Buscar HTML de Página

Utilizando o HttpWebRequest é possivel buscar o conteudo HTML de uma página.

Abaixo um exemplo:

public static String BuscarHtmlPagina(String url)
{
   ASCIIEncoding encoding = new ASCIIEncoding();
   String parametro = String.Empty;

   byte[] buffer = encoding.GetBytes(parametro);

   System.Uri enderecoRequisicaoTemplate = new Uri(url);

   HttpWebRequest requisicaoWeb = (HttpWebRequest)WebRequest.Create(enderecoRequisicaoTemplate);

   if (!String.IsNullOrEmpty(ConfigurationSettings.AppSettings["USUARIO-AUTENTICACAO"]))
   {
       requisicaoWeb.PreAuthenticate = true;

       CredentialCache credencial = new CredentialCache();
       credencial.Add(enderecoRequisicaoTemplate, "Basic", new NetworkCredential(ConfigurationSettings.AppSettings["USUARIO-AUTENTICACAO"], ConfigurationSettings.AppSettings["SENHA-AUTENTICACAO"], ConfigurationSettings.AppSettings["DOMINIO-AUTENTICACAO"]));
       requisicaoWeb.Credentials = credencial;
   }

   if (!String.IsNullOrEmpty(ConfigurationSettings.AppSettings["NOME-PROXY"]))
   {
       System.Net.WebProxy proxy = new System.Net.WebProxy(ConfigurationSettings.AppSettings["NOME-PROXY"], Convert.ToInt32(ConfigurationSettings.AppSettings["PORTA-PROXY"]));
       String usuarioProxy = ConfigurationSettings.AppSettings["USUARIO-PROXY"];
       String senhaProxy = ConfigurationSettings.AppSettings["SENHA-PROXY"];
       String dominioProxy = ConfigurationSettings.AppSettings["DOMINIO-PROXY"];

       proxy.Credentials = new System.Net.NetworkCredential(usuarioProxy, senhaProxy, dominioProxy);
       requisicaoWeb.Proxy = proxy;
   }

   requisicaoWeb.ContentType = "text/html; charset=windows-1252";
   requisicaoWeb.Timeout = 60000;
   requisicaoWeb.KeepAlive = true;
   requisicaoWeb.UserAgent = "Mozilla/4.0 (compatible;MSIE 6.0b;Windows NT 5.0)";
   requisicaoWeb.ContentLength = buffer.Length;
   requisicaoWeb.Method = "POST";
   requisicaoWeb.AllowAutoRedirect = true;
   requisicaoWeb.AllowWriteStreamBuffering = true;
   requisicaoWeb.MaximumAutomaticRedirections = 1;
   requisicaoWeb.Method = "POST";
   requisicaoWeb.ContentLength = buffer.Length;

   Stream stream = requisicaoWeb.GetRequestStream();
   stream.Write(buffer, 0, buffer.Length);
   stream.Close();
  
   HttpWebResponse httpWebResponse = null;
   Stream resposta = null;
   StreamReader streamRead = null;
   Char[] readBuffer = new Char[256];
  
   try
   {
       httpWebResponse = (HttpWebResponse)requisicaoWeb.GetResponse();
       resposta = httpWebResponse.GetResponseStream();
       Encoding enc = Encoding.GetEncoding(1252); 
       streamRead = new StreamReader(resposta, enc);

   }
   catch (Exception falha)
   {
       throw falha;
   }

   int contador = streamRead.Read(readBuffer, 0, 256);
   StringBuilder paginaRequisitada = new StringBuilder();

   while (contador > 0)
   {
       String resultData = new String(readBuffer, 0, contador);
       paginaRequisitada.Append(resultData);
       contador = streamRead.Read(readBuffer, 0, 256);
   }

   streamRead.Close();
   resposta.Close();

   httpWebResponse.Close();
   return paginaRequisitada.ToString();
}