func read_message(r io.Reader) (NNTPMessage, error) {
msg, err := mail.ReadMessage(r)
var nntp nntpArticle
if err == nil {
nntp.headers = ArticleHeaders(msg.Header)
content_type := nntp.ContentType()
media_type, params, err := mime.ParseMediaType(content_type)
if err != nil {
log.Println("failed to parse media type", err, "for mime", content_type)
return nil, err
}
boundary, ok := params["boundary"]
if ok {
partReader := multipart.NewReader(msg.Body, boundary)
for {
part, err := partReader.NextPart()
if err == io.EOF {
return nntp, nil
} else if err == nil {
hdr := part.Header
// get content type of part
part_type := hdr.Get("Content-Type")
// parse content type
media_type, _, err = mime.ParseMediaType(part_type)
if err == nil {
if media_type == "text/plain" {
att := readAttachmentFromMimePart(part)
if att != nil {
nntp.message = att.(nntpAttachment)
nntp.message.header.Set("Content-Type", part_type)
}
} else {
// non plaintext gets added to attachments
att := readAttachmentFromMimePart(part)
if att != nil {
nntp = nntp.Attach(att).(nntpArticle)
}
}
} else {
log.Println("part has no content type", err)
}
part.Close()
} else {
log.Println("failed to load part! ", err)
return nil, err
}
}
} else if media_type == "message/rfc822" {
// tripcoded message
sig := nntp.headers.Get("X-Signature-Ed25519-Sha512", "")
pk := nntp.Pubkey()
if pk == "" || sig == "" {
log.Println("invalid sig or pubkey", sig, pk)
return nil, errors.New("invalid headers")
}
log.Printf("got signed message from %s", pk)
pk_bytes := unhex(pk)
sig_bytes := unhex(sig)
r := bufio.NewReader(msg.Body)
crlf := []byte{13, 10}
for {
line, err := r.ReadBytes('\n')
if err == io.EOF {
break
}
nntp.signedPart.body.Write(line[:len(line)-1])
nntp.signedPart.body.Write(crlf)
}
if nntp.signedPart.body.Len() < 2 {
log.Println("signed body is too small")
} else {
body := nntp.signedPart.body.Bytes()[:nntp.signedPart.body.Len()-2]
body_hash := sha512.Sum512(body)
log.Printf("hash=%s", hexify(body_hash[:]))
if nacl.CryptoVerifyFucky(body_hash[:], sig_bytes, pk_bytes) {
log.Println("signature is valid :^)")
return nntp, nil
} else {
log.Println("!!!signature is invalid!!!")
}
}
} else {
// plaintext attachment
var buff bytes.Buffer
_, err = io.Copy(&buff, msg.Body)
nntp.message = createPlaintextAttachment(buff.String())
return nntp, err
}
} else {
log.Println("failed to read message", err)
return nil, err
}
return nntp, err
}