PAM-specific auth functions.

+/* GNU mailutils - a suite of utilities for electronic mail
+   Copyright (C) 2002 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <pwd.h>
+#ifdef HAVE_SHADOW_H
+# include <shadow.h>
+#endif
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif
+#ifdef HAVE_SECURITY_PAM_APPL_H
+# include <security/pam_appl.h>
+#endif
+#ifdef HAVE_CRYPT_H
+# include <crypt.h>
+#endif
+
+#include <mailutils/list.h>
+#include <mailutils/iterator.h>
+#include <mailutils/mailbox.h>
+#include <mailutils/argp.h>
+#include <mailutils/mu_auth.h>
+
+char *pam_service = NULL;
+
+#ifdef USE_LIBPAM
+#define COPY_STRING(s) (s) ? strdup(s) : NULL
+
+static char *_pwd;
+static char *_user;
+static int _perr = 0;
+
+static int
+mu_pam_conv (int num_msg, const struct pam_message **msg,
+	     struct pam_response **resp, void *appdata_ptr)
+{
+  int replies = 0;
+  struct pam_response *reply = NULL;
+  (void)appdata_ptr;
+
+  reply = malloc (sizeof (*reply) * num_msg);
+  if (!reply)
+    return PAM_CONV_ERR;
+
+  for (replies = 0; replies < num_msg; replies++)
+    {
+      switch (msg[replies]->msg_style)
+	{
+	case PAM_PROMPT_ECHO_ON:
+	  reply[replies].resp_retcode = PAM_SUCCESS;
+	  reply[replies].resp = COPY_STRING (_user);
+	  /* PAM frees resp */
+	  break;
+
+	case PAM_PROMPT_ECHO_OFF:
+	  reply[replies].resp_retcode = PAM_SUCCESS;
+	  reply[replies].resp = COPY_STRING (_pwd);
+	  /* PAM frees resp */
+	  break;
+
+	case PAM_TEXT_INFO:
+	case PAM_ERROR_MSG:
+	  reply[replies].resp_retcode = PAM_SUCCESS;
+	  reply[replies].resp = NULL;
+	  break;
+ 
+	default:
+	  free (reply);
+	  _perr = 1;
+	  return PAM_CONV_ERR;
+	}
+    }
+  *resp = reply;
+  return PAM_SUCCESS;
+}
+
+static struct pam_conv PAM_conversation = { &mu_pam_conv, NULL };
+
+int
+mu_authenticate_pam (void *ignored_return_data,
+		     void *key,
+		     void *ignored_func_data,
+		     void *call_data)
+{
+  struct mu_auth_data *auth_data = key;
+  char *pass = call_data;
+  pam_handle_t *pamh;
+  int pamerror;
+
+#define PAM_ERROR if (_perr || (pamerror != PAM_SUCCESS)) \
+    goto pam_errlab;
+
+  if (!auth_data)
+    return 1;
+  
+  _user = (char *) auth_data->name;
+  _pwd = pass;
+  pamerror = pam_start (pam_service, _user, &PAM_conversation, &pamh);
+  PAM_ERROR;
+  pamerror = pam_authenticate (pamh, 0);
+  PAM_ERROR;
+  pamerror = pam_acct_mgmt (pamh, 0);
+  PAM_ERROR;
+  pamerror = pam_setcred (pamh, PAM_ESTABLISH_CRED);
+ pam_errlab:
+  pam_end (pamh, PAM_SUCCESS);
+  return pamerror != PAM_SUCCESS;
+}
+
+#define ARG_PAM_SERVICE 1
+
+static error_t
+mu_pam_argp_parser (int key, char *arg, struct argp_state *state)
+{
+  switch (key)
+    {
+    case ARG_PAM_SERVICE:
+      pam_service = arg;
+      break;
+
+    default:
+      return ARGP_ERR_UNKNOWN;
+    }
+  return 0;
+}
+
+static struct argp_option mu_pam_argp_option[] = {
+  { "pam-service", ARG_PAM_SERVICE, "STRING", 0,
+    "Use STRING as PAM service name", 0},
+    { NULL,      0, NULL, 0, NULL, 0 }
+};
+
+struct argp mu_pam_argp = {
+  mu_pam_argp_option,
+  mu_pam_argp_parser,
+};
+
+
+#else
+
+int
+mu_authenticate_pam (void *ignored_return_data,
+		     void *key,
+		     void *ignored_func_data,
+		     void *call_data)
+{
+  errno = ENOSYS;
+  return 1;
+}
+
+#endif
+  
+struct mu_auth_module mu_auth_pam_module = {
+  "pam",
+#ifdef USE_LIBPAM
+  &mu_pam_argp,
+#else
+  NULL,
+#endif
+  mu_authenticate_pam,
+  NULL,
+  mu_auth_nosupport,
+  NULL,
+  mu_auth_nosupport,
+  NULL
+};
+