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Add support for 7bit and 8bit encodings in EML parsing

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Enhanced EML parsing to handle 7bit and 8bit content transfer encodings. Updated related test cases to verify the correct handling of these encodings. This ensures compliance with RFC2045 for defaulting to 7bit when no encoding is specified.
This commit is contained in:
Winni Neessen 2024-08-01 10:55:28 +02:00
parent a28cf14efd
commit ed93e51cec
Signed by: wneessen
GPG key ID: 385AC9889632126E
2 changed files with 161 additions and 2 deletions
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18
eml.go
View file

@ -207,6 +207,12 @@ func parseEMLBodyParts(parsedMsg *netmail.Message, bodybuf *bytes.Buffer, msg *M
// parseEMLBodyPlain parses the mail body of plain type mails
func parseEMLBodyPlain(mediatype string, parsedMsg *netmail.Message, bodybuf *bytes.Buffer, msg *Msg) error {
contentTransferEnc := parsedMsg.Header.Get(HeaderContentTransferEnc.String())
// According to RFC2045, if no Content-Transfer-Encoding is set, we can imply 7bit US-ASCII encoding
if contentTransferEnc == "" || strings.EqualFold(contentTransferEnc, EncodingUSASCII.String()) {
msg.SetEncoding(EncodingUSASCII)
msg.SetBodyString(ContentType(mediatype), bodybuf.String())
return nil
}
if strings.EqualFold(contentTransferEnc, NoEncoding.String()) {
msg.SetEncoding(NoEncoding)
msg.SetBodyString(ContentType(mediatype), bodybuf.String())
@ -308,14 +314,22 @@ ReadNextPart:
}
switch {
case strings.EqualFold(mutliPartTransferEnc[0], EncodingUSASCII.String()):
part.SetEncoding(EncodingUSASCII)
part.SetContent(string(multiPartData))
case strings.EqualFold(mutliPartTransferEnc[0], NoEncoding.String()):
part.SetEncoding(NoEncoding)
part.SetContent(string(multiPartData))
case strings.EqualFold(mutliPartTransferEnc[0], EncodingB64.String()):
if err := handleEMLMultiPartBase64Encoding(multiPartData, part); err != nil {
part.SetEncoding(EncodingB64)
if err = handleEMLMultiPartBase64Encoding(multiPartData, part); err != nil {
return fmt.Errorf("failed to handle multipart base64 transfer-encoding: %w", err)
}
case strings.EqualFold(mutliPartTransferEnc[0], EncodingQP.String()):
part.SetEncoding(EncodingQP)
part.SetContent(string(multiPartData))
default:
return fmt.Errorf("unsupported Content-Transfer-Encoding")
return fmt.Errorf("unsupported Content-Transfer-Encoding: %s", mutliPartTransferEnc[0])
}
msg.parts = append(msg.parts, part)

145
eml_test.go
View file

@ -32,6 +32,29 @@ This is a test mail. Please do not reply to this. Also this line is very long so
should be wrapped.
Thank your for your business!
The go-mail team
--
This is a signature`
exampleMailPlain7Bit = `Date: Wed, 01 Nov 2023 00:00:00 +0000
MIME-Version: 1.0
Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
Subject: Example mail // plain text without encoding
User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
From: "Toni Tester" <go-mail@go-mail.dev>
To: <go-mail+test@go-mail.dev>
Cc: <go-mail+cc@go-mail.dev>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Dear Customer,
This is a test mail. Please do not reply to this. Also this line is very long so it
should be wrapped.
Thank your for your business!
The go-mail team
@ -525,6 +548,72 @@ hw22iFHl7YlpOmedZvtMTfQffXeXnvI+rTKNxguyvDKvB7U4qQAAAAlwSFlzAAALEwAACxMBAJqc
GAAAABFJREFUCJljnMoAA0wMNGcCAEQrAKk9oHKhAAAAAElFTkSuQmCC
--fe785e0384e2607697cc2ecb17cce003003bb7ca9112104f3e8ce727edb5--`
exampleMultiPart7BitBase64 = `Date: Wed, 01 Nov 2023 00:00:00 +0000
MIME-Version: 1.0
Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
Subject: Example mail // 7bit with base64 attachment
User-Agent: go-mail v0.4.1 // https://github.com/wneessen/go-mail
X-Mailer: go-mail v0.4.1 // https://github.com/wneessen/go-mail
From: "Toni Tester" <go-mail@go-mail.dev>
To: <go-mail+test@go-mail.dev>
Cc: <go-mail+cc@go-mail.dev>
Content-Type: multipart/mixed;
boundary="------------26A45336F6C6196BD8BBA2A2"
This is a multi-part message in MIME format.
--------------26A45336F6C6196BD8BBA2A2
Content-Type: text/plain; charset=US-ASCII; format=flowed
Content-Transfer-Encoding: 7bit
testtest
testtest
testtest
testtest
testtest
testtest
--------------26A45336F6C6196BD8BBA2A2
Content-Type: text/plain; charset=UTF-8;
name="testfile.txt"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
filename="testfile.txt"
VGhpcyBpcyBhIHRlc3QgaW4gQmFzZTY0
--------------26A45336F6C6196BD8BBA2A2--`
exampleMultiPart8BitBase64 = `Date: Wed, 01 Nov 2023 00:00:00 +0000
MIME-Version: 1.0
Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
Subject: Example mail // 8bit with base64 attachment
User-Agent: go-mail v0.4.1 // https://github.com/wneessen/go-mail
X-Mailer: go-mail v0.4.1 // https://github.com/wneessen/go-mail
From: "Toni Tester" <go-mail@go-mail.dev>
To: <go-mail+test@go-mail.dev>
Cc: <go-mail+cc@go-mail.dev>
Content-Type: multipart/mixed;
boundary="------------26A45336F6C6196BD8BBA2A2"
This is a multi-part message in MIME format.
--------------26A45336F6C6196BD8BBA2A2
Content-Type: text/plain; charset=US-ASCII; format=flowed
Content-Transfer-Encoding: 8bit
testtest
testtest
testtest
testtest
testtest
testtest
--------------26A45336F6C6196BD8BBA2A2
Content-Type: text/plain; charset=UTF-8;
name="testfile.txt"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
filename="testfile.txt"
VGhpcyBpcyBhIHRlc3QgaW4gQmFzZTY0
--------------26A45336F6C6196BD8BBA2A2--`
)
func TestEMLToMsgFromString(t *testing.T) {
@ -534,6 +623,10 @@ func TestEMLToMsgFromString(t *testing.T) {
enc string
sub string
}{
{
"Plain text no encoding (7bit)", exampleMailPlain7Bit, "7bit",
"Example mail // plain text without encoding",
},
{
"Plain text no encoding", exampleMailPlainNoEnc, "8bit",
"Example mail // plain text without encoding",
@ -866,6 +959,58 @@ func TestEMLToMsgFromStringMultipartMixedAlternativeRelated(t *testing.T) {
}
}
func TestEMLToMsgFromStringMultipartMixedWith7Bit(t *testing.T) {
wantSubject := "Example mail // 7bit with base64 attachment"
msg, err := EMLToMsgFromString(exampleMultiPart7BitBase64)
if err != nil {
t.Errorf("EML multipart mixed with 7bit: %s", err)
}
if subject := msg.GetGenHeader(HeaderSubject); len(subject) > 0 && !strings.EqualFold(subject[0], wantSubject) {
t.Errorf("EMLToMsgFromString of EML multipart mixed with 7bit: expected subject: %s,"+
" but got: %s", wantSubject, subject[0])
}
if len(msg.parts) != 1 {
t.Errorf("EMLToMsgFromString of EML multipart mixed with 7bit failed: expected 1 part, got: %d",
len(msg.parts))
return
}
if !strings.EqualFold(msg.parts[0].GetEncoding().String(), EncodingUSASCII.String()) {
t.Errorf("EMLToMsgFromString of EML multipart mixed with 7bit failed: expected encoding: %s, got %s",
EncodingUSASCII.String(), msg.parts[0].GetEncoding().String())
}
if len(msg.attachments) != 1 {
t.Errorf("EMLToMsgFromString of EML multipart mixed with 7bit failed: expected 1 attachment, got: %d",
len(msg.attachments))
return
}
}
func TestEMLToMsgFromStringMultipartMixedWith8Bit(t *testing.T) {
wantSubject := "Example mail // 8bit with base64 attachment"
msg, err := EMLToMsgFromString(exampleMultiPart8BitBase64)
if err != nil {
t.Errorf("EML multipart mixed with 8bit: %s", err)
}
if subject := msg.GetGenHeader(HeaderSubject); len(subject) > 0 && !strings.EqualFold(subject[0], wantSubject) {
t.Errorf("EMLToMsgFromString of EML multipart mixed with 8bit: expected subject: %s,"+
" but got: %s", wantSubject, subject[0])
}
if len(msg.parts) != 1 {
t.Errorf("EMLToMsgFromString of EML multipart mixed with 8bit failed: expected 1 part, got: %d",
len(msg.parts))
return
}
if !strings.EqualFold(msg.parts[0].GetEncoding().String(), NoEncoding.String()) {
t.Errorf("EMLToMsgFromString of EML multipart mixed with 8bit failed: expected encoding: %s, got %s",
NoEncoding.String(), msg.parts[0].GetEncoding().String())
}
if len(msg.attachments) != 1 {
t.Errorf("EMLToMsgFromString of EML multipart mixed with 8bit failed: expected 1 attachment, got: %d",
len(msg.attachments))
return
}
}
// stringToTempFile is a helper method that will create a temporary file form a give data string
func stringToTempFile(data, name string) (string, string, error) {
tempDir, err := os.MkdirTemp("", fmt.Sprintf("*-%s", name))