Fix smoke fork bomb (#7401)

Content.Server/Body/Systems/BloodstreamSystem.cs

@@ -1,13 +1,14 @@
 using System.Linq;
 using Content.Server.Body.Components;
 using Content.Server.Chemistry.EntitySystems;
+using Content.Server.Chemistry.ReactionEffects;
 using Content.Server.Fluids.EntitySystems;
 using Content.Server.HealthExaminable;
 using Content.Server.Popups;
 using Content.Shared.Chemistry.Components;
+using Content.Shared.Chemistry.Reaction;
 using Content.Shared.Damage;
 using Content.Shared.Damage.Prototypes;
-using Content.Shared.Examine;
 using Content.Shared.FixedPoint;
 using Content.Shared.MobState.Components;
 using Robust.Shared.Audio;
@@ -38,6 +39,34 @@ public sealed class BloodstreamSystem : EntitySystem
         SubscribeLocalEvent<BloodstreamComponent, DamageChangedEvent>(OnDamageChanged);
         SubscribeLocalEvent<BloodstreamComponent, HealthBeingExaminedEvent>(OnHealthBeingExamined);
         SubscribeLocalEvent<BloodstreamComponent, BeingGibbedEvent>(OnBeingGibbed);
+        SubscribeLocalEvent<BloodstreamComponent, ReactionAttemptEvent>(OnReactionAttempt);
+    }
+
+    private void OnReactionAttempt(EntityUid uid, BloodstreamComponent component, ReactionAttemptEvent args)
+    {
+        if (args.Solution.Name != BloodstreamComponent.DefaultBloodSolutionName
+            && args.Solution.Name != BloodstreamComponent.DefaultChemicalsSolutionName
+            && args.Solution.Name != BloodstreamComponent.DefaultBloodTemporarySolutionName)
+            return;
+
+        foreach (var effect in args.Reaction.Effects)
+        {
+            switch (effect)
+            {
+                case CreateEntityReactionEffect: // Prevent entities from spawning in the bloodstream
+                case AreaReactionEffect: // No spontaneous smoke or foam leaking out of blood vessels.
+                    args.Cancel();
+                    return;
+            }
+        }
+
+        // The area-reaction effect canceling is part of avoiding smoke-fork-bombs (create two smoke bombs, that when
+        // ingested by mobs create more smoke). This also used to act as a rapid chemical-purge, because all the
+        // reagents would get carried away by the smoke/foam. This does still work for the stomach (I guess people vomit
+        // up the smoke or spawned entities?).
+
+        // TODO apply organ damage instead of just blocking the reaction?
+        // Having cheese-clots form in your veins can't be good for you.
     }
 
     public override void Update(float frameTime)

Content.Server/Chemistry/EntitySystems/SolutionAreaEffectSystem.cs

@@ -1,5 +1,7 @@
 using System.Linq;
 using Content.Server.Chemistry.Components;
+using Content.Server.Chemistry.ReactionEffects;
+using Content.Shared.Chemistry.Reaction;
 using JetBrains.Annotations;
 using Robust.Shared.GameObjects;
 
@@ -8,6 +10,13 @@ namespace Content.Server.Chemistry.EntitySystems
     [UsedImplicitly]
     public sealed class SolutionAreaEffectSystem : EntitySystem
     {
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            SubscribeLocalEvent<SolutionAreaEffectComponent, ReactionAttemptEvent>(OnReactionAttempt);
+        }
+
         public override void Update(float frameTime)
         {
             foreach (var inception in EntityManager.EntityQuery<SolutionAreaEffectInceptionComponent>().ToArray())
@@ -15,5 +24,21 @@ namespace Content.Server.Chemistry.EntitySystems
                 inception.InceptionUpdate(frameTime);
             }
         }
+
+        private void OnReactionAttempt(EntityUid uid, SolutionAreaEffectComponent component, ReactionAttemptEvent args)
+        {
+            if (args.Solution.Name != SolutionAreaEffectComponent.SolutionName)
+                return;
+
+            // Prevent smoke/foam fork bombs (smoke creating more smoke).
+            foreach (var effect in args.Reaction.Effects)
+            {
+                if (effect is AreaReactionEffect)
+                {
+                    args.Cancel();
+                    return;
+                }
+            }
+        }
     }
 }

Content.Server/Chemistry/EntitySystems/SolutionContainerSystem.Capabilities.cs

@@ -131,7 +131,10 @@ public sealed partial class SolutionContainerSystem
     public static string ToPrettyString(Solution solution)
     {
         var sb = new StringBuilder();
-        sb.Append("[");
+        if (solution.Name == null)
+            sb.Append("[");
+        else
+            sb.Append($"{solution.Name}:[");
         var first = true;
         foreach (var (id, quantity) in solution.Contents)
         {

Content.Server/Chemistry/EntitySystems/SolutionContainerSystem.cs

@@ -41,9 +41,9 @@ public sealed partial class SolutionContainerSystem : EntitySystem
 
     private void InitSolution(EntityUid uid, SolutionContainerManagerComponent component, ComponentInit args)
     {
-        foreach (var keyValue in component.Solutions)
+        foreach (var (name, solutionHolder) in component.Solutions)
         {
-            var solutionHolder = keyValue.Value;
+            solutionHolder.Name = name;
             if (solutionHolder.MaxVolume == FixedPoint2.Zero)
             {
                 solutionHolder.MaxVolume = solutionHolder.TotalVolume > solutionHolder.InitialMaxVolume
@@ -283,7 +283,7 @@ public sealed partial class SolutionContainerSystem : EntitySystem
 
         if (!solutionsMgr.Solutions.ContainsKey(name))
         {
-            var newSolution = new Solution();
+            var newSolution = new Solution() { Name = name };
             solutionsMgr.Solutions.Add(name, newSolution);
         }
 

Content.Shared/Chemistry/Components/Solution.cs

@@ -44,6 +44,11 @@ namespace Content.Shared.Chemistry.Components
 
         public Color Color => GetColor();
 
+        /// <summary>
+        ///     The name of this solution, if it is contained in some <see cref="SolutionContainerManagerComponent"/>
+        /// </summary>
+        public string? Name;
+
         /// <summary>
         ///     Constructs an empty solution (ex. an empty beaker).
         /// </summary>

Content.Shared/Chemistry/Reaction/SharedChemicalReactionSystem.cs

@@ -107,7 +107,7 @@ namespace Content.Shared.Chemistry.Reaction
         /// <param name="reaction">The reaction to check.</param>
         /// <param name="lowestUnitReactions">How many times this reaction can occur.</param>
         /// <returns></returns>
-        private static bool CanReact(Solution solution, ReactionPrototype reaction, out FixedPoint2 lowestUnitReactions)
+        private bool CanReact(Solution solution, ReactionPrototype reaction, EntityUid owner, out FixedPoint2 lowestUnitReactions)
         {
             lowestUnitReactions = FixedPoint2.MaxValue;
             if (solution.Temperature < reaction.MinimumTemperature)
@@ -120,6 +120,14 @@ namespace Content.Shared.Chemistry.Reaction
                 return false;
             }
 
+            var attempt = new ReactionAttemptEvent(reaction, solution);
+            RaiseLocalEvent(owner, attempt, false);
+            if (attempt.Cancelled)
+            {
+                lowestUnitReactions = FixedPoint2.Zero;
+                return false;
+            }
+
             foreach (var reactantData in reaction.Reactants)
             {
                 var reactantName = reactantData.Key;
@@ -220,7 +228,7 @@ namespace Content.Shared.Chemistry.Reaction
             // attempt to perform any applicable reaction
             foreach (var reaction in reactions)
             {
-                if (!CanReact(solution, reaction, out var unitReactions))
+                if (!CanReact(solution, reaction, owner, out var unitReactions))
                 {
                     toRemove.Add(reaction);
                     continue;
@@ -288,4 +296,22 @@ namespace Content.Shared.Chemistry.Reaction
             Logger.Error($"{nameof(Solution)} {owner} could not finish reacting in under {MaxReactionIterations} loops.");
         }
     }
+
+    /// <summary>
+    ///     Raised directed at the owner of a solution to determine whether the reaction should be allowed to occur.
+    /// </summary>
+    /// <reamrks>
+    ///     Some solution containers (e.g., bloodstream, smoke, foam) use this to block certain reactions from occurring.
+    /// </reamrks>
+    public sealed class ReactionAttemptEvent : CancellableEntityEventArgs
+    {
+        public readonly ReactionPrototype Reaction;
+        public readonly Solution Solution;
+
+        public ReactionAttemptEvent(ReactionPrototype reaction, Solution solution)
+        {
+            Reaction = reaction;
+            Solution = solution;
+        }
+    }
 }