From a76fa89bf612f39a053390dfe1c78ba1f9331bd8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Sat, 25 Mar 2023 22:24:04 +0100
Subject: Network refactoring with explicit prefixes

---
 src/Network.hs | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 96 insertions(+), 4 deletions(-)

(limited to 'src/Network.hs')

diff --git a/src/Network.hs b/src/Network.hs
index 5b386c8..29621fc 100644
--- a/src/Network.hs
+++ b/src/Network.hs
@@ -1,23 +1,46 @@
 module Network (
+    Internet(..),
     Network(..),
     Node(..),
     NodeName(..), textNodeName, unpackNodeName,
     nextNodeName,
+
+    HasNetns(..),
+    callOn,
+
+    newInternet, delInternet,
+    newNode,
 ) where
 
 import Control.Arrow
-import Control.Concurrent
+import Control.Concurrent.STM
+import Control.Monad
+import Control.Monad.IO.Class
 
 import Data.Text (Text)
 import Data.Text qualified as T
+import Data.Word
+
+import System.Directory
+import System.FilePath
+import System.Process
 
 import Test
 
+data Internet = Internet
+    { inetDir :: FilePath
+    , inetRoot :: Network
+    }
+
 data Network = Network
-    { netNodes :: MVar [Node]
+    { netPrefix :: [Word8]
+    , netNodes :: TVar [Node]
     , netDir :: FilePath
     }
 
+textNetworkName :: Network -> Text
+textNetworkName n = T.intercalate "_" (map (T.pack . show) (netPrefix n))
+
 data Node = Node
     { nodeName :: NodeName
     , nodeIp :: Text
@@ -43,10 +66,18 @@ nextNodeName (VarName tname) = go 0
                                   | otherwise       = go n ns
 
 
+class HasNetns a where netnsName :: a -> Text
+instance HasNetns Network where netnsName n = "s" <> textNetworkName n
+instance HasNetns Node where netnsName n = netnsName (nodeNetwork n) <> ":" <> textNodeName (nodeName n)
+
+callOn :: HasNetns a => a -> Text -> IO ()
+callOn n cmd = callCommand $ T.unpack $ "ip netns exec \"" <> netnsName n <> "\" " <> cmd
+
+
 instance ExprType Network where
     textExprType _ = T.pack "network"
-    textExprValue _ = T.pack "s:0"
-    emptyVarValue = Network undefined undefined
+    textExprValue n = "s:" <> textNetworkName n
+    emptyVarValue = Network [] undefined undefined
 
 instance ExprType Node where
     textExprType _ = T.pack "node"
@@ -56,3 +87,64 @@ instance ExprType Node where
     recordMembers = map (first T.pack)
         [ ("ip", RecordSelector $ nodeIp)
         ]
+
+
+makeIpAddress :: [Word8] -> Word8 -> Text
+makeIpAddress prefix num = T.intercalate "." $ map (T.pack . show) $ prefix ++ replicate (3 - length prefix) 0 ++ [num]
+
+newInternet :: MonadIO m => FilePath -> m Internet
+newInternet dir = do
+    inet <- liftIO $ atomically $ do
+        Internet
+            <$> pure dir
+            <*> newNetwork [1] dir
+    initNetwork $ inetRoot inet
+    return inet
+
+delInternet :: MonadIO m => Internet -> m ()
+delInternet _ = liftIO $ do
+    callCommand $ "ip -all netns delete"
+
+newNetwork :: [Word8] -> FilePath -> STM Network
+newNetwork prefix dir = do
+    Network
+        <$> pure prefix
+        <*> newTVar []
+        <*> pure dir
+
+initNetwork :: MonadIO m => Network -> m ()
+initNetwork net = liftIO $ do
+    callCommand $ T.unpack $ "ip netns add \"" <> netnsName net <> "\""
+    callOn net $ "ip link add name br0 type bridge"
+    callOn net $ "ip addr add " <> makeIpAddress (netPrefix net) 1 <> " broadcast " <> makeIpAddress (netPrefix net) 255 <> " dev br0"
+    callOn net $ "ip link set dev br0 up"
+    callOn net $ "ip link set dev lo up"
+
+newNode :: MonadIO m => Network -> VarName -> m Node
+newNode net vname = liftIO $ do
+    node <- atomically $ do
+        nodes <- readTVar (netNodes net)
+        let nname = nextNodeName vname $ map nodeName nodes
+            node = Node { nodeName = nname
+                        , nodeIp = makeIpAddress (netPrefix net) (fromIntegral $ 2 + length nodes)
+                        , nodeNetwork = net
+                        , nodeDir = netDir net </> ("node_" ++ unpackNodeName nname)
+                        }
+        writeTVar (netNodes net) (node : nodes)
+        return node
+
+    let name = textNodeName $ nodeName node
+        dir = nodeDir node
+
+    exists <- doesPathExist dir
+    when exists $ ioError $ userError $ dir ++ " exists"
+    createDirectoryIfMissing True dir
+
+    callCommand $ T.unpack $ "ip netns add \"" <> netnsName node <> "\""
+    callOn net  $ "ip link add \"veth_" <> name <> "\" type veth peer name veth0 netns \"" <> netnsName node <> "\""
+    callOn net  $ "ip link set dev \"veth_" <> name <> "\" master br0 up"
+    callOn node $ "ip addr add " <> nodeIp node <> "/24 broadcast " <> makeIpAddress (netPrefix net) 255 <> " dev veth0"
+    callOn node $ "ip link set dev veth0 up"
+    callOn node $ "ip link set dev lo up"
+
+    return node
-- 
cgit v1.2.3