在StreamReader中搜索base64编码的内容？

Question

I need to parse a NDR file from an SMTP badmail folder from IIS. Attached to the NDR is the content which is base64 encoded. That is what I need to get to. I was hoping that, using a StreamReader, it would be all one line, but they are separate lines when a perforam a .ReadLine.

Here is a sample of an NDR:

From: postmaster
To: hidden
Date: Thu, 12 Nov 2009 11:56:14 -0500
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
    boundary="9B095B5ADSN=_01CA638BF4740C5500000045spinstitch.com"
X-DSNContext: 7ce717b1 - 1378 - 00000002 - C00402EF
Message-ID: 
Subject: Delivery Status Notification (Failure)

This is a MIME-formatted message.  
Portions of this message may be unreadable without a MIME-capable mail program.

--9B095B5ADSN=_01CA638BF4740C5500000045spinstitch.com
Content-Type: text/plain; charset=unicode-1-1-utf-7

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

       hidden




--9B095B5ADSN=_01CA638BF4740C5500000045spinstitch.com
Content-Type: message/delivery-status

Reporting-MTA: dns;spinstitch.com
Received-From-MTA: dns;spinstitch
Arrival-Date: Thu, 12 Nov 2009 11:56:11 -0500

Final-Recipient: rfc822;hidden
Action: failed
Status: 5.4.0

--9B095B5ADSN=_01CA638BF4740C5500000045spinstitch.com
Content-Type: message/rfc822

Received: from mail pickup service by spinstitch.com with Microsoft SMTPSVC;
     Thu, 12 Nov 2009 11:56:11 -0500
MIME-Version: 1.0
From: hidden
To: hidden
Date: 12 Nov 2009 11:56:11 -0500
Subject: For Sale: 463 Saltaire Dr. Calabash, NC US  28467 $6,800,000
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: base64
Message-ID: 
X-OriginalArrivalTime: 12 Nov 2009 16:56:11.0813 (UTC) FILETIME=[09CED550:01CA63B9]

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--9B095B5ADSN=_01CA638BF4740C5500000045spinstitch.com--

Answer 1

This regular expression matches your base64 string and decode it:

Match m = Regex.Match(
    File.ReadAllText(@"c:\edit1.txt"),
    @"X-OriginalArrivalTime:.*?\r\n\r\n([\s\S]*)\r\n\r\n");
byte[] data = Convert.FromBase64String(m.Groups[1].Value);

If you prefer do not to use regular expressions, you could try to skip every line until you find that X-OriginalArrivalTime header. From there, you can keep every line until you find an empty line, or stream end.

Answer 2

尝试改用Read（）方法。