fixing the Show instance of IPv4-mapped IPv6 address on little endian machines

Author: kazu-yamamoto

Network/Socket/Info.hsc

@@ -448,6 +448,10 @@ unpackBits ((k,v):xs) r
 -----------------------------------------------------------------------------
 -- SockAddr
 
+-- |
+--
+-- >>> SockAddrInet6 80 0 (0,0,0xffff,0x01020304) 0
+-- [::ffff:1.2.3.4]:80
 instance Show SockAddr where
   showsPrec _ (SockAddrUnix str) = showString str
   showsPrec _ (SockAddrInet port ha)
@@ -467,6 +471,11 @@ showHostAddress ip =
   let (u3, u2, u1, u0) = hostAddressToTuple ip in
   foldr1 (.) . intersperse (showChar '.') $ map showInt [u3, u2, u1, u0]
 
+showHostAddress' :: HostAddress -> ShowS
+showHostAddress' ip =
+  let (u3, u2, u1, u0) = hostAddressToTuple' ip in
+  foldr1 (.) . intersperse (showChar '.') $ map showInt [u3, u2, u1, u0]
+
 -- Taken from showIPv6 in Data.IP.Addr.
 
 -- | Show an IPv6 address in the most appropriate notation, based on recommended
@@ -478,10 +487,10 @@ showHostAddress6 :: HostAddress6 -> ShowS
 showHostAddress6 ha6@(a1, a2, a3, a4)
     -- IPv4-Mapped IPv6 Address
     | a1 == 0 && a2 == 0 && a3 == 0xffff =
-      showString "::ffff:" . showHostAddress a4
+      showString "::ffff:" . showHostAddress' a4
     -- IPv4-Compatible IPv6 Address (exclude IPRange ::/112)
     | a1 == 0 && a2 == 0 && a3 == 0 && a4 >= 0x10000 =
-        showString "::" . showHostAddress a4
+        showString "::" . showHostAddress' a4
     -- length of longest run > 1, replace it with "::"
     | end - begin > 1 =
         showFields prefix . showString "::" . showFields suffix

Network/Socket/Types.hsc

@@ -57,6 +57,7 @@ module Network.Socket.Types (
     , isSupportedSockAddr
     , HostAddress
     , hostAddressToTuple
+    , hostAddressToTuple'
     , tupleToHostAddress
     , HostAddress6
     , hostAddress6ToTuple
@@ -1231,6 +1232,11 @@ hostAddressToTuple ha' =
         byte i = fromIntegral (ha `shiftR` i) :: Word8
     in (byte 24, byte 16, byte 8, byte 0)
 
+hostAddressToTuple' :: HostAddress -> (Word8, Word8, Word8, Word8)
+hostAddressToTuple' ha =
+    let byte i = fromIntegral (ha `shiftR` i) :: Word8
+    in (byte 24, byte 16, byte 8, byte 0)
+
 -- | Converts IPv4 quadruple to 'HostAddress'.
 tupleToHostAddress :: (Word8, Word8, Word8, Word8) -> HostAddress
 tupleToHostAddress (b3, b2, b1, b0) =