/**
 * xrdp: A Remote Desktop Protocol server.
 *
 * Copyright (C) Jay Sorg 2004-2013
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 *
 * @file verify_user_pam.c
 * @brief Authenticate user using pam
 * @author Jay Sorg
 *
 */

#if defined(HAVE_CONFIG_H)
#include <config_ac.h>
#endif

#include "arch.h"
#include "os_calls.h"

#include <stdio.h>
#include <security/pam_appl.h>

struct t_user_pass
{
    char user[256];
    char pass[256];
};

struct t_auth_info
{
    struct t_user_pass user_pass;
    int session_opened;
    int did_setcred;
    struct pam_conv pamc;
    pam_handle_t *ph;
};

/******************************************************************************/
static int
verify_pam_conv(int num_msg, const struct pam_message **msg,
                struct pam_response **resp, void *appdata_ptr)
{
    int i;
    struct pam_response *reply;
    struct t_user_pass *user_pass;

    reply = g_new0(struct pam_response, num_msg);

    for (i = 0; i < num_msg; i++)
    {
        switch (msg[i]->msg_style)
        {
            case PAM_PROMPT_ECHO_ON: /* username */
                user_pass = (struct t_user_pass *) appdata_ptr;
                reply[i].resp = g_strdup(user_pass->user);
                reply[i].resp_retcode = PAM_SUCCESS;
                break;
            case PAM_PROMPT_ECHO_OFF: /* password */
                user_pass = (struct t_user_pass *) appdata_ptr;
                reply[i].resp = g_strdup(user_pass->pass);
                reply[i].resp_retcode = PAM_SUCCESS;
                break;
            default:
                g_printf("unknown in verify_pam_conv\r\n");
                g_free(reply);
                return PAM_CONV_ERR;
        }
    }

    *resp = reply;
    return PAM_SUCCESS;
}

/******************************************************************************/
static void
get_service_name(char *service_name)
{
    service_name[0] = 0;

    if (g_file_exist("/etc/pam.d/xrdp-sesman") ||
        g_file_exist(XRDP_SYSCONF_PATH "/pam.d/xrdp-sesman"))
    {
        g_strncpy(service_name, "xrdp-sesman", 255);
    }
    else
    {
        g_strncpy(service_name, "gdm", 255);
    }
}

/******************************************************************************/
/* returns long, zero is no go
 Stores the detailed error code in the errorcode variable*/

long
auth_userpass(const char *user, const char *pass, int *errorcode)
{
    int error;
    struct t_auth_info *auth_info;
    char service_name[256];

    get_service_name(service_name);
    auth_info = g_new0(struct t_auth_info, 1);
    g_strncpy(auth_info->user_pass.user, user, 255);
    g_strncpy(auth_info->user_pass.pass, pass, 255);
    auth_info->pamc.conv = &verify_pam_conv;
    auth_info->pamc.appdata_ptr = &(auth_info->user_pass);
    error = pam_start(service_name, 0, &(auth_info->pamc), &(auth_info->ph));

    if (error != PAM_SUCCESS)
    {
        if (errorcode != NULL)
        {
            *errorcode = error;
        }
        g_printf("pam_start failed: %s\r\n", pam_strerror(auth_info->ph, error));
        pam_end(auth_info->ph, error);
        g_free(auth_info);
        return 0;
    }

    error = pam_set_item(auth_info->ph, PAM_TTY, service_name);
    if (error != PAM_SUCCESS)
    {
        g_printf("pam_set_item failed: %s\r\n",
                 pam_strerror(auth_info->ph, error));
    }

    error = pam_authenticate(auth_info->ph, 0);

    if (error != PAM_SUCCESS)
    {
        if (errorcode != NULL)
        {
            *errorcode = error;
        }
        g_printf("pam_authenticate failed: %s\r\n",
                 pam_strerror(auth_info->ph, error));
        pam_end(auth_info->ph, error);
        g_free(auth_info);
        return 0;
    }
    /* From man page:
       The pam_acct_mgmt function is used to determine if the users account is
       valid. It checks for authentication token and account expiration and
       verifies access restrictions. It is typically called after the user has
       been authenticated.
     */
    error = pam_acct_mgmt(auth_info->ph, 0);

    if (error != PAM_SUCCESS)
    {
        if (errorcode != NULL)
        {
            *errorcode = error;
        }
        g_printf("pam_acct_mgmt failed: %s\r\n",
                 pam_strerror(auth_info->ph, error));
        pam_end(auth_info->ph, error);
        g_free(auth_info);
        return 0;
    }

    return (long)auth_info;
}

/******************************************************************************/
/* returns error */
int
auth_start_session(long in_val, int in_display)
{
    struct t_auth_info *auth_info;
    int error;
    char display[256];

    g_sprintf(display, ":%d", in_display);
    auth_info = (struct t_auth_info *)in_val;
    error = pam_set_item(auth_info->ph, PAM_TTY, display);

    if (error != PAM_SUCCESS)
    {
        g_printf("pam_set_item failed: %s\r\n", pam_strerror(auth_info->ph, error));
        return 1;
    }

    error = pam_setcred(auth_info->ph, PAM_ESTABLISH_CRED);

    if (error != PAM_SUCCESS)
    {
        g_printf("pam_setcred failed: %s\r\n", pam_strerror(auth_info->ph, error));
        return 1;
    }

    auth_info->did_setcred = 1;
    error = pam_open_session(auth_info->ph, 0);

    if (error != PAM_SUCCESS)
    {
        g_printf("pam_open_session failed: %s\r\n",
                 pam_strerror(auth_info->ph, error));
        return 1;
    }

    auth_info->session_opened = 1;
    return 0;
}

/******************************************************************************/
/* returns error */
int
auth_stop_session(long in_val)
{
    struct t_auth_info *auth_info;
    int error;

    auth_info = (struct t_auth_info *)in_val;
    error = pam_close_session(auth_info->ph, 0);
    if (error != PAM_SUCCESS)
    {
        g_printf("pam_close_session failed: %s\r\n",
                 pam_strerror(auth_info->ph, error));
        return 1;
    }
    auth_info->session_opened = 0;
    return 0;
}

/******************************************************************************/
/* returns error */
/* cleanup */
int
auth_end(long in_val)
{
    struct t_auth_info *auth_info;

    auth_info = (struct t_auth_info *)in_val;

    if (auth_info != 0)
    {
        if (auth_info->ph != 0)
        {
            if (auth_info->session_opened)
            {
                pam_close_session(auth_info->ph, 0);
            }

            if (auth_info->did_setcred)
            {
                pam_setcred(auth_info->ph, PAM_DELETE_CRED);
            }

            pam_end(auth_info->ph, PAM_SUCCESS);
            auth_info->ph = 0;
        }
    }

    g_free(auth_info);
    return 0;
}

/******************************************************************************/
/* returns error */
/* set any pam env vars */
int
auth_set_env(long in_val)
{
    struct t_auth_info *auth_info;
    char **pam_envlist;
    char **pam_env;
    char item[256];
    char value[256];
    int eq_pos;

    auth_info = (struct t_auth_info *)in_val;

    if (auth_info != 0)
    {
        /* export PAM environment */
        pam_envlist = pam_getenvlist(auth_info->ph);

        if (pam_envlist != NULL)
        {
            for (pam_env = pam_envlist; *pam_env != NULL; ++pam_env)
            {
                eq_pos = g_pos(*pam_env, "=");

                if (eq_pos >= 0 && eq_pos < 250)
                {
                    g_strncpy(item, *pam_env, eq_pos);
                    g_strncpy(value, (*pam_env) + eq_pos + 1, 255);
                    g_setenv(item, value, 1);
                }

                g_free(*pam_env);
            }

            g_free(pam_envlist);
        }
    }

    return 0;
}