emacs-22.2: regression, cannot compile with heimdal but can with mit-krb5

emacs-22.2: regression, cannot compile with heimdal but can with mit-krb5

[Martin MOKREJŠ]

Hi,
  it seems there is an new incompatibility introduced in 22.2.
I would like to point you to the bug report at 
http://bugs.gentoo.org/show_bug.cgi?id=215558


Briefly (credits to Michael Hammer (mueli)):

Here is the definition of the krb5_error struct in mit-krb5 which seams
compatible with emacs-22.2:

typedef struct _krb5_error {
    krb5_magic magic;
    /* some of these may be meaningless in certain contexts */
    krb5_timestamp ctime;               /* client sec portion; optional */
    krb5_int32 cusec;                   /* client usec portion; optional */
    krb5_int32 susec;                   /* server usec portion */
    krb5_timestamp stime;               /* server sec portion */
    krb5_ui_4 error;                    /* error code (protocol error #'s) */
    krb5_principal client;              /* client's principal identifier;
                                           optional */
    krb5_principal server;              /* server's principal identifier */
    krb5_data text;                     /* descriptive text */
    krb5_data e_data;                   /* additional error-describing data */
} krb5_error;

and here is the heimdal code. You can see that the struct members are named
differently: 

typedef struct KRB_ERROR {
  krb5int32 pvno;
  MESSAGE_TYPE msg_type;
  KerberosTime *ctime;
  krb5int32 *cusec;
  KerberosTime stime;
  krb5int32 susec;
  krb5int32 error_code;
  Realm *crealm;
  PrincipalName *cname;
  Realm realm;
  PrincipalName sname;
  heim_general_string *e_text;
  heim_octet_string *e_data;
} KRB_ERROR;


You can see the difference:

krb5_data text; <-> heim_general_string *e_text;
---
text <-> e_text

Is it possible to patch pop.c that it supports both versions? I would say
that's an issue for emacs upstream - isn't it?


One more comment on this topic. I've just looked into rfc4120 (2005) (didn't
change from RFC1510 (1993) which is referred to in
http://web.mit.edu/Kerberos/papers.html#k5-protocol) and found that heimdal is
here the standard conform implementation:

   KRB-ERROR       ::= [APPLICATION 30] SEQUENCE {
           pvno            [0] INTEGER (5),
           msg-type        [1] INTEGER (30),
           ctime           [2] KerberosTime OPTIONAL,
           cusec           [3] Microseconds OPTIONAL,
           stime           [4] KerberosTime,
           susec           [5] Microseconds,
           error-code      [6] Int32,
           crealm          [7] Realm OPTIONAL,
           cname           [8] PrincipalName OPTIONAL,
           realm           [9] Realm -- service realm --,
           sname           [10] PrincipalName -- service name --,
           e-text          [11] KerberosString OPTIONAL,
           e-data          [12] OCTET STRING OPTIONAL
   }




Please if possible, post an answer&fix to the bugzilla at gentoo.org as well.
Thanks,
martin

Re: emacs-22.2: regression, cannot compile with heimdal but can with mit-krb5

[Ulrich Mueller]

[-- Attachment #1: Type: text/plain, Size: 1260 bytes --]

>>>>> On Tue, 01 Apr 2008, Martin MOKREJŠ wrote:

> I would like to point you to the bug report at
> http://bugs.gentoo.org/show_bug.cgi?id=215558

> Briefly (credits to Michael Hammer (mueli)):

> Here is the definition of the krb5_error struct in mit-krb5 which
> seams compatible with emacs-22.2:
> [...]
>    krb5_data text;                     /* descriptive text */
>    krb5_data e_data;                   /* additional error-describing data */
> [...]

> and here is the heimdal code. You can see that the struct members
> are named differently: 
> [...]
>  heim_general_string *e_text;
>  heim_octet_string *e_data;
> [...]

Hi,

Two alternative ways have been suggested (see Gentoo bug mentioned
above) to make Emacs compile also with Heimdal:

   1. Honza Macháček has pointed out that there exists the
      following patch from T2, which uses "e_data" instead of "text":
      <http://svn.exactcode.de/t2/branches/7.0/package/security/heimdal/emacs-pop.diff>

   2. The patch (by myself) attached to this message, which adds an
      autoconf test, in order to determine if the struct contains a
      "text" or "e_text" member. This compiles and links against
      MIT Kerberos or against Heimdal.

Ulrich

[-- Attachment #2: emacs-22.2-pop-heimdal.patch --]
[-- Type: text/plain, Size: 1906 bytes --]

--- emacs-22.2-orig/configure.in	2008-04-02 18:28:37.000000000 +0200
+++ emacs-22.2/configure.in	2008-04-02 22:18:38.000000000 +0200
@@ -2700,7 +2700,9 @@
   fi
 
   if test "${with_kerberos5+set}" = set; then
-    AC_CHECK_HEADERS(krb5.h)
+    AC_CHECK_HEADERS(krb5.h,
+      AC_CHECK_MEMBERS([krb5_error.text, krb5_error.e_text],,,
+		       [#include <krb5.h>]))
   else
     AC_CHECK_HEADERS(des.h,,
 		     [AC_CHECK_HEADERS(kerberosIV/des.h,,
--- emacs-22.2-orig/lib-src/pop.c	2008-02-23 14:49:00.000000000 +0100
+++ emacs-22.2/lib-src/pop.c	2008-04-02 22:35:55.000000000 +0200
@@ -1200,11 +1200,12 @@
       krb5_free_principal (kcontext, server);
       if (rem)
 	{
+	  strcpy (pop_error, KRB_ERROR);
+	  strncat (pop_error, error_message (rem),
+		   ERROR_MAX - sizeof (KRB_ERROR));
+#if defined HAVE_KRB5_ERROR_TEXT
 	  if (err_ret && err_ret->text.length)
 	    {
-	      strcpy (pop_error, KRB_ERROR);
-	      strncat (pop_error, error_message (rem),
-		       ERROR_MAX - sizeof (KRB_ERROR));
 	      strncat (pop_error, " [server says '",
 		       ERROR_MAX - strlen (pop_error) - 1);
 	      strncat (pop_error, err_ret->text.data,
@@ -1213,12 +1214,17 @@
 	      strncat (pop_error, "']",
 		       ERROR_MAX - strlen (pop_error) - 1);
 	    }
-	  else
+#elif defined HAVE_KRB5_ERROR_E_TEXT
+	  if (err_ret && err_ret->e_text && strlen(*err_ret->e_text))
 	    {
-	      strcpy (pop_error, KRB_ERROR);
-	      strncat (pop_error, error_message (rem),
-		       ERROR_MAX - sizeof (KRB_ERROR));
+	      strncat (pop_error, " [server says '",
+		       ERROR_MAX - strlen (pop_error) - 1);
+	      strncat (pop_error, *err_ret->e_text,
+		       ERROR_MAX - strlen (pop_error) - 1);
+	      strncat (pop_error, "']",
+		       ERROR_MAX - strlen (pop_error) - 1);
 	    }
+#endif
 	  if (err_ret)
 	    krb5_free_error (kcontext, err_ret);
 	  krb5_auth_con_free (kcontext, auth_context);