/nselib/nmap.luadoc

---
-- Interface with Nmap internals.
--
-- The <code>nmap</code> module is an interface with Nmap's internal functions
-- and data structures. The API provides target host details such as port
-- states and version detection results. It also offers an interface to the
-- Nsock library for efficient network I/O.
-- @copyright Same as Nmap--See http://nmap.org/book/man-legal.html

module "nmap"

--- Returns the debugging level as a non-negative integer.
--
-- The debugging level can be set with the <code>-d</code> option.
-- @return The debugging level.
-- @usage if nmap.debugging() > 0 then ... end
function debugging()

--- Determines whether Nmap was compiled with SSL support.
--
-- This can be used to avoid sending SSL probes when SSL is not available.
-- @return True if Nmap was compiled with SSL support, false otherwise.
function have_ssl()

--- Returns the version intensity as a non-negative integer.
--
-- The version intensity can be set for all version probes with the
-- <code>--version-intensity</code> option. The intensity for version scripts
-- can be overridden with the <code>script-intensity</code> script argument.
-- If overridden, nmap.version_intensity() returns the overridden value
-- automatically. If neither <code>--version-intensity</code> nor the script
-- argument <code>script-intensity</code> are used, the version intensity
-- defaults to 7.
-- When a version script is given by name with the <code>--script</code>
-- option, as opposed to being selected automatically due to <code>-sV</code>,
-- its version intensity is automatically set to maximum (9).
-- @return The version intensity.
-- @usage
-- portrule = function(host, port)
--   return ...
--          ...
--          and nmap.version_intensity() >= 7
--   end
function version_intensity()

--- Returns the verbosity level as a non-negative integer.
--
-- The verbosity level can be set with the <code>-v</code> option. When
-- a script is given by name with the <code>--script</code> option, as
-- opposed to being selected by default or by category, its verbosity
-- level is automatically increased by one.
-- @return The verbosity level.
-- @usage if nmap.verbosity() > 0 then ... end
function verbosity()

--- Returns whether a script should be able to perform privileged operations
--
-- @return True if Nmap is running privileged, false otherwise.
function is_privileged()

--- Resolves the specified host name using the optional address family and
-- returns a table containing all of the matching addresses.
--
-- If no address family is given, resolve() will return all addresses for the
-- name.
--
-- @param host Host name to resolve
-- @param family Address family string (such as "inet") to specify the type
-- of addresses returned
-- @see address_family
-- @return Status (true or false)
-- @return Table containing addresses resolved from the host name if status
-- is true, or an error string if status is false
-- @usage local status, t = nmap.resolve("www.kame.net", nmap.address_family())
function resolve(host, family)

--- Returns the address family Nmap is using.
--
-- For example, if Nmap is run with the -6 option, then "inet6" is returned.
--
-- @return The address family as a string ("inet" or "inet6")
-- @usage local family = nmap.address_family()
function address_family()

--- Returns the interface name (dnet-style) that Nmap is using.
--
-- For example in the pre-scanning (<code>"prerule"</code> scripts) phase
-- if Nmap is run with the <code>-e eth0</code>, then "eth0" can be
-- returned, however Nmap can return an other interface name since it
-- can determine the best interface suited for the job.
-- Other <code>"hostrule"</code> and <code>"portrule"</code> scripts
-- should use the interface field of the <code>host</code> table:
-- <code>host.interface</code>.
--
-- The result of this function can be used to get the interface information
-- table, example: <code>nmap.get_interface_info("eth0")</code>.
--
-- @return A string containing the interface name (dnet-style) on
-- success, or a nil value on failures.
-- @usage local interface_name = nmap.get_interface()
function get_interface()

--- Gets the interface network information.
--
-- This function takes a dnet-style interface name and returns a table
-- containing the network information of the interface.
--
-- Keys of the returned table:
-- * <code>device</code> The interface name, can be an interface alias.
-- * <code>shortname</code> A simple short name of the device.
-- * <code>netmask</code> The netmask bits (CIDR) of the interface.
-- * <code>address</code> The string representing the IP address assigned to the interface.
-- * <code>link</code> The string representing the hardware type of the interface. Possible values are: <code>"ethernet"</code>, <code>"loopback"</code>, <code>"p2p"</code> or <code>"other"</code>.
-- * <code>mac</code> MAC address (six-byte-long binary string) of the interface if the type of the interface is <code>"ethernet"</code>, otherwise it is <code>nil</code>.
-- * <code>broadcast</code> The string representing the broadcast address assigned to the interface if the interface type is <code>"ethernet"</code> and if the used address is IPv4, otherwise it is <code>nil</code>.
-- * <code>up</code> The state of the interface, possible values are <code>"up"</code> or <code>"down"</code>.
-- * <code>mtu</code> The MTU size of the interface.
--
-- @param interface_name The name of the interface.
-- @return Table containing the network information of the interface on
--  success, or nil and an error message on failures.
-- @usage local iface, err = nmap.get_interface_info("eth0")
function get_interface_info(interface_name)

--- Lists network interfaces
--
-- This script enumerates all network interfaces and returns a list of tables
-- containing information about every interface.
--
-- Keys of each table:
-- * <code>device</code> The interface name, can be an interface alias.
-- * <code>shortname</code> A simple short name of the device.
-- * <code>netmask</code> The netmask bits (CIDR) of the interface.
-- * <code>address</code> The string representing the IP address assigned to the interface.
-- * <code>link</code> The string representing the hardware type of the interface. Possible values are: <code>"ethernet"</code>, <code>"loopback"</code>, <code>"p2p"</code> or <code>"other"</code>.
-- * <code>mac</code> MAC address (six-byte-long binary string) of the interface if the type of the interface is <code>"ethernet"</code>, otherwise it is <code>nil</code>.
-- * <code>broadcast</code> The string representing the broadcast address assigned to the interface if the interface type is <code>"ethernet"</code> and if the used address is IPv4, otherwise it is <code>nil</code>.
-- * <code>up</code> The state of the interface, possible values are <code>"up"</code> or <code>"down"</code>.
-- * <code>mtu</code> The MTU size of the interface.
--
-- @return Array of tables containing information about every discovered interface.
-- @usage local interfaces, err = nmap.list_interfaces()
function list_interfaces()

--- Returns the TTL (time to live) value selected by the --ttl option
--
-- If there is no value specified or if the value specified with the --ttl
-- option is out of the range 0 to 255 (inclusive) this function returns 64,
-- which is the default TTL for an IP packet. This function would be most
-- useful in crafting packets, which we want to comply with the selected
-- Nmap TTL value.
--
-- @return A number containing the TTL value
-- @usage local ttl = nmap.get_ttl()
function get_ttl()

--- Returns the payload data length selected with the --data-length option
--
-- Used when a script is crafting ICMP packets and needs to comply with the
-- selected payload data length. If there is no value specified this function
-- returns 0 which is the default length of the ICMP payload for Nmap.
--
-- @return A number containing the value of the payload length
-- @usage local payload_length = nmap.get_payload_length
function get_payload_length()

--- Searches for the specified file relative to Nmap's search paths and returns
-- a string containing its path if it is found and readable (to the process).
-- Absolute paths and paths relative to the current directory will not be
-- searched.
--
-- If the file is not found, not readable, or is a directory, <code>nil</code>
-- is returned.
-- @usage
-- nmap.fetchfile("nmap-rpc") --> "/usr/local/share/nmap/nmap-rpc"
-- @param filename Filename to search for.
-- @return String representing the full path to the file or <code>nil</code>.
function fetchfile(filename)

--- Returns the timing level as a non-negative integer.
--
-- Possible return values vary from <code>0</code> to <code>5</code>,
-- corresponding to the six built-in Nmap timing templates. The timing level
-- can be set with the <code>-T</code> option.
-- @return The timing level.
function timing_level()

--- Gets a port table for a port on a given host.
--
-- This function takes a host table and a port table and returns a port table
-- for the queried port. The port table returned is similar in structure to the
-- ones passed to the <code>hostrule</code>, <code>portrule</code>, and
-- <code>action</code> functions. If the given port was not scanned the function
-- returns <code>nil</code>.
--
-- You can of course reuse the host and port tables passed to a script's rule
-- function. The purpose of this call is to be able to match scripts against
-- more than one open port. For example if the target host has an open port 22
-- and a running identd server, then you can write a script which will only fire
-- if both ports are open and there is an identification server on port 113.
-- While it is possible to specify IP addresses different to the currently
-- scanned target, the result will only be correct if the target is in the
-- currently scanned group of hosts.
-- @param host Host table, containing an <code>ip</code> field.
-- @param port Port table, containing <code>number</code> and
-- <code>protocol</code> fields.
-- @return A new port table holding the status and information for the port, or <code>nil</code>.
-- @usage p = nmap.get_port_state({ip="127.0.0.1"}, {number="80", protocol="tcp"})
function get_port_state(host, port)

--- Iterates over port tables matching protocol and state for a given host
--
-- This function takes a host table, previous port table, port protocol and
-- port state to return matching port tables on a host.
--
-- The first time you call this function, pass <code>nil</code> for the port
-- parameter to get the first matching port table.  From then on, pass the
-- previous port table returned by this function to the port parameter for the
-- next matching port table.
--
-- @param host Host table, containing an <code>ip</code> field
-- @param port Port table, containing a <code>number</code> field; or <code>nil</code>
-- for first port
-- @param proto Port protocol, such as <code>"tcp"</code>
-- @param state Port state, such as <code>"open"</code>
-- @return Next port table for host, or <code>nil</code> when exhausted
-- @usage port = nmap.get_ports(host, port, "tcp", "open")
function get_ports(host, port, proto, state)

--- Sets the state of a port on a given host.
--
-- Using this function, the final port state, reflected in Nmap's results, can
-- be changed for a target. This is useful when Nmap detects a port as
-- <code>open|filtered</code>, but the script successfully connects to that
-- port. In this case, the script can set the port state to <code>open</code>.
-- This function doesn't change the original port table passed a script's
-- action function.
-- @param host Host table, containing an <code>ip</code> field.
-- @param port Port table, containing <code>number</code> and
-- <code>protocol</code> fields.
-- @param state Port state, like <code>"open"</code> or <code>"closed"</code>.
function set_port_state(host, port, state)

--- Sets version information on a port.
--
-- NSE scripts are sometimes able to determine the service name and application
-- version listening on a port. A whole script category (<code>version</code>)
-- was designed for this purpose. This function is used to record version
-- information when it is discovered.
--
-- The host and port arguments to this function should either be the tables
-- passed to the action method or they should have the same structure. The port
-- argument specifies the port to operate on through its <code>number</code>
-- and <code>protocol</code> fields. and also contains the new version
-- information to set. The version detection fields this function looks at are
-- <code>name</code>, <code>product</code>, <code>version</code>,
-- <code>extrainfo</code>, <code>hostname</code>, <code>ostype</code>,
-- <code>devicetype</code>, <code>service_tunnel</code>, and <code>cpe</code>.
-- All these keys are optional.
--
-- The <code>probestate</code> argument describes the state in which the script
-- completed. It is a string, one of: <code>"hardmatched"</code>,
-- <code>"softmatched"</code>, <code>"nomatch"</code>,
-- <code>"tcpwrapped"</code>, or <code>"incomplete"</code>.
-- <code>"hardmatched"</code> is almost always used (and is the default),
-- as it signifies a
-- successful match. The other possible states are generally only used for
-- standard version detection rather than the NSE enhancement.
-- @param host Host table, containing an <code>ip</code> field.
-- @param port Port table, containing <code>number</code> and
-- <code>protocol</code> fields, as well as any additional version information
-- fields.
-- @param probestate The state of the probe: <code>"hardmatched"</code>,
-- <code>"softmatched"</code>, <code>"nomatch"</code>,
-- <code>"tcpwrapped"</code>, or <code>"incomplete"</code>.
function set_port_version(host, port, probestate)

--- Returns the current date and time in seconds.
-- @return The number of seconds since the epoch (on most systems this is
-- 01/01/1970) as a floating point value.
-- @usage local now = nmap.clock()
function clock()

--- Returns the current date and time in milliseconds.
-- @return The number of milliseconds since the epoch (on most systems this is
-- 01/01/1970).
-- @usage local now = nmap.clock_ms()
function clock_ms()

--- Create a mutex on an object.
--
-- This function returns another function that works as a mutex on the object
-- passed. This object can be any Lua data type except <code>nil</code>,
-- Booleans, and Numbers. The Mutex (the returned function) allows you to lock,
-- try to lock, and release the mutex.  The Mutex function takes only one
-- argument, which must be one of
-- * <code>"lock"</code>: makes a blocking lock on the mutex. If the mutex is busy then the thread will yield and wait. The function returns with the mutex locked.
-- * <code>"trylock"</code>: makes a non-blocking lock on the mutex. If the mutex is busy then it immediately returns a false value. Otherwise, the mutex locks the mutex and returns true.
-- * <code>"done"</code>: releases the mutex and allows another thread to lock it. If the thread does not have a lock on the mutex, an error will be raised.
-- * <code>"running"</code>: returns the thread locked on the mutex or <code>nil</code> if no thread is locked. This should only be used for debugging as it interferes with finished threads from being collected.
--
-- NSE maintains a weak reference to the Mutex function so other calls to
-- nmap.mutex with the same object will return the same function (Mutex);
-- however, if you discard your reference to the Mutex then it may be collected
-- and subsequent calls to nmap.mutex with the object will return a different
-- Mutex!
-- @param object Object to create a mutex for.
-- @return Mutex function which takes one of the following arguments:
-- <code>"lock"</code>, <code>"trylock"</code>, <code>"done"</code>, or
-- <code>"running"</code>.
-- @usage
-- id = "My Script's Unique ID"
--
-- local mutex = nmap.mutex(id)
-- function action(host, port)
--   mutex "lock"
--   -- do stuff
--   mutex "done"
--   return script_output
-- end
function mutex(object)

--- Create a condition variable for an object.
--
-- This function returns a function that works as a Condition Variable for the
-- given object parameter. The object can be any Lua data type except
-- <code>nil</code>, Booleans, and Numbers. The Condition Variable (returned
-- function) allows you wait, signal, and broadcast on the condition variable.
-- The Condition Variable function takes only one argument, which must be one of
-- * <code>"wait"</code>: Wait on the condition variable until another thread wakes us.
-- * <code>"signal"</code>: Wake up a single thread from the waiting set of threads for this condition variable.
-- * <code>"broadcast"</code>: Wake up all threads in the waiting set of threads for this condition variable.
--
-- NSE maintains a weak reference to the Condition Variable so other calls to
-- nmap.condvar with the same object will return the same function (Condition
-- Variable); however, if you discard your reference to the Condition
-- Variable then it may be collected; and, subsequent calls to nmap.condvar with
-- the object will return a different Condition Variable function!
--
-- In NSE, Condition Variables are typically used to coordinate with threads
-- created using the stdnse.new_thread facility. The worker threads must
-- wait until work is available that the master thread (the actual running
-- script) will provide. Once work is created, the master thread will awaken
-- one or more workers so that the work can be done.
--
-- It is important to check the predicate (the test to see if your worker
-- thread should "wait" or not) BEFORE and AFTER the call to wait. You are
-- not guaranteed spurious wakeups will not occur (that is, there is no
-- guarantee your thread will not be awakened when no thread called
-- <code>"signal"</code> or <code>"broadcast"</code> on the condition variable).
-- One important check for your worker threads, before and after waiting,
-- should be to check that the master script thread is still alive.
-- (To check that the master script thread is alive, obtain the "base" thread
-- using stdnse.base and use coroutine.status). You do not want your worker
-- threads to continue when the script has ended for reasons unknown to your
-- worker thread. You are guaranteed that all threads waiting on a
-- condition variable will be awakened if any thread that has accessed
-- the condition variable via <code>nmap.condvar</code> ends for any
-- reason. This is essential to prevent deadlock with threads
-- waiting for another thread to awaken
-- them that has ended unexpectedly.
-- @see stdnse.new_thread
-- @see stdnse.base
-- @param object Object to create a condition variable for.
-- @return ConditionVariable Condition variable function.
-- @usage
-- local myobject = {}
-- local cv = nmap.condvar(myobject)
-- cv "wait" -- waits until another thread calls cv "signal"
function condvar(object)

--- Creates a new exception handler.
--
-- This function returns an exception handler function. The exception handler is
-- meant to be wrapped around other function calls that may raise an exception.
-- A function raises an exception by making its first return value false and its
-- second return value a message describing the error. When an exception occurs,
-- the exception handler optionally calls a user-provided cleanup function, then
-- terminates the script. When an exception does not occur (the wrapped
-- function's first return value is true), the exception handler strips off the
-- first return value and returns the rest.
--
-- The optional cleanup function is passed as the sole argument to
-- <code>new_try</code>. It can be used to release sockets or other resources
-- before the script terminates.
--
-- A function that may raise an exception must follow the return protocol
-- understood by this function: on an exception its return values are
-- <code>false</code> or <code>nil</code> followed by an error message; on
-- success its return values are any true value followed by any other results.
-- @param handler User cleanup function (optional).
-- @usage
-- local result, socket, try, catch
--
-- result = ""
-- socket = nmap.new_socket()
-- catch = function()
--   socket:close()
-- end
-- try = nmap.new_try(catch)
-- try(socket:connect(host, port))
-- result = try(socket:receive_lines(1))
-- try(socket:send(result))
function new_try(handler)

--- Returns a new NSE socket object.
--
-- To allow for efficient and parallelizable network I/O, NSE provides an
-- interface to Nsock, the Nmap socket library. The smart callback mechanism
-- Nsock uses is fully transparent to NSE scripts. The main benefit of NSE's
-- sockets is that they never block on I/O operations, allowing many scripts to
-- be run in parallel. The I/O parallelism is fully transparent to authors of
-- NSE scripts. In NSE you can either program as if you were using a single
-- non-blocking socket or you can program as if your connection is blocking.
-- Seemingly blocking I/O calls still return once a specified timeout has been
-- exceeded.
--
-- NSE sockets are the recommended way to do network I/O. They support
-- <code>connect</code>-style sending and receiving over TCP and UDP (and SSL),
-- as well as raw socket receiving.
-- @param protocol a protocol string (optional, defaults to <code>"tcp"</code>).
-- @param af an address family string (optional, defaults to <code>"inet"</code>).
-- @return A new NSE socket.
-- @see pcap_open
-- @usage local socket = nmap.new_socket()
function new_socket(protocol, af)

--- Sets the local address of a socket.
--
-- This socket method sets the local address and port of a socket. It must be
-- called before <code>connect</code>. The address set by <code>bind</code>
-- overrides Nmap's source address and port set by the <code>-S</code> and
-- <code>-g</code> options.
-- @param addr Address string or <code>nil</code> (optional).
-- @param port Port number or <code>nil</code> (optional).
-- @return Status (true or false).
-- @return Error string (if status is false).
-- @usage
-- try = nmap.new_try()
-- try(socket:bind(nil, 53))
-- try(socket:bind("1.2.3.4"))
-- try(socket:bind("2001:db8::1"))
-- try(socket:bind("1.2.3.4", 53))
function bind(addr, port)

--- Establishes a connection.
--
-- This method puts a socket in a state ready for communication. It takes as
-- arguments a host descriptor (a host table, IP address, or hostname), a port
-- descriptor (a port table or number), and optionally a protocol. If given, the
-- protocol must be one of <code>"tcp"</code>, <code>"udp"</code> or
-- <code>"ssl"</code>. The default value for the protocol is
-- <code>port.protocol</code> if <code>port</code> is a port table, otherwise
-- <code>"tcp"</code>.
--
-- If <code>host</code> is a host table, it must contain at least one of the
-- keys <code>ip</code> or <code>name</code>. If <code>name</code>
-- is given, it is used to request the correct certificate in SSL connections.
-- Passing a string instead of a host table acts like <code>host.ip</code> and
-- <code>host.name</code> were set to the same value. If <code>port</code>
-- is a table, it must contain the <code>number</code> key.
--
-- On success the function returns a true value. On failure it returns a false
-- value (<code>false</code> or <code>nil</code>) and an error string. Those
-- strings are taken from the <code>gai_strerror</code> C function. They are
-- (with the error code in parentheses):
-- * <code>"Address family for hostname not supported"</code> (<code>EAI_ADDRFAMILY</code>)
-- * <code>"Temporary failure in name resolution"</code> (<code>EAI_AGAIN</code>)
-- * <code>"Bad value for ai_flags"</code> (<code>EAI_BADFLAGS</code>)
-- * <code>"Non-recoverable failure in name resolution"</code> (<code>EAI_FAIL</code>)
-- * <code>"ai_family not supported"</code> (<code>EAI_FAMILY</code>)
-- * <code>"Memory allocation failure"</code> (<code>EAI_MEMORY</code>)
-- * <code>"No address associated with hostname"</code> (<code>EAI_NODATA</code>)
-- * <code>"Name or service not known"</code> (<code>EAI_NONAME</code>)
-- * <code>"Servname not supported for ai_socktype"</code> (<code>EAI_SERVICE</code>)
-- * <code>"ai_socktype not supported"</code> (<code>EAI_SOCKTYPE</code>)
-- * <code>"System error"</code> (<code>EAI_SYSTEM</code>)
-- In addition to these standard system error messages there are two
-- NSE-specific errors:
-- * <code>"Sorry, you don't have OpenSSL"</code>: The protocol is <code>"ssl"</code> but Nmap was compiled without OpenSSL support.
-- * <code>"invalid connection method"</code>: The second parameter is not one of <code>"tcp"</code>, <code>"udp"</code>, and <code>"ssl"</code>.
-- @param host Host table, hostname or IP address.
-- @param port Port table or number.
-- @param protocol <code>"tcp"</code>, <code>"udp"</code>, or
-- <code>"ssl"</code> (default <code>"tcp"</code>, or whatever was set in
-- <code>new_socket</code>).
-- @return Status (true or false).
-- @return Error code (if status is false).
-- @see new_socket
-- @usage
-- local status, err = socket:connect(host, port)
-- if not status then
--     return string.format("Can't connect: %s", err)
-- end
function connect(host, port, protocol)

--- Reconnect the open (connected) socket with SSL.
--
-- It is sometimes desirable to request SSL over an established connection.
-- The internal buffers for the socket are cleared when the reconnection is
-- made. Any received data that has not yet been read through a call to receive
-- is lost.
-- @usage
-- local status, err = socket:reconnect_ssl()
-- if not status then
--   return string.format("Can't reconnect with ssl: %s", err)
-- end
function reconnect_ssl()

--- Sends data on an open socket.
--
-- This socket method sends the data contained in the data string through an
-- open connection. On success the function returns a true value. If the send
-- operation fails, the function returns a false value (<code>false</code> or
-- <code>nil</code>) along with an error string. The error strings are
-- * <code>"Trying to send through a closed socket"</code>: There was no call to <code>socket:connect</code> before the send operation.
-- * <code>"TIMEOUT"</code>: The operation took longer than the specified timeout for the socket.
-- * <code>"ERROR"</code>: An error occurred inside the underlying Nsock library.
-- * <code>"CANCELLED"</code>: The operation was cancelled.
-- * <code>"KILL"</code>: For example the script scan is aborted due to a faulty script.
-- * <code>"EOF"</code>: An EOF was read (probably will not occur for a send operation).
-- @param data The data to send.
-- @return Status (true or false).
-- @return Error code (if status is false).
-- @see new_socket
-- @usage local status, err = socket:send(data)
function send(data)

--- Sends data on an unconnected socket to a given destination.
--
-- Sockets that have not been connected do not have an implicit
-- destination address, so the <code>send</code> function doesn't work. Instead
-- the destination must be given with each send using this function. The
-- protocol and address family of the socket must have been set in
-- <code>new_socket</code>. On
-- success the function returns a true value. If the send operation fails, the
-- function returns a false value (<code>false</code> or <code>nil</code>) along
-- with an error string. The error strings are
-- * <code>"TIMEOUT"</code>: The operation took longer than the specified timeout for the socket.
-- * <code>"ERROR"</code>: An error occurred inside the underlying Nsock library.
-- * <code>"CANCELLED"</code>: The operation was cancelled.
-- * <code>"KILL"</code>: For example the script scan is aborted due to a faulty script.
-- * <code>"EOF"</code>: An EOF was read (probably will not occur for a send operation).
-- @param host The hostname or IP address to send to.
-- @param port The port number to send to.
-- @param data The data to send.
-- @return Status (true or false).
-- @return Error code (if status is false).
-- @usage local status, err = socket:sendto(host, port, data)
function sendto(host, port, data)

--- Receives data from an open socket.
--
-- The receive method does a non-blocking receive operation on an open socket.
-- On success the function returns true along with the received data. On
-- failure the function returns a false value (<code>false</code> or
-- <code>nil</code>) along with an error string. A failure occurs for example if
-- <code>receive</code> is called on a closed socket. The receive call returns
-- to the NSE script all the data currently stored in the receive buffer of the
-- socket. Error conditions are the same as for <code>send</code>.
-- @return Status (true or false).
-- @return Data (if status is true) or error string (if status is false).
-- @see new_socket
-- @usage local status, data = socket:receive()
function receive()

--- Receives lines from an open connection.
--
-- Tries to receive at least <code>n</code> lines from an open connection. A
-- line is a string delimited with <code>\n</code> characters.  If no data was
-- was received before the operation times out a <code>"TIMEOUT"</code> error
-- occurs. If even one character was received then it is returned with success.
-- On the other hand, if more than <code>n</code> lines were received, all are
-- returned, not just <code>n</code>. Use <code>stdnse.make_buffer</code> to
-- guarantee only one line is returned per call.
--
-- The return values and error codes are the same as for <code>send</code>.
-- @param n Minimum number of lines to read.
-- @return Status (true or false).
-- @return Data (if status is true) or error string (if status is false).
-- @see new_socket
-- @usage local status, lines = socket:receive_lines(1)
function receive_lines(n)

--- Receives bytes from an open connection.
--
-- Tries to receive at least <code>n</code> bytes from an open connection. Like
-- in <code>receive_lines</code>, <code>n</code> is the minimum amount of
-- characters we would like to receive. If more arrive, we get all of them. If
-- even one is received then it is returned. If no characters arrive before the
-- operation times out, a <code>"TIMEOUT"</code> error occurs.
--
-- The return values and error codes are the same as for <code>send</code>.
-- @param n Minimum number of bytes to read.
-- @return Status (true or false).
-- @return Data (if status is true) or error string (if status is false).
-- @see new_socket
-- @usage local status, bytes = socket:receive_bytes(1)
function receive_bytes(n)

--- Reads from a socket using a buffer and an arbitrary delimiter.
--
-- This method reads data from the network until it encounters the given
-- delimiter string (or matches the function passed in). This function
-- continues to read from the network until the delimiter is found or the
-- function times out.  If data is read beyond the delimiter, that data is
-- saved in a buffer for the next call to <code>receive_buf</code>.
--
-- The first argument may be either a pattern or a function. If a pattern, that
-- pattern is used to separate the data. If a function, it must take exactly
-- one parameter (the buffer) and its return values must be in the same format
-- as those of <code>string.find</code> (offsets to the start and the end of
-- the delimiter inside the buffer, or <code>nil</code> if the delimiter is not
-- found).  The nselib <code>match.lua</code> module provides functions for
-- matching against regular expressions or byte counts. These functions are
-- suitable as arguments to <code>receive_buf</code>.
--
-- The second argument to <code>receive_buf</code> is a Boolean value
-- controlling whether the delimiting string is returned along with the
-- received data (true) or discarded (false).
--
-- On success the function returns true along with the received data. On failure
-- the function returns <code>false</code> or <code>nil</code> along with an
-- receive error string. This function may also throw errors for incorrect usage.
-- @param delimiter A Lua pattern or a function with return values like those of
-- <code>string.find</code>.
-- @param keeppattern Whether to return the delimiter string with any returned
-- data.
-- @return Status (true or false).
-- @return Data (if status is true) or error string (if status is false).
-- @see new_socket
-- @see match
-- @usage local status, line = socket:receive_buf("\r?\n", false)
function receive_buf(delimiter, keeppattern)

--- Closes an open connection.
--
-- On success the function returns true. If the close fails, the function
-- returns <code>false</code> or <code>nil</code> and an error string. Currently
-- the only error message is <code>"Trying to close a closed socket"</code>,
-- which is issued if the socket has already been closed.
--
-- Sockets are subject to garbage collection. Should you forget to close a
-- socket, it will get closed before it gets deleted (on the next occasion Lua's
-- garbage collector is run). However since garbage collection cycles are
-- difficult to predict, it is considered good practice to close opened sockets.
-- @return Status (true or false).
-- @return Error code (if status is false).
-- @see new_socket
-- @usage socket:close()
function close()

--- Gets information about a socket.
--
-- This function returns information about a socket object. It returns five
-- values. If an error occurred, the first value is <code>false</code> or
-- <code>nil</code> and the second value is an error string. Otherwise the first
-- value is true and the remaining 4 values describe both endpoints of the TCP
-- connection. If you put the call inside an exception handler created by
-- <code>new_try</code> the status value is consumed. The call can be used for
-- example if you want to query an authentication server.
-- @return Status (true or false).
-- @return Local IP address (if status is true) or error string (if status is
-- false).
-- @return Local port number (if status is true).
-- @return Remote IP address (if status is true).
-- @return Remote port number (if status is true).
-- @see new_socket
-- @usage local status, lhost, lport, rhost, rport = socket:get_info()
function get_info()

--- Sets a timeout for socket input and output operations.
--
-- After this time, given in milliseconds, socket operations will time out and
-- return. The default value is 30,000 (30 seconds). The lowest allowed value is
-- 10 ms, since this is the granularity of NSE network I/O.
-- @param t Timeout in milliseconds.
-- @see new_socket
-- @usage socket:set_timeout(10000)
function set_timeout(t)

--- Opens a socket for raw packet capture.
--
-- @param device The dnet-style interface name of the device you want to capture
--               from.
-- @param snaplen The length of each packet you want to capture (similar to the
--                <code>-s</code> option to tcpdump)
-- @param promisc Boolean value for whether the interface should activate
--                promiscuous mode.
-- @param bpf A string describing a Berkeley Packet Filter expression (like
--            those provided to tcpdump).
-- @see new_socket, pcap_receive
-- @usage
-- local socket = nmap.new_socket()
-- socket:pcap_open("eth0", 64, false, "tcp")
function pcap_open(device, snaplen, promisc, bpf)

--- Receives a captured packet.
--
-- If an error or timeout occurs, the function returns false and an error
-- message. Otherwise, the function returns true followed by the packet length,
-- layer two header, layer three header and packet capture time.
-- @return Status (true or false).
-- @return The length of the captured packet (this may be smaller than the
--         actual packet length since packets are truncated when the
--         libpcap snaplen parameter is smaller than the total packet length).
-- @return Data from the second OSI layer (e.g. ethernet headers).
-- @return Data from the third OSI layer (e.g. IPv4 headers).
-- @return Packet capture time, as floating point seconds since the epoch
-- @see pcap_open
-- @usage status, plen, l2_data, l3_data, time = socket:pcap_receive()
function pcap_receive()

--- Closes a pcap device.
-- @see close, pcap_close
-- @usage socket:pcap_close()
function pcap_close()

---
-- Retrieves the SSL certificate of the peer. The returned value can be accessed
-- like a table and has the following members:
--
-- <code>
-- subject = { commonName = "...", countryName = "...",
--             { "2", "5", "4", "15" } = "...", ... },
-- issuer = { commonName = "...", ... },
-- pubkey = { type = "rsa", bits = 1024 },
-- validity = { notBefore = { year = 2020, month = 5, day = 5,
--                            hour = 0, min = 0, sec = 0 },
--              notAfter = { year = 2021, month = 5, day = 5,
--                           hour = 0, min = 0, sec = 0 } },
-- pem = "-----BEGIN CERTIFICATE-----\nMIIFxzCCBK+gAwIBAgIQX02QuADDB7CVj..."
-- </code>
--
-- It also has the following member functions:
--
-- * <code>digest(algorithm)</code> returns the digest of the certificate using the given digest algorithm, which is any of the strings returned by <code>openssl.supported_digests</code>, typically something like <code>"md5"</code> or <code>"sha1"</code>.
--
-- The <code>"subject"</code> and <code>"issuer"</code> fields hold each
-- distinguished name. Fields with an unknown OID are represented as an array
-- whose elements are the numeric components of the OID, encoded as strings.
--
-- The <code>"validity"</code> table has the members <code>"notBefore"</code>
-- and <code>"notAfter"</code>. Each of these is a table as returned by
-- <code>os.date("!*t")</code> if the date in the certificate could be parsed,
-- except that they lack the <code>"wday"</code> and <code>"yday"</code>
-- members. If the date could not be parsed, the value will be a string
-- containing the raw byte values of the field. If absent, the value will be
-- <code>nil</code>.
--
-- The <code>"pem"</code> field contains a PEM-encoded string of the entire
-- contents of the certificate.
-- @return A table as described above.
-- @usage
-- local s = nmap.new_socket()
-- local status, error = s:connect(host, port, "ssl")
-- if status then
--     local cert = s:get_ssl_certificate()
--     local digest = cert:digest("md5")
-- end
function get_ssl_certificate()

--- Creates a new dnet object, used to send raw packets.
-- @usage local dnet = nmap.new_dnet()
function new_dnet()

--- Opens an ethernet interface for raw packet sending.
--
-- An error (<code>"device is not valid ethernet interface"</code>) is thrown
-- in case the provided argument is not valid.
-- @param interface_name The dnet-style name of the interface to open.
-- @see new_dnet
-- @usage dnet:ethernet_open("eth0")
function ethernet_open(interface_name)

--- Sends a raw ethernet frame.
--
-- The dnet object must be associated with a previously opened interface. The
-- packet must include the IP and ethernet headers. If there was no previous
-- valid call to <code>ethernet_open</code> an error is thrown
-- (<code>"dnet is not valid opened ethernet interface"</code>).
-- @param packet An ethernet frame to send.
-- @see new_dnet
-- @usage dnet:ethernet_send(packet)
function ethernet_send(packet)

--- Closes an ethernet interface.
--
-- An error (<code>"device is not valid ethernet interface"</code>) is thrown
-- in case the provided argument is not valid.
-- @see new_dnet, ethernet_open
-- @usage dnet:ethernet_close()
function ethernet_close()

--- Opens a socket for raw IPv4 packet sending.
-- @see new_dnet
-- @usage dnet:ip_open()
function ip_open()

--- Sends a raw IPv4 or IPv6 packet.
--
-- The dnet object must be associated with a previously opened socket. The
-- packet must begin with an IP header. If there was no previous valid call
-- to <code>ip_open</code> an error is thrown.
-- @param packet An IP packet to send.
-- @param dst A destination address, as a host table or string. If omitted, the
-- destination address is read from the packet; however this is deprecated, because
-- the packet does not contain the scope ID required to send to certain IPv6
-- addresses.
-- @see new_dnet
-- @usage dnet:ip_send(packet, dst)
function ip_send(packet, dst)

--- Closes a raw IPv4 socket.
-- @see new_dnet, ip_open
-- @usage dnet:ip_close()
function ip_close()

--- Writes to a log file.
--
-- Writes <code>string</code> to <code>file</code> ("stdout" or "stderr").
-- Use stdnse.debug to print debug information based on the
-- debugging level.
-- @see stdnse.debug
function log_write(file, string)