rpc: Implement JSON-RPC structures and creation functions

Using these should result in cleaner code when building JSON-RPC
requests throughout the codebase.

src/rpc/jsonrpc.rs

@@ -0,0 +1,80 @@
+use rand::Rng;
+use serde::{Deserialize, Serialize};
+use serde_json::{json, Value};
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct JsonRequest {
+    jsonrpc: Value,
+    method: Value,
+    //params: Vec<Value>,
+    params: Value,
+    id: Value,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct JsonErrorVal {
+    code: Value,
+    message: Value,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct JsonError {
+    jsonrpc: Value,
+    error: JsonErrorVal,
+    id: Value,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct JsonResponse {
+    jsonrpc: Value,
+    result: Value,
+    id: Value,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct JsonNotification {
+    jsonrpc: Value,
+    method: Value,
+    //params: Vec<Value>,
+    params: Value,
+}
+
+pub fn request(m: Value, p: Value) -> JsonRequest {
+    let mut rng = rand::thread_rng();
+
+    return JsonRequest {
+        jsonrpc: json!("2.0"),
+        method: m,
+        params: p,
+        id: json!(rng.gen::<u32>()),
+    };
+}
+
+pub fn response(r: Value, i: Value) -> JsonResponse {
+    return JsonResponse {
+        jsonrpc: json!("2.0"),
+        result: r,
+        id: i,
+    };
+}
+
+pub fn error(c: i64, m: String, i: Value) -> JsonError {
+    let ev = JsonErrorVal {
+        code: json!(c),
+        message: json!(m),
+    };
+
+    return JsonError {
+        jsonrpc: json!("2.0"),
+        error: ev,
+        id: i,
+    };
+}
+
+pub fn notification(m: Value, p: Value) -> JsonNotification {
+    return JsonNotification {
+        jsonrpc: json!("2.0"),
+        method: m,
+        params: p,
+    };
+}

src/rpc/mod.rs

@@ -1,4 +1,5 @@
 pub mod adapter;
+pub mod jsonrpc;
 pub mod jsonserver;
 pub mod test;