Reading multipart content from raw http request

user517406 picture user517406 · Jan 7, 2014 · Viewed 25.9k times · Source

I am saving a raw HTTP request to a text file and I need to read the multipart content within it. I know there are a number of 3rd party tools to do this but I need to do this with the .NET framework if possible. I have tried reading the txt file into a stream but I don't know how to extract the multipart content. Here is an example of the code I have been using and a sample file I am trying to read from :

    var content = new MultipartFormDataContent();

            var stream = new StreamContent(File.Open(@"C:\temp\test.txt", FileMode.Open));
            content.Add(stream);

            List<StreamContent> lstStreamContents = new List<StreamContent>();

            if (content != null)
            {
                if (content.IsMimeMultipartContent())
                    await content.ReadAsMultipartAsync(StreamProvider);

                foreach (MultipartContent multiPartContent in content)
                {
                    foreach (var streamContent in multiPartContent).....

Text file :

Cache-Control: no-cache
Connection: Close
Content-Length: 5216
Content-Type: multipart/related;
     boundary="cbsms-main-boundary";
     start="<soap-envelope>", text/xml;
     charset=utf-8
Accept: */*
Host: hostname
User-Agent: Mozilla/4.0 (compatible; Win32; WinHttp.WinHttpRequest.5)
soapaction: ""

This is a multi-part message in MIME format.

--cbsms-main-boundary
Content-Type: text/xml;
     charset="utf-8"
Content-ID: <soap-envelope>

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
<SOAP-ENV:Header>
<mm7:TransactionID
xmlns:mm7="http://www.3gpp.org/ftp/Specs/archive/23_series/23.140/schema/REL
-6-MM7-1-2">5947CCE35D5B4AEFB99DADDDF9472E67</mm7:TransactionID>
</SOAP-ENV:Header>
<SOAP-ENV:Body>
<mm7:DeliverReq
xmlns:mm7="http://www.3gpp.org/ftp/Specs/archive/23_series/23.140/schema/REL
-6-MM7-1-2">
<mm7:MM7Version>6.5.0</mm7:MM7Version>
<mm7:MMSRelayServerID>hostname</mm7:MMSRelayServerID>
<mm7:LinkedID>1-1754394156</mm7:LinkedID>
<mm7:SenderAddress>
<mm7:Number>46707630767</mm7:Number>
</mm7:SenderAddress>
<mm7:Recipients>
<mm7:To>
<mm7:Number>72401</mm7:Number>
</mm7:To>
</mm7:Recipients>
<mm7:TimeStamp>2008-05-08 11:16:39</mm7:TimeStamp> <mm7:Priority>Normal</mm7:Priority>
<mm7:Subject>Tube test</mm7:Subject>
</mm7:DeliverReq>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

--cbsms-main-boundary
Content-Type: multipart/mixed;
     boundary="cbsms-sub-boundary"
Content-ID: <MM7-Media>

--cbsms-sub-boundary
content-type: application/smil;
    Name=main.smil;Charset=utf-8
content-transfer-encoding: 7bit
content-id: <AAAA>
content-length: 483

<smil><head><layout><root-layout backgroundColor="#FFFFFF"
background-color="#FFFFFF" height="480px" width="640px"/> <region id="Image" top="0" left="0" height="50%" width="100%" fit="meet"/> <region id="Text" top="50%" left="0" height="50%" width="100%"
fit="scroll"/>
</layout>
</head>
<body><par dur="4000ms"><img src="smslogo.jpg" region="Image"></img> <text src="smil.txt" region="Text"><param name="foreground-color"
value="#000000"/>
</text>
</par>
</body>
</smil>

--cbsms-sub-boundary
content-type: image/jpeg;
    Name=smslogo.jpg
content-transfer-encoding: Base64
content-location: smslogo.jpg
content-length: 2218

/9j/4AAQSkZJRgABAgAAZABkAAD/7AARRHVja3kAAQAEAAAAKgAA/+4ADkFkb2JlAGTAAAAA
Af/bAIQACwgICAgICwgICxAKCQoQEw4LCw4TFhERExERFhUREhISEhEVFRkaGxoZFSEhJCQh
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AQEAAAAAAAAAAAAAAAUAAQIEBgcDAQEBAQEBAAAAAAAAAAAAAAABAAIDBBAAAQMCAwQDCgkK
BwAAAAAAAQACAxEEIRIFMVETBkFhgXGRsSJCYrKT0xSh0TJScpIjMxbB4YKiJBUlNVUX8NJT
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OD//2Q==

--cbsms-sub-boundary
content-type: text/plain;
    Name=smil.txt;Charset=utf-8
content-transfer-encoding: 7bit
content-location: smil.txt
content-length: 9

Tube test
--cbsms-sub-boundary--

--cbsms-main-boundary--

At the moment I am getting this error 'Unable to cast object of type 'System.Net.Http.StreamContent' to type 'System.Net.Http.MultipartContent'.'

EDIT :

foreach (var part in multipart.Contents)
            {
                if (part.Headers.ContentType.MediaType == "multipart/mixed")
                {
                    if (part.IsMimeMultipartContent())
                        await part.ReadAsMultipartAsync(StreamProvider);

                    foreach (MultipartContent multiPartContent in StreamProvider.Contents)
                    {

This gives the error ''Unexpected end of MIME multipart stream. MIME multipart message is not complete'

Answer

Anton Tykhyy picture Anton Tykhyy · Jan 7, 2014

You are adding a StreamContent as a part to the empty MultipartFormDataContent. Naturally, ReadAsMultipartAsync then does nothing. Instead, you want to read the StreamContent. Also, your file contains not just the content, but the headers as well. If you snip off the headers, this ought to work:

using (var stream = File.Open (@"C:\temp\test.txt", FileMode.Open))
{
    // note: StreamContent has no Content-Type set by default
    // set a suitable Content-Type for ReadAsMultipartAsync()
    var content = new StreamContent (stream) ;
    content.Headers.ContentType = 
        System.Net.Http.Headers.MediaTypeHeaderValue.Parse (
            "multipart/related; boundary=cbsms-main-boundary") ;

    // TODO: make this recursive if required...
    var outerMultipart = await stream.ReadAsMultipartAsync () ;

    foreach (var outerPart in outerMultipart.Contents)
    {
        if (outerPart.IsMimeMultipartContent())
        {
            var innerMultipart = await outerPart.ReadAsMultipartAsync () ;

            foreach (var innerPart in innerMultipart.Contents) // do stuff
        }
        else // do other stuff
    }
}