修复开源项目 btcd RPC 实现比特币获取区块的问题

btcd 提供的 RPC 接口中，获取区块和交易详情接口 GetBlockVerboseTx 存在一个 BUG, 具体可以查看 issue :

[RPC] getblock command has been changed

getblock 接口详情如下

getblock "blockhash" ( verbosity )
If verbosity is 0, returns a string that is serialized, hex-encoded data for block 'hash'.
If verbosity is 1, returns an Object with information about block <hash>.
If verbosity is 2, returns an Object with information about block <hash> and information about each transaction.
Arguments:
1. "blockhash"          (string, required) The block hash
2. verbosity              (numeric, optional, default=1) 0 for hex encoded data, 1 for a json object, and 2 for json object with transaction data

我没有在 btcd 提 pull request, 故把修改过的文件提交到这个 repo, 使用 btcd 时直接覆盖对应文件即可。

Command: getblock

修改的代码

在 btcd 中，获取区块和区块中所有交易详情的 RPC 方法是：

func (c *Client) GetBlockVerboseTx(blockHash *chainhash.Hash) (*btcjson.GetBlockVerboseResult, error) {
  return c.GetBlockVerboseTxAsync(blockHash).Receive()
}

接着我们再看看 GetBlockVerboseTxAsync 方法：

func (c *Client) GetBlockVerboseTxAsync(blockHash *chainhash.Hash) FutureGetBlockVerboseResult {
  hash := ""
  if blockHash != nil {
      hash = blockHash.String()
  }

  cmd := btcjson.NewGetBlockCmd(hash, btcjson.Bool(true), btcjson.Bool(true))
  return c.sendCmd(cmd)
}

其中 NewGetBlockCmd 函数接受三个参数，后面两个为布尔类型，显然是不对的，getblock 接口格式为 getblock "blockhash" ( verbosity )

因为我只是做了小修改再加上对 btcd 源码不怎么熟悉，为了不引入新的 bug ，我在这里只添加代码，不删除，不修改 ...

func (c *Client) GetBlockVerboseTxM(blockHash *chainhash.Hash) (*btcjson.GetBlockVerboseResult, error) {
  return c.GetBlockVerboseTxAsyncM(blockHash).Receive()
}

...

func (c *Client) GetBlockVerboseTxAsyncM(blockHash *chainhash.Hash) FutureGetBlockVerboseResult {
  hash := ""
  if blockHash != nil {
      hash = blockHash.String()
  }

  cmd := btcjson.NewGetBlockCmdM(hash, 2)
  return c.sendCmd(cmd)
}

在 rpcclient/chain.go 修改，不删除原来的方法，追加修改的两个方法。接下来继续看看 NewGetBlockCmdM 方法，在 btcjson/chainsvrcmds.go 文件中：

func NewGetBlockCmdM(hash string, verbose int) *GetBlockCmdM {
  return &GetBlockCmdM{
      Hash:    hash,
      Verbose: &verbose,
  }
}

...
// GetBlockCmdM defines the getblock JSON-RPC command.
type GetBlockCmdM struct {
  Hash    string
  Verbose *int `jsonrpcdefault:"1"`
}
...

，通过 getblock "blockhash" 2 在比特币节点的返回数据中，Unmarshal 后的结构体 GetBlockVerboseResult Tx 字段类型应该改为 TxRawResult，在 btcjson/chainsvrresults.go 文件中:

...
type GetBlockVerboseResult struct {
    Hash          string        `json:"hash"`
    Confirmations uint64        `json:"confirmations"`
    StrippedSize  int32         `json:"strippedsize"`
    Size          int32         `json:"size"`
    Weight        int32         `json:"weight"`
    Height        int64         `json:"height"`
    Version       int32         `json:"version"`
    VersionHex    string        `json:"versionHex"`
    MerkleRoot    string        `json:"merkleroot"`
    Tx            []TxRawResult `json:"tx,omitempty"`
    RawTx         []TxRawResult `json:"rawtx,omitempty"`
    Time          int64         `json:"time"`
    Nonce         uint32        `json:"nonce"`
    Bits          string        `json:"bits"`
    Difficulty    float64       `json:"difficulty"`
    PreviousHash  string        `json:"previousblockhash"`
    NextHash      string        `json:"nextblockhash,omitempty"`
}

最后，在 btcjson/chainsvrcmds.go 文件中修改 getblock 命令和修改后的方法绑定:

MustRegisterCmd("getblock", (*GetBlockCmdM)(nil), flags)

fix verbocity in getblock command for btcd

When i call getblock by btcd rpcclient, the generated rpc command looks like this:

{
"jsonrpc":"1.0",
"method":"getblock",
"params":
  ["0000000000000000015ed7a2934f8ecb39eda15459376fff64284e1a87688d5d",true,true],
"id":1
}

the right generation sendCmd should look like this:

{
  "jsonrpc":"1.0",
  "method":"getblock",
  "params":["0000000000000000015ed7a2934f8ecb39eda15459376fff64284e1a87688d5d",2],
  "id":1
}

Original "getblock" command accept 2 arguments:

blockhash
verbosity (numeric, optional, default=1) 0 for hex encoded data, 1 for a json object, and 2 for json object with transaction data

getblock "blockhash" ( verbosity )
If verbosity is 0, returns a string that is serialized, hex-encoded data for block 'hash'.
If verbosity is 1, returns an Object with information about block <hash>.
If verbosity is 2, returns an Object with information about block <hash> and information about each transaction.
Arguments:
1. "blockhash"          (string, required) The block hash
2. verbosity              (numeric, optional, default=1) 0 for hex encoded data, 1 for a json object, and 2 for json object with transaction data