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package rfc1035label
import (
"fmt"
"strings"
)
// This implements the compression from RFC 1035, section 4.1.4
// https://tools.ietf.org/html/rfc1035
// LabelsFromBytes decodes a serialized stream and returns a list of labels
func LabelsFromBytes(buf []byte) ([]string, error) {
var (
pos = 0
domains = make([]string, 0)
label = ""
)
for {
if pos >= len(buf) {
return domains, nil
}
length := int(buf[pos])
pos++
if length == 0 {
domains = append(domains, label)
label = ""
}
if len(buf)-pos < length {
return nil, fmt.Errorf("DomainNamesFromBytes: invalid short label length")
}
if label != "" {
label += "."
}
label += string(buf[pos : pos+length])
pos += length
}
}
// LabelToBytes encodes a label and returns a serialized stream of bytes
func LabelToBytes(label string) []byte {
var encodedLabel []byte
if len(label) == 0 {
return []byte{0}
}
for _, part := range strings.Split(label, ".") {
encodedLabel = append(encodedLabel, byte(len(part)))
encodedLabel = append(encodedLabel, []byte(part)...)
}
return append(encodedLabel, 0)
}
// LabelsToBytes encodes a list of labels and returns a serialized stream of
// bytes
func LabelsToBytes(labels []string) []byte {
var encodedLabels []byte
for _, label := range labels {
encodedLabels = append(encodedLabels, LabelToBytes(label)...)
}
return encodedLabels
}
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