/*
 *
  ***** 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 <sys/time.h>
#include <sys/socket.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <pwd.h>
#include <netinet/in.h>
#include <libgen.h>

/* cligen */
#include <cligen/cligen.h>

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

#include "clixon_netconf.h"
#include "netconf_lib.h"
#include "netconf_hello.h"
#include "netconf_rpc.h"

/* Command line options to be passed to getopt(3) */
#define NETCONF_OPTS "hD:f:l:qa:u:d:p:y:U:t:eo:"

#define NETCONF_LOGFILE "/tmp/clixon_netconf.log"

/*! Ignore errors on packet errors: continue */
static int ignore_packet_errors = 1;

/*! Process incoming packet 
 * @param[in]   h    Clicon handle
 * @param[in]   cb   Packet buffer
 */
static int
netconf_input_packet(clicon_handle h, 
		     cbuf         *cb)
{
    int        retval = -1;
    char      *str;
    char      *str0;
    cxobj     *xreq = NULL; /* Request (in) */
    int        isrpc = 0;   /* either hello or rpc */
    cbuf      *cbret = NULL;
    cxobj     *xret = NULL; /* Return (out) */
    cxobj     *xrpc;
    cxobj     *xc;
    yang_stmt *yspec;
    int        ret;
    cxobj     *xa;
    cxobj     *xa2;

    clicon_debug(1, "%s", __FUNCTION__);
    clicon_debug(2, "%s: \"%s\"", __FUNCTION__, cbuf_get(cb));
    if ((cbret = cbuf_new()) == NULL){
	clicon_err(LOG_ERR, errno, "cbuf_new");
	goto done;
    }
    yspec = clicon_dbspec_yang(h);
    if ((str0 = strdup(cbuf_get(cb))) == NULL){
	clicon_log(LOG_ERR, "%s: strdup: %s", __FUNCTION__, strerror(errno));
	return -1;
    }
    str = str0;
    /* Parse incoming XML message */
    if (xml_parse_string(str, yspec, &xreq) < 0){ 
	free(str0);
	if (netconf_operation_failed(cbret, "rpc", clicon_err_reason)< 0)
	    goto done;
	netconf_output_encap(1, cbret, "rpc-error");
	goto done;
    }
    free(str0);
    if ((xrpc=xpath_first(xreq, "//rpc")) != NULL){
        isrpc++;
	if (xml_spec_populate_rpc(h, xrpc, yspec) < 0)
	    goto done;
	if ((ret = xml_yang_validate_rpc(h, xrpc, &xret)) < 0) 
	    goto done;
	if (ret == 0){
	    clicon_xml2cbuf(cbret, xret, 0, 0, -1);
	    netconf_output_encap(1, cbret, "rpc-error");
	    goto ok;
	}
    }
    else
        if (xpath_first(xreq, "//hello") != NULL)
	    ;
        else{
            clicon_log(LOG_WARNING, "Invalid netconf msg: neither rpc or hello: dropped");
            goto done;
        }
    if (!isrpc){ /* hello */
	if (netconf_hello_dispatch(xreq) < 0)
	    goto done;
    }
    else  /* rpc */
	if (netconf_rpc_dispatch(h, xrpc, &xret) < 0){
	    goto done;
	}
	else{ /* there is a return message in xret */

	    if (xret == NULL){
		if (netconf_operation_failed(cbret, "rpc", "Internal error: no xml return")< 0)
		    goto done;
		netconf_output_encap(1, cbret, "rpc-error");
		goto done;
	    }
	    if ((xc = xml_child_i(xret, 0))!=NULL){
		xa=NULL;
		/* Copy message-id attribute from incoming to reply. 
		 * RFC 6241:
		 * If additional attributes are present in an <rpc> element, a NETCONF
		 * peer MUST return them unmodified in the <rpc-reply> element.  This
		 * includes any "xmlns" attributes.
		 */
		while ((xa = xml_child_each(xrpc, xa, CX_ATTR)) != NULL){
		    if ((xa2 = xml_dup(xa)) ==NULL)
			goto done;
		    if (xml_addsub(xc, xa2) < 0)
			goto done;
		}
		clicon_xml2cbuf(cbret, xml_child_i(xret,0), 0, 0, -1);
		if (netconf_output_encap(1, cbret, "rpc-reply") < 0){
		    cbuf_free(cbret);
		    goto done;
		}
	    }
	}
 ok:
    retval = 0;
  done:
    if (xreq)
	xml_free(xreq);
    if (xret)
	xml_free(xret);
    if (cbret)
	cbuf_free(cbret);
    return retval;
}

/*! Get netconf message: detect end-of-msg 
 * @param[in]   s    Socket where input arrived. read from this.
 * @param[in]   arg  Clicon handle.
 * This routine continuously reads until no more data on s. There could
 * be risk of starvation, but the netconf client does little else than
 * read data so I do not see a danger of true starvation here.
 */
static int
netconf_input_cb(int   s, 
		 void *arg)
{
    int           retval = -1;
    clicon_handle h = arg;
    unsigned char buf[BUFSIZ];
    int           i;
    int           len;
    cbuf         *cb=NULL;
    int           xml_state = 0;
    int           poll;

    if ((cb = cbuf_new()) == NULL){
	clicon_err(OE_XML, errno, "cbuf_new");
	return retval;
    }
    memset(buf, 0, sizeof(buf));
    while (1){
	if ((len = read(s, buf, sizeof(buf))) < 0){
	    if (errno == ECONNRESET)
		len = 0; /* emulate EOF */
	    else{
		clicon_log(LOG_ERR, "%s: read: %s", __FUNCTION__, strerror(errno));
		goto done;
	    }
	} /* read */
	if (len == 0){ 	/* EOF */
	    cc_closed++;
	    close(s);
	    retval = 0;
	    goto done;
	}
	for (i=0; i<len; i++){
	    if (buf[i] == 0)
		continue; /* Skip NULL chars (eg from terminals) */
	    cprintf(cb, "%c", buf[i]);
	    if (detect_endtag("]]>]]>",
			      buf[i],
			      &xml_state)) {
		/* OK, we have an xml string from a client */
		/* Remove trailer */
		*(((char*)cbuf_get(cb)) + cbuf_len(cb) - strlen("]]>]]>")) = '\0';
		if (netconf_input_packet(h, cb) < 0 &&
		    !ignore_packet_errors) // default is to ignore errors
		    goto done; 
		if (cc_closed)
		    break;
		cbuf_reset(cb);
	    }
	}
	/* poll==1 if more, poll==0 if none */
	if ((poll = event_poll(s)) < 0)
	    goto done;
	if (poll == 0)
	    break; /* No data to read */
    } /* while */
    retval = 0;
  done:
    if (cb)
	cbuf_free(cb);
    if (cc_closed) 
	retval = -1;
    return retval;
}

/*! Send netconf hello message
 * @param[in]   h   Clicon handle
 * @param[in]   s   File descriptor to write on (eg 1 - stdout)
 */
static int
send_hello(clicon_handle h,
	   int           s)
{
    int   retval = -1;
    cbuf *cb;
    
    if ((cb = cbuf_new()) == NULL){
	clicon_log(LOG_ERR, "%s: cbuf_new", __FUNCTION__);
	goto done;
    }
    if (netconf_create_hello(h, cb, getpid()) < 0)
	goto done;
    if (netconf_output(s, cb, "hello") < 0)
	goto done;
    retval = 0;
  done:
    if (cb)
	cbuf_free(cb);
    return retval;
}

/*! Clean and close all state of netconf process (but dont exit). 
 * Cannot use h after this 
 * @param[in]  h  Clixon handle
 */
static int
netconf_terminate(clicon_handle h)
{
    yang_stmt  *yspec;
    cxobj      *x;
    
    clixon_plugin_exit(h);
    rpc_callback_delete_all(h);
    clicon_rpc_close_session(h);
    if ((yspec = clicon_dbspec_yang(h)) != NULL)
	yspec_free(yspec);
    if ((yspec = clicon_config_yang(h)) != NULL)
	yspec_free(yspec);
    if ((x = clicon_conf_xml(h)) != NULL)
	xml_free(x);
    event_exit();
    clicon_handle_exit(h);
    clicon_log_exit();
    return 0;
}

static int
timeout_fn(int s,
	   void *arg)
{
    clicon_err(OE_EVENTS, ETIMEDOUT, "User request timeout");
    return -1; 
}

/*! Usage help routine
 * @param[in]  h      Clicon handle
 * @param[in]  argv0  command line
 */
static void
usage(clicon_handle h,
      char         *argv0)
{
    fprintf(stderr, "usage:%s\n"
	    "where options are\n"
            "\t-h\t\tHelp\n"
	    "\t-D <level>\tDebug level\n"
    	    "\t-f <file>\tConfiguration file (mandatory)\n"
	    "\t-l (e|o|s|f<file>) \tLog on std(e)rr, std(o)ut, (s)yslog, (f)ile (syslog is default)\n"
            "\t-q\t\tQuiet: dont send hello prompt\n"
    	    "\t-a UNIX|IPv4|IPv6\tInternal backend socket family\n"
    	    "\t-u <path|addr>\tInternal socket domain path or IP addr (see -a)\n"
	    "\t-d <dir>\tSpecify netconf plugin directory dir (default: %s)\n"
	    "\t-p <dir>\tYang directory path (see CLICON_YANG_DIR)\n"
	    "\t-y <file>\tLoad yang spec file (override yang main module)\n"
	    "\t-U <user>\tOver-ride unix user with a pseudo user for NACM.\n"
	    "\t-t <sec>\tTimeout in seconds. Quit after this time.\n"
	    "\t-e \tDont ignore errors on packet input.\n"
	    "\t-o \"<option>=<value>\"\tGive configuration option overriding config file (see clixon-config.yang)\n",
	    argv0,
	    clicon_netconf_dir(h)
	    );
    exit(0);
}

int
main(int    argc,
     char **argv)
{
    int              retval = -1;
    int              c;
    char            *argv0 = argv[0];
    int              quiet = 0;
    clicon_handle    h;
    char            *dir;
    int              logdst = CLICON_LOG_STDERR;
    struct passwd   *pw;
    struct timeval   tv = {0,}; /* timeout */
    yang_stmt       *yspec = NULL;
    yang_stmt       *yspecfg = NULL; /* For config XXX clixon bug */
    char            *str;
    
    /* Create handle */
    if ((h = clicon_handle_init()) == NULL)
	return -1;
    /* In the startup, logs to stderr & debug flag set later */
    clicon_log_init(__PROGRAM__, LOG_INFO, logdst); 

    /* Set username to clicon handle. Use in all communication to backend */
    if ((pw = getpwuid(getuid())) == NULL){
	clicon_err(OE_UNIX, errno, "getpwuid");
	goto done;
    }
    if (clicon_username_set(h, pw->pw_name) < 0)
	goto done;
    while ((c = getopt(argc, argv, NETCONF_OPTS)) != -1)
	switch (c) {
	case 'h' : /* help */
	    usage(h, argv[0]);
	    break;
	case 'D' : /* debug */
	    if (sscanf(optarg, "%d", &debug) != 1)
		usage(h, argv[0]);
	    break;
	 case 'f': /* override config file */
	    if (!strlen(optarg))
		usage(h, argv[0]);
	    clicon_option_str_set(h, "CLICON_CONFIGFILE", optarg);
	    break;
	 case 'l': /* Log destination: s|e|o */
	    if ((logdst = clicon_log_opt(optarg[0])) < 0)
		usage(h, argv[0]);
	    if (logdst == CLICON_LOG_FILE &&
		strlen(optarg)>1 &&
		clicon_log_file(optarg+1) < 0)
		goto done;
	     break;
	}

    /* 
     * Logs, error and debug to stderr or syslog, set debug level
     */
    clicon_log_init(__PROGRAM__, debug?LOG_DEBUG:LOG_INFO, logdst); 
    clicon_debug_init(debug, NULL); 

    /* Create configure yang-spec */
    if ((yspecfg = yspec_new()) == NULL)
	goto done;
    /* Find and read configfile */
    if (clicon_options_main(h, yspecfg) < 0)
	return -1;
    clicon_config_yang_set(h, yspecfg);
    /* Now rest of options */
    optind = 1;
    opterr = 0;
    while ((c = getopt(argc, argv, NETCONF_OPTS)) != -1)
	switch (c) {
	case 'h' : /* help */
	case 'D' : /* debug */
	case 'f':  /* config file */
	case 'l':  /* log  */
	    break; /* see above */
	case 'q':  /* quiet: dont write hello */
	    quiet++;
	    break;
	case 'a': /* internal backend socket address family */
	    clicon_option_str_set(h, "CLICON_SOCK_FAMILY", optarg);
	    break;
	case 'u': /* internal backend socket unix domain path or ip host */
	    if (!strlen(optarg))
		usage(h, argv[0]);
	    clicon_option_str_set(h, "CLICON_SOCK", optarg);
	    break;
	case 'd':  /* Plugin directory */
	    if (!strlen(optarg))
		usage(h, argv[0]);
	    if (clicon_option_add(h, "CLICON_NETCONF_DIR", optarg) < 0)
		goto done;
	    break;
	case 'p' : /* yang dir path */
	    if (clicon_option_add(h, "CLICON_YANG_DIR", optarg) < 0)
		goto done;
	    break;
	case 'y' : /* Load yang spec file (override yang main module) */
	    if (clicon_option_add(h, "CLICON_YANG_MAIN_FILE", optarg) < 0)
		goto done;
	    break;
	case 'U': /* Clixon 'pseudo' user */
	    if (!strlen(optarg))
		usage(h, argv[0]);
	    if (clicon_username_set(h, optarg) < 0)
		goto done;
	    break;
	case 't': /* timeout in seconds */
	    tv.tv_sec = atoi(optarg);
	    break;
	case 'e': /* dont ignore packet errors */
	    ignore_packet_errors = 0;
	    break;
	case 'o':{ /* Configuration option */
	    char          *val;
	    if ((val = index(optarg, '=')) == NULL)
		usage(h, argv0);
	    *val++ = '\0';
	    if (clicon_option_add(h, optarg, val) < 0)
		goto done;
	    break;
	}
	default:
	    usage(h, argv[0]);
	    break;
	}
    argc -= optind;
    argv += optind;

    /* Access the remaining argv/argc options (after --) w clicon-argv_get() */
    clicon_argv_set(h, argv0, argc, argv);

    /* Add (hardcoded) netconf features in case ietf-netconf loaded here
     * Otherwise it is loaded in netconf_module_load below
     */
    if (netconf_module_features(h) < 0)
	goto done;

    /* Create top-level yang spec and store as option */
    if ((yspec = yspec_new()) == NULL)
	goto done;
    clicon_dbspec_yang_set(h, yspec);	

    /* Load netconf plugins before yangs are loaded (eg extension callbacks) */
    if ((dir = clicon_netconf_dir(h)) != NULL &&
	clixon_plugins_load(h, CLIXON_PLUGIN_INIT, dir, NULL) < 0)
	goto done;
    
    /* Load Yang modules
     * 1. Load a yang module as a specific absolute filename */
    if ((str = clicon_yang_main_file(h)) != NULL){
	if (yang_spec_parse_file(h, str, yspec) < 0)
	    goto done;
    }
    /* 2. Load a (single) main module */
    if ((str = clicon_yang_module_main(h)) != NULL){
	if (yang_spec_parse_module(h, str, clicon_yang_module_revision(h),
				   yspec) < 0)
	    goto done;
    }
    /* 3. Load all modules in a directory */
    if ((str = clicon_yang_main_dir(h)) != NULL){
	if (yang_spec_load_dir(h, str, yspec) < 0)
	    goto done;
    }
    /* Load clixon lib yang module */
    if (yang_spec_parse_module(h, "clixon-lib", NULL, yspec) < 0)
	goto done;
     /* Load yang module library, RFC7895 */
    if (yang_modules_init(h) < 0)
	goto done;
    /* Add netconf yang spec, used by netconf client and as internal protocol */
    if (netconf_module_load(h) < 0)
	goto done;
    /* Call start function is all plugins before we go interactive */
    if (clixon_plugin_start(h) < 0)
	goto done;
    if (!quiet)
	send_hello(h, 1);
    if (event_reg_fd(0, netconf_input_cb, h, "netconf socket") < 0)
	goto done;
    if (debug)
	clicon_option_dump(h, debug);
    if (tv.tv_sec || tv.tv_usec){
	struct timeval t;
	gettimeofday(&t, NULL);
	timeradd(&t, &tv, &t);
	if (event_reg_timeout(t, timeout_fn, NULL, "timeout") < 0)
	    goto done;
    }
    if (event_loop() < 0)
	goto done;
    retval = 0;
  done:
    if (ignore_packet_errors)
	retval = 0;
    netconf_terminate(h);
    clicon_log_init(__PROGRAM__, LOG_INFO, 0); /* Log on syslog no stderr */
    clicon_log(LOG_NOTICE, "%s: %u Terminated", __PROGRAM__, getpid());
    return retval;
}