net: add FlagRunning to exactly reflect the states of an interface.

Correctly set this flag while parsing the syscall result.

The FlagUp flag can not distinguish the following situations:
1. interface is plugged, automatically up, and in running(UP) state
2. interface is not plugged, administratively or manually set to up,
but in DOWN state

So, We can't distinguish the state of a NIC by the FlagUp flag alone.

Fixes #53482

Change-Id: I43796bea1a7f72d1fddfef914efe603c81995e1b
GitHub-Last-Rev: 686b5d888e97e9b90cf36ac0c15943eb97e125d4
GitHub-Pull-Request: golang/go#53484
Reviewed-on: https://go-review.googlesource.com/c/go/+/413454
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ryan Schuster <shuey19831@gmail.com>
Reviewed-by: Jianwei Mao <maojianwei2020@gmail.com>
Reviewed-by: Damien Neil <dneil@google.com>

7 files changed, 18 insertions, 3 deletions

diff --git a/src/net/interface.go b/src/net/interface.go
index 0e5d3202c9..e1c9a2e2ff 100644
--- a/src/net/interface.go
+++ b/src/net/interface.go
@@ -39,11 +39,12 @@ type Interface struct {
 type Flags uint
 
 const (
-	FlagUp           Flags = 1 << iota // interface is up
+	FlagUp           Flags = 1 << iota // interface is administratively up
 	FlagBroadcast                      // interface supports broadcast access capability
 	FlagLoopback                       // interface is a loopback interface
 	FlagPointToPoint                   // interface belongs to a point-to-point link
 	FlagMulticast                      // interface supports multicast access capability
+	FlagRunning                        // interface is in running state
 )
 
 var flagNames = []string{
@@ -52,6 +53,7 @@ var flagNames = []string{
 	"loopback",
 	"pointtopoint",
 	"multicast",
+	"running",
 }
 
 func (f Flags) String() string {
diff --git a/src/net/interface_aix.go b/src/net/interface_aix.go
index 7ad45d1175..f2e967b1e8 100644
--- a/src/net/interface_aix.go
+++ b/src/net/interface_aix.go
@@ -101,6 +101,9 @@ func linkFlags(rawFlags int32) Flags {
 	if rawFlags&syscall.IFF_UP != 0 {
 		f |= FlagUp
 	}
+	if rawFlags&syscall.IFF_RUNNING != 0 {
+		f |= FlagRunning
+	}
 	if rawFlags&syscall.IFF_BROADCAST != 0 {
 		f |= FlagBroadcast
 	}
diff --git a/src/net/interface_bsd.go b/src/net/interface_bsd.go
index db7bc756d8..9b2b42addb 100644
--- a/src/net/interface_bsd.go
+++ b/src/net/interface_bsd.go
@@ -59,6 +59,9 @@ func linkFlags(rawFlags int) Flags {
 	if rawFlags&syscall.IFF_UP != 0 {
 		f |= FlagUp
 	}
+	if rawFlags&syscall.IFF_RUNNING != 0 {
+		f |= FlagRunning
+	}
 	if rawFlags&syscall.IFF_BROADCAST != 0 {
 		f |= FlagBroadcast
 	}
diff --git a/src/net/interface_linux.go b/src/net/interface_linux.go
index 441ab2f880..9112ecc854 100644
--- a/src/net/interface_linux.go
+++ b/src/net/interface_linux.go
@@ -99,6 +99,9 @@ func linkFlags(rawFlags uint32) Flags {
 	if rawFlags&syscall.IFF_UP != 0 {
 		f |= FlagUp
 	}
+	if rawFlags&syscall.IFF_RUNNING != 0 {
+		f |= FlagRunning
+	}
 	if rawFlags&syscall.IFF_BROADCAST != 0 {
 		f |= FlagBroadcast
 	}
diff --git a/src/net/interface_plan9.go b/src/net/interface_plan9.go
index 957975c265..92b2eed259 100644
--- a/src/net/interface_plan9.go
+++ b/src/net/interface_plan9.go
@@ -95,9 +95,9 @@ func readInterface(i int) (*Interface, error) {
 			}
 		}
 
-		ifc.Flags = FlagUp | FlagBroadcast | FlagMulticast
+		ifc.Flags = FlagUp | FlagRunning | FlagBroadcast | FlagMulticast
 	} else {
-		ifc.Flags = FlagUp | FlagMulticast | FlagLoopback
+		ifc.Flags = FlagUp | FlagRunning | FlagMulticast | FlagLoopback
 	}
 
 	return ifc, nil
diff --git a/src/net/interface_solaris.go b/src/net/interface_solaris.go
index f8d1571b90..32f503f45b 100644
--- a/src/net/interface_solaris.go
+++ b/src/net/interface_solaris.go
@@ -37,6 +37,9 @@ func linkFlags(rawFlags int) Flags {
 	if rawFlags&syscall.IFF_UP != 0 {
 		f |= FlagUp
 	}
+	if rawFlags&syscall.IFF_RUNNING != 0 {
+		f |= FlagRunning
+	}
 	if rawFlags&syscall.IFF_BROADCAST != 0 {
 		f |= FlagBroadcast
 	}
diff --git a/src/net/interface_windows.go b/src/net/interface_windows.go
index 30e90b83c1..22a1312849 100644
--- a/src/net/interface_windows.go
+++ b/src/net/interface_windows.go
@@ -62,6 +62,7 @@ func interfaceTable(ifindex int) ([]Interface, error) {
 			}
 			if aa.OperStatus == windows.IfOperStatusUp {
 				ifi.Flags |= FlagUp
+				ifi.Flags |= FlagRunning
 			}
 			// For now we need to infer link-layer service
 			// capabilities from media types.