// 处理 Server 端可能发来的 Close
// return value:
// -1 error
// 0 不是Close
// 1 是Close，已经迫使ZChannel处于尚未初始化状态
// return InitialResult:
// 在 InitialResult::ResultInfo 中返回诊断信息
async Task <InitialResult> CheckServerCloseRequest()
{
if (this._channel.Connected == false || this._channel.DataAvailable == false)
{
return(new InitialResult()); // 没有发现问题
}
// 注意调用返回后如果发现出错，调主要主动 Close 和重新分配 TcpClient
RecvResult result = await ZChannel.SimpleRecvTcpPackage(this._channel._client, -1).ConfigureAwait(false);
if (result.Value == -1)
{
this.CloseConnection();
return(new InitialResult {
Value = -1, ErrorInfo = result.ErrorInfo
});
}
BerTree tree1 = new BerTree();
// TODO: 这里需要捕获异常，然后把 Package Dump 到日志文件(base64 形态)，便于事后分析调试
tree1.m_RootNode.BuildPartTree(result.Package,
0,
result.Package.Length,
out int nTotalLen);
if (tree1.GetAPDuRoot().m_uTag != BerTree.z3950_close)
{
// 不是Close
return(new InitialResult {
Value = 0
});
}
CLOSE_REQUEST closeStruct = new CLOSE_REQUEST();
int nRet = BerTree.GetInfo_closeRequest(
tree1.GetAPDuRoot(),
ref closeStruct,
out string strError);
if (nRet == -1)
{
this.CloseConnection();
return(new InitialResult {
Value = -1, ErrorInfo = strError
});
}
this.CloseConnection();
return(new InitialResult {
Value = 1, ResultInfo = closeStruct.m_strDiagnosticInformation
});
}
// 接收响应包
// 注意调用返回后如果发现出错，调主要主动 Close 和重新分配 TcpClient
// parameters:
// nMaxLength 读入等待处理的 bytes 极限数字。超过了这个，还没有找到结束符，就会抛出异常。意在防范攻击。-1 表示不限制
// touch_func 回调函数，用于保持通道活跃
public static async Task <RecvResult> SimpleRecvTcpPackage(TcpClient _client,
int nMaxLength,
delegate_touch touch_func = null)
{
return(await ZChannel.SimpleRecvTcpPackage(_client,
null,
(package, start, length) =>
{
bool bRet = BerNode.IsCompleteBER(package,
start,
length,
out long remainder);
if (bRet == true)
{
return new Tuple <int, byte>((int)remainder, 0);
}
return new Tuple <int, byte>(0, 0);
},
touch_func,
nMaxLength).ConfigureAwait(false));
}
public async Task <InitialResult> HugeRequestAttack(TargetInfo targetinfo,
int length)
{
bool bTry = true;
{
// 处理通讯缓冲区中可能残留的 Close Response
// return value:
// -1 error
// 0 不是Close
// 1 是Close，已经迫使ZChannel处于尚未初始化状态
InitialResult result = await CheckServerCloseRequest().ConfigureAwait(false);
}
if (bTry == false ||
this._channel.Connected == false ||
this._channel.Initialized == false ||
this._channel.HostName != targetinfo.HostName ||
this._channel.Port != targetinfo.Port)
{
if (this._channel.Connected == false)
{
Result result = await this._channel.Connect(targetinfo.HostName, targetinfo.Port).ConfigureAwait(false);
if (result.Value == -1)
{
return new InitialResult {
Value = -1, ErrorInfo = result.ErrorInfo
}
}
;
}
// this.Stop.SetMessage("正在执行Z39.50初始化 ...");
// 2018/7/4
if (bTry == false)
{
this._channel.Initialized = false;
}
{
// return Value:
// -1 出错
// 0 成功
Result result = await ZChannel.SendInfinitPackage(
this._channel._client,
length).ConfigureAwait(false);
if (result.Value == -1)
{
return(new InitialResult(result));
}
return(new InitialResult(result));
}
}
return(new InitialResult {
Value = 1
});
}
}
