rpc: Named argument support for bitcoin-cli

Usage e.g.:

    $ src/bitcoin-cli -testnet -named echo arg0="dfdf"
    [
    "dfdf"
    ]

Argument conversion also works, for arguments thus flagged in the table in
`src/rpc/client.cpp`.

    $ src/bitcoin-cli -testnet -named echojson arg0="[1,2,3]"
    [
      [
        1,
        2,
        3
      ]
    ]

Unknown parameter (detected server-side):

    $ src/bitcoin-cli -testnet -named getinfo arg0="dfdf"
    error code: -8
    error message:
    Unknown named parameter arg0

1 files changed, 11 insertions, 1 deletions

diff --git a/src/bitcoin-cli.cpp b/src/bitcoin-cli.cpp
index e9b530114c..1c330cf5ea 100644
--- a/src/bitcoin-cli.cpp
+++ b/src/bitcoin-cli.cpp
@@ -25,6 +25,7 @@
 
 static const char DEFAULT_RPCCONNECT[] = "127.0.0.1";
 static const int DEFAULT_HTTP_CLIENT_TIMEOUT=900;
+static const bool DEFAULT_NAMED=false;
 static const int CONTINUE_EXECUTION=-1;
 
 std::string HelpMessageCli()
@@ -35,6 +36,7 @@ std::string HelpMessageCli()
     strUsage += HelpMessageOpt("-conf=<file>", strprintf(_("Specify configuration file (default: %s)"), BITCOIN_CONF_FILENAME));
     strUsage += HelpMessageOpt("-datadir=<dir>", _("Specify data directory"));
     AppendParamsHelpMessages(strUsage);
+    strUsage += HelpMessageOpt("-named", strprintf(_("Pass named instead of positional arguments (default: %s)"), DEFAULT_NAMED));
     strUsage += HelpMessageOpt("-rpcconnect=<ip>", strprintf(_("Send commands to node running on <ip> (default: %s)"), DEFAULT_RPCCONNECT));
     strUsage += HelpMessageOpt("-rpcport=<port>", strprintf(_("Connect to JSON-RPC on <port> (default: %u or testnet: %u)"), BaseParams(CBaseChainParams::MAIN).RPCPort(), BaseParams(CBaseChainParams::TESTNET).RPCPort()));
     strUsage += HelpMessageOpt("-rpcwait", _("Wait for RPC server to start"));
@@ -80,6 +82,7 @@ static int AppInitRPC(int argc, char* argv[])
         if (!IsArgSet("-version")) {
             strUsage += "\n" + _("Usage:") + "\n" +
                   "  bitcoin-cli [options] <command> [params]  " + strprintf(_("Send command to %s"), _(PACKAGE_NAME)) + "\n" +
+                  "  bitcoin-cli [options] -named <command> [name=value] ... " + strprintf(_("Send command to %s (with named arguments)"), _(PACKAGE_NAME)) + "\n" +
                   "  bitcoin-cli [options] help                " + _("List commands") + "\n" +
                   "  bitcoin-cli [options] help <command>      " + _("Get help for a command") + "\n";
 
@@ -278,7 +281,14 @@ int CommandLineRPC(int argc, char *argv[])
         if (args.size() < 1)
             throw std::runtime_error("too few parameters (need at least command)");
         std::string strMethod = args[0];
-        UniValue params = RPCConvertValues(strMethod, std::vector<std::string>(args.begin()+1, args.end()));
+        args.erase(args.begin()); // Remove trailing method name from arguments vector
+
+        UniValue params;
+        if(GetBoolArg("-named", DEFAULT_NAMED)) {
+            params = RPCConvertNamedValues(strMethod, args);
+        } else {
+            params = RPCConvertValues(strMethod, args);
+        }
 
         // Execute and handle connection failures with -rpcwait
         const bool fWait = GetBoolArg("-rpcwait", false);