propellor/Propellor/Property/Dns.hs

358 lines
11 KiB
Haskell
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

module Propellor.Property.Dns (
module Propellor.Types.Dns,
primary,
secondary,
secondaryFor,
mkSOA,
writeZoneFile,
nextSerialNumber,
adjustSerialNumber,
serialNumberOffset,
WarningMessage,
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.
mkSOA :: Domain -> SerialNumber -> SOA
mkSOA d sn = SOA
{ sDomain = AbsDomain d
, sSerial = sn
, sRefresh = hours 4
, sRetry = hours 1
, sExpire = 2419200 -- 4 weeks
, sNegativeCacheTTL = hours 8
}
where
hours n = n * 60 * 60
dValue :: BindDomain -> String
dValue (RelDomain d) = d
dValue (AbsDomain d) = d ++ "."
dValue (RootDomain) = "@"
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,
-- and 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 soa ++ map (genRecord zdomain) rs
where
header = com $ "BIND zone file for " ++ zdomain ++ ". Generated by propellor, do not edit."
genRecord :: Domain -> (BindDomain, Record) -> String
genRecord zdomain (domain, record) = intercalate "\t"
[ domainHost zdomain domain
, "IN"
, rField record
, rValue record
]
genSOA :: SOA -> [String]
genSOA soa =
-- "@ IN SOA ns1.example.com. root ("
[ intercalate "\t"
[ dValue RootDomain
, "IN"
, "SOA"
, dValue (sDomain soa)
, "root"
, "("
]
, headerline sSerial "Serial"
, headerline sRefresh "Refresh"
, headerline sRetry "Retry"
, headerline sExpire "Expire"
, headerline sNegativeCacheTTL "Negative Cache TTL"
, inheader ")"
]
where
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 _ RootDomain = "@"
domainHost base (AbsDomain d)
| dotbase `isSuffixOf` d = take (length d - length dotbase) d
| base == d = "@"
| otherwise = d
where
dotbase = '.':base