go-mail/eml.go
Winni Neessen e7c717d0fc
"Rename Mime10 to MIME10 in codebase
Renamed field 'Mime10' to 'MIME10' across multiple files for canonical representation and consistency with standard MIME naming format in the protocol."
2023-10-13 15:23:28 +02:00

148 lines
3.6 KiB
Go

// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors
//
// SPDX-License-Identifier: MIT
package mail
import (
"bytes"
"errors"
"fmt"
"mime"
nm "net/mail"
"os"
"strings"
)
// EMLToMsg will open an parse a .eml file at a provided file path and return a
// pre-filled Msg pointer
func EMLToMsg(fp string) (*Msg, error) {
m := &Msg{
addrHeader: make(map[AddrHeader][]*nm.Address),
genHeader: make(map[Header][]string),
preformHeader: make(map[Header]string),
mimever: MIME10,
}
pm, mbbuf, err := readEML(fp)
if err != nil || pm == nil {
return m, fmt.Errorf("failed to parse EML file: %w", err)
}
if err := parseEMLHeaders(&pm.Header, m); err != nil {
return m, fmt.Errorf("failed to parse EML headers: %w", err)
}
if err := parseEMLBodyParts(pm, mbbuf, m); err != nil {
return m, fmt.Errorf("failed to parse EML body parts: %w", err)
}
return m, nil
}
// readEML opens an EML file and uses net/mail to parse the header and body
func readEML(fp string) (*nm.Message, *bytes.Buffer, error) {
fh, err := os.Open(fp)
if err != nil {
return nil, nil, fmt.Errorf("failed to open EML file: %w", err)
}
defer func() {
_ = fh.Close()
}()
pm, err := nm.ReadMessage(fh)
if err != nil {
return pm, nil, fmt.Errorf("failed to parse EML: %w", err)
}
buf := bytes.Buffer{}
if _, err = buf.ReadFrom(pm.Body); err != nil {
return nil, nil, err
}
return pm, &buf, nil
}
// parseEMLHeaders will check the EML headers for the most common headers and set the
// according settings in the Msg
func parseEMLHeaders(mh *nm.Header, m *Msg) error {
commonHeaders := []Header{
HeaderContentType, HeaderImportance, HeaderInReplyTo, HeaderListUnsubscribe,
HeaderListUnsubscribePost, HeaderMessageID, HeaderMIMEVersion, HeaderOrganization,
HeaderPrecedence, HeaderPriority, HeaderReferences, HeaderSubject, HeaderUserAgent,
HeaderXMailer, HeaderXMSMailPriority, HeaderXPriority,
}
// Extract address headers
if v := mh.Get(HeaderFrom.String()); v != "" {
if err := m.From(v); err != nil {
return fmt.Errorf(`failed to parse "From:" header: %w`, err)
}
}
ahl := map[AddrHeader]func(...string) error{
HeaderTo: m.To,
HeaderCc: m.Cc,
HeaderBcc: m.Bcc,
}
for h, f := range ahl {
if v := mh.Get(h.String()); v != "" {
var als []string
pal, err := nm.ParseAddressList(v)
if err != nil {
return fmt.Errorf(`failed to parse address list: %w`, err)
}
for _, a := range pal {
als = append(als, a.String())
}
if err := f(als...); err != nil {
return fmt.Errorf(`failed to parse "To:" header: %w`, err)
}
}
}
// Extract date from message
d, err := mh.Date()
if err != nil {
switch {
case errors.Is(err, nm.ErrHeaderNotPresent):
m.SetDate()
default:
return fmt.Errorf("failed to parse EML date: %w", err)
}
}
if err == nil {
m.SetDateWithValue(d)
}
// Extract common headers
for _, h := range commonHeaders {
if v := mh.Get(h.String()); v != "" {
m.SetGenHeader(h, v)
}
}
return nil
}
// parseEMLBodyParts ...
func parseEMLBodyParts(pm *nm.Message, mbbuf *bytes.Buffer, m *Msg) error {
// Extract the transfer encoding of the body
mt, par, err := mime.ParseMediaType(pm.Header.Get(HeaderContentType.String()))
if err != nil {
return fmt.Errorf("failed to extract content type: %w", err)
}
if v, ok := par["charset"]; ok {
m.SetCharset(Charset(v))
}
if cte := pm.Header.Get(HeaderContentTransferEnc.String()); cte != "" {
switch strings.ToLower(cte) {
case NoEncoding.String():
m.SetEncoding(NoEncoding)
}
}
switch strings.ToLower(mt) {
case TypeTextPlain.String():
m.SetBodyString(TypeTextPlain, mbbuf.String())
default:
}
return nil
}