/**
 * xrdp: A Remote Desktop Protocol server.
 *
 * Copyright (C) Jay Sorg 2004-2012
 *
 * 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
 *
 */

#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 DEFAULT_CC
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_malloc(sizeof(struct pam_response) * num_msg, 1);

    for (i = 0; i < num_msg; i++)
    {
        switch (msg[i]->msg_style)
        {
            case PAM_PROMPT_ECHO_ON: /* username */
                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 = 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 DEFAULT_CC
get_service_name(char *service_name)
{
    service_name[0] = 0;

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

/******************************************************************************/
/* returns long, zero is no go */
long DEFAULT_CC
auth_userpass(char *user, char *pass)
{
    int error;
    struct t_auth_info *auth_info;
    char service_name[256];

    get_service_name(service_name);
    auth_info = g_malloc(sizeof(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)
    {
        g_printf("pam_start failed: %s\r\n", pam_strerror(auth_info->ph, error));
        g_free(auth_info);
        return 0;
    }

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

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

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

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

    return (long)auth_info;
}

/******************************************************************************/
/* returns error */
int DEFAULT_CC
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 */
/* cleanup */
int DEFAULT_CC
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 DEFAULT_CC
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;
}