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https://github.com/netbirdio/netbird.git
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111 lines
2.9 KiB
Go
111 lines
2.9 KiB
Go
// Package dns implement dns types and standard methods and functions
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// to parse and normalize dns records and configuration
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package dns
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import (
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"fmt"
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"net"
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"regexp"
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"strings"
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"github.com/miekg/dns"
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"golang.org/x/net/idna"
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)
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const (
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// DefaultDNSPort well-known port number
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DefaultDNSPort = 53
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// RootZone is a string representation of the root zone
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RootZone = "."
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// DefaultClass is the class supported by the system
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DefaultClass = "IN"
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)
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const invalidHostLabel = "[^a-zA-Z0-9-]+"
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// Config represents a dns configuration that is exchanged between management and peers
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type Config struct {
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// ServiceEnable indicates if the service should be enabled
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ServiceEnable bool
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// NameServerGroups contains a list of nameserver group
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NameServerGroups []*NameServerGroup
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// CustomZones contains a list of custom zone
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CustomZones []CustomZone
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}
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// CustomZone represents a custom zone to be resolved by the dns server
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type CustomZone struct {
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// Domain is the zone's domain
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Domain string
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// Records custom zone records
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Records []SimpleRecord
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}
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// SimpleRecord provides a simple DNS record specification for CNAME, A and AAAA records
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type SimpleRecord struct {
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// Name domain name
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Name string
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// Type of record, 1 for A, 5 for CNAME, 28 for AAAA. see https://pkg.go.dev/github.com/miekg/dns@v1.1.41#pkg-constants
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Type int
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// Class dns class, currently use the DefaultClass for all records
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Class string
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// TTL time-to-live for the record
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TTL int
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// RData is the actual value resolved in a dns query
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RData string
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}
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// String returns a string of the simple record formatted as:
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// <Name> <TTL> <Class> <Type> <RDATA>
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func (s SimpleRecord) String() string {
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fqdn := dns.Fqdn(s.Name)
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return fmt.Sprintf("%s %d %s %s %s", fqdn, s.TTL, s.Class, dns.Type(s.Type).String(), s.RData)
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}
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// Len returns the length of the RData field, based on its type
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func (s SimpleRecord) Len() uint16 {
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emptyString := s.RData == ""
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switch s.Type {
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case 1:
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if emptyString {
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return 0
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}
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return net.IPv4len
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case 5:
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if emptyString || s.RData == "." {
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return 1
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}
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return uint16(len(s.RData) + 1)
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case 28:
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if emptyString {
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return 0
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}
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return net.IPv6len
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default:
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return 0
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}
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}
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// GetParsedDomainLabel returns a domain label with max 59 characters,
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// parsed for old Hosts.txt requirements, and converted to ASCII and lowercase
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func GetParsedDomainLabel(name string) (string, error) {
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labels := dns.SplitDomainName(name)
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if len(labels) == 0 {
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return "", fmt.Errorf("got empty label list for name \"%s\"", name)
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}
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rawLabel := labels[0]
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ascii, err := idna.Punycode.ToASCII(rawLabel)
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if err != nil {
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return "", fmt.Errorf("unable to convert host label to ASCII, error: %v", err)
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}
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invalidHostMatcher := regexp.MustCompile(invalidHostLabel)
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validHost := strings.ToLower(invalidHostMatcher.ReplaceAllString(ascii, "-"))
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if len(validHost) > 58 {
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validHost = validHost[:59]
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}
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return validHost, nil
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}
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