Improve the script screen output. Fixes #1637

- properly handle indentation and line termination of multi-line command output
- strip off control characters
- replace tabs with spaces to maintain column alignment
- clean up documentation

scripts/ssh-run.nse

@@ -1,5 +1,6 @@
 local stdnse = require "stdnse"
 local shortport = require "shortport"
+local stringaux = require "stringaux"
 local table = require "table"
 local libssh2_util = require "libssh2-utility"
 
@@ -8,22 +9,25 @@ Runs remote command on ssh server and returns command output.
 ]]
 
 ---
--- @usage nmap -p 22 -v -d --script=ssh-run --datadir=./ \
+-- @usage nmap -p 22 --script=ssh-run \
 -- --script-args="ssh-run.cmd=ls -l /, ssh-run.username=myusername, ssh-run.password=mypassword" <target>
 --
 -- @output
--- 22/tcp open  ssh     syn-ack 0
+-- 22/tcp open  ssh
--- | run-remote:
+-- | ssh-run:
 -- |   output:
--- |     total 124
+-- |     total 91
--- | drwxr-xr-x   2 root       root        4096 Jun 23 09:34 bin
+-- |     drwxr-xr-x   2 root root  4096 Jun  5 11:56 bin
--- | drwxr-xr-x   3 root       root        4096 Jun 19 12:42 boot
+-- |     drwxr-xr-x   4 root root  3072 Jun  5 12:42 boot
--- | drwxr-xr-x   2 root       root        4096 Feb  6  2013 cdrom
+-- |     drwxrwxr-x   2 root root  4096 Jun 22  2017 cdrom
--- | drwxr-xr-x  16 root       root        4340 Jul 17 13:37 dev
+-- |     drwxr-xr-x  20 root root  4060 Jun 23 10:26 dev
--- | drwxr-xr-x 162 root       root       12288 Jul 20 12:10 etc
+-- |     drwxr-xr-x 127 root root 12288 Jun  5 11:56 etc
--- | drwxr-xr-x  15 root       root        4096 Jun 23 15:20 home
+-- |     drwxr-xr-x   3 root root  4096 Jun 22  2017 home
--- | ...
+-- ....
--- |_drwxr-xr-x  14 root       root        4096 Jun  6 14:58 var
+-- |_    drwxr-xr-x  13 root root  4096 Jul 20  2016 var
+--
+-- @xmloutput
+-- <elem key="output">total 91\x0D&#xa;drwxr-xr-x   2 root root  4096 Jun  5 11:56 bin\x0D&#xa;drwxr-xr-x   4 root root  3072 Jun  5 12:42 boot\x0D&#xa;drwxrwxr-x   2 root root  4096 Jun 22  2017 cdrom\x0D&#xa;drwxr-xr-x  20 root root  4060 Jun 23 10:26 dev\x0D&#xa;drwxr-xr-x 127 root root 12288 Jun  5 11:56 etc\x0D&#xa;drwxr-xr-x   3 root root  4096 Jun 22  2017 home\x0D&#xa;....\x0D&#xa;drwxr-xr-x  13 root root  4096 Jul 20  2016 var\x0D&#xa;</elem>
 --
 -- @args ssh-run.username    Username to authenticate as
 -- @args ssh-run.password    Password to use if using password authentication
@@ -47,6 +51,14 @@ local password = stdnse.get_script_args 'ssh-run.password'
 local privatekey = stdnse.get_script_args 'ssh-run.privatekey'
 local passphrase = stdnse.get_script_args 'ssh-run.passphrase'
 
+local function remove_tabs (str, tabsize)
+tabsize = tabsize or 8
+local out = str:gsub("(.-)\t", function (s)
+                                 return s .. (" "):rep(tabsize - #s % tabsize)
+                               end)
+  return out
+end
+
 function action (host, port)
   local conn = libssh2_util.SSHConnection:new()
   if not conn:connect(host, port) then
@@ -76,8 +88,16 @@ function action (host, port)
   stdnse.verbose("Running command: " .. cmd)
   local output, err_output = conn:run_remote(cmd)
   stdnse.verbose("Output of command: " .. output)
-  local result = stdnse.output_table()
+
-  result.output = {}
+  local out = stdnse.output_table()
-  table.insert(result.output, output)
+  out.output = output
-  return result
+
+  local txtout = {}
+  for _, line in ipairs(stringaux.strsplit("\r?\n", output:gsub("\r?\n$", ""))) do
+    local str = line:gsub("[^\t\x20-\x7f]", "")
+    table.insert(txtout, remove_tabs(str))
+  end
+  txtout.name = "output:"
+
+  return out, stdnse.format_output(true, {txtout})
 end