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