Enables AMF to accept not-perfect NGAP packets which have not 0 ASN.1…

… PER padding bit. (#2)

* Enables AMF to accept not-perfect NGAP packets which have not 0 ASN.1 PER padding bit.

* Use go build -tags skip_padding_check to switch padding check

Default will check padding if value is 0

Co-authored-by: free5gc-org <free5gc.org@gmail.com>

aper.go

@@ -131,7 +131,12 @@ func (pd *perBitData) parseAlignBits() error {
 		if val, err := pd.getBitsValue(alignBits); err != nil {
 			return err
 		} else if val != 0 {
-			return fmt.Errorf("Align Bit is not zero")
+			if skipPaddingCheck {
+				perTrace(2, "Align Bit is not zero")
+				perTrace(1, perBitLog(uint64(alignBits), pd.byteOffset, pd.bitsOffset, val))
+			} else {
+				return fmt.Errorf("Align Bit is not zero")
+			}
 		}
 	} else if pd.bitsOffset != 0 {
 		pd.bitCarry()

padding_check.go

@@ -0,0 +1,5 @@
+// +build !skip_padding_check
+
+package aper
+
+const skipPaddingCheck bool = false

skip_padding_check.go

@@ -0,0 +1,5 @@
+// +build skip_padding_check
+
+package aper
+
+const skipPaddingCheck bool = true