Fix empty JSON/XML requests being rejected by endpoints which allow empty bodies

Bunkum.Core/Endpoints/Middlewares/MainMiddleware.cs

@@ -215,7 +215,8 @@ private Response GenerateResponseFromEndpoint(object? val, EndpointAttribute att
                     return new Response([], ContentType.Plaintext, HttpStatusCode.BadRequest);
                 }
 
-                if (!this.TryGetBodyParameter(attribute, paramType, body, out arg))
+                // Don't try to deserialize/inject empty bodies if the endpoint explicitly allows them.
+                if (context.HasBody && !this.TryGetBodyParameter(attribute, paramType, body, out arg))
                 {
                     return new Response([], ContentType.Plaintext, HttpStatusCode.BadRequest);
                 }

BunkumTests.HttpServer/Endpoints/BodyEndpoints.cs

@@ -29,12 +29,32 @@ public Serializable Json(RequestContext context, Serializable body)
         return body;
     }
 
+    [AllowEmptyBody]
+    [HttpEndpoint("/body/json/optional", HttpMethods.Post, ContentType.Json)]
+    public Serializable OptionalJson(RequestContext context, Serializable? body)
+    {
+        return body ?? new()
+        {
+            Field = "had no body",
+        };
+    }
+
     [HttpEndpoint("/body/xml", HttpMethods.Post, ContentType.Xml)]
     public Serializable Xml(RequestContext context, Serializable body)
     {
         return body;
     }
 
+    [AllowEmptyBody]
+    [HttpEndpoint("/body/xml/optional", HttpMethods.Post, ContentType.Xml)]
+    public Serializable OptionalXml(RequestContext context, Serializable? body)
+    {
+        return body ?? new()
+        {
+            Field = "had no body",
+        };
+    }
+
     [HttpEndpoint("/body/byteArray", HttpMethods.Post)]
     public string ByteArray(RequestContext context, byte[] body)
     {

BunkumTests.HttpServer/Tests/BodyTests.cs

@@ -32,4 +32,86 @@ public async Task ReturnsBadRequestOnNoData()
         HttpResponseMessage msg = await client.PostAsync("/body/string", null);
         Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.BadRequest));
     }
+
+    [Test]
+    public async Task RejectsEmptyJsonBodyIfRequired()
+    {
+        (BunkumServer server, HttpClient client) = this.Setup();
+        server.AddEndpointGroup<BodyEndpoints>();
+
+        // empty bodies are rejected
+        HttpResponseMessage msg = await client.PostAsync("/body/json", null);
+        Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.BadRequest));
+
+        // but valid bodies are accepted
+        string requestBody = "{\"Field\":\"has body\"}";
+        msg = await client.PostAsync("/body/json", new StringContent(requestBody));
+        Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.OK));
+
+        string text = await msg.Content.ReadAsStringAsync();
+        Assert.That(text, Is.EqualTo(requestBody));
+    }
+
+    [Test]
+    public async Task AcceptsEmptyJsonBodyIfOptional()
+    {
+        (BunkumServer server, HttpClient client) = this.Setup();
+        server.AddEndpointGroup<BodyEndpoints>();
+
+        // empty bodies are accepted
+        HttpResponseMessage msg = await client.PostAsync("/body/json/optional", null);
+        Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.OK));
+
+        string text = await msg.Content.ReadAsStringAsync();
+        Assert.That(text, Is.EqualTo("{\"Field\":\"had no body\"}"));
+
+        // and valid bodies are also accepted
+        string requestBody = "{\"Field\":\"has body\"}";
+        msg = await client.PostAsync("/body/json/optional", new StringContent(requestBody));
+        Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.OK));
+
+        text = await msg.Content.ReadAsStringAsync();
+        Assert.That(text, Is.EqualTo(requestBody));
+    }
+
+    [Test]
+    public async Task RejectsEmptyXmlBodyIfRequired()
+    {
+        (BunkumServer server, HttpClient client) = this.Setup();
+        server.AddEndpointGroup<BodyEndpoints>();
+
+        // empty bodies are rejected
+        HttpResponseMessage msg = await client.PostAsync("/body/xml", null);
+        Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.BadRequest));
+
+        // but valid bodies are accepted
+        string requestBody = "<Serializable><Field>has body</Field></Serializable>";
+        msg = await client.PostAsync("/body/xml", new StringContent(requestBody));
+        Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.OK));
+
+        string text = await msg.Content.ReadAsStringAsync();
+        Assert.That(text, Is.EqualTo(requestBody));
+    }
+
+    [Test]
+    public async Task AcceptsEmptyXmlBodyIfOptional()
+    {
+        (BunkumServer server, HttpClient client) = this.Setup();
+        server.AddEndpointGroup<BodyEndpoints>();
+
+        // empty bodies are accepted
+        HttpResponseMessage msg = await client.PostAsync("/body/xml/optional", null);
+        Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.OK));
+
+        string text = await msg.Content.ReadAsStringAsync();
+        Assert.That(text, Is.EqualTo("<Serializable><Field>had no body</Field></Serializable>"));
+
+        // and valid bodies are also accepted
+        string requestBody = "<Serializable><Field>has body</Field></Serializable>";
+        msg = await client.PostAsync("/body/xml/optional", new StringContent(requestBody));
+        Assert.That(msg.StatusCode, Is.EqualTo(HttpStatusCode.OK));
+
+        text = await msg.Content.ReadAsStringAsync();
+        Assert.That(text, Is.EqualTo(requestBody));
+    }
 }