libs/web: rework luci.sauth

	- perform decoding/encoding transparently in read() and write()
	- remove decode() and encode() helpers
	- introduce reap() to kill expired sessions

diff --git a/libs/web/luasrc/sauth.lua b/libs/web/luasrc/sauth.lua
index ef9fa1e3289758d8b7a752bb9d937d83223ad13f..32f172dcda59a0bb5770f9cbaccb0311edd035ca 100644 (file)
--- a/libs/web/luasrc/sauth.lua
+++ b/libs/web/luasrc/sauth.lua
@@ -34,76 +34,68 @@ function prepare()
        end
 end
 
-function encode(t)
-       return luci.util.get_bytecode({
-               user=t.user,
-               token=t.token,
-               secret=t.secret,
-               atime=luci.sys.uptime()
-       })
-end
-
-function decode(blob)
-       local t = loadstring(blob)()
-       return {
-               user = t.user,
-               token = t.token,
-               secret = t.secret,
-               atime = t.atime
-       }
-end
-
---- Read a session and return its content.
--- @param id   Session identifier
--- @return             Session data
 local function _read(id)
        local blob = fs.readfile(sessionpath .. "/" .. id)
        return blob
 end
 
---- Write session data to a session file.
--- @param id   Session identifier
--- @param data Session data
 local function _write(id, data)
        local f = nixio.open(sessionpath .. "/" .. id, "w", 600)
        f:writeall(data)
        f:close()
 end
 
+local function _checkid(id)
+       return not not (id and #id == 32 and id:match("^[a-fA-F0-9]+$"))
+end
+
+--- Write session data to a session file.
+-- @param id   Session identifier
+-- @param data Session data table
 function write(id, data)
        if not sane() then
                prepare()
        end
 
-       if not id or #id == 0 or not id:match("^%w+$") then
-               error("Session ID is not sane!")
-       end
+       assert(_checkid(id), "Security Exception: Session ID is invalid!")
+       assert(type(data) == "table", "Security Exception: Session data invalid!")
+
+       data.atime = luci.sys.uptime()
 
-       _write(id, data)
+       _write(id, luci.util.get_bytecode(data))
 end
 
+--- Read a session and return its content.
+-- @param id   Session identifier
+-- @return             Session data table or nil if the given id is not found
 function read(id)
        if not id or #id == 0 then
-               return
-       end
-       if not id:match("^%w+$") then
-               error("Session ID is not sane!")
+               return nil
        end
+
+       assert(_checkid(id), "Security Exception: Session ID is invalid!")
+
        if not sane(sessionpath .. "/" .. id) then
-               return
+               return nil
        end
 
        local blob = _read(id)
-       if decode(blob).atime + sessiontime < luci.sys.uptime()then
-               fs.unlink(sessionpath .. "/" .. id)
-               return
+       local func = loadstring(blob)
+       setfenv(func, {})
+
+       local sess = func()
+       assert(type(sess) == "table", "Session data invalid!")
+
+       if sess.atime and sess.atime + sessiontime < luci.sys.uptime() then
+               kill(id)
+               return nil
        end
+
        -- refresh atime in session
-       refreshed = encode(decode(blob))
-       write(id, refreshed)
-       return blob
-end
+       write(id, sess)
 
+       return sess
+end
 
 --- Check whether Session environment is sane.
 -- @return Boolean status
@@ -117,8 +109,19 @@ end
 --- Kills a session
 -- @param id   Session identifier
 function kill(id)
-       if not id:match("^%w+$") then
-               error("Session ID is not sane!")
-       end
+       assert(_checkid(id), "Security Exception: Session ID is invalid!")
        fs.unlink(sessionpath .. "/" .. id)
 end
+
+--- Remove all expired session data files
+function reap()
+       if sane() then
+               local id
+               for id in nixio.fs.dir(sessionpath) do
+                       if _checkid(id) then
+                               -- reading the session will kill it if it is expired
+                               read(id)
+                       end
+               end
+       end
+end