| 1 | #ifndef __MERKLE_TREE_HH__␊ |
| 2 | #define __MERKLE_TREE_HH__␊ |
| 3 | ␊ |
| 4 | // Copyright (C) 2004 Graydon Hoare <graydon@pobox.com>␊ |
| 5 | //␊ |
| 6 | // This program is made available under the GNU GPL version 2.0 or␊ |
| 7 | // greater. See the accompanying file COPYING for details.␊ |
| 8 | //␊ |
| 9 | // This program is distributed WITHOUT ANY WARRANTY; without even the␊ |
| 10 | // implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR␊ |
| 11 | // PURPOSE.␊ |
| 12 | ␊ |
| 13 | #include <map>␊ |
| 14 | #include <set>␊ |
| 15 | ␊ |
| 16 | #include <boost/shared_ptr.hpp>␊ |
| 17 | #include <boost/dynamic_bitset.hpp>␊ |
| 18 | ␊ |
| 19 | #include "vector.hh"␊ |
| 20 | #include "vocab.hh"␊ |
| 21 | #include "transforms.hh"␊ |
| 22 | #include "hash_map.hh"␊ |
| 23 | ␊ |
| 24 | // This file contains data structures and functions for managing merkle␊ |
| 25 | // trees. A merkle tree is, conceptually, a general recursive construction␊ |
| 26 | // whereby a range of K data elements is divided up into buckets. Each␊ |
| 27 | // bucket is then hashed, and the hash values of the buckets at level N of␊ |
| 28 | // the tree are used as data elements held in buckets at level N-1. At␊ |
| 29 | // level 0 there is only one bucket.␊ |
| 30 | //␊ |
| 31 | // The result is a tree in which each node has J "slots", each of which␊ |
| 32 | // summarizes (as a hashcode) the entire subtree beneath it. this makes a␊ |
| 33 | // pair of merkle trees amenable to setwise operations such as union or␊ |
| 34 | // difference while only inspecting D*log_base_J(K) nodes where D is the␊ |
| 35 | // number of differences between trees.␊ |
| 36 | //␊ |
| 37 | // We build merkle trees over a few collections of objects in our database␊ |
| 38 | // and use these to synchronize with remote hosts. See netsync.{cc,hh} and␊ |
| 39 | // refiner.{cc,hh} for more details.␊ |
| 40 | ␊ |
| 41 | typedef enum␊ |
| 42 | {␊ |
| 43 | file_item = 2,␊ |
| 44 | key_item = 3,␊ |
| 45 | revision_item = 4,␊ |
| 46 | cert_item = 5,␊ |
| 47 | epoch_item = 6␊ |
| 48 | }␊ |
| 49 | netcmd_item_type;␊ |
| 50 | ␊ |
| 51 | void netcmd_item_type_to_string(netcmd_item_type t, std::string & typestr);␊ |
| 52 | ␊ |
| 53 | typedef enum␊ |
| 54 | {␊ |
| 55 | empty_state,␊ |
| 56 | leaf_state,␊ |
| 57 | subtree_state␊ |
| 58 | }␊ |
| 59 | slot_state;␊ |
| 60 | ␊ |
| 61 | struct merkle_node␊ |
| 62 | {␊ |
| 63 | size_t level;␊ |
| 64 | boost::dynamic_bitset<unsigned char> pref;␊ |
| 65 | size_t total_num_leaves;␊ |
| 66 | boost::dynamic_bitset<unsigned char> bitmap;␊ |
| 67 | std::vector<id> slots;␊ |
| 68 | netcmd_item_type type;␊ |
| 69 | ␊ |
| 70 | merkle_node();␊ |
| 71 | bool operator==(merkle_node const & other) const;␊ |
| 72 | void check_invariants() const;␊ |
| 73 | ␊ |
| 74 | void get_raw_prefix(prefix & pref) const;␊ |
| 75 | void get_hex_prefix(hexenc<prefix> & hpref) const;␊ |
| 76 | ␊ |
| 77 | void get_raw_slot(size_t slot, id & val) const;␊ |
| 78 | void get_hex_slot(size_t slot, hexenc<id> & val) const;␊ |
| 79 | ␊ |
| 80 | void set_raw_slot(size_t slot, id const & val);␊ |
| 81 | void set_hex_slot(size_t slot, hexenc<id> const & val);␊ |
| 82 | ␊ |
| 83 | void extended_prefix(size_t slot, boost::dynamic_bitset<unsigned char> & extended) const;␊ |
| 84 | void extended_raw_prefix(size_t slot, prefix & extended) const;␊ |
| 85 | void extended_hex_prefix(size_t slot, hexenc<prefix> & extended) const;␊ |
| 86 | ␊ |
| 87 | slot_state get_slot_state(size_t n) const;␊ |
| 88 | void set_slot_state(size_t n, slot_state st);␊ |
| 89 | };␊ |
| 90 | ␊ |
| 91 | typedef boost::shared_ptr<merkle_node> merkle_ptr;␊ |
| 92 | ␊ |
| 93 | typedef std::pair<prefix,size_t> merkle_node_id;␊ |
| 94 | namespace hashmap {␊ |
| 95 | template<>␊ |
| 96 | struct hash<merkle_node_id>␊ |
| 97 | {␊ |
| 98 | hash<std::string> sh;␊ |
| 99 | size_t operator()(merkle_node_id const & m) const␊ |
| 100 | {␊ |
| 101 | return sh(m.first()) + m.second;␊ |
| 102 | }␊ |
| 103 | };␊ |
| 104 | }␊ |
| 105 | typedef hashmap::hash_map<merkle_node_id, merkle_ptr> merkle_table;␊ |
| 106 | ␊ |
| 107 | ␊ |
| 108 | size_t prefix_length_in_bits(size_t level);␊ |
| 109 | size_t prefix_length_in_bytes(size_t level);␊ |
| 110 | void write_node(merkle_node const & in, std::string & outbuf);␊ |
| 111 | void read_node(std::string const & inbuf, size_t & pos, merkle_node & out);␊ |
| 112 | ␊ |
| 113 | std::string raw_sha1(std::string const & in);␊ |
| 114 | ␊ |
| 115 | ␊ |
| 116 | bool␊ |
| 117 | locate_item(merkle_table & table,␊ |
| 118 | id const & val,␊ |
| 119 | size_t & slotnum,␊ |
| 120 | merkle_ptr & mp);␊ |
| 121 | ␊ |
| 122 | ␊ |
| 123 | void␊ |
| 124 | pick_slot_and_prefix_for_value(id const & val,␊ |
| 125 | size_t level,␊ |
| 126 | size_t & slotnum,␊ |
| 127 | boost::dynamic_bitset<unsigned char> & pref);␊ |
| 128 | ␊ |
| 129 | // Collect the items inside a subtree.␊ |
| 130 | ␊ |
| 131 | void␊ |
| 132 | collect_items_in_subtree(merkle_table & tab,␊ |
| 133 | prefix const & pref,␊ |
| 134 | size_t level,␊ |
| 135 | std::set<id> & items);␊ |
| 136 | ␊ |
| 137 | // Insert an item into a tree.␊ |
| 138 | ␊ |
| 139 | void␊ |
| 140 | insert_into_merkle_tree(merkle_table & tab,␊ |
| 141 | netcmd_item_type type,␊ |
| 142 | id const & leaf,␊ |
| 143 | size_t level);␊ |
| 144 | ␊ |
| 145 | inline void␊ |
| 146 | insert_into_merkle_tree(merkle_table & tab,␊ |
| 147 | netcmd_item_type type,␊ |
| 148 | hexenc<id> const & hex_leaf,␊ |
| 149 | size_t level)␊ |
| 150 | {␊ |
| 151 | id leaf;␊ |
| 152 | decode_hexenc(hex_leaf, leaf);␊ |
| 153 | insert_into_merkle_tree(tab, type, leaf, level);␊ |
| 154 | }␊ |
| 155 | ␊ |
| 156 | // Recalculate the hashes in the given tree. Must be called after␊ |
| 157 | // insert_into_merkle_tree, and before using tree (but you can batch up␊ |
| 158 | // multiple calls to insert_into_merkle_tree and then only call this once).␊ |
| 159 | ␊ |
| 160 | id␊ |
| 161 | recalculate_merkle_codes(merkle_table & tab,␊ |
| 162 | prefix const & pref,␊ |
| 163 | size_t level);␊ |
| 164 | ␊ |
| 165 | // Local Variables:␊ |
| 166 | // mode: C++␊ |
| 167 | // fill-column: 76␊ |
| 168 | // c-file-style: "gnu"␊ |
| 169 | // indent-tabs-mode: nil␊ |
| 170 | // End:␊ |
| 171 | // vim: et:sw=2:sts=2:ts=2:cino=>2s,{s,\:s,+s,t0,g0,^-2,e-2,n-2,p2s,(0,=s:␊ |
| 172 | ␊ |
| 173 | #endif // __MERKLE_TREE_HH__␊ |
