Reading multipart content from raw http request

c# mime-types multipartform-data multipart

27,412

Solution 1

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
    }
}

Solution 2

Use HttpContentMultipartExtensions class and ReadAsMultipartAsync method http://msdn.microsoft.com/en-us/library/hh835439%28v=vs.108%29.aspx

Good example is here: http://www.asp.net/web-api/overview/working-with-http/sending-html-form-data,-part-2

27,412

Author by

user517406

Updated on July 11, 2022

Comments

user517406 almost 2 years

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'

user517406 over 10 years

Thanks for the answer, I think that is on the right track, however I cannot set Headers.ContentType for the stream object
user517406 over 10 years

Found the issue, should be referring to content object rather than stream
user517406 over 10 years

Excellent...that gets me 2 content types, "text-xml" and "multipart/mixed"...that enables me to parse the xml, but how would I get the content type "image/jpeg" from within the "multipart/mixed" content?
Anton Tykhyy over 10 years

Um... you just get it? By, you know, looping over multipart.Contents?
user517406 over 10 years

Looping through multipart.Contents gives me 2 parts, text-xml and multipart-mixed. The question I was asking was how do I get the image from the multipart-mixed part. I am not sure how to iterate through the multipart-mixed part to get at image-jpeg. Please see Edit above which explains this
user517406 over 10 years

Figured it out, I needed to set the stream position back to 0
Anton Tykhyy over 10 years

I missed that you had nested multipart contents. You iterate through the inner mixed content the same way as through the outer mixed content, except the headers are parsed for you. Your edit is wrong because again you are not reading the inner multi-part content. See my edit here. You must use the return value of ReadAsMultipartAsync!
Jesse Chisholm almost 6 years

Oddly enough, new MediaTypeHeaderValue("multipart/related; boundary=cbsms-main-boundary") didn't do exactly the same things as MediaTypeHeaderValue.Parse("multipart/related; boundary=cbsms-main-boundary") Apparently the constructor only wants the subtype, the the other attributes. Whereas Parse knows what to do with the other attributes.