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 --- LuCI http protocol implementation - HTTP/1.1 bits.
  17 -- This class provides basic ETag handling and implements most of the
  18 -- conditional HTTP/1.1 headers specified in RFC2616 Sct. 14.24 - 14.28 .
  19 module("luci.http.protocol.conditionals", package.seeall)
  20
  21 local date = require("luci.http.protocol.date")
  22
  23
  24 --- Implement 14.19 / ETag.
  25 -- @param stat  A file.stat structure
  26 -- @return              String containing the generated tag suitable for ETag headers
  27 function mk_etag( stat )
  28         if stat ~= nil then
  29                 return string.format( '"%x-%x-%x"', stat.ino, stat.size, stat.mtime )
  30         end
  31 end
  32
  33 --- 14.24 / If-Match
  34 -- Test whether the given message object contains an "If-Match" header and
  35 -- compare it against the given stat object.
  36 -- @param req   HTTP request message object
  37 -- @param stat  A file.stat object
  38 -- @return              Boolean indicating wheather the precondition is ok
  39 -- @return              Alternative status code if the precondition failed
  40 function if_match( req, stat )
  41         local h    = req.headers
  42         local etag = mk_etag( stat )
  43
  44         -- Check for matching resource
  45         if type(h['If-Match']) == "string" then
  46                 for ent in h['If-Match']:gmatch("([^, ]+)") do
  47                         if ( ent == '*' or ent == etag ) and stat ~= nil then
  48                                 return true
  49                         end
  50                 end
  51
  52                 return false, 412
  53         end
  54
  55         return true
  56 end
  57
  58 --- 14.25 / If-Modified-Since
  59 -- Test whether the given message object contains an "If-Modified-Since" header
  60 -- and compare it against the given stat object.
  61 -- @param req   HTTP request message object
  62 -- @param stat  A file.stat object
  63 -- @return              Boolean indicating wheather the precondition is ok
  64 -- @return              Alternative status code if the precondition failed
  65 -- @return              Table containing extra HTTP headers if the precondition failed
  66 function if_modified_since( req, stat )
  67         local h = req.headers
  68
  69         -- Compare mtimes
  70         if type(h['If-Modified-Since']) == "string" then
  71                 local since = date.to_unix( h['If-Modified-Since'] )
  72
  73                 if stat == nil or since < stat.mtime then
  74                         return true
  75                 end
  76
  77                 return false, 304, {
  78                         ["ETag"]          = mk_etag( stat );
  79                         ["Date"]          = date.to_http( os.time() );
  80                         ["Last-Modified"] = date.to_http( stat.mtime )
  81                 }
  82         end
  83
  84         return true
  85 end
  86
  87 --- 14.26 / If-None-Match
  88 -- Test whether the given message object contains an "If-None-Match" header and
  89 -- compare it against the given stat object.
  90 -- @param req   HTTP request message object
  91 -- @param stat  A file.stat object
  92 -- @return              Boolean indicating wheather the precondition is ok
  93 -- @return              Alternative status code if the precondition failed
  94 -- @return              Table containing extra HTTP headers if the precondition failed
  95 function if_none_match( req, stat )
  96         local h    = req.headers
  97         local etag = mk_etag( stat )
  98
  99         -- Check for matching resource
 100         if type(h['If-None-Match']) == "string" then
 101                 for ent in h['If-None-Match']:gmatch("([^, ]+)") do
 102                         if ( ent == '*' or ent == etag ) and stat ~= nil then
 103                                 if req.request_method == "get"  or
 104                                    req.request_method == "head"
 105                                 then
 106                                         return false, 304, {
 107                                                 ["ETag"]          = mk_etag( stat );
 108                                                 ["Date"]          = date.to_http( os.time() );
 109                                                 ["Last-Modified"] = date.to_http( stat.mtime )
 110                                         }
 111                                 else
 112                                         return false, 412
 113                                 end
 114                         end
 115                 end
 116         end
 117
 118         return true
 119 end
 120
 121 -- 14.27 / If-Range
 122 -- The If-Range header is currently not implemented due to the lack of general
 123 -- byte range stuff in luci.http.protocol . This function will always return
 124 -- false, 412 to indicate a failed precondition.
 125 -- @param req   HTTP request message object
 126 -- @param stat  A file.stat object
 127 -- @return              Boolean indicating wheather the precondition is ok
 128 -- @return              Alternative status code if the precondition failed
 129 function if_range( req, stat )
 130         -- Sorry, no subranges (yet)
 131         return false, 412
 132 end
 133
 134 -- 14.28 / If-Unmodified-Since
 135 -- Test whether the given message object contains an "If-Unmodified-Since"
 136 -- header and compare it against the given stat object.
 137 -- @param req   HTTP request message object
 138 -- @param stat  A file.stat object
 139 -- @return              Boolean indicating wheather the precondition is ok
 140 -- @return              Alternative status code if the precondition failed
 141 function if_unmodified_since( req, stat )
 142         local h = req.headers
 143
 144         -- Compare mtimes
 145         if type(h['If-Unmodified-Since']) == "string" then
 146                 local since = date.to_unix( h['If-Unmodified-Since'] )
 147
 148                 if stat ~= nil and since <= stat.mtime then
 149                         return false, 412
 150                 end
 151         end
 152
 153         return true
 154 end