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| Enhanced cgiutils.lua file
Below is the improved cgiutils.lua file. It is similar to the earlier one, with extra functions for automating the production of the http and html headers and footers.
#! /usr/local/bin/lua
-- Lua utilities for CGI web use
-- Written by Nick Gammon - May 2006.
--[[
Copyright © 2006 Nick Gammon.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
The software is provided "as is", without warranty of any kind, express or
implied, including but not limited to the warranties of merchantability,
fitness for a particular purpose and noninfringement. In no event shall the
authors or copyright holders be liable for any claim, damages or other
liability, whether in an action of contract, tort or otherwise, arising from,
out of or in connection with the software or the use or other dealings in the
software.
--]]
-- global flags
done_http_header = false -- have we sent the HTTP header yet?
done_html_header = false -- have we sent the HTML header yet?
done_html_footer = false -- have we sent the HTTP footer yet?
-- split a string with delimiters into a table (reverse of table.concat)
function split (s, delim)
local t = {} -- results table
if s then
assert (type (delim) == "string" and string.len (delim) > 0,
"bad delimiter")
local start = 1
local pos
-- find each instance of a string followed by the delimiter
repeat
pos = string.find (s, delim, start, true) -- plain find
if pos then
table.insert (t, string.sub (s, start, pos - 1))
start = pos + string.len (delim)
end
until not pos
-- insert final one (after last delimiter)
table.insert (t, string.sub (s, start))
end -- not nil string
return t
end -- function split
-- trim leading and trailing spaces from a string
function trim (s)
return (string.gsub (string.gsub (s, "%s+$", ""), "^%s+", ""))
end -- trim
mysql_replacements = {
["\0"] = "\\0",
["\n"] = "\\n",
["\r"] = "\\r",
["\'"] = "\\\'",
["\""] = "\\\"",
["\026"] = "\\Z",
["\b"] = "\\b",
["\t"] = "\\t",
}
-- Fix SQL text by converting various characters to the format MySQL
-- will recognise in its string processor
--
-- Note that not all the escapes are necessary for internal SQL use,
-- however if data is being dumped to disk (eg. as SQL statements)
-- then it is handy for have things like \n and \r made more readable
-- See: http://dev.mysql.com/doc/refman/5.1/en/string-syntax.html
function fixsql (s)
return (string.gsub (tostring (s), "[%z\n\r\'\"\026\b\t]",
function (str)
return mysql_replacements [str] or str
end ))
end -- fixsql
html_replacements = {
["<"] = "<",
[">"] = ">",
["&"] = "&",
["\""] = """,
}
-- fix text so that < > and & are escaped
function fixhtml (s)
return (string.gsub (tostring (s), "[<>&\"]",
function (str)
return html_replacements [str] or str
end ))
end -- fixhtml
-- convert + to space
-- convert %xx where xx is hex characters, to the equivalent byte
function urldecode (s)
return (string.gsub (string.gsub (s, "+", " "),
"%%(%x%x)",
function (str)
return string.char (tonumber (str, 16))
end ))
end -- function urldecode
-- reverse of urldecode - converts characters that are not alphanumeric
-- into the form %xx (for use in cookies etc.)
function urlencode (s)
return (string.gsub (s, "%W",
function (str)
return string.format ("%%%02X", string.byte (str))
end ))
end -- function urlencode
-- process a single key=value pair from a GET line (or cookie, etc.)
function assemble_value (s, t)
assert (type (t) == "table")
local _, _, key, value = string.find (s, "(.-)=(.+)")
if key then
t [trim (urldecode (key))] = trim (urldecode (value))
end -- if we had key=value
end -- assemble_value
-- output a Lua table as an HTML table
function show_table (t)
local k, v
assert (type (t) == "table")
print "<table border=1 cellpadding=3>"
for k, v in pairs (t) do
print "<tr>"
print ("<th align=left >" .. fixhtml (k) .. "</th>" ..
"<td align=left >" .. fixhtml (v) .. "</td>")
print "</tr>"
end -- for
print "</table>"
end -- show_table
-- get query data, cookie data, post data
function get_user_input ()
local _, v
-- query data (stuff after the ? )
local get_data = {}
for _, v in ipairs (split (os.getenv ("QUERY_STRING"), "&")) do
assemble_value (v, get_data)
end -- for
-- cookies
local cookie_data = {}
for _, v in ipairs (split (os.getenv ("HTTP_COOKIE"), ";")) do
assemble_value (v, cookie_data)
end -- for
-- posted data (from a form)
local post_data = {}
local post_length = tonumber (os.getenv ("CONTENT_LENGTH")) or 0
if os.getenv ("REQUEST_METHOD") == "POST" and post_length > 0 then
for _, v in ipairs (split (io.read (post_length), "&")) do
assemble_value (v, post_data)
end -- for
end -- if post
return get_data, cookie_data, post_data, os.getenv ("REQUEST_METHOD")
end -- function get_user_input
-- show a standard HTTP header with optional cookies
function show_http_header (cookies)
assert (not done_http_header, "Too many HTTP headers")
print ("Content-Type: text/html; charset=iso-8859-1")
print ("X-Powered-By: cgiutils.lua written by Nick Gammon")
-- output a Set-Cookie line for each cookie in the table
if cookies then
assert (type (cookies) == "table")
for k, v in pairs (cookies) do
print ("Set-Cookie: " .. urlencode (k) .. "=" .. urlencode (v))
end -- for each cookie
end -- we have cookies
print ("") -- blank line separates header from body
done_http_header = true
end -- function show_http_header
-- show a standard HTML header with optional title, and other free-format things
-- the "other" stuff could be things like stylesheets, links, etc.
function show_html_header (title, other)
assert (not done_html_header, "Too many HTML headers")
if not done_http_header then
show_http_header ()
end
print ('<?xml version="1.0" encoding="iso-8859-1"?>')
print ('<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">')
print ('<html lang="en">')
print ('<head>')
if title then
print ('<title>' .. fixhtml (title) .. '</title>')
end -- having title
if other then
print (other)
end -- having other stuff
print ('</head>')
print ('<body>')
done_html_header = true
end -- function show_html_header
-- wrap up with an HTML footer
function show_html_footer ()
assert (not done_html_footer, "Too many HTML footers")
print ('</body>')
print ('</html>')
done_html_footer = true
end -- function show_html_footer
-- helper function to show an error in inverse bold coloured text
function show_error (theerror)
if not done_html_header then
show_html_header ("Error on web page")
end
local colour_error_text = "#FFFFFF" -- white
local colour_error_bgnd = "#A52A2A" -- brown
local family = "sans-serif"
local size = "150%"
local weight = "bolder"
-- style string for the error message
local style = string.format (
'color: %s; ' ..
'background: %s; ' ..
'font-family: %s; ' ..
'font-size: %s; ' ..
'font-weight: %s;',
colour_error_text,
colour_error_bgnd,
family,
size,
weight)
-- show error in desired style
print (string.format ('<p><span style="%s"> %s </span></p>',
style,
fixhtml (theerror)))
end -- end of show_error
-- Call this for things like script errors - it shows the error and exits
function major_problem (why)
if not done_html_header then
show_html_header ("Script error on web page")
end
print ("<h3>We apologise that there has been a problem with the web server ...</h3>\n")
print ("<hr>")
print ("<code><pre>" .. fixhtml (why) .. "</pre></code>")
print ("<p>Error occurred on " .. os.date ("%#x at %X") .. "</p>\n")
print ("<hr>")
show_html_footer ()
os.exit (1) -- let's stop while we are ahead :)
end -- function major_problem
-- this function is run in protected mode in case the script page has errors
function load_page ()
-- get local locale
os.setlocale ("", "time")
-- get GET, COOKIE, POST data, and request method
get_data, cookie_data, post_data, request_method = get_user_input ()
local scriptname = os.getenv ("PATH_INFO")
-- validity check on requested filename
if not scriptname or
string.find (scriptname, "..", 1, true) or
not string.find (scriptname, "/%a+/[%a%d_%-]+%.lua")
then
return show_error ("That URL is not valid")
end -- if
scriptname = "." .. scriptname -- make local path
-- check page exists, to avoid annoying user with Lua traceback message
local f, err1, err2 = io.open (scriptname)
if f then
f:close () -- we found the file, close it now
else
return show_error ("The requested page does not exist")
end -- if
-- run the file specified in the rest of the URL
dofile (scriptname)
end -- load_page
-- main code starts here
ok, error = xpcall (load_page, _TRACEBACK)
if not ok then
major_problem (error)
end -- error in page
-- ensure footer shown
if done_html_header and not done_html_footer then
show_html_footer ()
end -- if
[EDIT]
Changed on 4th May 2006, to add various extra functionality:
- Checking inside show_http_header, show_html_header and show_html_footer to ensure none of these are done twice.
- Automatic footer generation if not done by the called script.
- New function urlencode - this encodes a URL (reverse of urldecode) so that things like ';' are converted to '%3B'. This is used internally when setting a cookie.
- Improved show_error function - colours the error message using <span> rather than a single-item table.
- Improvements to load_page to do further checks on the requested script file name (using a regular expression). It also checks if the requested script file exists and if not gives a specific error message to that effect.
- Fixed bug in split function (pos cannot be a local variable)
- Added license so that you may use this software on your own web pages.
[EDIT]
Changed around 12 September 2006 to fix problems with getting POST data from some web servers using certain browsers. *cough**cough*Safari*cough* |
- Nick Gammon
www.gammon.com.au, www.mushclient.com | | Top |
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