问题
How do I implement reCaptcha in ASP.NET MVC and C#?
回答1:
There are a few great examples:
- Using ReCaptcha with ASP.NET MVC by Derik Whittaker
- MVC reCaptcha - making reCaptcha more MVC'ish.
- ReCaptcha Webhelper in ASP.NET MVC 3
- ReCaptcha Control for ASP.NET MVC from Google Code.
This has also been covered before in this Stack Overflow question.
NuGet Google reCAPTCHA V2 for MVC 4 and 5
- NuGet Package
- Demo And Document
回答2:
I have added reCaptcha to a project I'm currently working on. I needed it to use the AJAX API as the reCaptcha element was loaded into the page dynamically. I couldn't find any existing controls and the API is simple so I created my own.
I'll post my code here in case anyone finds it useful.
1: Add the script tag to the master page headers
<script type="text/javascript" src="http://www.google.com/recaptcha/api/js/recaptcha_ajax.js"></script>
2: Add your keys to the web.config
<appSettings>
<add key="ReCaptcha.PrivateKey" value="[key here]" />
<add key="ReCaptcha.PublicKey" value="[key here]" />
</appSettings>
3: Create the Action Attribute and Html Helper extensions
namespace [Your chosen namespace].ReCaptcha
{
public enum Theme { Red, White, BlackGlass, Clean }
[Serializable]
public class InvalidKeyException : ApplicationException
{
public InvalidKeyException() { }
public InvalidKeyException(string message) : base(message) { }
public InvalidKeyException(string message, Exception inner) : base(message, inner) { }
}
public class ReCaptchaAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
var userIP = filterContext.RequestContext.HttpContext.Request.UserHostAddress;
var privateKey = ConfigurationManager.AppSettings.GetString("ReCaptcha.PrivateKey", "");
if (string.IsNullOrWhiteSpace(privateKey))
throw new InvalidKeyException("ReCaptcha.PrivateKey missing from appSettings");
var postData = string.Format("&privatekey={0}&remoteip={1}&challenge={2}&response={3}",
privateKey,
userIP,
filterContext.RequestContext.HttpContext.Request.Form["recaptcha_challenge_field"],
filterContext.RequestContext.HttpContext.Request.Form["recaptcha_response_field"]);
var postDataAsBytes = Encoding.UTF8.GetBytes(postData);
// Create web request
var request = WebRequest.Create("http://www.google.com/recaptcha/api/verify");
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = postDataAsBytes.Length;
var dataStream = request.GetRequestStream();
dataStream.Write(postDataAsBytes, 0, postDataAsBytes.Length);
dataStream.Close();
// Get the response.
var response = request.GetResponse();
using (dataStream = response.GetResponseStream())
{
using (var reader = new StreamReader(dataStream))
{
var responseFromServer = reader.ReadToEnd();
if (!responseFromServer.StartsWith("true"))
((Controller)filterContext.Controller).ModelState.AddModelError("ReCaptcha", "Captcha words typed incorrectly");
}
}
}
}
public static class HtmlHelperExtensions
{
public static MvcHtmlString GenerateCaptcha(this HtmlHelper helper, Theme theme, string callBack = null)
{
const string htmlInjectString = @"<div id=""recaptcha_div""></div>
<script type=""text/javascript"">
Recaptcha.create(""{0}"", ""recaptcha_div"", {{ theme: ""{1}"" {2}}});
</script>";
var publicKey = ConfigurationManager.AppSettings.GetString("ReCaptcha.PublicKey", "");
if (string.IsNullOrWhiteSpace(publicKey))
throw new InvalidKeyException("ReCaptcha.PublicKey missing from appSettings");
if (!string.IsNullOrWhiteSpace(callBack))
callBack = string.Concat(", callback: ", callBack);
var html = string.Format(htmlInjectString, publicKey, theme.ToString().ToLower(), callBack);
return MvcHtmlString.Create(html);
}
}
}
4: Add the captcha to your view
@using (Html.BeginForm("MyAction", "MyController"))
{
@Html.TextBox("EmailAddress", Model.EmailAddress)
@Html.GenerateCaptcha(Theme.White)
<input type="submit" value="Submit" />
}
5: Add the attribute to your action
[HttpPost]
[ReCaptcha]
public ActionResult MyAction(MyModel model)
{
if (!ModelState.IsValid) // Will have a Model Error "ReCaptcha" if the user input is incorrect
return Json(new { capthcaInvalid = true });
... other stuff ...
}
6: Note you will need to reload the captcha after each post even if it was valid and another part of the form was invalid. Use Recaptcha.reload();
回答3:
Simple and Complete Solution working for me. Supports ASP.NET MVC 4 and 5 (Supports ASP.NET 4.0, 4.5, and 4.5.1)
Step 1: Install NuGet Package by "Install-Package reCAPTCH.MVC"
Step 2: Add your Public and Private key to your web.config file in appsettings section
<appSettings>
<add key="ReCaptchaPrivateKey" value=" -- PRIVATE_KEY -- " />
<add key="ReCaptchaPublicKey" value=" -- PUBLIC KEY -- " />
</appSettings>
You can create an API key pair for your site at https://www.google.com/recaptcha/intro/index.html and click on Get reCAPTCHA at top of the page
Step 3: Modify your form to include reCaptcha
@using reCAPTCHA.MVC
@using (Html.BeginForm())
{
@Html.Recaptcha()
@Html.ValidationMessage("ReCaptcha")
<input type="submit" value="Register" />
}
Step 4: Implement the Controller Action that will handle the form submission and Captcha validation
[CaptchaValidator(
PrivateKey = "your private reCaptcha Google Key",
ErrorMessage = "Invalid input captcha.",
RequiredMessage = "The captcha field is required.")]
public ActionResult MyAction(myVM model)
{
if (ModelState.IsValid) //this will take care of captcha
{
}
}
OR
public ActionResult MyAction(myVM model, bool captchaValid)
{
if (captchaValid) //manually check for captchaValid
{
}
}
回答4:
An async version for MVC 5 (i.e. avoiding ActionFilterAttribute, which is not async until MVC 6) and reCAPTCHA 2
ExampleController.cs
public class HomeController : Controller
{
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<ActionResult> ContactSubmit(
[Bind(Include = "FromName, FromEmail, FromPhone, Message, ContactId")]
ContactViewModel model)
{
if (!await RecaptchaServices.Validate(Request))
{
ModelState.AddModelError(string.Empty, "You have not confirmed that you are not a robot");
}
if (ModelState.IsValid)
{
...
ExampleView.cshtml
@model MyMvcApp.Models.ContactViewModel
@*This is assuming the master layout places the styles section within the head tags*@
@section Styles {
@Styles.Render("~/Content/ContactPage.css")
<script src='https://www.google.com/recaptcha/api.js'></script>
}
@using (Html.BeginForm("ContactSubmit", "Home",FormMethod.Post, new { id = "contact-form" }))
{
@Html.AntiForgeryToken()
...
<div class="form-group">
@Html.LabelFor(m => m.Message)
@Html.TextAreaFor(m => m.Message, new { @class = "form-control", @cols = "40", @rows = "3" })
@Html.ValidationMessageFor(m => m.Message)
</div>
<div class="row">
<div class="g-recaptcha" data-sitekey='@System.Configuration.ConfigurationManager.AppSettings["RecaptchaClientKey"]'></div>
</div>
<div class="row">
<input type="submit" id="submit-button" class="btn btn-default" value="Send Your Message" />
</div>
}
RecaptchaServices.cs
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Web;
using System.Configuration;
using System.Net.Http;
using System.Net.Http.Headers;
using Newtonsoft.Json;
using System.Runtime.Serialization;
namespace MyMvcApp.Services
{
public class RecaptchaServices
{
//ActionFilterAttribute has no async for MVC 5 therefore not using as an actionfilter attribute - needs revisiting in MVC 6
internal static async Task<bool> Validate(HttpRequestBase request)
{
string recaptchaResponse = request.Form["g-recaptcha-response"];
if (string.IsNullOrEmpty(recaptchaResponse))
{
return false;
}
using (var client = new HttpClient { BaseAddress = new Uri("https://www.google.com") })
{
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var content = new FormUrlEncodedContent(new[]
{
new KeyValuePair<string, string>("secret", ConfigurationManager.AppSettings["RecaptchaSecret"]),
new KeyValuePair<string, string>("response", recaptchaResponse),
new KeyValuePair<string, string>("remoteip", request.UserHostAddress)
});
var result = await client.PostAsync("/recaptcha/api/siteverify", content);
result.EnsureSuccessStatusCode();
string jsonString = await result.Content.ReadAsStringAsync();
var response = JsonConvert.DeserializeObject<RecaptchaResponse>(jsonString);
return response.Success;
}
}
[DataContract]
internal class RecaptchaResponse
{
[DataMember(Name = "success")]
public bool Success { get; set; }
[DataMember(Name = "challenge_ts")]
public DateTime ChallengeTimeStamp { get; set; }
[DataMember(Name = "hostname")]
public string Hostname { get; set; }
[DataMember(Name = "error-codes")]
public IEnumerable<string> ErrorCodes { get; set; }
}
}
}
web.config
<configuration>
<appSettings>
<!--recaptcha-->
<add key="RecaptchaSecret" value="***secret key from https://developers.google.com/recaptcha***" />
<add key="RecaptchaClientKey" value="***client key from https://developers.google.com/recaptcha***" />
</appSettings>
</configuration>
回答5:
I've successfully implemented ReCaptcha in the following way.
note: this is in VB, but can easily be converted
1] First grab a copy of the reCaptcha library
2] Then build a custom ReCaptcha HTML Helper
''# fix SO code coloring issue.
<Extension()>
Public Function reCaptcha(ByVal htmlHelper As HtmlHelper) As MvcHtmlString
Dim captchaControl = New Recaptcha.RecaptchaControl With {.ID = "recaptcha",
.Theme = "clean",
.PublicKey = "XXXXXX",
.PrivateKey = "XXXXXX"}
Dim htmlWriter = New HtmlTextWriter(New IO.StringWriter)
captchaControl.RenderControl(htmlWriter)
Return MvcHtmlString.Create(htmlWriter.InnerWriter.ToString)
End Function
3] From here you need a re-usable server side validator
Public Class ValidateCaptchaAttribute : Inherits ActionFilterAttribute
Private Const CHALLENGE_FIELD_KEY As String = "recaptcha_challenge_field"
Private Const RESPONSE_FIELD_KEY As String = "recaptcha_response_field"
Public Overrides Sub OnActionExecuting(ByVal filterContext As ActionExecutingContext)
If IsNothing(filterContext.HttpContext.Request.Form(CHALLENGE_FIELD_KEY)) Then
''# this will push the result value into a parameter in our Action
filterContext.ActionParameters("CaptchaIsValid") = True
Return
End If
Dim captchaChallengeValue = filterContext.HttpContext.Request.Form(CHALLENGE_FIELD_KEY)
Dim captchaResponseValue = filterContext.HttpContext.Request.Form(RESPONSE_FIELD_KEY)
Dim captchaValidtor = New RecaptchaValidator() With {.PrivateKey = "xxxxx",
.RemoteIP = filterContext.HttpContext.Request.UserHostAddress,
.Challenge = captchaChallengeValue,
.Response = captchaResponseValue}
Dim recaptchaResponse = captchaValidtor.Validate()
''# this will push the result value into a parameter in our Action
filterContext.ActionParameters("CaptchaIsValid") = recaptchaResponse.IsValid
MyBase.OnActionExecuting(filterContext)
End Sub
above this line is reusable **ONE TIME** code
below this line is how easy it is to implement reCaptcha over and over
Now that you have your re-usable code... all you need to do is add the captcha to your View.
<%: Html.reCaptcha %>
And when you post the form to your controller...
''# Fix SO code coloring issues
<ValidateCaptcha()>
<AcceptVerbs(HttpVerbs.Post)>
Function Add(ByVal CaptchaIsValid As Boolean, ByVal [event] As Domain.Event) As ActionResult
If Not CaptchaIsValid Then ModelState.AddModelError("recaptcha", "*")
'#' Validate the ModelState and submit the data.
If ModelState.IsValid Then
''# Post the form
Else
''# Return View([event])
End If
End Function
回答6:
Step 1: Client site integration
Paste this snippet before the closing </head> tag on your HTML template:
<script src='https://www.google.com/recaptcha/api.js'></script>
Paste this snippet at the end of the <form> where you want the reCAPTCHA widget to appear:
<div class="g-recaptcha" data-sitekey="your-site-key"></div>
Step 2: Server site integration
When your users submit the form where you integrated reCAPTCHA, you'll get as part of the payload a string with the name "g-recaptcha-response". In order to check whether Google has verified that user, send a POST request with these parameters:
URL : https://www.google.com/recaptcha/api/siteverify
secret : your secret key
response : The value of 'g-recaptcha-response'.
Now in action of your MVC app:
// return ActionResult if you want
public string RecaptchaWork()
{
// Get recaptcha value
var r = Request.Params["g-recaptcha-response"];
// ... validate null or empty value if you want
// then
// make a request to recaptcha api
using (var wc = new WebClient())
{
var validateString = string.Format(
"https://www.google.com/recaptcha/api/siteverify?secret={0}&response={1}",
"your_secret_key", // secret recaptcha key
r); // recaptcha value
// Get result of recaptcha
var recaptcha_result = wc.DownloadString(validateString);
// Just check if request make by user or bot
if (recaptcha_result.ToLower().Contains("false"))
{
return "recaptcha false";
}
}
// Do your work if request send from human :)
}
回答7:
For anybody else looking, here is a decent set of steps. http://forums.asp.net/t/1678976.aspx/1
Don't forget to manually add your key in OnActionExecuting() like I did.
回答8:
Extending Magpie's answer, here is the code for action filter which I use in my project.
It works with ASP Core RC2!
public class ReCaptchaAttribute : ActionFilterAttribute
{
private readonly string CAPTCHA_URL = "https://www.google.com/recaptcha/api/siteverify";
private readonly string SECRET = "your_secret";
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
try
{
// Get recaptcha value
var captchaResponse = filterContext.HttpContext.Request.Form["g-recaptcha-response"];
using (var client = new HttpClient())
{
var values = new Dictionary<string, string>
{
{ "secret", SECRET },
{ "response", captchaResponse },
{ "remoteip", filterContext.HttpContext.Request.HttpContext.Connection.RemoteIpAddress.ToString() }
};
var content = new FormUrlEncodedContent(values);
var result = client.PostAsync(CAPTCHA_URL, content).Result;
if (result.IsSuccessStatusCode)
{
string responseString = result.Content.ReadAsStringAsync().Result;
var captchaResult = JsonConvert.DeserializeObject<CaptchaResponseViewModel>(responseString);
if (!captchaResult.Success)
{
((Controller)filterContext.Controller).ModelState.AddModelError("ReCaptcha", "Captcha not solved");
}
} else
{
((Controller)filterContext.Controller).ModelState.AddModelError("ReCaptcha", "Captcha error");
}
}
}
catch (System.Exception)
{
((Controller)filterContext.Controller).ModelState.AddModelError("ReCaptcha", "Unknown error");
}
}
}
And use it in your code like
[ReCaptcha]
public IActionResult Authenticate()
{
if (!ModelState.IsValid)
{
return View(
"Login",
new ReturnUrlViewModel
{
ReturnUrl = Request.Query["returnurl"],
IsError = true,
Error = "Wrong reCAPTCHA"
}
);
}
来源：https://stackoverflow.com/questions/4611122/how-to-implement-recaptcha-for-asp-net-mvc