Error rewrites (#43)

* pcap: reuse Frame memory

* slog: reduce heap allocations of addresses; also prevent heap alloc of dhcp options in pcap

* dns: heapless improvement; add StackAsync buffer for more heapless operation; start thinking of errors

* errors: begin standardise errors in lneto

* errors: finish standardization of errors

* fix merge issues

* add more lneto errors to rest of package

* format errors.go

dhcpv4/client.go

@@ -2,8 +2,6 @@ package dhcpv4
 
 import (
 	"encoding/binary"
-	"errors"
-	"fmt"
 	"io"
 	"log/slog"
 	"math"
@@ -80,13 +78,13 @@ func (c *Client) Reset() {
 
 func (c *Client) BeginRequest(xid uint32, cfg RequestConfig) error {
 	if len(cfg.Hostname) > 36 {
-		return errors.New("requested hostname too long")
+		return lneto.ErrInvalidConfig
 	} else if c.state != StateInit && c.state != 0 {
-		return errors.New("dhcp client must be closed/Init before new request")
+		return lneto.ErrInvalidConfig
 	} else if xid == 0 {
-		return errors.New("zero xid")
+		return lneto.ErrInvalidConfig
 	} else if len(cfg.ClientID) > 32 {
-		return errors.New("client ID too long")
+		return lneto.ErrInvalidConfig
 	}
 	c.reset(xid)
 	c.state = StateInit
@@ -143,7 +141,7 @@ func (c *Client) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int)
 	}
 	opts := frm.OptionsPayload()
 	if len(opts) < 255 {
-		return 0, errors.New("too short packet for options")
+		return 0, lneto.ErrShortBuffer
 	}
 
 	var nextState ClientState
@@ -181,7 +179,8 @@ func (c *Client) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int)
 		nextState = StateRequesting
 
 	default:
-		return 0, errors.New("unhandled state" + c.state.String())
+		internal.LogAttrs(nil, slog.LevelError, "dhcpv4:unhandled-state", slog.String("state", c.state.String()))
+		return 0, lneto.ErrBug
 	}
 	n, _ := EncodeOption(opts[numOpts:], OptClientIdentifier, c.clientID...)
 	numOpts += n
@@ -210,13 +209,13 @@ func (c *Client) Demux(carrierData []byte, frameOffset int) error {
 	if err != nil {
 		return err
 	} else if frm.XID() != c.currentXID {
-		return errors.New("dhcpv4 unexpected transaction ID")
+		return lneto.ErrMismatch
 	} else if frm.MagicCookie() != MagicCookie {
-		return errors.New("dhcpv4 bad magic cookie")
+		return lneto.ErrInvalidField
 	}
 	msgType := c.getMessageType(frm)
 	if msgType == MsgNack {
-		return errors.New("dhcp nack received")
+		return lneto.ErrPacketDrop
 	}
 
 	msgOK := msgType == MsgOffer || msgType == MsgAck
@@ -243,7 +242,8 @@ func (c *Client) Demux(carrierData []byte, frameOffset int) error {
 			c.state = StateBound
 		}
 	default:
-		return fmt.Errorf("dhcpv4 unexpected state in recv %s", c.state.String())
+		internal.LogAttrs(nil, slog.LevelError, "dhcpv4:unexpected-recv-state", slog.String("state", c.state.String()))
+		return lneto.ErrBug
 	}
 	if frameOffset > 28 && c.svIPtos == 0 {
 		ifrm, _ := ipv4.NewFrame(carrierData)

dhcpv4/definitions.go

@@ -1,8 +1,9 @@
 package dhcpv4
 
 import (
-	"errors"
 	"unsafe"
+
+	"github.com/soypat/lneto"
 )
 
 //go:generate stringer -type=OptNum,Op,MessageType,ClientState -linecomment -output stringers.go
@@ -52,9 +53,9 @@ func EncodeOption32(dst []byte, opt OptNum, v uint32) (int, error) {
 
 func EncodeOption(dst []byte, opt OptNum, data ...byte) (int, error) {
 	if len(data) > 255 {
-		return 0, errors.New("DHCPv4 option data too long (>255)")
+		return 0, lneto.ErrInvalidLengthField
 	} else if len(dst) < 2+len(data) {
-		return 0, errors.New("DHCP option buffer too short")
+		return 0, lneto.ErrShortBuffer
 	}
 	_ = dst[2+len(data)]
 	dst[0] = byte(opt)

dhcpv4/frame.go

@@ -2,7 +2,6 @@ package dhcpv4
 
 import (
 	"encoding/binary"
-	"errors"
 
 	"github.com/soypat/lneto"
 )
@@ -27,7 +26,7 @@ const (
 // An error is returned if the buffer size is smaller than 240.
 func NewFrame(buf []byte) (Frame, error) {
 	if len(buf) < OptionsOffset {
-		return Frame{}, errSmallFrame
+		return Frame{}, lneto.ErrShortBuffer
 	}
 	return Frame{buf: buf}, nil
 }
@@ -126,9 +125,9 @@ func (frm Frame) ForEachOption(fn func(off int, opt OptNum, data []byte) error)
 	// Parse DHCP options.
 	ptr := OptionsOffset
 	if ptr > len(frm.buf) {
-		return errSmallFrame
+		return lneto.ErrShortBuffer
 	} else if len(frm.buf[ptr:]) == 0 {
-		return errNoOptions
+		return lneto.ErrInvalidField
 	}
 	callback := fn != nil
 	for ptr+1 < len(frm.buf) {
@@ -141,7 +140,7 @@ func (frm Frame) ForEachOption(fn func(off int, opt OptNum, data []byte) error)
 		}
 		optlen := int(frm.buf[ptr+1])
 		if ptr+2+optlen > len(frm.buf) {
-			return errDHCPBadOption
+			return lneto.ErrInvalidLengthField
 		}
 		if callback {
 			optionData := frm.buf[ptr+2 : ptr+2+optlen]
@@ -158,16 +157,9 @@ func (frm Frame) ForEachOption(fn func(off int, opt OptNum, data []byte) error)
 // Validation API.
 //
 
-var (
-	errSmallFrame    = errors.New("DHCPv4: frame size <240")
-	errDHCPBadOption = errors.New("DHCPv4: opt length exceeds payload")
-	errNoOptions     = errors.New("DHCPv4: no options")
-	errOptionNotFit  = errors.New("DHCPv4: options dont fit")
-)
-
 func (frm Frame) ValidateSize(vld *lneto.Validator) {
 	err := frm.ForEachOption(nil) // Does all necessary validation.
 	if err != nil {
-		vld.AddError(errDHCPBadOption)
+		vld.AddError(lneto.ErrInvalidLengthField)
 	}
 }

dhcpv4/server.go

@@ -10,6 +10,8 @@ import (
 	"github.com/soypat/lneto/internal"
 )
 
+var errOptionNotFit = errors.New("DHCPv4: options dont fit")
+
 type Server struct {
 	connID       uint64
 	nextAddr     netip.Addr