initial commit for Kademlia DHT

libi2pd/KadDHT.cpp

@@ -0,0 +1,238 @@
+/*
+* Copyright (c) 2023, The PurpleI2P Project
+*
+* This file is part of Purple i2pd project and licensed under BSD3
+*
+* See full license text in LICENSE file at top of project tree
+*
+*/
+
+#include "KadDHT.h"
+
+namespace i2p 
+{
+namespace data 
+{
+	DHTNode::DHTNode ():
+		zero (nullptr), one (nullptr), hash (nullptr)
+	{
+	}
+	
+	DHTNode::~DHTNode ()
+	{
+		if (zero) delete zero;
+		if (one) delete one;
+		if (hash) delete hash;
+	}	
+
+	void DHTNode::MoveHashUp (bool fromOne)
+	{
+		DHTNode *& side = fromOne ? one : zero;
+		if (side)
+		{
+			if (hash) delete hash; // shouldn't happen
+			hash = side->hash;
+			side->hash = nullptr;
+			delete side;
+			side = nullptr;
+		}	
+	}	
+		
+	DHTTable::DHTTable (): 
+		m_Size (0)
+	{
+		m_Root = new DHTNode;
+	}
+		
+	DHTTable::~DHTTable ()
+	{
+		delete m_Root;
+	}	
+
+	DHTNode * DHTTable::Insert (const IdentHash& h)
+	{
+		return Insert (new IdentHash (h), m_Root, 0);
+	}	
+
+	DHTNode * DHTTable::Insert (IdentHash * h, DHTNode * root, int level)
+	{
+		if (root->hash)
+		{	
+			if (*(root->hash) == *h) 
+			{
+				delete h;
+				return root;
+			}	
+			auto h2 = root->hash;
+			root->hash = nullptr; m_Size--;
+			int bit1, bit2;
+			do
+			{	
+				bit1 = h->GetBit (level);
+				bit2 = h2->GetBit (level);
+				if (bit1 == bit2)
+				{	
+					if (bit1)
+					{
+						if (root->one) return nullptr; // someting wrong
+						root->one = new DHTNode;
+						root = root->one;
+					}	
+					else
+					{
+						if (root->zero) return nullptr; // someting wrong
+						root->zero = new DHTNode;
+						root = root->zero;
+					}	
+					level++;
+				}	
+			}
+			while (bit1 == bit2);
+			
+			if (!root->zero)
+				root->zero = new DHTNode;
+			if (!root->one)
+				root->one = new DHTNode;
+			if (bit1)
+			{
+				Insert (h2, root->zero, level + 1);
+				return Insert (h, root->one, level + 1);
+			}
+			else
+			{
+				Insert (h2, root->one, level + 1);
+				return Insert (h, root->zero, level + 1);
+			}	
+		}
+		else
+		{
+			if (!root->zero && !root->one)
+			{
+				root->hash = h; m_Size++;
+				return root;
+			}
+			int bit = h->GetBit (level);
+			if (bit)
+			{
+				if (!root->one)
+					root->one = new DHTNode;
+				return Insert (h, root->one, level + 1);
+			}	
+			else
+			{
+				if (!root->zero)
+					root->zero = new DHTNode;
+				return Insert (h, root->zero, level + 1);
+			}	
+		}	
+		return nullptr;
+	}	
+
+	bool DHTTable::Remove (const IdentHash& h)
+	{
+		return Remove (h, m_Root, 0);
+	}	
+		
+	bool DHTTable::Remove (const IdentHash& h, DHTNode * root, int level)
+	{
+		if (root)
+		{
+			if (root->hash && *(root->hash) == h)
+			{
+				delete root->hash; root->hash = nullptr;
+				m_Size--;
+				return true;
+			}	
+			int bit = h.GetBit (level);
+			if (bit)
+			{
+				if (root->one && Remove (h, root->one, level + 1))
+				{    
+					if (root->one->IsEmpty ())
+					{
+						delete root->one;
+						root->one = nullptr;
+						if (root->zero && root->zero->hash)
+							root->MoveHashUp (false);
+					}	
+					else if (root->one->hash && !root->zero)
+						root->MoveHashUp (true);
+					return true;
+				}	
+			}
+			else
+			{
+				if (root->zero && Remove (h, root->zero, level + 1))
+				{    
+					if (root->zero->IsEmpty ())
+					{
+						delete root->zero;
+						root->zero = nullptr;
+						if (root->one && root->one->hash)
+							root->MoveHashUp (true);
+					}	
+					else if (root->zero->hash && !root->one)
+						root->MoveHashUp (false);
+					return true;
+				}
+			}	
+		}	
+		return false;
+	}	
+
+	IdentHash * DHTTable::FindClosest (const IdentHash& h)
+	{
+		return FindClosest (h, m_Root, 0);
+	}	
+
+	IdentHash * DHTTable::FindClosest (const IdentHash& h, DHTNode * root, int level)
+	{
+		if (root->hash) return root->hash;
+		int bit = h.GetBit (level);
+		if (bit)
+		{
+			if (root->one)
+				return FindClosest (h, root->one, level + 1);
+			if (root->zero)
+				return FindClosest (h, root->zero, level + 1);
+		}	
+		else
+		{
+			if (root->zero)
+				return FindClosest (h, root->zero, level + 1);
+			if (root->one)
+				return FindClosest (h, root->one, level + 1);
+		}
+		return nullptr;
+	}	
+		
+	void DHTTable::Print (std::stringstream& s)
+	{
+		Print (s, m_Root, 0);
+	}	
+
+	void DHTTable::Print (std::stringstream& s, DHTNode * root, int level)
+	{
+		if (!root) return;
+		s << std::string (level, '-');
+		if (root->hash)
+		{
+			if (!root->zero && !root->one)
+				s << '>' << GetIdentHashAbbreviation (*(root->hash));
+			else	
+				s << "error";
+		}	
+		s << std::endl;
+		if (root->zero)
+		{
+			s << std::string (level, '-') << "0" << std::endl;
+			Print (s, root->zero, level + 1);
+		}	
+		if (root->one)
+		{
+			s << std::string (level, '-') << "1" << std::endl;
+			Print (s, root->one, level + 1);
+		}	
+	}	
+}
+}

libi2pd/KadDHT.h

@@ -0,0 +1,64 @@
+/*
+* Copyright (c) 2023, The PurpleI2P Project
+*
+* This file is part of Purple i2pd project and licensed under BSD3
+*
+* See full license text in LICENSE file at top of project tree
+*
+*/
+
+#ifndef KADDHT_H__
+#define KADDHT_H__
+
+#include <memory>
+#include <sstream>
+#include "Identity.h"
+
+// Kademlia DHT (XOR distance)
+
+namespace i2p 
+{
+namespace data 
+{
+	struct DHTNode
+	{
+		DHTNode * zero, * one;
+		IdentHash * hash;
+
+		DHTNode ();
+		~DHTNode (); 
+
+		bool IsEmpty () const { return !zero && !one && !hash; };
+		void MoveHashUp (bool fromOne);
+	};
+
+	class DHTTable 
+	{
+		public:
+
+			DHTTable ();
+			~DHTTable ();
+
+			DHTNode * Insert (const IdentHash& h);
+			bool Remove (const IdentHash& h);
+			IdentHash * FindClosest (const IdentHash& h);
+			
+			void Print (std::stringstream& s);	
+			size_t GetSize () const { return m_Size; };
+			
+		private:
+
+			DHTNode * Insert (IdentHash * h, DHTNode * root, int level); // recursive
+			bool Remove (const IdentHash& h, DHTNode * root, int level);
+			IdentHash * FindClosest (const IdentHash& h, DHTNode * root, int level);
+			void Print (std::stringstream& s, DHTNode * root, int level);	
+			
+		private:
+
+			DHTNode * m_Root;
+			size_t m_Size;
+	};	
+}
+}
+
+#endif