src/kademlia/traversal_algorithm.cpp

   1 /*
   2
   3 Copyright (c) 2006, Arvid Norberg & Daniel Wallin
   4 All rights reserved.
   5
   6 Redistribution and use in source and binary forms, with or without
   7 modification, are permitted provided that the following conditions
   8 are met:
   9
  10     * Redistributions of source code must retain the above copyright
  11       notice, this list of conditions and the following disclaimer.
  12     * Redistributions in binary form must reproduce the above copyright
  13       notice, this list of conditions and the following disclaimer in
  14       the documentation and/or other materials provided with the distribution.
  15     * Neither the name of the author nor the names of its
  16       contributors may be used to endorse or promote products derived
  17       from this software without specific prior written permission.
  18
  19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  20 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  23 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29 POSSIBILITY OF SUCH DAMAGE.
  30
  31 */
  32
  33 #include "libtorrent/pch.hpp"
  34
  35 #include <libtorrent/kademlia/traversal_algorithm.hpp>
  36 #include <libtorrent/kademlia/routing_table.hpp>
  37 #include <libtorrent/kademlia/rpc_manager.hpp>
  38
  39 #include <boost/bind.hpp>
  40
  41 using boost::bind;
  42
  43 namespace libtorrent { namespace dht
  44 {
  45 #ifdef TORRENT_DHT_VERBOSE_LOGGING
  46 TORRENT_DEFINE_LOG(traversal)
  47 #endif
  48
  49 void traversal_algorithm::add_entry(node_id const& id, udp::endpoint addr, unsigned char flags)
  50 {
  51         if (m_failed.find(addr) != m_failed.end()) return;
  52
  53         result entry(id, addr, flags);
  54         if (entry.id.is_all_zeros())
  55         {
  56                 entry.id = generate_id();
  57                 entry.flags |= result::no_id;
  58         }
  59
  60         std::vector<result>::iterator i = std::lower_bound(
  61                 m_results.begin()
  62                 , m_results.end()
  63                 , entry
  64                 , bind(
  65                         compare_ref
  66                         , bind(&result::id, _1)
  67                         , bind(&result::id, _2)
  68                         , m_target
  69                 )
  70         );
  71
  72         if (i == m_results.end() || i->id != id)
  73         {
  74                 TORRENT_ASSERT(std::find_if(m_results.begin(), m_results.end()
  75                         , bind(&result::id, _1) == id) == m_results.end());
  76 #ifdef TORRENT_DHT_VERBOSE_LOGGING
  77                 TORRENT_LOG(traversal) << "adding result: " << id << " " << addr;
  78 #endif
  79                 m_results.insert(i, entry);
  80         }
  81 }
  82
  83 boost::pool<>& traversal_algorithm::allocator() const
  84 {
  85         return m_rpc.allocator();
  86 }
  87
  88 void traversal_algorithm::traverse(node_id const& id, udp::endpoint addr)
  89 {
  90 #ifdef TORRENT_DHT_VERBOSE_LOGGING
  91         if (id.is_all_zeros())
  92         TORRENT_LOG(traversal) << time_now_string() << " WARNING: node returned a list which included a node with id 0";
  93 #endif
  94         add_entry(id, addr, 0);
  95 }
  96
  97 void traversal_algorithm::finished(node_id const& id)
  98 {
  99         --m_invoke_count;
 100         add_requests();
 101         if (m_invoke_count == 0) done();
 102 }
 103
 104 // prevent request means that the total number of requests has
 105 // overflown. This query failed because it was the oldest one.
 106 // So, if this is true, don't make another request
 107 void traversal_algorithm::failed(node_id const& id, bool prevent_request)
 108 {
 109         m_invoke_count--;
 110
 111         TORRENT_ASSERT(!id.is_all_zeros());
 112         std::vector<result>::iterator i = std::find_if(
 113                 m_results.begin()
 114                 , m_results.end()
 115                 , bind(
 116                         std::equal_to<node_id>()
 117                         , bind(&result::id, _1)
 118                         , id
 119                 )
 120         );
 121
 122         TORRENT_ASSERT(i != m_results.end());
 123
 124         if (i != m_results.end())
 125         {
 126                 TORRENT_ASSERT(i->flags & result::queried);
 127                 m_failed.insert(i->addr);
 128 #ifdef TORRENT_DHT_VERBOSE_LOGGING
 129                 TORRENT_LOG(traversal) << "failed: " << i->id << " " << i->addr;
 130 #endif
 131                 // don't tell the routing table about
 132                 // node ids that we just generated ourself
 133                 if ((i->flags & result::no_id) == 0)
 134                         m_table.node_failed(id);
 135                 m_results.erase(i);
 136         }
 137         if (prevent_request)
 138         {
 139                 --m_branch_factor;
 140                 if (m_branch_factor <= 0) m_branch_factor = 1;
 141         }
 142         add_requests();
 143         if (m_invoke_count == 0) done();
 144 }
 145
 146 namespace
 147 {
 148         bool bitwise_nand(unsigned char lhs, unsigned char rhs)
 149         {
 150                 return (lhs & rhs) == 0;
 151         }
 152 }
 153
 154 void traversal_algorithm::add_requests()
 155 {
 156         while (m_invoke_count < m_branch_factor)
 157         {
 158                 // Find the first node that hasn't already been queried.
 159                 // TODO: Better heuristic
 160                 std::vector<result>::iterator i = std::find_if(
 161                         m_results.begin()
 162                         , last_iterator()
 163                         , bind(
 164                                 &bitwise_nand
 165                                 , bind(&result::flags, _1)
 166                                 , (unsigned char)result::queried
 167                         )
 168                 );
 169 #ifdef TORRENT_DHT_VERBOSE_LOGGING
 170                 TORRENT_LOG(traversal) << "nodes left (" << this << "): " << (last_iterator() - i);
 171 #endif
 172
 173                 if (i == last_iterator()) break;
 174
 175                 try
 176                 {
 177                         invoke(i->id, i->addr);
 178                         ++m_invoke_count;
 179                         i->flags |= result::queried;
 180                 }
 181                 catch (std::exception& e) {}
 182         }
 183 }
 184
 185 std::vector<traversal_algorithm::result>::iterator traversal_algorithm::last_iterator()
 186 {
 187         return (int)m_results.size() >= m_max_results ?
 188                 m_results.begin() + m_max_results
 189                 : m_results.end();
 190 }
 191
 192 } } // namespace libtorrent::dht
 193