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---
-- Buffered network I/O helper functions.
--
-- The functions in this module can be used for delimiting data received by the
-- <code>nmap.receive_buf</code> function in the Network I/O API (which see).
-- @copyright Same as Nmap--See https://nmap.org/book/man-legal.html
local stdnse = require "stdnse"
local find = (require "string").find
_ENV = stdnse.module("match", stdnse.seeall)
--various functions for use with NSE's nsock:receive_buf - function
-- e.g.
-- sock:receive_buf(numbytes(80), true) - is the buffered version of
-- sock:receive_bytes(80) - i.e. it
-- returns exactly 80 bytes and no more
--- Return a function that allows delimiting at a certain number of bytes.
--
-- This function can be used to get a buffered version of
-- <code>sock:receive_bytes(n)</code> in case a script requires more than one
-- fixed-size chunk, as the unbuffered version may return more bytes than
-- requested and thus would require you to do the parsing on your own.
--
-- The <code>keeppattern</code> parameter to receive_buf should be set to
-- <code>true</code>, otherwise the string returned will be 1 less than
-- <code>num</code>
-- @param num Number of bytes.
-- @usage sock:receive_buf(match.numbytes(80), true)
-- @see nmap.receive_buf
numbytes = function(num)
local n = num
return function(buf)
if(#buf >=n) then
return n, n
end
return nil
end
end
--- Search for a pattern within a set number of bytes
--
-- This function behaves just like passing a pattern to receive_buf, but it
-- will only receive a predefined number of bytes before returning the buffer.
-- @param pattern The pattern to search for
-- @param within The number of bytes to consume
-- @usage sock:receive_buf(match.pattern_limit("\r\n", 80), true)
pattern_limit = function (pattern, within)
local n = within
return function(buf)
local left, right = find(buf, pattern)
if left then
return left, right
elseif #buf >= n then
return n, n
end
return nil
end
end
return _ENV;
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