implement more ZIP packets (ATP)

atalk/zip/getzonelist.go

@@ -0,0 +1,125 @@
+/*
+   Copyright 2024 Josh Deprez
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package zip
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+
+	"gitea.drjosh.dev/josh/jrouter/atalk/atp"
+)
+
+type GetZonesPacket struct {
+	// "These requests always ask for a single response packet."
+	// TReq   = 0b01000000
+	// Bitmap = 0b00000001
+	TID uint16
+	// --- ATP user bytes
+	Function Function // 7, 8, or 9
+	// Pad uint8 = 0
+	StartIndex uint16 // always 0 for
+}
+
+func (p *GetZonesPacket) MarshalTReq() (*atp.TReq, error) {
+	return &atp.TReq{
+		Bitmap:        0b00000001,
+		TransactionID: p.TID,
+		UserBytes: [4]byte{
+			byte(p.Function), 0, byte(p.StartIndex >> 8), byte(p.StartIndex & 0xFF),
+		},
+	}, nil
+}
+
+type GetZonesReplyPacket struct {
+	// TResp    = 0b10000000
+	// Sequence = 0
+	TID uint16
+	// --- ATP user bytes
+	LastFlag bool // not used for GetMyZone
+	// Pad uint8 = 0
+	// ZoneCount uint16
+	// --- ATP data bytes
+	Zones []string // length-prefixed
+}
+
+func (p *GetZonesReplyPacket) MarshalTResp() (*atp.TResp, error) {
+	r := &atp.TResp{
+		EndOfMessage:  true,
+		Sequence:      0,
+		TransactionID: p.TID,
+	}
+	if p.LastFlag {
+		r.UserBytes[0] = 1
+	}
+	zc := uint16(len(p.Zones))
+	r.UserBytes[2] = byte(zc >> 8)
+	r.UserBytes[3] = byte(zc & 0xFF)
+	b := bytes.NewBuffer(nil)
+	for _, z := range p.Zones {
+		if len(z) > 32 {
+			return nil, fmt.Errorf("zone name %q too long [%d > 32]", z, len(z))
+		}
+		b.WriteByte(byte(len(z)))
+		b.WriteString(z)
+	}
+	r.Data = b.Bytes()
+	return r, nil
+}
+
+func UnmarshalTReq(treq *atp.TReq) (*GetZonesPacket, error) {
+	if treq == nil {
+		return nil, fmt.Errorf("nil *TReq")
+	}
+	fn := treq.UserBytes[0]
+	if fn != FunctionGetZoneList && fn != FunctionGetLocalZones && fn != FunctionGetMyZone {
+		return nil, fmt.Errorf("invalid ZIP function %d", fn)
+	}
+	return &GetZonesPacket{
+		TID:        treq.TransactionID,
+		Function:   Function(treq.UserBytes[0]),
+		StartIndex: binary.BigEndian.Uint16(treq.UserBytes[2:4]),
+	}, nil
+}
+
+func UnmarshalTResp(tresp *atp.TResp) (*GetZonesReplyPacket, error) {
+	if tresp == nil {
+		return nil, fmt.Errorf("nil *TResp")
+	}
+	p := &GetZonesReplyPacket{
+		TID:      tresp.TransactionID,
+		LastFlag: tresp.UserBytes[0] != 0,
+	}
+	data := tresp.Data
+	zc := binary.BigEndian.Uint16(tresp.UserBytes[2:4])
+	for range zc {
+		if len(data) < 1 {
+			return nil, fmt.Errorf("insufficient remaining TResp data length %d for length-prefixed string", len(data))
+		}
+		slen := data[0]
+		data = data[1:]
+		if len(data) < int(slen) {
+			return nil, fmt.Errorf("insufficient remaining TResp data length %d for length-%d prefixed string", len(data), slen)
+		}
+		p.Zones = append(p.Zones, string(data[:slen]))
+		data = data[slen:]
+	}
+	if len(data) > 0 {
+		return nil, fmt.Errorf("%d bytes left over at end of packet", len(data))
+	}
+	return p, nil
+}

atalk/zip/zip.go

@@ -24,12 +24,18 @@ import (
 type Function uint8
 
 const (
+	// ZIP packets
 	FunctionQuery           = 1
 	FunctionReply           = 2
 	FunctionGetNetInfo      = 5
 	FunctionGetNetInfoReply = 6
 	FunctionNotify          = 7
 	FunctionExtendedReply   = 8
+
+	// ATP packets
+	FunctionGetMyZone     = 7
+	FunctionGetZoneList   = 8
+	FunctionGetLocalZones = 9
 )
 
 // Non-ATP packets only