use TCP keep-alive instead of SMP protocol PING

simplexmq.cabal

@@ -57,6 +57,7 @@ library
       Simplex.Messaging.Server.StoreLog
       Simplex.Messaging.Transport
       Simplex.Messaging.Transport.Client
+      Simplex.Messaging.Transport.KeepAlive
       Simplex.Messaging.Transport.Server
       Simplex.Messaging.Transport.WebSockets
       Simplex.Messaging.Util

src/Simplex/Messaging/Client.hs

@@ -110,7 +110,7 @@ smpDefaultConfig =
     { qSize = 64,
       defaultTransport = ("5223", transport @TLS),
       tcpTimeout = 4_000_000,
-      smpPing = 30_000_000
+      smpPing = 3_600_000_000 -- 1 hour
     }
 
 data Request = Request

src/Simplex/Messaging/Transport/Client.hs

@@ -20,6 +20,7 @@ import Network.Socket
 import qualified Network.TLS as T
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Transport
+import Simplex.Messaging.Transport.KeepAlive
 import System.IO.Error
 import UnliftIO.Exception (IOException)
 import qualified UnliftIO.Exception as E
@@ -51,6 +52,7 @@ startTCPClient host port clientParams = withSocketsDo $ resolve >>= tryOpen err
     open addr = do
       sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
       connect sock $ addrAddress addr
+      setSocketKeepAlive sock defaultKeepAlive
       ctx <- connectTLS clientParams sock
       getClientConnection ctx
 

src/Simplex/Messaging/Transport/KeepAlive.hs

@@ -0,0 +1,40 @@
+{-# LANGUAGE CApiFFI #-}
+{-# LANGUAGE NamedFieldPuns #-}
+
+module Simplex.Messaging.Transport.KeepAlive where
+
+import Foreign.C (CInt (..))
+import Network.Socket
+
+foreign import capi "sys/socket.h value TCP_KEEPCNT" tcpKeepCnt :: CInt
+
+foreign import capi "sys/socket.h value TCP_KEEPIDLE" tcpKeepIdle :: CInt
+
+foreign import capi "sys/socket.h value TCP_KEEPINTVL" tcpKeepIntvl :: CInt
+
+foreign import capi "sys/socket.h value SOL_TCP" solTcp :: CInt
+
+data KeepAliveOpts = KeepAliveOpts
+  { keepCnt :: Int,
+    keepIdle :: Int,
+    keepIntvl :: Int
+  }
+
+defaultKeepAlive :: KeepAliveOpts
+defaultKeepAlive =
+  KeepAliveOpts
+    { keepCnt = 2,
+      keepIdle = 30,
+      keepIntvl = 15
+    }
+
+setSocketKeepAlive :: Socket -> KeepAliveOpts -> IO ()
+setSocketKeepAlive sock KeepAliveOpts {keepCnt, keepIdle, keepIntvl} = do
+  setSocketOption sock KeepAlive 1
+  putStrLn $ "solTcp: " <> show solTcp
+  putStrLn $ "tcpKeepCnt: " <> show tcpKeepCnt
+  putStrLn $ "tcpKeepIdle: " <> show tcpKeepIdle
+  putStrLn $ "tcpKeepIntvl: " <> show tcpKeepIntvl
+  setSocketOption sock (SockOpt solTcp tcpKeepCnt) keepCnt
+  setSocketOption sock (SockOpt solTcp tcpKeepIdle) keepIdle
+  setSocketOption sock (SockOpt solTcp tcpKeepIntvl) keepIntvl