Use different ID for docker services if indicated by lab user name

Author: JanWichelmann

src/Ctf4e.LabServer/Models/State/UserState.cs

@@ -14,6 +14,12 @@ public class UserState
     public int? GroupId { get; set; }
 
     public List<UserState> GroupMembers { get; set; }
+    
+    /// <summary>
+    /// User ID to use when communicating with container.
+    /// Usually matches the CTF user ID, but may be overridden when the CTF system specifies a custom user name of form 'userXX'.
+    /// </summary>
+    public int DockerUserId { get; set; }
 
     public string UserName { get; set; }
 

src/Ctf4e.LabServer/Models/State/UserStateFile.cs

@@ -9,6 +9,7 @@ public class UserStateFile
 {
     public int? GroupId { get; set; }
 
+    public int DockerUserId { get; set; }
     public string UserName { get; set; }
 
     public string Password { get; set; }

src/Ctf4e.LabServer/Services/DockerService.cs

@@ -12,8 +12,8 @@ namespace Ctf4e.LabServer.Services;
 
 public interface IDockerService
 {
-    Task InitUserAsync(int userId, string userName, string password, CancellationToken cancellationToken);
-    Task<(bool passed, string stderr)> GradeAsync(string containerName, string gradingScriptPath, int userId, int exerciseId, string input, CancellationToken cancellationToken);
+    Task InitUserAsync(int dockerUserId, string userName, string password, CancellationToken cancellationToken);
+    Task<(bool passed, string stderr)> GradeAsync(string containerName, string gradingScriptPath, int dockerUserId, int exerciseId, string input, CancellationToken cancellationToken);
 }
 
 public class DockerService : IDockerService, IDisposable
@@ -40,14 +40,14 @@ public DockerService(IOptions<LabOptions> options)
         }
     }
 
-    public async Task InitUserAsync(int userId, string userName, string password, CancellationToken cancellationToken)
+    public async Task InitUserAsync(int dockerUserId, string userName, string password, CancellationToken cancellationToken)
     {
         if(_dockerClient == null)
             throw new InvalidOperationException("Docker support is not initialized.");
 
         if(string.IsNullOrWhiteSpace(_options.Value.DockerContainerInitUserScriptPath))
             throw new NotSupportedException("User initialization script is not specified.");
-            
+        
         // Prepare command
         var execCreateResponse = await _dockerClient.Exec.ExecCreateContainerAsync(_options.Value.DockerContainerName, new ContainerExecCreateParameters
         {
@@ -58,7 +58,7 @@ public async Task InitUserAsync(int userId, string userName, string password, Ca
             Cmd = new List<string>
             {
                 _options.Value.DockerContainerInitUserScriptPath,
-                userId.ToString(),
+                dockerUserId.ToString(),
                 userName,
                 password
             },
@@ -70,7 +70,7 @@ public async Task InitUserAsync(int userId, string userName, string password, Ca
         await execStream.ReadOutputToEndAsync(cancellationToken);
     }
 
-    public async Task<(bool passed, string stderr)> GradeAsync(string containerName, string gradingScriptPath, int userId, int exerciseId, string input, CancellationToken cancellationToken)
+    public async Task<(bool passed, string stderr)> GradeAsync(string containerName, string gradingScriptPath, int dockerUserId, int exerciseId, string input, CancellationToken cancellationToken)
     {
         if(_dockerClient == null)
             throw new InvalidOperationException("Docker support is not initialized.");
@@ -93,7 +93,7 @@ public async Task InitUserAsync(int userId, string userName, string password, Ca
                 Cmd = new List<string>
                 {
                     gradingScriptPath,
-                    userId.ToString(),
+                    dockerUserId.ToString(),
                     exerciseId.ToString()
                 },
                 Detach = false

src/Ctf4e.LabServer/Services/StateService.cs

@@ -152,6 +152,7 @@ public async Task ReloadAsync(CancellationToken cancellationToken)
                 Lock = new SemaphoreSlim(1, 1),
                 GroupId = userStateFile.GroupId,
                 GroupMembers = [],
+                DockerUserId = userStateFile.DockerUserId,
                 UserName = userStateFile.UserName,
                 Password = userStateFile.Password,
                 Exercises = new ConcurrentDictionary<int, UserStateFileExerciseEntry>(userStateFile.Exercises.ToDictionary(e => e.ExerciseId)),
@@ -251,6 +252,7 @@ private async Task WriteUserStateFileAsync(int userId, CancellationToken cancell
         var userStateFile = new UserStateFile
         {
             GroupId = userState.GroupId,
+            DockerUserId = userState.DockerUserId,
             UserName = userState.UserName,
             Password = userState.Password,
             Exercises = userState.Exercises.Values.ToList()
@@ -289,14 +291,20 @@ public async Task ProcessLoginAsync(int userId, int? groupId, string labUserName
             }
             else
             {
+                // If the CTF system sends a lab user name and that matches 'userXX', use 'XX' as docker user ID
+                int dockerUserId = userId;
+                if(labUserName != null && labUserName.StartsWith("user") && int.TryParse(labUserName[4..], out int duid))
+                    dockerUserId = duid;
+
                 // Create new account
                 userState = new UserState
                 {
                     Lock = new SemaphoreSlim(1, 1),
                     GroupId = groupId,
                     GroupMembers = [], // Will be filled later
                     Exercises = new ConcurrentDictionary<int, UserStateFileExerciseEntry>(),
-                    UserName = labUserName ?? (_dockerSupportEnabled ? $"user{userId}" : null),
+                    DockerUserId = dockerUserId,
+                    UserName = labUserName ?? (_dockerSupportEnabled ? $"user{dockerUserId}" : null),
                     Password = labPassword ?? (_dockerSupportEnabled ? RandomStringGenerator.GetRandomString(10) : null),
                     Log = new UserStateLogContainer(Math.Max(1, _options.Value.UserStateLogSize))
                 };
@@ -323,7 +331,7 @@ public async Task ProcessLoginAsync(int userId, int? groupId, string labUserName
                 if(_dockerSupportEnabled
                    && !string.IsNullOrWhiteSpace(_options.Value.DockerContainerName)
                    && !string.IsNullOrWhiteSpace(_options.Value.DockerContainerInitUserScriptPath))
-                    await _dockerService.InitUserAsync(userId, userState.UserName, userState.Password, CancellationToken.None);
+                    await _dockerService.InitUserAsync(userState.DockerUserId, userState.UserName, userState.Password, CancellationToken.None);
 
                 // Store new user state
                 _userStates.TryAdd(userId, userState);
@@ -438,7 +446,7 @@ public async Task<bool> CheckInputAsync(int exerciseId, int userId, object input
                 var scriptExercise = exercise as LabConfigurationScriptExerciseEntry;
                 string containerName = scriptExercise.ContainerName ?? _options.Value.DockerContainerName;
                 string gradingScriptPath = scriptExercise.GradeScriptPath ?? _options.Value.DockerContainerGradeScriptPath;
-                (correct, string stderr) = await _dockerService.GradeAsync(containerName, gradingScriptPath, userId, exerciseId, input as string, cancellationToken);
+                (correct, string stderr) = await _dockerService.GradeAsync(containerName, gradingScriptPath, userState.DockerUserId, exerciseId, input as string, cancellationToken);
 
                 userState.Log.AddMessage("Script stderr output", stderr);
             }