1 files changed, 62 insertions, 0 deletions
diff --git a/nselib/match.lua b/nselib/match.lua
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+++ b/nselib/match.lua
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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;