[Webkit-unassigned] [Bug 158423] New: MHTML: Document not displayed due to incorrect folding whitespace handling

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=158423

            Bug ID: 158423
           Summary: MHTML: Document not displayed due to incorrect folding
                    whitespace handling
    Classification: Unclassified
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: All
                OS: All
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Page Loading
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: horst.reiterer at fabasoft.com
                CC: beidson at apple.com

Created attachment 280599
  --> https://bugs.webkit.org/attachment.cgi?id=280599&action=review
Test Document

Loading the attached MHTML document (test.mht) in WebKit results in an empty document. The underlying problem is that the MHTML parser does not parse folding whitespace correctly.

The initial header is as follows:

MIME-Version: 1.0
Content-Type: multipart/related;
 boundary="----=_NextPart_000_0000_01C12184.8FEC43F0"; type=text/html

The second line of the folded Content-Type header starts with a space rather than a tabulator. In RFC2822, folding whitespace is defined as follows:

FWS             =       ([*WSP CRLF] 1*WSP) /   ; Folding white space
                        obs-FWS

So, the second line may start with a space or a tabulator - the input is correct. However, the parser only handles the tabulator case:

qt/qtwebkit/Source/WebCore/platform/network/MIMEHeader.cpp:
        if (line[0] == '\t') {
             ASSERT(!key.isEmpty());

With the attached patch (qt-everywhere-opensource-5.4.1-html-fws-sp.patch) against the WebKit version that comes with QT 5.4.1, the document is displayed as expected.

As the issue occured in the context of QT, we also reported the issue there:

https://bugreports.qt.io/browse/QTBUG-53869

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