/*
 * packet-lua.c
 *
 * Wireshark's interface to the Lua Programming Language
 *
 * (c) 2006, Luis E. Garcia Ontanon <luis@ontanon.org>
 *
 * $Id: init_wslua.c 27002 2008-12-15 15:46:53Z rbalint $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * 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 program 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 program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include "wslua.h"
#include <epan/nstime.h>
#include <math.h>
#include <epan/expert.h>
#include <epan/ex-opt.h>
#include <wsutil/privileges.h>
#include <wsutil/file_util.h>

static lua_State* L = NULL;

packet_info* lua_pinfo;
struct _wslua_treeitem* lua_tree;
tvbuff_t* lua_tvb;
int lua_malformed;
int lua_dissectors_table_ref;

dissector_handle_t lua_data_handle;


static int wslua_not_register_menu(lua_State* LS) {
    luaL_error(LS,"too late to register a menu");
    return 0;
}

int dissect_lua(tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree) {
    int consumed_bytes = tvb->length;
    lua_pinfo = pinfo;
    lua_tvb = tvb;

    lua_tree = g_malloc(sizeof(struct _wslua_treeitem));
    lua_tree->tree = tree;
    lua_tree->item = proto_tree_add_text(tree,tvb,0,0,"lua fake item");
    lua_tree->expired = FALSE;
    PROTO_ITEM_SET_HIDDEN(lua_tree->item);

    /*
     * almost equivalent to Lua:
     * dissectors[current_proto](tvb,pinfo,tree)
     */

    lua_settop(L,0);

    lua_rawgeti(L, LUA_REGISTRYINDEX, lua_dissectors_table_ref);

    lua_pushstring(L, pinfo->current_proto);
    lua_gettable(L, -2);

    lua_remove(L,1);


    if (lua_isfunction(L,1)) {

        push_Tvb(L,tvb);
        push_Pinfo(L,pinfo);
        push_TreeItem(L,lua_tree);

        if  ( lua_pcall(L,3,1,0) ) {
            const gchar* error = lua_tostring(L,-1);

            proto_item* pi = proto_tree_add_text(tree,tvb,0,0,"Lua Error: %s",error);
            expert_add_info_format(pinfo, pi, PI_DEBUG, PI_ERROR ,"Lua Error");
        } else {

            /* if the Lua dissector reported the consumed bytes, pass it to our caller */
            if (lua_isnumber(L, -1)) { 
                /* we got the consumed bytes or the missing bytes as a negative number */
                consumed_bytes = (int) lua_tonumber(L, -1);
                lua_pop(L, 1);
            }
        }

    } else {
        proto_item* pi = proto_tree_add_text(tree,tvb,0,0,"Lua Error: did not find the %s dissector"
                                             " in the dissectors table",pinfo->current_proto);

        expert_add_info_format(pinfo, pi, PI_DEBUG, PI_ERROR ,"Lua Error");
    }

    clear_outstanding_Tvb();
    clear_outstanding_Pinfo();
    clear_outstanding_Column();
    clear_outstanding_Columns();
    clear_outstanding_TreeItem();


    lua_pinfo = NULL;
    lua_tree = NULL;
    lua_tvb = NULL;

    return consumed_bytes;

}

static void iter_table_and_call(lua_State* LS, int env, const gchar* table_name, lua_CFunction error_handler) {
    lua_settop(LS,0);

    lua_pushcfunction(LS,error_handler);
    lua_pushstring(LS, table_name);
    lua_gettable(LS, env);

    if (!lua_istable(LS, 2)) {
        report_failure("Lua: either `%s' does not exist or it is not a table!\n",table_name);
        lua_close(LS);
        L = NULL;
        return;
    }

    lua_pushnil(LS);

    while (lua_next(LS, 2)) {
        const gchar* name = lua_tostring(L,-2);

        if (lua_isfunction(LS,-1)) {

            if ( lua_pcall(LS,0,0,1) ) {
                    lua_pop(LS,1);
            }

        } else {
            report_failure("Lua: Something not a function got its way into the %s.%s",table_name,name);
            lua_close(LS);
            L = NULL;
            return;
        }
    }

    lua_settop(LS,0);
}


static int init_error_handler(lua_State* LS) {
    const gchar* error =  lua_tostring(LS,1);
    report_failure("Lua: Error During execution of Initialization:\n %s",error);
    return 0;
}


static void wslua_init_routine(void) {
    static gboolean initialized = FALSE;

    if ( ! initialized ) {
        lua_prime_all_fields(NULL);
        initialized = TRUE;
    }

    if (L) {
        iter_table_and_call(L, LUA_GLOBALSINDEX, WSLUA_INIT_ROUTINES,init_error_handler);
    }

}


static const char *getF(lua_State *L _U_, void *ud, size_t *size)
{
    FILE *f=(FILE *)ud;
    static char buff[512];
    if (feof(f)) return NULL;
    *size=fread(buff,1,sizeof(buff),f);
    return (*size>0) ? buff : NULL;
}

static int lua_main_error_handler(lua_State* LS) {
    const gchar* error =  lua_tostring(LS,1);
    report_failure("Lua: Error during loading:\n %s",error);
    return 0;
}

void lua_load_script(const gchar* filename) {
    FILE* file;

    if (! ( file = ws_fopen(filename,"r")) ) {
        report_open_failure(filename,errno,FALSE);
        return;
    }

    lua_settop(L,0);

    lua_pushcfunction(L,lua_main_error_handler);

    switch (lua_load(L,getF,file,filename)) {
        case 0:
            lua_pcall(L,0,0,1);
            fclose(file);
            return;
        case LUA_ERRSYNTAX: {
            report_failure("Lua: syntax error during precompilation of `%s':\n%s",filename,lua_tostring(L,-1));
            fclose(file);
            return;
        }
        case LUA_ERRMEM:
            report_failure("Lua: memory allocation error during execution of %s",filename);
            fclose(file);
            return;
    }

}

static void basic_logger(const gchar *log_domain _U_,
                          GLogLevelFlags log_level _U_,
                          const gchar *message,
                          gpointer user_data _U_) {
    fputs(message,stderr);
}

static int wslua_panic(lua_State* LS) {
    g_error("LUA PANIC: %s",lua_tostring(LS,-1));
    return 0;
}

int wslua_init(lua_State* LS) {
    gchar* filename;
    const funnel_ops_t* ops = funnel_get_funnel_ops();
    gboolean run_anyway = FALSE;

    /* set up the logger */
    g_log_set_handler(LOG_DOMAIN_LUA, G_LOG_LEVEL_CRITICAL|
                      G_LOG_LEVEL_WARNING|
                      G_LOG_LEVEL_MESSAGE|
                      G_LOG_LEVEL_INFO|
                      G_LOG_LEVEL_DEBUG,
                      ops ? ops->logger : basic_logger, NULL);

    if (!L) {
        if (LS)
            L = LS;
        else
            L = luaL_newstate();
    }

    WSLUA_INIT(L);

    lua_atpanic(L,wslua_panic);

    /* the init_routines table (accessible by the user) */
    lua_pushstring(L, WSLUA_INIT_ROUTINES);
    lua_newtable (L);
    lua_settable(L, LUA_GLOBALSINDEX);

    /* the dissectors table goes in the registry (not accessible) */
    lua_newtable (L);
    lua_dissectors_table_ref = luaL_ref(L, LUA_REGISTRYINDEX);

    /* set running_superuser variable to it's propper value */
    WSLUA_REG_GLOBAL_BOOL(L,"running_superuser",started_with_special_privs());
    
    /* special constant used by PDU reassembly handling */
    /* see dissect_lua() for notes */
    WSLUA_REG_GLOBAL_NUMBER(L,"DESEGMENT_ONE_MORE_SEGMENT",DESEGMENT_ONE_MORE_SEGMENT);

    /* load system's init.lua */
    filename = get_datafile_path("init.lua");

    if (( file_exists(filename))) {
        lua_load_script(filename);
    }

    g_free(filename);
    filename = NULL;

    /* check if lua is to be disabled */
    lua_pushstring(L,"disable_lua");
    lua_gettable(L, LUA_GLOBALSINDEX);

    if (lua_isboolean(L,-1) && lua_toboolean(L,-1)) {
        /* disable lua */
        lua_close(L);
        L = NULL;
        return 0;
    }

    /* check whether we should run other scripts even if running superuser */
    lua_pushstring(L,"run_user_scripts_when_superuser");
    lua_gettable(L, LUA_GLOBALSINDEX);

    if (lua_isboolean(L,-1) && lua_toboolean(L,-1)) {
        run_anyway = TRUE;
    }


    /* if we are indeed superuser run user scripts only if told to do so */
    if ( (!started_with_special_privs()) || run_anyway ) {
        filename = get_persconffile_path("init.lua", FALSE, FALSE);

        if (( file_exists(filename))) {
            lua_load_script(filename);
            g_free(filename);
            filename = NULL;
        }

        while((filename = (gchar *)ex_opt_get_next("lua_script"))) {
            lua_load_script(filename);
        }
    }

    /* at this point we're set up so register the init routine */
    register_init_routine(wslua_init_routine);

    /*
     * after this point it is too late to register a menu
     * disable the function to avoid weirdness
     */
    lua_pushstring(L, "register_menu");
    lua_pushcfunction(L, wslua_not_register_menu);
    lua_settable(L, LUA_GLOBALSINDEX);

    /* set up some essential globals */
    lua_pinfo = NULL;
    lua_tree = NULL;
    lua_tvb = NULL;

    lua_data_handle = find_dissector("data");
    lua_malformed = proto_get_id_by_filter_name("malformed");

    Proto_commit(L);

    return 0;
}

lua_State* wslua_state() { return L; }