From d0fb926f2adad8187503cf92b93ae694f8f7ec14 Mon Sep 17 00:00:00 2001
From: Jordan Bancino <jordan@bancino.net>
Date: Fri, 16 Sep 2022 11:27:34 -0400
Subject: [PATCH] Add error generation logic.

---
 site/index.html      |   6 +-
 src/Matrix.c         | 157 +++++++++++++++++++++++++++++++++++++++++++
 src/include/Matrix.h |  45 +++++++++++++
 3 files changed, 205 insertions(+), 3 deletions(-)

diff --git a/site/index.html b/site/index.html
index 790dd0b..fb1fb88 100644
--- a/site/index.html
+++ b/site/index.html
@@ -519,7 +519,7 @@ Design the server architecture
 <li>Route requests</li>
 <li><s>Handle requests</s></li>
 <li>Data abstraction layer</li>
-<li>Error generation</li>
+<li><s>Error generation</s></li>
 </ul>
 </li>
 </ul>
@@ -533,9 +533,9 @@ specification.
 <li>
 Client-Server API
 <ul>
-<li>Error responses</li>
+<li><s>Error responses</s></li>
 <li><code>/_matrix/client/versions</code></li>
-<li>CORS Headers</li>
+<li><s>CORS Headers</s></li>
 <li>Well-known URIs</li>
 <li>Client Authentication</li>
 <li>Capabilities negotiation</li>
diff --git a/src/Matrix.c b/src/Matrix.c
index 241d7b7..e841309 100644
--- a/src/Matrix.c
+++ b/src/Matrix.c
@@ -25,6 +25,8 @@
 #include <Matrix.h>
 
 #include <HttpServer.h>
+#include <Json.h>
+#include <Util.h>
 
 void
 MatrixHttpHandler(HttpServerContext * context, void *argp)
@@ -86,3 +88,158 @@ finish:
 
     LogConfigUnindent(lc);
 }
+
+HashMap *
+MatrixCreateError(MatrixError errorArg)
+{
+    HashMap *errorObj;
+    char *errcode;
+    char *error;
+
+    switch (errorArg)
+    {
+        case M_FORBIDDEN:
+            errcode = "M_FORBIDDEN";
+            error = "Forbidden access. Bad permissions or not authenticated.";
+            break;
+        case M_UNKNOWN_TOKEN:
+            errcode = "M_UNKNOWN_TOKEN";
+            error = "The access or refresh token specified was not recognized.";
+            break;
+        case M_MISSING_TOKEN:
+            errcode = "M_MISSING_TOKEN";
+            error = "No access token was specified for the request.";
+            break;
+        case M_BAD_JSON:
+            errcode = "M_BAD_JSON";
+            error = "Request contained valid JSON, but it was malformed in some way.";
+            break;
+        case M_NOT_JSON:
+            errcode = "M_NOT_JSON";
+            error = "Request did not contain valid JSON.";
+            break;
+        case M_NOT_FOUND:
+            errcode = "M_NOT_FOUND";
+            error = "No resource was found for this request.";
+            break;
+        case M_LIMIT_EXCEEDED:
+            errcode = "M_LIMIT_EXCEEDED";
+            error = "Too many requests have been sent in a short period of time. "
+                    "Wait a while then try again.";
+            break;
+        case M_UNKNOWN:
+            errcode = "M_UNKNOWN";
+            error = "An unknown error has occurred.";
+            break;
+
+        case M_UNRECOGNIZED:
+            errcode = "M_UNRECOGNIZED";
+            error = "The server did not understand the request.";
+            break;
+        case M_UNAUTHORIZED:
+            errcode = "M_UNAUTHORIZED";
+            error = "The request was not correctly authorized.";
+            break;
+        case M_USER_DEACTIVATED:
+            errcode = "M_USER_DEACTIVATED";
+            error = "The user ID assocated with the request has been deactivated.";
+            break;
+        case M_USER_IN_USE:
+            errcode = "M_USER_IN_USE";
+            error = "The user ID specified has already been taken.";
+            break;
+        case M_INVALID_USERNAME:
+            errcode = "M_INVALID_USERNAME";
+            error = "The user ID specified is not valid.";
+            break;
+        case M_ROOM_IN_USE:
+            errcode = "M_ROOM_IN_USE";
+            error = "The room alias given is already in use.";
+            break;
+        case M_INVALID_ROOM_STATE:
+            errcode = "M_INVALID_ROOM_STATE";
+            error = "The initial room state is invalid.";
+            break;
+        case M_THREEPID_IN_USE:
+            errcode = "M_THREEPID_IN_USE";
+            error = "The given threepid cannot be used because the same threepid is already in use.";
+            break;
+        case M_THREEPID_NOT_FOUND:
+            errcode = "M_THREEPID_NOT_FOUND";
+            error = "The given threepid cannot be used because no record matching the threepid "
+                    "was found.";
+            break;
+        case M_THREEPID_AUTH_FAILED:
+            errcode = "M_THREEPID_AUTH_FAILED";
+            error = "Authentication could not be performed on the third party identifier.";
+            break;
+        case M_THREEPID_DENIED:
+            errcode = "M_THREEPID_DENIED";
+            error = "The server does not permit this third party identifier.";
+            break;
+        case M_SERVER_NOT_TRUSTED:
+            errcode = "M_SERVER_NOT_TRUSTED";
+            error = "The request used a third party server that this server does not trust.";
+            break;
+        case M_UNSUPPORTED_ROOM_VERSION:
+            errcode = "M_UNSUPPORTED_ROOM_VERSION";
+            error = "The request to create a room used a room version that the server "
+                    "does not support.";
+            break;
+        case M_INCOMPATIBLE_ROOM_VERSION:
+            errcode = "M_INCOMPATIBLE_ROOM_VERSION";
+            error = "Attempted to join a room that has a version the server does not support.";
+            break;
+        case M_BAD_STATE:
+            errcode = "M_BAD_STATE";
+            error = "The state change requested cannot be performed.";
+            break;
+        case M_GUEST_ACCESS_FORBIDDEN:
+            errcode = "M_GUEST_ACCESS_FORBIDDEN";
+            error = "The room or resource does not permit guests to access it.";
+            break;
+        case M_CAPTCHA_NEEDED:
+            errcode = "M_CAPTCHA_NEEDED";
+            error = "A Captcha is required to complete the request.";
+            break;
+        case M_CAPTCHA_INVALID:
+            errcode = "M_CAPTCHA_INVALID";
+            error = "The Captcha provided did not match what was expected.";
+            break;
+        case M_MISSING_PARAM:
+            errcode = "M_MISSING_PARAM";
+            error = "A required parameter was missing from the request.";
+            break;
+        case M_TOO_LARGE:
+            errcode = "M_TOO_LARGE";
+            error = "The request or entity was too large.";
+            break;
+        case M_EXCLUSIVE:
+            errcode = "M_EXCLUSIVE";
+            error = "The resource being requested is reserved by an application service, "
+                    "or the application service making the request has not created the resource.";
+            break;
+        case M_RESOURCE_LIMIT_EXCEEDED:
+            errcode = "M_RESOURCE_LIMIT_EXCEEDED";
+            error = "The request cannot be completed because the homeserver has reached "
+                    "a resource limit imposed on it.";
+            break;
+        case M_CANNOT_LEAVE_SERVER_NOTICE_ROOM:
+            errcode = "M_CANNOT_LEAVE_SERVER_NOTICE_ROOM";
+            error = "The user is unable to reject an invite to join the server notices room.";
+            break;
+        default:
+            return NULL;
+    }
+
+    errorObj = HashMapCreate();
+    if (!errorObj)
+    {
+        return NULL;
+    }
+
+    HashMapSet(errorObj, "errcode", JsonValueString(UtilStringDuplicate(errcode)));
+    HashMapSet(errorObj, "error", JsonValueString(UtilStringDuplicate(error)));
+
+    return errorObj;
+}
diff --git a/src/include/Matrix.h b/src/include/Matrix.h
index f7a029a..c257b7d 100644
--- a/src/include/Matrix.h
+++ b/src/include/Matrix.h
@@ -26,6 +26,48 @@
 
 #include <HttpServer.h>
 #include <Log.h>
+#include <HashMap.h>
+
+typedef enum MatrixError
+{
+    M_FORBIDDEN,
+    M_UNKNOWN_TOKEN,
+    M_MISSING_TOKEN,
+    M_BAD_JSON,
+    M_NOT_JSON,
+    M_NOT_FOUND,
+    M_LIMIT_EXCEEDED,
+    M_UNKNOWN,
+
+    M_UNRECOGNIZED,
+    M_UNAUTHORIZED,
+    M_USER_DEACTIVATED,
+    M_USER_IN_USE,
+    M_INVALID_USERNAME,
+    M_ROOM_IN_USE,
+    M_INVALID_ROOM_STATE,
+
+    M_THREEPID_IN_USE,
+    M_THREEPID_NOT_FOUND,
+    M_THREEPID_AUTH_FAILED,
+    M_THREEPID_DENIED,
+
+    M_SERVER_NOT_TRUSTED,
+    M_UNSUPPORTED_ROOM_VERSION,
+    M_INCOMPATIBLE_ROOM_VERSION,
+    M_BAD_STATE,
+    M_GUEST_ACCESS_FORBIDDEN,
+    M_CAPTCHA_NEEDED,
+    M_CAPTCHA_INVALID,
+
+    M_MISSING_PARAM,
+    M_INVALID_PARAM,
+
+    M_TOO_LARGE,
+    M_EXCLUSIVE,
+    M_RESOURCE_LIMIT_EXCEEDED,
+    M_CANNOT_LEAVE_SERVER_NOTICE_ROOM
+} MatrixError;
 
 typedef struct MatrixHttpHandlerArgs
 {
@@ -35,4 +77,7 @@ typedef struct MatrixHttpHandlerArgs
 extern void
  MatrixHttpHandler(HttpServerContext *, void *);
 
+extern HashMap *
+ MatrixCreateError(MatrixError);
+
 #endif