From c17a9373053cf74967f53570cb21c074fe00587a Mon Sep 17 00:00:00 2001
From: joe <joe@jerkface.net>
Date: Mon, 24 Jul 2017 20:06:42 -0400
Subject: Bootstrap nodes for Mainline rewrite.

---
 Mainline.hs | 46 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 44 insertions(+), 2 deletions(-)

diff --git a/Mainline.hs b/Mainline.hs
index 29f1df80..76e914b3 100644
--- a/Mainline.hs
+++ b/Mainline.hs
@@ -54,6 +54,8 @@ import qualified Network.DHT.Routing      as R
          ;import Network.DHT.Routing      (Info, Timestamp, getTimestamp)
 import Network.QueryResponse
 import Network.Socket
+import System.IO.Error
+import System.IO.Unsafe                   (unsafeInterleaveIO)
 
 newtype NodeId = NodeId ByteString
  deriving (Eq,Ord,Show,ByteArrayAccess, BEncode, Bits, Hashable)
@@ -344,7 +346,7 @@ data Routing = Routing
 
 type MainlineClient = Client String Method TransactionId NodeInfo (Message BValue)
 
-newClient :: SockAddr -> IO MainlineClient
+newClient :: SockAddr -> IO (MainlineClient, Routing)
 newClient addr = do
     udp <- udpTransport addr
     nid <- NodeId <$> getRandomBytes 20
@@ -414,7 +416,7 @@ newClient addr = do
             , clientResponseId    = return
             }
 
-    return client
+    return (client, routing)
 
 defaultHandler :: ByteString -> Handler
 defaultHandler meth = MethodHandler decodePayload errorPayload returnError
@@ -840,3 +842,43 @@ nodeSearch = Search
     , searchNodeAddress = nodeIP &&& nodePort
     , searchQuery = error "searchQuery"
     }
+
+-- | List of bootstrap nodes maintained by different bittorrent
+-- software authors.
+bootstrapNodes :: WantIP -> IO [NodeInfo]
+bootstrapNodes want = unsafeInterleaveIO $ do
+    let wellknowns =
+          [ "router.bittorrent.com:6881" -- by BitTorrent Inc.
+
+            -- doesn't work at the moment (use git blame)  of commit
+          , "dht.transmissionbt.com:6881" -- by Transmission project
+
+          , "router.utorrent.com:6881"
+          ]
+    nss <- forM wellknowns $ \hostAndPort -> do
+        e <- resolve want hostAndPort
+        case e of
+            Left  _        -> return []
+            Right sockaddr -> either (const $ return [])
+                                     (return . (: []))
+                                     $ nodeInfo zeroID sockaddr
+    return $ concat nss
+
+-- | Resolve either a numeric network address or a hostname to a
+-- numeric IP address of the node.
+resolve :: WantIP -> String -> IO (Either IOError SockAddr)
+resolve want hostAndPort = do
+    let hints = defaultHints { addrSocketType = Datagram
+                             , addrFamily = case want of
+                                  Want_IP4 -> AF_INET
+                                  _        -> AF_INET6
+                             }
+        (rport,rhost) = span (/= ':') $ reverse hostAndPort
+        (host,port) = case rhost of
+                        []     -> (hostAndPort, Nothing)
+                        (_:hs) -> (reverse hs, Just (reverse rport))
+    tryIOError $ do
+        -- getAddrInfo throws exception on empty list, so this
+        --  pattern matching never fails.
+        info : _ <- getAddrInfo (Just hints) (Just host) port
+        return $ addrAddress info
-- 
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