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Refactor multipart parsing in eml.go

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The code is refactored to improve multipart parsing in EML. The `parseEMLMultipartAlternative` function is updated to `parseEMLMultipart` for more general utilization. This involves iterating through the parts of a multipart message until content disposition is found and appended. A new function `parseMultiPartHeader` is introduced to parse multipart header and handle charset more sensibly.
This commit is contained in:
Winni Neessen 2024-06-19 13:57:00 +02:00
parent 29305675d6
commit 85c07c22cc
Signed by: wneessen
GPG key ID: 5F3AF39B820C119D
1 changed files with 35 additions and 25 deletions
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60
eml.go
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@ -184,8 +184,8 @@ func parseEMLBodyParts(parsedMsg *netmail.Message, bodybuf *bytes.Buffer, msg *M
return fmt.Errorf("failed to parse plain body: %w", err)
}
case strings.EqualFold(mediatype, TypeMultipartAlternative.String()),
strings.EqualFold(mediatype, "multipart/mixed"):
if err = parseEMLMultipartAlternative(params, bodybuf, msg); err != nil {
strings.EqualFold(mediatype, TypeMultipartMixed.String()):
if err = parseEMLMultipart(params, bodybuf, msg); err != nil {
return fmt.Errorf("failed to parse multipart/alternative body: %w", err)
}
default:
@ -224,8 +224,8 @@ func parseEMLBodyPlain(mediatype string, parsedMsg *netmail.Message, bodybuf *by
return fmt.Errorf("unsupported Content-Transfer-Encoding")
}
// parseEMLMultipartAlternative parses a multipart/alternative body part of a EML
func parseEMLMultipartAlternative(params map[string]string, bodybuf *bytes.Buffer, msg *Msg) error {
// parseEMLMultipart parses a multipart body part of a EML
func parseEMLMultipart(params map[string]string, bodybuf *bytes.Buffer, msg *Msg) error {
boundary, ok := params["boundary"]
if !ok {
return fmt.Errorf("no boundary tag found in multipart body")
@ -236,6 +236,16 @@ func parseEMLMultipartAlternative(params map[string]string, bodybuf *bytes.Buffe
return fmt.Errorf("failed to get next part of multipart message: %w", err)
}
for err == nil {
if contentDisposition, ok := multiPart.Header[HeaderContentDisposition.String()]; ok {
cdType, optional := parseMultiPartHeader(contentDisposition[0])
fmt.Println("CTD:", cdType)
fmt.Printf("optional: %+v\n", optional)
if err = msg.AttachReader("", multiPart); err != nil {
return fmt.Errorf("failed to attach multipart body: %w", err)
}
return nil
}
multiPartData, mperr := io.ReadAll(multiPart)
if mperr != nil {
_ = multiPart.Close()
@ -246,9 +256,11 @@ func parseEMLMultipartAlternative(params map[string]string, bodybuf *bytes.Buffe
if !ok {
return fmt.Errorf("failed to get content-type from part")
}
contentType, charSet := parseContentType(multiPartContentType[0])
p := msg.newPart(ContentType(contentType))
p.SetCharset(Charset(charSet))
contentType, optional := parseMultiPartHeader(multiPartContentType[0])
part := msg.newPart(ContentType(contentType))
if charset, ok := optional["charset"]; ok {
part.SetCharset(Charset(charset))
}
mutliPartTransferEnc, ok := multiPart.Header[HeaderContentTransferEnc.String()]
if !ok {
@ -260,16 +272,16 @@ func parseEMLMultipartAlternative(params map[string]string, bodybuf *bytes.Buffe
switch {
case strings.EqualFold(mutliPartTransferEnc[0], EncodingB64.String()):
if err := handleEMLMultiPartBase64Encoding(multiPartData, p); err != nil {
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()):
p.SetContent(string(multiPartData))
part.SetContent(string(multiPartData))
default:
return fmt.Errorf("unsupported Content-Transfer-Encoding")
}
msg.parts = append(msg.parts, p)
msg.parts = append(msg.parts, part)
multiPart, err = multipartReader.NextPart()
}
if !errors.Is(err, io.EOF) {
@ -296,9 +308,9 @@ func parseEMLEncoding(mailHeader *netmail.Header, msg *Msg) {
// parseEMLContentTypeCharset parses and determines the charset and content type of the message
func parseEMLContentTypeCharset(mailHeader *netmail.Header, msg *Msg) {
if value := mailHeader.Get(HeaderContentType.String()); value != "" {
contentType, charSet := parseContentType(value)
if charSet != "" {
msg.SetCharset(Charset(charSet))
contentType, optional := parseMultiPartHeader(value)
if charset, ok := optional["charset"]; ok {
msg.SetCharset(Charset(charset))
}
msg.setEncoder()
if contentType != "" {
@ -318,18 +330,16 @@ func handleEMLMultiPartBase64Encoding(multiPartData []byte, part *Part) error {
return nil
}
// parseContentType parses the Content-Type header and returns the type and charse as
// separate string values
func parseContentType(contentTypeHeader string) (contentType string, charSet string) {
contentTypeSplit := strings.SplitN(contentTypeHeader, "; ", 2)
if len(contentTypeSplit) != 2 {
return
}
contentType = contentTypeSplit[0]
if strings.HasPrefix(strings.ToLower(contentTypeSplit[1]), "charset=") {
charSetSplit := strings.SplitN(contentTypeSplit[1], "=", 2)
if len(charSetSplit) == 2 {
charSet = charSetSplit[1]
// parseMultiPartHeader parses a multipart header and returns the value and optional parts as
// separate map
func parseMultiPartHeader(multiPartHeader string) (header string, optional map[string]string) {
optional = make(map[string]string)
headerSplit := strings.SplitN(multiPartHeader, "; ", 2)
header = headerSplit[0]
if len(headerSplit) == 2 {
optSplit := strings.SplitN(headerSplit[1], "=", 2)
if len(optSplit) == 2 {
optional[optSplit[0]] = optSplit[1]
}
}
return