From 2ca1460ae3a7217eaa8c5972515bf622bedadfce Mon Sep 17 00:00:00 2001
From: Matthew Zipkin <pinheadmz@gmail.com>
Date: Fri, 7 Jul 2023 14:31:18 -0400
Subject: [PATCH] rpc: identify JSON-RPC 2.0 requests

---
 src/rpc/request.cpp              | 19 +++++++++++++++++++
 src/rpc/request.h                |  6 ++++++
 test/functional/interface_rpc.py | 14 ++++++++------
 3 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/src/rpc/request.cpp b/src/rpc/request.cpp
index 12726ecc885..08e0658561b 100644
--- a/src/rpc/request.cpp
+++ b/src/rpc/request.cpp
@@ -167,6 +167,25 @@ void JSONRPCRequest::parse(const UniValue& valRequest)
     // Parse id now so errors from here on will have the id
     id = request.find_value("id");
 
+    // Check for JSON-RPC 2.0 (default 1.1)
+    m_json_version = JSONRPCVersion::V1_LEGACY;
+    const UniValue& jsonrpc_version = request.find_value("jsonrpc");
+    if (!jsonrpc_version.isNull()) {
+        if (!jsonrpc_version.isStr()) {
+            throw JSONRPCError(RPC_INVALID_REQUEST, "jsonrpc field must be a string");
+        }
+        // The "jsonrpc" key was added in the 2.0 spec, but some older documentation
+        // incorrectly included {"jsonrpc":"1.0"} in a request object, so we
+        // maintain that for backwards compatibility.
+        if (jsonrpc_version.get_str() == "1.0") {
+            m_json_version = JSONRPCVersion::V1_LEGACY;
+        } else if (jsonrpc_version.get_str() == "2.0") {
+            m_json_version = JSONRPCVersion::V2;
+        } else {
+            throw JSONRPCError(RPC_INVALID_REQUEST, "JSON-RPC version not supported");
+        }
+    }
+
     // Parse method
     const UniValue& valMethod{request.find_value("method")};
     if (valMethod.isNull())
diff --git a/src/rpc/request.h b/src/rpc/request.h
index 116ebb8aac1..8b721726953 100644
--- a/src/rpc/request.h
+++ b/src/rpc/request.h
@@ -11,6 +11,11 @@
 
 #include <univalue.h>
 
+enum class JSONRPCVersion {
+    V1_LEGACY,
+    V2
+};
+
 UniValue JSONRPCRequestObj(const std::string& strMethod, const UniValue& params, const UniValue& id);
 UniValue JSONRPCReplyObj(UniValue result, UniValue error, UniValue id);
 UniValue JSONRPCError(int code, const std::string& message);
@@ -35,6 +40,7 @@ public:
     std::string authUser;
     std::string peerAddr;
     std::any context;
+    JSONRPCVersion m_json_version = JSONRPCVersion::V1_LEGACY;
 
     void parse(const UniValue& valRequest);
 };
diff --git a/test/functional/interface_rpc.py b/test/functional/interface_rpc.py
index 748d83858ae..075dd1c2bcb 100755
--- a/test/functional/interface_rpc.py
+++ b/test/functional/interface_rpc.py
@@ -161,8 +161,10 @@ class RPCInterfaceTest(BitcoinTestFramework):
         self.log.info("Testing nonstandard jsonrpc 1.0 version number is accepted...")
         self.test_batch_request(lambda idx: BatchOptions(request_fields={"jsonrpc": "1.0"}))
 
-        self.log.info("Testing unrecognized jsonrpc version number is accepted...")
-        self.test_batch_request(lambda idx: BatchOptions(request_fields={"jsonrpc": "2.1"}))
+        self.log.info("Testing unrecognized jsonrpc version number is rejected...")
+        self.test_batch_request(lambda idx: BatchOptions(
+            request_fields={"jsonrpc": "2.1"},
+            response_fields={"result": None, "error": {"code": RPC_INVALID_REQUEST, "message": "JSON-RPC version not supported"}}))
 
     def test_http_status_codes(self):
         self.log.info("Testing HTTP status codes for JSON-RPC 1.1 requests...")
@@ -188,11 +190,11 @@ class RPCInterfaceTest(BitcoinTestFramework):
         expect_http_rpc_status(500, RPC_INVALID_PARAMETER,  self.nodes[0], "getblockhash", [42], 2, False)
         # force-send invalidly formatted requests
         response, status = send_json_rpc(self.nodes[0], {"jsonrpc": 2, "method": "getblockcount"})
-        assert_equal(response, {"error": None, "id": None, "result": 0})
-        assert_equal(status, 200)
+        assert_equal(response, {"id": None, "result": None, "error": {"code": RPC_INVALID_REQUEST, "message": "jsonrpc field must be a string"}})
+        assert_equal(status, 400)
         response, status = send_json_rpc(self.nodes[0], {"jsonrpc": "3.0", "method": "getblockcount"})
-        assert_equal(response, {"error": None, "id": None, "result": 0})
-        assert_equal(status, 200)
+        assert_equal(response, {"id": None, "result": None, "error": {"code": RPC_INVALID_REQUEST, "message": "JSON-RPC version not supported"}})
+        assert_equal(status, 400)
 
         self.log.info("Testing HTTP status codes for JSON-RPC 2.0 notifications...")
         # Not notification: id exists