Fix build on Plan 9

Changes to go.mod has been left out: requires go-netroute@v0.1.3 and
go-reuseport@master for Plan 9 support.

reuseport.go

@@ -3,41 +3,12 @@ package tcpreuse
 import (
 	"context"
 	"net"
-	"syscall"
 
 	reuseport "github.com/libp2p/go-reuseport"
 )
 
 var fallbackDialer net.Dialer
 
-// reuseErrShouldRetry diagnoses whether to retry after a reuse error.
-// if we failed to bind, we should retry. if bind worked and this is a
-// real dial error (remote end didnt answer) then we should not retry.
-func reuseErrShouldRetry(err error) bool {
-	if err == nil {
-		return false // hey, it worked! no need to retry.
-	}
-
-	// if it's a network timeout error, it's a legitimate failure.
-	if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
-		return false
-	}
-
-	errno, ok := err.(syscall.Errno)
-	if !ok { // not an errno? who knows what this is. retry.
-		return true
-	}
-
-	switch errno {
-	case syscall.EADDRINUSE, syscall.EADDRNOTAVAIL:
-		return true // failure to bind. retry.
-	case syscall.ECONNREFUSED:
-		return false // real dial error
-	default:
-		return true // optimistically default to retry.
-	}
-}
-
 // Dials using reuseport and then redials normally if that fails.
 func reuseDial(ctx context.Context, laddr *net.TCPAddr, network, raddr string) (con net.Conn, err error) {
 	if laddr == nil {

reuseport_plan9.go

+package tcpreuse
+
+import (
+	"net"
+	"os"
+)
+
+// reuseErrShouldRetry diagnoses whether to retry after a reuse error.
+// if we failed to bind, we should retry. if bind worked and this is a
+// real dial error (remote end didnt answer) then we should not retry.
+func reuseErrShouldRetry(err error) bool {
+	if err == nil {
+		return false // hey, it worked! no need to retry.
+	}
+
+	// if it's a network timeout error, it's a legitimate failure.
+	if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
+		return false
+	}
+
+	e, ok := err.(*net.OpError)
+	if !ok {
+		return true
+	}
+
+	e1, ok := e.Err.(*os.PathError)
+	if !ok {
+		return true
+	}
+
+	switch e1.Err.Error() {
+	case "address in use":
+		return true
+	case "connection refused":
+		return false
+	default:
+		return true // optimistically default to retry.
+	}
+}

reuseport_posix.go

+// +build !plan9
+
+package tcpreuse
+
+import (
+	"net"
+	"syscall"
+)
+
+// reuseErrShouldRetry diagnoses whether to retry after a reuse error.
+// if we failed to bind, we should retry. if bind worked and this is a
+// real dial error (remote end didnt answer) then we should not retry.
+func reuseErrShouldRetry(err error) bool {
+	if err == nil {
+		return false // hey, it worked! no need to retry.
+	}
+
+	// if it's a network timeout error, it's a legitimate failure.
+	if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
+		return false
+	}
+
+	errno, ok := err.(syscall.Errno)
+	if !ok { // not an errno? who knows what this is. retry.
+		return true
+	}
+
+	switch errno {
+	case syscall.EADDRINUSE, syscall.EADDRNOTAVAIL:
+		return true // failure to bind. retry.
+	case syscall.ECONNREFUSED:
+		return false // real dial error
+	default:
+		return true // optimistically default to retry.
+	}
+}

reuseport_test.go

+// +build !plan9
+
 package tcpreuse
 
 import (