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89 lines
2.3 KiB
89 lines
2.3 KiB
package realm
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import (
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"fmt"
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"os"
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"github.com/miekg/dns"
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)
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// A Zone a container for records parsed from a zone file.
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type Zone struct {
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records []dns.RR
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}
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// ParseZone will attempt to parse a zone file from the provided filename and return a Zone.
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// ParseZone will return an error if the file provided does not exist or could not be properly parsed.
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func ParseZone(filename string) (*Zone, error) {
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var zone *Zone
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var err error
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zone = &Zone{
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records: make([]dns.RR, 0),
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}
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// Open the file
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var file *os.File
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file, err = os.Open(filename)
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if err != nil {
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return nil, fmt.Errorf("could not parse zone file \"%s\": \"%s\"", filename, err)
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}
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defer file.Close()
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// Parse the file into records
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var tokens chan *dns.Token
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tokens = dns.ParseZone(file, "", "")
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for token := range tokens {
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if token.Error != nil {
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return nil, fmt.Errorf("could not parse zone file \"%s\": \"%s\"", filename, token.Error)
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}
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zone.records = append(zone.records, token.RR)
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}
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return zone, nil
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}
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// Lookup will find all records which we should respond with for the given name, request type, and request class.
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func (zone *Zone) Lookup(name string, reqType uint16, reqClass uint16) []dns.RR {
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name = dns.Fqdn(name)
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var records []dns.RR
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records = make([]dns.RR, 0)
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for _, record := range zone.records {
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var header *dns.RR_Header
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header = record.Header()
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// Skip this record if the class does not match up
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if header.Class != reqClass && reqClass != dns.ClassANY {
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continue
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}
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// If this record is an SOA then check name against Mbox
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if header.Rrtype == dns.TypeSOA {
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var soa *dns.SOA
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soa = record.(*dns.SOA)
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if soa.Mbox == name {
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records = append(records, soa)
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}
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}
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// Skip this record if the name does not match
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if header.Name != name {
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continue
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}
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// Collect this record if the types match or this record is a CNAME
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if reqType == dns.TypeANY || reqType == header.Rrtype {
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records = append(records, record)
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} else if header.Rrtype == dns.TypeCNAME {
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// Append this CNAME record as a response
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records = append(records, record)
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// Attempt to resolve this CNAME record
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var cname *dns.CNAME
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cname = record.(*dns.CNAME)
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var cnameRecords []dns.RR
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cnameRecords = zone.Lookup(dns.Fqdn(cname.Target), reqType, reqClass)
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records = append(records, cnameRecords...)
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}
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}
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return records
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}
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