propellor/Propellor/Property/Dns.hs

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module Propellor.Property.Dns (
module Propellor.Types.Dns,
primary,
secondary,
secondaryFor,
mkSOA,
rootAddressesFrom,
writeZoneFile,
nextSerialNumber,
adjustSerialNumber,
serialNumberOffset,
genZone,
) where
import Propellor
import Propellor.Types.Dns
import Propellor.Property.File
import Propellor.Types.Attr
import qualified Propellor.Property.Apt as Apt
import qualified Propellor.Property.Service as Service
import Utility.Applicative
import qualified Data.Map as M
import qualified Data.Set as S
import Data.List
-- | Primary dns server for a domain.
--
-- Most of the content of the zone file is configured by setting properties
-- of hosts. For example,
--
-- > host "foo.example.com"
-- > & ipv4 "192.168.1.1"
-- > & alias "mail.exmaple.com"
--
-- Will cause that hostmame and its alias to appear in the zone file,
-- with the configured IP address.
--
-- The [(BindDomain, Record)] list can be used for additional records
-- that cannot be configured elsewhere. For example, it might contain
-- CNAMEs pointing at hosts that propellor does not control.
primary :: [Host] -> Domain -> SOA -> [(BindDomain, Record)] -> Property
primary hosts domain soa rs = withwarnings (check needupdate baseprop)
`requires` servingZones
`onChange` Service.reloaded "bind9"
where
(partialzone, warnings) = genZone hosts domain soa
zone = partialzone { zHosts = zHosts partialzone ++ rs }
zonefile = "/etc/bind/propellor/db." ++ domain
baseprop = Property ("dns primary for " ++ domain)
(makeChange $ writeZoneFile zone zonefile)
(addNamedConf conf)
withwarnings p = adjustProperty p $ \satisfy -> do
mapM_ warningMessage warnings
satisfy
conf = NamedConf
{ confDomain = domain
, confType = Master
, confFile = zonefile
, confMasters = []
, confLines = []
}
needupdate = do
v <- readZonePropellorFile zonefile
return $ case v of
Nothing -> True
Just oldzone ->
-- compare everything except serial
let oldserial = sSerial (zSOA oldzone)
z = zone { zSOA = (zSOA zone) { sSerial = oldserial } }
in z /= oldzone || oldserial < sSerial (zSOA zone)
-- | Secondary dns server for a domain.
--
-- The primary server is determined by looking at the properties of other
-- hosts to find which one is configured as the primary.
--
-- Note that if a host is declared to be a primary and a secondary dns
-- server for the same domain, the primary server config always wins.
secondary :: [Host] -> Domain -> Property
secondary hosts domain = secondaryFor masters hosts domain
where
masters = M.keys $ M.filter ismaster $ hostAttrMap hosts
ismaster attr = case M.lookup domain (_namedconf attr) of
Nothing -> False
Just conf -> confType conf == Master && confDomain conf == domain
-- | This variant is useful if the primary server does not have its DNS
-- configured via propellor.
secondaryFor :: [HostName] -> [Host] -> Domain -> Property
secondaryFor masters hosts domain = pureAttrProperty desc (addNamedConf conf)
`requires` servingZones
where
desc = "dns secondary for " ++ domain
conf = NamedConf
{ confDomain = domain
, confType = Secondary
, confFile = "db." ++ domain
, confMasters = concatMap (\m -> hostAddresses m hosts) masters
, confLines = ["allow-transfer { }"]
}
-- | Rewrites the whole named.conf.local file to serve the zones
-- configured by `primary` and `secondary`, and ensures that bind9 is
-- running.
servingZones :: Property
servingZones = property "serving configured dns zones" go
`requires` Apt.serviceInstalledRunning "bind9"
`onChange` Service.reloaded "bind9"
where
go = do
zs <- getNamedConf
ensureProperty $
hasContent namedConfFile $
concatMap confStanza $ M.elems zs
confStanza :: NamedConf -> [Line]
confStanza c =
[ "// automatically generated by propellor"
, "zone \"" ++ confDomain c ++ "\" {"
, cfgline "type" (if confType c == Master then "master" else "slave")
, cfgline "file" ("\"" ++ confFile c ++ "\"")
] ++
(if null (confMasters c) then [] else mastersblock) ++
(map (\l -> "\t" ++ l ++ ";") (confLines c)) ++
[ "};"
, ""
]
where
cfgline f v = "\t" ++ f ++ " " ++ v ++ ";"
mastersblock =
[ "\tmasters {" ] ++
(map (\ip -> "\t\t" ++ fromIPAddr ip ++ ";") (confMasters c)) ++
[ "\t};" ]
namedConfFile :: FilePath
namedConfFile = "/etc/bind/named.conf.local"
-- | Generates a SOA with some fairly sane numbers in it.
--
-- The Domain is the domain to use in the SOA record. Typically
-- something like ns1.example.com. So, not the domain that this is the SOA
-- record for.
--
-- The SerialNumber can be whatever serial number was used by the domain
-- before propellor started managing it. Or 0 if the domain has only ever
-- been managed by propellor.
--
-- You do not need to increment the SerialNumber when making changes!
-- Propellor will automatically add the number of commits in the git
-- repository to the SerialNumber.
--
-- Handy trick: You don't need to list IPAddrs in the [Record],
-- just make some Host sets its `alias` to the root of domain.
mkSOA :: Domain -> SerialNumber -> [Record] -> SOA
mkSOA d sn rs = SOA
{ sDomain = AbsDomain d
, sSerial = sn
, sRefresh = hours 4
, sRetry = hours 1
, sExpire = 2419200 -- 4 weeks
, sNegativeCacheTTL = hours 8
, sRecord = rs
}
where
hours n = n * 60 * 60
rootAddressesFrom :: [Host] -> HostName -> [Record]
rootAddressesFrom hosts hn = map Address (hostAddresses hn hosts)
dValue :: BindDomain -> String
dValue (RelDomain d) = d
dValue (AbsDomain d) = d ++ "."
dValue (SOADomain) = "@"
rField :: Record -> String
rField (Address (IPv4 _)) = "A"
rField (Address (IPv6 _)) = "AAAA"
rField (CNAME _) = "CNAME"
rField (MX _ _) = "MX"
rField (NS _) = "NS"
rField (TXT _) = "TXT"
rField (SRV _ _ _ _) = "SRV"
rValue :: Record -> String
rValue (Address (IPv4 addr)) = addr
rValue (Address (IPv6 addr)) = addr
rValue (CNAME d) = dValue d
rValue (MX pri d) = show pri ++ " " ++ dValue d
rValue (NS d) = dValue d
rValue (SRV priority weight port target) = unwords
[ show priority
, show weight
, show port
, dValue target
]
rValue (TXT s) = [q] ++ filter (/= q) s ++ [q]
where
q = '"'
-- | Adjusts the serial number of the zone to
--
-- * Always be larger than the serial number in the Zone record.
-- * Always be larger than the passed SerialNumber
nextSerialNumber :: Zone -> SerialNumber -> Zone
nextSerialNumber z serial = adjustSerialNumber z $ \sn -> succ $ max sn serial
adjustSerialNumber :: Zone -> (SerialNumber -> SerialNumber) -> Zone
adjustSerialNumber (Zone d soa l) f = Zone d soa' l
where
soa' = soa { sSerial = f (sSerial soa) }
-- | Count the number of git commits made to the current branch.
serialNumberOffset :: IO SerialNumber
serialNumberOffset = fromIntegral . length . lines
<$> readProcess "git" ["log", "--pretty=%H"]
-- | Write a Zone out to a to a file.
--
-- The serial number in the Zone automatically has the serialNumberOffset
-- added to it. Also, just in case, the old serial number used in the zone
-- file is checked, and if it is somehow larger, its succ is used.
writeZoneFile :: Zone -> FilePath -> IO ()
writeZoneFile z f = do
oldserial <- oldZoneFileSerialNumber f
offset <- serialNumberOffset
let z' = nextSerialNumber
(adjustSerialNumber z (+ offset))
oldserial
createDirectoryIfMissing True (takeDirectory f)
writeFile f (genZoneFile z')
writeZonePropellorFile f z'
-- | Next to the zone file, is a ".propellor" file, which contains
-- the serialized Zone. This saves the bother of parsing
-- the horrible bind zone file format.
zonePropellorFile :: FilePath -> FilePath
zonePropellorFile f = f ++ ".propellor"
oldZoneFileSerialNumber :: FilePath -> IO SerialNumber
oldZoneFileSerialNumber = maybe 0 (sSerial . zSOA) <$$> readZonePropellorFile
writeZonePropellorFile :: FilePath -> Zone -> IO ()
writeZonePropellorFile f z = writeFile (zonePropellorFile f) (show z)
readZonePropellorFile :: FilePath -> IO (Maybe Zone)
readZonePropellorFile f = catchDefaultIO Nothing $
readish <$> readFileStrict (zonePropellorFile f)
-- | Generating a zone file.
genZoneFile :: Zone -> String
genZoneFile (Zone zdomain soa rs) = unlines $
header : genSOA zdomain soa ++ map genr rs
where
header = com $ "BIND zone file for " ++ zdomain ++ ". Generated by propellor, do not edit."
genr (d, r) = genRecord zdomain (Just d, r)
genRecord :: Domain -> (Maybe BindDomain, Record) -> String
genRecord zdomain (mdomain, record) = intercalate "\t"
[ hn
, "IN"
, rField record
, rValue record
]
where
hn = maybe "" (domainHost zdomain) mdomain
genSOA :: Domain -> SOA -> [String]
genSOA zdomain soa =
header ++ map (genRecord zdomain) (zip (repeat Nothing) (sRecord soa))
where
header =
-- "@ IN SOA ns1.example.com. root ("
[ intercalate "\t"
[ dValue SOADomain
, "IN"
, "SOA"
, dValue (sDomain soa)
, "root"
, "("
]
, headerline sSerial "Serial"
, headerline sRefresh "Refresh"
, headerline sRetry "Retry"
, headerline sExpire "Expire"
, headerline sNegativeCacheTTL "Negative Cache TTL"
, inheader ")"
]
headerline r comment = inheader $ show (r soa) ++ "\t\t" ++ com comment
inheader l = "\t\t\t" ++ l
-- | Comment line in a zone file.
com :: String -> String
com s = "; " ++ s
type WarningMessage = String
-- | Generates a Zone for a particular Domain from the DNS properies of all
-- hosts that propellor knows about that are in that Domain.
genZone :: [Host] -> Domain -> SOA -> (Zone, [WarningMessage])
genZone hosts zdomain soa =
let (warnings, zhosts) = partitionEithers $ concat $ map concat
[ map hostips inzdomain
, map hostrecords inzdomain
, map addcnames (M.elems m)
]
in (Zone zdomain soa (nub zhosts), warnings)
where
m = hostAttrMap hosts
-- Known hosts with hostname located in the zone's domain.
inzdomain = M.elems $ M.filterWithKey (\hn _ -> inDomain zdomain $ AbsDomain $ hn) m
-- Each host with a hostname located in the zdomain
-- should have 1 or more IPAddrs in its Attr.
--
-- If a host lacks any IPAddr, it's probably a misconfiguration,
-- so warn.
hostips :: Attr -> [Either WarningMessage (BindDomain, Record)]
hostips attr
| null l = [Left $ "no IP address defined for host " ++ _hostname attr]
| otherwise = map Right l
where
l = zip (repeat $ AbsDomain $ _hostname attr)
(map Address $ getAddresses attr)
-- Any host, whether its hostname is in the zdomain or not,
-- may have cnames which are in the zdomain. The cname may even be
-- the same as the root of the zdomain, which is a nice way to
-- specify IP addresses for a SOA record.
--
-- Add Records for those.. But not actually, usually, cnames!
-- Why not? Well, using cnames doesn't allow doing some things,
-- including MX and round robin DNS, and certianly CNAMES
-- shouldn't be used in SOA records.
--
-- We typically know the host's IPAddrs anyway.
-- So we can just use the IPAddrs.
addcnames :: Attr -> [Either WarningMessage (BindDomain, Record)]
addcnames attr = concatMap gen $ filter (inDomain zdomain) $
mapMaybe getCNAME $ S.toList (_dns attr)
where
gen c = case getAddresses attr of
[] -> [ret (CNAME c)]
l -> map (ret . Address) l
where
ret record = Right (c, record)
-- Adds any other DNS records for a host located in the zdomain.
hostrecords :: Attr -> [Either WarningMessage (BindDomain, Record)]
hostrecords attr = map Right l
where
l = zip (repeat $ AbsDomain $ _hostname attr)
(S.toList $ S.filter (\r -> isNothing (getIPAddr r) && isNothing (getCNAME r)) (_dns attr))
inDomain :: Domain -> BindDomain -> Bool
inDomain domain (AbsDomain d) = domain == d || ('.':domain) `isSuffixOf` d
inDomain _ _ = False -- can't tell, so assume not
-- | Gets the hostname of the second domain, relative to the first domain,
-- suitable for using in a zone file.
domainHost :: Domain -> BindDomain -> String
domainHost _ (RelDomain d) = d
domainHost _ SOADomain = "@"
domainHost base (AbsDomain d)
| dotbase `isSuffixOf` d = take (length d - length dotbase) d
| base == d = "@"
| otherwise = d
where
dotbase = '.':base