/* 
 * Copyright (C) 2004 Andrew Beekhof <andrew@beekhof.net>
 * 
 * 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 of the License, or (at your option) any later version.
 * 
 * This software 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <crm_internal.h>
#include <crm/crm.h>

#include <sys/param.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#include <netinet/ip.h>

#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <glib.h>

#include <crm/common/ipc.h>
#include <crm/common/xml.h>
#include "callbacks.h"
/* #undef HAVE_PAM_PAM_APPL_H */
/* #undef HAVE_GNUTLS_GNUTLS_H */

#ifdef HAVE_GNUTLS_GNUTLS_H
#  undef KEYFILE
#  include <gnutls/gnutls.h>
#endif

#include <pwd.h>
#include <grp.h>
#if HAVE_SECURITY_PAM_APPL_H
#  include <security/pam_appl.h>
#  define HAVE_PAM 1
#else
#  if HAVE_PAM_PAM_APPL_H
#    include <pam/pam_appl.h>
#    define HAVE_PAM 1
#  endif
#endif

#ifdef HAVE_DECL_NANOSLEEP
#  include <time.h>
#endif

extern int remote_tls_fd;
extern gboolean cib_shutdown_flag;
extern void initiate_exit(void);

int init_remote_listener(int port, gboolean encrypted);
void cib_remote_connection_destroy(gpointer user_data);

#ifdef HAVE_GNUTLS_GNUTLS_H
#  define DH_BITS 1024
gnutls_dh_params dh_params;
extern gnutls_anon_server_credentials anon_cred_s;
static void
debug_log(int level, const char *str)
{
    fputs(str, stderr);
}

extern gnutls_session *create_tls_session(int csock, int type);

#endif

extern int num_clients;
int authenticate_user(const char *user, const char *passwd);
gboolean cib_remote_listen(int ssock, gpointer data);
gboolean cib_remote_msg(int csock, gpointer data);

extern void cib_common_callback_worker(xmlNode * op_request, cib_client_t * cib_client,
                                       gboolean force_synchronous, gboolean privileged);

#define ERROR_SUFFIX "  Shutting down remote listener"
int
init_remote_listener(int port, gboolean encrypted)
{
    int ssock;
    struct sockaddr_in saddr;
    int optval;

    if (port <= 0) {
        /* dont start it */
        return 0;
    }

    if (encrypted) {
#ifndef HAVE_GNUTLS_GNUTLS_H
        crm_warn("TLS support is not available");
        return 0;
#else
        crm_notice("Starting a tls listener on port %d.", port);
        gnutls_global_init();
/* 	gnutls_global_set_log_level (10); */
        gnutls_global_set_log_function(debug_log);
        gnutls_dh_params_init(&dh_params);
        gnutls_dh_params_generate2(dh_params, DH_BITS);
        gnutls_anon_allocate_server_credentials(&anon_cred_s);
        gnutls_anon_set_server_dh_params(anon_cred_s, dh_params);
#endif
    } else {
        crm_warn("Starting a plain_text listener on port %d.", port);
    }
#ifndef HAVE_PAM
    crm_warn("PAM is _not_ enabled!");
#endif

    /* create server socket */
    ssock = socket(AF_INET, SOCK_STREAM, 0);
    if (ssock == -1) {
        crm_perror(LOG_ERR, "Can not create server socket." ERROR_SUFFIX);
        return -1;
    }

    /* reuse address */
    optval = 1;
    setsockopt(ssock, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));

    /* bind server socket */
    memset(&saddr, '\0', sizeof(saddr));
    saddr.sin_family = AF_INET;
    saddr.sin_addr.s_addr = INADDR_ANY;
    saddr.sin_port = htons(port);
    if (bind(ssock, (struct sockaddr *)&saddr, sizeof(saddr)) == -1) {
        crm_perror(LOG_ERR, "Can not bind server socket." ERROR_SUFFIX);
        close(ssock);
        return -2;
    }
    if (listen(ssock, 10) == -1) {
        crm_perror(LOG_ERR, "Can not start listen." ERROR_SUFFIX);
        close(ssock);
        return -3;
    }

    G_main_add_fd(G_PRIORITY_HIGH, ssock, FALSE,
                  cib_remote_listen, NULL, default_ipc_connection_destroy);

    return ssock;
}

static int
check_group_membership(const char *usr, const char *grp)
{
    int index = 0;
    struct passwd *pwd = NULL;
    struct group *group = NULL;

    CRM_CHECK(usr != NULL, return FALSE);
    CRM_CHECK(grp != NULL, return FALSE);

    pwd = getpwnam(usr);
    if (pwd == NULL) {
        crm_err("No user named '%s' exists!", usr);
        return FALSE;
    }

    group = getgrgid(pwd->pw_gid);
    if (group != NULL && crm_str_eq(grp, group->gr_name, TRUE)) {
        return TRUE;
    }

    group = getgrnam(grp);
    if (group == NULL) {
        crm_err("No group named '%s' exists!", grp);
        return FALSE;
    }

    while (TRUE) {
        char *member = group->gr_mem[index++];

        if (member == NULL) {
            break;

        } else if (crm_str_eq(usr, member, TRUE)) {
            return TRUE;
        }
    };

    return FALSE;
}

gboolean
cib_remote_listen(int ssock, gpointer data)
{
    int lpc = 0;
    int csock = 0;
    unsigned laddr;
    time_t now = 0;
    time_t start = time(NULL);
    struct sockaddr_in addr;

#ifdef HAVE_GNUTLS_GNUTLS_H
    gnutls_session *session = NULL;
#endif
    cib_client_t *new_client = NULL;

    xmlNode *login = NULL;
    const char *user = NULL;
    const char *pass = NULL;
    const char *tmp = NULL;

    cl_uuid_t client_id;
    char uuid_str[UU_UNPARSE_SIZEOF];

#ifdef HAVE_DECL_NANOSLEEP
    const struct timespec sleepfast = { 0, 10000000 };  /* 10 millisec */
#endif

    /* accept the connection */
    laddr = sizeof(addr);
    csock = accept(ssock, (struct sockaddr *)&addr, &laddr);
    crm_debug("New %s connection from %s",
              ssock == remote_tls_fd ? "secure" : "clear-text", inet_ntoa(addr.sin_addr));

    if (csock == -1) {
        crm_err("accept socket failed");
        return TRUE;
    }

    if (ssock == remote_tls_fd) {
#ifdef HAVE_GNUTLS_GNUTLS_H
        /* create gnutls session for the server socket */
        session = create_tls_session(csock, GNUTLS_SERVER);
        if (session == NULL) {
            crm_err("TLS session creation failed");
            close(csock);
            return TRUE;
        }
#endif
    }

    do {
        crm_trace("Iter: %d", lpc++);
        if (ssock == remote_tls_fd) {
#ifdef HAVE_GNUTLS_GNUTLS_H
            login = cib_recv_remote_msg(session, TRUE);
#endif
        } else {
            login = cib_recv_remote_msg(GINT_TO_POINTER(csock), FALSE);
        }
        if (login != NULL) {
            break;
        }
#ifdef HAVE_DECL_NANOSLEEP
        nanosleep(&sleepfast, NULL);
#else
        sleep(1);
#endif
        now = time(NULL);

        /* Peers have 3s to connect */
    } while (login == NULL && (start - now) < 4);

    crm_log_xml_info(login, "Login: ");
    if (login == NULL) {
        goto bail;
    }

    tmp = crm_element_name(login);
    if (safe_str_neq(tmp, "cib_command")) {
        crm_err("Wrong tag: %s", tmp);
        goto bail;
    }

    tmp = crm_element_value(login, "op");
    if (safe_str_neq(tmp, "authenticate")) {
        crm_err("Wrong operation: %s", tmp);
        goto bail;
    }

    user = crm_element_value(login, "user");
    pass = crm_element_value(login, "password");

    /* Non-root daemons can only validate the password of the
     * user they're running as
     */
    if (check_group_membership(user, CRM_DAEMON_GROUP) == FALSE) {
        crm_err("User is not a member of the required group");
        goto bail;

    } else if (authenticate_user(user, pass) == FALSE) {
        crm_err("PAM auth failed");
        goto bail;
    }

    /* send ACK */
    crm_malloc0(new_client, sizeof(cib_client_t));
    num_clients++;
    new_client->channel_name = "remote";
    new_client->name = crm_element_value_copy(login, "name");

    cl_uuid_generate(&client_id);
    cl_uuid_unparse(&client_id, uuid_str);

    CRM_CHECK(new_client->id == NULL, crm_free(new_client->id));
    new_client->id = crm_strdup(uuid_str);

#if ENABLE_ACL
    new_client->user = crm_strdup(user);
#endif

    new_client->callback_id = NULL;
    if (ssock == remote_tls_fd) {
#ifdef HAVE_GNUTLS_GNUTLS_H
        new_client->encrypted = TRUE;
        new_client->channel = (void *)session;
#endif
    } else {
        new_client->channel = GINT_TO_POINTER(csock);
    }

    free_xml(login);
    login = create_xml_node(NULL, "cib_result");
    crm_xml_add(login, F_CIB_OPERATION, CRM_OP_REGISTER);
    crm_xml_add(login, F_CIB_CLIENTID, new_client->id);
    cib_send_remote_msg(new_client->channel, login, new_client->encrypted);
    free_xml(login);

    new_client->source =
        (void *)G_main_add_fd(G_PRIORITY_DEFAULT, csock, FALSE, cib_remote_msg, new_client,
                              cib_remote_connection_destroy);

    g_hash_table_insert(client_list, new_client->id, new_client);

    return TRUE;

  bail:
    if (ssock == remote_tls_fd) {
#ifdef HAVE_GNUTLS_GNUTLS_H
        gnutls_bye(*session, GNUTLS_SHUT_RDWR);
        gnutls_deinit(*session);
        gnutls_free(session);
#endif
    }
    close(csock);
    free_xml(login);
    return TRUE;
}

void
cib_remote_connection_destroy(gpointer user_data)
{
    cib_client_t *client = user_data;

    if (client == NULL) {
        return;
    }

    crm_trace("Cleaning up after client disconnect: %s/%s/%s",
              crm_str(client->name), client->channel_name, client->id);

    if (client->id != NULL) {
        if (!g_hash_table_remove(client_list, client->id)) {
            crm_err("Client %s not found in the hashtable", client->name);
        }
    }

    if (client->source != NULL) {
        /* Should this even be necessary? */
        crm_trace("Deleting %s (%p) from mainloop", client->name, client->source);
        G_main_del_fd((GFDSource *) client->source);
        client->source = NULL;
    }

    crm_trace("Destroying %s (%p)", client->name, user_data);
    num_clients--;
    crm_trace("Num unfree'd clients: %d", num_clients);
    crm_free(client->name);
    crm_free(client->callback_id);
    crm_free(client->id);
    crm_free(client->user);
    crm_free(client);
    crm_trace("Freed the cib client");

    if (cib_shutdown_flag && g_hash_table_size(client_list) == 0) {
        crm_info("All clients disconnected...");
        initiate_exit();
    }

    return;
}

gboolean
cib_remote_msg(int csock, gpointer data)
{
    const char *value = NULL;
    xmlNode *command = NULL;
    cib_client_t *client = data;

    crm_trace("%s callback", client->encrypted ? "secure" : "clear-text");

    command = cib_recv_remote_msg(client->channel, client->encrypted);
    if (command == NULL) {
        return FALSE;
    }

    value = crm_element_name(command);
    if (safe_str_neq(value, "cib_command")) {
        crm_log_xml_trace(command, "Bad command: ");
        goto bail;
    }

    if (client->name == NULL) {
        value = crm_element_value(command, F_CLIENTNAME);
        if (value == NULL) {
            client->name = crm_strdup(client->id);
        } else {
            client->name = crm_strdup(value);
        }
    }

    if (client->callback_id == NULL) {
        value = crm_element_value(command, F_CIB_CALLBACK_TOKEN);
        if (value != NULL) {
            client->callback_id = crm_strdup(value);
            crm_trace("Callback channel for %s is %s", client->id, client->callback_id);

        } else {
            client->callback_id = crm_strdup(client->id);
        }
    }

    /* unset dangerous options */
    xml_remove_prop(command, F_ORIG);
    xml_remove_prop(command, F_CIB_HOST);
    xml_remove_prop(command, F_CIB_GLOBAL_UPDATE);

    crm_xml_add(command, F_TYPE, T_CIB);
    crm_xml_add(command, F_CIB_CLIENTID, client->id);
    crm_xml_add(command, F_CIB_CLIENTNAME, client->name);
#if ENABLE_ACL
    crm_xml_add(command, F_CIB_USER, client->user);
#endif

    if (crm_element_value(command, F_CIB_CALLID) == NULL) {
        cl_uuid_t call_id;
        char call_uuid[UU_UNPARSE_SIZEOF];

        /* fix the command */
        cl_uuid_generate(&call_id);
        cl_uuid_unparse(&call_id, call_uuid);
        crm_xml_add(command, F_CIB_CALLID, call_uuid);
    }

    if (crm_element_value(command, F_CIB_CALLOPTS) == NULL) {
        crm_xml_add_int(command, F_CIB_CALLOPTS, 0);
    }

    crm_log_xml_trace(command, "Remote command: ");
    cib_common_callback_worker(command, client, FALSE, TRUE);
  bail:
    free_xml(command);
    command = NULL;
    return TRUE;
}

#ifdef HAVE_PAM
/* 
 * Useful Examples:
 *    http://www.kernel.org/pub/linux/libs/pam/Linux-PAM-html
 *    http://developer.apple.com/samplecode/CryptNoMore/index.html
 */
static int
construct_pam_passwd(int num_msg, const struct pam_message **msg,
                     struct pam_response **response, void *data)
{
    int count = 0;
    struct pam_response *reply;
    char *string = (char *)data;

    CRM_CHECK(data, return PAM_CONV_ERR);
    CRM_CHECK(num_msg == 1, return PAM_CONV_ERR);       /* We only want to handle one message */

    reply = calloc(1, sizeof(struct pam_response));
    CRM_ASSERT(reply != NULL);

    for (count = 0; count < num_msg; ++count) {
        switch (msg[count]->msg_style) {
            case PAM_TEXT_INFO:
                crm_info("PAM: %s\n", msg[count]->msg);
                break;
            case PAM_PROMPT_ECHO_OFF:
            case PAM_PROMPT_ECHO_ON:
                reply[count].resp_retcode = 0;
                reply[count].resp = string;     /* We already made a copy */
            case PAM_ERROR_MSG:
                /* In theory we'd want to print this, but then
                 * we see the password prompt in the logs
                 */
                /* crm_err("PAM error: %s\n", msg[count]->msg); */
                break;
            default:
                crm_err("Unhandled conversation type: %d", msg[count]->msg_style);
                goto bail;
        }
    }

    *response = reply;
    reply = NULL;

    return PAM_SUCCESS;

  bail:
    for (count = 0; count < num_msg; ++count) {
        if (reply[count].resp != NULL) {
            switch (msg[count]->msg_style) {
                case PAM_PROMPT_ECHO_ON:
                case PAM_PROMPT_ECHO_OFF:
                    /* Erase the data - it contained a password */
                    while (*(reply[count].resp)) {
                        *(reply[count].resp)++ = '\0';
                    }
                    free(reply[count].resp);
                    break;
            }
            reply[count].resp = NULL;
        }
    }
    free(reply);
    reply = NULL;

    return PAM_CONV_ERR;
}
#endif

int
authenticate_user(const char *user, const char *passwd)
{
#ifndef HAVE_PAM
    gboolean pass = TRUE;
#else
    int rc = 0;
    gboolean pass = FALSE;
    const void *p_user = NULL;

    struct pam_conv p_conv;
    struct pam_handle *pam_h = NULL;
    static const char *pam_name = NULL;

    if (pam_name == NULL) {
        pam_name = getenv("CIB_pam_service");
    }
    if (pam_name == NULL) {
        pam_name = "login";
    }

    p_conv.conv = construct_pam_passwd;
    p_conv.appdata_ptr = strdup(passwd);

    rc = pam_start(pam_name, user, &p_conv, &pam_h);
    if (rc != PAM_SUCCESS) {
        crm_err("Could not initialize PAM: %s (%d)", pam_strerror(pam_h, rc), rc);
        goto bail;
    }

    rc = pam_authenticate(pam_h, 0);
    if (rc != PAM_SUCCESS) {
        crm_err("Authentication failed for %s: %s (%d)", user, pam_strerror(pam_h, rc), rc);
        goto bail;
    }

    /* Make sure we authenticated the user we wanted to authenticate.
     * Since we also run as non-root, it might be worth pre-checking
     * the user has the same EID as us, since that the only user we
     * can authenticate.
     */
    rc = pam_get_item(pam_h, PAM_USER, &p_user);
    if (rc != PAM_SUCCESS) {
        crm_err("Internal PAM error: %s (%d)", pam_strerror(pam_h, rc), rc);
        goto bail;

    } else if (p_user == NULL) {
        crm_err("Unknown user authenticated.");
        goto bail;

    } else if (safe_str_neq(p_user, user)) {
        crm_err("User mismatch: %s vs. %s.", (const char *)p_user, (const char *)user);
        goto bail;
    }

    rc = pam_acct_mgmt(pam_h, 0);
    if (rc != PAM_SUCCESS) {
        crm_err("Access denied: %s (%d)", pam_strerror(pam_h, rc), rc);
        goto bail;
    }
    pass = TRUE;

  bail:
    rc = pam_end(pam_h, rc);
#endif
    return pass;
}