Used gsskrb5_register_acceptor_identity() to specify the keytab (some installations...
[mod_auth_kerb.cvs/.git] / src / mod_auth_kerb.c
index ab77c58..56e7297 100644 (file)
  *   Ludek Sulak <xsulak@fi.muni.cz>
  */
 
-/* ====================================================================
- * The Apache Software License, Version 1.1
- *
- * Copyright (c) 2000-2003 The Apache Software Foundation.  All rights
- * reserved.
+/*
+ * Copyright (c) 2004 Masarykova universita
+ * (Masaryk University, Brno, Czech Republic)
+ * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
+ * modification, are permitted provided that the following conditions are met:
  *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * 3. The end-user documentation included with the redistribution,
- *    if any, must include the following acknowledgment:
- *       "This product includes software developed by the
- *        Apache Software Foundation (http://www.apache.org/)."
- *    Alternately, this acknowledgment may appear in the software itself,
- *    if and wherever such third-party acknowledgments normally appear.
- *
- * 4. The names "Apache" and "Apache Software Foundation" must
- *    not be used to endorse or promote products derived from this
- *    software without prior written permission. For written
- *    permission, please contact apache@apache.org.
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
  *
- * 5. Products derived from this software may not be called "Apache",
- *    nor may "Apache" appear in their name, without prior written
- *    permission of the Apache Software Foundation.
+ * 3. Neither the name of the University nor the names of its contributors may
+ *    be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
  *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation.  For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- *
- * Portions of this software are based upon public domain software
- * originally written at the National Center for Supercomputing Applications,
- * University of Illinois, Urbana-Champaign.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ident "$Id$"
 
-#define MODAUTHKERB_VERSION "5.0-rc2"
+#include "config.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#define MODAUTHKERB_VERSION "5.0-rc6"
+#define MECH_NEGOTIATE "Negotiate"
 
-#ifndef APXS1
-#include "ap_compat.h"
-#include "apr_strings.h"
+#include <httpd.h>
+#include <http_config.h>
+#include <http_core.h>
+#include <http_log.h>
+#include <http_protocol.h>
+#include <http_request.h>
+
+#ifdef STANDARD20_MODULE_STUFF
+#include <ap_compat.h>
+#include <apr_strings.h>
+#include <apr_base64.h>
 #endif
-#include "httpd.h"
-#include "http_config.h"
-#include "http_core.h"
-#include "http_log.h"
-#include "http_protocol.h"
-#include "http_request.h"
 
 #ifdef KRB5
 #include <krb5.h>
 #else
 #  include <gssapi/gssapi.h>
 #  include <gssapi/gssapi_generic.h>
+#  include <gssapi/gssapi_krb5.h>
 #  define GSS_C_NT_USER_NAME gss_nt_user_name
 #  define GSS_C_NT_HOSTBASED_SERVICE gss_nt_service_name
 #  define krb5_get_err_text(context,code) error_message(code)
 #endif
+#include "spnegokrb5.h"
 #endif /* KRB5 */
 
 #ifdef KRB4
-/*Prevent warning about closesocket redefinition (Apache's ap_config.h and 
+/* Prevent warning about closesocket redefinition (Apache's ap_config.h and 
  * MIT Kerberos' port-sockets.h both define it as close) */
 #ifdef closesocket
 #  undef closesocket
 #include <netdb.h> /* gethostbyname() */
 #endif /* KRB4 */
 
-#ifdef APXS1
-module auth_kerb_module;
+#ifdef WIN32
+#define vsnprintf _vsnprintf
+#define snprintf _snprintf
 #else
+/* XXX remove dependency on unistd.h ??? */
+#include <unistd.h>
+#endif
+
+#ifdef STANDARD20_MODULE_STUFF
 module AP_MODULE_DECLARE_DATA auth_kerb_module;
+#else
+module auth_kerb_module;
 #endif
 
 /*************************************************************************** 
  Macros To Ease Compatibility
  ***************************************************************************/
-#ifdef APXS1
-#define MK_POOL pool
-#define MK_TABLE_GET ap_table_get
-#define MK_TABLE_SET ap_table_set
-#define MK_TABLE_TYPE table
-#define MK_PSTRDUP ap_pstrdup
-#define MK_USER r->connection->user
-#define MK_AUTH_TYPE r->connection->ap_auth_type
-#define MK_ARRAY_HEADER array_header
-#else
+#ifdef STANDARD20_MODULE_STUFF
 #define MK_POOL apr_pool_t
 #define MK_TABLE_GET apr_table_get
-#define MK_TABLE_SET apr_table_set
-#define MK_TABLE_TYPE apr_table_t
-#define MK_PSTRDUP apr_pstrdup
 #define MK_USER r->user
 #define MK_AUTH_TYPE r->ap_auth_type
-#define MK_ARRAY_HEADER apr_array_header_t
-#endif /* APXS1 */
-
+#else
+#define MK_POOL pool
+#define MK_TABLE_GET ap_table_get
+#define MK_USER r->connection->user
+#define MK_AUTH_TYPE r->connection->ap_auth_type
+#define PROXYREQ_PROXY STD_PROXY
+#endif
 
 /*************************************************************************** 
  Auth Configuration Structure
@@ -142,6 +127,10 @@ module AP_MODULE_DECLARE_DATA auth_kerb_module;
 typedef struct {
        char *krb_auth_realms;
        int krb_save_credentials;
+       int krb_verify_kdc;
+       char *krb_service_name;
+       int krb_authoritative;
+       int krb_delegate_basic;
 #ifdef KRB5
        char *krb_5_keytab;
        int krb_method_gssapi;
@@ -153,19 +142,23 @@ typedef struct {
 #endif
 } kerb_auth_config;
 
+static void
+set_kerb_auth_headers(request_rec *r, const kerb_auth_config *conf,
+                      int use_krb4, int use_krb5pwd, char *negotiate_ret_value);
+
 static const char*
 krb5_save_realms(cmd_parms *cmd, kerb_auth_config *sec, char *arg);
 
-#ifdef APXS1
+#ifdef STANDARD20_MODULE_STUFF
+#define command(name, func, var, type, usage)           \
+  AP_INIT_ ## type (name, func,                         \
+        (void*)APR_XtOffsetOf(kerb_auth_config, var),   \
+        OR_AUTHCFG | RSRC_CONF, usage)
+#else
 #define command(name, func, var, type, usage)          \
   { name, func,                                        \
     (void*)XtOffsetOf(kerb_auth_config, var),          \
-    OR_AUTHCFG, type, usage }
-#else
-#define command(name, func, var, type, usage)          \
-  AP_INIT_ ## type (name, func,                        \
-       (void*)APR_XtOffsetOf(kerb_auth_config, var),   \
-       OR_AUTHCFG, usage)
+    OR_AUTHCFG | RSRC_CONF, type, usage }
 #endif
 
 static const command_rec kerb_auth_cmds[] = {
@@ -178,6 +171,18 @@ static const command_rec kerb_auth_cmds[] = {
    command("KrbSaveCredentials", ap_set_flag_slot, krb_save_credentials,
      FLAG, "Save and store credentials/tickets retrieved during auth."),
 
+   command("KrbVerifyKDC", ap_set_flag_slot, krb_verify_kdc,
+     FLAG, "Verify tickets against keytab to prevent KDC spoofing attacks."),
+
+   command("KrbServiceName", ap_set_string_slot, krb_service_name,
+     TAKE1, "Service name to be used by Apache for authentication."),
+
+   command("KrbAuthoritative", ap_set_flag_slot, krb_authoritative,
+     FLAG, "Set to 'off' to allow access control to be passed along to lower modules iff the UserID is not known to this module."),
+
+   command("KrbDelegateBasic", ap_set_flag_slot, krb_delegate_basic,
+     FLAG, "Always offer Basic authentication regardless of KrbMethodK5Pass and pass on authentication to lower modules if Basic headers arrive."),
+
 #ifdef KRB5
    command("Krb5Keytab", ap_set_file_slot, krb_5_keytab,
      TAKE1, "Location of Kerberos V5 keytab file."),
@@ -185,7 +190,7 @@ static const command_rec kerb_auth_cmds[] = {
    command("KrbMethodNegotiate", ap_set_flag_slot, krb_method_gssapi,
      FLAG, "Enable Negotiate authentication method."),
 
-   command("KrbMethodK5Pass", ap_set_flag_slot, krb_method_k5pass,
+   command("KrbMethodK5Passwd", ap_set_flag_slot, krb_method_k5pass,
      FLAG, "Enable Kerberos V5 password authentication."),
 #endif 
 
@@ -193,20 +198,74 @@ static const command_rec kerb_auth_cmds[] = {
    command("Krb4Srvtab", ap_set_file_slot, krb_4_srvtab,
      TAKE1, "Location of Kerberos V4 srvtab file."),
 
-   command("KrbMethodK4Pass", ap_set_flag_slot, krb_method_k4pass,
+   command("KrbMethodK4Passwd", ap_set_flag_slot, krb_method_k4pass,
      FLAG, "Enable Kerberos V4 password authentication."),
 #endif
 
    { NULL }
 };
 
-#ifdef KRB5
-typedef struct {
-   gss_ctx_id_t context;
-   gss_cred_id_t server_creds;
-} gss_connection_t;
+#ifdef WIN32
+int
+mkstemp(char *template)
+{
+    int start, i;
+    pid_t val;
+    val = getpid();
+    start = strlen(template) - 1;
+    while(template[start] == 'X') {
+       template[start] = '0' + val % 10;
+       val /= 10;
+       start--;
+    }
+    
+    do{
+       int fd;
+       fd = open(template, O_RDWR | O_CREAT | O_EXCL, 0600);
+       if(fd >= 0 || errno != EEXIST)
+           return fd;
+       i = start + 1;
+       do{
+           if(template[i] == 0)
+               return -1;
+           template[i]++;
+           if(template[i] == '9' + 1)
+               template[i] = 'a';
+           if(template[i] <= 'z')
+               break;
+           template[i] = 'a';
+           i++;
+       }while(1);
+    }while(1);
+}
+#endif
+
+#if defined(KRB5) && !defined(HEIMDAL)
+/* Needed to work around problems with replay caches */
+#include "mit-internals.h"
+
+/* This is our replacement krb5_rc_store function */
+static krb5_error_code
+mod_auth_kerb_rc_store(krb5_context context, krb5_rcache rcache,
+                       krb5_donot_replay_internal *donot_replay)
+{
+   return 0;
+}
 
-static gss_connection_t *gss_connection = NULL;
+/* And this is the operations vector for our replay cache */
+const krb5_rc_ops_internal mod_auth_kerb_rc_ops = {
+  0,
+  "dfl",
+  krb5_rc_dfl_init,
+  krb5_rc_dfl_recover,
+  krb5_rc_dfl_destroy,
+  krb5_rc_dfl_close,
+  mod_auth_kerb_rc_store,
+  krb5_rc_dfl_expunge,
+  krb5_rc_dfl_get_span,
+  krb5_rc_dfl_get_name,
+  krb5_rc_dfl_resolve
+};
 #endif
 
 
@@ -218,6 +277,10 @@ static void *kerb_dir_create_config(MK_POOL *p, char *d)
        kerb_auth_config *rec;
 
        rec = (kerb_auth_config *) ap_pcalloc(p, sizeof(kerb_auth_config));
+        ((kerb_auth_config *)rec)->krb_verify_kdc = 1;
+       ((kerb_auth_config *)rec)->krb_service_name = "HTTP";
+       ((kerb_auth_config *)rec)->krb_authoritative = 1;
+       ((kerb_auth_config *)rec)->krb_delegate_basic = 0;
 #ifdef KRB5
        ((kerb_auth_config *)rec)->krb_method_k5pass = 1;
        ((kerb_auth_config *)rec)->krb_method_gssapi = 1;
@@ -245,10 +308,11 @@ void log_rerror(const char *file, int line, int level, int status,
    vsnprintf(errstr, sizeof(errstr), fmt, ap);
    va_end(ap);
 
-#ifdef APXS1
-   ap_log_rerror(file, line, level, r, "%s", errstr);
+   
+#ifdef STANDARD20_MODULE_STUFF
+   ap_log_rerror(file, line, level | APLOG_NOERRNO, status, r, "%s", errstr);
 #else
-   ap_log_rerror(file, line, level, status, r, "%s", errstr);
+   ap_log_rerror(file, line, level | APLOG_NOERRNO, r, "%s", errstr);
 #endif
 }
 
@@ -258,7 +322,7 @@ void log_rerror(const char *file, int line, int level, int status,
  ***************************************************************************/
 static int
 verify_krb4_user(request_rec *r, char *name, char *instance, char *realm,
-                char *password, char *linstance, char *srvtab)
+                char *password, char *linstance, char *srvtab, int krb_verify_kdc)
 {
    int ret;
    char *phost;
@@ -271,8 +335,14 @@ verify_krb4_user(request_rec *r, char *name, char *instance, char *realm,
 
    ret = krb_get_pw_in_tkt(name, instance, realm, "krbtgt", realm, 
                           DEFAULT_TKT_LIFE, password);
-   if (ret)
-      /* log(krb_err_txt[ret]) */
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "Cannot get krb4 ticket: krb_get_pw_in_tkt() failed: %s",
+                krb_get_err_text(ret));
+      return ret;
+   }
+
+   if (!krb_verify_kdc)
       return ret;
 
    hostname = ap_get_server_name(r);
@@ -280,6 +350,9 @@ verify_krb4_user(request_rec *r, char *name, char *instance, char *realm,
    hp = gethostbyname(hostname);
    if (hp == NULL) {
       dest_tkt();
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "Cannot verify krb4 ticket: gethostbyname() failed: %s",
+                hstrerror(h_errno));
       return h_errno;
    }
    memcpy(&addr, hp->h_addr, sizeof(addr));
@@ -290,13 +363,20 @@ verify_krb4_user(request_rec *r, char *name, char *instance, char *realm,
 
    ret = krb_mk_req(&ticket, linstance, phost, lrealm, 0);
    if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "Cannot verify krb4 ticket: krb_mk_req() failed: %s",
+                krb_get_err_text(ret));
       dest_tkt();
       return ret;
    }
 
    ret = krb_rd_req(&ticket, linstance, phost, addr, &authdata, srvtab);
-   if (ret)
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "Cannot verify krb4 ticket: krb_rd_req() failed: %s",
+                krb_get_err_text(ret));
       dest_tkt();
+   }
 
    return ret;
 }
@@ -327,6 +407,7 @@ authenticate_user_krb4pwd(request_rec *r,
    const char *realm;
    char *user;
    char lrealm[REALM_SZ];
+   int all_principals_unkown;
 
    sent_pw = ap_pbase64decode(r->pool, auth_line);
    sent_name = ap_getword (r->pool, &sent_pw, ':');
@@ -357,6 +438,7 @@ authenticate_user_krb4pwd(request_rec *r,
 
    krb_set_tkt_string(tkt_file);
 
+   all_principals_unkown = 1;
    realms = conf->krb_auth_realms;
    do {
       memset(lrealm, 0, sizeof(lrealm));
@@ -366,23 +448,32 @@ authenticate_user_krb4pwd(request_rec *r,
 
       if (realm == NULL) {
         ret = krb_get_lrealm(lrealm, 1);
+        if (ret)
+           break;
         realm = lrealm;
       }
-      if (realm == NULL || *realm == '\0')
-        break;
 
       ret = verify_krb4_user(r, (char *)sent_name, 
                             (sent_instance) ? sent_instance : "",
-                            (char *)realm, (char *)sent_pw, "khttp",
-                            conf->krb_4_srvtab);
+                            (char *)realm, (char *)sent_pw,
+                            conf->krb_service_name,
+                            conf->krb_4_srvtab, conf->krb_verify_kdc);
+      if (!conf->krb_authoritative && ret) {
+        /* if we're not authoritative, we allow authentication to pass on
+         * to another modules if (and only if) the user is not known to us */
+        if (all_principals_unkown && ret != KDC_PR_UNKNOWN)
+           all_principals_unkown = 0;
+      }
+
       if (ret == 0)
         break;
    } while (realms && *realms);
 
    if (ret) {
-      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-                "Verifying krb4 password failed (%d)", ret);
-      ret = HTTP_UNAUTHORIZED;
+      /* XXX log only in the verify_krb4_user() call */
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r, "Verifying krb4 password failed");
+      ret = (!conf->krb_authoritative && all_principals_unkown == 1 && ret == KDC_PR_UNKNOWN) ?
+                DECLINED : HTTP_UNAUTHORIZED;
       goto end;
    }
 
@@ -412,47 +503,224 @@ end:
 /*************************************************************************** 
  Username/Password Validation for Krb5
  ***************************************************************************/
+
+/* MIT kerberos uses replay cache checks even during credential verification
+ * (i.e. in krb5_verify_init_creds()), which is obviosuly useless. In order to
+ * avoid problems with multiple apache processes accessing the same rcache file
+ * we had to use this call instead, which is only a bit modified version of
+ * krb5_verify_init_creds() */
+static krb5_error_code
+verify_krb5_init_creds(request_rec *r, krb5_context context, krb5_creds *creds,
+                       krb5_principal ap_req_server, krb5_keytab ap_req_keytab)
+{
+   krb5_error_code ret;
+   krb5_data req;
+   krb5_ccache local_ccache = NULL;
+   krb5_creds *new_creds = NULL;
+   krb5_auth_context auth_context = NULL;
+   krb5_keytab keytab = NULL;
+   char *server_name;
+
+   memset(&req, 0, sizeof(req));
+
+   if (ap_req_keytab == NULL) {
+      ret = krb5_kt_default (context, &keytab);
+      if (ret)
+        return ret;
+   } else
+      keytab = ap_req_keytab;
+
+   ret = krb5_cc_resolve(context, "MEMORY:", &local_ccache);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                "krb5_cc_resolve() failed when verifying KDC");
+      return ret;
+   }
+
+   ret = krb5_cc_initialize(context, local_ccache, creds->client);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                "krb5_cc_initialize() failed when verifying KDC");
+      goto end;
+   }
+
+   ret = krb5_cc_store_cred (context, local_ccache, creds);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                "krb5_cc_initialize() failed when verifying KDC");
+      goto end;
+   }
+   
+   ret = krb5_unparse_name(context, ap_req_server, &server_name);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                "krb5_unparse_name() failed when verifying KDC");
+      goto end;
+   }
+   log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+             "Trying to verify authenticity of KDC using principal %s", server_name);
+   free(server_name);
+
+   if (!krb5_principal_compare (context, ap_req_server, creds->server)) {
+      krb5_creds match_cred;
+
+      memset (&match_cred, 0, sizeof(match_cred));
+
+      match_cred.client = creds->client;
+      match_cred.server = ap_req_server;
+
+      ret = krb5_get_credentials (context, 0, local_ccache, 
+                                 &match_cred, &new_creds);
+      if (ret) {
+        log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                   "krb5_get_credentials() failed when verifying KDC");
+        goto end;
+      }
+      creds = new_creds;
+   }
+
+   ret = krb5_mk_req_extended (context, &auth_context, 0, NULL, creds, &req);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                "krb5_mk_req_extended() failed when verifying KDC");
+      goto end;
+   }
+
+   krb5_auth_con_free (context, auth_context);
+   auth_context = NULL;
+   ret = krb5_auth_con_init(context, &auth_context);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                "krb5_auth_con_init() failed when verifying KDC");
+      goto end;
+   }
+   /* use KRB5_AUTH_CONTEXT_DO_SEQUENCE to skip replay cache checks */
+   krb5_auth_con_setflags(context, auth_context, KRB5_AUTH_CONTEXT_DO_SEQUENCE);
+
+   ret = krb5_rd_req (context, &auth_context, &req, ap_req_server,
+                     keytab, 0, NULL);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                "krb5_rd_req() failed when verifying KDC");
+      goto end;
+   }
+
+end:
+#ifdef HEIMDAL
+   /* XXX Do I ever want to support Heimdal 0.4 ??? */
+   krb5_data_free(&req);
+#else
+   krb5_free_data_contents(context, &req);
+#endif
+   if (auth_context)
+      krb5_auth_con_free (context, auth_context);
+   if (new_creds)
+      krb5_free_creds (context, new_creds);
+   if (ap_req_keytab == NULL && keytab)
+      krb5_kt_close (context, keytab);
+   if (local_ccache)
+      krb5_cc_destroy (context, local_ccache);
+
+   return ret;
+}
+
 /* Inspired by krb5_verify_user from Heimdal */
 static krb5_error_code
 verify_krb5_user(request_rec *r, krb5_context context, krb5_principal principal,
-                krb5_ccache ccache, const char *password, const char *service,
-                krb5_keytab keytab)
+                const char *password, const char *service, krb5_keytab keytab,
+                int krb_verify_kdc, krb5_ccache *ccache)
 {
    krb5_creds creds;
    krb5_principal server = NULL;
    krb5_error_code ret;
-   krb5_verify_init_creds_opt opt;
+   krb5_ccache ret_ccache = NULL;
+   char *name = NULL;
+
+   /* XXX error messages shouldn't be logged here (and in the while() loop in
+    * authenticate_user_krb5pwd() as weell), in order to avoid confusing log
+    * entries when using multiple realms */
 
    memset(&creds, 0, sizeof(creds));
 
+   ret = krb5_unparse_name(context, principal, &name);
+   if (ret == 0) {
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                "Trying to get TGT for user %s", name);
+      free(name);
+   }
+
    ret = krb5_get_init_creds_password(context, &creds, principal, 
-                                     (char *)password, krb5_prompter_posix,
+                                     (char *)password, NULL,
                                      NULL, 0, NULL, NULL);
-   if (ret)
-      return ret;
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "krb5_get_init_creds_password() failed: %s",
+                krb5_get_err_text(context, ret));
+      goto end;
+   }
 
    ret = krb5_sname_to_principal(context, ap_get_server_name(r), service, 
                                 KRB5_NT_SRV_HST, &server);
-   if (ret)
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "krb5_sname_to_principal() failed: %s",
+                krb5_get_err_text(context, ret));
       goto end;
+   }
+   /* XXX log_debug: lookig for <server_princ> in keytab */
 
-   krb5_verify_init_creds_opt_init(&opt);
-   krb5_verify_init_creds_opt_set_ap_req_nofail(&opt, 1);
+   /* XXX
+   {
+      char *realm;
 
-   ret = krb5_verify_init_creds(context, &creds, server, keytab, NULL, &opt);
-   if (ret)
+      krb5_get_default_realm(context, &realm);
+      log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                 "trying to verify password using key for %s/%s@%s",
+                service, ap_get_server_name(r), realm);
+   }
+   */
+
+   if (krb_verify_kdc &&
+       (ret = verify_krb5_init_creds(r, context, &creds, server, keytab))) {
+       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                 "failed to verify krb5 credentials: %s",
+                 krb5_get_err_text(context, ret));
+       goto end;
+   }
+
+   ret = krb5_cc_resolve(context, "MEMORY:", &ret_ccache);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r, 
+                "generating new memory ccache failed: %s",
+                krb5_get_err_text(context, ret));
       goto end;
+   }
 
-   if (ccache) {
-      ret = krb5_cc_initialize(context, ccache, principal);
-      if (ret == 0)
-        ret = krb5_cc_store_cred(context, ccache, &creds);
+   ret = krb5_cc_initialize(context, ret_ccache, principal);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "krb5_cc_initialize() failed: %s",
+                krb5_get_err_text(context, ret));
+      goto end;
+   }
+
+   ret = krb5_cc_store_cred(context, ret_ccache, &creds);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "krb5_cc_store_cred() failed: %s",
+                krb5_get_err_text(context, ret));
+      goto end;
    }
+   *ccache = ret_ccache;
+   ret_ccache = NULL;
 
 end:
    krb5_free_cred_contents(context, &creds);
    if (server)
       krb5_free_principal(context, server);
+   if (ret_ccache)
+      krb5_cc_destroy(context, ret_ccache);
+
    return ret;
 }
 
@@ -491,27 +759,30 @@ create_krb5_ccache(krb5_context kcontext,
                   krb5_ccache *ccache)
 {
    char *ccname;
+   int fd;
    krb5_error_code problem;
    int ret;
    krb5_ccache tmp_ccache = NULL;
 
-#ifdef HEIMDAL
-   problem = krb5_cc_gen_new(kcontext, &krb5_fcc_ops, &tmp_ccache);
-#else
-   problem = krb5_fcc_generate_new(kcontext, &tmp_ccache);
-   /* krb5_fcc_generate_new() doesn't set KRB5_TC_OPENCLOSE, which makes 
-      krb5_cc_initialize() fail */
-   krb5_fcc_set_flags(kcontext, tmp_ccache, KRB5_TC_OPENCLOSE);
-#endif
-   if (problem) {
+   ccname = ap_psprintf(r->pool, "FILE:%s/krb5cc_apache_XXXXXX", P_tmpdir);
+   fd = mkstemp(ccname + strlen("FILE:"));
+   if (fd < 0) {
       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-                "Cannot create file for new krb5 ccache: %s",
-                krb5_get_err_text(kcontext, problem));
+                 "mkstemp() failed: %s", strerror(errno));
       ret = HTTP_INTERNAL_SERVER_ERROR;
       goto end;
    }
+   close(fd);
 
-   ccname = ap_pstrdup(r->pool, krb5_cc_get_name(kcontext, tmp_ccache));
+   problem = krb5_cc_resolve(kcontext, ccname, &tmp_ccache);
+   if (problem) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                 "krb5_cc_resolve() failed: %s",
+                 krb5_get_err_text(kcontext, problem));
+      ret = HTTP_INTERNAL_SERVER_ERROR;
+      unlink(ccname);
+      goto end;
+   }
 
    problem = krb5_cc_initialize(kcontext, tmp_ccache, princ);
    if (problem) {
@@ -588,13 +859,15 @@ int authenticate_user_krb5pwd(request_rec *r,
    const char      *sent_pw = NULL; 
    const char      *sent_name = NULL;
    const char      *realms = NULL;
+   const char      *realm = NULL;
    krb5_context    kcontext = NULL;
    krb5_error_code code;
    krb5_principal  client = NULL;
    krb5_ccache     ccache = NULL;
    krb5_keytab     keytab = NULL;
    int             ret;
-   char *name = NULL;
+   char            *name = NULL;
+   int             all_principals_unkown;
 
    code = krb5_init_context(&kcontext);
    if (code) {
@@ -611,41 +884,48 @@ int authenticate_user_krb5pwd(request_rec *r,
                 "specifying realm in user name is prohibited");
       ret = HTTP_UNAUTHORIZED;
       goto end;
-   } 
+   }
 
-#ifdef HEIMDAL
-   code = krb5_cc_gen_new(kcontext, &krb5_mcc_ops, &ccache);
-#else
-   code = krb5_mcc_generate_new(kcontext, &ccache);
-#endif
-   if (code) {
-      log_rerror(APLOG_MARK, APLOG_ERR, 0, r, 
-                "Cannot generate new ccache: %s",
-                krb5_get_err_text(kcontext, code));
-      ret = HTTP_INTERNAL_SERVER_ERROR;
+   if (sent_pw == NULL || *sent_pw == '\0') {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "empty passwords are not accepted");
+      ret = HTTP_UNAUTHORIZED;
       goto end;
    }
 
    if (conf->krb_5_keytab)
       krb5_kt_resolve(kcontext, conf->krb_5_keytab, &keytab);
-      /* setenv("KRB5_KTNAME", conf->krb_5_keytab, 1); */
 
+   all_principals_unkown = 1;
    realms = conf->krb_auth_realms;
    do {
-      if (realms && (code = krb5_set_default_realm(kcontext,
-                                          ap_getword_white(r->pool, &realms))))
-        continue;
+      name = sent_name;
+      if (realms && (realm = ap_getword_white(r->pool, &realms)))
+        name = ap_psprintf(r->pool, "%s@%s", sent_name, realm);
 
       if (client) {
         krb5_free_principal(kcontext, client);
         client = NULL;
       }
-      code = krb5_parse_name(kcontext, sent_name, &client);
-      if (code)
+
+      code = krb5_parse_name(kcontext, name, &client);
+      if (code) {
+        log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                   "krb5_parse_name() failed: %s",
+                   krb5_get_err_text(kcontext, code));
         continue;
+      }
+
+      code = verify_krb5_user(r, kcontext, client, sent_pw, 
+                             conf->krb_service_name, 
+                             keytab, conf->krb_verify_kdc, &ccache);
+      if (!conf->krb_authoritative && code) {
+        /* if we're not authoritative, we allow authentication to pass on
+         * to another modules if (and only if) the user is not known to us */
+        if (all_principals_unkown && code != KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN)
+           all_principals_unkown = 0;
+      }
 
-      code = verify_krb5_user(r, kcontext, client, ccache, sent_pw, "khttp",
-                             keytab);
       if (code == 0)
         break;
 
@@ -656,10 +936,11 @@ int authenticate_user_krb5pwd(request_rec *r,
    memset((char *)sent_pw, 0, strlen(sent_pw));
 
    if (code) {
-      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-                "Verifying krb5 password failed: %s",
-                krb5_get_err_text(kcontext, code));
-      ret = HTTP_UNAUTHORIZED;
+      if (!conf->krb_authoritative && all_principals_unkown == 1 && code == KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN)
+        ret = DECLINED;
+      else
+        ret = HTTP_UNAUTHORIZED;
+
       goto end;
    }
 
@@ -680,6 +961,9 @@ int authenticate_user_krb5pwd(request_rec *r,
    ret = OK;
 
 end:
+   log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+             "kerb_authenticate_user_krb5pwd ret=%d user=%s authtype=%s",
+             ret, (MK_USER)?MK_USER:"(NULL)", (MK_AUTH_TYPE)?MK_AUTH_TYPE:"(NULL)");
    if (client)
       krb5_free_principal(kcontext, client);
    if (ccache)
@@ -696,50 +980,40 @@ end:
  ********************************************************************/
 
 static const char *
-get_gss_error(MK_POOL *p, OM_uint32 error_status, char *prefix)
+get_gss_error(MK_POOL *p, OM_uint32 err_maj, OM_uint32 err_min, char *prefix)
 {
-   OM_uint32 maj_stat, min_stat;
+   OM_uint32 maj_stat, min_stat; 
    OM_uint32 msg_ctx = 0;
    gss_buffer_desc status_string;
-   char buf[1024];
-   size_t len;
+   char *err_msg;
 
-   snprintf(buf, sizeof(buf), "%s", prefix);
-   len = strlen(buf);
+   err_msg = ap_pstrdup(p, prefix);
    do {
       maj_stat = gss_display_status (&min_stat,
-                                    error_status,
-                                    GSS_C_MECH_CODE,
+                                    err_maj,
+                                    GSS_C_GSS_CODE,
                                     GSS_C_NO_OID,
                                     &msg_ctx,
                                     &status_string);
-      if (sizeof(buf) > len + status_string.length + 1) {
-         sprintf(buf+len, ": %s", (char*) status_string.value);
-         len += status_string.length;
-      }
+      if (GSS_ERROR(maj_stat))
+        break;
+      err_msg = ap_pstrcat(p, err_msg, ": ", (char*) status_string.value, NULL);
       gss_release_buffer(&min_stat, &status_string);
+      
+      maj_stat = gss_display_status (&min_stat,
+                                    err_min,
+                                    GSS_C_MECH_CODE,
+                                    GSS_C_NULL_OID,
+                                    &msg_ctx,
+                                    &status_string);
+      if (!GSS_ERROR(maj_stat)) {
+        err_msg = ap_pstrcat(p, err_msg,
+                             " (", (char*) status_string.value, ")", NULL);
+        gss_release_buffer(&min_stat, &status_string);
+      }
    } while (!GSS_ERROR(maj_stat) && msg_ctx != 0);
 
-   return (ap_pstrdup(p, buf));
-}
-
-static int
-cleanup_gss_connection(void *data)
-{
-   OM_uint32 minor_status;
-   gss_connection_t *gss_conn = (gss_connection_t *)data;
-
-   if (data == NULL)
-      return OK;
-   if (gss_conn->context != GSS_C_NO_CONTEXT)
-      gss_delete_sec_context(&minor_status, &gss_conn->context,
-                            GSS_C_NO_BUFFER);
-   if (gss_conn->server_creds != GSS_C_NO_CREDENTIAL)
-      gss_release_cred(&minor_status, &gss_conn->server_creds);
-
-   gss_connection = NULL;
-
-   return OK;
+   return err_msg;
 }
 
 static int
@@ -777,7 +1051,7 @@ store_gss_creds(request_rec *r, kerb_auth_config *conf, char *princ_name,
    if (GSS_ERROR(maj_stat)) {
       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
         "Cannot store delegated credential (%s)", 
-        get_gss_error(r->pool, min_stat, "gss_krb5_copy_ccache"));
+        get_gss_error(r->pool, maj_stat, min_stat, "gss_krb5_copy_ccache"));
       goto end;
    }
 
@@ -799,25 +1073,41 @@ get_gss_creds(request_rec *r,
               kerb_auth_config *conf,
              gss_cred_id_t *server_creds)
 {
-   gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
+   gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
    OM_uint32 major_status, minor_status, minor_status2;
    gss_name_t server_name = GSS_C_NO_NAME;
    char buf[1024];
 
-   snprintf(buf, sizeof(buf), "%s/%s", "khttp", ap_get_server_name(r));
+   snprintf(buf, sizeof(buf), "%s@%s", conf->krb_service_name,
+           ap_get_server_name(r));
 
-   input_token.value = buf;
-   input_token.length = strlen(buf) + 1;
+   token.value = buf;
+   token.length = strlen(buf) + 1;
 
-   major_status = gss_import_name(&minor_status, &input_token,
-                                 GSS_C_NT_USER_NAME,
+   major_status = gss_import_name(&minor_status, &token,
+                                 GSS_C_NT_HOSTBASED_SERVICE,
                                  &server_name);
+   memset(&token, 0, sizeof(token));
    if (GSS_ERROR(major_status)) {
       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-                "%s", get_gss_error(r->pool, minor_status,
+                "%s", get_gss_error(r->pool, major_status, minor_status,
                 "gss_import_name() failed"));
       return HTTP_INTERNAL_SERVER_ERROR;
    }
+
+   major_status = gss_display_name(&minor_status, server_name, &token, NULL);
+   if (GSS_ERROR(major_status)) {
+      /* Perhaps we could just ignore this error but it's safer to give up now,
+         I think */
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "%s", get_gss_error(r->pool, major_status, minor_status,
+                                    "gss_display_name() failed"));
+      return HTTP_INTERNAL_SERVER_ERROR;
+   }
+
+   log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "Acquiring creds for %s",
+             token.value);
+   gss_release_buffer(&minor_status, &token);
    
    major_status = gss_acquire_cred(&minor_status, server_name, GSS_C_INDEFINITE,
                                   GSS_C_NO_OID_SET, GSS_C_ACCEPT,
@@ -825,18 +1115,65 @@ get_gss_creds(request_rec *r,
    gss_release_name(&minor_status2, &server_name);
    if (GSS_ERROR(major_status)) {
       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-                "%s", get_gss_error(r->pool, minor_status,
+                "%s", get_gss_error(r->pool, major_status, minor_status,
                                     "gss_acquire_cred() failed"));
       return HTTP_INTERNAL_SERVER_ERROR;
    }
+
+#ifndef HEIMDAL
+   /*
+    * With MIT Kerberos 5 1.3.x the gss_cred_id_t is the same as
+    * krb5_gss_cred_id_t and krb5_gss_cred_id_rec contains a pointer to
+    * the replay cache.
+    * This allows us to override the replay cache function vector with
+    * our own one.
+    * Note that this is a dirty hack to get things working and there may
+    * well be unknown side-effects.
+    */
+   {
+      krb5_gss_cred_id_t gss_creds = (krb5_gss_cred_id_t) *server_creds;
+
+      if (gss_creds && gss_creds->rcache && gss_creds->rcache->ops &&
+         gss_creds->rcache->ops->type &&  
+         memcmp(gss_creds->rcache->ops->type, "dfl", 3) == 0)
+          /* Override the rcache operations */
+        gss_creds->rcache->ops = &mod_auth_kerb_rc_ops;
+   }
+#endif
    
    return 0;
 }
 
 static int
-authenticate_user_gss(request_rec *r,
-                     kerb_auth_config *conf,
-                     const char *auth_line)
+cmp_gss_type(gss_buffer_t token, gss_OID oid)
+{
+   unsigned char *p;
+   size_t len;
+
+   if (token->length == 0)
+      return GSS_S_DEFECTIVE_TOKEN;
+
+   p = token->value;
+   if (*p++ != 0x60)
+      return GSS_S_DEFECTIVE_TOKEN;
+   len = *p++;
+   if (len & 0x80) {
+      if ((len & 0x7f) > 4)
+        return GSS_S_DEFECTIVE_TOKEN;
+      p += len & 0x7f;
+   }
+   if (*p++ != 0x06)
+      return GSS_S_DEFECTIVE_TOKEN;
+
+   if (((OM_uint32) *p++) != oid->length)
+      return GSS_S_DEFECTIVE_TOKEN;
+
+   return memcmp(p, oid->elements, oid->length);
+}
+
+static int
+authenticate_user_gss(request_rec *r, kerb_auth_config *conf,
+                     const char *auth_line, char **negotiate_ret_value)
 {
   OM_uint32 major_status, minor_status, minor_status2;
   gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
@@ -845,33 +1182,42 @@ authenticate_user_gss(request_rec *r,
   int ret;
   gss_name_t client_name = GSS_C_NO_NAME;
   gss_cred_id_t delegated_cred = GSS_C_NO_CREDENTIAL;
-  static int initial_return = HTTP_UNAUTHORIZED;
-
-  /* needed to work around replay caches */
-  if (!ap_is_initial_req(r))
-     return initial_return;
-  initial_return = HTTP_UNAUTHORIZED;
-
-  if (gss_connection == NULL) {
-     gss_connection = ap_pcalloc(r->connection->pool, sizeof(*gss_connection));
-     if (gss_connection == NULL) {
-       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-                  "ap_pcalloc() failed (not enough memory)");
+  OM_uint32 
+     (*accept_sec_token)(OM_uint32 *, gss_ctx_id_t *, const gss_cred_id_t,
+                        const gss_buffer_t, const gss_channel_bindings_t,
+                        gss_name_t *, gss_OID *, gss_buffer_t, OM_uint32 *,
+                        OM_uint32 *, gss_cred_id_t *);
+  gss_OID_desc spnego_oid;
+  gss_ctx_id_t context = GSS_C_NO_CONTEXT;
+  gss_cred_id_t server_creds = GSS_C_NO_CREDENTIAL;
+
+  *negotiate_ret_value = "\0";
+
+  spnego_oid.length = 6;
+  spnego_oid.elements = (void *)"\x2b\x06\x01\x05\x05\x02";
+
+  if (conf->krb_5_keytab) {
+     char *ktname;
+     /* we don't use the ap_* calls here, since the string passed to putenv()
+      * will become part of the enviroment and shouldn't be free()ed by apache
+      */
+     ktname = malloc(strlen("KRB5_KTNAME=") + strlen(conf->krb_5_keytab) + 1);
+     if (ktname == NULL) {
+       log_rerror(APLOG_MARK, APLOG_ERR, 0, r, "malloc() failed: not enough memory");
        ret = HTTP_INTERNAL_SERVER_ERROR;
        goto end;
      }
-     memset(gss_connection, 0, sizeof(*gss_connection));
-     ap_register_cleanup(r->connection->pool, gss_connection, cleanup_gss_connection, ap_null_cleanup);
+     sprintf(ktname, "KRB5_KTNAME=%s", conf->krb_5_keytab);
+     putenv(ktname);
+#ifdef HEIMDAL
+     /* Seems to be also supported by latest MIT */
+     gsskrb5_register_acceptor_identity(conf->krb_5_keytab);
+#endif
   }
 
-  if (conf->krb_5_keytab)
-     setenv("KRB5_KTNAME", conf->krb_5_keytab, 1);
-
-  if (gss_connection->server_creds == GSS_C_NO_CREDENTIAL) {
-     ret = get_gss_creds(r, conf, &gss_connection->server_creds);
-     if (ret)
-       goto end;
-  }
+  ret = get_gss_creds(r, conf, &server_creds);
+  if (ret)
+     goto end;
 
   /* ap_getword() shifts parameter */
   auth_param = ap_getword_white(r->pool, &auth_line);
@@ -892,22 +1238,28 @@ authenticate_user_gss(request_rec *r,
   }
   input_token.length = ap_base64decode(input_token.value, auth_param);
 
-#if 0 
-  major_status = gss_accept_sec_context(
-#else
-  major_status = gss_accept_sec_context_spnego(
-#endif
-                                       &minor_status,
-                                       &gss_connection->context,
-                                       gss_connection->server_creds,
-                                       &input_token,
-                                       GSS_C_NO_CHANNEL_BINDINGS,
-                                       &client_name,
-                                       NULL,
-                                       &output_token,
-                                       NULL,
-                                       NULL,
-                                       &delegated_cred);
+  accept_sec_token = (cmp_gss_type(&input_token, &spnego_oid) == 0) ?
+                       gss_accept_sec_context_spnego : gss_accept_sec_context;
+
+  /* pridat: Read client Negotiate data of length XXX, prefix YYY */
+  log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "Verifying client data using %s",
+            (accept_sec_token == gss_accept_sec_context)
+              ? "KRB5 GSS-API"
+              : "SPNEGO GSS-API");
+
+  major_status = accept_sec_token(&minor_status,
+                                 &context,
+                                 server_creds,
+                                 &input_token,
+                                 GSS_C_NO_CHANNEL_BINDINGS,
+                                 &client_name,
+                                 NULL,
+                                 &output_token,
+                                 NULL,
+                                 NULL,
+                                 &delegated_cred);
+  log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+            "Verification returned code %d", major_status);
   if (output_token.length) {
      char *token = NULL;
      size_t len;
@@ -923,42 +1275,56 @@ authenticate_user_gss(request_rec *r,
      }
      ap_base64encode(token, output_token.value, output_token.length);
      token[len] = '\0';
-     ap_table_set(r->err_headers_out, "WWW-Authenticate",
-                 ap_pstrcat(r->pool, "Negotiate ", token, NULL));
+     *negotiate_ret_value = token;
+     log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+               "GSS-API token of length %d bytes will be sent back",
+               output_token.length);
      gss_release_buffer(&minor_status2, &output_token);
   }
 
   if (GSS_ERROR(major_status)) {
+     if (input_token.length > 7 && memcmp(input_token.value, "NTLMSSP", 7) == 0)
+       log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                 "Warning: received token seems to be NTLM, which isn't supported by the Kerberos module. Check your IE configuration.");
+
      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-               "%s", get_gss_error(r->pool, minor_status,
+               "%s", get_gss_error(r->pool, major_status, minor_status,
                                    "gss_accept_sec_context() failed"));
+     /* Don't offer the Negotiate method again if call to GSS layer failed */
+     *negotiate_ret_value = NULL;
      ret = HTTP_UNAUTHORIZED;
      goto end;
   }
 
+#if 0
+  /* This is a _Kerberos_ module so multiple authentication rounds aren't
+   * supported. If we wanted a generic GSS authentication we would have to do
+   * some magic with exporting context etc. */
   if (major_status & GSS_S_CONTINUE_NEEDED) {
-     /* Some GSSAPI mechanism (eg GSI from Globus) may require multiple 
-      * iterations to establish authentication */
      ret = HTTP_UNAUTHORIZED;
      goto end;
   }
+#endif
 
   major_status = gss_display_name(&minor_status, client_name, &output_token, NULL);
   gss_release_name(&minor_status, &client_name); 
   if (GSS_ERROR(major_status)) {
     log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-              "%s", get_gss_error(r->pool, minor_status, 
+              "%s", get_gss_error(r->pool, major_status, minor_status,
                                   "gss_export_name() failed"));
     ret = HTTP_INTERNAL_SERVER_ERROR;
     goto end;
   }
 
-  MK_AUTH_TYPE = "Negotiate";
+  MK_AUTH_TYPE = MECH_NEGOTIATE;
   MK_USER = ap_pstrdup(r->pool, output_token.value);
 
   if (conf->krb_save_credentials && delegated_cred != GSS_C_NO_CREDENTIAL)
      store_gss_creds(r, conf, (char *)output_token.value, delegated_cred);
 
+  if (*negotiate_ret_value)
+     set_kerb_auth_headers(r, conf, 0, 0, *negotiate_ret_value);
+
   gss_release_buffer(&minor_status, &output_token);
 
   ret = OK;
@@ -973,39 +1339,60 @@ end:
   if (client_name != GSS_C_NO_NAME)
      gss_release_name(&minor_status, &client_name);
 
-  cleanup_gss_connection(gss_connection);
+  if (server_creds != GSS_C_NO_CREDENTIAL)
+     gss_release_cred(&minor_status, &server_creds);
+
+  if (context != GSS_C_NO_CONTEXT)
+     gss_delete_sec_context(&minor_status, &context, GSS_C_NO_BUFFER);
 
-  initial_return = ret;
   return ret;
 }
 #endif /* KRB5 */
 
+static int
+already_succeeded(request_rec *r)
+{
+   if (ap_is_initial_req(r) || MK_AUTH_TYPE == NULL)
+      return 0;
+   if (strcmp(MK_AUTH_TYPE, MECH_NEGOTIATE) ||
+       (strcmp(MK_AUTH_TYPE, "Basic") && strchr(MK_USER, '@')))
+      return 1;
+   return 0;
+}
 
 static void
-note_kerb_auth_failure(request_rec *r, const kerb_auth_config *conf,
-                      int use_krb4, int use_krb5)
+set_kerb_auth_headers(request_rec *r, const kerb_auth_config *conf,
+                     int use_krb4, int use_krb5pwd, char *negotiate_ret_value)
 {
    const char *auth_name = NULL;
    int set_basic = 0;
+   char *negoauth_param;
+   const char *header_name = 
+      (r->proxyreq == PROXYREQ_PROXY) ? "Proxy-Authenticate" : "WWW-Authenticate";
 
    /* get the user realm specified in .htaccess */
    auth_name = ap_auth_name(r);
 
-   /* XXX should the WWW-Authenticate header be cleared first? */
+   /* XXX should the WWW-Authenticate header be cleared first?
+    * apache in the proxy mode should retain client's authN headers? */
 #ifdef KRB5
-   if (use_krb5 && conf->krb_method_gssapi)
-      ap_table_add(r->err_headers_out, "WWW-Authenticate", "Negotiate ");
-   if (use_krb5 && conf->krb_method_k5pass) {
-      ap_table_add(r->err_headers_out, "WWW-Authenticate",
-                   ap_pstrcat(r->pool, "Basic realm=\"", auth_name, "\"", NULL));
+   if (negotiate_ret_value != NULL && conf->krb_method_gssapi) {
+      negoauth_param = (*negotiate_ret_value == '\0') ? MECH_NEGOTIATE :
+                 ap_pstrcat(r->pool, MECH_NEGOTIATE " ", negotiate_ret_value, NULL);
+      ap_table_add(r->err_headers_out, header_name, negoauth_param);
+   }
+   if ((use_krb5pwd && conf->krb_method_k5pass) || conf->krb_delegate_basic) {
+      ap_table_add(r->err_headers_out, header_name,
+                  ap_pstrcat(r->pool, "Basic realm=\"", auth_name, "\"", NULL));
       set_basic = 1;
    }
 #endif
 
 #ifdef KRB4
-   if (use_krb4 && conf->krb_method_k4pass && !set_basic)
-      ap_table_add(r->err_headers_out, "WWW-Authenticate",
-                  ap_pstrcat(r->pool, "Basic realm=\"", auth_name, "\"", NULL));
+   if (!set_basic && 
+       ((use_krb4 && conf->krb_method_k4pass) || conf->krb_delegate_basic))
+      ap_table_add(r->err_headers_out, header_name,
+                 ap_pstrcat(r->pool, "Basic realm=\"", auth_name, "\"", NULL));
 #endif
 }
 
@@ -1019,33 +1406,56 @@ int kerb_authenticate_user(request_rec *r)
    const char *type = NULL;
    int use_krb5 = 0, use_krb4 = 0;
    int ret;
+   static int last_return = HTTP_UNAUTHORIZED;
+   char *negotiate_ret_value = NULL;
 
    /* get the type specified in .htaccess */
    type = ap_auth_type(r);
 
+   log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+             "kerb_authenticate_user entered with user %s and auth_type %s",
+             (MK_USER)?MK_USER:"(NULL)",type?type:"(NULL)");
+
    if (type && strcasecmp(type, "Kerberos") == 0)
       use_krb5 = use_krb4 = 1;
    else if(type && strcasecmp(type, "KerberosV5") == 0)
-      use_krb4 = 0;
+      use_krb5 = 1;
    else if(type && strcasecmp(type, "KerberosV4") == 0)
-      use_krb5 = 0;
+      use_krb4 = 1;
    else
       return DECLINED;
 
    /* get what the user sent us in the HTTP header */
-   auth_line = MK_TABLE_GET(r->headers_in, "Authorization");
+   auth_line = MK_TABLE_GET(r->headers_in, (r->proxyreq == PROXYREQ_PROXY)
+                                           ? "Proxy-Authorization"
+                                           : "Authorization");
    if (!auth_line) {
-      note_kerb_auth_failure(r, conf, use_krb4, use_krb5);
+      set_kerb_auth_headers(r, conf, use_krb4, use_krb5, 
+                           (use_krb5) ? "\0" : NULL);
       return HTTP_UNAUTHORIZED;
    }
    auth_type = ap_getword_white(r->pool, &auth_line);
 
+   /* If we are delegating Basic to other modules, DECLINE the request */
+   if (conf->krb_delegate_basic &&
+#ifdef KRB5
+       !conf->krb_method_k5pass &&
+#endif
+#ifdef KRB4
+       !conf->krb_method_k4pass &&
+#endif
+       (strcasecmp(auth_type, "Basic") == 0))
+       return DECLINED;
+
+   if (already_succeeded(r))
+      return last_return;
+
    ret = HTTP_UNAUTHORIZED;
 
 #ifdef KRB5
    if (use_krb5 && conf->krb_method_gssapi &&
-       strcasecmp(auth_type, "Negotiate") == 0) {
-      ret = authenticate_user_gss(r, conf, auth_line);
+       strcasecmp(auth_type, MECH_NEGOTIATE) == 0) {
+      ret = authenticate_user_gss(r, conf, auth_line, &negotiate_ret_value);
    } else if (use_krb5 && conf->krb_method_k5pass &&
              strcasecmp(auth_type, "Basic") == 0) {
        ret = authenticate_user_krb5pwd(r, conf, auth_line);
@@ -1059,8 +1469,11 @@ int kerb_authenticate_user(request_rec *r)
 #endif
 
    if (ret == HTTP_UNAUTHORIZED)
-      note_kerb_auth_failure(r, conf, use_krb4, use_krb5);
+      set_kerb_auth_headers(r, conf, use_krb4, use_krb5, negotiate_ret_value);
+
+   /* XXX log_debug: if ret==OK, log(user XY authenticated) */
 
+   last_return = ret;
    return ret;
 }
 
@@ -1068,7 +1481,7 @@ int kerb_authenticate_user(request_rec *r)
 /*************************************************************************** 
  Module Setup/Configuration
  ***************************************************************************/
-#ifdef APXS1
+#ifndef STANDARD20_MODULE_STUFF
 module MODULE_VAR_EXPORT auth_kerb_module = {
        STANDARD_MODULE_STUFF,
        NULL,                           /*      module initializer            */
@@ -1089,6 +1502,12 @@ module MODULE_VAR_EXPORT auth_kerb_module = {
        NULL,                           /*      process initialization        */
        NULL,                           /*      process exit/cleanup          */
        NULL                            /* [ 1] post read_request handling    */
+#ifdef EAPI
+       ,NULL,                          /* EAPI: add_module                   */
+       NULL,                           /* EAPI: remove_module                */
+       NULL,                           /* EAPI: rewrite_command              */
+       NULL                            /* EAPI: new_connection               */
+#endif
 };
 #else
 static int