happyDomain/services/dkim.go

114 lines
3.7 KiB
Go

// This file is part of the happyDomain (R) project.
// Copyright (c) 2020-2024 happyDomain
// Authors: Pierre-Olivier Mercier, et al.
//
// This program is offered under a commercial and under the AGPL license.
// For commercial licensing, contact us at <contact@happydomain.org>.
//
// For AGPL licensing:
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package svcs
import (
"encoding/base64"
"fmt"
"strconv"
"strings"
)
type DKIM struct {
Version uint `json:"version" happydomain:"label=Version,placeholder=1,required,description=The version of DKIM to use.,default=1,hidden"`
AcceptableHash []string `json:"h" happydomain:"label=Hash Algorithms,choices=*;sha1;sha256"`
KeyType string `json:"k" happydomain:"label=Key Type,choices=rsa"`
Notes string `json:"n" happydomain:"label=Notes,description=Notes intended for a foreign postmaster"`
PublicKey []byte `json:"p" happydomain:"label=Public Key,placeholder=a0b1c2d3e4f5==,required"`
ServiceType []string `json:"s" happydomain:"label=Service Types,choices=*;email"`
Flags []string `json:"t" happydomain:"label=Flags,choices=y;s"`
}
func (t *DKIM) Analyze(txt string) error {
fields := analyseFields(txt)
if v, ok := fields["v"]; ok {
if !strings.HasPrefix(v, "DKIM") {
return fmt.Errorf("not a valid DKIM record: should begin with v=DKIMv1, seen v=%q", v)
}
version, err := strconv.ParseUint(v[4:], 10, 32)
if err != nil {
return fmt.Errorf("not a valid DKIM record: bad version number: %w", err)
}
t.Version = uint(version)
} else {
return fmt.Errorf("not a valid DKIM record: version not found")
}
if h, ok := fields["h"]; ok {
t.AcceptableHash = strings.Split(h, ":")
} else {
t.AcceptableHash = []string{"*"}
}
if k, ok := fields["k"]; ok {
t.KeyType = k
}
if n, ok := fields["n"]; ok {
t.Notes = n
}
if p, ok := fields["p"]; ok {
var err error
t.PublicKey, err = base64.StdEncoding.DecodeString(p)
if err != nil {
return fmt.Errorf("not a valid DKIM record: public key is not base64 valid: %w", err)
}
}
if s, ok := fields["s"]; ok {
t.ServiceType = strings.Split(s, ":")
} else {
t.ServiceType = []string{"*"}
}
if f, ok := fields["t"]; ok {
t.Flags = strings.Split(f, ":")
}
return nil
}
func (t *DKIM) String() string {
fields := []string{
fmt.Sprintf("v=DKIM%d", t.Version),
}
if len(t.AcceptableHash) > 1 || (len(t.AcceptableHash) > 0 && t.AcceptableHash[0] != "*") {
fields = append(fields, fmt.Sprintf("h=%s", strings.Join(t.AcceptableHash, ":")))
}
if t.KeyType != "" {
fields = append(fields, fmt.Sprintf("k=%s", t.KeyType))
}
if t.Notes != "" {
fields = append(fields, fmt.Sprintf("n=%s", t.Notes))
}
if len(t.PublicKey) > 0 {
fields = append(fields, fmt.Sprintf("p=%s", base64.StdEncoding.EncodeToString(t.PublicKey)))
}
if len(t.ServiceType) > 1 || (len(t.ServiceType) > 0 && t.ServiceType[0] != "*") {
fields = append(fields, fmt.Sprintf("s=%s", strings.Join(t.ServiceType, ":")))
}
if len(t.Flags) > 0 {
fields = append(fields, fmt.Sprintf("t=%s", strings.Join(t.Flags, ":")))
}
return strings.Join(fields, ";")
}