Library `stdnse`

Standard Nmap Scripting Engine functions. This module contains various handy functions that are too small to justify modules of their own.

Copyright © Same as Nmap--See https://nmap.org/book/man-legal.html

Source: https://svn.nmap.org/nmap/nselib/stdnse.lua

Functions

base (): Returns the base coroutine of the running script.
clock_ms (): Returns the current time in milliseconds since the epoch
clock_us (): Returns the current time in microseconds since the epoch
debug (level, fmt, ...): Prints a formatted debug message if the current debugging level is greater than or equal to a given level.
format_mac (mac): Format a MAC address as colon-separated hex bytes.
format_output (status, data, indent): This function is deprecated.
fromhex (hex): Decode a hexadecimal string to raw bytes
get_hostname (host): Get the best possible hostname for the given host. This can be the target as given on the commandline, the reverse dns name, or simply the ip address.
get_script_args (..., Arguments): Parses the script arguments passed to the --script-args option.
get_timeout (host, max_timeout, min_timeout): Returns a conservative timeout for a host
make_buffer (socket, sep): Return a wrapper closure around a socket that buffers socket reads into chunks separated by a pattern.
module (name, ...): Module function that mimics some behavior of Lua 5.1 module function.
new_thread (main, ...): This function allows you to create worker threads that may perform network tasks in parallel with your script thread.
output_table (): Return a table that keeps elements in order of insertion.
parse_timespec (timespec): Parses a time duration specification, which is a number followed by a unit, and returns a number of seconds.
pretty_printer (obj, printer): A pretty printer for Lua objects.
print_debug (level, fmt, ...): Deprecated version of debug(), kept for now to prevent the script id from being printed twice. Scripts should use debug() and not pass SCRIPT_NAME
print_verbose (level, fmt, ...): Deprecated version of verbose(), kept for now to prevent the script id from being printed twice. Scripts should use verbose() and not pass SCRIPT_NAME
registry_add_array (subkeys, value, allow_duplicates): Add an item to an array in the registry, creating all sub-keys if necessary.
registry_add_table (subkeys, key, value, allow_duplicates): Similar to registry_add_array, except instead of adding a value to the end of an array, it adds a key:value pair to the table.
registry_get (subkeys): Retrieve an item from the registry, checking if each sub-key exists. If any key doesn't exist, return nil.
seeall (env): Change environment to load global variables.
silent_require (): The Lua Require Function with errors silenced.
sleep (t): Sleeps for a given amount of time.
string_or_blank (string, blank): Either return the string itself, or return "<blank>" (or the value of the second parameter) if the string was blank or nil.
tobinary (n): Converts the given number, n, to a string in a binary number format (12 becomes "1100"). Leading 0s not stripped.
tohex (s, options): Encode a string or integer in hexadecimal (12 becomes "c", "AB" becomes "4142").
tooctal (n): Converts the given number, n, to a string in an octal number format (12 becomes "14").
verbose (level, fmt, ...): Prints a formatted verbosity message if the current verbosity level is greater than or equal to a given level.

Functions

base ()

Returns the base coroutine of the running script.

A script may be resuming multiple coroutines to facilitate its own collaborative multithreading design. Because there is a "root" or "base" coroutine that lets us determine whether the script is still active (that is, the script did not end, possibly due to an error), we provide this stdnse.base function that will retrieve the base coroutine of the script. This base coroutine is the coroutine that runs the action function.

The base coroutine is useful for many reasons but here are some common uses:

We want to attribute the ownership of an object (perhaps a network socket) to a script.
We want to identify if the script is still alive.

Return value:

coroutine Returns the base coroutine of the running script.

clock_ms ()

Returns the current time in milliseconds since the epoch

Return value:

The current time in milliseconds since the epoch

clock_us ()

Returns the current time in microseconds since the epoch

Return value:

The current time in microseconds since the epoch

debug (level, fmt, ...)

Prints a formatted debug message if the current debugging level is greater than or equal to a given level.

This is a convenience wrapper around nmap.log_write. The first optional numeric argument, level, is used as the debugging level necessary to print the message (it defaults to 1 if omitted). All remaining arguments are processed with Lua's string.format function.

If known, the output includes some context based information: the script identifier and the target ip/port (if there is one). If the debug level is at least 2, it also prints the base thread identifier and whether it is a worker thread or the controller thread.

Parameters

level: Optional debugging level.
fmt: Format string.
...: Arguments to format.

format_mac (mac)

Format a MAC address as colon-separated hex bytes.

Parameters

mac: The MAC address in binary, such as host.mac_addr

Return value:

The MAC address in XX:XX:XX:XX:XX:XX format

format_output (status, data, indent)

This function is deprecated.

Please use structured NSE output instead: https://nmap.org/book/nse-api.html#nse-structured-output

Takes a table of output on the commandline and formats it for display to the user.

This is basically done by converting an array of nested tables into a string. In addition to numbered array elements, each table can have a 'name' and a 'warning' value. The 'name' will be displayed above the table, and 'warning' will be displayed, with a 'WARNING' tag, if and only if debugging is enabled.

Here's an example of a table:

  local domains = {}
  domains['name'] = "DOMAINS"
  table.insert(domains, 'Domain 1')
  table.insert(domains, 'Domain 2')

  local names = {}
  names['name'] = "NAMES"
  names['warning'] = "Not all names could be determined!"
  table.insert(names, "Name 1")

  local response = {}
  table.insert(response, "Apple pie")
  table.insert(response, domains)
  table.insert(response, names)

  return stdnse.format_output(true, response)

With debugging enabled, this is the output:

  Host script results:
  |  smb-enum-domains:
  |    Apple pie
  |    DOMAINS
  |      Domain 1
  |      Domain 2
  |    NAMES (WARNING: Not all names could be determined!)
  |_     Name 1

Parameters

status: A boolean value dictating whether or not the script succeeded. If status is false, and debugging is enabled, 'ERROR' is prepended to every line. If status is false and debugging is disabled, no output occurs.
data: The table of output.
indent: Used for indentation on recursive calls; should generally be set to nil when calling from a script.

Return value:

nil, if data is empty, otherwise a multiline string.

fromhex (hex)

Decode a hexadecimal string to raw bytes

The string can contain any amount of whitespace and capital or lowercase hexadecimal digits. There must be an even number of hex digits, since it takes 2 hex digits to make a byte.

Parameters

hex: A string in hexadecimal representation

Return values:

A string of bytes or nil if string could not be decoded
Error message if string could not be decoded

get_hostname (host)

Get the best possible hostname for the given host. This can be the target as given on the commandline, the reverse dns name, or simply the ip address.

Parameters

host: The host table (or a string that'll simply be returned).

Return value:

The best possible hostname, as a string.

get_script_args (..., Arguments)

Parses the script arguments passed to the --script-args option.

Parameters

...
Arguments: Script arguments to check.

Usage:

--script-args 'script.arg1=value,script.arg3,script-x.arg=value'
local arg1, arg2, arg3 = get_script_args('script.arg1','script.arg2','script.arg3')
     => arg1 = "value"
     => arg2 = nil
     => arg3 = 1

--script-args 'displayall,unsafe,script-x.arg=value,script-y.arg=value'
local displayall, unsafe = get_script_args('displayall','unsafe')
     => displayall = 1
     => unsafe     = 1

--script-args 'dns-cache-snoop.mode=timed,dns-cache-snoop.domains={host1,host2}'
local mode, domains = get_script_args('dns-cache-snoop.mode',
                                      'dns-cache-snoop.domains')
     => mode    = "timed"
     => domains = {"host1","host2"}

Return value:

Arguments values.

get_timeout (host, max_timeout, min_timeout)

Returns a conservative timeout for a host

If the host parameter is a NSE host table with a times.timeout attribute, then the return value is the host timeout scaled according to the max_timeout. The scaling factor is defined by a linear formula such that (max_timeout=8000, scale=2) and (max_timeout=1000, scale=1)

Parameters

host: The host object to base the timeout on. If this is anything but a host table, the max_timeout is returned.
max_timeout: The maximum timeout in milliseconds. This is the default timeout used if there is no host.times.timeout. Default: 8000
min_timeout: The minimum timeout in milliseconds that will be returned. Default: 1000

Usage:

assert(host.times.timeout == 1.3)
 assert(get_timeout() == 8000)
 assert(get_timeout(nil, 5000) == 5000)
 assert(get_timeout(host) == 2600)
 assert(get_timeout(host, 10000, 3000) == 3000)

Return value:

The timeout in milliseconds, suitable for passing to set_timeout

make_buffer (socket, sep)

Return a wrapper closure around a socket that buffers socket reads into chunks separated by a pattern.

This function operates on a socket attempting to read data. It separates the data by sep and, for each invocation, returns a piece of the separated data. Typically this is used to iterate over the lines of data received from a socket (sep = "\r?\n"). The returned string does not include the separator. It will return the final data even if it is not followed by the separator. Once an error or EOF is reached, it returns nil, msg. msg is what is returned by nmap.receive_lines.

Parameters

socket: Socket for the buffer.
sep: Separator for the buffered reads.

Return values:

Data from socket reads or nil on EOF or error.
Error message, as with receive_lines.

module (name, ...)

Module function that mimics some behavior of Lua 5.1 module function.

This convenience function returns a module environment to set the _ENV upvalue. The _NAME, _PACKAGE, and _M fields are set as in the Lua 5.1 version of this function. Each option function (e.g. stdnse.seeall) passed is run with the new environment, in order.

Parameters

name: The module name.
...: Option functions which modify the environment of the module.

Usage:

  _ENV = stdnse.module(name, stdnse.seeall, require "strict");

Parameters

main: The main function of the worker thread.
...: The arguments passed to the main worker thread.

Usage:

local requests = {"/", "/index.html", --[[ long list of objects ]]}

function thread_main (host, port, responses, ...)
 local condvar = nmap.condvar(responses);
 local what = {n = select("#", ...), ...};
 local allReqs = nil;
 for i = 1, what.n do
   allReqs = http.pGet(host, port, what[i], nil, nil, allReqs);
 end
 local p = assert(http.pipeline(host, port, allReqs));
 for i, response in ipairs(p) do responses[#responses+1] = response end
 condvar "signal";
end

function many_requests (host, port)
 local threads = {};
 local responses = {};
 local condvar = nmap.condvar(responses);
 local i = 1;
 repeat
   local j = math.min(i+10, #requests);
   local co = stdnse.new_thread(thread_main, host, port, responses,
       table.unpack(requests, i, j));
   threads[co] = true;
   i = j+1;
 until i > #requests;
 repeat
   condvar "wait";
   for thread in pairs(threads) do
     if coroutine.status(thread) == "dead" then threads[thread] = nil end
   end
 until next(threads) == nil;
 return responses;
end

Return values:

co The base coroutine of the worker thread.
info A query function used to obtain status information of the worker.

output_table ()

Return a table that keeps elements in order of insertion.

The pairs function, called on a table returned by this function, will yield elements in the order they were inserted. This function is meant to be used to construct output tables returned by scripts.

Reinserting a key that is already in the table does not change its position in the order. However, removing a key by assigning to nil and then doing another assignment will move the key to the end of the order.

Return value:

An ordered table.

parse_timespec (timespec)

Parses a time duration specification, which is a number followed by a unit, and returns a number of seconds.

The unit is optional and defaults to seconds. The possible units (case-insensitive) are

ms: milliseconds,
s: seconds,
m: minutes,
h: hours.

In case of a parsing error, the function returns nil followed by an error message.

Parameters

timespec: A time specification string.

Usage:

parse_timespec("10") --> 10
parse_timespec("10ms") --> 0.01
parse_timespec("10s") --> 10
parse_timespec("10m") --> 600
parse_timespec("10h") --> 36000
parse_timespec("10z") --> nil, "Can't parse time specification \"10z\" (bad unit \"z\")"

Return value:

A number of seconds, or nil followed by an error message.

pretty_printer (obj, printer)

A pretty printer for Lua objects.

Takes an object (usually a table) and prints it using the printer function. The printer function takes a sole string argument and will be called repeatedly.

Parameters

obj: The object to pretty print.
printer: The printer function.

print_debug (level, fmt, ...)

Deprecated version of debug(), kept for now to prevent the script id from being printed twice. Scripts should use debug() and not pass SCRIPT_NAME

Parameters

level
fmt
...

print_verbose (level, fmt, ...)

Deprecated version of verbose(), kept for now to prevent the script id from being printed twice. Scripts should use verbose() and not pass SCRIPT_NAME

Parameters

level
fmt
...

registry_add_array (subkeys, value, allow_duplicates)

Add an item to an array in the registry, creating all sub-keys if necessary.

For example, calling: registry_add_array({'192.168.1.100', 'www', '80', 'pages'}, 'index.html') Will create nmap.registry['192.168.1.100'] as a table, if necessary, then add a table under the 'www' key, and so on. 'pages', finally, is treated as an array and the value given is added to the end.

Parameters

subkeys
value
allow_duplicates

registry_add_table (subkeys, key, value, allow_duplicates)

Similar to registry_add_array, except instead of adding a value to the end of an array, it adds a key:value pair to the table.

Parameters

subkeys
key
value
allow_duplicates

registry_get (subkeys)

Retrieve an item from the registry, checking if each sub-key exists. If any key doesn't exist, return nil.

Parameters

subkeys

seeall (env)

Change environment to load global variables.

Option function for use with stdnse.module. It is the same as package.seeall from Lua 5.1.

Parameters

env: Environment to change.

Usage:

 _ENV = stdnse.module(name, stdnse.seeall);

Usage:

stdnse.silent_require "openssl"

sleep (t)

Sleeps for a given amount of time.

This causes the program to yield control and not regain it until the time period has elapsed. The time may have a fractional part. Internally, the timer provides millisecond resolution.

Parameters

t: Time to sleep, in seconds.

Usage:

stdnse.sleep(1.5)

string_or_blank (string, blank)

Either return the string itself, or return "<blank>" (or the value of the second parameter) if the string was blank or nil.

Parameters

string: The base string.
blank: The string to return if string was blank

Return value:

Either string or, if it was blank, blank

tobinary (n)

Converts the given number, n, to a string in a binary number format (12 becomes "1100"). Leading 0s not stripped.

Parameters

n: Number to convert.

Return value:

String in binary format.

tohex (s, options)

Encode a string or integer in hexadecimal (12 becomes "c", "AB" becomes "4142").

An optional second argument is a table with formatting options. The possible fields in this table are

separator: A string to use to separate groups of digits.
group: The size of each group of digits between separators. Defaults to 2, but has no effect if separator is not also given.

Parameters

s: String or number to be encoded.
options: Table specifying formatting options.

Usage:

stdnse.tohex("abc") --> "616263"
stdnse.tohex("abc", {separator = ":"}) --> "61:62:63"
stdnse.tohex("abc", {separator = ":", group = 4}) --> "61:6263"
stdnse.tohex(123456) --> "1e240"
stdnse.tohex(123456, {separator = ":"}) --> "1:e2:40"
stdnse.tohex(123456, {separator = ":", group = 4}) --> "1:e240"

Return value:

String in hexadecimal format.

tooctal (n)

Converts the given number, n, to a string in an octal number format (12 becomes "14").

Parameters

n: Number to convert.

Return value:

String in octal format.

verbose (level, fmt, ...)

Prints a formatted verbosity message if the current verbosity level is greater than or equal to a given level.

This is a convenience wrapper around nmap.log_write. The first optional numeric argument, level, is used as the verbosity level necessary to print the message (it defaults to 1 if omitted). All remaining arguments are processed with Lua's string.format function.

If known, the output includes some context based information: the script identifier. If the verbosity level is at least 2, it also prints the target ip/port (if there is one)

Parameters

level: Optional verbosity level.
fmt: Format string.
...: Arguments to format.

Library stdnse

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Library `stdnse`