Web Exception !

[AliAmjad]

I'm getting an unusual error message may be I'm wrong here is the error can anyone please tell me how to resolve it: The server committed a protocol violation. Section=ResponseHeader Detail=CR must be followed by LF And here is the code that raised this error:

    Dim wr As HttpWebRequest
    Dim wrs As HttpWebResponse

    wr = HttpWebRequest.Create("http://www.google.com/")
    wr.Method = "HEAD"
    wrs = wr.GetResponse()
    MsgBox(wrs.Headers.ToString())

AliAmjad(MCP) First make it Run THEN make it Run Fast!

[Dave Kreskowiak]

According to the error message, your code didn't generate the error, Google's web server did. HttpWebRequest is correct is saying so because it's following the parsing rules for HTTP 1.1 headers closer to the RFC specification than Google web server did putting the headers together. It's not Google's fault really, but the people who wrote the web server. There's an old recommendation in the RTF for HTTP 1.0 that said something like: "the line terminator for message-header fields is the sequence CRLF. However, we recommend that applications, when parsing such headers, recognize a single LF as a line terminator and ignore the leading CR." The headers comming back from the server ARE, according to which section of the RFC for HTTP you're reading, malformed. You can turn on an option in your applications app.config file to force HttpWebRequest to relax it's parsing rules and suddenly start working with a large collection of web servers that were never "fixed" because "they worked before!"

<configuration>
<system.net>
<settings>
<httpWebRequest useUnsafeHeaderParsing="true" />
</settings>
</system.net>
</configuration>

A guide to posting questions on CodeProject[^]
Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
     2006, 2007

[AliAmjad]

I've done some research before posting this question on Code Project and found the same solution in Msdn forum and did the same thing but it didn't display the headers received from the server but now it did I think there was something wrong with my network connection. As far as solution goes don't you think that Microsoft should make this class more fault tolerant so that it can handle such situations.

AliAmjad(MCP) First make it Run THEN make it Run Fast!

[Dave Kreskowiak]

AliAmjad wrote:

As far as solution goes don't you think that Microsoft should make this class more fault tolerant so that it can handle such situations.

They did!! As I've already said, you have to turn this option on in order to use the non-RFC compliant parser. In this particular case, the guy who the HttpWebRequest class wasn't as lazy as the guy who wrote the web server that Google, and tons of other sites, are using.

A guide to posting questions on CodeProject[^]
Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic
     2006, 2007