asp.net core使用identity+jwt保护你的webapi(三)——refresh token
前言
上一篇已经介绍了identity的注册,登录,获取jwt token,本篇来完成refresh token。
开始
开始之前先说明一下为什么需要refresh token。
虽然jwt token有很多优点,但是它的缺点也是非常明显。由于jwt无状态的特性,所以jwt一旦颁发,基本上就不可控了,在过期时间内一直有效。有些场景下我们是希望能控制token失效的,比如用户的重要数据被修改时(密码,角色,权限,等等),我们希望用户重新获取token,甚至重新登录。
那么refresh token就可以很好的弥补jwt的缺陷。虽然refresh token也无法直接控制jwt失效,但是在refresh token机制下,我们可以把token的有效期设置的短一些,比如30分钟,而refresh token的有效期可以很长;因为refresh token会持久化到数据库中,它是完全可控的。
很多人纠结的jwt滑动刷新,无感刷新,在refresh token机制下,都不是问题。
生成refresh_token
改造一下上一篇的代码,首先refresh token需要持久化到数据库中,定义实体:
public class RefreshToken
{
[Key]
public int Id { get; set; }
[Required]
[StringLength(128)]
public string JwtId { get; set; }
[Required]
[StringLength(256)]
public string Token { get; set; }
/// <summary>
/// 是否使用,一个RefreshToken只能使用一次
/// </summary>
[Required]
public bool Used { get; set; }
/// <summary>
/// 是否失效。修改用户重要信息时可将此字段更新为true,使用户重新登录
/// </summary>
[Required]
public bool Invalidated { get; set; }
[Required]
public DateTime CreationTime { get; set; }
[Required]
public DateTime ExpiryTime { get; set; }
[Required]
public int UserId { get; set; }
[Required]
[ForeignKey(nameof(UserId))]
public AppUser User { get; set; }
}
加入到DbContext:
public class AppDbContext : IdentityDbContext<AppUser, IdentityRole<int>, int>
{
public DbSet<RefreshToken> RefreshTokens { get; set; }
public AppDbContext(DbContextOptions<AppDbContext> options)
: base(options)
{
}
// 省略......
}
ef迁移:
dotnet ef migrations add AppDbContext_Added_RefreshToken
dotnet ef database update
登录注册返回token时,也要把RefreshToken和ExpiresIn有效时间一起返回:
public class TokenResult
{
public bool Success => Errors == null || !Errors.Any();
public IEnumerable<string> Errors { get; set; }
public string AccessToken { get; set; }
public string TokenType { get; set; }
public int ExpiresIn { get; set; } // add
public string RefreshToken { get; set; } // add
}
public class TokenResponse
{
[JsonPropertyName("access_token")]
public string AccessToken { get; set; }
[JsonPropertyName("token_type")]
public string TokenType { get; set; }
[JsonPropertyName("expires_in")]
public int ExpiresIn { get; set; } // add
[JsonPropertyName("refresh_token")]
public string RefreshToken { get; set; } // add
}
修改UserService创建token方法:
private async Task<TokenResult> GenerateJwtToken(AppUser user)
{
var key = Encoding.ASCII.GetBytes(_jwtSettings.SecurityKey);
var tokenDescriptor = new SecurityTokenDescriptor
{
Subject = new ClaimsIdentity(new[]
{
new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString("N")),
new Claim(JwtRegisteredClaimNames.Sub, user.Id.ToString())
}),
IssuedAt = DateTime.UtcNow,
NotBefore = DateTime.UtcNow,
Expires = DateTime.UtcNow.Add(_jwtSettings.ExpiresIn),
SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key),
SecurityAlgorithms.HmacSha256Signature)
};
var jwtTokenHandler = new JwtSecurityTokenHandler();
var securityToken = jwtTokenHandler.CreateToken(tokenDescriptor);
var token = jwtTokenHandler.WriteToken(securityToken);
var refreshToken = new RefreshToken()
{
JwtId = securityToken.Id,
UserId = user.Id,
CreationTime = DateTime.UtcNow,
ExpiryTime = DateTime.UtcNow.AddMonths(6),
Token = GenerateRandomNumber()
};
await _appDbContext.RefreshTokens.AddAsync(refreshToken);
await _appDbContext.SaveChangesAsync();
return new TokenResult()
{
AccessToken = token,
TokenType = "Bearer",
RefreshToken = refreshToken.Token,
ExpiresIn = (int)_jwtSettings.ExpiresIn.TotalSeconds,
};
}
private string GenerateRandomNumber(int len = 32)
{
var randomNumber = new byte[len];
using var rng = RandomNumberGenerator.Create();
rng.GetBytes(randomNumber);
return Convert.ToBase64String(randomNumber);
}
登录测试,已经返回了refresh_token:
使用refresh_token获取token
// RefreshToken 请求参数
public class RefreshTokenRequest
{
[JsonPropertyName("access_token")]
public string AccessToken { get; set; }
[JsonPropertyName("refresh_token")]
public string RefreshToken { get; set; }
}
public interface IUserService
{
// 省略......
Task<TokenResult> RefreshTokenAsync(string token, string refreshToken); // add
}
RefreshTokenAsync
实现:
public async Task<TokenResult> RefreshTokenAsync(string token, string refreshToken)
{
var claimsPrincipal = GetClaimsPrincipalByToken(token);
if (claimsPrincipal == null)
{
// 无效的token...
return new TokenResult()
{
Errors = new[] { "1: Invalid request!" },
};
}
var expiryDateUnix =
long.Parse(claimsPrincipal.Claims.Single(x => x.Type == JwtRegisteredClaimNames.Exp).Value);
var expiryDateTimeUtc = UnixTimeStampToDateTime(expiryDateUnix);
if (expiryDateTimeUtc > DateTime.UtcNow)
{
// token未过期...
return new TokenResult()
{
Errors = new[] { "2: Invalid request!" },
};
}
var jti = claimsPrincipal.Claims.Single(x => x.Type == JwtRegisteredClaimNames.Jti).Value;
var storedRefreshToken =
await _appDbContext.RefreshTokens.SingleOrDefaultAsync(x => x.Token == refreshToken);
if (storedRefreshToken == null)
{
// 无效的refresh_token...
return new TokenResult()
{
Errors = new[] { "3: Invalid request!" },
};
}
if (storedRefreshToken.ExpiryTime < DateTime.UtcNow)
{
// refresh_token已过期...
return new TokenResult()
{
Errors = new[] { "4: Invalid request!" },
};
}
if (storedRefreshToken.Invalidated)
{
// refresh_token已失效...
return new TokenResult()
{
Errors = new[] { "5: Invalid request!" },
};
}
if (storedRefreshToken.Used)
{
// refresh_token已使用...
return new TokenResult()
{
Errors = new[] { "6: Invalid request!" },
};
}
if (storedRefreshToken.JwtId != jti)
{
// refresh_token与此token不匹配...
return new TokenResult()
{
Errors = new[] { "7: Invalid request!" },
};
}
storedRefreshToken.Used = true;
//_userDbContext.RefreshTokens.Update(storedRefreshToken);
await _appDbContext.SaveChangesAsync();
var dbUser = await _userManager.FindByIdAsync(storedRefreshToken.UserId.ToString());
return await GenerateJwtToken(dbUser);
}
解析token,注意这里的tokenValidationParameters
,这个参数和Startup中设置的tokenValidationParameters
唯一的区别是ValidateLifetime = false
,不验证过期时间。
private ClaimsPrincipal GetClaimsPrincipalByToken(string token)
{
try
{
var tokenValidationParameters = new TokenValidationParameters
{
ValidateIssuer = false,
ValidateAudience = false,
ValidateIssuerSigningKey = true,
IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(_jwtSettings.SecurityKey)),
ClockSkew = TimeSpan.Zero,
ValidateLifetime = false // 不验证过期时间!!!
};
var jwtTokenHandler = new JwtSecurityTokenHandler();
var claimsPrincipal =
jwtTokenHandler.ValidateToken(token, tokenValidationParameters, out var validatedToken);
var validatedSecurityAlgorithm = validatedToken is JwtSecurityToken jwtSecurityToken
&& jwtSecurityToken.Header.Alg.Equals(SecurityAlgorithms.HmacSha256,
StringComparison.InvariantCultureIgnoreCase);
return validatedSecurityAlgorithm ? claimsPrincipal : null;
}
catch
{
return null;
}
}
最后是UserController:
[HttpPost("RefreshToken")]
public async Task<IActionResult> RefreshToken(RefreshTokenRequest request)
{
var result = await _userService.RefreshTokenAsync(request.AccessToken, request.RefreshToken);
if (!result.Success)
{
return Unauthorized(new FailedResponse()
{
Errors = result.Errors
});
}
return Ok(new TokenResponse
{
AccessToken = result.AccessToken,
TokenType = result.TokenType,
ExpiresIn = result.ExpiresIn,
RefreshToken = result.RefreshToken
});
}
测试token未过期时刷新token:
正常刷新token:
refresh_token使用一次后,不可以再次使用:
其他情况可以自行测试。。。
最后
总结一下,上面的代码看似很多,其实完成的功能非常简单;就是在用户获取token时,后台生成一个与之对应的refresh token一并返回,同时将refresh token保存到数据库中;refresh token的存在就是为了当token过期时,能免登录刷新一次token。(refresh token只能使用一次,用户重要数据比如密码修改时,可以将refresh token置为失效,使用户重新登录)。代码已上传至 [blogs/asp.net core identity + jwt/code at main · xiajingren/blogs (github.com)](https://github.com/xiajingren/blogs/tree/main/asp.net core identity %2B jwt/code)
参考:
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作者:xhznl
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