HTTP POST with HttpWebRequest

2019-03-02 09:12发布

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问题:

I'm trying to POST some data as if I was using FORM on HTML site (ContentType = multipart/form-data). The target is amazon's s3. I'm using HttpWebRequest / HttpWebResponse and all seems kind of fine to me, but I still can't fight one problem, I keep getting the error:

<?xml version="1.0" encoding="UTF-8"?>
<Error>
  <Code>InvalidArgument</Code>
  <Message>POST requires exactly one file upload per request.</Message>
  <ArgumentValue>0</ArgumentValue>
  <ArgumentName>file</ArgumentName>
</Error>

it seems to be self-describing, but I really do send the "file" field. I've managed to send a file with no problems through test web-site, the whole post-data seems to be exactly the same. When I "spy" the request via wireshark all the headers and the post data as well - it's there as expected.

Does anyone have any idea, why amazon can not see "file" field?

code used (it's cut a bit to make it more readable):

private void addStringToStream(string buff, Stream s)
{
    var bytes = Encoding.UTF8.GetBytes(buff);
    s.Write(bytes, 0, bytes.Length);

    counter += bytes.Length;
}

private void doPost()
{
    HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);

    request.Method = "POST";
    request.ProtocolVersion = new Version(1, 1);

    request.KeepAlive = true;
    request.AllowAutoRedirect = true;

    request.Headers.Add("Accept-Language", "en-us,en;q=0.5");
    request.Headers.Add("Accept-Encoding", "gzip,deflate");
    request.Headers.Add("Accept-Charset", "ISO-8859-1,utf-8;q=0.7,*;q=0.7");

    request.Accept = "text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5";
    request.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.10) Gecko/20071115 Firefox/2.0.0.10";

    string boundary = "---------------------------317205771417341028";
    request.ContentType = "multipart/form-data; boundary=" + boundary;

    request.SendChunked = false;
    request.Credentials = CredentialCache.DefaultCredentials;
    request.CookieContainer = new CookieContainer();

    request.ContentLength = calculateLength();

    using (Stream s = request.GetRequestStream())
    {
        boundary += "\n";

        string inLineContentH = "Content-Disposition: form-data; name=\"{0}\"";
        string contentH = "Content-Disposition: form-data; name=\"{0}\"" + "\n" + "\n";

        string keyH = "key";

        string aclH = "acl";
        string aclV = "public-read";

        string accessKeyH = "AWSAccessKeyId";
        string accessKeyV = publicKey;

        string policyH = "policy";
        string policyV = this.generatePolicy();

        string signatureH = "signature";
        string signatureV = generateSignature(policyV);

        string fileH = "file";
        string fileContentNameH = "filename=\"{0}\"";
        string contentType2H = "Content-Type: application/octet-stream";

        buff = boundary;
        addStringToStream(buff, s);

        buff = string.Format(contentH, keyH);
        addStringToStream(buff, s);

        buff = keyV + "\n";
        addStringToStream(buff, s);

        /* here are all of the others necessary fields added to stream just as the one above
        no other operations are used, just adding bytes to stream 
        and finally we get to the file: */

        buff = boundary;
        addStringToStream(buff, s);

        buff = string.Format(inLineContentH, fileH) + "; " + string.Format(fileContentNameH, Path.GetFileName(this.FilePath)) + "\n";
        addStringToStream(buff, s);

        buff = contentType2H + "\n" + "\n";
        addStringToStream(buff, s);

        var inStream = File.OpenRead(FilePath);
        int val;
        while ((val = inStream.ReadByte()) != -1)
        {
            s.WriteByte((byte)val);
            counter++;
        }

        buff = "\n";
        addStringToStream(buff, s);

        buff = boundary;
        addStringToStream(buff, s);

        buff = string.Format(contentH, "submit");
        addStringToStream(buff, s);

        buff = "Upload to Amazon S3" + "\n";
        addStringToStream(buff, s);

        buff = boundary.Replace("\r", "").Replace("\n", "") + "--";
        addStringToStream(buff, s);
    }

    request.GetResponse();
}

post data that goes to the stream:

---------------------------317205771417341028
Content-Disposition: form-data; name="key"

webtest/image.png
---------------------------317205771417341028
Content-Disposition: form-data; name="acl"

public-read
---------------------------317205771417341028
Content-Disposition: form-data; name="AWSAccessKeyId"

AKIAJOQLTUC5H2NJ65NA
---------------------------317205771417341028
Content-Disposition: form-data; name="policy"

Oi8vd3d3Lmdvb2dsZS[...]c3QiXSwNCiAgXQ0KfQ0K
---------------------------317205771417341028
Content-Disposition: form-data; name="Signature"

06GBK5DJ71aB[...]M8Ct8JOE=
---------------------------317205771417341028
Content-Disposition: form-data; name="file"; filename="eclipse.png"
Content-Type: application/octet-stream

‰PNG

IHDRn
[...the rest of the image...]
IEND®B‚
---------------------------317205771417341028
Content-Disposition: form-data; name="submit"

Upload to Amazon S3
---------------------------317205771417341028--

and... the wireshark's list:

OUT TCP 58383 > http [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=2 SACK_PERM=1
IN  TCP http > 58383 [SYN, ACK] Seq=0 Ack=1 Win=8190 Len=0 MSS=1460 WS=6 SACK_PERM=1
OUT TCP 58383 > http [ACK] Seq=1 Ack=1 Win=65700 Len=0
OUT TCP [TCP segment of a reassembled PDU]
IN  HTTP    HTTP/1.1 100 Continue 
OUT TCP [TCP segment of a reassembled PDU]
OUT TCP [TCP segment of a reassembled PDU]
OUT TCP [TCP segment of a reassembled PDU]
OUT TCP [TCP segment of a reassembled PDU]
IN  TCP http > 58383 [ACK] Seq=26 Ack=2031 Win=1331456 Len=0
OUT TCP [TCP segment of a reassembled PDU]
OUT TCP [TCP segment of a reassembled PDU]
IN  TCP http > 58383 [ACK] Seq=26 Ack=3969 Win=1337344 Len=0
OUT TCP [TCP segment of a reassembled PDU]
OUT TCP [TCP segment of a reassembled PDU]
IN  TCP http > 58383 [ACK] Seq=26 Ack=6889 Win=1343232 Len=0
OUT TCP [TCP segment of a reassembled PDU]
OUT TCP [TCP segment of a reassembled PDU]
IN  TCP http > 58383 [ACK] Seq=26 Ack=8441 Win=1346048 Len=0
OUT HTTP    POST / HTTP/1.1
//the one above contains the last bytes added to the stream
IN  TCP http > 58383 [ACK] Seq=26 Ack=10225 Win=1348864 Len=0
IN  TCP http > 58383 [ACK] Seq=26 Ack=10857 Win=1351936 Len=0
IN  TCP http > 58383 [ACK] Seq=26 Ack=12162 Win=1354752 Len=0
IN  TCP http > 58383 [ACK] Seq=26 Ack=13622 Win=1357824 Len=0
IN  TCP http > 58383 [ACK] Seq=26 Ack=13913 Win=1360640 Len=0
IN  TCP [TCP segment of a reassembled PDU]
IN  HTTP/XML    HTTP/1.1 400 Bad Request 
//the one above includes the error info quoted in the beginning
IN  TCP http > 58383 [FIN, ACK] Seq=649 Ack=13913 Win=1360640 Len=0
OUT TCP 58383 > http [ACK] Seq=13913 Ack=650 Win=65052 Len=0
OUT TCP 58383 > http [FIN, ACK] Seq=13913 Ack=650 Win=65052 Len=0
IN  TCP http > 58383 [ACK] Seq=650 Ack=13914 Win=1360640 Len=0

the only difference between above report and one generated by web-app based upload is that web-app based has less [TCP segment of a reassembled PDU] positions, and has some [TCP Dup ACK 156#1] http > 58364 [ACK] Sq=1 Ack=7017 Win=11668 Len=0 entries (if might be helpful I can send full traces).

回答1:

I spent about three days straight trying to solve the same issue. Make absolutely sure you use consistent line endings for your POST body format. I forgot a single carriage return (\r) in a CRLF sequence and Amazon S3 gave me this error and similar ones.



回答2:

solved! the boundary was wrong - it is needed to add 2 dashes more for post data than the value in the header has. what was needed to do in above code was:

string boundary = "---------------------------317205771417341028";
request.ContentType = "multipart/form-data; boundary=" + boundary;

[...]

using (Stream s = request.GetRequestStream())
{
    boundary = "--" + boundary "\n";

[...] so easy... and yet so annoying...



回答3:

POST that to your own server not Amazon, and then check the POST - I will bet that your headers are not set correctly, meaning that because you are using multipart form-data, the POST can't be decoded.

You should use the official SDK anyway.

http://aws.amazon.com/sdkfornet/



标签： .net http post httpwebrequest amazon-s3
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