VB.NET套接字编程网络流错误 [英] VB.NET Socket Programming Network stream Error

问题描述

我正在做一个大学项目.该项目是网络银行系统.我设计了两个程序，一个用于服务器(管理员)，一个用于客户端(客户).通过TCP套接字进行连接.这是一个简短的说明:

当客户(客户)通过正确提供帐号和密码登录时，networkstream对象会正确传输帐号，但密码情况并非如此. 当我在服务器端提取密码时，它不是适合验证数据库中用户详细信息的Sql查询的有效字符串.密码字符串看起来像"abc，缺少双引号.缓冲区大小为10025.

这是服务器代码:

I am working on a college project . The project is network Banking system. I have designed two programs, one for server(admin) and one for the client(customers). The connection is via TCP sockets. here is a brief description:

When the customer(client) logs in by providing the account number and password correctly, the networkstream object transmits account number properly but this is not the case with passwords. When I extract the password on the server side it is not a valid string to fit into the Sql query for verifying the user details in the database. The password String looks like "abc with a missing closing double quotes. The buffer size is 10025.

Here is the server code:

Public Sub Client_Login()

       networkStream = clientSocket.GetStream()
       Dim bytes(10024) As Byte
       networkStream.Read(bytes, 0, CInt(clientSocket.ReceiveBufferSize))
       ClientID = (Encoding.ASCII.GetString(bytes))
       networkStream.Flush()

       
       networkStream.Read(bytes, 0, CInt(clientSocket.ReceiveBufferSize))
       ClientPassword = (Encoding.ASCII.GetString(bytes))
      networkStream.Flush()
       

       connection = New OleDbConnection("Provider=Microsoft.Jet.OleDb.4.0;data source= D:\Project(Pritam)\Networking Banking System\ActualDatabase.mdb")
       SQL = "Select * from ClientInfo  where Account_No= " & ClientID & "  and  [Password]='" & ClientPassword & "'"
       command = New OleDbCommand(SQL, connection)
       'Try
       connection.Open()
       reader = command.ExecuteReader()
       reader.Read()

       If reader.HasRows = True Then
           Dim ClientAccountNumber As Integer = reader("Account_No")  'extracts account number from database
           Dim PasswordClient As String = reader("Password")        ' extracts password from database

           If ClientAccountNumber = Val(ClientID) And PasswordClient = (ClientPassword) Then

               server_response = "Successful Login"
               Dim sendBytes As [Byte]() = Encoding.ASCII.GetBytes(server_response)
               networkStream.Write(sendBytes, 0, sendBytes.Length)
               networkStream.Flush()        

这是客户端代码:

Here is the client code:

Private Sub cmdSignin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSignin.Click

       If txtClientID.Text <> "" And txtClientPassword.Text <> "" Then

           Try

               networkStream = clientSocket.GetStream()
               Dim to_server As Byte() = Encoding.ASCII.GetBytes(txtClientID.Text)
               networkStream.Write(to_server, 0, to_server.Length)
               'networkStream.Flush()

               'Dim client_writer As New StreamWriter(clientSocket.GetStream())
               'client_writer.Write(txtClientPassword.Text)

               to_server = Encoding.ASCII.GetBytes(txtClientPassword.Text)
               networkStream.Write(to_server, 0, to_server.Length)
               networkStream.Flush()

               form_refresh()

               Dim login_Thread As Threading.Thread = New Threading.Thread(AddressOf login_final)
               login_Thread.Start()

           Catch ex As Exception
               MsgBox("Server not found" & vbCrLf & "Contact Administrator", MsgBoxStyle.Critical, "Notice!!")
               Me.Close()
           End Try
       Else

请帮助我，因为我很快就要提交我的项目.

预先感谢您

--EDIT kschuler:尝试修复代码块，对实际问题加粗以使其更引人注意.

Kindly help me as I''ve to submit my project very soon, please.

Thanking you in advance

--EDIT kschuler: tried to fix code blocks, bolded the actual question to make it stand out more.

推荐答案

这是由于缓冲区的大小是固定的.使它动态，它应该可以正常工作.

This is due to your buffer being a fixed size. Make it dynamic and it should work fine.

Dim bytes() As Byte
Redim bytes(CInt(clientSocket.ReceiveBufferSize)-1)
networkStream.Read(bytes, 0, CInt(clientSocket.ReceiveBufferSize))

公平地说，我很惊讶您的两组数据没有合并到单个网络数据包中.在VB6中曾经发生过这种情况，也许.NET处理的数据包略有不同

To be fair, I am quite surprised that your two sets of data didn''t get merged into a single network packet. That used to happen in VB6, maybe .NET handles packets slightly different

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