126 lines
3.5 KiB
Go
126 lines
3.5 KiB
Go
package mqtpp
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import (
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"fmt"
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"strconv"
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"strings"
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"unicode/utf8"
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"google.golang.org/protobuf/encoding/protowire"
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)
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const NodeNumBroadcast uint32 = 0xffffffff
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type TextMessageBuildOptions struct {
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FromNodeNum uint32
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ToNodeNum uint32
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PacketID uint32
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ChannelID string
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GatewayID string
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Text string
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PSK []byte
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Encrypt bool
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ViaMQTT bool
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}
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func BuildTextMessageServiceEnvelope(opts TextMessageBuildOptions) ([]byte, error) {
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if opts.FromNodeNum == 0 {
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return nil, fmt.Errorf("from node number is required")
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}
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if opts.PacketID == 0 {
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return nil, fmt.Errorf("packet id is required")
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}
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if opts.ChannelID == "" {
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return nil, fmt.Errorf("channel id is required")
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}
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if strings.TrimSpace(opts.GatewayID) == "" {
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opts.GatewayID = NodeNumToID(opts.FromNodeNum)
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}
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if opts.Text == "" {
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return nil, fmt.Errorf("text is required")
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}
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if !utf8.ValidString(opts.Text) {
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return nil, fmt.Errorf("text must be valid utf-8")
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}
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data := buildDataPacket(textMessageApp, []byte(opts.Text))
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packet, err := buildMeshPacket(opts, data)
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if err != nil {
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return nil, err
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}
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return buildServiceEnvelope(packet, opts.ChannelID, opts.GatewayID), nil
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}
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func NodeNumToID(nodeNum uint32) string {
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return nodeNumToID(nodeNum)
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}
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func ParseNodeID(nodeID string) (uint32, error) {
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value := strings.TrimSpace(nodeID)
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if value == "" {
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return 0, fmt.Errorf("node id is required")
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}
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value = strings.TrimPrefix(value, "!")
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if len(value) != 8 {
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return 0, fmt.Errorf("node id must be !xxxxxxxx")
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}
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num, err := strconv.ParseUint(value, 16, 32)
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if err != nil {
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return 0, fmt.Errorf("invalid node id: %w", err)
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}
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return uint32(num), nil
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}
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func buildDataPacket(portnum uint32, payload []byte) []byte {
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var out []byte
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out = protowire.AppendTag(out, 1, protowire.VarintType)
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out = protowire.AppendVarint(out, uint64(portnum))
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out = protowire.AppendTag(out, 2, protowire.BytesType)
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out = protowire.AppendBytes(out, payload)
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return out
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}
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func buildMeshPacket(opts TextMessageBuildOptions, data []byte) ([]byte, error) {
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var out []byte
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out = protowire.AppendTag(out, 1, protowire.Fixed32Type)
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out = protowire.AppendFixed32(out, opts.FromNodeNum)
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out = protowire.AppendTag(out, 2, protowire.Fixed32Type)
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out = protowire.AppendFixed32(out, opts.ToNodeNum)
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if opts.Encrypt {
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if len(opts.PSK) == 0 {
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return nil, fmt.Errorf("psk is required for encrypted text message")
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}
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ciphertext, err := cryptAESCTR(opts.PSK, opts.FromNodeNum, opts.PacketID, data)
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if err != nil {
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return nil, err
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}
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out = protowire.AppendTag(out, 3, protowire.VarintType)
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out = protowire.AppendVarint(out, uint64(channelHash(opts.ChannelID, opts.PSK)))
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out = protowire.AppendTag(out, 5, protowire.BytesType)
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out = protowire.AppendBytes(out, ciphertext)
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} else {
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out = protowire.AppendTag(out, 4, protowire.BytesType)
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out = protowire.AppendBytes(out, data)
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}
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out = protowire.AppendTag(out, 6, protowire.Fixed32Type)
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out = protowire.AppendFixed32(out, opts.PacketID)
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if opts.ViaMQTT {
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out = protowire.AppendTag(out, 14, protowire.VarintType)
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out = protowire.AppendVarint(out, 1)
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}
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return out, nil
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}
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func buildServiceEnvelope(packet []byte, channelID string, gatewayID string) []byte {
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var out []byte
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out = protowire.AppendTag(out, 1, protowire.BytesType)
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out = protowire.AppendBytes(out, packet)
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out = protowire.AppendTag(out, 2, protowire.BytesType)
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out = protowire.AppendBytes(out, []byte(channelID))
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out = protowire.AppendTag(out, 3, protowire.BytesType)
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out = protowire.AppendBytes(out, []byte(gatewayID))
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return out
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}
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