Fix leak in RouteConfig, update documentation.

Closes #15.

docs/CHANGELOG.md

@@ -31,6 +31,8 @@ Matrix clients. (#35)
 
 - Implemented `/_telodendria/admin/v1/deactivate/[localpart]` for admins to be able to 
 deactivate users.
+- Added a **PUT** option to `/_telodendria/admin/v1/config` that gives the ability to change
+only a subset of the configuration.
 - Moved all administrator API endpoints to `/_telodendria/admin/v1`, because later revisions
 of the administrator API may break clients, so we want a way to give those breaking revisions
 new endpoints.

docs/user/admin/config.md

@@ -4,7 +4,7 @@ As mentioned in [Setup](../setup.md), Telodendria's configuration is
 intended to be managed via the configuration API. Consult the
 [Configuration](../config.md) document for a complete list of supported
 configuration options. This document simply describes the API used to
-update the configuration.
+update the configuration described in that document.
 
 ## API Endpoints
 
@@ -40,3 +40,23 @@ configuration with the new one.
 |-------|------|-------------|
 | `restart_required` | `Boolean` | Whether or not the process needs to be restarted to finish applying the configuration. If this is `true`, then the restart endpoint should be used at a convenient time to apply the configuration.
 
+### **PUT** `/_telodendria/admin/config`
+
+Update the currently installed configuration instead of completely replacing it. This endpoint
+validates the request body, merges it on top of the current configuration, validates the resulting
+configuration, then updates it in the database. This is useful when only one or two properties
+in the configuration needs to be changed.
+
+| Requires Token | Rate Limited |
+|----------------|--------------|
+| Yes            | Yes          |
+
+| Response Code | Description |
+|---------------|-------------|
+| 200           | The new configuration was successfully installed.|
+
+#### 200 Response Format
+
+| Field | Type | Description |
+|-------|------|-------------|
+| `restart_required` | `Boolean` | Whether or not the process needs to be restarted to finish applying the configuration. If this is `true`, then the restart endpoint should be used at a convenient time to apply the configuration.

src/Routes/RouteConfig.c

@@ -135,8 +135,6 @@ ROUTE_IMPL(RouteConfig, path, argp)
 
             newConf = ConfigParse(newJson);
 
-            /* TODO: Don't leak newJson. */
-
             if (!newConf)
             {
                 HttpResponseStatus(args->context, HTTP_INTERNAL_SERVER_ERROR);
@@ -169,10 +167,11 @@ ROUTE_IMPL(RouteConfig, path, argp)
 
             ConfigFree(newConf);
             JsonFree(request);
+            JsonFree(newJson);
             break;
         default:
             HttpResponseStatus(args->context, HTTP_BAD_REQUEST);
-            response = MatrixErrorCreate(M_UNRECOGNIZED, NULL);
+            response = MatrixErrorCreate(M_UNRECOGNIZED, "Unknown request method.");
             break;
     }