/*
 *
  ***** BEGIN LICENSE BLOCK *****
 
  Copyright (C) 2009-2019 Olof Hagsand and Benny Holmgren

  This file is part of CLIXON.

  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.

  Alternatively, the contents of this file may be used under the terms of
  the GNU General Public License Version 3 or later (the "GPL"),
  in which case the provisions of the GPL are applicable instead
  of those above. If you wish to allow use of your version of this file only
  under the terms of the GPL, and not to allow others to
  use your version of this file under the terms of Apache License version 2, 
  indicate your decision by deleting the provisions above and replace them with
  the  notice and other provisions required by the GPL. If you do not delete
  the provisions above, a recipient may use your version of this file under
  the terms of any one of the Apache License version 2 or the GPL.

  ***** END LICENSE BLOCK *****

 */

#ifdef HAVE_CONFIG_H
#include "clixon_config.h" /* generated by config & autoconf */
#endif

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdarg.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include <time.h>
#include <syslog.h>
#include <grp.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/param.h>
#ifdef HAVE_SYS_UCRED_H
#include <sys/types.h>
#include <sys/ucred.h>
#endif
#define __USE_GNU
#define _GNU_SOURCE /* for ucred */
#include <sys/socket.h>
#include <sys/param.h>
#include <sys/types.h>

#include <sys/un.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <cligen/cligen.h>

/* clicon */
#include <clixon/clixon.h>

#include "backend_socket.h"
#include "backend_client.h"
#include "backend_handle.h"

static int
config_socket_init_ipv4(clicon_handle h,
			char         *dst)
{
    int                s;
    struct sockaddr_in addr;
    uint16_t           port;

    port = clicon_sock_port(h);

    /* create inet socket */
    if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
	clicon_err(OE_UNIX, errno, "socket");
	return -1;
    }
//    setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (void*)&one, sizeof(one));
    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    if (inet_pton(addr.sin_family, dst, &addr.sin_addr) != 1){
	clicon_err(OE_UNIX, errno, "inet_pton: %s (Expected IPv4 address. Check settings of CLICON_SOCK_FAMILY and CLICON_SOCK)", dst);
	goto err; /* Could check getaddrinfo */
    }
    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0){
	clicon_err(OE_UNIX, errno, "bind");
	goto err;
    }
    clicon_debug(1, "Listen on server socket at %s:%hu", dst, port);
    if (listen(s, 5) < 0){
	clicon_err(OE_UNIX, errno, "listen");
	goto err;
    }
    return s;
  err:
    close(s);
    return -1;
}

/*! Open a socket and bind it to a file descriptor
 *
 * The socket is accessed via CLICON_SOCK option, has 770 permissions
 * and group according to CLICON_SOCK_GROUP option.
 */
static int
config_socket_init_unix(clicon_handle h,
			char         *sock)
{
    int                s;
    struct sockaddr_un addr;
    mode_t             old_mask;
    char              *config_group;
    gid_t              gid;
    struct stat        st;

    if (lstat(sock, &st) == 0 && unlink(sock) < 0){
	clicon_err(OE_UNIX, errno, "unlink(%s)", sock);
	return -1;
    }
    /* then find configuration group (for clients) and find its groupid */
    if ((config_group = clicon_sock_group(h)) == NULL){
	clicon_err(OE_FATAL, 0, "clicon_sock_group option not set");
	return -1;
    }
    if (group_name2gid(config_group, &gid) < 0)
	return -1;
#if 0
    if (gid == 0) 
	clicon_log(LOG_WARNING, "%s: No such group: %s\n", __FUNCTION__, config_group);
#endif
    /* create unix socket */
    if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
	clicon_err(OE_UNIX, errno, "socket");
	return -1;
    }
//    setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (void*)&one, sizeof(one));
    memset(&addr, 0, sizeof(addr));
    addr.sun_family = AF_UNIX;
    strncpy(addr.sun_path, sock, sizeof(addr.sun_path)-1);
    old_mask = umask(S_IRWXO | S_IXGRP | S_IXUSR);
    if (bind(s, (struct sockaddr *)&addr, SUN_LEN(&addr)) < 0){
	clicon_err(OE_UNIX, errno, "bind");
	umask(old_mask); 
	goto err;
    }
    umask(old_mask); 
    /* change socket path file group */
    if (lchown(sock, -1, gid) < 0){
	clicon_err(OE_UNIX, errno, "lchown(%s, %s)", sock, config_group);
	goto err;
    }
    clicon_debug(1, "Listen on server socket at %s", addr.sun_path);
    if (listen(s, 5) < 0){
	clicon_err(OE_UNIX, errno, "listen");
	goto err;
    }
    return s;
  err:
    close(s);
    return -1;
}

int
backend_socket_init(clicon_handle h)
{
    char *sock;

    if ((sock = clicon_sock(h)) == NULL){
	clicon_err(OE_FATAL, 0, "CLICON_SOCK option not set");
	return -1;
    }
    switch (clicon_sock_family(h)){
    case AF_UNIX:
	return config_socket_init_unix(h, sock);
	break;
    case AF_INET:
	return config_socket_init_ipv4(h, sock);
	break;
    }
    return 0;
}

/*! Accept new socket client
 * XXX: credentials not properly implemented
 */
int
backend_accept_client(int   fd,
		      void *arg)
{
    int           retval = -1;
    clicon_handle h = (clicon_handle)arg;
    int           s;
    struct sockaddr_un from;
    socklen_t     len;
    struct client_entry *ce;
#ifdef DONT_WORK /* XXX HAVE_SYS_UCRED_H */
    struct xucred credentials; 	/* FreeBSD. */
    socklen_t     clen;
#elif defined(SO_PEERCRED)
    struct ucred credentials; 	/* Linux. */
    socklen_t     clen;
#endif
    char         *config_group;
    struct group *gr;
    char         *mem;
    int           i;

    clicon_debug(2, "%s", __FUNCTION__);
    len = sizeof(from);
    if ((s = accept(fd, (struct sockaddr*)&from, &len)) < 0){
	clicon_err(OE_UNIX, errno, "accept");
	goto done;
    }
#if defined(SO_PEERCRED)
    /* fill in the user data structure */
    clen =  sizeof(credentials);
    if(getsockopt(s, SOL_SOCKET, SO_PEERCRED/* XXX finns ej i freebsd*/, &credentials, &clen)){
	clicon_err(OE_UNIX, errno, "getsockopt");
	goto done;
    }
#endif   
    if ((ce = backend_client_add(h, (struct sockaddr*)&from)) == NULL)
	goto done;
#if defined(SO_PEERCRED)
    ce->ce_pid = credentials.pid;
    ce->ce_uid = credentials.uid;
#endif
    ce->ce_handle = h;

    /* check credentials of caller (not properly implemented yet) */
    if ((config_group = clicon_sock_group(h)) == NULL){
	clicon_err(OE_FATAL, 0, "clicon_sock_group option not set");
	goto done;
    }
    if ((gr = getgrnam(config_group)) != NULL){
	i = 0; /* one of mem should correspond to ce->ce_uid */
	while ((mem = gr->gr_mem[i++]) != NULL)
	    ;
    }

#if 0
    { /* XXX */
	int ii;
	struct client_entry *c;
	for (c = ce_list, ii=0; c; c = c->ce_next, ii++);
	clicon_debug(1, "Open client socket (nr:%d pid:%d [Total: %d])",
		ce->ce_nr, ce->ce_pid, ii);
    }
#endif
    ce->ce_s = s;

    /*
     * Here we register callbacks for actual data socket 
     */
    if (event_reg_fd(s, from_client, (void*)ce, "local netconf client socket") < 0)
	goto done;
    retval = 0;
 done:
    return retval;
}