Move Infrastructure.Jwt into Features.Users (#287)

web/backend/Features/Features.Users/Services/JwtInfrastructure.cs

@@ -0,0 +1,84 @@
+using System.Security.Claims;
+using System.Text;
+using Domain.Exceptions;
+using Microsoft.IdentityModel.JsonWebTokens;
+using Microsoft.IdentityModel.Tokens;
+using JwtRegisteredClaimNames = System.IdentityModel.Tokens.Jwt.JwtRegisteredClaimNames;
+
+namespace Features.Users.Services;
+
+/// <summary>
+///     Generates and validates HMAC-SHA256 signed JWTs using <see cref="JsonWebTokenHandler" />.
+/// </summary>
+public class JwtInfrastructure : ITokenInfrastructure
+{
+    /// <inheritdoc />
+    /// <remarks>
+    ///     Sets registered claims <c>sub</c> (userId), <c>unique_name</c> (username), <c>iat</c> (current UTC time),
+    ///     <c>exp</c> (expiry), and <c>jti</c> (a newly generated GUID).
+    /// </remarks>
+    /// <param name="secret">The symmetric secret used to sign the token, encoded as UTF-8 bytes.</param>
+    public string GenerateJwt(Guid userId, string username, DateTime expiry, string secret)
+    {
+        JsonWebTokenHandler handler = new();
+        byte[] key = Encoding.UTF8.GetBytes(secret);
+        List<Claim> claims = new()
+        {
+            new Claim(JwtRegisteredClaimNames.Sub, userId.ToString()),
+            new Claim(JwtRegisteredClaimNames.UniqueName, username),
+            new Claim(
+                JwtRegisteredClaimNames.Iat,
+                DateTimeOffset.UtcNow.ToUnixTimeSeconds().ToString()
+            ),
+            new Claim(
+                JwtRegisteredClaimNames.Exp,
+                new DateTimeOffset(expiry).ToUnixTimeSeconds().ToString()
+            ),
+            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
+        };
+
+        SecurityTokenDescriptor tokenDescriptor = new()
+        {
+            Subject = new ClaimsIdentity(claims),
+            Expires = expiry,
+            SigningCredentials = new SigningCredentials(
+                new SymmetricSecurityKey(key),
+                SecurityAlgorithms.HmacSha256
+            ),
+        };
+
+        return handler.CreateToken(tokenDescriptor);
+    }
+
+    /// <inheritdoc />
+    /// <remarks>Issuer and audience validation are disabled; only the signature and lifetime are validated.</remarks>
+    /// <param name="secret">The symmetric secret used to verify the token's signature, encoded as UTF-8 bytes.</param>
+    /// <exception cref="UnauthorizedException">
+    ///     Thrown when the token is invalid, has no claims identity, is expired, or otherwise fails validation.
+    /// </exception>
+    public async Task<ClaimsPrincipal> ValidateJwtAsync(string token, string secret)
+    {
+        JsonWebTokenHandler handler = new();
+        byte[] keyBytes = Encoding.UTF8.GetBytes(secret);
+        TokenValidationParameters parameters = new()
+        {
+            ValidateIssuer = false,
+            ValidateAudience = false,
+            ValidateLifetime = true,
+            IssuerSigningKey = new SymmetricSecurityKey(keyBytes),
+        };
+
+        try
+        {
+            TokenValidationResult? result = await handler.ValidateTokenAsync(token, parameters);
+            if (!result.IsValid || result.ClaimsIdentity == null)
+                throw new UnauthorizedAccessException();
+
+            return new ClaimsPrincipal(result.ClaimsIdentity);
+        }
+        catch (Exception)
+        {
+            throw new UnauthorizedException("Invalid token");
+        }
+    }
+}