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