/// <summary>
/// Creates a string that includes the information from the request in a
/// standardized (canonical) format.
/// </summary>
/// <param name="uri"></param>
/// <param name="httpMethodName"></param>
/// <param name="parameters"></param>
/// <param name="preSignedHeaders"></param>
/// <param name="requestPayload"></param>
/// <returns>canonical request string</returns>
/// <seealso cref="http://amazonpaycheckoutintegrationguide.s3.amazonaws.com/amazon-pay-api-v2/signing-requests.html"/>
public string CreateCanonicalRequest(ApiRequest apiRequest, Dictionary <String, List <String> > preSignedHeaders)
{
string path = apiRequest.Path.AbsolutePath;
StringBuilder canonicalRequestBuilder = new StringBuilder();
// if a body was passed to the request, convert it into a JSON string
string body = string.Empty;
if (apiRequest.Body != null)
{
body = apiRequest.BodyAsJsonString;
}
canonicalRequestBuilder.Append(apiRequest.HttpMethod.ToString())
.Append(LineSeparator)
.Append(canonicalBuilder.GetCanonicalizedURI(path))
.Append(LineSeparator)
.Append(canonicalBuilder.GetCanonicalizedQueryString(apiRequest.QueryParameters))
.Append(LineSeparator)
.Append(canonicalBuilder.GetCanonicalizedHeaderString(preSignedHeaders))
.Append(LineSeparator)
.Append(canonicalBuilder.GetSignedHeadersString(preSignedHeaders))
.Append(LineSeparator)
.Append(canonicalBuilder.HashThenHexEncode(body));
return(canonicalRequestBuilder.ToString());
}
/// <summary>
/// Helper method to execute the request
/// </summary>
protected virtual HttpWebResponse SendRequest(ApiRequest apiRequest, Dictionary <string, string> postSignedHeaders)
{
string path = apiRequest.Path.ToString();
// add the query parameters to the URL, if there are any
if (apiRequest.QueryParameters != null && apiRequest.QueryParameters.Count > 0)
{
var canonicalBuilder = new CanonicalBuilder();
path += "?" + canonicalBuilder.GetCanonicalizedQueryString(apiRequest.QueryParameters);
}
// TODO: move setting of SecurityProtocol into constructor
// ensure the right minimum TLS version is being used
if (Util.IsObsoleteSecurityProtocol(ServicePointManager.SecurityProtocol))
{
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
}
// TODO: consider switching to HttpClient class for web requests
// create the web request
HttpWebRequest request = WebRequest.Create(path) as HttpWebRequest;
foreach (KeyValuePair <string, string> header in postSignedHeaders)
{
if (WebHeaderCollection.IsRestricted(header.Key))
{
switch (header.Key)
{
case "accept":
request.Accept = header.Value;
break;
case "content-type":
request.ContentType = header.Value;
break;
case "user-agent":
request.UserAgent = header.Value;
break;
default:
throw new AmazonPayClientException("unknown header" + " " + header.Key);
}
}
else
{
request.Headers.Add(header.Key, header.Value);
}
}
request.Method = apiRequest.HttpMethod.ToString();
if (apiRequest.HttpMethod != HttpMethod.GET)
{
using (var streamWriter = new StreamWriter(request.GetRequestStream()))
{
streamWriter.Write(apiRequest.Body.ToJson());
streamWriter.Flush();
}
}
HttpWebResponse httpResponse;
try
{
httpResponse = request.GetResponse() as HttpWebResponse;
}
catch (WebException we)
{
httpResponse = (HttpWebResponse)we.Response as HttpWebResponse;
if (httpResponse == null)
{
throw new AmazonPayClientException("Http Response is empty " + we);
}
}
return(httpResponse);
}
