net: avoid multiple calling of syscall connect on Unix variants
The previous fix CL 69340044 still leaves a possibility of it.
This CL prevents the kernel, especially DragonFly BSD, from
performing unpredictable asynchronous connection establishment
on stream-based transport layer protocol sockets.
Update #7541
Update #7474
LGTM=jsing
R=jsing
CC=golang-codereviews
https://golang.org/cl/75930043
diff --git a/src/pkg/net/fd_unix.go b/src/pkg/net/fd_unix.go
index 9b0c615..3b67b79 100644
--- a/src/pkg/net/fd_unix.go
+++ b/src/pkg/net/fd_unix.go
@@ -75,51 +75,47 @@
if err := fd.pd.PrepareWrite(); err != nil {
return err
}
- for {
- err := syscall.Connect(fd.sysfd, ra)
- if err == nil || err == syscall.EISCONN {
- break
- }
-
+ switch err := syscall.Connect(fd.sysfd, ra); err {
+ case syscall.EINPROGRESS, syscall.EALREADY, syscall.EINTR:
+ case nil, syscall.EISCONN:
+ return nil
+ case syscall.EINVAL:
// On Solaris we can see EINVAL if the socket has
// already been accepted and closed by the server.
// Treat this as a successful connection--writes to
// the socket will see EOF. For details and a test
// case in C see http://golang.org/issue/6828.
- if runtime.GOOS == "solaris" && err == syscall.EINVAL {
- break
+ if runtime.GOOS == "solaris" {
+ return nil
}
-
- if err != syscall.EINPROGRESS && err != syscall.EALREADY && err != syscall.EINTR {
+ fallthrough
+ default:
+ return err
+ }
+ for {
+ // Performing multiple connect system calls on a
+ // non-blocking socket under Unix variants does not
+ // necessarily result in earlier errors being
+ // returned. Instead, once runtime-integrated network
+ // poller tells us that the socket is ready, get the
+ // SO_ERROR socket option to see if the connection
+ // succeeded or failed. See issue 7474 for further
+ // details.
+ if err := fd.pd.WaitWrite(); err != nil {
return err
}
- if err = fd.pd.WaitWrite(); err != nil {
+ nerr, err := syscall.GetsockoptInt(fd.sysfd, syscall.SOL_SOCKET, syscall.SO_ERROR)
+ if err != nil {
return err
}
-
- // Performing multiple connect system calls on a non-blocking
- // socket under DragonFly BSD does not necessarily result in
- // earlier errors being returned, particularly if we are
- // connecting to localhost. Instead, once netpoll tells us that
- // the socket is ready, get the SO_ERROR socket option to see
- // if the connection succeeded or failed. See issue 7474 for
- // further details. At some point we may want to consider
- // doing the same on other Unixes.
- if runtime.GOOS == "dragonfly" {
- nerr, err := syscall.GetsockoptInt(fd.sysfd, syscall.SOL_SOCKET, syscall.SO_ERROR)
- if err != nil {
- return err
- }
- if nerr == 0 {
- return nil
- }
- err = syscall.Errno(nerr)
- if err != syscall.EINPROGRESS && err != syscall.EALREADY && err != syscall.EINTR {
- return err
- }
+ switch err := syscall.Errno(nerr); err {
+ case syscall.EINPROGRESS, syscall.EALREADY, syscall.EINTR:
+ case syscall.Errno(0), syscall.EISCONN:
+ return nil
+ default:
+ return err
}
}
- return nil
}
func (fd *netFD) destroy() {
