libs/http/luasrc/http/protocol/conditionals.lua

   1 --[[
   2
   3 HTTP protocol implementation for LuCI - RFC2616 / 14.19, 14.24 - 14.28
   4 (c) 2008 Freifunk Leipzig / Jo-Philipp Wich <xm@leipzig.freifunk.net>
   5
   6 Licensed under the Apache License, Version 2.0 (the "License");
   7 you may not use this file except in compliance with the License.
   8 You may obtain a copy of the License at
   9
  10         http://www.apache.org/licenses/LICENSE-2.0
  11
  12 $Id$
  13
  14 ]]--
  15
  16 module("luci.http.protocol.conditionals", package.seeall)
  17
  18 local date = require("luci.http.protocol.date")
  19
  20
  21 -- 14.19 / ETag
  22 function mk_etag( stat )
  23         if stat ~= nil then
  24                 return string.format( "%x-%x-%x", stat.ino, stat.size, stat.mtime )
  25         end
  26 end
  27
  28 -- 14.24 / If-Match
  29 function if_match( req, stat )
  30         local h    = req.headers
  31         local etag = mk_etag( stat )
  32
  33         -- Check for matching resource
  34         if type(h['If-Match']) == "string" then
  35                 for ent in h['If-Match']:gmatch("([^, ]+)") do
  36                         if ( ent == '*' or ent == etag ) and stat ~= nil then
  37                                 return true
  38                         end
  39                 end
  40
  41                 return false, 412
  42         end
  43
  44         return true
  45 end
  46
  47 -- 14.25 / If-Modified-Since
  48 function if_modified_since( req, stat )
  49         local h = req.headers
  50
  51         -- Compare mtimes
  52         if type(h['If-Modified-Since']) == "string" then
  53                 local since = date.to_unix( h['If-Modified-Since'] )
  54
  55                 if stat == nil or since < stat.mtime then
  56                         return true
  57                 end
  58
  59                 return false, 304
  60         end
  61
  62         return true
  63 end
  64
  65 -- 14.26 / If-None-Match
  66 function if_none_match( req, stat )
  67         local h    = req.headers
  68         local etag = mk_etag( stat )
  69
  70         -- Check for matching resource
  71         if type(h['If-None-Match']) == "string" then
  72                 for ent in h['If-None-Match']:gmatch("([^, ]+)") do
  73                         if ( ent == '*' or ent == etag ) and stat ~= nil then
  74                                 if req.request_method == "get"  or
  75                                    req.request_method == "head"
  76                                 then
  77                                         h['ETag']          = mk_etag( stat )
  78                                         h['Last-Modified'] = date.to_http( stat.mtime )
  79
  80                                         return false, 304
  81                                 else
  82                                         return false, 412
  83                                 end
  84                         end
  85                 end
  86         end
  87
  88         return true
  89 end
  90
  91 -- 14.27 / If-Range
  92 function if_range( req, stat )
  93         -- Sorry, no subranges (yet)
  94         return false, 412
  95 end
  96
  97 -- 14.28 / If-Unmodified-Since
  98 function if_unmodified_since( req, stat )
  99         local h = req.headers
 100
 101         -- Compare mtimes
 102         if type(h['If-Unmodified-Since']) == "string" then
 103                 local since = date.to_unix( h['If-Unmodified-Since'] )
 104
 105                 if stat ~= nil and since <= stat.mtime then
 106                         return false, 412
 107                 end
 108         end
 109
 110         return true
 111 end