123 lines
3.1 KiB
Go
123 lines
3.1 KiB
Go
package packer
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import (
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"bytes"
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"fmt"
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"net"
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"strconv"
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"strings"
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)
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const (
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_ = iota // skip the iota value of 0
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packerV1 byte = 255 - iota
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packerV2
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)
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//Packer -- contains both header and data
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type Packer struct {
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Header *packerHeader
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Data *packerData
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}
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//NewPacker -- Structre
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func NewPacker() (p *Packer) {
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p = new(Packer)
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p.Header = newPackerHeader()
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p.Data = newPackerData()
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return
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}
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func splitHeader(header []byte, names []string) (map[string]string, error) {
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parts := strings.Split(string(header), ",")
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if p, n := len(parts), len(names); p > n {
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return nil, fmt.Errorf("Header contains %d extra fields", p-n)
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} else if p < n {
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return nil, fmt.Errorf("Header missing fields %q", names[p:])
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}
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result := make(map[string]string, len(names))
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for ind, key := range names {
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result[key] = parts[ind]
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}
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return result, nil
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}
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//ReadMessage -
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func ReadMessage(b []byte) (*Packer, error) {
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fmt.Println("ReadMessage")
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// Detect protocol in use
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if b[0] == packerV1 {
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// Separate the header and body using the header length in the second byte.
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p := NewPacker()
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header := b[2 : b[1]+2]
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data := b[b[1]+2:]
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// Handle the different parts of the header.
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parts, err := splitHeader(header, []string{"address family", "address", "port", "data length", "service"})
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if err != nil {
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return nil, err
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}
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if familyText := parts["address family"]; familyText == addressFamilyText[FamilyIPv4] {
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p.Header.family = FamilyIPv4
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} else if familyText == addressFamilyText[FamilyIPv6] {
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p.Header.family = FamilyIPv6
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} else {
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return nil, fmt.Errorf("Address family %q not supported", familyText)
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}
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p.Header.address = net.ParseIP(parts["address"])
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if p.Header.address == nil {
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return nil, fmt.Errorf("Invalid network address %q", parts["address"])
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} else if p.Header.Family() == FamilyIPv4 && p.Header.address.To4() == nil {
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return nil, fmt.Errorf("Address %q is not in address family %s", parts["address"], p.Header.FamilyText())
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}
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//handle port
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if port, err := strconv.Atoi(parts["port"]); err != nil {
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return nil, fmt.Errorf("Error converting port %q: %v", parts["port"], err)
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} else if port <= 0 || port > 65535 {
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return nil, fmt.Errorf("Port %d out of range", port)
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} else {
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p.Header.Port = port
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}
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//handle data length
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if dataLen, err := strconv.Atoi(parts["data length"]); err != nil {
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return nil, fmt.Errorf("Error converting data length %q: %v", parts["data length"], err)
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} else if dataLen != len(data) {
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return nil, fmt.Errorf("Data length %d doesn't match received length %d", dataLen, len(data))
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}
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//handle Service
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p.Header.Service = parts["service"]
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//handle payload
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p.Data.AppendBytes(data)
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return p, nil
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}
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return nil, fmt.Errorf("Version %d not supported", 255-b[0])
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}
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//PackV1 -- Outputs version 1 of packer
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func (p *Packer) PackV1() bytes.Buffer {
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header := strings.Join([]string{
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p.Header.FamilyText(),
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p.Header.AddressString(),
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strconv.Itoa(p.Header.Port),
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strconv.Itoa(p.Data.DataLen()),
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p.Header.Service,
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}, ",")
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var buf bytes.Buffer
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buf.WriteByte(packerV1)
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buf.WriteByte(byte(len(header)))
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buf.WriteString(header)
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buf.Write(p.Data.Data())
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return buf
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}
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