modules/luci-base/luasrc/http/protocol/conditionals.lua

   1 -- Copyright 2008 Freifunk Leipzig / Jo-Philipp Wich <jow@openwrt.org>
   2 -- Licensed to the public under the Apache License 2.0.
   3
   4 --- LuCI http protocol implementation - HTTP/1.1 bits.
   5 -- This class provides basic ETag handling and implements most of the
   6 -- conditional HTTP/1.1 headers specified in RFC2616 Sct. 14.24 - 14.28 .
   7 module("luci.http.protocol.conditionals", package.seeall)
   8
   9 local date = require("luci.http.protocol.date")
  10
  11
  12 --- Implement 14.19 / ETag.
  13 -- @param stat  A file.stat structure
  14 -- @return              String containing the generated tag suitable for ETag headers
  15 function mk_etag( stat )
  16         if stat ~= nil then
  17                 return string.format( '"%x-%x-%x"', stat.ino, stat.size, stat.mtime )
  18         end
  19 end
  20
  21 --- 14.24 / If-Match
  22 -- Test whether the given message object contains an "If-Match" header and
  23 -- compare it against the given stat object.
  24 -- @param req   HTTP request message object
  25 -- @param stat  A file.stat object
  26 -- @return              Boolean indicating whether the precondition is ok
  27 -- @return              Alternative status code if the precondition failed
  28 function if_match( req, stat )
  29         local h    = req.headers
  30         local etag = mk_etag( stat )
  31
  32         -- Check for matching resource
  33         if type(h['If-Match']) == "string" then
  34                 for ent in h['If-Match']:gmatch("([^, ]+)") do
  35                         if ( ent == '*' or ent == etag ) and stat ~= nil then
  36                                 return true
  37                         end
  38                 end
  39
  40                 return false, 412
  41         end
  42
  43         return true
  44 end
  45
  46 --- 14.25 / If-Modified-Since
  47 -- Test whether the given message object contains an "If-Modified-Since" header
  48 -- and compare it against the given stat object.
  49 -- @param req   HTTP request message object
  50 -- @param stat  A file.stat object
  51 -- @return              Boolean indicating whether the precondition is ok
  52 -- @return              Alternative status code if the precondition failed
  53 -- @return              Table containing extra HTTP headers if the precondition failed
  54 function if_modified_since( req, stat )
  55         local h = req.headers
  56
  57         -- Compare mtimes
  58         if type(h['If-Modified-Since']) == "string" then
  59                 local since = date.to_unix( h['If-Modified-Since'] )
  60
  61                 if stat == nil or since < stat.mtime then
  62                         return true
  63                 end
  64
  65                 return false, 304, {
  66                         ["ETag"]          = mk_etag( stat );
  67                         ["Date"]          = date.to_http( os.time() );
  68                         ["Last-Modified"] = date.to_http( stat.mtime )
  69                 }
  70         end
  71
  72         return true
  73 end
  74
  75 --- 14.26 / If-None-Match
  76 -- Test whether the given message object contains an "If-None-Match" header and
  77 -- compare it against the given stat object.
  78 -- @param req   HTTP request message object
  79 -- @param stat  A file.stat object
  80 -- @return              Boolean indicating whether the precondition is ok
  81 -- @return              Alternative status code if the precondition failed
  82 -- @return              Table containing extra HTTP headers if the precondition failed
  83 function if_none_match( req, stat )
  84         local h      = req.headers
  85         local etag   = mk_etag( stat )
  86         local method = req.env and req.env.REQUEST_METHOD or "GET"
  87
  88         -- Check for matching resource
  89         if type(h['If-None-Match']) == "string" then
  90                 for ent in h['If-None-Match']:gmatch("([^, ]+)") do
  91                         if ( ent == '*' or ent == etag ) and stat ~= nil then
  92                                 if method == "GET" or method == "HEAD" then
  93                                         return false, 304, {
  94                                                 ["ETag"]          = etag;
  95                                                 ["Date"]          = date.to_http( os.time() );
  96                                                 ["Last-Modified"] = date.to_http( stat.mtime )
  97                                         }
  98                                 else
  99                                         return false, 412
 100                                 end
 101                         end
 102                 end
 103         end
 104
 105         return true
 106 end
 107
 108 --- 14.27 / If-Range
 109 -- The If-Range header is currently not implemented due to the lack of general
 110 -- byte range stuff in luci.http.protocol . This function will always return
 111 -- false, 412 to indicate a failed precondition.
 112 -- @param req   HTTP request message object
 113 -- @param stat  A file.stat object
 114 -- @return              Boolean indicating whether the precondition is ok
 115 -- @return              Alternative status code if the precondition failed
 116 function if_range( req, stat )
 117         -- Sorry, no subranges (yet)
 118         return false, 412
 119 end
 120
 121 --- 14.28 / If-Unmodified-Since
 122 -- Test whether the given message object contains an "If-Unmodified-Since"
 123 -- header and compare it against the given stat object.
 124 -- @param req   HTTP request message object
 125 -- @param stat  A file.stat object
 126 -- @return              Boolean indicating whether the precondition is ok
 127 -- @return              Alternative status code if the precondition failed
 128 function if_unmodified_since( req, stat )
 129         local h = req.headers
 130
 131         -- Compare mtimes
 132         if type(h['If-Unmodified-Since']) == "string" then
 133                 local since = date.to_unix( h['If-Unmodified-Since'] )
 134
 135                 if stat ~= nil and since <= stat.mtime then
 136                         return false, 412
 137                 end
 138         end
 139
 140         return true
 141 end