add vendoring

vendor/github.com/jhillyerd/enmime/detect.go

@@ -0,0 +1,94 @@
+package enmime
+
+import (
+	"net/textproto"
+	"strings"
+
+	"github.com/jhillyerd/enmime/mediatype"
+)
+
+// detectMultipartMessage returns true if the message has a recognized multipart Content-Type header
+func detectMultipartMessage(root *Part, multipartWOBoundaryAsSinglepart bool) bool {
+	// Parse top-level multipart
+	ctype := root.Header.Get(hnContentType)
+	mtype, params, _, err := mediatype.Parse(ctype)
+	if err != nil {
+		return false
+	}
+
+	if boundary := params[hpBoundary]; multipartWOBoundaryAsSinglepart && boundary == "" {
+		return false
+	}
+
+	// According to rfc2046#section-5.1.7 all other multipart should
+	// be treated as multipart/mixed
+	return strings.HasPrefix(mtype, ctMultipartPrefix)
+}
+
+// detectAttachmentHeader returns true, if the given header defines an attachment. First it checks
+// if the Content-Disposition header defines either an attachment part or an inline part with at
+// least one parameter. If this test is false, the Content-Type header is checked for attachment,
+// but not inline. Email clients use inline for their text bodies.
+//
+// Valid Attachment-Headers:
+//
+//  - Content-Disposition: attachment; filename="frog.jpg"
+//  - Content-Disposition: inline; filename="frog.jpg"
+//  - Content-Type: attachment; filename="frog.jpg"
+func detectAttachmentHeader(header textproto.MIMEHeader) bool {
+	mtype, params, _, _ := mediatype.Parse(header.Get(hnContentDisposition))
+	if strings.ToLower(mtype) == cdAttachment ||
+		(strings.ToLower(mtype) == cdInline && len(params) > 0) {
+		return true
+	}
+
+	mtype, _, _, _ = mediatype.Parse(header.Get(hnContentType))
+	return strings.ToLower(mtype) == cdAttachment
+}
+
+// detectTextHeader returns true, if the the MIME headers define a valid 'text/plain' or 'text/html'
+// part.  If the emptyContentTypeIsPlain argument is set to true, a missing Content-Type header will
+// result in a positive plain part detection.
+func detectTextHeader(header textproto.MIMEHeader, emptyContentTypeIsText bool) bool {
+	ctype := header.Get(hnContentType)
+	if ctype == "" && emptyContentTypeIsText {
+		return true
+	}
+
+	if mtype, _, _, err := mediatype.Parse(ctype); err == nil {
+		switch mtype {
+		case ctTextPlain, ctTextHTML:
+			return true
+		}
+	}
+
+	return false
+}
+
+// detectBinaryBody returns true if the mail header defines a binary body.
+func detectBinaryBody(root *Part) bool {
+	if detectTextHeader(root.Header, true) {
+		// It is text/plain, but an attachment.
+		// Content-Type: text/plain; name="test.csv"
+		// Content-Disposition: attachment; filename="test.csv"
+		// Check for attachment only, or inline body is marked
+		// as attachment, too.
+		mtype, _, _, _ := mediatype.Parse(root.Header.Get(hnContentDisposition))
+		return strings.ToLower(mtype) == cdAttachment
+	}
+
+	isBin := detectAttachmentHeader(root.Header)
+	if !isBin {
+		// This must be an attachment, if the Content-Type is not
+		// 'text/plain' or 'text/html'.
+		// Example:
+		// Content-Type: application/pdf; name="doc.pdf"
+		mtype, _, _, _ := mediatype.Parse(root.Header.Get(hnContentType))
+		mtype = strings.ToLower(mtype)
+		if mtype != ctTextPlain && mtype != ctTextHTML {
+			return true
+		}
+	}
+
+	return isBin
+}