!strg.load_from_binary(in_buff, &default_levin_limits))
@@ -220,11 +230,12 @@ namespace epee
       serialization::portable_storage strg_out;
       static_cast<t_out_type&>(out_struct).store(strg_out);
 
-      if(!strg_out.store_to_binary(buff_out))
+      if(!strg_out.store_to_binary(buff_out, 32 * 1024))
       {
         LOG_ERROR("Failed to store_to_binary in command" << command);
         return -1;
       }
+      on_levin_traffic(context, false, true, false, buff_out.size(), command);
 
       return res;
     }
@@ -251,7 +262,7 @@ namespace epee
     }
 
 #define CHAIN_LEVIN_INVOKE_MAP2(context_type) \
-  int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_stream& buff_out, context_type& context) \
+  int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_slice& buff_out, context_type& context) \
   { \
   bool handled = false; \
   return handle_invoke_map(false, command, in_buff, buff_out, context, handled); \
@@ -260,13 +271,13 @@ namespace epee
 #define CHAIN_LEVIN_NOTIFY_MAP2(context_type) \
   int notify(int command, const epee::span<const uint8_t> in_buff, context_type& context) \
   { \
-    bool handled = false; epee::byte_stream fake_str; \
-    return handle_invoke_map(true, command, in_buff, fake_str, context, handled); \
+  bool handled = false; epee::byte_slice fake_str; \
+  return handle_invoke_map(true, command, in_buff, fake_str, context, handled); \
   } 
 
 
 #define CHAIN_LEVIN_INVOKE_MAP() \
-  int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_stream& buff_out, epee::net_utils::connection_context_base& context) \
+  int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_slice& buff_out, epee::net_utils::connection_context_base& context) \
   { \
   bool handled = false; \
   return handle_invoke_map(false, command, in_buff, buff_out, context, handled); \
@@ -286,7 +297,7 @@ namespace epee
   } 
 
 #define BEGIN_INVOKE_MAP2(owner_type) \
-  template <class t_context> int handle_invoke_map(bool is_notify, int command, const epee::span<const uint8_t> in_buff, epee::byte_stream& buff_out, t_context& context, bool& handled) \
+  template <class t_context> int handle_invoke_map(bool is_notify, int command, const epee::span<const uint8_t> in_buff, epee::byte_slice& buff_out, t_context& context, bool& handled) \
   { \
   try { \
   typedef owner_type internal_owner_type_name;
diff --git a/contrib/epee/include/storages/portable_storage.h b/contrib/epee/include/storages/portable_storage.h
index 655a2eb12..c5d0c48ee 100644
--- a/contrib/epee/include/storages/portable_storage.h
+++ b/contrib/epee/include/storages/portable_storage.h
@@ -34,7 +34,6 @@
 namespace epee
 {
   class byte_slice;
-  class byte_stream;
   namespace serialization
   {
     /************************************************************************/
@@ -84,13 +83,8 @@ namespace epee
 
       //-------------------------------------------------------------------------------
       bool		store_to_binary(byte_slice& target, std::size_t initial_buffer_size = 8192);
-      bool		store_to_binary(byte_stream& ss);
-      bool		load_from_binary(const epee::span<const uint8_t> target, const limits_t *limits = nullptr);
-      bool		load_from_binary(const std::string& target, const limits_t *limits = nullptr)
-      {
-        return load_from_binary(epee::strspan<uint8_t>(target), limits);
-      }
-
+      bool		load_from_binary(const epee::span<const uint8_t> target, const limits_t *limits = NULL);
+      bool		load_from_binary(const std::string& target, const limits_t *limits = NULL);
       template<class trace_policy>
       bool		  dump_as_xml(std::string& targetObj, const std::string& root_name = "");
       bool		  dump_as_json(std::string& targetObj, size_t indent = 0, bool insert_newlines = true);
diff --git a/contrib/epee/include/storages/portable_storage_template_helper.h b/contrib/epee/include/storages/portable_storage_template_helper.h
index 7f6596f36..00ad15e9d 100644
--- a/contrib/epee/include/storages/portable_storage_template_helper.h
+++ b/contrib/epee/include/storages/portable_storage_template_helper.h
@@ -36,8 +36,6 @@
 
 namespace epee
 {
-  class byte_stream;
-
   namespace serialization
   {
     //-----------------------------------------------------------------------------------------------------------
@@ -129,14 +127,5 @@ namespace epee
       store_t_to_binary(str_in, binary_buff, initial_buffer_size);
       return binary_buff;
     }
-    //-----------------------------------------------------------------------------------------------------------
-    template<class t_struct>
-    bool store_t_to_binary(t_struct& str_in, byte_stream& binary_buff)
-    {
-      portable_storage ps;
-      str_in.store(ps);
-      return ps.store_to_binary(binary_buff);
-    }
-
   }
 }
diff --git a/contrib/epee/src/levin_base.cpp b/contrib/epee/src/levin_base.cpp
index 7c5cd5a78..5ec86b3d6 100644
--- a/contrib/epee/src/levin_base.cpp
+++ b/contrib/epee/src/levin_base.cpp
@@ -34,25 +34,6 @@ namespace epee
 {
 namespace levin
 {
-  message_writer::message_writer(const std::size_t reserve)
-    : buffer()
-  {
-    buffer.reserve(reserve);
-    buffer.put_n(0, sizeof(header));
-  }
-
-  byte_slice message_writer::finalize(const uint32_t command, const uint32_t flags, const uint32_t return_code, const bool expect_response)
-  {
-    if (buffer.size() < sizeof(header))
-      throw std::runtime_error{"levin_writer::finalize already called"};
-
-    header head = make_header(command, payload_size(), flags, expect_response);
-    head.m_return_code = SWAP32LE(return_code);
-
-    std::memcpy(buffer.tellp() - buffer.size(), std::addressof(head), sizeof(head));
-    return byte_slice{std::move(buffer)};
-  }
-
   bucket_head2 make_header(uint32_t command, uint64_t msg_size, uint32_t flags, bool expect_response) noexcept
   {
     bucket_head2 head = {0};
@@ -66,6 +47,12 @@ namespace levin
     return head;
   }
 
+  byte_slice make_notify(int command, epee::span<const std::uint8_t> payload)
+  {
+    const bucket_head2 head = make_header(command, payload.size(), LEVIN_PACKET_REQUEST, false);
+    return byte_slice{epee::as_byte_span(head), payload};
+  }
+
   byte_slice make_noise_notify(const std::size_t noise_bytes)
   {
     static constexpr const std::uint32_t flags =
@@ -81,40 +68,46 @@ namespace levin
     return byte_slice{std::move(buffer)};
   }
 
-  byte_slice make_fragmented_notify(const std::size_t noise_size, const int command, message_writer message)
+  byte_slice make_fragmented_notify(const byte_slice& noise_message, int command, epee::span<const std::uint8_t> payload)
   {
+    const size_t noise_size = noise_message.size();
     if (noise_size < sizeof(bucket_head2) * 2)
       return nullptr;
 
-    if (message.buffer.size() <= noise_size)
+    if (payload.size() <= noise_size - sizeof(bucket_head2))
     {
       /* The entire message can be sent at once, and the levin binary parser
          will ignore extra bytes. So just pad with zeroes and otherwise send
          a "normal", not fragmented message. */
+      const size_t padding = noise_size - sizeof(bucket_head2) - payload.size();
+      const span<const uint8_t> padding_bytes{noise_message.end() - padding, padding};
 
-      message.buffer.put_n(0, noise_size - message.buffer.size());
-      return message.finalize_notify(command);
+      const bucket_head2 head = make_header(command, noise_size - sizeof(bucket_head2), LEVIN_PACKET_REQUEST, false);
+      return byte_slice{as_byte_span(head), payload, padding_bytes};
     }
 
     // fragment message
-    const byte_slice payload_bytes = message.finalize_notify(command);
-    span<const std::uint8_t> payload = to_span(payload_bytes);
-
     const size_t payload_space = noise_size - sizeof(bucket_head2);
     const size_t expected_fragments = ((payload.size() - 2) / payload_space) + 1;
 
-    byte_stream buffer{};
-    buffer.reserve(expected_fragments * noise_size);
+    std::string buffer{};
+    buffer.reserve((expected_fragments + 1) * noise_size); // +1 here overselects for internal bucket_head2 value
 
-    bucket_head2 head = make_header(0, payload_space, LEVIN_PACKET_BEGIN, false);
-    buffer.write(as_byte_span(head));
+    bucket_head2 head = make_header(0, noise_size - sizeof(bucket_head2), LEVIN_PACKET_BEGIN, false);
+    buffer.append(reinterpret_cast<const char*>(&head), sizeof(head));
 
-    // internal levin header is in payload already
+    head.m_command = command;
+    head.m_flags = LEVIN_PACKET_REQUEST;
+    head.m_cb = payload.size();
+    buffer.append(reinterpret_cast<const char*>(&head), sizeof(head));
 
-    size_t copy_size = payload.remove_prefix(payload_space);
-    buffer.write(payload.data() - copy_size, copy_size);
+    size_t copy_size = payload.remove_prefix(payload_space - sizeof(bucket_head2));
+    buffer.append(reinterpret_cast<const char*>(payload.data()) - copy_size, copy_size);
 
+    head.m_command = 0;
     head.m_flags = 0;
+    head.m_cb = noise_size - sizeof(bucket_head2);
+
     while (!payload.empty())
     {
       copy_size = payload.remove_prefix(payload_space);
@@ -122,12 +115,12 @@ namespace levin
       if (payload.empty())
         head.m_flags = LEVIN_PACKET_END;
 
-      buffer.write(as_byte_span(head));
-      buffer.write(payload.data() - copy_size, copy_size);
+      buffer.append(reinterpret_cast<const char*>(&head), sizeof(head));
+      buffer.append(reinterpret_cast<const char*>(payload.data()) - copy_size, copy_size);
     }
 
     const size_t padding = noise_size - copy_size - sizeof(bucket_head2);
-    buffer.put_n(0, padding);
+    buffer.append(reinterpret_cast<const char*>(noise_message.end()) - padding, padding);
 
     return byte_slice{std::move(buffer)};
   }
diff --git a/contrib/epee/src/portable_storage.cpp b/contrib/epee/src/portable_storage.cpp
index b922cc9e3..c3c9ccc02 100644
--- a/contrib/epee/src/portable_storage.cpp
+++ b/contrib/epee/src/portable_storage.cpp
@@ -48,23 +48,15 @@ namespace serialization
     TRY_ENTRY();
     byte_stream ss;
     ss.reserve(initial_buffer_size);
-    store_to_binary(ss);
-    target = epee::byte_slice{std::move(ss)};
-    return true;
-    CATCH_ENTRY("portable_storage::store_to_binary", false);
-  }
-
-  bool portable_storage::store_to_binary(byte_stream& ss)
-  {
-    TRY_ENTRY();
     storage_block_header sbh{};
     sbh.m_signature_a = SWAP32LE(PORTABLE_STORAGE_SIGNATUREA);
     sbh.m_signature_b = SWAP32LE(PORTABLE_STORAGE_SIGNATUREB);
     sbh.m_ver = PORTABLE_STORAGE_FORMAT_VER;
     ss.write(epee::as_byte_span(sbh));
     pack_entry_to_buff(ss, m_root);
+    target = epee::byte_slice{std::move(ss)};
     return true;
-    CATCH_ENTRY("portable_storage::store_to_binary", false);
+    CATCH_ENTRY("portable_storage::store_to_binary", false)
   }
 
     bool portable_storage::dump_as_json(std::string& buff, size_t indent, bool insert_newlines)
@@ -84,6 +76,11 @@ namespace serialization
       CATCH_ENTRY("portable_storage::load_from_json", false)
     }
 
+    bool portable_storage::load_from_binary(const std::string& target, const limits_t *limits)
+    {
+         return load_from_binary(epee::strspan<uint8_t>(target), limits);
+    }
+
     bool portable_storage::load_from_binary(const epee::span<const uint8_t> source, const limits_t *limits)
     {
       m_root.m_entries.clear();
diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index a3d695b85..cdad39a2c 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -57,7 +57,6 @@
 #include "common/notify.h"
 #include "common/varint.h"
 #include "common/pruning.h"
-#include "time_helper.h"
 
 #undef MONERO_DEFAULT_LOG_CATEGORY
 #define MONERO_DEFAULT_LOG_CATEGORY "blockchain"
diff --git a/src/cryptonote_protocol/cryptonote_protocol_handler.h b/src/cryptonote_protocol/cryptonote_protocol_handler.h
index 80dd2bc39..28530f3e7 100644
--- a/src/cryptonote_protocol/cryptonote_protocol_handler.h
+++ b/src/cryptonote_protocol/cryptonote_protocol_handler.h
@@ -46,8 +46,6 @@
 #include "block_queue.h"
 #include "common/perf_timer.h"
 #include "cryptonote_basic/connection_context.h"
-#include "net/levin_base.h"
-#include "p2p/net_node_common.h"
 #include <boost/circular_buffer.hpp>
 
 PUSH_WARNINGS
@@ -197,11 +195,10 @@ namespace cryptonote
       bool post_notify(typename t_parameter::request& arg, cryptonote_connection_context& context)
       {
         LOG_PRINT_L2("[" << epee::net_utils::print_connection_context_short(context) << "] post " << typeid(t_parameter).name() << " -->");
-
-        epee::levin::message_writer out{256 * 1024}; // optimize for block responses
-        epee::serialization::store_t_to_binary(arg, out.buffer);
+        epee::byte_slice blob;
+        epee::serialization::store_t_to_binary(arg, blob, 256 * 1024); // optimize for block responses
         //handler_response_blocks_now(blob.size()); // XXX
-        return m_p2p->invoke_notify_to_peer(t_parameter::ID, std::move(out), context);
+        return m_p2p->invoke_notify_to_peer(t_parameter::ID, epee::to_span(blob), context);
       }
   };
 
diff --git a/src/cryptonote_protocol/cryptonote_protocol_handler.inl b/src/cryptonote_protocol/cryptonote_protocol_handler.inl
index afc81f552..69ef0970b 100644
--- a/src/cryptonote_protocol/cryptonote_protocol_handler.inl
+++ b/src/cryptonote_protocol/cryptonote_protocol_handler.inl
@@ -2713,15 +2713,15 @@ skip:
     // send fluffy ones first, we want to encourage people to run that
     if (!fluffyConnections.empty())
     {
-      epee::levin::message_writer fluffyBlob{32 * 1024};
-      epee::serialization::store_t_to_binary(fluffy_arg, fluffyBlob.buffer);
-      m_p2p->relay_notify_to_list(NOTIFY_NEW_FLUFFY_BLOCK::ID, std::move(fluffyBlob), std::move(fluffyConnections));
+      epee::byte_slice fluffyBlob;
+      epee::serialization::store_t_to_binary(fluffy_arg, fluffyBlob, 32 * 1024);
+      m_p2p->relay_notify_to_list(NOTIFY_NEW_FLUFFY_BLOCK::ID, epee::to_span(fluffyBlob), std::move(fluffyConnections));
     }
     if (!fullConnections.empty())
     {
-      epee::levin::message_writer fullBlob{128 * 1024};
-      epee::serialization::store_t_to_binary(arg, fullBlob.buffer);
-      m_p2p->relay_notify_to_list(NOTIFY_NEW_BLOCK::ID, std::move(fullBlob), std::move(fullConnections));
+      epee::byte_slice fullBlob;
+      epee::serialization::store_t_to_binary(arg, fullBlob, 128 * 1024);
+      m_p2p->relay_notify_to_list(NOTIFY_NEW_BLOCK::ID, epee::to_span(fullBlob), std::move(fullConnections));
     }
 
     return true;
diff --git a/src/cryptonote_protocol/cryptonote_protocol_handler_common.h b/src/cryptonote_protocol/cryptonote_protocol_handler_common.h
index 57b1d049c..79c2edf1d 100644
--- a/src/cryptonote_protocol/cryptonote_protocol_handler_common.h
+++ b/src/cryptonote_protocol/cryptonote_protocol_handler_common.h
@@ -30,8 +30,8 @@
 
 #pragma once
 
+#include "p2p/net_node_common.h"
 #include "cryptonote_protocol/cryptonote_protocol_defs.h"
-#include "cryptonote_protocol/enums.h"
 #include "cryptonote_basic/connection_context.h"
 namespace cryptonote
 {
diff --git a/src/cryptonote_protocol/levin_notify.cpp b/src/cryptonote_protocol/levin_notify.cpp
index 0b065c3c3..1e9f3e399 100644
--- a/src/cryptonote_protocol/levin_notify.cpp
+++ b/src/cryptonote_protocol/levin_notify.cpp
@@ -159,7 +159,7 @@ namespace levin
       return get_out_connections(p2p, get_blockchain_height(p2p, core));
     }
 
-    epee::levin::message_writer make_tx_message(std::vector<blobdata>&& txs, const bool pad, const bool fluff)
+    epee::byte_slice make_tx_payload(std::vector<blobdata>&& txs, const bool pad, const bool fluff)
     {
       NOTIFY_NEW_TRANSACTIONS::request request{};
       request.txs = std::move(txs);
@@ -193,17 +193,21 @@ namespace levin
         // if the size of _ moved enough, we might lose byte in size encoding, we don't care
       }
 
-      epee::levin::message_writer out;
-      if (!epee::serialization::store_t_to_binary(request, out.buffer))
+      epee::byte_slice fullBlob;
+      if (!epee::serialization::store_t_to_binary(request, fullBlob))
         throw std::runtime_error{"Failed to serialize to epee binary format"};
 
-      return out;
+      return fullBlob;
     }
 
     bool make_payload_send_txs(connections& p2p, std::vector<blobdata>&& txs, const boost::uuids::uuid& destination, const bool pad, const bool fluff)
     {
-      epee::byte_slice blob = make_tx_message(std::move(txs), pad, fluff).finalize_notify(NOTIFY_NEW_TRANSACTIONS::ID);
-      return p2p.send(std::move(blob), destination);
+      const epee::byte_slice blob = make_tx_payload(std::move(txs), pad, fluff);
+      p2p.for_connection(destination, [&blob](detail::p2p_context& context) {
+        on_levin_traffic(context, true, true, false, blob.size(), NOTIFY_NEW_TRANSACTIONS::ID);
+        return true;
+      });
+      return p2p.notify(NOTIFY_NEW_TRANSACTIONS::ID, epee::to_span(blob), destination);
     }
 
     /* The current design uses `asio::strand`s. The documentation isn't as clear
@@ -649,6 +653,10 @@ namespace levin
           else
             message = zone_->noise.clone();
 
+          zone_->p2p->for_connection(channel.connection, [&](detail::p2p_context& context) {
+            on_levin_traffic(context, true, true, false, message.size(), "noise");
+            return true;
+          });
           if (zone_->p2p->send(std::move(message), channel.connection))
           {
             if (!channel.queue.empty() && channel.active.empty())
@@ -808,8 +816,9 @@ namespace levin
 
       // Padding is not useful when using noise mode. Send as stem so receiver
       // forwards in Dandelion++ mode.
+      const epee::byte_slice payload = make_tx_payload(std::move(txs), false, false);
       epee::byte_slice message = epee::levin::make_fragmented_notify(
-        zone_->noise.size(), NOTIFY_NEW_TRANSACTIONS::ID, make_tx_message(std::move(txs), false, false)
+        zone_->noise, NOTIFY_NEW_TRANSACTIONS::ID, epee::to_span(payload)
       );
       if (CRYPTONOTE_MAX_FRAGMENTS * zone_->noise.size() < message.size())
       {
diff --git a/src/p2p/net_node.h b/src/p2p/net_node.h
index f2888674b..db931122e 100644
--- a/src/p2p/net_node.h
+++ b/src/p2p/net_node.h
@@ -344,9 +344,10 @@ namespace nodetool
     virtual void on_connection_close(p2p_connection_context& context);
     virtual void callback(p2p_connection_context& context);
     //----------------- i_p2p_endpoint -------------------------------------------------------------
-    virtual bool relay_notify_to_list(int command, epee::levin::message_writer message, std::vector<std::pair<epee::net_utils::zone, boost::uuids::uuid>> connections) final;
+    virtual bool relay_notify_to_list(int command, const epee::span<const uint8_t> data_buff, std::vector<std::pair<epee::net_utils::zone, boost::uuids::uuid>> connections);
     virtual epee::net_utils::zone send_txs(std::vector<cryptonote::blobdata> txs, const epee::net_utils::zone origin, const boost::uuids::uuid& source, cryptonote::relay_method tx_relay);
-    virtual bool invoke_notify_to_peer(int command, epee::levin::message_writer message, const epee::net_utils::connection_context_base& context) final;
+    virtual bool invoke_command_to_peer(int command, const epee::span<const uint8_t> req_buff, std::string& resp_buff, const epee::net_utils::connection_context_base& context);
+    virtual bool invoke_notify_to_peer(int command, const epee::span<const uint8_t> req_buff, const epee::net_utils::connection_context_base& context);
     virtual bool drop_connection(const epee::net_utils::connection_context_base& context);
     virtual void request_callback(const epee::net_utils::connection_context_base& context);
     virtual void for_each_connection(std::function<bool(typename t_payload_net_handler::connection_context&, peerid_type, uint32_t)> f);
diff --git a/src/p2p/net_node.inl b/src/p2p/net_node.inl
index e1d6d1e10..ea69760c7 100644
--- a/src/p2p/net_node.inl
+++ b/src/p2p/net_node.inl
@@ -2175,9 +2175,8 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
-  bool node_server<t_payload_net_handler>::relay_notify_to_list(int command, epee::levin::message_writer data_buff, std::vector<std::pair<epee::net_utils::zone, boost::uuids::uuid>> connections)
+  bool node_server<t_payload_net_handler>::relay_notify_to_list(int command, const epee::span<const uint8_t> data_buff, std::vector<std::pair<epee::net_utils::zone, boost::uuids::uuid>> connections)
   {
-    epee::byte_slice message = data_buff.finalize_notify(command);
     std::sort(connections.begin(), connections.end());
     auto zone = m_network_zones.begin();
     for(const auto& c_id: connections)
@@ -2195,7 +2194,7 @@ namespace nodetool
         ++zone;
       }
       if (zone->first == c_id.first)
-        zone->second.m_net_server.get_config_object().send(message.clone(), c_id.second);
+        zone->second.m_net_server.get_config_object().notify(command, data_buff, c_id.second);
     }
     return true;
   }
@@ -2262,13 +2261,24 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
-  bool node_server<t_payload_net_handler>::invoke_notify_to_peer(const int command, epee::levin::message_writer message, const epee::net_utils::connection_context_base& context)
+  bool node_server<t_payload_net_handler>::invoke_notify_to_peer(int command, const epee::span<const uint8_t> req_buff, const epee::net_utils::connection_context_base& context)
   {
     if(is_filtered_command(context.m_remote_address, command))
       return false;
 
     network_zone& zone = m_network_zones.at(context.m_remote_address.get_zone());
-    int res = zone.m_net_server.get_config_object().send(message.finalize_notify(command), context.m_connection_id);
+    int res = zone.m_net_server.get_config_object().notify(command, req_buff, context.m_connection_id);
+    return res > 0;
+  }
+  //-----------------------------------------------------------------------------------
+  template<class t_payload_net_handler>
+  bool node_server<t_payload_net_handler>::invoke_command_to_peer(int command, const epee::span<const uint8_t> req_buff, std::string& resp_buff, const epee::net_utils::connection_context_base& context)
+  {
+    if(is_filtered_command(context.m_remote_address, command))
+      return false;
+
+    network_zone& zone = m_network_zones.at(context.m_remote_address.get_zone());
+    int res = zone.m_net_server.get_config_object().invoke(command, req_buff, resp_buff, context.m_connection_id);
     return res > 0;
   }
   //-----------------------------------------------------------------------------------
diff --git a/src/p2p/net_node_common.h b/src/p2p/net_node_common.h
index 92b7596ae..0da758ad4 100644
--- a/src/p2p/net_node_common.h
+++ b/src/p2p/net_node_common.h
@@ -40,8 +40,6 @@
 #include "net/net_utils_base.h"
 #include "p2p_protocol_defs.h"
 
-namespace epee { namespace levin { class message_writer; } }
-
 namespace nodetool
 {
 
@@ -51,9 +49,10 @@ namespace nodetool
   template<class t_connection_context>
   struct i_p2p_endpoint
   {
-    virtual bool relay_notify_to_list(int command, epee::levin::message_writer message, std::vector<std::pair<epee::net_utils::zone, boost::uuids::uuid>> connections)=0;
+    virtual bool relay_notify_to_list(int command, const epee::span<const uint8_t> data_buff, std::vector<std::pair<epee::net_utils::zone, boost::uuids::uuid>> connections)=0;
     virtual epee::net_utils::zone send_txs(std::vector<cryptonote::blobdata> txs, const epee::net_utils::zone origin, const boost::uuids::uuid& source, cryptonote::relay_method tx_relay)=0;
-    virtual bool invoke_notify_to_peer(int command, epee::levin::message_writer message, const epee::net_utils::connection_context_base& context)=0;
+    virtual bool invoke_command_to_peer(int command, const epee::span<const uint8_t> req_buff, std::string& resp_buff, const epee::net_utils::connection_context_base& context)=0;
+    virtual bool invoke_notify_to_peer(int command, const epee::span<const uint8_t> req_buff, const epee::net_utils::connection_context_base& context)=0;
     virtual bool drop_connection(const epee::net_utils::connection_context_base& context)=0;
     virtual void request_callback(const epee::net_utils::connection_context_base& context)=0;
     virtual uint64_t get_public_connections_count()=0;
@@ -72,7 +71,7 @@ namespace nodetool
   template<class t_connection_context>
   struct p2p_endpoint_stub: public i_p2p_endpoint<t_connection_context>
   {
-    virtual bool relay_notify_to_list(int command, epee::levin::message_writer message, std::vector<std::pair<epee::net_utils::zone, boost::uuids::uuid>> connections)
+    virtual bool relay_notify_to_list(int command, const epee::span<const uint8_t> data_buff, std::vector<std::pair<epee::net_utils::zone, boost::uuids::uuid>> connections)
     {
       return false;
     }
@@ -80,7 +79,11 @@ namespace nodetool
     {
       return epee::net_utils::zone::invalid;
     }
-    virtual bool invoke_notify_to_peer(int command, epee::levin::message_writer message, const epee::net_utils::connection_context_base& context)
+    virtual bool invoke_command_to_peer(int command, const epee::span<const uint8_t> req_buff, std::string& resp_buff, const epee::net_utils::connection_context_base& context)
+    {
+      return false;
+    }
+    virtual bool invoke_notify_to_peer(int command, const epee::span<const uint8_t> req_buff, const epee::net_utils::connection_context_base& context)
     {
       return true;
     }
diff --git a/tests/fuzz/levin.cpp b/tests/fuzz/levin.cpp
index 209a75221..78b7b6863 100644
--- a/tests/fuzz/levin.cpp
+++ b/tests/fuzz/levin.cpp
@@ -68,13 +68,13 @@ namespace
     {
     }
 
-    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_stream& buff_out, test_levin_connection_context& context)
+    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_slice& buff_out, test_levin_connection_context& context)
     {
       m_invoke_counter.inc();
       boost::unique_lock<boost::mutex> lock(m_mutex);
       m_last_command = command;
       m_last_in_buf = std::string((const char*)in_buff.data(), in_buff.size());
-      buff_out.write(epee::to_span(m_invoke_out_buf));
+      buff_out = m_invoke_out_buf.clone();
       return m_return_code;
     }
 
diff --git a/tests/net_load_tests/net_load_tests.h b/tests/net_load_tests/net_load_tests.h
index 59eef7bd1..baab07d31 100644
--- a/tests/net_load_tests/net_load_tests.h
+++ b/tests/net_load_tests/net_load_tests.h
@@ -67,7 +67,7 @@ namespace net_load_tests
     {
     }
 
-    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_stream& buff_out, test_connection_context& context)
+    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_slice& buff_out, test_connection_context& context)
     {
       //m_invoke_counter.inc();
       //std::unique_lock<std::mutex> lock(m_mutex);
diff --git a/tests/unit_tests/epee_boosted_tcp_server.cpp b/tests/unit_tests/epee_boosted_tcp_server.cpp
index 84fc0a29b..457c05c15 100644
--- a/tests/unit_tests/epee_boosted_tcp_server.cpp
+++ b/tests/unit_tests/epee_boosted_tcp_server.cpp
@@ -153,7 +153,7 @@ TEST(test_epee_connection, test_lifetime)
       delay(delay),
       on_connection_close_f(on_connection_close_f)
     {}
-    virtual int invoke(int, const epee::span<const uint8_t>, epee::byte_stream&, context_t&) override { epee::misc_utils::sleep_no_w(delay); return {}; }
+    virtual int invoke(int, const epee::span<const uint8_t>, epee::byte_slice&, context_t&) override { epee::misc_utils::sleep_no_w(delay); return {}; }
     virtual int notify(int, const epee::span<const uint8_t>, context_t&) override { return {}; }
     virtual void callback(context_t&) override {}
     virtual void on_connection_new(context_t&) override {}
@@ -282,7 +282,7 @@ TEST(test_epee_connection, test_lifetime)
     for (auto i = 0; i < N; ++i) {
       tag = create_connection();
       ASSERT_TRUE(shared_state->get_connections_count() == 1);
-      success = shared_state->invoke_async(1, epee::levin::message_writer{}, tag, [](int, const epee::span<const uint8_t>, context_t&){}, TIMEOUT);
+      success = shared_state->invoke_async(1, {}, tag, [](int, const epee::span<const uint8_t>, context_t&){}, TIMEOUT);
       ASSERT_TRUE(success);
       while (shared_state->sock_count == 1) {
         success = shared_state->foreach_connection([&shared_state, &tag](context_t&){
diff --git a/tests/unit_tests/epee_levin_protocol_handler_async.cpp b/tests/unit_tests/epee_levin_protocol_handler_async.cpp
index d9de99b8b..a499fa608 100644
--- a/tests/unit_tests/epee_levin_protocol_handler_async.cpp
+++ b/tests/unit_tests/epee_levin_protocol_handler_async.cpp
@@ -59,13 +59,13 @@ namespace
     {
     }
 
-    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_stream& buff_out, test_levin_connection_context& context)
+    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_slice& buff_out, test_levin_connection_context& context)
     {
       m_invoke_counter.inc();
       boost::unique_lock<boost::mutex> lock(m_mutex);
       m_last_command = command;
       m_last_in_buf = std::string((const char*)in_buff.data(), in_buff.size());
-      buff_out.write(epee::to_span(m_invoke_out_buf));
+      buff_out = m_invoke_out_buf.clone();
       return m_return_code;
     }
 
@@ -434,11 +434,8 @@ TEST_F(positive_test_connection_to_levin_protocol_handler_calls, handler_process
   const int expected_command = 4673261;
   const std::string in_data(256, 'e');
 
-  epee::levin::message_writer message{};
-  message.buffer.write(epee::to_span(in_data));
-
   const epee::byte_slice noise = epee::levin::make_noise_notify(1024);
-  const epee::byte_slice notify = message.finalize_notify(expected_command);
+  const epee::byte_slice notify = epee::levin::make_notify(expected_command, epee::strspan<std::uint8_t>(in_data));
 
   test_connection_ptr conn = create_connection();
 
@@ -471,16 +468,11 @@ TEST_F(positive_test_connection_to_levin_protocol_handler_calls, handler_process
   const int expected_command = 4673261;
   const int expected_fragmented_command = 46732;
   const std::string in_data(256, 'e');
-
-  epee::levin::message_writer message{};
-  message.buffer.write(epee::to_span(in_data));
-
-  epee::levin::message_writer in_fragmented_data;
-  in_fragmented_data.buffer.put_n('c', 1024 * 4);
+  std::string in_fragmented_data(1024 * 4, 'c');
 
   const epee::byte_slice noise = epee::levin::make_noise_notify(1024);
-  const epee::byte_slice notify = message.finalize_notify(expected_command);
-  epee::byte_slice fragmented = epee::levin::make_fragmented_notify(noise.size(), expected_fragmented_command, std::move(in_fragmented_data));
+  const epee::byte_slice notify = epee::levin::make_notify(expected_command, epee::strspan<std::uint8_t>(in_data));
+  epee::byte_slice fragmented = epee::levin::make_fragmented_notify(noise, expected_fragmented_command, epee::strspan<std::uint8_t>(in_fragmented_data));
 
   EXPECT_EQ(5u, fragmented.size() / 1024);
   EXPECT_EQ(0u, fragmented.size() % 1024);
@@ -505,13 +497,11 @@ TEST_F(positive_test_connection_to_levin_protocol_handler_calls, handler_process
     ASSERT_TRUE(conn->m_protocol_handler.handle_recv(next.data(), next.size()));
   }
 
-  std::string compare_buffer(1024 * 4, 'c');
-  compare_buffer.resize(((1024 - sizeof(epee::levin::bucket_head2)) * 5) - sizeof(epee::levin::bucket_head2)); // add padding zeroes
-
+  in_fragmented_data.resize(((1024 - sizeof(epee::levin::bucket_head2)) * 5) - sizeof(epee::levin::bucket_head2)); // add padding zeroes
   ASSERT_EQ(4u, m_commands_handler.notify_counter());
   ASSERT_EQ(0u, m_commands_handler.invoke_counter());
   ASSERT_EQ(expected_fragmented_command, m_commands_handler.last_command());
-  ASSERT_EQ(compare_buffer, m_commands_handler.last_in_buf());
+  ASSERT_EQ(in_fragmented_data, m_commands_handler.last_in_buf());
   ASSERT_EQ(0u, conn->send_counter());
   ASSERT_TRUE(conn->last_send_data().empty());
 
diff --git a/tests/unit_tests/levin.cpp b/tests/unit_tests/levin.cpp
index 30d6f8133..eee9e224d 100644
--- a/tests/unit_tests/levin.cpp
+++ b/tests/unit_tests/levin.cpp
@@ -245,9 +245,9 @@ namespace
             return out;
         }
 
-        virtual int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_stream& buff_out, cryptonote::levin::detail::p2p_context& context) override final
+        virtual int invoke(int command, const epee::span<const uint8_t> in_buff, epee::byte_slice& buff_out, cryptonote::levin::detail::p2p_context& context) override final
         {
-            buff_out.clear();
+            buff_out = nullptr;
             invoked_.push_back(
                 {context.m_connection_id, command, std::string{reinterpret_cast<const char*>(in_buff.data()), in_buff.size()}}
             );
@@ -384,50 +384,21 @@ TEST(make_header, expect_return)
     EXPECT_EQ(0u, header1.m_flags);
 }
 
-TEST(message_writer, invoke_with_empty_payload)
+TEST(make_notify, empty_payload)
 {
-    const epee::byte_slice message = epee::levin::message_writer{}.finalize_invoke(443);
-    const epee::levin::bucket_head2 header =
-        epee::levin::make_header(443, 0, LEVIN_PACKET_REQUEST, true);
-    ASSERT_EQ(sizeof(header), message.size());
-    EXPECT_TRUE(std::memcmp(std::addressof(header), message.data(), sizeof(header)) == 0);
-}
-
-TEST(message_writer, invoke_with_payload)
-{
-    std::string bytes(100, 'a');
-    std::generate(bytes.begin(), bytes.end(), crypto::random_device{});
-
-    epee::levin::message_writer writer{};
-    writer.buffer.write(epee::to_span(bytes));
-
-    const epee::byte_slice message = writer.finalize_invoke(443);
-    const epee::levin::bucket_head2 header =
-        epee::levin::make_header(443, bytes.size(), LEVIN_PACKET_REQUEST, true);
-
-    ASSERT_EQ(sizeof(header) + bytes.size(), message.size());
-    EXPECT_TRUE(std::memcmp(std::addressof(header), message.data(), sizeof(header)) == 0);
-    EXPECT_TRUE(std::memcmp(bytes.data(), message.data() + sizeof(header), bytes.size()) == 0);
-}
-
-TEST(message_writer, notify_with_empty_payload)
-{
-    const epee::byte_slice message = epee::levin::message_writer{}.finalize_notify(443);
+    const epee::byte_slice message = epee::levin::make_notify(443, nullptr);
     const epee::levin::bucket_head2 header =
         epee::levin::make_header(443, 0, LEVIN_PACKET_REQUEST, false);
     ASSERT_EQ(sizeof(header), message.size());
     EXPECT_TRUE(std::memcmp(std::addressof(header), message.data(), sizeof(header)) == 0);
 }
 
-TEST(message_writer, notify_with_payload)
+TEST(make_notify, with_payload)
 {
     std::string bytes(100, 'a');
     std::generate(bytes.begin(), bytes.end(), crypto::random_device{});
 
-    epee::levin::message_writer writer{};
-    writer.buffer.write(epee::to_span(bytes));
-
-    const epee::byte_slice message = writer.finalize_notify(443);
+    const epee::byte_slice message = epee::levin::make_notify(443, epee::strspan<std::uint8_t>(bytes));
     const epee::levin::bucket_head2 header =
         epee::levin::make_header(443, bytes.size(), LEVIN_PACKET_REQUEST, false);
 
@@ -436,44 +407,6 @@ TEST(message_writer, notify_with_payload)
     EXPECT_TRUE(std::memcmp(bytes.data(), message.data() + sizeof(header), bytes.size()) == 0);
 }
 
-TEST(message_writer, response_with_empty_payload)
-{
-    const epee::byte_slice message = epee::levin::message_writer{}.finalize_response(443, 1);
-    epee::levin::bucket_head2 header =
-        epee::levin::make_header(443, 0, LEVIN_PACKET_RESPONSE, false);
-    header.m_return_code = SWAP32LE(1);
-    ASSERT_EQ(sizeof(header), message.size());
-    EXPECT_TRUE(std::memcmp(std::addressof(header), message.data(), sizeof(header)) == 0);
-}
-
-TEST(message_writer, response_with_payload)
-{
-    std::string bytes(100, 'a');
-    std::generate(bytes.begin(), bytes.end(), crypto::random_device{});
-
-    epee::levin::message_writer writer{};
-    writer.buffer.write(epee::to_span(bytes));
-
-    const epee::byte_slice message = writer.finalize_response(443, 6450);
-    epee::levin::bucket_head2 header =
-        epee::levin::make_header(443, bytes.size(), LEVIN_PACKET_RESPONSE, false);
-    header.m_return_code = SWAP32LE(6450);
-
-    ASSERT_EQ(sizeof(header) + bytes.size(), message.size());
-    EXPECT_TRUE(std::memcmp(std::addressof(header), message.data(), sizeof(header)) == 0);
-    EXPECT_TRUE(std::memcmp(bytes.data(), message.data() + sizeof(header), bytes.size()) == 0);
-}
-
-TEST(message_writer, error)
-{
-    epee::levin::message_writer writer{};
-    writer.buffer.clear();
-
-    EXPECT_THROW(writer.finalize_invoke(0), std::runtime_error);
-    EXPECT_THROW(writer.finalize_notify(0), std::runtime_error);
-    EXPECT_THROW(writer.finalize_response(0, 0), std::runtime_error);
-}
-
 TEST(make_noise, invalid)
 {
     EXPECT_TRUE(epee::levin::make_noise_notify(sizeof(epee::levin::bucket_head2) - 1).empty());
@@ -495,13 +428,13 @@ TEST(make_noise, valid)
 
 TEST(make_fragment, invalid)
 {
-    EXPECT_TRUE(epee::levin::make_fragmented_notify(0, 0, epee::levin::message_writer{}).empty());
+    EXPECT_TRUE(epee::levin::make_fragmented_notify(nullptr, 0, nullptr).empty());
 }
 
 TEST(make_fragment, single)
 {
     const epee::byte_slice noise = epee::levin::make_noise_notify(1024);
-    const epee::byte_slice fragment = epee::levin::make_fragmented_notify(noise.size(), 11, epee::levin::message_writer{});
+    const epee::byte_slice fragment = epee::levin::make_fragmented_notify(noise, 11, nullptr);
     const epee::levin::bucket_head2 header =
         epee::levin::make_header(11, 1024 - sizeof(epee::levin::bucket_head2), LEVIN_PACKET_REQUEST, false);
 
@@ -516,13 +449,8 @@ TEST(make_fragment, multiple)
     std::string bytes(1024 * 3 - 150, 'a');
     std::generate(bytes.begin(), bytes.end(), crypto::random_device{});
 
-    epee::levin::message_writer message;
-    message.buffer.write(epee::to_span(bytes));
-
     const epee::byte_slice noise = epee::levin::make_noise_notify(1024);
-    epee::byte_slice fragment = epee::levin::make_fragmented_notify(noise.size(), 114, std::move(message));
-
-    EXPECT_EQ(1024 * 3, fragment.size());
+    epee::byte_slice fragment = epee::levin::make_fragmented_notify(noise, 114, epee::strspan<std::uint8_t>(bytes));
 
     epee::levin::bucket_head2 header =
         epee::levin::make_header(0, 1024 - sizeof(epee::levin::bucket_head2), LEVIN_PACKET_BEGIN, false);
@@ -569,7 +497,6 @@ TEST(make_fragment, multiple)
 
     fragment.take_slice(bytes.size());
 
-    EXPECT_EQ(18, fragment.size());
     EXPECT_EQ(18, std::count(fragment.cbegin(), fragment.cend(), 0));
 }
 
@@ -2237,31 +2164,20 @@ TEST_F(levin_notify, command_max_bytes)
 
     add_connection(true);
 
-    std::string payload(4096, 'h');
-    epee::byte_slice bytes;
-    {
-        epee::levin::message_writer dest{};
-        dest.buffer.write(epee::to_span(payload));
-        bytes = dest.finalize_notify(ping_command);
-    }
+    std::string bytes(4096, 'h');
 
-    EXPECT_EQ(1, get_connections().send(bytes.clone(), contexts_.front().get_id()));
+    EXPECT_EQ(1, get_connections().notify(ping_command, epee::strspan<std::uint8_t>(bytes), contexts_.front().get_id()));
     EXPECT_EQ(1u, contexts_.front().process_send_queue(true));
     EXPECT_EQ(1u, receiver_.notified_size());
 
     const received_message msg = receiver_.get_raw_notification();
     EXPECT_EQ(ping_command, msg.command);
     EXPECT_EQ(contexts_.front().get_id(), msg.connection);
-    EXPECT_EQ(payload, msg.payload);
+    EXPECT_EQ(bytes, msg.payload);
 
-    {
-        payload.push_back('h');
-        epee::levin::message_writer dest{};
-        dest.buffer.write(epee::to_span(payload));
-        bytes = dest.finalize_notify(ping_command);
-    }
+    bytes.push_back('e');
 
-    EXPECT_EQ(1, get_connections().send(std::move(bytes), contexts_.front().get_id()));
+    EXPECT_EQ(1, get_connections().notify(ping_command, epee::strspan<std::uint8_t>(bytes), contexts_.front().get_id()));
     EXPECT_EQ(1u, contexts_.front().process_send_queue(false));
     EXPECT_EQ(0u, receiver_.notified_size());
 }