mirror of
https://git.sr.ht/~rjarry/aerc
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108a8ca1d2
Implement a cleartext function in the cryptoutil package to decrypt an encrypted message to cleartext and construct a valid rfc2822 message. The headers from the decrypt message body will be merged with the original headers to create a fully decrypted message. Implements: https://todo.sr.ht/~rjarry/aerc/238 Signed-off-by: Koni Marti <koni.marti@gmail.com> Tested-by: Jens Grassel <jens@wegtam.com> Reviewed-by: Tim Culverhouse <tim@timculverhouse.com> Acked-by: Robin Jarry <robin@jarry.cc>
69 lines
1.7 KiB
Go
69 lines
1.7 KiB
Go
package cryptoutil
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import (
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"bytes"
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"errors"
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"io"
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"strings"
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"git.sr.ht/~rjarry/aerc/app"
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"git.sr.ht/~rjarry/aerc/lib/rfc822"
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"github.com/emersion/go-message/mail"
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)
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func Cleartext(r io.Reader, header mail.Header) ([]byte, error) {
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msg, err := app.CryptoProvider().Decrypt(
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rfc822.NewCRLFReader(r), app.DecryptKeys)
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if err != nil {
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return nil, errors.New("decrypt error")
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}
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full, err := createMessage(header, msg.Body)
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if err != nil {
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return nil, errors.New("failed to create decrypted message")
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}
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return full, nil
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}
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func createMessage(header mail.Header, body io.Reader) ([]byte, error) {
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e, err := rfc822.ReadMessage(body)
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if err != nil {
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return nil, err
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}
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// copy the header values from the "decrypted body". This should set
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// the correct content type.
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hf := e.Header.Fields()
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for hf.Next() {
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header.Set(hf.Key(), hf.Value())
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}
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ctype, params, err := header.ContentType()
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if err != nil {
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return nil, err
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}
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// in case there remains a multipart/{encrypted,signed} content type,
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// manually correct them to multipart/mixed as a fallback.
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ct := strings.ToLower(ctype)
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if strings.Contains(ct, "multipart/encrypted") ||
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strings.Contains(ct, "multipart/signed") {
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delete(params, "protocol")
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delete(params, "micalg")
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header.SetContentType("multipart/mixed", params)
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}
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// a SingleInlineWriter is sufficient since the "decrypted body"
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// already contains the proper boundaries of the parts; we just want to
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// combine it with the headers.
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var message bytes.Buffer
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w, err := mail.CreateSingleInlineWriter(&message, header)
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if err != nil {
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return nil, err
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}
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if _, err := io.Copy(w, e.Body); err != nil {
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return nil, err
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}
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w.Close()
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return message.Bytes(), nil
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}
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