root / src / Ganeti / Confd / Utils.hs @ ace37e24
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{-| Implementation of the Ganeti confd utilities. |
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This holds a few utility functions that could be useful in both |
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clients and servers. |
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-} |
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{- |
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Copyright (C) 2011, 2012 Google Inc. |
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, but |
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WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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02110-1301, USA. |
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-} |
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module Ganeti.Confd.Utils |
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( getClusterHmac |
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, parseSignedMessage |
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, parseRequest |
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, parseReply |
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, signMessage |
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, getCurrentTime |
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) where |
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import qualified Data.ByteString as B |
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import qualified Text.JSON as J |
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import Ganeti.BasicTypes |
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import Ganeti.Confd.Types |
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import Ganeti.Hash |
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import qualified Ganeti.Constants as C |
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import qualified Ganeti.Path as Path |
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import Ganeti.JSON |
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import Ganeti.Utils |
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-- | Type-adjusted max clock skew constant. |
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maxClockSkew :: Integer |
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maxClockSkew = fromIntegral C.confdMaxClockSkew |
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-- | Returns the HMAC key. |
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getClusterHmac :: IO HashKey |
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getClusterHmac = Path.confdHmacKey >>= fmap B.unpack . B.readFile |
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-- | Parses a signed message. |
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parseSignedMessage :: (J.JSON a) => HashKey -> String |
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-> Result (String, String, a) |
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parseSignedMessage key str = do |
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(SignedMessage hmac msg salt) <- fromJResult "parsing signed message" |
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$ J.decode str |
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parsedMsg <- if verifyMac key (Just salt) msg hmac |
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then fromJResult "parsing message" $ J.decode msg |
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else Bad "HMAC verification failed" |
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return (salt, msg, parsedMsg) |
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-- | Message parsing. This can either result in a good, valid request |
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-- message, or fail in the Result monad. |
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parseRequest :: HashKey -> String -> Integer |
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-> Result (String, ConfdRequest) |
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parseRequest hmac msg curtime = do |
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(salt, origmsg, request) <- parseSignedMessage hmac msg |
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ts <- tryRead "Parsing timestamp" salt::Result Integer |
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if abs (ts - curtime) > maxClockSkew |
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then fail "Too old/too new timestamp or clock skew" |
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else return (origmsg, request) |
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-- | Message parsing. This can either result in a good, valid reply |
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-- message, or fail in the Result monad. |
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-- It also checks that the salt in the message corresponds to the one |
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-- that is expected |
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parseReply :: HashKey -> String -> String -> Result (String, ConfdReply) |
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parseReply hmac msg expSalt = do |
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(salt, origmsg, reply) <- parseSignedMessage hmac msg |
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if salt /= expSalt |
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then fail "The received salt differs from the expected salt" |
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else return (origmsg, reply) |
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-- | Signs a message with a given key and salt. |
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signMessage :: HashKey -> String -> String -> SignedMessage |
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signMessage key salt msg = |
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SignedMessage { signedMsgMsg = msg |
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, signedMsgSalt = salt |
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, signedMsgHmac = hmac |
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} |
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where hmac = computeMac key (Just salt) msg |