[mail/mime] Fix content-type has invalid characters in field value. Fix #7503

[Maks3w]

This bug has been introduced in v2.4.1 due the security patch ZF2015-04 for to prevent CRLF injection.

Zend\Mime\Part line was originally introduced in ZF1@583 with the following commit message

• Correctly handle multipart/alternative to close Service\Amazon: SimpleDb and Authentication services ported #59:
  • If both text and html body present, create multipart/alternative part
  • If text, html, and attachments are present, create multipart/alternative
    part for text+html, but mark email as multipart/mixed
• Note: Zend_Mime::LINEEND as \r\n is causing issues on multipart emails (too
  many line breaks); switching to \n fixes the issue, but doesn't follow
  standards. Need reviewers.

Zend_Mime::LINEEND was replaced by $EOL argument on ZF1@598 with the following commit message

• Refactoring of Zend_Mail/Zend_Mime; mail message construction happens in
  transport. Fixes Parse Error: T_OBJECT_OPERATOR in \Zend\Tool\Framework\Client\Console\Manifest.php #134 and [Zend_Application] Incorrect number of Arguments in calling registerNamespace #106.

RFC 2045 section 5.1 defines the syntax of Content-Type Header field as this (only relevant parts of the syntax posted):

In the Augmented BNF notation of RFC 822, a Content-Type header field
value is defined as follows:

content := "Content-Type" ":" type "/" subtype
           *(";" parameter)
           ; Matching of media type and subtype
           ; is ALWAYS case-insensitive.

parameter := attribute "=" value

attribute := token
             ; Matching of attributes
             ; is ALWAYS case-insensitive.

value := token / quoted-string

token := 1*<any (US-ASCII) CHAR except SPACE, CTLs,
         or tspecials>

tspecials :=  "(" / ")" / "<" / ">" / "@" /
              "," / ";" / ":" / "\" / <">
              "/" / "[" / "]" / "?" / "="
              ; Must be in quoted-string,
              ; to use within parameter values

Finally on ZF2 has been duplicated the same behavior on Zend\Mail\Header\ContentType

297ba86#diff-78a765eeca5dcb0c4d8fa594675622f6R76

[Maks3w]

Seems to break each parameter in his own line is just a cosmetic change for pretty print the header using the header folding feature.

Fix:

• Generation of headers with EOL in Zend\Mime\Part

Don't fix:

• Generation of headers with EOL in Zend\Mail\Headers\Content-type
• Headers with folding sequences when call HeaderInterface::fromString()

[weierophinney]

Just a note for those coming to this issue: ContentType currently uses Headers::FOLDING, and not a hard-coded inline sequence: https://github.com/zendframework/zf2/blob/master/library/Zend/Mail/Header/ContentType.php#L72

[weierophinney]

Why have a return statement at all?