feat: add db-based user log-on, invalidate tokens made for old passwords

Controllers/AuthController.cs

@@ -1,7 +1,9 @@
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using QuotifyBE.Data;
+using QuotifyBE.Entities;
 using QuotifyBE.DTOs;
+using System.Threading.Tasks;
 
 namespace QuotifyBE.Controllers;
 
@@ -21,14 +23,29 @@ public class AuthController : ControllerBase
     }
 
     [HttpPost("login")]
-    public IActionResult Login([FromBody] UserLoginDTO user, GeneralUseHelpers guhf)
+    public async Task<IActionResult> Login([FromBody] UserLoginDTO formUser, GeneralUseHelpers guhf)
     {
-        if (user.Email == "admin" && user.Password == "password")
+        // Ensure the form is complete
+        if (formUser.Email == null || formUser.Password == null)
         {
-            var token = guhf.GenerateJwtToken(user.Email, _appsettings);
-            return Ok(new { token });
+            return BadRequest(new {status = "error", error_msg = "Form contains missing data"});
         }
-        return Unauthorized();
+
+        // Find the user with retrieved e-mail
+        User? user = await guhf.GetUserFromEmail(formUser.Email);
+        if (user == null)
+        {
+            return NotFound(new {status = "error", error_msg = "User not found"});
+        }
+
+        // Hash the password and compare with the user-provided one
+        string hashedFormPassword = guhf.HashWithSHA512(formUser.Password);
+        if (hashedFormPassword == user.PasswordHash)
+        {
+            // All set - generate the token and return it
+            var token = guhf.GenerateJwtToken(formUser.Email, formUser.Password);
+            return Ok(new { status = "ok", token });
+        } else return Unauthorized(new {status = "error", error_msg = "Unknown pair of email and password"});
     }
 
     [HttpGet("some_values")]

Controllers/GeneralUseHelperFunctions.cs

@@ -1,13 +1,38 @@
+using Microsoft.EntityFrameworkCore;
 using Microsoft.IdentityModel.Tokens;
+using QuotifyBE.Data;
+using QuotifyBE.Entities;
 using System.IdentityModel.Tokens.Jwt;
 using System.Security.Claims;
+using System.Security.Cryptography;
 using System.Text;
 
 namespace QuotifyBE.Controllers;
 
-public class GeneralUseHelpers
+public class GeneralUseHelpers(ApplicationDbContext db, IConfiguration appsettings)
 {
-    public string GenerateJwtToken(string username, IConfiguration appsettings)
+    private readonly ApplicationDbContext _db          = db;
+    private readonly IConfiguration       _appsettings = appsettings;
+
+    async public Task<User?> GetUserFromEmail(string email)
+    {
+        return await _db.Users.FirstOrDefaultAsync(e => e.Email == email);
+    }
+
+
+    public string HashWithSHA512(string s)
+    {
+        using (var sha512 = SHA512.Create())
+        {
+            byte[] bytes = Encoding.ASCII.GetBytes(s);
+            byte[] hash = sha512.ComputeHash(bytes);
+            string hashstring = BitConverter.ToString(hash).Replace("-", "").ToLower();
+
+            return hashstring;
+        }
+    }
+
+    public string GenerateJwtToken(string username, string passwordHash)
     {
         var claims = new[]
         {
@@ -16,16 +41,20 @@ public class GeneralUseHelpers
         };
 
         var key = new SymmetricSecurityKey(
-            Encoding.UTF8.GetBytes(appsettings["JwtSecret"]!)
-            // won't be null here - otherwise Program.cs wouldn't start
+            // https://stackoverflow.com/questions/21978658/invalidating-json-web-tokens#comment45057142_23089839
+            // passwordHash is important for invalidating tokens after a user changed their password
+            Encoding.UTF8.GetBytes(
+                // JwtSecret won't be null here - otherwise Program.cs wouldn't start
+                _appsettings["JwtSecret"]! + passwordHash
+            )
         );
         var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);
 
         var token = new JwtSecurityToken(
-            issuer: appsettings["DomainName"]!,
-            audience: appsettings["DomainName"]!,
+            issuer: _appsettings["DomainName"]!,
+            audience: _appsettings["DomainName"]!,
             claims: claims,
-            expires: DateTime.Now.AddDays(7),
+            expires: DateTime.Now.AddMinutes(5),
             signingCredentials: creds
         );