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initial commit for Kademlia DHT
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libi2pd/KadDHT.cpp
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238
libi2pd/KadDHT.cpp
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/*
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* Copyright (c) 2023, The PurpleI2P Project
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*
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* This file is part of Purple i2pd project and licensed under BSD3
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*
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* See full license text in LICENSE file at top of project tree
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*
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*/
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#include "KadDHT.h"
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namespace i2p
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{
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namespace data
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{
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DHTNode::DHTNode ():
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zero (nullptr), one (nullptr), hash (nullptr)
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{
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}
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DHTNode::~DHTNode ()
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{
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if (zero) delete zero;
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if (one) delete one;
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if (hash) delete hash;
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}
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void DHTNode::MoveHashUp (bool fromOne)
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{
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DHTNode *& side = fromOne ? one : zero;
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if (side)
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{
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if (hash) delete hash; // shouldn't happen
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hash = side->hash;
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side->hash = nullptr;
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delete side;
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side = nullptr;
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}
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}
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DHTTable::DHTTable ():
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m_Size (0)
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{
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m_Root = new DHTNode;
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}
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DHTTable::~DHTTable ()
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{
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delete m_Root;
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}
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DHTNode * DHTTable::Insert (const IdentHash& h)
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{
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return Insert (new IdentHash (h), m_Root, 0);
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}
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DHTNode * DHTTable::Insert (IdentHash * h, DHTNode * root, int level)
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{
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if (root->hash)
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{
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if (*(root->hash) == *h)
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{
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delete h;
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return root;
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}
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auto h2 = root->hash;
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root->hash = nullptr; m_Size--;
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int bit1, bit2;
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do
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{
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bit1 = h->GetBit (level);
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bit2 = h2->GetBit (level);
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if (bit1 == bit2)
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{
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if (bit1)
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{
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if (root->one) return nullptr; // someting wrong
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root->one = new DHTNode;
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root = root->one;
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}
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else
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{
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if (root->zero) return nullptr; // someting wrong
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root->zero = new DHTNode;
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root = root->zero;
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}
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level++;
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}
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}
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while (bit1 == bit2);
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if (!root->zero)
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root->zero = new DHTNode;
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if (!root->one)
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root->one = new DHTNode;
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if (bit1)
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{
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Insert (h2, root->zero, level + 1);
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return Insert (h, root->one, level + 1);
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}
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else
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{
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Insert (h2, root->one, level + 1);
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return Insert (h, root->zero, level + 1);
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}
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}
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else
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{
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if (!root->zero && !root->one)
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{
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root->hash = h; m_Size++;
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return root;
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}
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int bit = h->GetBit (level);
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if (bit)
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{
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if (!root->one)
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root->one = new DHTNode;
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return Insert (h, root->one, level + 1);
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}
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else
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{
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if (!root->zero)
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root->zero = new DHTNode;
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return Insert (h, root->zero, level + 1);
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}
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}
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return nullptr;
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}
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bool DHTTable::Remove (const IdentHash& h)
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{
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return Remove (h, m_Root, 0);
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}
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bool DHTTable::Remove (const IdentHash& h, DHTNode * root, int level)
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{
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if (root)
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{
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if (root->hash && *(root->hash) == h)
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{
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delete root->hash; root->hash = nullptr;
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m_Size--;
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return true;
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}
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int bit = h.GetBit (level);
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if (bit)
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{
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if (root->one && Remove (h, root->one, level + 1))
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{
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if (root->one->IsEmpty ())
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{
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delete root->one;
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root->one = nullptr;
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if (root->zero && root->zero->hash)
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root->MoveHashUp (false);
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}
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else if (root->one->hash && !root->zero)
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root->MoveHashUp (true);
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return true;
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}
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}
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else
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{
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if (root->zero && Remove (h, root->zero, level + 1))
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{
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if (root->zero->IsEmpty ())
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{
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delete root->zero;
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root->zero = nullptr;
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if (root->one && root->one->hash)
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root->MoveHashUp (true);
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}
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else if (root->zero->hash && !root->one)
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root->MoveHashUp (false);
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return true;
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}
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}
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}
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return false;
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}
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IdentHash * DHTTable::FindClosest (const IdentHash& h)
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{
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return FindClosest (h, m_Root, 0);
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}
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IdentHash * DHTTable::FindClosest (const IdentHash& h, DHTNode * root, int level)
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{
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if (root->hash) return root->hash;
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int bit = h.GetBit (level);
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if (bit)
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{
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if (root->one)
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return FindClosest (h, root->one, level + 1);
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if (root->zero)
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return FindClosest (h, root->zero, level + 1);
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}
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else
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{
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if (root->zero)
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return FindClosest (h, root->zero, level + 1);
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if (root->one)
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return FindClosest (h, root->one, level + 1);
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}
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return nullptr;
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}
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void DHTTable::Print (std::stringstream& s)
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{
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Print (s, m_Root, 0);
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}
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void DHTTable::Print (std::stringstream& s, DHTNode * root, int level)
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{
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if (!root) return;
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s << std::string (level, '-');
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if (root->hash)
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{
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if (!root->zero && !root->one)
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s << '>' << GetIdentHashAbbreviation (*(root->hash));
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else
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s << "error";
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}
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s << std::endl;
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if (root->zero)
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{
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s << std::string (level, '-') << "0" << std::endl;
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Print (s, root->zero, level + 1);
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}
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if (root->one)
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{
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s << std::string (level, '-') << "1" << std::endl;
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Print (s, root->one, level + 1);
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}
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}
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}
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}
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64
libi2pd/KadDHT.h
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64
libi2pd/KadDHT.h
Normal file
@ -0,0 +1,64 @@
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/*
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* Copyright (c) 2023, The PurpleI2P Project
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*
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* This file is part of Purple i2pd project and licensed under BSD3
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*
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* See full license text in LICENSE file at top of project tree
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*
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*/
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#ifndef KADDHT_H__
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#define KADDHT_H__
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#include <memory>
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#include <sstream>
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#include "Identity.h"
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// Kademlia DHT (XOR distance)
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namespace i2p
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{
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namespace data
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{
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struct DHTNode
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{
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DHTNode * zero, * one;
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IdentHash * hash;
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DHTNode ();
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~DHTNode ();
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bool IsEmpty () const { return !zero && !one && !hash; };
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void MoveHashUp (bool fromOne);
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};
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class DHTTable
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{
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public:
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DHTTable ();
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~DHTTable ();
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DHTNode * Insert (const IdentHash& h);
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bool Remove (const IdentHash& h);
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IdentHash * FindClosest (const IdentHash& h);
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void Print (std::stringstream& s);
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size_t GetSize () const { return m_Size; };
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private:
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DHTNode * Insert (IdentHash * h, DHTNode * root, int level); // recursive
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bool Remove (const IdentHash& h, DHTNode * root, int level);
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IdentHash * FindClosest (const IdentHash& h, DHTNode * root, int level);
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void Print (std::stringstream& s, DHTNode * root, int level);
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private:
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DHTNode * m_Root;
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size_t m_Size;
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};
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}
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}
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#endif
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