虛擬幣開發專題(山寨幣怎樣通過RPC命令實現區塊瀏覽器)
阿新 • • 發佈：2019-01-10
區塊鏈愛好者（QQ：53016353）
基本架構如下：
前端web基於或者REST實現，後端加一層mongodb/mysql等資料庫來代替單機leveldb做資料儲存
目的應該是：
1. 加速查詢
2. 做更高層的資料分析
3.做分散式資料庫
思考:
這些online的查詢固然可以方便我們的日常用， 那如何與相關應用整合呢? 我們是否可以通過簡單的rpc命令實現同等的效果?
有幾個用處：
1 . 大家都可以做自己的qukuai.com或blockchain.info的查詢：）
2. 整合RPC命令到自己的店鋪，收款後查詢用
3. 整合到錢包應用
4. 其他應用場景
cmd分析：
根據高度height查block hash
./bitcoin-cli getblockhash 19999
00000000ba36eb929dc90170a96ee3efb76cbebee0e0e5c4da9eb0b6e74d9124
2. 然後根據block hash查block 資訊
./bitcoin-cli getblock 00000000ba36eb929dc90170a96ee3efb76cbebee0e0e5c4da9eb0b6e74d9124
{
"hash" : "00000000ba36eb929dc90170a96ee3efb76cbebee0e0e5c4da9eb0b6e74d9124",
"confirmations" : 263032,
"size" : 215,
"height" : 19999,
"version" : 1,
"merkleroot" : "c1b09fa6bdc0b12b15cc1400d598ffed29dd33b2e282093a48646d1b7b380c98",
"tx" : [
"c1b09fa6bdc0b12b15cc1400d598ffed29dd33b2e282093a48646d1b7b380c98"
],
"time" : 1248291140,
"nonce" : 1085206531,
"bits" : "1d00ffff",
"difficulty" : 1.00000000,
"chainwork" : "00000000000000000000000000000000000000000000000000004e204e204e20",
"previousblockhash" : "000000006eb5c2799b0f5fafab6435daeecef8e7f609b731c9879c3f74f28c73",
"nextblockhash" : "00000000770ebe897270ca5f6d539d8afb4ea4f4e757761a34ca82e17207d886"
}
3. 根據tx查詢單筆交易的資訊：
沒建index時，只能查詢自己錢包的資訊，若不是錢包的交易，則返回如下：
./bitcoin-cli getrawtransaction c1b09fa6bdc0b12b15cc1400d598ffed29dd33b2e282093a48646d1b7b380c98
error: {"code":-5,"message":"Invalid or non-wallet transaction id"}
那怎麼辦呢? 直接分析程式碼找原因：
// Return transaction in tx, and if it was found inside a block, its hash is placed in hashBlock
bool GetTransaction(const uint256 &hash, CTransaction &txOut, uint256 &hashBlock, bool fAllowSlow)
{
CBlockIndex *pindexSlow = NULL;
{
LOCK(cs_main);
{
if (mempool.lookup(hash, txOut))
{
return true;
}
}
if (fTxIndex) {
CDiskTxPos postx;
if (pblocktree->ReadTxIndex(hash, postx)) {
CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
CBlockHeader header;
try {
file >> header;
fseek(file, postx.nTxOffset, SEEK_CUR);
file >> txOut;
} catch (std::exception &e) {
return error("%s : Deserialize or I/O error - %s", __func__, e.what());
}
hashBlock = header.GetHash();
if (txOut.GetHash() != hash)
return error("%s : txid mismatch", __func__);
return true;
}
}
if (fAllowSlow) { // use coin database to locate block that contains transaction, and scan it
int nHeight = -1;
{
CCoinsViewCache &view = *pcoinsTip;
CCoins coins;
if (view.GetCoins(hash, coins))
nHeight = coins.nHeight;
}
if (nHeight > 0)
pindexSlow = chainActive[nHeight];
}
}
if (pindexSlow) {
CBlock block;
if (ReadBlockFromDisk(block, pindexSlow)) {
BOOST_FOREACH(const CTransaction &tx, block.vtx) {
if (tx.GetHash() == hash) {
txOut = tx;
hashBlock = pindexSlow->GetBlockHash();
return true;
}
}
}
}
return false;
}
我們可以看出若fTxIndex為true，則可以直接搜尋index獲取block資訊
通過-reindex -txindex建立索引，呼叫：
./bitcoind -reindex -txindex
這個過程在我的mac上跑了數個小時。。。。。。
-txindex Maintain a full transaction index (default: 0)
-reindex Rebuild block chain index from current blk000??.dat files
再次查詢
./bitcoin-cli getrawtransaction c1b09fa6bdc0b12b15cc1400d598ffed29dd33b2e282093a48646d1b7b380c98
01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff0704ffff001d0168ffffffff0100f2052a01000000434104cab13751ae7f0e0e49f8fb345e931bc6a6349502da0cbcad98e9d95110ebde5ca7af9eb09639c022ac251b44d0fa200b54011198a405984a8ff92ea9028d6d60ac00000000
解碼交易資料
./bitcoin-cli decoderawtransaction 01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff0704ffff001d0168ffffffff0100f2052a01000000434104cab13751ae7f0e0e49f8fb345e931bc6a6349502da0cbcad98e9d95110ebde5ca7af9eb09639c022ac251b44d0fa200b54011198a405984a8ff92ea9028d6d60ac00000000
{
"txid" : "c1b09fa6bdc0b12b15cc1400d598ffed29dd33b2e282093a48646d1b7b380c98",
"version" : 1,
"locktime" : 0,
"vin" : [
{
"coinbase" : "04ffff001d0168",
"sequence" : 4294967295
}
],
"vout" : [
{
"value" : 50.00000000,
"n" : 0,
"scriptPubKey" : {
"asm" : "04cab13751ae7f0e0e49f8fb345e931bc6a6349502da0cbcad98e9d95110ebde5ca7af9eb09639c022ac251b44d0fa200b54011198a405984a8ff92ea9028d6d60 OP_CHECKSIG",
"hex" : "4104cab13751ae7f0e0e49f8fb345e931bc6a6349502da0cbcad98e9d95110ebde5ca7af9eb09639c022ac251b44d0fa200b54011198a405984a8ff92ea9028d6d60ac",
"reqSigs" : 1,
"type" : "pubkey",
"addresses" : [
"1KWj3Jk8xvS6fDdhQBsfmerscSGsS6CMiS"
}
}
}
以上過程基本滿足了大部分的查詢需求：輸入交易ID、區塊高度或雜湊值（BTC）
至於通過"地址"查詢，需要通過蒐集這個地址對應的交易輸入輸出存入資料庫
部分程式碼如下：
function updateKeys($hash160,$pubkey,$blockhash)
{
global $db;
$address=hash160ToAddress($hash160);
$result=pg_fetch_assoc(pg_query_params($db,"SELECT pubkey,encode(hash160,'hex') AS hash160 FROM keys WHERE hash160=decode($1,'hex')",array($hash160)));
if(!$result && !is_null($pubkey))
{
pg_query_params($db, "INSERT INTO keys VALUES (decode($1,'hex'),$2,decode($3,'hex'),decode($4,'hex'));",array($hash160,$address,$pubkey,$blockhash));
}
else if(!$result)
{
pg_query_params($db, "INSERT INTO keys(hash160,address,firstseen) VALUES (decode($1,'hex'),$2,decode($3,'hex'));",array($hash160,$address,$blockhash));
}
else if($result && !is_null($pubkey) && is_null($result["pubkey"]))
{
if($result["hash160"]!=strtolower(hash160($pubkey)))
{
sleep(10);
die("Hashes don't match");
}
pg_query_params($db, "UPDATE keys SET pubkey = decode($1,'hex') WHERE hash160=decode($2,'hex');",array($pubkey,$hash160));
}
}
案例分析：如何獲取一筆交易的輸入地址？（此case可用在獲取打款地址上）
如何根據txid獲取打款地址呢？其實可以基於blockchain的鏈式結構逆向推導
首先 gettransaction txid
[vin] => Array
(
[0] => Array
(
[txid] => 63876d10a13f3810a1d568c6ac7154f9b8a590cfc91cf8a17756fb099addf2b5
[vout] => 1
獲取到此次的tx得資訊詳細，根據vin裡的txid逆向查詢， txid二次查詢，gettransaction vin->txid
然後根據vout索引得到輸入address
[vout] => Array
(
[0] => Array
(
[value] => 0.16928006
[n] => 0
[scriptPubKey] => Array
(
[asm] => OP_DUP OP_HASH160 1715447427ac1cdfb7c5ba359154c37c5e9caa2b OP_EQUALVERIFY OP_CHECKSIG
[hex] => 76a9141715447427ac1cdfb7c5ba359154c37c5e9caa2b88ac
[reqSigs] => 1
[type] => pubkeyhash
[addresses] => Array
(
[0] => LML1HJvP8jfeiwgSVmYfNGsedYfDrzKmq3
)
)