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Re: SPNEGO bug in CFNetwork

We really need a fix for this problem!  The problem is pretty clear, the CFNetwork layer is assuming that the scheme (e.g. ftp, http, https) can be mapped directly into a service principal.  This works for ftp, but not for http (they test for and drop the 's').  Here is a patch:

--- CFHTTPAuthentication.c      2005-09-30 21:09:05.118012864 -0700
+++ CFHTTPAuthentication.c.fixed        2005-09-30 21:11:30.516734591 -0700
@@ -2052,16 +2052,19 @@
                        UInt8* hostname = _CFStringGetOrCreateCString(alloc, host, buf1, &len, kCFStringEncodingASCII);
                        UInt8* servicetype;

                        len = sizeof(buf2);
                        servicetype = _CFStringGetOrCreateCString(alloc, scheme, buf2, &len, kCFStringEncodingASCII);

                        if (!strcmp(servicetype, "https"))
                                servicetype[4] = '\0';
+
+                       if (!strcmp(servicetype, "http"))
+                               strcpy(servicetype, "HTTP");

                        if (!GetSvcTicketForHost(hostname, servicetype, &tktLen, &ticket)) {
                                result->_preferred = current_scheme;
                        }

                        if (hostname != buf1)
                                CFAllocatorDeallocate(alloc, hostname);


All this does is check for "http" and maps it to "HTTP" before calling GetSvcTicketForHost.  I believe that this will fix the problem and not have any deleterious impact.

-- scooter

Becky Willrich wrote:
I looked at the bug - looks like the spec sez that string should be case-insensitive. Where precisely is this failing? That is, what server is requiring precisely the uppercase string?
Becky -

Kerberos 5 principal names are normally case sensitive. Just about every other server principal uses a lower case service name; SPNEGO is the odd one out. In fact the earliest versions of the SPNEGO drafts did specify http/<hostname>; however this was broken in later drafts, and in deployed code.

Simple explanation of the normal convention in the java docs here: http://java.sun.com/j2se/1.5.0/docs/guide/security/jgss/tutorials/KerberosReq.html

SPNEGO 'spec' : <<
[....]

  1. Create the SPNs associated with this account on the KDC:

     setspn—A host/mysrvr.proseware.com mysrvr
     setspn—A HTTP/mysrvr.proseware.com mysrvr

         *Note* Use upper-case "HTTP" to match the way Internet
         Explorer builds SPNs. Alternatively, you can run ktpass (as
         shown below) to create the SPNs. When using the "*-princ*"
         option of ktpass, you are specifying the Kerberos
>>

Kitten hasn't changed this, because it would break the installed base. 
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