Add support for SO_ORIGINAL_DST socket option in scala-native

io/jvm-native/src/main/scala/fs2/io/net/SocketOptionPlatform.scala

@@ -28,6 +28,8 @@ import java.lang.{Boolean => JBoolean, Integer => JInt}
 import java.net.{NetworkInterface => JNetworkInterface}
 
 import com.comcast.ip4s.NetworkInterface
+import com.comcast.ip4s.SocketAddress
+import com.comcast.ip4s.IpAddress
 
 private[net] trait SocketOptionCompanionPlatform {
   type Key[A] = JSocketOption[A]
@@ -90,6 +92,11 @@ private[net] trait SocketOptionCompanionPlatform {
   def noDelay(value: Boolean): SocketOption =
     boolean(NoDelay, value)
 
+  val OriginalDestination: Key[SocketAddress[IpAddress]] = new Key[SocketAddress[IpAddress]] {
+    def name() = "SO_ORIGINAL_DST"
+    def `type`() = classOf[SocketAddress[IpAddress]]
+  }
+
   val UnixSocketDeleteIfExists: Key[JBoolean] = new Key[JBoolean] {
     def name() = "FS2_UNIX_DELETE_IF_EXISTS"
     def `type`() = classOf[JBoolean]

io/native/src/main/scala/fs2/io/internal/SocketHelpers.scala

@@ -36,13 +36,14 @@ import com.comcast.ip4s.{
 import java.net.SocketOption
 import java.net.StandardSocketOptions
 import scala.scalanative.meta.LinktimeInfo
-import scala.scalanative.posix.arpa.inet._
 import scala.scalanative.posix.errno.ENOPROTOOPT
 import scala.scalanative.posix.netinet.in.IPPROTO_TCP
 import scala.scalanative.posix.netinet.tcp._
 import scala.scalanative.posix.string._
-import scala.scalanative.posix.sys.socket._
 import scala.scalanative.posix.unistd._
+import scala.scalanative.posix.sys.socket._
+import scala.scalanative.posix.netinet.in._
+import scala.scalanative.posix.arpa.inet._
 import scala.scalanative.unsafe._
 import scala.scalanative.unsigned._
 
@@ -82,7 +83,8 @@ private[io] object SocketHelpers {
         StandardSocketOptions.SO_REUSEADDR,
         StandardSocketOptions.SO_REUSEPORT,
         StandardSocketOptions.SO_KEEPALIVE,
-        StandardSocketOptions.TCP_NODELAY
+        StandardSocketOptions.TCP_NODELAY,
+        fs2.io.net.SocketOption.OriginalDestination
       )
     )
 
@@ -99,6 +101,10 @@ private[io] object SocketHelpers {
       getOptionBool(fd, SO_KEEPALIVE)
     case StandardSocketOptions.TCP_NODELAY =>
       getTcpOptionBool(fd, TCP_NODELAY)
+    case fs2.io.net.SocketOption.OriginalDestination =>
+      // linux kernel option: https://github.com/torvalds/linux/blob/master/include/uapi/linux/netfilter_ipv4.h#L52
+      val SO_ORIGINAL_DST = 80
+      getIpOptSocketAddress(fd, SO_ORIGINAL_DST)
     case _ => Sync[F].pure(None)
   }).asInstanceOf[F[Option[A]]]
 
@@ -114,6 +120,40 @@ private[io] object SocketHelpers {
   def getTcpOptionInt[F[_]: Sync](fd: CInt, option: CInt): F[Option[Int]] =
     getOptionImpl(fd, IPPROTO_TCP /* aka SOL_TCP */, option)
 
+  def getIpOptSocketAddress[F[_]](fd: CInt, option: CInt)(implicit
+      F: Sync[F]
+  ): F[Option[SocketAddress[IpAddress]]] =
+    F.delay {
+      val size = sizeOf[sockaddr_storage]
+      val ptr = stackalloc[Byte](size)
+      val szPtr = stackalloc[UInt]()
+      !szPtr = size.toUInt
+      val ret = guardMask(
+        getsockopt(fd, IPPROTO_IP, option, ptr, szPtr)
+      )(_ == ENOPROTOOPT)
+      if (ret == ENOPROTOOPT) None
+      else {
+        val sockaddr = ptr.asInstanceOf[Ptr[sockaddr_storage]]
+        if (sockaddr._1 == AF_INET) {
+          val dstStr = stackalloc[Byte](INET_ADDRSTRLEN)
+          val addr = ptr.asInstanceOf[Ptr[sockaddr_in]]
+          val addr_in = addr.sin_addr
+          val port = htons(addr.sin_port).toInt
+          inet_ntop(AF_INET, addr_in.toPtr.asInstanceOf[CVoidPtr], dstStr, INET_ADDRSTRLEN.toUInt)
+          SocketAddress.fromString4(s"${fromCString(dstStr)}:$port")
+        } else if (sockaddr._1 == AF_INET6) {
+          val dstStr = stackalloc[Byte](INET6_ADDRSTRLEN)
+          val addr = ptr.asInstanceOf[Ptr[sockaddr_in6]]
+          val addr_in = addr.sin6_addr
+          val port = htons(addr.sin6_port).toInt
+          inet_ntop(AF_INET6, addr_in.toPtr.asInstanceOf[CVoidPtr], dstStr, INET6_ADDRSTRLEN.toUInt)
+          SocketAddress.fromString6(s"${fromCString(dstStr)}:$port")
+        } else {
+          None
+        }
+      }
+    }
+
   def getOptionImpl[F[_]](fd: CInt, level: CInt, option: CInt)(implicit
       F: Sync[F]
   ): F[Option[Int]] =