routedns/edns0ede.go

package rdns

import (
	"github.com/miekg/dns"
)

type EDNS0EDETemplate struct {
	infoCode     uint16
	textTemplate *Template
}

type EDNS0EDEInput struct {
	*dns.Msg
	*BlocklistMatch
}

func NewEDNS0EDETemplate(infoCode uint16, extraText string) (*EDNS0EDETemplate, error) {
	if infoCode == 0 && extraText == "" {
		return nil, nil
	}

	tpl, err := NewTemplate(extraText)
	if err != nil {
		return nil, err
	}

	return &EDNS0EDETemplate{
		infoCode:     infoCode,
		textTemplate: tpl,
	}, nil
}

// Apply executes the template for the EDNS0-EDE record text, e.g. replacing
// placeholders in the Text with Query names, then adding the EDE record to
// the given msg.
func (t *EDNS0EDETemplate) Apply(msg *dns.Msg, in EDNS0EDEInput) error {
	if t == nil {
		return nil
	}
	var question dns.Question
	if len(in.Question) > 0 {
		question = in.Question[0]
	}
	input := templateInput{
		ID:            in.Id,
		Question:      question.Name,
		QuestionClass: dns.ClassToString[question.Qclass],
		QuestionType:  dns.TypeToString[question.Qtype],
	}
	if in.BlocklistMatch != nil {
		input.BlocklistRule = in.Rule
		input.Blocklist = in.List
	}
	extraText, err := t.textTemplate.Apply(input)
	if err != nil {
		return err
	}
	ede := &dns.EDNS0_EDE{
		InfoCode:  t.infoCode,
		ExtraText: extraText,
	}
	msg.SetEdns0(4096, false)
	opt := msg.IsEdns0()
	opt.Option = append(opt.Option, ede)
	return nil
}