230 lines
6.4 KiB
C++
230 lines
6.4 KiB
C++
/*
|
|
|
|
Copyright (c) 2006-2014, Arvid Norberg
|
|
All rights reserved.
|
|
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions
|
|
are met:
|
|
|
|
* Redistributions of source code must retain the above copyright
|
|
notice, this list of conditions and the following disclaimer.
|
|
* Redistributions in binary form must reproduce the above copyright
|
|
notice, this list of conditions and the following disclaimer in
|
|
the documentation and/or other materials provided with the distribution.
|
|
* Neither the name of the author nor the names of its
|
|
contributors may be used to endorse or promote products derived
|
|
from this software without specific prior written permission.
|
|
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
*/
|
|
|
|
#include <algorithm>
|
|
#include <ctime>
|
|
#include <boost/crc.hpp>
|
|
|
|
#include "libtorrent/kademlia/node_id.hpp"
|
|
#include "libtorrent/kademlia/node_entry.hpp"
|
|
#include "libtorrent/hasher.hpp"
|
|
#include "libtorrent/assert.hpp"
|
|
#include "libtorrent/broadcast_socket.hpp" // for is_local et.al
|
|
#include "libtorrent/socket_io.hpp" // for hash_address
|
|
#include "libtorrent/random.hpp" // for random
|
|
#include "libtorrent/hasher.hpp" // for hasher
|
|
|
|
namespace libtorrent { namespace dht
|
|
{
|
|
|
|
// returns the distance between the two nodes
|
|
// using the kademlia XOR-metric
|
|
node_id distance(node_id const& n1, node_id const& n2)
|
|
{
|
|
node_id ret;
|
|
node_id::iterator k = ret.begin();
|
|
for (node_id::const_iterator i = n1.begin(), j = n2.begin()
|
|
, end(n1.end()); i != end; ++i, ++j, ++k)
|
|
{
|
|
*k = *i ^ *j;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
// returns true if: distance(n1, ref) < distance(n2, ref)
|
|
bool compare_ref(node_id const& n1, node_id const& n2, node_id const& ref)
|
|
{
|
|
for (node_id::const_iterator i = n1.begin(), j = n2.begin()
|
|
, k = ref.begin(), end(n1.end()); i != end; ++i, ++j, ++k)
|
|
{
|
|
boost::uint8_t lhs = (*i ^ *k);
|
|
boost::uint8_t rhs = (*j ^ *k);
|
|
if (lhs < rhs) return true;
|
|
if (lhs > rhs) return false;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// returns n in: 2^n <= distance(n1, n2) < 2^(n+1)
|
|
// useful for finding out which bucket a node belongs to
|
|
int distance_exp(node_id const& n1, node_id const& n2)
|
|
{
|
|
int byte = node_id::size - 1;
|
|
for (node_id::const_iterator i = n1.begin(), j = n2.begin()
|
|
, end(n1.end()); i != end; ++i, ++j, --byte)
|
|
{
|
|
TORRENT_ASSERT(byte >= 0);
|
|
boost::uint8_t t = *i ^ *j;
|
|
if (t == 0) continue;
|
|
// we have found the first non-zero byte
|
|
// return the bit-number of the first bit
|
|
// that differs
|
|
int bit = byte * 8;
|
|
for (int b = 7; b >= 0; --b)
|
|
if (t >= (1 << b)) return bit + b;
|
|
return bit;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
node_id generate_id_impl(address const& ip_, boost::uint32_t r)
|
|
{
|
|
boost::uint8_t* ip = 0;
|
|
|
|
const static boost::uint8_t v4mask[] = { 0x03, 0x0f, 0x3f, 0xff };
|
|
const static boost::uint8_t v6mask[] = { 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff };
|
|
boost::uint8_t const* mask = 0;
|
|
int num_octets = 0;
|
|
|
|
address_v4::bytes_type b4;
|
|
#if TORRENT_USE_IPV6
|
|
address_v6::bytes_type b6;
|
|
if (ip_.is_v6())
|
|
{
|
|
b6 = ip_.to_v6().to_bytes();
|
|
ip = &b6[0];
|
|
num_octets = 8;
|
|
mask = v6mask;
|
|
}
|
|
else
|
|
#endif
|
|
{
|
|
b4 = ip_.to_v4().to_bytes();
|
|
ip = &b4[0];
|
|
num_octets = 4;
|
|
mask = v4mask;
|
|
}
|
|
|
|
for (int i = 0; i < num_octets; ++i)
|
|
ip[i] &= mask[i];
|
|
|
|
ip[0] |= (r & 0x7) << 5;
|
|
|
|
// this is the crc32c (Castagnoli) polynomial
|
|
// TODO: 2 this could be optimized if SSE 4.2 is
|
|
// available. It could also be optimized given
|
|
// that we have a fixed length
|
|
boost::crc_optimal<32, 0x1EDC6F41, 0xFFFFFFFF, 0xFFFFFFFF, true, true> crc;
|
|
crc.process_block(ip, ip + num_octets);
|
|
boost::uint32_t c = crc.checksum();
|
|
node_id id;
|
|
|
|
id[0] = (c >> 24) & 0xff;
|
|
id[1] = (c >> 16) & 0xff;
|
|
id[2] = ((c >> 8) & 0xf8) | (random() & 0x7);
|
|
|
|
for (int i = 3; i < 19; ++i) id[i] = random() & 0xff;
|
|
id[19] = r & 0xff;
|
|
|
|
return id;
|
|
}
|
|
|
|
static boost::uint32_t secret = 0;
|
|
|
|
void make_id_secret(node_id& in)
|
|
{
|
|
if (secret == 0) secret = (random() % 0xfffffffe) + 1;
|
|
|
|
boost::uint32_t rand = random();
|
|
|
|
// generate the last 4 bytes as a "signature" of the previous 4 bytes. This
|
|
// lets us verify whether a hash came from this function or not in the future.
|
|
hasher h((char*)&secret, 4);
|
|
h.update((char*)&rand, 4);
|
|
sha1_hash secret_hash = h.final();
|
|
memcpy(&in[20-4], &secret_hash[0], 4);
|
|
memcpy(&in[20-8], &rand, 4);
|
|
}
|
|
|
|
node_id generate_random_id()
|
|
{
|
|
char r[20];
|
|
for (int i = 0; i < 20; ++i) r[i] = random() & 0xff;
|
|
return hasher(r, 20).final();
|
|
}
|
|
|
|
node_id generate_secret_id()
|
|
{
|
|
node_id ret = generate_random_id();
|
|
make_id_secret(ret);
|
|
return ret;
|
|
}
|
|
|
|
bool verify_secret_id(node_id const& nid)
|
|
{
|
|
if (secret == 0) return false;
|
|
|
|
hasher h((char*)&secret, 4);
|
|
h.update((char const*)&nid[20-8], 4);
|
|
sha1_hash secret_hash = h.final();
|
|
return memcmp(&nid[20-4], &secret_hash[0], 4) == 0;
|
|
}
|
|
|
|
// verifies whether a node-id matches the IP it's used from
|
|
// returns true if the node-id is OK coming from this source
|
|
// and false otherwise.
|
|
bool verify_id(node_id const& nid, address const& source_ip)
|
|
{
|
|
// no need to verify local IPs, they would be incorrect anyway
|
|
if (is_local(source_ip)) return true;
|
|
|
|
node_id h = generate_id_impl(source_ip, nid[19]);
|
|
return nid[0] == h[0] && nid[1] == h[1] && (nid[2] & 0xf8) == (h[2] & 0xf8);
|
|
}
|
|
|
|
node_id generate_id(address const& ip)
|
|
{
|
|
return generate_id_impl(ip, random());
|
|
}
|
|
|
|
bool matching_prefix(node_entry const& n, int mask, int prefix, int bucket_index)
|
|
{
|
|
node_id id = n.id;
|
|
id <<= bucket_index + 1;
|
|
return (id[0] & mask) == prefix;
|
|
}
|
|
|
|
node_id generate_prefix_mask(int bits)
|
|
{
|
|
TORRENT_ASSERT(bits >= 0);
|
|
TORRENT_ASSERT(bits <= 160);
|
|
node_id mask(0);
|
|
int b = 0;
|
|
for (; b < bits - 7; b += 8) mask[b/8] |= 0xff;
|
|
if (bits < 160) mask[b/8] |= (0xff << (8 - (bits&7))) & 0xff;
|
|
return mask;
|
|
}
|
|
|
|
} } // namespace libtorrent::dht
|
|
|