Question

我正在尝试重定向我的流程（用VB.NET编写）的standard和error的输出，其中我正在执行连续命令。这是一个tshark命令（Wireshark的命令行工具），可在运行时捕获网络流量。我尝试了以下两个命令：

-i 5 -B 1 -w /sample.pcap --print -Tfields -e frame.number -e ip.addr -e tcp -e _ws.col.Info -E separator=/t
-i 10 -T fields -e dns.qry.name src port 53

这两个命令在命令提示符下都很好用。但是，当尝试重定向代码中的输出时，执行StreamReader.ReadLine时，只有命令号1起作用，而第二个命令卡住。

请注意，我知道ReadLine等待流读取新行，以上两个命令都会为每个捕获的数据包生成新的输出行。我确实也尝试过使用Read和ReadBlock（关于代码中需要的更改），但是第二个命令都不起作用。

这是我的代码：

Public Class Form1

    Dim output As String
    Dim oProcess As New Process()



    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
            Try
                Dim oStartInfo As New ProcessStartInfo("C:\Program Files\Wireshark\tshark.exe", "-i 10 -T fields -e dns.qry.name src port 53")
                oStartInfo.UseShellExecute = False
                oStartInfo.RedirectStandardOutput = True
                oStartInfo.RedirectStandardError = True
                oStartInfo.CreateNoWindow = True
                oStartInfo.WindowStyle = ProcessWindowStyle.Hidden
                oProcess.StartInfo = oStartInfo
            Catch ex As Exception
                MsgBox(ex)
            End Try
            BackgroundWorker1.RunWorkerAsync()
            Button1.Enabled = False
            Button2.Enabled = True
        End Sub

        Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
            Try
                Threading.Thread.Sleep(2000)
                If oProcess.Start() Then
                    Dim sOutput As String
                    Using oStreamReader As System.IO.StreamReader = oProcess.StandardOutput
                        sOutput = oStreamReader.ReadLine
                        While Not sOutput Is Nothing
                            output = sOutput & vbNewLine
                            BackgroundWorker1.ReportProgress(10)
                            sOutput = sOutput + vbNewLine + oStreamReader.ReadLine
                        End While
                    End Using

                    Using oStreamReader As System.IO.StreamReader = oProcess.StandardError
                        sOutput = oStreamReader.ReadLine
                        While Not sOutput Is Nothing
                            output = sOutput & vbNewLine
                            BackgroundWorker1.ReportProgress(10)
                            sOutput = sOutput + vbNewLine + oStreamReader.ReadLine
                        End While
                    End Using
                Else
                    MsgBox("Error starting the process")
                End If
            Catch ex As Exception
                MsgBox(ex)
            End Try

        End Sub

        Private Sub BackgroundWorker1_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
            TextBox1.Text = output
            TextBox1.Select(0, 0)
        End Sub

        Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
            BackgroundWorker1.CancelAsync()
            Button1.Enabled = True
            Button2.Enabled = False
        End Sub

        Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        End Sub
    End Class

Answer 1

这全是一个tshark问题，从没有一个VB.Net问题。正如Mr.Kurt Knochner在回答问题How to pipe tshark output in realtime?时提到的：

tshark输出已缓冲。如果需要，请使用tshark选项-l tshark在每个数据包之后刷新STDOUT。

并参考tshark here的文档：

-l在打印每个数据包的信息后刷新标准输出。

因此，为了使其正常运行，我在命令行中添加了--print选项和-l，现在它就像一个超级按钮一样工作，现在看起来像这样：

tshark --print -l -i 10 -w ./sample.pcap -E separator=/t -T fields -e frame.number -e dns.qry.name src port 53

这是我的最终代码版本：

Public Class Form1

    Dim outputQueue As New Queue(Of String)
    Dim captureAdapterID As Integer = 0
    Dim oProcess As Process

    Private Sub Button1_Click(sender1 As Object, e1 As EventArgs) Handles Button1.Click
        Button1.Enabled = False
        Button2.Enabled = True
        captureAdapterID = (ComboBox1.SelectedIndex + 1)
        BackgroundWorker1.RunWorkerAsync()
    End Sub

    Private Sub BackgroundWorker1_DoWork(sender1 As Object, e1 As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
        Try
            oProcess = New Process()
            Dim oStartInfo As New ProcessStartInfo("C:\Program Files\Wireshark\tshark.exe", " --print -l -i " & captureAdapterID & " -w ./sample.pcap -E separator=/t -T fields -e frame.number -e dns.qry.name src port 53")
            oStartInfo.WorkingDirectory = New Uri(System.Windows.Forms.Application.StartupPath).LocalPath
            oStartInfo.UseShellExecute = False
            oStartInfo.RedirectStandardOutput = True

            oStartInfo.RedirectStandardError = True
            oStartInfo.CreateNoWindow = True
            oStartInfo.WindowStyle = ProcessWindowStyle.Hidden
            oProcess.StartInfo = oStartInfo

            If oProcess.Start() Then
                appendOutput("Capturing on device: " & captureAdapterID & " started.")
                Dim sOutput As String
                Using oStreamReader As System.IO.StreamReader = oProcess.StandardOutput
                    sOutput = oStreamReader.ReadLine
                    While Not sOutput Is Nothing
                        appendOutput(sOutput)
                        sOutput = oStreamReader.ReadLine
                    End While
                End Using

                Using oStreamReader As System.IO.StreamReader = oProcess.StandardError
                    sOutput = oStreamReader.ReadLine
                    While Not sOutput Is Nothing
                        appendOutput(sOutput)
                        sOutput = oStreamReader.ReadLine
                    End While
                End Using

                MsgBox("finished")
            Else
                MsgBox("Error starting the process")
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        Finally
            BackgroundWorker1.ReportProgress(10)
        End Try

    End Sub

    Private Sub appendOutput(sOutput As String)
        outputQueue.Enqueue(sOutput)
        BackgroundWorker1.ReportProgress(10)
    End Sub

    Private Sub BackgroundWorker1_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
        Dim i As Integer = 0
        For i = 0 To outputQueue.Count - 1 Step 1
            RichTextBox1.AppendText(outputQueue.Dequeue & vbNewLine)
        Next
        RichTextBox1.ScrollToCaret()
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        BackgroundWorker1.CancelAsync()
        oProcess.Kill()
        Button1.Enabled = True
        Button2.Enabled = False
    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Try
            Dim process As New Process()
            Dim oStartInfo As New ProcessStartInfo("C:\Program Files\Wireshark\tshark.exe", " -D")
            oStartInfo.WorkingDirectory = New Uri(System.Windows.Forms.Application.StartupPath).LocalPath
            oStartInfo.UseShellExecute = False
            oStartInfo.RedirectStandardOutput = True

            oStartInfo.RedirectStandardError = True
            oStartInfo.CreateNoWindow = True
            oStartInfo.WindowStyle = ProcessWindowStyle.Hidden
            process.StartInfo = oStartInfo

            If process.Start() Then

                Dim sOutput As String
                Using oStreamReader As System.IO.StreamReader = process.StandardOutput
                    sOutput = oStreamReader.ReadToEnd
                    If Not sOutput Is Nothing Then
                        ComboBox1.Items.AddRange(sOutput.Trim.Split(vbNewLine))
                        Try
                            ComboBox1.SelectedIndex = 0
                        Catch ex As Exception

                        End Try
                    End If
                End Using
            Else
                MsgBox("Error starting the get adapter process failed")
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub
End Class

VB.NET重定向停留在StreamReader.ReadLine

1 个答案: