// Handle getheaders protocol command // https://en.bitcoin.it/wiki/Protocol_specification#getheaders func (c *OneConnection) GetHeaders(pl []byte) { h2get, hashstop, e := parseLocatorsPayload(pl) if e != nil || hashstop == nil { println("GetHeaders: error parsing payload from", c.PeerAddr.Ip()) c.DoS("BadGetHdrs") return } if common.DebugLevel > 1 { println("GetHeaders", len(h2get), hashstop.String()) } var best_block, last_block *chain.BlockTreeNode common.BlockChain.BlockIndexAccess.Lock() if len(h2get) > 0 { for i := range h2get { if bl, ok := common.BlockChain.BlockIndex[h2get[i].BIdx()]; ok { if best_block == nil || bl.Height > best_block.Height { best_block = bl } } } } else { best_block = common.BlockChain.BlockIndex[hashstop.BIdx()] } last_block = common.BlockChain.BlockTreeEnd common.BlockChain.BlockIndexAccess.Unlock() var resp []byte var cnt uint32 for cnt < 2000 { best_block = best_block.FindPathTo(last_block) if best_block == nil { break } resp = append(resp, append(best_block.BlockHeader[:], 0)...) // 81st byte is always zero cnt++ } out := new(bytes.Buffer) btc.WriteVlen(out, uint64(cnt)) out.Write(resp) c.SendRawMsg("headers", out.Bytes()) return }