From 2e5c56205c210dc7b6e0446f87d54c5e3fef5fba Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Thu, 24 Mar 2016 14:48:07 -0400
Subject: [PATCH] address resolver

---
 AddressBook.cpp | 81 +++++++++++++++++++++++++++++++++++++++++++++++--
 AddressBook.h   | 26 ++++++++++++++--
 2 files changed, 103 insertions(+), 4 deletions(-)

diff --git a/AddressBook.cpp b/AddressBook.cpp
index 22008294..f972d48f 100644
--- a/AddressBook.cpp
+++ b/AddressBook.cpp
@@ -330,8 +330,7 @@ namespace client
 			LoadHostsFromStream (f);
 			m_IsLoaded = true;
 		}
-		// load local
-		m_Storage->LoadLocal (m_Addresses);
+		LoadLocal ();
 	}
 
 	void AddressBook::LoadHostsFromStream (std::istream& f)
@@ -395,6 +394,40 @@ namespace client
 			LogPrint (eLogError, "Addressbook: subscriptions already loaded");
 	}
 
+	void AddressBook::LoadLocal ()
+	{
+		std::map<std::string, i2p::data::IdentHash> localAddresses;
+		m_Storage->LoadLocal (localAddresses);
+		for (auto it: localAddresses)
+		{
+			auto dot = it.first.find ('.');
+			if (dot != std::string::npos)
+			{
+				auto domain = it.first.substr (dot + 1);
+				auto it1 = m_Addresses.find (domain);  // find domain in our addressbook
+				if (it1 != m_Addresses.end ())
+				{
+					auto dest = context.FindLocalDestination (it1->second);
+					if (dest) 
+					{
+						// address is ours
+						std::shared_ptr<AddressResolver> resolver;
+						auto it2 = m_Resolvers.find (it1->second); 
+						if (it2 != m_Resolvers.end ())
+							resolver = it2->second; // resolver exists
+						else
+						{
+							// create new resolver
+							resolver = std::make_shared<AddressResolver>(dest);
+							m_Resolvers.insert (std::make_pair(it1->second, resolver));
+						}
+						resolver->AddAddress (it.first, it.second);
+					}
+				}
+			}
+		}
+	}
+
 	bool AddressBook::GetEtag (const i2p::data::IdentHash& subscription, std::string& etag, std::string& lastModified)
 	{
 		if (m_Storage)
@@ -653,6 +686,50 @@ namespace client
 			m_Book.LoadHostsFromStream (s);
 		return true;	
 	}
+
+	AddressResolver::AddressResolver (std::shared_ptr<ClientDestination> destination):
+		m_LocalDestination (destination)
+	{
+		if (m_LocalDestination)
+		{
+			auto datagram = m_LocalDestination->GetDatagramDestination ();
+			if (!datagram)
+				datagram = m_LocalDestination->CreateDatagramDestination ();
+			datagram->SetReceiver (std::bind (&AddressResolver::HandleRequest, this, 
+				std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4, std::placeholders::_5), 
+				ADDRESS_RESOLVER_DATAGRAM_PORT);
+		}
+	}
+
+	void AddressResolver::HandleRequest (const i2p::data::IdentityEx& from, uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len)
+	{
+		if (len < 9 || len < buf[8] + 9U)
+		{
+			LogPrint (eLogError, "Address request is too short ", len);
+			return;
+		}
+		// read requested address
+		uint8_t l = buf[8];
+		char address[255];
+		memcpy (address, buf + 9, l);
+		address[l] = 0;		 		
+		// send response
+		uint8_t response[40];
+		memset (response, 0, 4); // reserved
+		memcpy (response + 4, buf + 4, 4); // nonce 	
+		auto it = m_LocalAddresses.find (address); // address lookup
+		if (it != m_LocalAddresses.end ())	
+			memcpy (response + 8, it->second, 32); // ident 
+		else
+			memset (response + 8, 0, 32); // not found 
+		m_LocalDestination->GetDatagramDestination ()->SendDatagramTo (response, 40, from.GetIdentHash (), toPort, fromPort);
+	}
+
+	void AddressResolver::AddAddress (const std::string& name, const i2p::data::IdentHash& ident)
+	{
+		m_LocalAddresses[name] = ident;		
+	}
+
 }
 }
 
diff --git a/AddressBook.h b/AddressBook.h
index 98422fe1..436e7c8b 100644
--- a/AddressBook.h
+++ b/AddressBook.h
@@ -12,6 +12,7 @@
 #include "Base.h"
 #include "Identity.h"
 #include "Log.h"
+#include "Destination.h"
 
 namespace i2p
 {
@@ -23,7 +24,7 @@ namespace client
 	const int CONTINIOUS_SUBSCRIPTION_UPDATE_TIMEOUT = 720; // in minutes (12 hours)			
 	const int CONTINIOUS_SUBSCRIPTION_RETRY_TIMEOUT = 5; // in minutes	
 	const int SUBSCRIPTION_REQUEST_TIMEOUT = 60; //in second
-	
+
 	inline std::string GetB32Address(const i2p::data::IdentHash& ident) { return ident.ToBase32().append(".b32.i2p"); }
 
 	class AddressBookStorage // interface for storage
@@ -45,6 +46,7 @@ namespace client
 	};			
 
 	class AddressBookSubscription;
+	class AddressResolver;
 	class AddressBook
 	{
 		public:
@@ -74,13 +76,15 @@ namespace client
 			
 			void LoadHosts ();
 			void LoadSubscriptions ();
+			void LoadLocal ();
 
 			void HandleSubscriptionsUpdateTimer (const boost::system::error_code& ecode);
 
 		private:	
 
 			std::mutex m_AddressBookMutex;
-			std::map<std::string, i2p::data::IdentHash>  m_Addresses, m_LocalAddresses;
+			std::map<std::string, i2p::data::IdentHash>  m_Addresses;
+			std::map<i2p::data::IdentHash, std::shared_ptr<AddressResolver> > m_Resolvers; // local destination->resolver
 			AddressBookStorage * m_Storage;
 			volatile bool m_IsLoaded, m_IsDownloading;
 			std::vector<AddressBookSubscription *> m_Subscriptions;
@@ -106,6 +110,24 @@ namespace client
 			std::string m_Link, m_Etag, m_LastModified;
 			// m_Etag must be surrounded by ""
 	};
+
+	const uint16_t ADDRESS_RESOLVER_DATAGRAM_PORT = 53;	
+	class AddressResolver
+	{
+		public:
+
+			AddressResolver (std::shared_ptr<ClientDestination> destination);
+			void AddAddress (const std::string& name, const i2p::data::IdentHash& ident);
+
+		private:
+
+			void HandleRequest (const i2p::data::IdentityEx& from, uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len);
+
+		private:
+
+			std::shared_ptr<ClientDestination> m_LocalDestination;
+			std::map<std::string, i2p::data::IdentHash>  m_LocalAddresses;
+	};
 }
 }