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- Enabled multi-tunneling by consistently perturbating partial tunnel id in TRs.

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This causes tunnels with a different route to have different ids and therefore
  coexist as different sources for a given transfer.
  This should cause file transfers to have more tunnels and therefore a better balance
  of bandwidth over intermediate peers. This needs to be evaluated on a large scale network.

- Cleaned some unused code.



git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@6740 b45a01b8-16f6-495d-af2f-9b41ad6348cc
This commit is contained in:
csoler 2013-09-15 19:05:04 +00:00
parent d127d36131
commit 81a4523434
2 changed files with 19 additions and 50 deletions
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67
libretroshare/src/turtle/p3turtle.cc
View File

@ -699,14 +699,14 @@ uint32_t p3turtle::generateRandomRequestId()
return RSRandom::random_u32() ;
}
uint32_t p3turtle::generatePersonalFilePrint(const TurtleFileHash& hash,bool b)
uint32_t p3turtle::generatePersonalFilePrint(const TurtleFileHash& hash,uint32_t seed,bool b)
{
// whatever cooking from the file hash and OwnId that cannot be recovered.
// The only important thing is that the saem couple (hash,SSL id) produces the same tunnel
// id. The result uses a boolean to allow generating non symmetric tunnel ids.
std::string buff(hash + mLinkMgr->getOwnId()) ;
uint32_t res = 0 ;
uint32_t res = seed ;
uint32_t decal = 0 ;
for(int i=0;i<(int)buff.length();++i)
@ -1288,7 +1288,7 @@ TurtleRequestId p3turtle::diggTunnel(const TurtleFileHash& hash)
item->PeerId(mLinkMgr->getOwnId()) ;
item->file_hash = hash ;
item->request_id = id ;
item->partial_tunnel_id = generatePersonalFilePrint(hash,true) ;
item->partial_tunnel_id = generatePersonalFilePrint(hash,_random_bias,true) ;
item->depth = 0 ;
// send it
@ -1340,13 +1340,6 @@ void p3turtle::handleTunnelRequest(RsTurtleOpenTunnelItem *item)
#ifdef P3TURTLE_DEBUG
std::cerr << "Forwarding probability: depth=" << item->depth << ", distance to max speed=" << distance_to_maximum << ", corrected=" << corrected_distance << ", prob.=" << forward_probability << std::endl;
#endif
// if(forward_probability < 0.1)
// {
//#ifdef P3TURTLE_DEBUG
// std::cerr << "Dropped packet!" << std::endl;
//#endif
// return ;
// }
}
// If the item contains an already handled tunnel request, give up. This
@ -1363,44 +1356,6 @@ void p3turtle::handleTunnelRequest(RsTurtleOpenTunnelItem *item)
{
#ifdef P3TURTLE_DEBUG
std::cerr << " This is a bouncing request. Ignoring and deleting item." << std::endl ;
#endif
#ifdef SUSPENDED
// This trick allows to shorten tunnels, favoring tunnels of smallest length, with a bias that
// depends on a mix between a session-based constant and the tunnel partial id. This means
// that for a given couple of (source,hash), the optimisation always performs the same.
// overall, 80% tunnels are re-routed. The probability of a tunnel to have optimal length is
// thus 0.875^n where n is the length of the tunnel, supposing that it has 2 branching peers
// at each node. This makes:
// n probability
// 1 0.875
// 2 0.76
// 3 0.67
// 4 0.58
// 5 0.512
//
// The lower the probability, the higher the anonymity level.
//
if(it->second.depth > item->depth && ((item->partial_tunnel_id ^ _random_bias)&0x7)>0)
{
#ifdef P3TURTLE_DEBUG
std::cerr << " re-routing tunnel request. Item age difference = " << time(NULL)-it->second.time_stamp << std::endl;
std::cerr << " - old source: " << it->second.origin << ", old depth=" << it->second.depth << std::endl ;
std::cerr << " - new source: " << item->PeerId() << ", new depth=" << item->depth << std::endl ;
std::cerr << " - half id: " << (void*)it->first << std::endl ;
#endif
it->second.origin = item->PeerId() ;
it->second.depth = item->depth ;
// also update local_tunnels is this is an ending tunnel.
//
std::map<std::string,FileInfo>::const_iterator it = _outgoing_file_hashes.find(item->file_hash) ;
if(it != _outgoing_file_hashes.end())
for(std::map<TurtleTunnelId,TurtleTunnel>::iterator it2(_local_tunnels.begin());it2!=_local_tunnels.end();++it2)
if(it2->second.hash == item->file_hash)
it2->second.local_src = item->PeerId() ;
}
#endif
return ;
}
@ -1449,7 +1404,7 @@ void p3turtle::handleTunnelRequest(RsTurtleOpenTunnelItem *item)
RsTurtleTunnelOkItem *res_item = new RsTurtleTunnelOkItem ;
res_item->request_id = item->request_id ;
res_item->tunnel_id = item->partial_tunnel_id ^ generatePersonalFilePrint(item->file_hash,false) ;
res_item->tunnel_id = item->partial_tunnel_id ^ generatePersonalFilePrint(item->file_hash,_random_bias,false) ;
res_item->PeerId(item->PeerId()) ;
sendItem(res_item) ;
@ -1493,6 +1448,20 @@ void p3turtle::handleTunnelRequest(RsTurtleOpenTunnelItem *item)
bool random_bypass = (item->depth >= TURTLE_MAX_SEARCH_DEPTH && (((_random_bias ^ item->partial_tunnel_id)&0x7)==2)) ;
bool random_dshift = (item->depth == 1 && (((_random_bias ^ item->partial_tunnel_id)&0x7)==6)) ;
// Multi-tunneling trick: consistently perturbate the half-tunnel id:
// - the tunnel id will now be unique for a given route
// - allows a better balance of bandwidth for a given transfer
// - avoid the waste of items that get lost when re-routing a tunnel
#ifdef P3TURTLE_DEBUG
std::cerr << "Perturbating partial tunnel id. Original=" << std::hex << item->partial_tunnel_id ;
#endif
item->partial_tunnel_id = generatePersonalFilePrint(item->file_hash,item->partial_tunnel_id ^ _random_bias,true) ;
#ifdef P3TURTLE_DEBUG
std::cerr << " new=" << item->partial_tunnel_id << std::dec << std::endl;
#endif
if(item->depth < TURTLE_MAX_SEARCH_DEPTH || random_bypass)
{
std::list<std::string> onlineIds ;

2
libretroshare/src/turtle/p3turtle.h
View File

@ -314,7 +314,7 @@ class p3turtle: public p3Service, public RsTurtle, public p3Config
//--------------------------- Admin/Helper functions -------------------------//
/// Generates a cyphered combination of ownId() and file hash
uint32_t generatePersonalFilePrint(const TurtleFileHash&,bool) ;
uint32_t generatePersonalFilePrint(const TurtleFileHash&,uint32_t seed,bool) ;
/// Generates a random uint32_t number.
uint32_t generateRandomRequestId() ;