root / htools / Ganeti / Confd / Server.hs @ 5cefb2b2
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{-# LANGUAGE BangPatterns #-} |
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{-| Implementation of the Ganeti confd server functionality. |
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-} |
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{- |
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Copyright (C) 2011, 2012 Google Inc. |
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|
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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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-} |
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module Ganeti.Confd.Server |
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( main |
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) where |
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|
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import Control.Concurrent |
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import Control.Exception |
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import Control.Monad (forever) |
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import qualified Data.ByteString as B |
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import Data.IORef |
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import Data.List |
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import qualified Data.Map as M |
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import qualified Network.Socket as S |
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import Prelude hiding (catch) |
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import System.Posix.Files |
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import System.Posix.Types |
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import System.Time |
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import qualified Text.JSON as J |
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import System.INotify |
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|
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import Ganeti.Daemon |
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import Ganeti.HTools.JSON |
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import Ganeti.HTools.Types |
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import Ganeti.HTools.Utils |
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import Ganeti.Objects |
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import Ganeti.Confd |
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import Ganeti.Config |
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import Ganeti.Hash |
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import Ganeti.Logging |
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import qualified Ganeti.Constants as C |
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|
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-- * Types and constants definitions |
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|
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-- | What we store as configuration. |
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type CRef = IORef (Result (ConfigData, LinkIpMap)) |
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|
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-- | File stat identifier. |
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type FStat = (EpochTime, FileID, FileOffset) |
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|
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-- | Null 'FStat' value. |
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nullFStat :: FStat |
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nullFStat = (-1, -1, -1) |
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|
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-- | A small type alias for readability. |
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type StatusAnswer = (ConfdReplyStatus, J.JSValue) |
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|
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-- | Reload model data type. |
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data ReloadModel = ReloadNotify -- ^ We are using notifications |
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| ReloadPoll Int -- ^ We are using polling |
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deriving (Eq, Show) |
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|
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-- | Server state data type. |
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data ServerState = ServerState |
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{ reloadModel :: ReloadModel |
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, reloadTime :: Integer |
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, reloadFStat :: FStat |
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} |
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|
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-- | Maximum no-reload poll rounds before reverting to inotify. |
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maxIdlePollRounds :: Int |
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maxIdlePollRounds = 2 |
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|
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-- | Reload timeout in microseconds. |
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configReloadTimeout :: Int |
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configReloadTimeout = C.confdConfigReloadTimeout * 1000000 |
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|
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-- | Ratelimit timeout in microseconds. |
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configReloadRatelimit :: Int |
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configReloadRatelimit = C.confdConfigReloadRatelimit * 1000000 |
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|
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-- | Initial poll round. |
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initialPoll :: ReloadModel |
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initialPoll = ReloadPoll 0 |
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|
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-- | Initial server state. |
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initialState :: ServerState |
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initialState = ServerState initialPoll 0 nullFStat |
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|
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-- | Reload status data type. |
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data ConfigReload = ConfigToDate -- ^ No need to reload |
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| ConfigReloaded -- ^ Configuration reloaded |
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| ConfigIOError -- ^ Error during configuration reload |
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|
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-- | Unknown entry standard response. |
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queryUnknownEntry :: StatusAnswer |
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queryUnknownEntry = (ReplyStatusError, J.showJSON ConfdErrorUnknownEntry) |
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|
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{- not used yet |
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-- | Internal error standard response. |
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queryInternalError :: StatusAnswer |
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queryInternalError = (ReplyStatusError, J.showJSON ConfdErrorInternal) |
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-} |
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|
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-- | Argument error standard response. |
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queryArgumentError :: StatusAnswer |
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queryArgumentError = (ReplyStatusError, J.showJSON ConfdErrorArgument) |
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|
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-- | Returns the current time. |
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getCurrentTime :: IO Integer |
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getCurrentTime = do |
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TOD ctime _ <- getClockTime |
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return ctime |
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|
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-- * Confd base functionality |
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|
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-- | Returns the HMAC key. |
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getClusterHmac :: IO HashKey |
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getClusterHmac = fmap B.unpack $ B.readFile C.confdHmacKey |
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|
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-- | Computes the node role. |
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nodeRole :: ConfigData -> String -> Result ConfdNodeRole |
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nodeRole cfg name = |
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let cmaster = clusterMasterNode . configCluster $ cfg |
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mnode = M.lookup name . configNodes $ cfg |
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in case mnode of |
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Nothing -> Bad "Node not found" |
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Just node | cmaster == name -> Ok NodeRoleMaster |
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| nodeDrained node -> Ok NodeRoleDrained |
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| nodeOffline node -> Ok NodeRoleOffline |
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| nodeMasterCandidate node -> Ok NodeRoleCandidate |
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_ -> Ok NodeRoleRegular |
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|
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-- | Does an instance ip -> instance -> primary node -> primary ip |
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-- transformation. |
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getNodePipByInstanceIp :: ConfigData |
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-> LinkIpMap |
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-> String |
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-> String |
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-> StatusAnswer |
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getNodePipByInstanceIp cfg linkipmap link instip = |
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case M.lookup instip (M.findWithDefault M.empty link linkipmap) of |
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Nothing -> queryUnknownEntry |
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Just instname -> |
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case getInstPrimaryNode cfg instname of |
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Bad _ -> queryUnknownEntry -- either instance or node not found |
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Ok node -> (ReplyStatusOk, J.showJSON (nodePrimaryIp node)) |
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|
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-- | Builds the response to a given query. |
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buildResponse :: (ConfigData, LinkIpMap) -> ConfdRequest -> Result StatusAnswer |
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buildResponse (cfg, _) (ConfdRequest { confdRqType = ReqPing }) = |
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return (ReplyStatusOk, J.showJSON (configVersion cfg)) |
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|
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buildResponse cdata req@(ConfdRequest { confdRqType = ReqClusterMaster }) = |
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case confdRqQuery req of |
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EmptyQuery -> return (ReplyStatusOk, J.showJSON master_name) |
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PlainQuery _ -> return queryArgumentError |
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DictQuery reqq -> do |
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mnode <- getNode cfg master_name |
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let fvals =map (\field -> case field of |
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ReqFieldName -> master_name |
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ReqFieldIp -> clusterMasterIp cluster |
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ReqFieldMNodePip -> nodePrimaryIp mnode |
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) (confdReqQFields reqq) |
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return (ReplyStatusOk, J.showJSON fvals) |
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where master_name = clusterMasterNode cluster |
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cluster = configCluster cfg |
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cfg = fst cdata |
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|
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buildResponse cdata req@(ConfdRequest { confdRqType = ReqNodeRoleByName }) = do |
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node_name <- case confdRqQuery req of |
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PlainQuery str -> return str |
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_ -> fail $ "Invalid query type " ++ show (confdRqQuery req) |
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role <- nodeRole (fst cdata) node_name |
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return (ReplyStatusOk, J.showJSON role) |
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|
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buildResponse cdata (ConfdRequest { confdRqType = ReqNodePipList }) = |
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-- note: we use foldlWithKey because that's present accross more |
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-- versions of the library |
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return (ReplyStatusOk, J.showJSON $ |
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M.foldlWithKey (\accu _ n -> nodePrimaryIp n:accu) [] |
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(configNodes (fst cdata))) |
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|
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buildResponse cdata (ConfdRequest { confdRqType = ReqMcPipList }) = |
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-- note: we use foldlWithKey because that's present accross more |
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-- versions of the library |
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return (ReplyStatusOk, J.showJSON $ |
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M.foldlWithKey (\accu _ n -> if nodeMasterCandidate n |
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then nodePrimaryIp n:accu |
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else accu) [] |
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(configNodes (fst cdata))) |
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|
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buildResponse (cfg, linkipmap) |
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req@(ConfdRequest { confdRqType = ReqInstIpsList }) = do |
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link <- case confdRqQuery req of |
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PlainQuery str -> return str |
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EmptyQuery -> return (getDefaultNicLink cfg) |
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_ -> fail "Invalid query type" |
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return (ReplyStatusOk, J.showJSON $ getInstancesIpByLink linkipmap link) |
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|
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buildResponse cdata (ConfdRequest { confdRqType = ReqNodePipByInstPip |
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, confdRqQuery = DictQuery query}) = |
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let (cfg, linkipmap) = cdata |
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link = maybe (getDefaultNicLink cfg) id (confdReqQLink query) |
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in case confdReqQIp query of |
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Just ip -> return $ getNodePipByInstanceIp cfg linkipmap link ip |
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Nothing -> return (ReplyStatusOk, |
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J.showJSON $ |
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map (getNodePipByInstanceIp cfg linkipmap link) |
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(confdReqQIpList query)) |
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|
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buildResponse _ (ConfdRequest { confdRqType = ReqNodePipByInstPip }) = |
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return queryArgumentError |
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|
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-- | Parses a signed request. |
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parseRequest :: HashKey -> String -> Result (String, String, ConfdRequest) |
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parseRequest key str = do |
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(SignedMessage hmac msg salt) <- fromJResult "parsing request" $ J.decode str |
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req <- 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, req) |
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|
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-- | Creates a ConfdReply from a given answer. |
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serializeResponse :: Result StatusAnswer -> ConfdReply |
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serializeResponse r = |
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let (status, result) = case r of |
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Bad err -> (ReplyStatusError, J.showJSON err) |
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Ok (code, val) -> (code, val) |
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in ConfdReply { confdReplyProtocol = 1 |
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, confdReplyStatus = status |
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, confdReplyAnswer = result |
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, confdReplySerial = 0 } |
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|
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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 |
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|
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-- * Configuration handling |
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|
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-- ** Helper functions |
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|
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-- | Helper function for logging transition into polling mode. |
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moveToPolling :: String -> INotify -> FilePath -> CRef -> MVar ServerState |
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-> IO ReloadModel |
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moveToPolling msg inotify path cref mstate = do |
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logInfo $ "Moving to polling mode: " ++ msg |
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let inotiaction = addNotifier inotify path cref mstate |
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_ <- forkIO $ onReloadTimer inotiaction path cref mstate |
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return initialPoll |
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|
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-- | Helper function for logging transition into inotify mode. |
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moveToNotify :: IO ReloadModel |
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moveToNotify = do |
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logInfo "Moving to inotify mode" |
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return ReloadNotify |
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|
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-- ** Configuration loading |
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|
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-- | (Re)loads the configuration. |
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updateConfig :: FilePath -> CRef -> IO () |
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updateConfig path r = do |
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newcfg <- loadConfig path |
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let !newdata = case newcfg of |
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Ok !cfg -> Ok (cfg, buildLinkIpInstnameMap cfg) |
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Bad _ -> Bad "Cannot load configuration" |
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writeIORef r newdata |
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case newcfg of |
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Ok cfg -> logInfo ("Loaded new config, serial " ++ |
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show (configSerial cfg)) |
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Bad msg -> logError $ "Failed to load config: " ++ msg |
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return () |
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|
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-- | Wrapper over 'updateConfig' that handles IO errors. |
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safeUpdateConfig :: FilePath -> FStat -> CRef -> IO (FStat, ConfigReload) |
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safeUpdateConfig path oldfstat cref = do |
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catch (do |
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nt <- needsReload oldfstat path |
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case nt of |
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Nothing -> return (oldfstat, ConfigToDate) |
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Just nt' -> do |
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updateConfig path cref |
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return (nt', ConfigReloaded) |
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) (\e -> do |
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let msg = "Failure during configuration update: " ++ |
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show (e::IOError) |
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writeIORef cref (Bad msg) |
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return (nullFStat, ConfigIOError) |
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) |
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|
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-- | Computes the file cache data from a FileStatus structure. |
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buildFileStatus :: FileStatus -> FStat |
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buildFileStatus ofs = |
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let modt = modificationTime ofs |
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inum = fileID ofs |
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fsize = fileSize ofs |
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in (modt, inum, fsize) |
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|
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-- | Wrapper over 'buildFileStatus'. This reads the data from the |
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-- filesystem and then builds our cache structure. |
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getFStat :: FilePath -> IO FStat |
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getFStat p = getFileStatus p >>= (return . buildFileStatus) |
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|
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-- | Check if the file needs reloading |
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needsReload :: FStat -> FilePath -> IO (Maybe FStat) |
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needsReload oldstat path = do |
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newstat <- getFStat path |
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return $ if newstat /= oldstat |
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then Just newstat |
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else Nothing |
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|
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-- ** Watcher threads |
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|
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-- $watcher |
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-- We have three threads/functions that can mutate the server state: |
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-- |
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-- 1. the long-interval watcher ('onTimeoutTimer') |
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-- |
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-- 2. the polling watcher ('onReloadTimer') |
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-- |
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-- 3. the inotify event handler ('onInotify') |
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-- |
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-- All of these will mutate the server state under 'modifyMVar' or |
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-- 'modifyMVar_', so that server transitions are more or less |
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-- atomic. The inotify handler remains active during polling mode, but |
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-- checks for polling mode and doesn't do anything in this case (this |
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-- check is needed even if we would unregister the event handler due |
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-- to how events are serialised). |
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|
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-- | Long-interval reload watcher. |
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-- |
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-- This is on top of the inotify-based triggered reload. |
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onTimeoutTimer :: IO Bool -> FilePath -> CRef -> MVar ServerState -> IO () |
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onTimeoutTimer inotiaction path cref state = do |
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threadDelay configReloadTimeout |
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modifyMVar_ state (onTimeoutInner path cref) |
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_ <- inotiaction |
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onTimeoutTimer inotiaction path cref state |
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|
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-- | Inner onTimeout handler. |
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-- |
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-- This mutates the server state under a modifyMVar_ call. It never |
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-- changes the reload model, just does a safety reload and tried to |
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-- re-establish the inotify watcher. |
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onTimeoutInner :: FilePath -> CRef -> ServerState -> IO ServerState |
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onTimeoutInner path cref state = do |
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(newfstat, _) <- safeUpdateConfig path (reloadFStat state) cref |
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return state { reloadFStat = newfstat } |
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|
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-- | Short-interval (polling) reload watcher. |
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-- |
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-- This is only active when we're in polling mode; it will |
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-- automatically exit when it detects that the state has changed to |
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-- notification. |
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onReloadTimer :: IO Bool -> FilePath -> CRef -> MVar ServerState -> IO () |
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onReloadTimer inotiaction path cref state = do |
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continue <- modifyMVar state (onReloadInner inotiaction path cref) |
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if continue |
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then do |
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threadDelay configReloadRatelimit |
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onReloadTimer inotiaction path cref state |
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else -- the inotify watch has been re-established, we can exit |
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return () |
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|
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-- | Inner onReload handler. |
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-- |
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-- This again mutates the state under a modifyMVar call, and also |
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-- returns whether the thread should continue or not. |
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onReloadInner :: IO Bool -> FilePath -> CRef -> ServerState |
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-> IO (ServerState, Bool) |
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onReloadInner _ _ _ state@(ServerState { reloadModel = ReloadNotify } ) = |
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return (state, False) |
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onReloadInner inotiaction path cref |
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state@(ServerState { reloadModel = ReloadPoll pround } ) = do |
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(newfstat, reload) <- safeUpdateConfig path (reloadFStat state) cref |
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let state' = state { reloadFStat = newfstat } |
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-- compute new poll model based on reload data; however, failure to |
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-- re-establish the inotifier means we stay on polling |
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newmode <- case reload of |
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ConfigToDate -> |
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if pround >= maxIdlePollRounds |
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then do -- try to switch to notify |
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result <- inotiaction |
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if result |
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then moveToNotify |
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else return initialPoll |
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else return (ReloadPoll (pround + 1)) |
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_ -> return initialPoll |
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let continue = case newmode of |
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ReloadNotify -> False |
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_ -> True |
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return (state' { reloadModel = newmode }, continue) |
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|
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-- | Setup inotify watcher. |
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-- |
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-- This tries to setup the watch descriptor; in case of any IO errors, |
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-- it will return False. |
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addNotifier :: INotify -> FilePath -> CRef -> MVar ServerState -> IO Bool |
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addNotifier inotify path cref mstate = do |
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catch (addWatch inotify [CloseWrite] path |
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(onInotify inotify path cref mstate) >> return True) |
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(\e -> const (return False) (e::IOError)) |
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|
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-- | Inotify event handler. |
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onInotify :: INotify -> String -> CRef -> MVar ServerState -> Event -> IO () |
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onInotify inotify path cref mstate Ignored = do |
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logInfo "File lost, trying to re-establish notifier" |
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modifyMVar_ mstate $ \state -> do |
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result <- addNotifier inotify path cref mstate |
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(newfstat, _) <- safeUpdateConfig path (reloadFStat state) cref |
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let state' = state { reloadFStat = newfstat } |
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if result |
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then return state' -- keep notify |
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else do |
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mode <- moveToPolling "cannot re-establish inotify watch" inotify |
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path cref mstate |
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return state' { reloadModel = mode } |
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|
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onInotify inotify path cref mstate _ = do |
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modifyMVar_ mstate $ \state -> |
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if (reloadModel state == ReloadNotify) |
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then do |
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ctime <- getCurrentTime |
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(newfstat, _) <- safeUpdateConfig path (reloadFStat state) cref |
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let state' = state { reloadFStat = newfstat, reloadTime = ctime } |
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if abs (reloadTime state - ctime) < |
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fromIntegral C.confdConfigReloadRatelimit |
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then do |
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mode <- moveToPolling "too many reloads" inotify path cref mstate |
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return state' { reloadModel = mode } |
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else return state' |
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else return state |
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|
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-- ** Client input/output handlers |
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|
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-- | Main loop for a given client. |
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responder :: CRef -> S.Socket -> HashKey -> String -> S.SockAddr -> IO () |
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responder cfgref socket hmac msg peer = do |
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ctime <- getCurrentTime |
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case parseMessage hmac msg ctime of |
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Ok (origmsg, rq) -> do |
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logDebug $ "Processing request: " ++ origmsg |
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mcfg <- readIORef cfgref |
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let response = respondInner mcfg hmac rq |
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_ <- S.sendTo socket response peer |
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return () |
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Bad err -> logInfo $ "Failed to parse incoming message: " ++ err |
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return () |
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|
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-- | Mesage parsing. This can either result in a good, valid message, |
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-- or fail in the Result monad. |
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parseMessage :: HashKey -> String -> Integer |
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-> Result (String, ConfdRequest) |
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parseMessage hmac msg curtime = do |
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(salt, origmsg, request) <- parseRequest hmac msg |
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ts <- tryRead "Parsing timestamp" salt::Result Integer |
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if (abs (ts - curtime) > (fromIntegral C.confdMaxClockSkew)) |
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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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|
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-- | Inner helper function for a given client. This generates the |
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-- final encoded message (as a string), ready to be sent out to the |
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-- client. |
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respondInner :: Result (ConfigData, LinkIpMap) -> HashKey |
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-> ConfdRequest -> String |
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respondInner cfg hmac rq = |
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let rsalt = confdRqRsalt rq |
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innermsg = serializeResponse (cfg >>= flip buildResponse rq) |
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innerserialised = J.encodeStrict innermsg |
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outermsg = signMessage hmac rsalt innerserialised |
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outerserialised = confdMagicFourcc ++ J.encodeStrict outermsg |
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in outerserialised |
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|
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-- | Main listener loop. |
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listener :: S.Socket -> HashKey |
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-> (S.Socket -> HashKey -> String -> S.SockAddr -> IO ()) |
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-> IO () |
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listener s hmac resp = do |
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(msg, _, peer) <- S.recvFrom s 4096 |
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if confdMagicFourcc `isPrefixOf` msg |
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then (forkIO $ resp s hmac (drop 4 msg) peer) >> return () |
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else logDebug "Invalid magic code!" >> return () |
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return () |
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|
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-- | Main function. |
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main :: DaemonOptions -> IO () |
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main opts = do |
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parseresult <- parseAddress opts C.defaultConfdPort |
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(af_family, bindaddr) <- exitIfBad "parsing bind address" parseresult |
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s <- S.socket af_family S.Datagram S.defaultProtocol |
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S.bindSocket s bindaddr |
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cref <- newIORef (Bad "Configuration not yet loaded") |
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statemvar <- newMVar initialState |
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hmac <- getClusterHmac |
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-- Inotify setup |
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inotify <- initINotify |
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let inotiaction = addNotifier inotify C.clusterConfFile cref statemvar |
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-- fork the timeout timer |
519 |
_ <- forkIO $ onTimeoutTimer inotiaction C.clusterConfFile cref statemvar |
520 |
-- fork the polling timer |
521 |
_ <- forkIO $ onReloadTimer inotiaction C.clusterConfFile cref statemvar |
522 |
-- and finally enter the responder loop |
523 |
forever $ listener s hmac (responder cref) |