2 files changed, 118 insertions, 1 deletions
diff --git a/src/Main.hs b/src/Main.hs
index 65ae4a0..4c9b1fc 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,4 +1,96 @@
 module Main where
 
+import Control.Concurrent
+import Control.Concurrent.STM
+import Control.Monad
+
+import System.Environment
+import System.IO
+import System.IO.Error
+import System.Process
+
+data Network = Network
+    { netNodes :: MVar [(Int, Node)]
+    }
+
+data Node = Node
+    { nodeNetwork :: Network
+    , nodeName :: String
+    }
+
+data Process = Process
+    { procHandle :: ProcessHandle
+    , procNode :: Node
+    , procStdin :: Handle
+    , procOutput :: TVar [String]
+    }
+
+initNetwork :: IO Network
+initNetwork = do
+    callCommand "ip link add name br0 type bridge"
+    callCommand "ip addr add 192.168.0.1/24 broadcast 192.168.0.255 dev br0"
+    callCommand "ip link set dev br0 up"
+    callCommand "ip link set dev lo up"
+    Network <$> newMVar []
+
+getNode :: Network -> Int -> IO Node
+getNode net idx = (lookup idx <$> readMVar (netNodes net)) >>= \case
+    Just node -> return node
+    _ -> do
+        let name = "node" ++ show idx
+            node = Node { nodeNetwork = net
+                        , nodeName = name
+                        }
+        callCommand $ "ip netns add \""++ name ++ "\""
+        callCommand $ "ip link add \"veth" ++ show idx ++ ".0\" type veth peer name \"veth" ++ show idx ++ ".1\" netns \"" ++ name ++ "\""
+        callCommand $ "ip link set dev \"veth" ++ show idx ++ ".0\" master br0 up"
+        callOn node $ "ip addr add 192.168.0." ++ show (10 + idx) ++ "/24 broadcast 192.168.0.255 dev \"veth" ++ show idx ++ ".1\""
+        callOn node $ "ip link set dev \"veth" ++ show idx ++ ".1\" up"
+        callOn node $ "ip link set dev lo up"
+        modifyMVar_ (netNodes net) $ return . ((idx, node):)
+        return node
+
+callOn :: Node -> String -> IO ()
+callOn node cmd = callCommand $ "ip netns exec \"" ++ nodeName node ++ "\" " ++ cmd
+
+spawnOn :: Node -> String -> IO Process
+spawnOn node cmd = do
+    (Just hin, Just hout, Just herr, handle) <- createProcess (shell $ "ip netns exec \"" ++ nodeName node ++ "\" " ++ cmd)
+        { std_in = CreatePipe, std_out = CreatePipe, std_err = CreatePipe }
+    out <- newTVarIO []
+
+    let readingLoop :: Handle -> (String -> IO ()) -> IO ()
+        readingLoop h act =
+            tryIOError (hGetLine h) >>= \case
+                Left err
+                    | isEOFError err -> return ()
+                    | otherwise -> putStrLn $ "\ESC[31m" ++ nodeName node ++ "!!> IO error: " ++ show err ++ "\ESC[0m"
+                Right line -> do
+                    act line
+                    readingLoop h act
+
+    void $ forkIO $ readingLoop hout $ \line -> do
+        putStrLn $ nodeName node ++ "> " ++ line
+        atomically $ modifyTVar out (++[line])
+    void $ forkIO $ readingLoop herr $ \line -> do
+        putStrLn $ "\ESC[31m" ++ nodeName node ++ "!> " ++ line ++ "\ESC[0m"
+
+    return Process
+        { procHandle = handle
+        , procNode = node
+        , procStdin = hin
+        , procOutput = out
+        }
+
 main :: IO ()
-main = putStrLn "Hello, Haskell!"
+main = do
+    [tool] <- getArgs
+
+    net <- initNetwork
+    node1 <- getNode net 1
+    node2 <- getNode net 2
+
+    p1 <- spawnOn node1 tool
+    p2 <- spawnOn node2 tool
+
+    void $ return (p1, p2)
diff --git a/src/Wrapper.hs b/src/Wrapper.hs
new file mode 100644
index 0000000..c97d242
--- /dev/null
+++ b/src/Wrapper.hs
@@ -0,0 +1,25 @@
+module Main where
+
+import System.Environment
+import System.FilePath
+import System.Linux.Namespaces
+import System.Posix.Process
+import System.Posix.User
+import System.Process
+
+main :: IO ()
+main = do
+    -- we must get uid/gid before unshare
+    uid <- getEffectiveUserID
+    gid <- getEffectiveGroupID
+
+    unshare [User, Network, Mount]
+    writeUserMappings Nothing [UserMapping 0 uid 1]
+    writeGroupMappings Nothing [GroupMapping 0 gid 1] True
+
+    -- needed for creating /run/netns
+    callCommand "mount -t tmpfs tmpfs /run"
+
+    path <- getExecutablePath
+    args <- getArgs
+    executeFile (takeDirectory path </> "../../../erebos-tester-core/build/erebos-tester-core/erebos-tester-core") False args Nothing