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Improve some documentation in nse_init.cc, because it took me a really long

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time to understand some functions.
This commit is contained in:
david
2008-09-15 05:16:01 +00:00
parent baeb3093a7
commit 3cf57e7009
1 changed files with 118 additions and 48 deletions
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166
nse_init.cc
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@@ -26,6 +26,30 @@ extern NmapOps o;
extern int current_hosts;
extern int errfunc;
void stack_dump(lua_State *L) {
int i;
int top = lua_gettop(L);
for (i = 1; i <= top; i++) {
int t = lua_type(L, i);
switch (t) {
case LUA_TSTRING:
printf("\"%s\"", lua_tostring(L, i));
break;
case LUA_TBOOLEAN:
printf("%s", lua_toboolean(L, i) ? "true" : "false");
break;
case LUA_TNUMBER:
printf("%g", lua_tonumber(L, i));
break;
default:
printf("<%s>", lua_typename(L, t));
break;
}
printf(" ");
}
printf("\n");
}
/* int error_function (lua_State *L)
*
* Arguments:
@@ -424,11 +448,14 @@ typedef struct extensional_category {
/* int pick_default_categories (lua_State *L)
*
* The function is passed all the scripts/directories/categories passed
* through --scripts argument. For each of these, we check if a reserved
* category (currently "version") has been chosen, and raise a fatal error
* if so. Finally the reserved categories are added. Basically, explicitly
* adding the reserved categories is illegal.
* This function takes as arguments all the scripts/categories/directories
* passed to the --script command line option, and augments them with any other
* categories that should be added. These are "default" if script scanning was
* requested and no scripts were given on the command line, and "version" if
* version scanning was requested.
*
* If a "reserved" category (currently only "version") was listed on the command
* line, give a fatal error.
*/
static int pick_default_categories (lua_State *L)
{
@@ -474,13 +501,27 @@ static int pick_default_categories (lua_State *L)
/* int entry (lua_State *L)
*
* This function is called from the script.db file. It has two upvalues:
* [1] Categories The categories/files/directories passed via --script.
* [2] Files The Files currently loaded (initially an empty table).
* A table is passed from the script database with a category and filename.
* The function tests if either the script's (filename's) category was chosen
* by checking [1]. Or, it loads the file if [1] has the 'category' "all" and
* the script's category is not "version".
* This function is called for each line of script.db, and is responsible for
* loading the scripts that are in requested categories.
*
* script.db is executable Lua code that makes calls to this function, with
* lines like
*
* Entry{ category = "default", filename = "script.nse" }
*
* The function has two upvalues, which are used to accumulate results while the
* database is executed:
* Categories A table of categories/scripts/directories requested, all
* initially mapping to false, plus canonicalization mappings
* (see loadcategories).
* Files A table of filenames loaded so far (initially empty).
*
* This function receives a table with a category and a filename. A filename is
* loaded if
* 1. its category is in the list of requested categories/scripts/directories,
* or
* 2. the category "all" was requested and the category of the script is not
* "version".
*/
static int entry (lua_State *L)
{
@@ -494,45 +535,58 @@ static int entry (lua_State *L)
if (!(lua_isstring(L, 2) && lua_isstring(L, 3)))
luaL_error(L, "bad entry in script database");
lua_pushvalue(L, 3); // filename
lua_gettable(L, lua_upvalueindex(2)); // already loaded?
/* Is this file already loaded? */
lua_gettable(L, lua_upvalueindex(2));
if (!lua_isnil(L, -1))
return 0;
lua_pushvalue(L, 2); // category
lua_gettable(L, lua_upvalueindex(1)); // check 1
lua_pushliteral(L, "version"); // check 2
lua_getfield(L, lua_upvalueindex(1), "all"); // check 3
// if category chosen OR category != "version" and [1].all exists
/* Push values that are used to decide whether to load this file. */
lua_pushvalue(L, 2); // Category name.
lua_gettable(L, lua_upvalueindex(1)); // If non-nil: a requested category.
lua_pushliteral(L, "version"); // For literal comparison against the "version" category.
lua_getfield(L, lua_upvalueindex(1), "all"); // If non-nil: "all" was requested.
// If category chosen OR ("all" chosen AND category != "version")
if ((not_all = (!lua_isnil(L, -3))) ||
(!(lua_isnil(L, -1) || lua_equal(L, 2, -2))))
{
/* Mark this category as used. */
if (not_all)
lua_pushvalue(L, 2);
else
lua_pushliteral(L, "all");
lua_pushvalue(L, -1);
lua_gettable(L, lua_upvalueindex(1));
/* Is this a canonicalization entry pointing to the real key? (See
* loadcategories.) */
if (!lua_isboolean(L, -1)) // points to real key?
{
/* If yes, point the real key to true. */
lua_pushvalue(L, -1);
lua_pushboolean(L, true);
lua_settable(L, lua_upvalueindex(1));
}
else
{
/* If no, just point the category name to true. */
lua_pushvalue(L, -2);
lua_pushboolean(L, true); // set category to true
lua_pushboolean(L, true);
lua_settable(L, lua_upvalueindex(1));
}
lua_pop(L, 1); // pop value
lua_pop(L, 1); // Pop Boolean.
/* Load the file and insert its name into the second upvalue, the table of
* loaded filenames. The value is true. */
if (nse_fetchfile(script_path, sizeof(script_path),
lua_tostring(L, 3)) != 1)
luaL_error(L, "%s is not a file!", lua_tostring(L, 3));
lua_pushvalue(L, 3); // filename
lua_pushboolean(L, true);
lua_settable(L, lua_upvalueindex(2)); // loaded
/* Finally, load the file (load its portrule or hostrule). */
lua_pushcclosure(L, loadfile, 0);
lua_pushstring(L, script_path);
lua_call(L, 1, 0);
@@ -542,62 +596,78 @@ static int entry (lua_State *L)
/* int loadcategories (lua_State *L)
*
* This function takes all the categories/scripts/directories
* passed to it and puts them in a table.
* This table along with an empty one are used as upvalues to the
* Entry closure (see entry above). Finally, the ./scripts/script.db
* file is loaded and it's environment set to only include the Entry
* closure. The entry function will do the work to load all script files with
* chosen categories. After the script database is executed. Any remainining
* fields (files/directories and possibly unused categories) are left in the
* table to be handled later.
*/
* This function takes all the categories/scripts/directories passed to it,
* loads the script files belonging to any of the arguments that are categories,
* and returns what's left over (script filenames, directory names, or possibly
* unused category names) in a table. The unused names all map to false. */
static int loadcategories (lua_State *L)
{
int i, top = lua_gettop(L);
char c_dbpath[MAX_FILENAME_LEN];
static const char *dbpath = SCRIPT_ENGINE_LUA_DIR SCRIPT_ENGINE_DATABASE;
/* Build the script database if it doesn't exist. */
if (nmap_fetchfile(c_dbpath, sizeof(c_dbpath), dbpath) == 0)
{
lua_pushcclosure(L, init_updatedb, 0);
lua_call(L, 0, 0);
}
/* Create a table that is used to keep track of which categories/scripts/
* directories are used and unused. (Because this function deals only with
* categories, script filenames and directory names always come out unused.)
* We build a table with every script/category/directory mapped to false.
* Additionally we map a lower-case version of every string to the original
* string (this is to canonicalize category names). Logic in the entry
* function checks for this canonicalization step.
*
* The entry function adjusts the values in the table to true as files are
* loaded. Later, all the keys that map to true are removed, leaving only the
* unused scripts/categories/directories. Because all strings are considered
* true, the canonicalization entries will be considered "used" and
* removed as well. */
lua_createtable(L, 0, top); // categories table
for (i = 1; i <= top; i++)
{
/* Create the canonicalization entry mapping the lower-case string to the
* original string. Do this first in case the string maps to itself (i.e.,
* it was lower-case to begin with). In that case the mapping to false will
* replace this mapping, and no canonicalization is needed. */
lua_getglobal(L, "string");
lua_getfield(L, -1, "lower"); lua_replace(L, -2);
lua_pushvalue(L, i); // Category/script/directory.
lua_call(L, 1, 1); // Canonicalize it.
lua_pushvalue(L, i);
lua_call(L, 1, 1);
lua_pushvalue(L, i);
lua_settable(L, -3); // This is a "complicated" but elegant way to tell
// if the "lowered" string category is used. Entry
// will set the "real" category (e.g. "ALL") to
// true properly. These lowered copies will also
// be removed below (because strings are true in Lua).
// If the category is already lowercase, the below
// code will replace it.
lua_pushvalue(L, i); // category/files/directory
lua_pushboolean(L, false); // false (not used)
lua_settable(L, -3);
/* Now map the name to false, meaning we assume the category/script/
* directory is unused until the entry function marks it as used. */
lua_pushvalue(L, i); // Category/script/directory.
lua_pushboolean(L, false);
lua_settable(L, -3);
}
/* Execute script.db with the Entry closure as the only thing in its
* environment (see the entry function). Entry has two upvalues: the
* used/unused table just created, and a table of loaded filenames (initially
* empty). Entry will mark categories/scripts/directories as used in the first
* table and add loaded filenames to the second table. */
luaL_loadfile(L, c_dbpath);
lua_createtable(L, 0, 1);
lua_pushliteral(L, "Entry");
lua_pushvalue(L, -4); // categories table
lua_newtable(L); // files loaded
lua_pushvalue(L, -4); // Used/unused table.
lua_newtable(L); // Empty table to record filenames loaded.
lua_pushcclosure(L, entry, 2);
lua_settable(L, -3);
lua_setfenv(L, -2);
lua_call(L, 0, 0); // Let errors go through
lua_setfenv(L, -2); // Put the Entry function in the global environment.
lua_call(L, 0, 0); // Execute the script database, letting errors go through.
/* Go through and remove all the used categories/scripts/directories, leaving
* only the unused ones. */
lua_pushnil(L);
while (lua_next(L, -2) != 0)
{
if (lua_toboolean(L, -1)) // category was used?
if (lua_toboolean(L, -1)) // If used
{
lua_pushvalue(L, -2);
lua_pushnil(L);
@@ -606,7 +676,7 @@ static int loadcategories (lua_State *L)
lua_pop(L, 1);
}
return 1; // unused tags (what's left in categories table)
return 1; // Table of unused categories/scripts/directories.
}
/* int init_rules (lua_State *L)