Merge #16240: JSONRPCRequest-aware RPCHelpMan

b6fb617aaa rpc: switch to using RPCHelpMan.Check() (Karl-Johan Alm)
c7a9fc234f Make the RPCHelpMan aware of JSONRPCRequest and add Check() helper (Karl-Johan Alm)
5c5e32bbe3 rpc: migrate JSONRPCRequest functionality into request.cpp (Karl-Johan Alm)
0ab8ba1ac6 rpc: fix RPC help requirements for getblocktemplate (Karl-Johan Alm)

Pull request description:

  Every single RPC call has a helper-section at the start, which throws a help string if the user asks for help or if the user provided too few/many arguments.

  ```C++
  const RPCHelpMan help{...};
  if (request.fHelp || !help.IsValidNumArgs(request.params.size())) {
      throw std::runtime_error(help.ToString());
  }
  ```

  or (older version)

  ```C++
  if (request.fHelp || request.params.size() < min || request.params.size() > max)
      throw std::runtime_error(
          RPCHelpMan{...}.ToString()
      );
  ```

  It seems like an obvious improvement, and less copy-pasting, to make `RPCHelpMan` aware of `JSONRPCRequest`, and to let it handle the checks instead. Both of the above become

  ```C++
  RPCHelpMan{...}.Check(request);
  ```

  which means we save roughly 3 lines per RPC command, and the `RPCHelpMan` instance is never referenced afterwards, so the approach is a tiny fraction cleaner.

  This is a complete update, sans a few special case locations that had special rules. 623 lines turn into 284 (which includes the addition to `RPCHelpMan`).

ACKs for top commit:
  laanwj:
    code rview and lightly tested ACK b6fb617aaa
  MarcoFalke:
    ACK b6fb617aaa, looked at the diff, verified move-only where applicable

Tree-SHA512: eb73f47f812512905b852e313281d1c8df803db40a6188aa39d5a7586631664db6764491152a8a96769946c796dc56d38c6e3a66ddd06ba3fb9d20050e6274e1

src/rpc/server.cpp

@@ -178,8 +178,6 @@ UniValue stop(const JSONRPCRequest& jsonRequest)
 
 static UniValue uptime(const JSONRPCRequest& jsonRequest)
 {
-    if (jsonRequest.fHelp || jsonRequest.params.size() > 0)
-        throw std::runtime_error(
             RPCHelpMan{"uptime",
                 "\nReturns the total uptime of the server.\n",
                             {},
@@ -190,15 +188,13 @@ static UniValue uptime(const JSONRPCRequest& jsonRequest)
                     HelpExampleCli("uptime", "")
                 + HelpExampleRpc("uptime", "")
                 },
-            }.ToString());
+            }.Check(jsonRequest);
 
     return GetTime() - GetStartupTime();
 }
 
 static UniValue getrpcinfo(const JSONRPCRequest& request)
 {
-    if (request.fHelp || request.params.size() > 0) {
-        throw std::runtime_error(
             RPCHelpMan{"getrpcinfo",
                 "\nReturns details of the RPC server.\n",
                 {},
@@ -217,9 +213,7 @@ static UniValue getrpcinfo(const JSONRPCRequest& request)
                 RPCExamples{
                     HelpExampleCli("getrpcinfo", "")
                 + HelpExampleRpc("getrpcinfo", "")},
-            }.ToString()
-        );
-    }
+            }.Check(request);
 
     LOCK(g_rpc_server_info.mutex);
     UniValue active_commands(UniValue::VARR);
@@ -334,39 +328,6 @@ bool RPCIsInWarmup(std::string *outStatus)
     return fRPCInWarmup;
 }
 
-void JSONRPCRequest::parse(const UniValue& valRequest)
-{
-    // Parse request
-    if (!valRequest.isObject())
-        throw JSONRPCError(RPC_INVALID_REQUEST, "Invalid Request object");
-    const UniValue& request = valRequest.get_obj();
-
-    // Parse id now so errors from here on will have the id
-    id = find_value(request, "id");
-
-    // Parse method
-    UniValue valMethod = find_value(request, "method");
-    if (valMethod.isNull())
-        throw JSONRPCError(RPC_INVALID_REQUEST, "Missing method");
-    if (!valMethod.isStr())
-        throw JSONRPCError(RPC_INVALID_REQUEST, "Method must be a string");
-    strMethod = valMethod.get_str();
-    if (fLogIPs)
-        LogPrint(BCLog::RPC, "ThreadRPCServer method=%s user=%s peeraddr=%s\n", SanitizeString(strMethod),
-            this->authUser, this->peerAddr);
-    else
-        LogPrint(BCLog::RPC, "ThreadRPCServer method=%s user=%s\n", SanitizeString(strMethod), this->authUser);
-
-    // Parse params
-    UniValue valParams = find_value(request, "params");
-    if (valParams.isArray() || valParams.isObject())
-        params = valParams;
-    else if (valParams.isNull())
-        params = UniValue(UniValue::VARR);
-    else
-        throw JSONRPCError(RPC_INVALID_REQUEST, "Params must be an array or object");
-}
-
 bool IsDeprecatedRPCEnabled(const std::string& method)
 {
     const std::vector<std::string> enabled_methods = gArgs.GetArgs("-deprecatedrpc");