PRB: CGI Application Hangs When Reading Data Posted from Browser

• Microsoft Internet Explorer (Programming) version 4.0

SYMPTOMS

When data is posted from the Internet Explorer to a CGI application, the browser will display an hourglass. At some point, the browser will time out and display an error message indicating that it has done so.

CAUSE

The behavior of the Internet Explorer was changed with Internet Explorer 4.0 to more closely reflect the HTTP specification (RFC 2068). This comment is taken from RFC 2068.

NOTE: Certain buggy HTTP/1.0 client implementations generate an extra CRLFs after a POST request. To restate what is explicitly forbidden by the BNF, an HTTP/1.1 client must not preface or follow a request with an extra CRLF.

CGI applications that rely on the CRLF will not work correctly with Internet Explorer 4.0. The following code is an example that will fail:

      if (!gets(cgiinput)) {
      printf("Couldn't read CGI input from STDIN.\n") ;
      exit(1) ;
   } 

RESOLUTION

A well-behaved CGI application will read exactly the number of bytes specified by the browser in the content-length header. The following code behaves correctly:

   if ( !(content_length = atoi(getenv("CONTENT_LENGTH"))) ) {
      printf("No Content-Length was sent with the POST request.\n") ;
      exit(1) ;
   }

   if (!fread(cgiinput, content_length, 1, stdin)) {
      printf("Couldn't read CGI input from STDIN.\n") ;
      exit(1) ;
   } 

STATUS

© Microsoft Corporation 1998, All Rights Reserved.
Contributions by Robert E Duke, Microsoft Corporation

Additional query words:

Keywords : iisscript
Version : WINDOWS:4.0
Platform : WINDOWS
Issue type : kbprb