Follow golangci advices

gtpv1/ie/uli.go

@@ -99,8 +99,7 @@ func (i *IE) CGI() (uint16, error) {
 		return 0, io.ErrUnexpectedEOF
 	}
 
-	switch i.Payload[0] {
-	case locTypeCGI:
+	if i.Payload[0] == locTypeCGI {
 		if len(i.Payload) < 8 {
 			return 0, io.ErrUnexpectedEOF
 		}
@@ -125,8 +124,7 @@ func (i *IE) SAC() (uint16, error) {
 		return 0, io.ErrUnexpectedEOF
 	}
 
-	switch i.Payload[0] {
-	case locTypeSAI:
+	if i.Payload[0] == locTypeSAI {
 		if len(i.Payload) < 8 {
 			return 0, io.ErrUnexpectedEOF
 		}

gtpv1/message/create-pdp-context-req.go

@@ -1,4 +1,4 @@
-// Copyright 2019-2024 go-gtp authors. All rights reserved.
+// Copyright 2019-2023 go-gtp authors. All rights reserved.
 // Use of this source code is governed by a MIT-style license that can be
 // found in the LICENSE file.
 
@@ -79,11 +79,13 @@ func NewCreatePDPContextRequest(teid uint32, seq uint16, ies ...*ie.IE) *CreateP
 		case ie.NSAPI:
 			if c.NSAPI == nil {
 				c.NSAPI = i
-			} else if c.LinkedNSAPI == nil {
+				continue
+			}
+			if c.LinkedNSAPI == nil {
 				c.LinkedNSAPI = i
-			} else {
-				c.AdditionalIEs = append(c.AdditionalIEs, i)
+				continue
 			}
+			c.AdditionalIEs = append(c.AdditionalIEs, i)
 		case ie.ChargingCharacteristics:
 			c.ChargingCharacteristics = i
 		case ie.TraceReference:
@@ -99,11 +101,13 @@ func NewCreatePDPContextRequest(teid uint32, seq uint16, ies ...*ie.IE) *CreateP
 		case ie.GSNAddress:
 			if c.SGSNAddressForSignalling == nil {
 				c.SGSNAddressForSignalling = i
-			} else if c.SGSNAddressForUserTraffic == nil {
+				continue
+			}
+			if c.SGSNAddressForUserTraffic == nil {
 				c.SGSNAddressForUserTraffic = i
-			} else {
-				c.AdditionalIEs = append(c.AdditionalIEs, i)
+				continue
 			}
+			c.AdditionalIEs = append(c.AdditionalIEs, i)
 		case ie.MSISDN:
 			c.MSISDN = i
 		case ie.QoSProfile:
@@ -471,11 +475,13 @@ func (c *CreatePDPContextRequest) UnmarshalBinary(b []byte) error {
 		case ie.NSAPI:
 			if c.NSAPI == nil {
 				c.NSAPI = i
-			} else if c.LinkedNSAPI == nil {
+				continue
+			}
+			if c.LinkedNSAPI == nil {
 				c.LinkedNSAPI = i
-			} else {
-				c.AdditionalIEs = append(c.AdditionalIEs, i)
+				continue
 			}
+			c.AdditionalIEs = append(c.AdditionalIEs, i)
 		case ie.ChargingCharacteristics:
 			c.ChargingCharacteristics = i
 		case ie.TraceReference:
@@ -491,11 +497,13 @@ func (c *CreatePDPContextRequest) UnmarshalBinary(b []byte) error {
 		case ie.GSNAddress:
 			if c.SGSNAddressForSignalling == nil {
 				c.SGSNAddressForSignalling = i
-			} else if c.SGSNAddressForUserTraffic == nil {
+				continue
+			}
+			if c.SGSNAddressForUserTraffic == nil {
 				c.SGSNAddressForUserTraffic = i
-			} else {
-				c.AdditionalIEs = append(c.AdditionalIEs, i)
+				continue
 			}
+			c.AdditionalIEs = append(c.AdditionalIEs, i)
 		case ie.MSISDN:
 			c.MSISDN = i
 		case ie.QoSProfile:

gtpv1/message/create-pdp-context-res.go

@@ -73,13 +73,17 @@ func NewCreatePDPContextResponse(teid uint32, seq uint16, ies ...*ie.IE) *Create
 		case ie.GSNAddress:
 			if c.GGSNAddressForCPlane == nil {
 				c.GGSNAddressForCPlane = i
-			} else if c.GGSNAddressForUserTraffic == nil {
+				continue
+			}
+			if c.GGSNAddressForUserTraffic == nil {
 				c.GGSNAddressForUserTraffic = i
-			} else if c.AltGGSNAddressForCPlane == nil {
+				continue
+			}
+			if c.AltGGSNAddressForCPlane == nil {
 				c.AltGGSNAddressForCPlane = i
-			} else if c.AltGGSNAddressForUserTraffic == nil {
-				c.AltGGSNAddressForUserTraffic = i
+				continue
 			}
+			c.AltGGSNAddressForUserTraffic = i
 		case ie.QoSProfile:
 			c.QoSProfile = i
 		case ie.ChargingGatewayAddress:
@@ -365,21 +369,25 @@ func (c *CreatePDPContextResponse) UnmarshalBinary(b []byte) error {
 		case ie.GSNAddress:
 			if c.GGSNAddressForCPlane == nil {
 				c.GGSNAddressForCPlane = i
-			} else if c.GGSNAddressForUserTraffic == nil {
+				continue
+			}
+			if c.GGSNAddressForUserTraffic == nil {
 				c.GGSNAddressForUserTraffic = i
-			} else if c.AltGGSNAddressForCPlane == nil {
+				continue
+			}
+			if c.AltGGSNAddressForCPlane == nil {
 				c.AltGGSNAddressForCPlane = i
-			} else if c.AltGGSNAddressForUserTraffic == nil {
-				c.AltGGSNAddressForUserTraffic = i
+				continue
 			}
+			c.AltGGSNAddressForUserTraffic = i
 		case ie.QoSProfile:
 			c.QoSProfile = i
 		case ie.ChargingGatewayAddress:
 			if c.ChargingGatewayAddress == nil {
 				c.ChargingGatewayAddress = i
-			} else if c.AltChargingGatewayAddress == nil {
-				c.AltChargingGatewayAddress = i
+				continue
 			}
+			c.AltChargingGatewayAddress = i
 		case ie.CommonFlags:
 			c.CommonFlags = i
 		case ie.APNRestriction:

gtpv1/message/update-pdp-context-req.go

@@ -77,13 +77,17 @@ func NewUpdatePDPContextRequest(teid uint32, seq uint16, ies ...*ie.IE) *UpdateP
 		case ie.GSNAddress:
 			if u.SGSNAddressForCPlane == nil {
 				u.SGSNAddressForCPlane = i
-			} else if u.SGSNAddressForUserTraffic == nil {
+				continue
+			}
+			if u.SGSNAddressForUserTraffic == nil {
 				u.SGSNAddressForUserTraffic = i
-			} else if u.AlternativeSGSNAddressForCPlane == nil {
+				continue
+			}
+			if u.AlternativeSGSNAddressForCPlane == nil {
 				u.AlternativeSGSNAddressForCPlane = i
-			} else if u.AlternativeSGSNAddressForUserTraffic == nil {
-				u.AlternativeSGSNAddressForUserTraffic = i
+				continue
 			}
+			u.AlternativeSGSNAddressForUserTraffic = i
 		case ie.QoSProfile:
 			u.QoSProfile = i
 		case ie.TrafficFlowTemplate:
@@ -399,13 +403,17 @@ func (u *UpdatePDPContextRequest) UnmarshalBinary(b []byte) error {
 		case ie.GSNAddress:
 			if u.SGSNAddressForCPlane == nil {
 				u.SGSNAddressForCPlane = i
-			} else if u.SGSNAddressForUserTraffic == nil {
+				continue
+			}
+			if u.SGSNAddressForUserTraffic == nil {
 				u.SGSNAddressForUserTraffic = i
-			} else if u.AlternativeSGSNAddressForCPlane == nil {
+				continue
+			}
+			if u.AlternativeSGSNAddressForCPlane == nil {
 				u.AlternativeSGSNAddressForCPlane = i
-			} else if u.AlternativeSGSNAddressForUserTraffic == nil {
-				u.AlternativeSGSNAddressForUserTraffic = i
+				continue
 			}
+			u.AlternativeSGSNAddressForUserTraffic = i
 		case ie.QoSProfile:
 			u.QoSProfile = i
 		case ie.TrafficFlowTemplate:

gtpv1/message/update-pdp-context-res.go

@@ -61,13 +61,17 @@ func NewUpdatePDPContextResponse(teid uint32, seq uint16, ies ...*ie.IE) *Update
 		case ie.GSNAddress:
 			if u.GGSNAddressForCPlane == nil {
 				u.GGSNAddressForCPlane = i
-			} else if u.GGSNAddressForUserTraffic == nil {
+				continue
+			}
+			if u.GGSNAddressForUserTraffic == nil {
 				u.GGSNAddressForUserTraffic = i
-			} else if u.AltGGSNAddressForCPlane == nil {
+				continue
+			}
+			if u.AltGGSNAddressForCPlane == nil {
 				u.AltGGSNAddressForCPlane = i
-			} else if u.AltGGSNAddressForUserTraffic == nil {
-				u.AltGGSNAddressForUserTraffic = i
+				continue
 			}
+			u.AltGGSNAddressForUserTraffic = i
 		case ie.QoSProfile:
 			u.QoSProfile = i
 		case ie.ChargingGatewayAddress:
@@ -305,13 +309,17 @@ func (u *UpdatePDPContextResponse) UnmarshalBinary(b []byte) error {
 		case ie.GSNAddress:
 			if u.GGSNAddressForCPlane == nil {
 				u.GGSNAddressForCPlane = i
-			} else if u.GGSNAddressForUserTraffic == nil {
+				continue
+			}
+			if u.GGSNAddressForUserTraffic == nil {
 				u.GGSNAddressForUserTraffic = i
-			} else if u.AltGGSNAddressForCPlane == nil {
+				continue
+			}
+			if u.AltGGSNAddressForCPlane == nil {
 				u.AltGGSNAddressForCPlane = i
-			} else if u.AltGGSNAddressForUserTraffic == nil {
-				u.AltGGSNAddressForUserTraffic = i
+				continue
 			}
+			u.AltGGSNAddressForUserTraffic = i
 		case ie.QoSProfile:
 			u.QoSProfile = i
 		case ie.ChargingGatewayAddress:

gtpv1/u-conn.go

@@ -197,9 +197,8 @@ func newPktConn(laddr net.Addr) (pktConn, error) {
 			udpConn:    pktC.(*net.UDPConn),
 			PacketConn: ipv6.NewPacketConn(pktC),
 		}, nil
-	} else {
-		return nil, fmt.Errorf("laddr must refer to an IP address")
 	}
+	return nil, fmt.Errorf("laddr must refer to an IP address")
 }
 
 // UPlaneConn represents a U-Plane Connection of GTPv1.

gtpv2/message/create-bearer-res.go

@@ -365,8 +365,7 @@ func (c *CreateBearerResponse) UnmarshalBinary(b []byte) error {
 				c.WLANLocationInformation = i
 			}
 		case ie.TWANIdentifierTimestamp:
-			switch i.Instance() {
-			case 1:
+			if i.Instance() == 1 {
 				c.WLANLocationTimestamp = i
 			}
 		case ie.OverloadControlInformation:

utils/utils.go

@@ -99,13 +99,12 @@ func EncodePLMN(mcc, mnc string) ([]byte, error) {
 	}
 
 	// 2-digit
-	b := make([]byte, 3)
 	if len(mnc) == 2 {
-		b = append(c, n...)
-		return b, nil
+		return append(c, n...), nil
 	}
 
 	// 3-digit
+	b := make([]byte, 3)
 	b[0] = c[0]
 	b[1] = (c[1] & 0x0f) | (n[1] << 4 & 0xf0)
 	b[2] = n[0]