Merge #18740: Remove g_rpc_node global

b3f7f375efb9a9ca9a7a4f2caf41fe3df2262520 refactor: Remove g_rpc_node global (Russell Yanofsky)
ccb5059ee89f6e8dc31ba5b82830b384890bb65e scripted-diff: Remove g_rpc_node references (Russell Yanofsky)
6fca33b2edc09ed62dab2323c780b31585de1750 refactor: Pass NodeContext to RPC and REST methods through util::Ref (Russell Yanofsky)
691c817b340d10e806dc3b1834d2a8fcc5e681fd Add util::Ref class as temporary alternative for c++17 std::any (Russell Yanofsky)

Pull request description:

  This PR removes the `g_rpc_node` global, to get same benefits we see removing other globals and make RPC code more testable, modular, and reusable.

  This uses a hybrid of the approaches suggested in #17548. Instead of using `std::any`, which isn't available in c++11, or `void*`, which isn't type safe, it uses a small new `util::Ref` helper class, which acts like a simplified `std::any` that only holds references, not values.

  Motivation for writing this was to provide an simpler alternative to #18647 by Harris Brakmić (brakmic) which avoids some shortcomings of that PR (https://github.com/bitcoin/bitcoin/pull/18647#issuecomment-617878826)

ACKs for top commit:
  MarcoFalke:
    re-ACK b3f7f375ef, only change is adding back const and more tests 🚾
  ajtowns:
    ACK b3f7f375efb9a9ca9a7a4f2caf41fe3df2262520

Tree-SHA512: 56292268a001bdbe34d641db1180c215351503966ff451e55cc96c9137f1d262225d7d7733de9c9da7ce7d7a4b34213a98c2476266b58c89dbbb0f3cb5aa5d70

1 files changed, 6 insertions, 5 deletions

diff --git a/src/httprpc.cpp b/src/httprpc.cpp
index 95e13998aa..f1b9997371 100644
--- a/src/httprpc.cpp
+++ b/src/httprpc.cpp
@@ -150,7 +150,7 @@ static bool RPCAuthorized(const std::string& strAuth, std::string& strAuthUserna
     return multiUserAuthorized(strUserPass);
 }
 
-static bool HTTPReq_JSONRPC(HTTPRequest* req, const std::string &)
+static bool HTTPReq_JSONRPC(const util::Ref& context, HTTPRequest* req)
 {
     // JSONRPC handles only POST
     if (req->GetRequestMethod() != HTTPRequest::POST) {
@@ -165,7 +165,7 @@ static bool HTTPReq_JSONRPC(HTTPRequest* req, const std::string &)
         return false;
     }
 
-    JSONRPCRequest jreq;
+    JSONRPCRequest jreq(context);
     jreq.peerAddr = req->GetPeer().ToString();
     if (!RPCAuthorized(authHeader.second, jreq.authUser)) {
         LogPrintf("ThreadRPCServer incorrect password attempt from %s\n", jreq.peerAddr);
@@ -284,15 +284,16 @@ static bool InitRPCAuthentication()
     return true;
 }
 
-bool StartHTTPRPC()
+bool StartHTTPRPC(const util::Ref& context)
 {
     LogPrint(BCLog::RPC, "Starting HTTP RPC server\n");
     if (!InitRPCAuthentication())
         return false;
 
-    RegisterHTTPHandler("/", true, HTTPReq_JSONRPC);
+    auto handle_rpc = [&context](HTTPRequest* req, const std::string&) { return HTTPReq_JSONRPC(context, req); };
+    RegisterHTTPHandler("/", true, handle_rpc);
     if (g_wallet_init_interface.HasWalletSupport()) {
-        RegisterHTTPHandler("/wallet/", false, HTTPReq_JSONRPC);
+        RegisterHTTPHandler("/wallet/", false, handle_rpc);
     }
     struct event_base* eventBase = EventBase();
     assert(eventBase);