Parse ip command output to determine broadcast addresses.

1 files changed, 20 insertions, 0 deletions

diff --git a/src/System/Global6.hs b/src/System/Global6.hs
index f70a8547..cc8ed020 100644
--- a/src/System/Global6.hs
+++ b/src/System/Global6.hs
@@ -1,12 +1,14 @@
 module System.Global6 where
 
 import Control.Monad
+import Control.Applicative
 import Data.IP
 import Data.List
 import Data.Maybe
 import Network.Socket
 import System.Process
 import Text.Read
+import System.IO
 
 parseIpAddr :: String -> Maybe IPv6
 parseIpAddr s = do
@@ -26,3 +28,21 @@ global6 = do
     addrs <- lines <$> readProcess "ip" ["-o","-6","addr"] ""
     return $ foldr1 mplus $ map parseIpAddr addrs
 
+everyOther (x:_:xs) = x : everyOther xs
+everyOther xs       = xs
+
+
+-- | Obtain all available IP broadcast addresses (in dotted quad or IPv6 colon
+-- format) as Strings.
+broadcastAddrs :: IO [String]
+broadcastAddrs = parseBroadcastAddrs <$> readProcess "ip" ["-o","addr"] ""
+
+parseBroadcastAddrs :: String -> [String]
+parseBroadcastAddrs ipoutput = brds
+ where
+    brds = mapMaybe getbrd as
+    assoclist ws = zip (everyOther ws) (everyOther $ drop 1 ws)
+    as = map (assoclist . drop 2 . words) $ lines ipoutput
+    getbrd alist = do
+        ip <- lookup "inet" alist <|> lookup "inet6" alist
+        lookup "brd" alist