Let RPC handle responses too

docs/README.md

@@ -2979,6 +2979,10 @@ Parameters:
 - `handler` - the RPC function performing the action for this method
 - `handler_data` - Arbitrary function data
 
+<span class="badge bg-info">NOTE:</span>
+if `method_pattern` is an empty string, this handler will be called to process
+JSON-RPC responses. Handling responses might be necessary if the JSON requests
+are initiated by both sides.
 
 Usage example:
 

mongoose.c

@@ -3550,20 +3550,27 @@ void mg_rpc_del(struct mg_rpc **head, void (*fn)(struct mg_rpc_req *)) {
   }
 }
 
+static void mg_rpc_call(struct mg_rpc_req *r, struct mg_str method) {
+  struct mg_rpc *h = r->head == NULL ? NULL : *r->head;
+  while (h != NULL && !mg_match(method, h->method, NULL)) h = h->next;
+  if (h != NULL) {
+    r->rpc = h;
+    h->fn(r);
+  } else {
+    mg_rpc_err(r, -32601, "\"%.*s not found\"", (int) method.len, method.ptr);
+  }
+}
+
 void mg_rpc_process(struct mg_rpc_req *r) {
   int len, off = mg_json_get(r->frame, "$.method", &len);
   if (off > 0 && r->frame.ptr[off] == '"') {
-    struct mg_str m = mg_str_n(&r->frame.ptr[off + 1], (size_t) len - 2);
+    struct mg_str method = mg_str_n(&r->frame.ptr[off + 1], (size_t) len - 2);
-    struct mg_rpc *h = r->head == NULL ? NULL : *r->head;
+    mg_rpc_call(r, method);
-    while (h != NULL && !mg_match(m, h->method, NULL)) h = h->next;
+  } else if ((off = mg_json_get(r->frame, "$.result", &len)) > 0 ||
-    if (h != NULL) {
+             (off = mg_json_get(r->frame, "$.error", &len)) > 0) {
-      r->rpc = h;
+    mg_rpc_call(r, mg_str(""));  // JSON response! call "" method handler
-      h->fn(r);
-    } else {
-      mg_rpc_err(r, -32601, "\"%.*s not found\"", (int) m.len, m.ptr);
-    }
   } else {
-    mg_rpc_err(r, -32700, "%.*Q", (int) r->frame.len, r->frame.ptr);
+    mg_rpc_err(r, -32700, "%.*Q", (int) r->frame.len, r->frame.ptr);  // Invalid
   }
 }
 

src/rpc.c

@@ -20,20 +20,27 @@ void mg_rpc_del(struct mg_rpc **head, void (*fn)(struct mg_rpc_req *)) {
   }
 }
 
+static void mg_rpc_call(struct mg_rpc_req *r, struct mg_str method) {
+  struct mg_rpc *h = r->head == NULL ? NULL : *r->head;
+  while (h != NULL && !mg_match(method, h->method, NULL)) h = h->next;
+  if (h != NULL) {
+    r->rpc = h;
+    h->fn(r);
+  } else {
+    mg_rpc_err(r, -32601, "\"%.*s not found\"", (int) method.len, method.ptr);
+  }
+}
+
 void mg_rpc_process(struct mg_rpc_req *r) {
   int len, off = mg_json_get(r->frame, "$.method", &len);
   if (off > 0 && r->frame.ptr[off] == '"') {
-    struct mg_str m = mg_str_n(&r->frame.ptr[off + 1], (size_t) len - 2);
+    struct mg_str method = mg_str_n(&r->frame.ptr[off + 1], (size_t) len - 2);
-    struct mg_rpc *h = r->head == NULL ? NULL : *r->head;
+    mg_rpc_call(r, method);
-    while (h != NULL && !mg_match(m, h->method, NULL)) h = h->next;
+  } else if ((off = mg_json_get(r->frame, "$.result", &len)) > 0 ||
-    if (h != NULL) {
+             (off = mg_json_get(r->frame, "$.error", &len)) > 0) {
-      r->rpc = h;
+    mg_rpc_call(r, mg_str(""));  // JSON response! call "" method handler
-      h->fn(r);
-    } else {
-      mg_rpc_err(r, -32601, "\"%.*s not found\"", (int) m.len, m.ptr);
-    }
   } else {
-    mg_rpc_err(r, -32700, "%.*Q", (int) r->frame.len, r->frame.ptr);
+    mg_rpc_err(r, -32700, "%.*Q", (int) r->frame.len, r->frame.ptr);  // Invalid
   }
 }
 

test/unit_test.c

@@ -2493,6 +2493,11 @@ static void test_json(void) {
   }
 }
 
+static void resp_rpc(struct mg_rpc_req *r) {
+  int len = 0, off = mg_json_get(r->frame, "$.result", &len);
+  mg_xprintf(r->pfn, r->pfn_data, "%.*s", len, &r->frame.ptr[off]);
+}
+
 static void test_rpc(void) {
   struct mg_rpc *head = NULL;
   struct mg_iobuf io = {0, 0, 0, 256};
@@ -2541,10 +2546,30 @@ static void test_rpc(void) {
     const char *resp = "{\"error\":{\"code\":-32700,\"message\":\"haha\"}}";
     req.frame = mg_str("haha");
     mg_rpc_process(&req);
+    // MG_INFO(("-> %s", io.buf));
     ASSERT(strcmp((char *) io.buf, resp) == 0);
     mg_iobuf_free(&io);
   }
 
+  {
+    const char *resp =
+        "{\"id\":1,\"error\":{\"code\":-32601,\"message\":\" not found\"}}";
+    req.frame = mg_str("{\"id\":1,\"result\":123}");
+    mg_rpc_process(&req);
+    // MG_INFO(("-> %s", io.buf));
+    ASSERT(strcmp((char *) io.buf, resp) == 0);
+    mg_iobuf_free(&io);
+  }
+
+  {
+    req.frame = mg_str("{\"id\":1,\"result\":123}");
+    mg_rpc_add(&head, mg_str(""), resp_rpc, NULL);
+    mg_rpc_process(&req);
+    MG_INFO(("-> %s", io.buf));
+    ASSERT(strcmp((char *) io.buf, "123") == 0);
+    mg_iobuf_free(&io);
+  }
+
   mg_rpc_del(&head, NULL);
   ASSERT(head == NULL);
 }