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DefaultAntiforgery.cs
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DefaultAntiforgery.cs
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// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
namespace Microsoft.AspNetCore.Antiforgery.Internal
{
/// <summary>
/// Provides access to the antiforgery system, which provides protection against
/// Cross-site Request Forgery (XSRF, also called CSRF) attacks.
/// </summary>
public class DefaultAntiforgery : IAntiforgery
{
private readonly AntiforgeryOptions _options;
private readonly IAntiforgeryTokenGenerator _tokenGenerator;
private readonly IAntiforgeryTokenSerializer _tokenSerializer;
private readonly IAntiforgeryTokenStore _tokenStore;
private readonly ILogger<DefaultAntiforgery> _logger;
public DefaultAntiforgery(
IOptions<AntiforgeryOptions> antiforgeryOptionsAccessor,
IAntiforgeryTokenGenerator tokenGenerator,
IAntiforgeryTokenSerializer tokenSerializer,
IAntiforgeryTokenStore tokenStore,
ILoggerFactory loggerFactory)
{
_options = antiforgeryOptionsAccessor.Value;
_tokenGenerator = tokenGenerator;
_tokenSerializer = tokenSerializer;
_tokenStore = tokenStore;
_logger = loggerFactory.CreateLogger<DefaultAntiforgery>();
}
/// <inheritdoc />
public AntiforgeryTokenSet GetAndStoreTokens(HttpContext httpContext)
{
if (httpContext == null)
{
throw new ArgumentNullException(nameof(httpContext));
}
CheckSSLConfig(httpContext);
var antiforgeryFeature = GetTokensInternal(httpContext);
var tokenSet = Serialize(antiforgeryFeature);
if (!antiforgeryFeature.HaveStoredNewCookieToken)
{
if (antiforgeryFeature.NewCookieToken != null)
{
// Serialize handles the new cookie token string.
Debug.Assert(antiforgeryFeature.NewCookieTokenString != null);
SaveCookieTokenAndHeader(httpContext, antiforgeryFeature.NewCookieTokenString);
antiforgeryFeature.HaveStoredNewCookieToken = true;
_logger.NewCookieToken();
}
else
{
_logger.ReusedCookieToken();
}
}
return tokenSet;
}
/// <inheritdoc />
public AntiforgeryTokenSet GetTokens(HttpContext httpContext)
{
if (httpContext == null)
{
throw new ArgumentNullException(nameof(httpContext));
}
CheckSSLConfig(httpContext);
var antiforgeryFeature = GetTokensInternal(httpContext);
return Serialize(antiforgeryFeature);
}
/// <inheritdoc />
public async Task<bool> IsRequestValidAsync(HttpContext httpContext)
{
if (httpContext == null)
{
throw new ArgumentNullException(nameof(httpContext));
}
CheckSSLConfig(httpContext);
var method = httpContext.Request.Method;
if (string.Equals(method, "GET", StringComparison.OrdinalIgnoreCase) ||
string.Equals(method, "HEAD", StringComparison.OrdinalIgnoreCase) ||
string.Equals(method, "OPTIONS", StringComparison.OrdinalIgnoreCase) ||
string.Equals(method, "TRACE", StringComparison.OrdinalIgnoreCase))
{
// Validation not needed for these request types.
return true;
}
var tokens = await _tokenStore.GetRequestTokensAsync(httpContext);
if (tokens.CookieToken == null)
{
_logger.MissingCookieToken(_options.CookieName);
return false;
}
if (tokens.RequestToken == null)
{
_logger.MissingRequestToken(_options.FormFieldName, _options.HeaderName);
return false;
}
// Extract cookie & request tokens
AntiforgeryToken deserializedCookieToken;
AntiforgeryToken deserializedRequestToken;
DeserializeTokens(httpContext, tokens, out deserializedCookieToken, out deserializedRequestToken);
// Validate
string message;
var result = _tokenGenerator.TryValidateTokenSet(
httpContext,
deserializedCookieToken,
deserializedRequestToken,
out message);
if (result)
{
_logger.ValidatedAntiforgeryToken();
}
else
{
_logger.ValidationFailed(message);
}
return result;
}
/// <inheritdoc />
public async Task ValidateRequestAsync(HttpContext httpContext)
{
if (httpContext == null)
{
throw new ArgumentNullException(nameof(httpContext));
}
CheckSSLConfig(httpContext);
var tokens = await _tokenStore.GetRequestTokensAsync(httpContext);
if (tokens.CookieToken == null)
{
throw new AntiforgeryValidationException(
Resources.FormatAntiforgery_CookieToken_MustBeProvided(_options.CookieName));
}
if (tokens.RequestToken == null)
{
if (_options.HeaderName == null)
{
var message = Resources.FormatAntiforgery_FormToken_MustBeProvided(_options.FormFieldName);
throw new AntiforgeryValidationException(message);
}
else if (!httpContext.Request.HasFormContentType)
{
var message = Resources.FormatAntiforgery_HeaderToken_MustBeProvided(_options.HeaderName);
throw new AntiforgeryValidationException(message);
}
else
{
var message = Resources.FormatAntiforgery_RequestToken_MustBeProvided(
_options.FormFieldName,
_options.HeaderName);
throw new AntiforgeryValidationException(message);
}
}
ValidateTokens(httpContext, tokens);
_logger.ValidatedAntiforgeryToken();
}
private void ValidateTokens(HttpContext httpContext, AntiforgeryTokenSet antiforgeryTokenSet)
{
Debug.Assert(!string.IsNullOrEmpty(antiforgeryTokenSet.CookieToken));
Debug.Assert(!string.IsNullOrEmpty(antiforgeryTokenSet.RequestToken));
// Extract cookie & request tokens
AntiforgeryToken deserializedCookieToken;
AntiforgeryToken deserializedRequestToken;
DeserializeTokens(
httpContext,
antiforgeryTokenSet,
out deserializedCookieToken,
out deserializedRequestToken);
// Validate
string message;
if (!_tokenGenerator.TryValidateTokenSet(
httpContext,
deserializedCookieToken,
deserializedRequestToken,
out message))
{
throw new AntiforgeryValidationException(message);
}
}
/// <inheritdoc />
public void SetCookieTokenAndHeader(HttpContext httpContext)
{
if (httpContext == null)
{
throw new ArgumentNullException(nameof(httpContext));
}
CheckSSLConfig(httpContext);
var antiforgeryFeature = GetCookieTokens(httpContext);
if (!antiforgeryFeature.HaveStoredNewCookieToken && antiforgeryFeature.NewCookieToken != null)
{
if (antiforgeryFeature.NewCookieTokenString == null)
{
antiforgeryFeature.NewCookieTokenString =
_tokenSerializer.Serialize(antiforgeryFeature.NewCookieToken);
}
SaveCookieTokenAndHeader(httpContext, antiforgeryFeature.NewCookieTokenString);
antiforgeryFeature.HaveStoredNewCookieToken = true;
_logger.NewCookieToken();
}
else
{
_logger.ReusedCookieToken();
}
}
private void SaveCookieTokenAndHeader(HttpContext httpContext, string cookieToken)
{
if (cookieToken != null)
{
// Persist the new cookie if it is not null.
_tokenStore.SaveCookieToken(httpContext, cookieToken);
}
if (!_options.SuppressXFrameOptionsHeader)
{
// Adding X-Frame-Options header to prevent ClickJacking. See
// http://tools.ietf.org/html/draft-ietf-websec-x-frame-options-10
// for more information.
httpContext.Response.Headers["X-Frame-Options"] = "SAMEORIGIN";
}
}
private void CheckSSLConfig(HttpContext context)
{
if (_options.RequireSsl && !context.Request.IsHttps)
{
throw new InvalidOperationException(Resources.FormatAntiforgeryWorker_RequireSSL(
nameof(AntiforgeryOptions),
nameof(AntiforgeryOptions.RequireSsl),
"true"));
}
}
private static IAntiforgeryFeature GetAntiforgeryFeature(HttpContext httpContext)
{
var antiforgeryFeature = httpContext.Features.Get<IAntiforgeryFeature>();
if (antiforgeryFeature == null)
{
antiforgeryFeature = new AntiforgeryFeature();
httpContext.Features.Set(antiforgeryFeature);
}
return antiforgeryFeature;
}
private IAntiforgeryFeature GetCookieTokens(HttpContext httpContext)
{
var antiforgeryFeature = GetAntiforgeryFeature(httpContext);
if (antiforgeryFeature.HaveGeneratedNewCookieToken)
{
Debug.Assert(antiforgeryFeature.HaveDeserializedCookieToken);
// Have executed this method earlier in the context of this request.
return antiforgeryFeature;
}
AntiforgeryToken cookieToken;
if (antiforgeryFeature.HaveDeserializedCookieToken)
{
cookieToken = antiforgeryFeature.CookieToken;
}
else
{
cookieToken = GetCookieTokenDoesNotThrow(httpContext);
antiforgeryFeature.CookieToken = cookieToken;
antiforgeryFeature.HaveDeserializedCookieToken = true;
}
AntiforgeryToken newCookieToken;
if (_tokenGenerator.IsCookieTokenValid(cookieToken))
{
// No need for the cookie token from the request after it has been verified.
newCookieToken = null;
}
else
{
// Need to make sure we're always operating with a good cookie token.
newCookieToken = _tokenGenerator.GenerateCookieToken();
Debug.Assert(_tokenGenerator.IsCookieTokenValid(newCookieToken));
}
antiforgeryFeature.HaveGeneratedNewCookieToken = true;
antiforgeryFeature.NewCookieToken = newCookieToken;
return antiforgeryFeature;
}
private AntiforgeryToken GetCookieTokenDoesNotThrow(HttpContext httpContext)
{
try
{
var serializedToken = _tokenStore.GetCookieToken(httpContext);
var token = _tokenSerializer.Deserialize(serializedToken);
return token;
}
catch
{
// ignore failures since we'll just generate a new token
return null;
}
}
private IAntiforgeryFeature GetTokensInternal(HttpContext httpContext)
{
var antiforgeryFeature = GetCookieTokens(httpContext);
if (antiforgeryFeature.NewRequestToken == null)
{
var cookieToken = antiforgeryFeature.NewCookieToken ?? antiforgeryFeature.CookieToken;
antiforgeryFeature.NewRequestToken = _tokenGenerator.GenerateRequestToken(
httpContext,
cookieToken);
}
return antiforgeryFeature;
}
private AntiforgeryTokenSet Serialize(IAntiforgeryFeature antiforgeryFeature)
{
// Should only be called after new tokens have been generated.
Debug.Assert(antiforgeryFeature.HaveGeneratedNewCookieToken);
Debug.Assert(antiforgeryFeature.NewRequestToken != null);
if (antiforgeryFeature.NewRequestTokenString == null)
{
antiforgeryFeature.NewRequestTokenString =
_tokenSerializer.Serialize(antiforgeryFeature.NewRequestToken);
}
if (antiforgeryFeature.NewCookieTokenString == null && antiforgeryFeature.NewCookieToken != null)
{
antiforgeryFeature.NewCookieTokenString =
_tokenSerializer.Serialize(antiforgeryFeature.NewCookieToken);
}
return new AntiforgeryTokenSet(
antiforgeryFeature.NewRequestTokenString,
antiforgeryFeature.NewCookieTokenString,
_options.FormFieldName,
_options.HeaderName);
}
private void DeserializeTokens(
HttpContext httpContext,
AntiforgeryTokenSet antiforgeryTokenSet,
out AntiforgeryToken cookieToken,
out AntiforgeryToken requestToken)
{
var antiforgeryFeature = GetAntiforgeryFeature(httpContext);
if (antiforgeryFeature.HaveDeserializedCookieToken)
{
cookieToken = antiforgeryFeature.CookieToken;
}
else
{
cookieToken = _tokenSerializer.Deserialize(antiforgeryTokenSet.CookieToken);
antiforgeryFeature.CookieToken = cookieToken;
antiforgeryFeature.HaveDeserializedCookieToken = true;
}
if (antiforgeryFeature.HaveDeserializedRequestToken)
{
requestToken = antiforgeryFeature.RequestToken;
}
else
{
requestToken = _tokenSerializer.Deserialize(antiforgeryTokenSet.RequestToken);
antiforgeryFeature.RequestToken = requestToken;
antiforgeryFeature.HaveDeserializedRequestToken = true;
}
}
}
}