[2005] Socket Host Not Found ?

[killer7k]

Hi ,

i'am running an application that grab world news from some news website
some of them work & some not it say Unknown Host
here you my code some mod from MSDN one :

 Private Shared Function ConnectSocket(ByVal server As String, ByVal port As Integer) As Socket
        Dim s As Socket = Nothing
        Dim hostEntry As IPHostEntry = Nothing

        ' Get host related information.
''''''''''''''''''
'Here the problem , the exception..
is there anyway without convert the host to ip ? 
        hostEntry = Dns.GetHostEntry(server)

        ' Loop through the AddressList to obtain the supported AddressFamily. This is to avoid
        ' an exception that occurs when the host host IP Address is not compatible with the address family
        ' (typical in the IPv6 case).
        Dim address As IPAddress

        For Each address In hostEntry.AddressList
            Dim endPoint As New IPEndPoint(address, port)
            Dim tempSocket As New Socket(endPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp)

            tempSocket.Connect(endPoint)

            If tempSocket.Connected Then
                s = tempSocket
                Exit For
            End If

        Next address

        Return s
    End Function


    ' This method requests the home page content for the specified server.

    Private Shared Function SocketSendReceive(ByVal server As String, ByVal port As Integer) As String
        'Set up variables and String to write to the server.
        Dim ascii As Encoding = Encoding.ASCII
        Dim request As String = "GET / HTTP/1.1" + ControlChars.Cr + ControlChars.Lf + "Host: " + server + ControlChars.Cr + ControlChars.Lf + "Connection: Close" + ControlChars.Cr + ControlChars.Lf + ControlChars.Cr + ControlChars.Lf
        Dim bytesSent As [Byte]() = ascii.GetBytes(request)
        Dim bytesReceived(1255) As [Byte]

        ' Create a socket connection with the specified server and port.
        Dim s As Socket = ConnectSocket(server, port)

        If s Is Nothing Then
            Return "Connection failed"
        End If
        ' Send request to the server.
        s.Send(bytesSent, bytesSent.Length, 0)

        ' Receive the server  home page content.
        Dim bytes As Int32

        ' Read the first 256 bytes.
        'Dim page As [String] = "Default HTML page on " + server + ":" + ControlChars.Cr + ControlChars.Lf
        Dim page As [String] = ControlChars.Cr + ControlChars.Lf
        ' The following will block until the page is transmitted.
        Do
            bytes = s.Receive(bytesReceived, bytesReceived.Length, 0)
            page = page + Encoding.ASCII.GetString(bytesReceived, 0, bytes)
        Loop While bytes > 0

        Return page
    End Function


    Private Sub btnnavigate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btncheck.Click
        Dim host As String = "http://www.breakthrough.tv"
        Dim port As Integer = 80


        Dim result As String = SocketSendReceive(host, port)
        ListBox1.Items.Add(result)
'just showing on listbox to see if it work or not here


    End Sub

Thanks

[Atheist]

Why do you need to resolve the hostname separately? Why not just use the Connect overload that takes a hostname string argument?

Edit: By the way, what is the value of the endpoint when you get Unknown host?

[killer7k]

Why do you need to resolve the hostname separately? Why not just use the Connect overload that takes a hostname string argument?

Edit: By the way, what is the value of the endpoint when you get Unknown host?

yes Atheist i would like to connect to the website directly like with Webclient
but this only example i found on MSDN

[dbasnett]

i agree with atheist about just use overload.

it is not unusual for Dns.GetHostEntry(server) to fail. without actually seeing what is in server it is hard to tell why it failed. it should be in a try catch block though.

[killer7k]

i agree with atheist about just use overload.

do you have a simple example ?

[dbasnett]

aSocket.Connect("www.yahoo.com", 80)

[killer7k]

anyone ?

[Atheist]

What do you mean by "anyone"? dbasnett has given you the example you where asking for.

[killer7k]

What do you mean by "anyone"? dbasnett has given you the example you where asking for.

sorry to say but this line doesnt helped me at all

[Atheist]

Well then you'll have to express yourself better. You asked for a simple example on the use of the connect overload that took a hostname argument, and thats what dbasnett provided. If you need more help, just say so.

[killer7k]

Yes i'am new to Socket
i searched for some simple example on MSDN & is the one i posted ,but this one have to convert the host to ip ,i just need to connect directly with website name to read webpage source .dbasnett posted this line of code which doesnt helped me really .i just need simple example & after i can elaborate it

Thanks

[killer7k]

Atheist can you help me ?

[dbasnett]

        Dim IPhe As IPHostEntry
        Debug.WriteLine("") 
        Try 
            IPhe = System.Net.Dns.GetHostEntry("www.microsoft.com") 'lookup address
            Debug.WriteLine(IPhe.HostName) 
            Debug.WriteLine(IPhe.AddressList(0).ToString) 
        Catch ex As Exception 
            Debug.WriteLine("MS " & ex.Message) 
        End Try 
        Stop

[killer7k]

        Dim IPhe As IPHostEntry
        Debug.WriteLine("") 
        Try 
            IPhe = System.Net.Dns.GetHostEntry("www.microsoft.com") 'lookup address
            Debug.WriteLine(IPhe.HostName) 
            Debug.WriteLine(IPhe.AddressList(0).ToString) 
        Catch ex As Exception 
            Debug.WriteLine("MS " & ex.Message) 
        End Try 
        Stop

Hi dbasnett ,

Try this

 Dim IPhe As IPHostEntry

        Try
            IPhe = System.Net.Dns.GetHostEntry("http://www.gtcc.org/") 'lookup address
            ListBox1.Items.Add(IPhe.HostName)
            ListBox1.Items.Add(IPhe.AddressList(0).ToString)
        Catch ex As Exception
            MsgBox("MS " & ex.Message)
        End Try

i'am lost with Socket , i just need to a simple example how to read a webpage source code via Socket

can you help me ?

[dbasnett]

this "http://www.gtcc.org/" is not a FQDN. it is a web request TO an address

query this www.gtcc.org
and then add http://



in your original post you said

hostEntry = Dns.GetHostEntry(server)


if you had shown it like this

'server = http://www.gtcc.org/
hostEntry = Dns.GetHostEntry(server)

your problem would have been resolved.

we had no choice but to assume that you knew the difference between an address and a request.

[killer7k]

Thank you both for your help but i really really didnt get to work with Socket
That socket is really Hard & getting me insane

i'am just in need for simple code how get webpage source using Socket
is that so hard to be done ?

i check in the forum here , microsoft Forum , MSDN & others but no result
seem that socket very hard...

anyway Thank you for the help , i should stop searching how Socket work for now
hope next time i will be ready for it

[dbasnett]

if you are doing http why not use the WebBrowser control?

[killer7k]

if you are doing http why not use the WebBrowser control?

i need socket
have you ever tried to get webpage source via Socket ?

[dbasnett]

everything you wanted to know about http but were afraid to ask

http://www.faqs.org/rfcs/rfc2616.html

on the other hand

the DocumentText of the webbrowser control might be what you are looking for.