SQL Server

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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SQL Server

--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  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.

    DECLARE @dkim int
    EXEC @hr = sp_OACreate 'Chilkat.Dkim', @dkim OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    --  Load the complete MIME message.
    DECLARE @mimeData int
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @mimeData OUT

    EXEC sp_OAMethod @mimeData, 'LoadFile', @success OUT, 'qa_data/received.eml'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @mimeData, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @dkim
        EXEC @hr = sp_OADestroy @mimeData
        RETURN
      END

    --  Count the DKIM-Signature header fields.  The count includes malformed signatures, since the
    --  fields are counted without validating their syntax.
    DECLARE @numSigs int
    EXEC sp_OAMethod @dkim, 'NumDkimSigs', @numSigs OUT, @mimeData


    PRINT 'The message has ' + @numSigs + ' DKIM-Signature header(s).'

    EXEC @hr = sp_OADestroy @dkim
    EXEC @hr = sp_OADestroy @mimeData


END
GO