BUG: Set-Cookie Is Ignored in CGI When Combined With Location (176113)

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http://www.microsoft.com/technet/security/prodtech/IIS.mspx

RESOLUTION

This behavior is in violation of the CGI specification, which states, "Any headers that are not server directives are sent directly back to the client. Currently, this specification defines three server directives..."

As a workaround, make sure the file name of the EXE begins with "nph-" and manually create all HTTP headers in your program. "nph-" indicates to the server that the CGI program is to be run in non-parsed headers mode. CGI has two modes. In normal mode (parsed headers), you must send one of the CGI directives to standard output (Content-type, Location, or Status). CGI formats a valid HTTP response line based on the directive you sent. It formats other standard HTTP headers for you, and it should include any other headers that you have specified.

The other mode is non-parsed header mode. In this mode CGI does not set any headers itself. The CGI program must format a full HTTP response including the response line and all headers. The server will not add or modify any headers for you in this mode.

The convention is that a CGI program whose name begins with "nph-" is run in non-parsed header mode; otherwise, CGI programs are run in parsed header mode.

MORE INFORMATION

Steps to Reproduce Behavior

Compile this CGI program as a Win32 Console Application and place it in a folder on your IIS server where it can be executed:

#include <stdio.h>
int main()
{
  printf("Location: %s\r\n", "http://www.yahoo.com");
  printf("Set-Cookie: Name1=Value1; path=/;
    expires=Fri, 22 May 1998 21:00:00 GMT\r\n\r\n");
  return 0;
}

Call the CGI program from your browser and observe its output (via Network Monitor, for example). It will be similar to this:

HTTP/1.0 302 Object moved
Location: http://www.yahoo.com
Server: Microsoft-IIS/2.0
Content-Type: text/html
Content-Length: 145

<head><title>Document moved</title></head>
<body><h1>Object Moved</h1>This document may be found
<a HREF="http://www.yahoo.com">here</a></body>

Note that the Set-Cookie header has not been sent by IIS. If you have cookie warnings turned on in your browser, no warning appears.

To allow a cookie to be set in a 302 response, use code similar to the following, and prefix "nph-" to the name of the executable file:

#include <stdio.h>
int main()
{
  printf("HTTP/1.0 302 Redirect\r\n");
  printf("Location: %s\r\n", "http://www.yahoo.com");
  printf("Set-Cookie: Name=Value; path=/; expires=Fri, 22 May 1998 21:00:00
   GMT\r\n\r\n");
  return 0;
}

The output is similar to the following. Note that the cookie is now sent, and no headers are added by the server.

HTTP/1.0 302 Redirect
Location: http://www.yahoo.com
Set-Cookie: Name=Value; path=/; expires=Fri, 22 May 1998 21:00:00 GMT

BUG: Set-Cookie Is Ignored in CGI When Combined With Location (176113)

SYMPTOMS

RESOLUTION

STATUS

MORE INFORMATION

Steps to Reproduce Behavior

REFERENCES