Simplify and unify various returns (#893)

client.go

@@ -325,11 +325,7 @@ func (co *Conn) Read(p []byte) (n int, err error) {
 		return tcpRead(r, p[:l])
 	}
 	// UDP connection
-	n, err = co.Conn.Read(p)
-	if err != nil {
-		return n, err
-	}
-	return n, err
+	return co.Conn.Read(p)
 }
 
 // WriteMsg sends a message through the connection co.
@@ -351,10 +347,8 @@ func (co *Conn) WriteMsg(m *Msg) (err error) {
 	if err != nil {
 		return err
 	}
-	if _, err = co.Write(out); err != nil {
-		return err
-	}
-	return nil
+	_, err = co.Write(out)
+	return err
 }
 
 // Write implements the net.Conn Write method.
@@ -376,8 +370,7 @@ func (co *Conn) Write(p []byte) (n int, err error) {
 		n, err := io.Copy(w, bytes.NewReader(p))
 		return int(n), err
 	}
-	n, err = co.Conn.Write(p)
-	return n, err
+	return co.Conn.Write(p)
 }
 
 // Return the appropriate timeout for a specific request
@@ -444,11 +437,7 @@ func ExchangeConn(c net.Conn, m *Msg) (r *Msg, err error) {
 // DialTimeout acts like Dial but takes a timeout.
 func DialTimeout(network, address string, timeout time.Duration) (conn *Conn, err error) {
 	client := Client{Net: network, Dialer: &net.Dialer{Timeout: timeout}}
-	conn, err = client.Dial(address)
-	if err != nil {
-		return nil, err
-	}
-	return conn, nil
+	return client.Dial(address)
 }
 
 // DialWithTLS connects to the address on the named network with TLS.
@@ -457,12 +446,7 @@ func DialWithTLS(network, address string, tlsConfig *tls.Config) (conn *Conn, er
 		network += "-tls"
 	}
 	client := Client{Net: network, TLSConfig: tlsConfig}
-	conn, err = client.Dial(address)
-
-	if err != nil {
-		return nil, err
-	}
-	return conn, nil
+	return client.Dial(address)
 }
 
 // DialTimeoutWithTLS acts like DialWithTLS but takes a timeout.
@@ -471,11 +455,7 @@ func DialTimeoutWithTLS(network, address string, tlsConfig *tls.Config, timeout
 		network += "-tls"
 	}
 	client := Client{Net: network, Dialer: &net.Dialer{Timeout: timeout}, TLSConfig: tlsConfig}
-	conn, err = client.Dial(address)
-	if err != nil {
-		return nil, err
-	}
-	return conn, nil
+	return client.Dial(address)
 }
 
 // ExchangeContext acts like Exchange, but honors the deadline on the provided

labels.go

@@ -36,8 +36,7 @@ func SplitDomainName(s string) (labels []string) {
 		}
 	}
 
-	labels = append(labels, s[begin:fqdnEnd])
-	return labels
+	return append(labels, s[begin:fqdnEnd])
 }
 
 // CompareDomainName compares the names s1 and s2 and

msg.go

@@ -1072,7 +1072,7 @@ func compressionLenSearch(c map[string]struct{}, s string, msgOff int) (int, boo
 }
 
 // Copy returns a new RR which is a deep-copy of r.
-func Copy(r RR) RR { r1 := r.copy(); return r1 }
+func Copy(r RR) RR { return r.copy() }
 
 // Len returns the length (in octets) of the uncompressed RR in wire format.
 func Len(r RR) int { return r.len(0, nil) }
@@ -1187,7 +1187,10 @@ func (dh *Header) pack(msg []byte, off int, compression compressionMap, compress
 		return off, err
 	}
 	off, err = packUint16(dh.Arcount, msg, off)
-	return off, err
+	if err != nil {
+		return off, err
+	}
+	return off, nil
 }
 
 func unpackMsgHdr(msg []byte, off int) (Header, int, error) {
@@ -1216,7 +1219,10 @@ func unpackMsgHdr(msg []byte, off int) (Header, int, error) {
 		return dh, off, err
 	}
 	dh.Arcount, off, err = unpackUint16(msg, off)
-	return dh, off, err
+	if err != nil {
+		return dh, off, err
+	}
+	return dh, off, nil
 }
 
 // setHdr set the header in the dns using the binary data in dh.

privaterr.go

@@ -39,11 +39,12 @@ func mkPrivateRR(rrtype uint16) *PrivateRR {
 	}
 
 	anyrr := rrfunc()
-	switch rr := anyrr.(type) {
-	case *PrivateRR:
-		return rr
+	rr, ok := anyrr.(*PrivateRR)
+	if !ok {
+		panic(fmt.Sprintf("dns: RR is not a PrivateRR, TypeToRR[%d] generator returned %T", rrtype, anyrr))
 	}
-	panic(fmt.Sprintf("dns: RR is not a PrivateRR, TypeToRR[%d] generator returned %T", rrtype, anyrr))
+
+	return rr
 }
 
 // Header return the RR header of r.
@@ -82,11 +83,7 @@ func (r *PrivateRR) pack(msg []byte, off int, compression compressionMap, compre
 func (r *PrivateRR) unpack(msg []byte, off int) (int, error) {
 	off1, err := r.Data.Unpack(msg[off:])
 	off += off1
-	if err != nil {
-		return off, err
-	}
-
-	return off, nil
+	return off, err
 }
 
 // PrivateHandle registers a private resource record type. It requires

server.go

@@ -463,11 +463,10 @@ var testShutdownNotify *sync.Cond
 
 // getReadTimeout is a helper func to use system timeout if server did not intend to change it.
 func (srv *Server) getReadTimeout() time.Duration {
-	rtimeout := dnsTimeout
 	if srv.ReadTimeout != 0 {
-		rtimeout = srv.ReadTimeout
+		return srv.ReadTimeout
 	}
-	return rtimeout
+	return dnsTimeout
 }
 
 // serveTCP starts a TCP listener for the server.
@@ -783,8 +782,7 @@ func (w *response) Write(m []byte) (int, error) {
 
 	switch {
 	case w.udp != nil:
-		n, err := WriteToSessionUDP(w.udp, m, w.udpSession)
-		return n, err
+		return WriteToSessionUDP(w.udp, m, w.udpSession)
 	case w.tcp != nil:
 		lm := len(m)
 		if lm < 2 {

smimea.go

@@ -14,10 +14,7 @@ func (r *SMIMEA) Sign(usage, selector, matchingType int, cert *x509.Certificate)
 	r.MatchingType = uint8(matchingType)
 
 	r.Certificate, err = CertificateToDANE(r.Selector, r.MatchingType, cert)
-	if err != nil {
-		return err
-	}
-	return nil
+	return err
 }
 
 // Verify verifies a SMIMEA record against an SSL certificate. If it is OK

tlsa.go

@@ -14,10 +14,7 @@ func (r *TLSA) Sign(usage, selector, matchingType int, cert *x509.Certificate) (
 	r.MatchingType = uint8(matchingType)
 
 	r.Certificate, err = CertificateToDANE(r.Selector, r.MatchingType, cert)
-	if err != nil {
-		return err
-	}
-	return nil
+	return err
 }
 
 // Verify verifies a TLSA record against an SSL certificate. If it is OK

tsig.go

@@ -134,12 +134,11 @@ func TsigGenerate(m *Msg, secret, requestMAC string, timersOnly bool) ([]byte, s
 	t.OrigId = m.Id
 
 	tbuf := make([]byte, Len(t))
-	if off, err := PackRR(t, tbuf, 0, nil, false); err == nil {
-		tbuf = tbuf[:off] // reset to actual size used
-	} else {
+	off, err := PackRR(t, tbuf, 0, nil, false)
+	if err != nil {
 		return nil, "", err
 	}
-	mbuf = append(mbuf, tbuf...)
+	mbuf = append(mbuf, tbuf[:off]...)
 	// Update the ArCount directly in the buffer.
 	binary.BigEndian.PutUint16(mbuf[10:], uint16(len(m.Extra)+1))
 

udp_windows.go

@@ -20,15 +20,13 @@ func ReadFromSessionUDP(conn *net.UDPConn, b []byte) (int, *SessionUDP, error) {
 	if err != nil {
 		return n, nil, err
 	}
-	session := &SessionUDP{raddr.(*net.UDPAddr)}
-	return n, session, err
+	return n, &SessionUDP{raddr.(*net.UDPAddr)}, err
 }
 
 // WriteToSessionUDP acts just like net.UDPConn.WriteTo(), but uses a *SessionUDP instead of a net.Addr.
 // TODO(fastest963): Once go1.10 is released, use WriteMsgUDP.
 func WriteToSessionUDP(conn *net.UDPConn, b []byte, session *SessionUDP) (int, error) {
-	n, err := conn.WriteTo(b, session.raddr)
-	return n, err
+	return conn.WriteTo(b, session.raddr)
 }
 
 // TODO(fastest963): Once go1.10 is released and we can use *MsgUDP methods

xfr.go

@@ -243,24 +243,18 @@ func (t *Transfer) WriteMsg(m *Msg) (err error) {
 	if err != nil {
 		return err
 	}
-	if _, err = t.Write(out); err != nil {
-		return err
-	}
-	return nil
+	_, err = t.Write(out)
+	return err
 }
 
 func isSOAFirst(in *Msg) bool {
-	if len(in.Answer) > 0 {
-		return in.Answer[0].Header().Rrtype == TypeSOA
-	}
-	return false
+	return len(in.Answer) > 0 &&
+		in.Answer[0].Header().Rrtype == TypeSOA
 }
 
 func isSOALast(in *Msg) bool {
-	if len(in.Answer) > 0 {
-		return in.Answer[len(in.Answer)-1].Header().Rrtype == TypeSOA
-	}
-	return false
+	return len(in.Answer) > 0 &&
+		in.Answer[len(in.Answer)-1].Header().Rrtype == TypeSOA
 }
 
 const errXFR = "bad xfr rcode: %d"