| 224 | } |
| 225 | |
| 226 | func ExtractFromDomain(hdr textproto.Header) (string, error) { |
| 227 | // TODO(GH emersion/go-message#75): Add textproto.Header.Count method. |
| 228 | var firstFrom string |
| 229 | for fields := hdr.FieldsByKey("From"); fields.Next(); { |
| 230 | if firstFrom == "" { |
| 231 | firstFrom = fields.Value() |
| 232 | } else { |
| 233 | return "", errors.New("dmarc: multiple From header fields are not allowed") |
| 234 | } |
| 235 | } |
| 236 | if firstFrom == "" { |
| 237 | return "", errors.New("dmarc: missing From header field") |
| 238 | } |
| 239 | |
| 240 | hdrFromList, err := mail.ParseAddressList(firstFrom) |
| 241 | if err != nil { |
| 242 | return "", fmt.Errorf("dmarc: malformed From header field: %s", strings.TrimPrefix(err.Error(), "mail: ")) |
| 243 | } |
| 244 | if len(hdrFromList) > 1 { |
| 245 | return "", errors.New("dmarc: multiple addresses in From field are not allowed") |
| 246 | } |
| 247 | if len(hdrFromList) == 0 { |
| 248 | return "", errors.New("dmarc: missing address in From field") |
| 249 | } |
| 250 | _, domain, err := address.Split(hdrFromList[0].Address) |
| 251 | if err != nil { |
| 252 | return "", fmt.Errorf("dmarc: malformed From header field: %w", err) |
| 253 | } |
| 254 | |
| 255 | return domain, nil |
| 256 | } |