Add round-robin implementation (#66)

* add handler.encapsulateNode

* implement round robin handler approach

* simplify round robin implementation

* leave TODO

* internet.node touch up

* fix conflict resolve f-up

* replace certain ErrShortBuffer with ErrTruncatedFrame error

dns/definitions.go

@@ -16,7 +16,6 @@ var (
 	errNoNullTerm     = errors.New("DNS name missing null terminator")
 	errCalcLen        = errors.New("DNS calculated name label length exceeds remaining buffer length")
 	errCantAddLabel   = errors.New("long/empty/zterm/escape DNS label or not enough space")
-	errBaseLen        = lneto.ErrShortBuffer
 	errReserved       = errors.New("segment prefix is reserved")
 	errTooManyPtr     = errors.New("too many pointers (>10)")
 	errInvalidPtr     = errors.New("invalid pointer")
@@ -27,10 +26,10 @@ var (
 	errZeroSegLen     = errors.New("zero length segment")
 	errResTooLong     = errors.New("resource length too long")
 
-	errTooManyQuestions   = lneto.ErrBufferFull
-	errTooManyAnswers     = lneto.ErrBufferFull
-	errTooManyAuthorities = lneto.ErrBufferFull
-	errTooManyAdditionals = lneto.ErrBufferFull
+	errTooManyQuestions   = lneto.ErrExhausted
+	errTooManyAnswers     = lneto.ErrExhausted
+	errTooManyAuthorities = lneto.ErrExhausted
+	errTooManyAdditionals = lneto.ErrExhausted
 
 	errNonCanonicalName = errors.New("name is not in canonical format (it must end with a .)")
 	errStringTooLong    = errors.New("character string exceeds maximum length (255)")
@@ -49,7 +48,7 @@ type Frame struct {
 
 func NewFrame(buf []byte) (Frame, error) {
 	if len(buf) < SizeHeader {
-		return Frame{}, errBaseLen
+		return Frame{}, lneto.ErrTruncatedFrame
 	}
 	return Frame{buf: buf}, nil
 }

dns/dns.go

@@ -8,6 +8,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/soypat/lneto"
 	"github.com/soypat/lneto/internal"
 )
 
@@ -196,7 +197,7 @@ func skipQuestion(msg []byte, off uint16) (_ uint16, err error) {
 		return off, err
 	}
 	if off+4 > uint16(len(msg)) {
-		return off, errBaseLen
+		return off, lneto.ErrTruncatedFrame
 	}
 	return off + 4, nil
 }
@@ -210,7 +211,7 @@ func skipResource(msg []byte, off uint16) (_ uint16, err error) {
 	datalen := binary.BigEndian.Uint16(msg[off+8:])
 	off += datalen + 10
 	if off > uint16(len(msg)) {
-		return off, errBaseLen
+		return off, lneto.ErrTruncatedFrame
 	}
 	return off, nil
 }
@@ -610,7 +611,7 @@ func visitAllLabels(msg []byte, off uint16, fn func(b []byte), allowCompression
 LOOP:
 	for {
 		if currOff >= uint16(len(msg)) {
-			return off, errBaseLen
+			return off, lneto.ErrTruncatedFrame
 		}
 		c := uint16(msg[currOff])
 		currOff++