epee: better network buffer data structure

avoids pointless allocs and memcpy

22 files changed, 325 insertions, 85 deletions

diff --git a/contrib/epee/include/net/buffer.h b/contrib/epee/include/net/buffer.h
new file mode 100644
index 000000000..56c67f6bf
--- /dev/null
+++ b/contrib/epee/include/net/buffer.h
@@ -0,0 +1,62 @@
+// Copyright (c) 2018, 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 <vector>
+#include "misc_log_ex.h"
+#include "span.h"
+
+#undef MONERO_DEFAULT_LOG_CATEGORY
+#define MONERO_DEFAULT_LOG_CATEGORY "net.buffer"
+
+//#define NET_BUFFER_LOG(x) MDEBUG(x)
+#define NET_BUFFER_LOG(x) ((void)0)
+
+namespace epee
+{
+namespace net_utils
+{
+class buffer
+{
+public:
+  buffer(size_t reserve = 0): offset(0) { storage.reserve(reserve); }
+
+  void append(const void *data, size_t sz);
+  void erase(size_t sz) { NET_BUFFER_LOG("erasing " << sz << "/" << size()); CHECK_AND_ASSERT_THROW_MES(offset + sz <= storage.size(), "erase: sz too large"); offset += sz; if (offset == storage.size()) { storage.resize(0); offset = 0; } }
+  epee::span<const uint8_t> span(size_t sz) const { CHECK_AND_ASSERT_THROW_MES(sz <= size(), "span is too large"); return epee::span<const uint8_t>(storage.data() + offset, sz); }
+  // carve must keep the data in scope till next call, other API calls (such as append, erase) can invalidate the carved buffer
+  epee::span<const uint8_t> carve(size_t sz) { CHECK_AND_ASSERT_THROW_MES(sz <= size(), "span is too large"); offset += sz; return epee::span<const uint8_t>(storage.data() + offset - sz, sz); }
+  size_t size() const { return storage.size() - offset; }
+
+private:
+  std::vector<uint8_t> storage;
+  size_t offset;
+};
+}
+}
diff --git a/contrib/epee/include/net/http_server_handlers_map2.h b/contrib/epee/include/net/http_server_handlers_map2.h
index 997c801d1..64d035df9 100644
--- a/contrib/epee/include/net/http_server_handlers_map2.h
+++ b/contrib/epee/include/net/http_server_handlers_map2.h
@@ -92,7 +92,7 @@
       handled = true; \
       uint64_t ticks = misc_utils::get_tick_count(); \
       boost::value_initialized<command_type::request> req; \
-      bool parse_res = epee::serialization::load_t_from_binary(static_cast<command_type::request&>(req), query_info.m_body); \
+      bool parse_res = epee::serialization::load_t_from_binary(static_cast<command_type::request&>(req), epee::strspan<uint8_t>(query_info.m_body)); \
       CHECK_AND_ASSERT_MES(parse_res, false, "Failed to parse bin body data, body size=" << query_info.m_body.size()); \
       uint64_t ticks1 = misc_utils::get_tick_count(); \
       boost::value_initialized<command_type::response> resp;\
diff --git a/contrib/epee/include/net/levin_base.h b/contrib/epee/include/net/levin_base.h
index 7d060f5ef..a88a1eb49 100644
--- a/contrib/epee/include/net/levin_base.h
+++ b/contrib/epee/include/net/levin_base.h
@@ -80,8 +80,8 @@ namespace levin
   template<class t_connection_context = net_utils::connection_context_base>
   struct levin_commands_handler
   {
-    virtual int invoke(int command, const std::string& in_buff, std::string& buff_out, t_connection_context& context)=0;
-    virtual int notify(int command, const std::string& in_buff, t_connection_context& context)=0;
+    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& 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){};
 
     virtual void on_connection_new(t_connection_context& context){};
diff --git a/contrib/epee/include/net/levin_client.h b/contrib/epee/include/net/levin_client.h
index 335f6ba02..76d528234 100644
--- a/contrib/epee/include/net/levin_client.h
+++ b/contrib/epee/include/net/levin_client.h
@@ -57,7 +57,7 @@ namespace levin
 		bool is_connected();
 		bool disconnect();
 
-		virtual int invoke(int command, const std::string& in_buff, std::string& buff_out);
+		virtual int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out);
 		virtual int notify(int command, const std::string& in_buff);
 
 	protected: 
@@ -72,7 +72,7 @@ namespace levin
   {
   public:
 
-    int invoke(int command, const std::string& in_buff, std::string& buff_out);
+    int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out);
     int notify(int command, const std::string& in_buff);
   };
 
diff --git a/contrib/epee/include/net/levin_client.inl b/contrib/epee/include/net/levin_client.inl
index a580e81fd..2f048b027 100644
--- a/contrib/epee/include/net/levin_client.inl
+++ b/contrib/epee/include/net/levin_client.inl
@@ -74,7 +74,7 @@ levin_client_impl::~levin_client_impl()
 }
 //------------------------------------------------------------------------------
 inline
-int levin_client_impl::invoke(int command, const std::string& in_buff, std::string& buff_out)
+int levin_client_impl::invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out)
 {
 	if(!is_connected())
 		return -1;
@@ -133,7 +133,7 @@ int levin_client_impl::notify(int command, const std::string& in_buff)
 //------------------------------------------------------------------------------
 //------------------------------------------------------------------------------
 inline
-  int levin_client_impl2::invoke(int command, const std::string& in_buff, std::string& buff_out)
+  int levin_client_impl2::invoke(int command, epee::span<const uint8_t>string& in_buff, std::string& buff_out)
 {
   if(!is_connected())
     return -1;
diff --git a/contrib/epee/include/net/levin_protocol_handler_async.h b/contrib/epee/include/net/levin_protocol_handler_async.h
index 6b1528caf..264b7aec4 100644
--- a/contrib/epee/include/net/levin_protocol_handler_async.h
+++ b/contrib/epee/include/net/levin_protocol_handler_async.h
@@ -34,6 +34,7 @@
 #include <atomic>
 
 #include "levin_base.h"
+#include "buffer.h"
 #include "misc_language.h"
 #include "syncobj.h"
 #include "misc_os_dependent.h"
@@ -85,11 +86,11 @@ public:
   uint64_t m_max_packet_size; 
   uint64_t m_invoke_timeout;
 
-  int invoke(int command, const std::string& in_buff, 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, const std::string& in_buff, 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 std::string& in_buff, boost::uuids::uuid connection_id);
+  int notify(int command, const epee::span<const uint8_t> in_buff, boost::uuids::uuid connection_id);
   bool close(boost::uuids::uuid connection_id);
   bool update_connection_context(const t_connection_context& contxt);
   bool request_callback(boost::uuids::uuid connection_id);
@@ -143,7 +144,7 @@ public:
   config_type& m_config;
   t_connection_context& m_connection_context;
 
-  std::string m_cache_in_buffer;
+  net_utils::buffer m_cache_in_buffer;
   stream_state m_state;
 
   int32_t m_oponent_protocol_ver;
@@ -151,7 +152,7 @@ public:
 
   struct invoke_response_handler_base
   {
-    virtual bool handle(int res, const std::string& buff, connection_context& context)=0;
+    virtual bool handle(int res, const epee::span<const uint8_t> buff, connection_context& context)=0;
     virtual bool is_timer_started() const=0;
     virtual void cancel()=0;
     virtual bool cancel_timer()=0;
@@ -173,7 +174,7 @@ public:
           if(ec == boost::asio::error::operation_aborted)
             return;
           MINFO(con.get_context_ref() << "Timeout on invoke operation happened, command: " << command << " timeout: " << timeout);
-          std::string fake;
+          epee::span<const uint8_t> fake;
           cb(LEVIN_ERROR_CONNECTION_TIMEDOUT, fake, con.get_context_ref());
           con.close();
           con.finish_outer_call();
@@ -191,7 +192,7 @@ public:
     bool m_timer_cancelled;
     uint64_t m_timeout;
     int m_command;
-    virtual bool handle(int res, const std::string& buff, typename async_protocol_handler::connection_context& context)
+    virtual bool handle(int res, const epee::span<const uint8_t> buff, typename async_protocol_handler::connection_context& context)
     {
       if(!cancel_timer())
         return false;
@@ -207,7 +208,7 @@ public:
     {
       if(cancel_timer())
       {
-        std::string fake;
+        epee::span<const uint8_t> fake;
         m_cb(LEVIN_ERROR_CONNECTION_DESTROYED, fake, m_con.get_context_ref());
         m_con.finish_outer_call();
       }
@@ -237,7 +238,7 @@ public:
           if(ec == boost::asio::error::operation_aborted)
             return;
           MINFO(con.get_context_ref() << "Timeout on invoke operation happened, command: " << command << " timeout: " << timeout);
-          std::string fake;
+          epee::span<const uint8_t> fake;
           cb(LEVIN_ERROR_CONNECTION_TIMEDOUT, fake, con.get_context_ref());
           con.close();
           con.finish_outer_call();
@@ -265,6 +266,7 @@ public:
             m_pservice_endpoint(psnd_hndlr), 
             m_config(config), 
             m_connection_context(conn_context), 
+            m_cache_in_buffer(256 * 1024),
             m_state(stream_state_head)
   {
     m_close_called = 0;
@@ -405,14 +407,7 @@ public:
           break;
         }
         {
-          std::string buff_to_invoke;
-          if(m_cache_in_buffer.size()  == m_current_head.m_cb)
-            buff_to_invoke.swap(m_cache_in_buffer);
-          else
-          {
-            buff_to_invoke.assign(m_cache_in_buffer, 0, (std::string::size_type)m_current_head.m_cb);
-            m_cache_in_buffer.erase(0, (std::string::size_type)m_current_head.m_cb);
-          }
+          epee::span<const uint8_t> buff_to_invoke = m_cache_in_buffer.carve((std::string::size_type)m_current_head.m_cb);
 
           bool is_response = (m_oponent_protocol_ver == LEVIN_PROTOCOL_VER_1 && m_current_head.m_flags&LEVIN_PACKET_RESPONSE);
 
@@ -449,8 +444,8 @@ public:
               }else
               {
                 CRITICAL_REGION_BEGIN(m_local_inv_buff_lock);
-                buff_to_invoke.swap(m_local_inv_buff);
-                buff_to_invoke.clear();
+                m_local_inv_buff = std::string((const char*)buff_to_invoke.data(), buff_to_invoke.size());
+                buff_to_invoke = epee::span<const uint8_t>((const uint8_t*)NULL, 0);
                 m_invoke_result_code = m_current_head.m_return_code;
                 CRITICAL_REGION_END();
                 boost::interprocess::ipcdetail::atomic_write32(&m_invoke_buf_ready, 1);
@@ -503,7 +498,7 @@ public:
         {
           if(m_cache_in_buffer.size() < sizeof(bucket_head2))
           {
-            if(m_cache_in_buffer.size() >= sizeof(uint64_t) && *((uint64_t*)m_cache_in_buffer.data()) != SWAP64LE(LEVIN_SIGNATURE))
+            if(m_cache_in_buffer.size() >= sizeof(uint64_t) && *((uint64_t*)m_cache_in_buffer.span(8).data()) != SWAP64LE(LEVIN_SIGNATURE))
             {
               MWARNING(m_connection_context << "Signature mismatch, connection will be closed");
               return false;
@@ -513,9 +508,9 @@ public:
           }
 
 #if BYTE_ORDER == LITTLE_ENDIAN
-          bucket_head2& phead = *(bucket_head2*)m_cache_in_buffer.data();
+          bucket_head2& phead = *(bucket_head2*)m_cache_in_buffer.span(sizeof(bucket_head2)).data();
 #else
-          bucket_head2 phead = *(bucket_head2*)m_cache_in_buffer.data();
+          bucket_head2 phead = *(bucket_head2*)m_cache_in_buffer.span(sizeof(bucket_head2)).data();
           phead.m_signature = SWAP64LE(phead.m_signature);
           phead.m_cb = SWAP64LE(phead.m_cb);
           phead.m_command = SWAP32LE(phead.m_command);
@@ -530,7 +525,7 @@ public:
           }
           m_current_head = phead;
 
-          m_cache_in_buffer.erase(0, sizeof(bucket_head2));
+          m_cache_in_buffer.erase(sizeof(bucket_head2));
           m_state = stream_state_body;
           m_oponent_protocol_ver = m_current_head.m_protocol_version;
           if(m_current_head.m_cb > m_config.m_max_packet_size)
@@ -562,7 +557,7 @@ public:
   }
 
   template<class callback_t>
-  bool async_invoke(int command, const std::string& in_buff, 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));
@@ -606,7 +601,7 @@ public:
         break;
       }
 
-      if(!m_pservice_endpoint->do_send(in_buff.data(), (int)in_buff.size()))
+      if(!m_pservice_endpoint->do_send(in_buff.data(), in_buff.size()))
       {
         LOG_ERROR_CC(m_connection_context, "Failed to do_send");
         err_code = LEVIN_ERROR_CONNECTION;
@@ -623,7 +618,7 @@ public:
 
     if (LEVIN_OK != err_code)
     {
-      std::string stub_buff;
+      epee::span<const uint8_t> stub_buff{(const uint8_t*)"", 0};
       // Never call callback inside critical section, that can cause deadlock
       cb(err_code, stub_buff, m_connection_context);
       return false;
@@ -632,7 +627,7 @@ public:
     return true;
   }
 
-  int invoke(int command, const std::string& in_buff, 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));
@@ -662,7 +657,7 @@ public:
       return LEVIN_ERROR_CONNECTION;
     }
 
-    if(!m_pservice_endpoint->do_send(in_buff.data(), (int)in_buff.size()))
+    if(!m_pservice_endpoint->do_send(in_buff.data(), in_buff.size()))
     {
       LOG_ERROR_CC(m_connection_context, "Failed to do_send");
       return LEVIN_ERROR_CONNECTION;
@@ -706,7 +701,7 @@ public:
     return m_invoke_result_code;
   }
 
-  int notify(int command, const std::string& in_buff)
+  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));
@@ -734,7 +729,7 @@ public:
       return -1;
     }
 
-    if(!m_pservice_endpoint->do_send(in_buff.data(), (int)in_buff.size()))
+    if(!m_pservice_endpoint->do_send(in_buff.data(), in_buff.size()))
     {
       LOG_ERROR_CC(m_connection_context, "Failed to do_send()");
       return -1;
@@ -839,7 +834,7 @@ 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, const std::string& in_buff, 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);
@@ -847,7 +842,7 @@ int async_protocol_handler_config<t_connection_context>::invoke(int command, con
 }
 //------------------------------------------------------------------------------------------
 template<class t_connection_context> template<class callback_t>
-int async_protocol_handler_config<t_connection_context>::invoke_async(int command, const std::string& in_buff, 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);
@@ -896,7 +891,7 @@ 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 std::string& in_buff, boost::uuids::uuid connection_id)
+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);
diff --git a/contrib/epee/include/span.h b/contrib/epee/include/span.h
index b1296a0b7..cfb5b1a17 100644
--- a/contrib/epee/include/span.h
+++ b/contrib/epee/include/span.h
@@ -163,4 +163,12 @@ namespace epee
     static_assert(!has_padding<T>(), "source type may have padding");
     return {reinterpret_cast<std::uint8_t*>(std::addressof(src)), sizeof(T)};
   }
+
+  //! make a span from a std::string
+  template<typename T>
+  span<const T> strspan(const std::string &s) noexcept
+  {
+    static_assert(std::is_same<T, char>() || std::is_same<T, unsigned char>() || std::is_same<T, int8_t>() || std::is_same<T, uint8_t>(), "Unexpected type");
+    return {reinterpret_cast<const T*>(s.data()), s.size()};
+  }
 }
diff --git a/contrib/epee/include/storages/http_abstract_invoke.h b/contrib/epee/include/storages/http_abstract_invoke.h
index d93084ab0..18b7f10c1 100644
--- a/contrib/epee/include/storages/http_abstract_invoke.h
+++ b/contrib/epee/include/storages/http_abstract_invoke.h
@@ -97,7 +97,7 @@ namespace epee
         return false;
       }
 
-      return serialization::load_t_from_binary(result_struct, pri->m_body);
+      return serialization::load_t_from_binary(result_struct, epee::strspan<uint8_t>(pri->m_body));
     }
 
     template<class t_request, class t_response, class t_transport>
diff --git a/contrib/epee/include/storages/levin_abstract_invoke2.h b/contrib/epee/include/storages/levin_abstract_invoke2.h
index d77e7a1f8..06eb9bdaf 100644
--- a/contrib/epee/include/storages/levin_abstract_invoke2.h
+++ b/contrib/epee/include/storages/levin_abstract_invoke2.h
@@ -28,6 +28,7 @@
 
 #include "portable_storage_template_helper.h"
 #include <boost/utility/value_init.hpp>
+#include "span.h"
 #include "net/levin_base.h"
 
 #undef MONERO_DEFAULT_LOG_CATEGORY
@@ -114,7 +115,7 @@ namespace epee
       const_cast<t_arg&>(out_struct).store(stg);//TODO: add true const support to searilzation
       std::string buff_to_send;
       stg.store_to_binary(buff_to_send);
-      int res = transport.invoke_async(command, buff_to_send, conn_id, [cb, command](int code, const std::string& buff, typename t_transport::connection_context& context)->bool 
+      int res = transport.invoke_async(command, epee::strspan<uint8_t>(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 )
@@ -156,7 +157,7 @@ namespace epee
       std::string buff_to_send;
       stg.store_to_binary(buff_to_send);
 
-      int res = transport.notify(command, buff_to_send, conn_id);
+      int res = transport.notify(command, epee::strspan<uint8_t>(buff_to_send), conn_id);
       if(res <=0 )
       {
         MERROR("Failed to notify command " << command << " return code " << res);
@@ -167,7 +168,7 @@ 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 std::string& in_buff, std::string& buff_out, callback_t cb, t_context& context )
+    int buff_to_t_adapter(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out, callback_t cb, t_context& context )
     {
       serialization::portable_storage strg;
       if(!strg.load_from_binary(in_buff))
@@ -197,7 +198,7 @@ namespace epee
     }
 
     template<class t_owner, class t_in_type, class t_context, class callback_t>
-    int buff_to_t_adapter(t_owner* powner, int command, const std::string& in_buff, callback_t cb, t_context& context)
+    int buff_to_t_adapter(t_owner* powner, int command, const epee::span<const uint8_t> in_buff, callback_t cb, t_context& context)
     {
       serialization::portable_storage strg;
       if(!strg.load_from_binary(in_buff))
@@ -215,14 +216,14 @@ namespace epee
     }
 
 #define CHAIN_LEVIN_INVOKE_MAP2(context_type) \
-  int invoke(int command, const std::string& in_buff, std::string& buff_out, context_type& context) \
+  int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out, context_type& context) \
   { \
   bool handled = false; \
   return handle_invoke_map(false, command, in_buff, buff_out, context, handled); \
   } 
 
 #define CHAIN_LEVIN_NOTIFY_MAP2(context_type) \
-  int notify(int command, const std::string& in_buff, context_type& context) \
+  int notify(int command, const epee::span<const uint8_t> in_buff, context_type& context) \
   { \
   bool handled = false; std::string fake_str;\
   return handle_invoke_map(true, command, in_buff, fake_str, context, handled); \
@@ -230,27 +231,27 @@ namespace epee
 
 
 #define CHAIN_LEVIN_INVOKE_MAP() \
-  int invoke(int command, const std::string& in_buff, std::string& buff_out, epee::net_utils::connection_context_base& context) \
+  int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out, epee::net_utils::connection_context_base& context) \
   { \
   bool handled = false; \
   return handle_invoke_map(false, command, in_buff, buff_out, context, handled); \
   } 
 
 #define CHAIN_LEVIN_NOTIFY_MAP() \
-  int notify(int command, const std::string& in_buff, epee::net_utils::connection_context_base& context) \
+  int notify(int command, const epee::span<const uint8_t> in_buff, epee::net_utils::connection_context_base& context) \
   { \
   bool handled = false; std::string fake_str;\
   return handle_invoke_map(true, command, in_buff, fake_str, context, handled); \
   } 
 
 #define CHAIN_LEVIN_NOTIFY_STUB() \
-  int notify(int command, const std::string& in_buff, epee::net_utils::connection_context_base& context) \
+  int notify(int command, const epee::span<const uint8_t> in_buff, epee::net_utils::connection_context_base& context) \
   { \
   return -1; \
   } 
 
 #define BEGIN_INVOKE_MAP2(owner_type) \
-  template <class t_context> int handle_invoke_map(bool is_notify, int command, const std::string& in_buff, std::string& 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, std::string& buff_out, t_context& context, bool& handled) \
   { \
   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 0f0c6210f..d0e40d606 100644
--- a/contrib/epee/include/storages/portable_storage.h
+++ b/contrib/epee/include/storages/portable_storage.h
@@ -35,6 +35,7 @@
 #include "portable_storage_to_json.h"
 #include "portable_storage_from_json.h"
 #include "portable_storage_val_converters.h"
+#include "span.h"
 #include "int-util.h"
 
 namespace epee
@@ -81,7 +82,8 @@ namespace epee
 
       //-------------------------------------------------------------------------------
       bool		store_to_binary(binarybuffer& target);
-      bool		load_from_binary(const binarybuffer& target);
+      bool		load_from_binary(const epee::span<const uint8_t> target);
+      bool		load_from_binary(const std::string& target) { return load_from_binary(epee::strspan<uint8_t>(target)); }
       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);
@@ -146,7 +148,7 @@ namespace epee
       CATCH_ENTRY("portable_storage::store_to_binary", false)
     }
     inline
-    bool portable_storage::load_from_binary(const binarybuffer& source)
+    bool portable_storage::load_from_binary(const epee::span<const uint8_t> source)
     {
       m_root.m_entries.clear();
       if(source.size() < sizeof(storage_block_header))
diff --git a/contrib/epee/include/storages/portable_storage_template_helper.h b/contrib/epee/include/storages/portable_storage_template_helper.h
index bbd8413fc..13c870d44 100644
--- a/contrib/epee/include/storages/portable_storage_template_helper.h
+++ b/contrib/epee/include/storages/portable_storage_template_helper.h
@@ -84,7 +84,7 @@ namespace epee
     }
     //-----------------------------------------------------------------------------------------------------------
     template<class t_struct>
-    bool load_t_from_binary(t_struct& out, const std::string& binary_buff)
+    bool load_t_from_binary(t_struct& out, const epee::span<const uint8_t> binary_buff)
     {
       portable_storage ps;
       bool rs = ps.load_from_binary(binary_buff);
@@ -95,6 +95,12 @@ namespace epee
     }
     //-----------------------------------------------------------------------------------------------------------
     template<class t_struct>
+    bool load_t_from_binary(t_struct& out, const std::string& binary_buff)
+    {
+      return load_t_from_binary(out, epee::strspan<uint8_t>(binary_buff));
+    }
+    //-----------------------------------------------------------------------------------------------------------
+    template<class t_struct>
     bool load_t_from_binary_file(t_struct& out, const std::string& binary_file)
     {
       std::string f_buff;
diff --git a/contrib/epee/src/CMakeLists.txt b/contrib/epee/src/CMakeLists.txt
index bc437deb9..cea50c9dd 100644
--- a/contrib/epee/src/CMakeLists.txt
+++ b/contrib/epee/src/CMakeLists.txt
@@ -27,7 +27,7 @@
 # THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 add_library(epee STATIC hex.cpp http_auth.cpp mlog.cpp net_utils_base.cpp string_tools.cpp wipeable_string.cpp memwipe.c
-    connection_basic.cpp network_throttle.cpp network_throttle-detail.cpp mlocker.cpp)
+    connection_basic.cpp network_throttle.cpp network_throttle-detail.cpp mlocker.cpp buffer.cpp)
 if (USE_READLINE AND GNU_READLINE_FOUND)
   add_library(epee_readline STATIC readline_buffer.cpp)
 endif()
diff --git a/contrib/epee/src/buffer.cpp b/contrib/epee/src/buffer.cpp
new file mode 100644
index 000000000..d637b905e
--- /dev/null
+++ b/contrib/epee/src/buffer.cpp
@@ -0,0 +1,97 @@
+// Copyright (c) 2018, 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.
+
+#include <string.h>
+#include "net/buffer.h"
+
+#undef MONERO_DEFAULT_LOG_CATEGORY
+#define MONERO_DEFAULT_LOG_CATEGORY "net.buffer"
+
+namespace epee
+{
+namespace net_utils
+{
+
+void buffer::append(const void *data, size_t sz)
+{
+  const size_t capacity = storage.capacity();
+  const size_t avail = capacity - storage.size();
+
+  CHECK_AND_ASSERT_THROW_MES(storage.size() < std::numeric_limits<size_t>::max() - sz, "Too much data to append");
+
+  // decide when to move
+  if (sz > avail)
+  {
+    // we have to reallocate or move
+    const bool move = size() + sz <= capacity;
+    if (move)
+    {
+      const size_t bytes = storage.size() - offset;
+      NET_BUFFER_LOG("appending " << sz << " from " << size() << " by moving " << bytes << " from offset " << offset << " first (forced)");
+      memmove(storage.data(), storage.data() + offset, bytes);
+      storage.resize(bytes);
+      offset = 0;
+    }
+    else
+    {
+      NET_BUFFER_LOG("appending " << sz << " from " << size() << " by reallocating");
+      std::vector<uint8_t> new_storage;
+      size_t reserve = (((size() + sz) * 3 / 2) + 4095) & ~4095;
+      new_storage.reserve(reserve);
+      new_storage.resize(size());
+      memcpy(new_storage.data(), storage.data() + offset, storage.size() - offset);
+      offset = 0;
+      std::swap(storage, new_storage);
+    }
+  }
+  else
+  {
+    // we have space already
+    if (size() <= 4096 && offset > 4096 * 16 && offset >= capacity / 2)
+    {
+      // we have little to move, and we're far enough into the buffer that it's probably a win to move anyway
+      const size_t pos = storage.size() - offset;
+      NET_BUFFER_LOG("appending " << sz << " from " << size() << " by moving " << pos << " from offset " << offset << " first (unforced)");
+      memmove(storage.data(), storage.data() + offset, storage.size() - offset);
+      storage.resize(pos);
+      offset = 0;
+    }
+    else
+    {
+      NET_BUFFER_LOG("appending " << sz << " from " << size() << " by writing to existing capacity");
+    }
+  }
+
+  // add the new data
+  storage.insert(storage.end(), (const uint8_t*)data, (const uint8_t*)data + sz);
+
+  NET_BUFFER_LOG("storage now " << offset << "/" << storage.size() << "/" << storage.capacity());
+}
+
+}
+}
diff --git a/src/cryptonote_protocol/cryptonote_protocol_handler.h b/src/cryptonote_protocol/cryptonote_protocol_handler.h
index d7b74c06d..6ed46c625 100644
--- a/src/cryptonote_protocol/cryptonote_protocol_handler.h
+++ b/src/cryptonote_protocol/cryptonote_protocol_handler.h
@@ -155,7 +155,7 @@ namespace cryptonote
         std::string blob;
         epee::serialization::store_t_to_binary(arg, blob);
         //handler_response_blocks_now(blob.size()); // XXX
-        return m_p2p->invoke_notify_to_peer(t_parameter::ID, blob, context);
+        return m_p2p->invoke_notify_to_peer(t_parameter::ID, epee::strspan<uint8_t>(blob), context);
       }
 
       template<class t_parameter>
@@ -164,7 +164,7 @@ namespace cryptonote
         LOG_PRINT_L2("[" << epee::net_utils::print_connection_context_short(exclude_context) << "] post relay " << typeid(t_parameter).name() << " -->");
         std::string arg_buff;
         epee::serialization::store_t_to_binary(arg, arg_buff);
-        return m_p2p->relay_notify_to_all(t_parameter::ID, arg_buff, exclude_context);
+        return m_p2p->relay_notify_to_all(t_parameter::ID, epee::strspan<uint8_t>(arg_buff), exclude_context);
       }
   };
 
diff --git a/src/cryptonote_protocol/cryptonote_protocol_handler.inl b/src/cryptonote_protocol/cryptonote_protocol_handler.inl
index 1de0cde07..290125dde 100644
--- a/src/cryptonote_protocol/cryptonote_protocol_handler.inl
+++ b/src/cryptonote_protocol/cryptonote_protocol_handler.inl
@@ -1710,13 +1710,13 @@ skip:
     {
       std::string fluffyBlob;
       epee::serialization::store_t_to_binary(fluffy_arg, fluffyBlob);
-      m_p2p->relay_notify_to_list(NOTIFY_NEW_FLUFFY_BLOCK::ID, fluffyBlob, fluffyConnections);
+      m_p2p->relay_notify_to_list(NOTIFY_NEW_FLUFFY_BLOCK::ID, epee::strspan<uint8_t>(fluffyBlob), fluffyConnections);
     }
     if (!fullConnections.empty())
     {
       std::string fullBlob;
       epee::serialization::store_t_to_binary(arg, fullBlob);
-      m_p2p->relay_notify_to_list(NOTIFY_NEW_BLOCK::ID, fullBlob, fullConnections);
+      m_p2p->relay_notify_to_list(NOTIFY_NEW_BLOCK::ID, epee::strspan<uint8_t>(fullBlob), fullConnections);
     }
 
     return true;
diff --git a/src/p2p/net_node.h b/src/p2p/net_node.h
index 8930418bd..46f560615 100644
--- a/src/p2p/net_node.h
+++ b/src/p2p/net_node.h
@@ -180,10 +180,10 @@ 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, const std::string& data_buff, const std::list<boost::uuids::uuid> &connections);
-    virtual bool relay_notify_to_all(int command, const std::string& data_buff, const epee::net_utils::connection_context_base& context);
-    virtual bool invoke_command_to_peer(int command, const std::string& req_buff, std::string& resp_buff, const epee::net_utils::connection_context_base& context);
-    virtual bool invoke_notify_to_peer(int command, const std::string& req_buff, const epee::net_utils::connection_context_base& context);
+    virtual bool relay_notify_to_list(int command, const epee::span<const uint8_t> data_buff, const std::list<boost::uuids::uuid> &connections);
+    virtual bool relay_notify_to_all(int command, const epee::span<const uint8_t> data_buff, 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);
+    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 fbf265fc9..8c2224ec7 100644
--- a/src/p2p/net_node.inl
+++ b/src/p2p/net_node.inl
@@ -1516,7 +1516,7 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
-  bool node_server<t_payload_net_handler>::relay_notify_to_list(int command, const std::string& data_buff, const std::list<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, const std::list<boost::uuids::uuid> &connections)
   {
     for(const auto& c_id: connections)
     {
@@ -1526,7 +1526,7 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
-  bool node_server<t_payload_net_handler>::relay_notify_to_all(int command, const std::string& data_buff, const epee::net_utils::connection_context_base& context)
+  bool node_server<t_payload_net_handler>::relay_notify_to_all(int command, const epee::span<const uint8_t> data_buff, const epee::net_utils::connection_context_base& context)
   {
     std::list<boost::uuids::uuid> connections;
     m_net_server.get_config_object().foreach_connection([&](const p2p_connection_context& cntxt)
@@ -1545,14 +1545,14 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
-  bool node_server<t_payload_net_handler>::invoke_notify_to_peer(int command, const std::string& req_buff, 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)
   {
     int res = 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 std::string& req_buff, std::string& resp_buff, const epee::net_utils::connection_context_base& context)
+  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)
   {
     int res = 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 218250efa..656c6155b 100644
--- a/src/p2p/net_node_common.h
+++ b/src/p2p/net_node_common.h
@@ -43,10 +43,10 @@ namespace nodetool
   template<class t_connection_context>
   struct i_p2p_endpoint
   {
-    virtual bool relay_notify_to_list(int command, const std::string& data_buff, const std::list<boost::uuids::uuid>& connections)=0;
-    virtual bool relay_notify_to_all(int command, const std::string& data_buff, const epee::net_utils::connection_context_base& context)=0;
-    virtual bool invoke_command_to_peer(int command, const std::string& req_buff, std::string& resp_buff, const epee::net_utils::connection_context_base& context)=0;
-    virtual bool invoke_notify_to_peer(int command, const std::string& req_buff, const epee::net_utils::connection_context_base& context)=0;
+    virtual bool relay_notify_to_list(int command, const epee::span<const uint8_t> data_buff, const std::list<boost::uuids::uuid>& connections)=0;
+    virtual bool relay_notify_to_all(int command, const epee::span<const uint8_t> data_buff, 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_connections_count()=0;
@@ -61,19 +61,19 @@ 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, const std::string& data_buff, const std::list<boost::uuids::uuid>& connections)
+    virtual bool relay_notify_to_list(int command, const epee::span<const uint8_t> data_buff, const std::list<boost::uuids::uuid>& connections)
     {
       return false;
     }
-    virtual bool relay_notify_to_all(int command, const std::string& data_buff, const epee::net_utils::connection_context_base& context)
+    virtual bool relay_notify_to_all(int command, const epee::span<const uint8_t> data_buff, const epee::net_utils::connection_context_base& context)
     {
       return false;
     }
-    virtual bool invoke_command_to_peer(int command, const std::string& req_buff, std::string& resp_buff, 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 std::string& req_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)
     {
       return true;
     }
diff --git a/tests/fuzz/levin.cpp b/tests/fuzz/levin.cpp
index d0c5803f5..573abd1d3 100644
--- a/tests/fuzz/levin.cpp
+++ b/tests/fuzz/levin.cpp
@@ -65,22 +65,22 @@ namespace
     {
     }
 
-    virtual int invoke(int command, const std::string& in_buff, std::string& buff_out, test_levin_connection_context& context)
+    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& 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 = in_buff;
+      m_last_in_buf = std::string((const char*)in_buff.data(), in_buff.size());
       buff_out = m_invoke_out_buf;
       return m_return_code;
     }
 
-    virtual int notify(int command, const std::string& in_buff, test_levin_connection_context& context)
+    virtual int notify(int command, const epee::span<const uint8_t> in_buff, test_levin_connection_context& context)
     {
       m_notify_counter.inc();
       boost::unique_lock<boost::mutex> lock(m_mutex);
       m_last_command = command;
-      m_last_in_buf = in_buff;
+      m_last_in_buf = std::string((const char*)in_buff.data(), in_buff.size());
       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 7e92c21b9..f2ecfc8b0 100644
--- a/tests/net_load_tests/net_load_tests.h
+++ b/tests/net_load_tests/net_load_tests.h
@@ -62,7 +62,7 @@ namespace net_load_tests
     {
     }
 
-    virtual int invoke(int command, const std::string& in_buff, std::string& buff_out, test_connection_context& context)
+    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& buff_out, test_connection_context& context)
     {
       //m_invoke_counter.inc();
       //std::unique_lock<std::mutex> lock(m_mutex);
@@ -73,7 +73,7 @@ namespace net_load_tests
       return LEVIN_OK;
     }
 
-    virtual int notify(int command, const std::string& in_buff, test_connection_context& context)
+    virtual int notify(int command, const epee::span<const uint8_t> in_buff, test_connection_context& context)
     {
       //m_notify_counter.inc();
       //std::unique_lock<std::mutex> lock(m_mutex);
diff --git a/tests/unit_tests/epee_levin_protocol_handler_async.cpp b/tests/unit_tests/epee_levin_protocol_handler_async.cpp
index 10e62c167..9ea71875b 100644
--- a/tests/unit_tests/epee_levin_protocol_handler_async.cpp
+++ b/tests/unit_tests/epee_levin_protocol_handler_async.cpp
@@ -56,22 +56,22 @@ namespace
     {
     }
 
-    virtual int invoke(int command, const std::string& in_buff, std::string& buff_out, test_levin_connection_context& context)
+    virtual int invoke(int command, const epee::span<const uint8_t> in_buff, std::string& 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 = in_buff;
+      m_last_in_buf = std::string((const char*)in_buff.data(), in_buff.size());
       buff_out = m_invoke_out_buf;
       return m_return_code;
     }
 
-    virtual int notify(int command, const std::string& in_buff, test_levin_connection_context& context)
+    virtual int notify(int command, const epee::span<const uint8_t> in_buff, test_levin_connection_context& context)
     {
       m_notify_counter.inc();
       boost::unique_lock<boost::mutex> lock(m_mutex);
       m_last_command = command;
-      m_last_in_buf = in_buff;
+      m_last_in_buf = std::string((const char*)in_buff.data(), in_buff.size());
       return m_return_code;
     }
 
diff --git a/tests/unit_tests/epee_utils.cpp b/tests/unit_tests/epee_utils.cpp
index c384ce9a5..75cf2fdd4 100644
--- a/tests/unit_tests/epee_utils.cpp
+++ b/tests/unit_tests/epee_utils.cpp
@@ -46,6 +46,7 @@
 #include "hex.h"
 #include "net/net_utils_base.h"
 #include "net/local_ip.h"
+#include "net/buffer.h"
 #include "p2p/net_peerlist_boost_serialization.h"
 #include "span.h"
 #include "string_tools.h"
@@ -764,3 +765,71 @@ TEST(NetUtils, PrivateRanges)
   ASSERT_EQ(is_local("0.0.30.172"), false);
   ASSERT_EQ(is_local("0.0.30.127"), false);
 }
+
+TEST(net_buffer, basic)
+{
+  epee::net_utils::buffer buf;
+
+  ASSERT_EQ(buf.size(), 0);
+  EXPECT_THROW(buf.span(1), std::runtime_error);
+  buf.append("a", 1);
+  epee::span<const uint8_t> span = buf.span(1);
+  ASSERT_EQ(span.size(), 1);
+  ASSERT_EQ(span.data()[0], 'a');
+  EXPECT_THROW(buf.span(2), std::runtime_error);
+  buf.append("bc", 2);
+  buf.erase(1);
+  EXPECT_THROW(buf.span(3), std::runtime_error);
+  span = buf.span(2);
+  ASSERT_EQ(span.size(), 2);
+  ASSERT_EQ(span.data()[0], 'b');
+  ASSERT_EQ(span.data()[1], 'c');
+  buf.erase(1);
+  EXPECT_THROW(buf.span(2), std::runtime_error);
+  span = buf.span(1);
+  ASSERT_EQ(span.size(), 1);
+  ASSERT_EQ(span.data()[0], 'c');
+  EXPECT_THROW(buf.erase(2), std::runtime_error);
+  buf.erase(1);
+  EXPECT_EQ(buf.size(), 0);
+  EXPECT_THROW(buf.span(1), std::runtime_error);
+}
+
+TEST(net_buffer, existing_capacity)
+{
+  epee::net_utils::buffer buf;
+
+  buf.append("123456789", 9);
+  buf.erase(9);
+  buf.append("abc", 3);
+  buf.append("def", 3);
+  ASSERT_EQ(buf.size(), 6);
+  epee::span<const uint8_t> span = buf.span(6);
+  ASSERT_TRUE(!memcmp(span.data(), "abcdef", 6));
+}
+
+TEST(net_buffer, reallocate)
+{
+  epee::net_utils::buffer buf;
+
+  buf.append(std::string(4000, ' ').c_str(), 4000);
+  buf.append(std::string(8000, '0').c_str(), 8000);
+  ASSERT_EQ(buf.size(), 12000);
+  epee::span<const uint8_t> span = buf.span(12000);
+  ASSERT_TRUE(!memcmp(span.data(), std::string(4000, ' ').c_str(), 4000));
+  ASSERT_TRUE(!memcmp(span.data() + 4000, std::string(8000, '0').c_str(), 8000));
+}
+
+TEST(net_buffer, move)
+{
+  epee::net_utils::buffer buf;
+
+  buf.append(std::string(400, ' ').c_str(), 400);
+  buf.erase(399);
+  buf.append(std::string(4000, '0').c_str(), 4000);
+  ASSERT_EQ(buf.size(), 4001);
+  epee::span<const uint8_t> span = buf.span(4001);
+  ASSERT_TRUE(!memcmp(span.data(), std::string(1, ' ').c_str(), 1));
+  ASSERT_TRUE(!memcmp(span.data() + 1, std::string(4000, '0').c_str(), 4000));
+}
+