send options in Datagram3

libi2pd/Datagram.cpp

@@ -56,7 +56,8 @@ namespace datagram
 		return ObtainSession(ident);
 	}
 
-	void DatagramDestination::SendDatagram (std::shared_ptr<DatagramSession> session, const uint8_t * payload, size_t len, uint16_t fromPort, uint16_t toPort)
+	void DatagramDestination::SendDatagram (std::shared_ptr<DatagramSession> session, const uint8_t * payload, size_t len,
+		uint16_t fromPort, uint16_t toPort, const i2p::util::Mapping * options)
 	{
 		if (session)
 		{
@@ -65,7 +66,16 @@ namespace datagram
 			{
 				case eDatagramV3:
 				{
-					constexpr uint8_t flags[] = { 0x00, 0x03 }; // datagram3, no options
+					uint8_t flags[] = { 0x00, 0x03 }; // datagram3, no options
+					if (options)
+					{
+						uint8_t optionsBuf[256]; // TODO: evaluate actual size
+						size_t optionsLen = options->ToBuffer (optionsBuf, 256);
+						if (optionsLen) flags[1] |= DATAGRAM3_FLAG_OPTIONS;
+						msg = CreateDataMessage ({{m_Owner->GetIdentity ()->GetIdentHash (), 32}, {flags, 2}, 
+							{optionsBuf, optionsLen}, {payload, len}}, fromPort, toPort, i2p::client::PROTOCOL_TYPE_DATAGRAM3, false); // datagram3
+					}	
+					else
 						msg = CreateDataMessage ({{m_Owner->GetIdentity ()->GetIdentHash (), 32}, 
 							{flags, 2}, {payload, len}}, fromPort, toPort, i2p::client::PROTOCOL_TYPE_DATAGRAM3, false); // datagram3
 					break;

libi2pd/Datagram.h

@@ -139,7 +139,8 @@ namespace datagram
 			// TODO: implement calls from other thread from SAM
 
 			std::shared_ptr<DatagramSession> GetSession(const i2p::data::IdentHash & ident);
-			void SendDatagram (std::shared_ptr<DatagramSession> session, const uint8_t * payload, size_t len, uint16_t fromPort, uint16_t toPort);
+			void SendDatagram (std::shared_ptr<DatagramSession> session, const uint8_t * payload, size_t len, 
+				uint16_t fromPort, uint16_t toPort, const i2p::util::Mapping * options = nullptr);
 			void SendRawDatagram (std::shared_ptr<DatagramSession> session, const uint8_t * payload, size_t len, uint16_t fromPort, uint16_t toPort);
 			void FlushSendQueue (std::shared_ptr<DatagramSession> session);
 

libi2pd/util.cpp

@@ -266,7 +266,7 @@ namespace util
 		return { (const char *)(buf + 1), l };
 	}
 
-	size_t Mapping::ToBuffer (uint8_t * buf, size_t len)
+	size_t Mapping::ToBuffer (uint8_t * buf, size_t len) const
 	{
 		size_t offset = 2;
 		for (auto it: m_Options)

libi2pd/util.h

@@ -17,6 +17,7 @@
 #include <mutex>
 #include <thread>
 #include <utility>
+#include <charconv>
 #include <boost/asio.hpp>
 
 #ifdef ANDROID
@@ -234,7 +235,7 @@ namespace util
 			Mapping () = default;
 			size_t FromBuffer (const uint8_t * buf, size_t len);
 			size_t FromBuffer (size_t size, const uint8_t * buf, size_t len); //without 2 bytes size
-			size_t ToBuffer (uint8_t * buf, size_t len);
+			size_t ToBuffer (uint8_t * buf, size_t len) const;
 			
 			std::string_view operator[](std::string_view param) const;
 			bool Insert (std::string_view param, std::string_view value);
@@ -245,6 +246,20 @@ namespace util
 			static size_t WriteString (std::string_view str, uint8_t * buf, size_t len);
 			static size_t WriteOption (std::string_view param, std::string_view value, uint8_t * buf, size_t len);
 
+			template<typename T>
+			bool Get(std::string_view param, T& value)
+			{
+				auto s = (*this)[param];
+				if (s.empty ()) return false;
+				auto res = std::from_chars(s.data(), s.data() + s.size(), value);
+				return res.ec != std::errc();
+			}	
+			template<typename T>
+			bool Put (std::string_view param, T value)
+			{
+				return Insert (param, std::to_string (value));
+			}	
+			
 		private:
 
 			std::map<std::string, std::string, std::less<> > m_Options;