DataFlex

Count the DKIM Signatures in a Message

Demonstrates the Chilkat Dkim.NumDkimSigs method, which returns the number of DKIM-Signature header fields in a MIME message. The only argument is a BinData holding the complete MIME.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: A message can legitimately carry several DKIM signatures — the original sender's plus ones added by forwarders or mailing lists — so a verifier needs to know how many there are before checking each. This count is what supplies the valid index range for DkimVerify. Note that it counts header fields by name only, without validating them, so a malformed DKIM-Signature field is still included in the total.

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoDkim
    Variant vMimeData
    Handle hoMimeData
    Integer iNumSigs
    String sTemp1

    Move False To iSuccess

    //  Demonstrates the Dkim.NumDkimSigs method, which returns the number of DKIM-Signature header
    //  fields in a MIME message.  The only argument is a BinData holding the complete MIME.

    Get Create (RefClass(cComChilkatDkim)) To hoDkim
    If (Not(IsComObjectCreated(hoDkim))) Begin
        Send CreateComObject of hoDkim
    End

    //  Load the complete MIME message.
    Get Create (RefClass(cComChilkatBinData)) To hoMimeData
    If (Not(IsComObjectCreated(hoMimeData))) Begin
        Send CreateComObject of hoMimeData
    End
    Get ComLoadFile Of hoMimeData "qa_data/received.eml" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoMimeData To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Count the DKIM-Signature header fields.  The count includes malformed signatures, since the
    //  fields are counted without validating their syntax.
    Get pvComObject of hoMimeData to vMimeData
    Get ComNumDkimSigs Of hoDkim vMimeData To iNumSigs
    Showln "The message has " iNumSigs " DKIM-Signature header(s)."


End_Procedure