BlockInfo?GetFromList(IPeer peer, BitField bitfield, IList <int> pieces)
{
if (!peer.SupportsFastPeer || !ClientEngine.SupportsFastPeer)
{
return(null);
}
for (int i = 0; i < pieces.Count; i++)
{
int index = pieces[i];
// A peer should only suggest a piece he has, but just in case.
if (index >= bitfield.Length || !bitfield[index] || AlreadyRequested(index))
{
continue;
}
pieces.RemoveAt(i);
var p = new Piece(index, TorrentData.BytesPerPiece(index));
requests.Add(p);
return(p.Blocks[0].CreateRequest(peer));
}
return(null);
}
IList <BlockInfo> GetStandardRequest(IPeer peer, BitField current, int startIndex, int endIndex, int count)
{
int piecesNeeded = (count * Piece.BlockSize) / TorrentData.PieceLength;
if ((count * Piece.BlockSize) % TorrentData.PieceLength != 0)
{
piecesNeeded++;
}
int checkIndex = CanRequest(current, startIndex, endIndex, ref piecesNeeded);
// Nothing to request.
if (checkIndex == -1)
{
return(null);
}
var bundle = new List <BlockInfo> (count);
for (int i = 0; bundle.Count < count && i < piecesNeeded; i++)
{
// Request the piece
var p = new Piece(checkIndex + i, TorrentData.BytesPerPiece(checkIndex + i));
requests.Add(p);
for (int j = 0; j < p.Blocks.Length && bundle.Count < count; j++)
{
bundle.Add(p.Blocks[j].CreateRequest(peer));
}
}
return(bundle);
}
BlockInfo?ContinueExistingRequest(IPeer peer, int startIndex, int endIndex, int maxDuplicateRequests, bool allowAbandoned, bool allowAny)
{
for (int req = 0; req < requests.Count; req++)
{
Piece p = requests[req];
int index = p.Index;
if (p.AllBlocksRequested || index < startIndex || index > endIndex || !peer.BitField[index])
{
continue;
}
// For each piece that was assigned to this peer, try to request a block from it
// A piece is 'assigned' to a peer if he is the first person to request a block from that piece
if (allowAny || (allowAbandoned && p.Abandoned) || peer == p.Blocks[0].RequestedOff)
{
for (int i = 0; i < p.BlockCount; i++)
{
if (!p.Blocks[i].Received && !p.Blocks[i].Requested)
{
return(p.Blocks[i].CreateRequest(peer));
}
}
}
}
// If all blocks have been requested at least once and we're allowed more than 1 request then
// let's try and issue a duplicate!
for (int duplicate = 1; duplicate < maxDuplicateRequests; duplicate++)
{
for (int req = 0; req < requests.Count; req++)
{
Piece primaryPiece = requests[req];
if (primaryPiece.Index < startIndex || primaryPiece.Index > endIndex || !peer.BitField[primaryPiece.Index])
{
continue;
}
if (!duplicates.TryGetValue(primaryPiece.Index, out List <Piece> extraPieces))
{
duplicates[primaryPiece.Index] = extraPieces = new List <Piece> ();
}
if (extraPieces.Count < duplicate)
{
var newPiece = new Piece(primaryPiece.Index, TorrentData.BytesPerPiece(primaryPiece.Index));
for (int i = 0; i < primaryPiece.BlockCount; i++)
{
if (primaryPiece.Blocks[i].Received)
{
newPiece.Blocks[i].TrySetReceived(primaryPiece.Blocks[i].RequestedOff);
}
}
extraPieces.Add(newPiece);
}
for (int extraPieceIndex = 0; extraPieceIndex < extraPieces.Count; extraPieceIndex++)
{
var extraPiece = extraPieces[extraPieceIndex];
for (int i = 0; i < extraPiece.BlockCount; i++)
{
if (!extraPiece.Blocks[i].Requested && !HasAlreadyRequestedBlock(primaryPiece, extraPieces, peer, i))
{
return(extraPiece.Blocks[i].CreateRequest(peer));
}
}
}
}
}
// If we get here it means all the blocks in the pieces being downloaded by the peer are already requested
return(null);
}