/// <summary>
/// Asynchroniously invoke VK API method and get response as XML.
/// </summary>
/// <param name="xmlMethodName">API method name, '.xml' added automatically</param>
/// <param name="methodCallArguments">Arguments to call method. May be empty.</param>
/// <param name="sendToken">Send access_token, or not.</param>
/// <returns>Response, if no error.</returns>
/// <exception cref="VK9.VK.APIException">Server returned an error.</exception>
public async Task<XmlElement> AsyncXmlMethodCall(string xmlMethodName, NameValueCollection methodCallArguments, bool sendToken = true)
{
// Request rate limit
BeginAnotherRequest();
_pendingCaptcha:
if (pendingCaptchaKey != null)
{
if (pendingCaptchaKey.IsSolved)
{
// Append args with solved captcha key
methodCallArguments.Add("captcha_sid", pendingCaptchaKey.ID);
methodCallArguments.Add("captcha_key", pendingCaptchaKey.SolveKey);
}
// HACK! It seems that server does not like token sent with captcha key at one time
// But what about method call result without token?
sendToken = false;
pendingCaptchaKey = null;
}
// Https?
string url = string.Format("{0}://{1}",
HostSession.IsHttpsEnabled ? "https" : "http",
ServerHost);
// Do we need to add access_token to arguments?
if (sendToken)
methodCallArguments.Add("access_token", HostSession.Token.Value);
// Append url with query string
var query_s = ToQueryString(methodCallArguments, true);
url += string.Format("/method/{0}.xml{1}",
xmlMethodName, !string.IsNullOrEmpty(query_s) ? "?" + query_s : string.Empty);
// Do we need to sign the request?
if (!HostSession.IsHttpsEnabled)
{
// Build sign_hash argument
query_s = ToQueryString(methodCallArguments, false);
string sig_url_s = string.Format("/method/{0}.xml{1}{2}",
xmlMethodName,
!string.IsNullOrEmpty(query_s) ? "?" + query_s : string.Empty,
HostSession.Secret);
// Generate sign
byte[] sig = null;
using (var md5 = MD5.Create())
sig = md5.ComputeHash(Encoding.UTF8.GetBytes(sig_url_s));
// Append url with digest
url += "&sig=";
for (int i = 0; i < sig.Length; i++)
url += sig[i].ToString("x2");
}
// Do HTTP request
string response_xml = await AsyncHttpGetString(url);
// Parse XML data
var xml = new XmlDocument();
xml.LoadXml(response_xml);
// Parse error info, if there is an error
if (xml["error"] != null)
{
// Get error message
XmlElement e = xml["error"]["error_msg"];
string msg = e != null
? e.InnerText
: "Error description is unspecified.";
// Parse error code
e = xml["error"]["error_code"];
var code = e != null
? (VK.APIError)uint.Parse(e.InnerText)
: VK.APIError.UnspecifiedUnsupported;
// Captcha validation needed?
if (code == VK.APIError.CaptchaNeeded)
{
// Remove captcha key from previous validation attempt
methodCallArguments.Remove("captcha_sid");
methodCallArguments.Remove("captcha_key");
// Trigger captcha validation
var eventData = VKSession.TriggerCaptchaNeeded(HostSession, new Uri(xml["error"]["captcha_img"].InnerText), xml["error"]["captcha_sid"].InnerText);
// Send the request again with/out captcha validation
if (eventData.Retry || eventData.IsSolved)
{
pendingCaptchaKey = eventData;
goto _pendingCaptcha;
}
}
// Throw error
throw new VK.APIException(HostSession, xmlMethodName, msg, code, xml["error"]["request_params"], null);
}
else
{
// Done
return xml["response"];
}
}
/// <summary>
/// Allows you to set captcha solution for next API request (used for delayed captcha validation).
/// </summary>
/// <param name="captchaKey">Captcha key</param>
public void SetCaptchaKey(VK.CaptchaEventArgs captchaKey)
{
if (captchaKey != null && (!captchaKey.IsSolved || !captchaKey.IsValidCaptcha))
throw new ArgumentException("Specified captchaKey is not valid or not solved'.");
pendingCaptchaKey = captchaKey;
}
/// <summary>
/// Triggers CaptchaNeeded event.
/// </summary>
public static VK.CaptchaEventArgs TriggerCaptchaNeeded(VKSession self, Uri img, string sid)
{
var eventData = new VK.CaptchaEventArgs(img, sid);
if (self.CaptchaNeeded != null)
self.CaptchaNeeded(self, eventData);
return eventData;
}