Instructions' Actions not Available after Reading

[kent-h]

Fixes a bug where actions for instructions were not properly read due to using pass-by-value instead of pass-by-pointer for the action list.

Also fixed a related bug where action lists' padding wasn't read, leading to an off-by-4 read error.

[ybubnov]

@kent-h, nice, could you, please also fix the unit test TestInstructionApplyActions, I believe it should specify a 8-byte padding as in the fix, like this:

tests := []encodingtest.MU{
		{&InstructionApplyActions{
			Actions: Actions{
				&ActionGroup{Group: GroupAll},
				&ActionCopyTTLOut{},
			},
		}, []byte{
			0x00, 0x04, // Instruction type.
			0x00, 0x18, // Instruction length.
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 8-byte padding.

			// Actions.
			0x00, 0x16, // Action group.
			0x00, 0x08, // Action lenght.
			0xff, 0xff, 0xff, 0xfc,
			0x00, 0xb, // Action type.
			0x00, 0x08, // Action lenght.
			0x00, 0x00, 0x00, 0x00, // 4-byte padding.
		}},
	}

Could you, also check that writing of this message puts padding of the appropriate length? Thanks!

[kent-h]

@ybubnov
4 bytes of padding should already be correct. The header.Len-8 is for the 4 byte header + 4 bytes padding.

[ybubnov]

You're right. Ah, I see the reason of test failures, as long as test use the same slice of Actions, on decoding, it appends the same elements twice. The ReadFrom of Actions type should be fixed like this:

diff --git a/ofp/action.go b/ofp/action.go                                                                                                                                                                                                                     
index 191871e..899276e 100644                                                                                                                                                                                                                                  
--- a/ofp/action.go                                                                                                                                                                                                                                            
+++ b/ofp/action.go                                                                                                                                                                                                                                            
@@ -196,6 +196,7 @@ func (a *Actions) WriteTo(w io.Writer) (int64, error) {                                                                                                                                                                                    
 // the list of types that implement Action interface.                                                                                                                                                                                                         
 func (a *Actions) ReadFrom(r io.Reader) (int64, error) {                                                                                                                                                                                                      
        var actionType ActionType                                                                                                                                                                                                                              
+       *a = nil                                                                                                                                                                                                                                               
                                                                                                                                                                                                                                                               
        rm := func() (io.ReaderFrom, error) {                                                                                                                                                                                                                  
                if rm, ok := actionMap[actionType]; ok {

Could you, please, incorporate these changes in your PR?

[kent-h]

Added requested changes.