Merge pull request #2917 from Rob-NY/server_bind_address

JSON-RPC: Add option to specify bind address for server

docs/JSON-RPC.md

@@ -17,6 +17,9 @@ It can be generated like this:
 $ openssl rand -base64 10 > /file/with/a/secret.txt
 ```
 
+The JSON-RPC server defaults to listening on the local loopback network interface (127.0.0.1).  This can be optionally changed by using the `--jsonrpcbindip <ip address>` command line option. **IPv4 only. IPv6 support has not been tested.**
+
+
 ## Wire protocol
 
 The JSON-RPC server is based on the [JSON-RPC 2.0](https://www.jsonrpc.org/specification) protocol, using [streaming newline-delimited JSON over TCP](https://clue.engineering/2018/introducing-reactphp-ndjson) as the transport. There are three main types of messages being exchanged:

src/global.h

@@ -284,8 +284,8 @@ LED bar:      lbr
 // minimum length of JSON-RPC secret string (main.cpp)
 #define JSON_RPC_MINIMUM_SECRET_LENGTH 16
 
-// JSON-RPC listen address
-#define JSON_RPC_LISTEN_ADDRESS "127.0.0.1"
+// JSON-RPC listen address (Default)
+#define DEFAULT_JSON_RPC_LISTEN_ADDRESS "127.0.0.1"
 
 #define _MAXSHORT     32767
 #define _MINSHORT     ( -32768 )

src/main.cpp

@@ -99,6 +99,7 @@ int main ( int argc, char** argv )
     int          iNumServerChannels          = DEFAULT_USED_NUM_CHANNELS;
     quint16      iPortNumber                 = DEFAULT_PORT_NUMBER;
     int          iJsonRpcPortNumber          = INVALID_PORT;
+    QString      strJsonRpcBindIP            = DEFAULT_JSON_RPC_LISTEN_ADDRESS;
     quint16      iQosNumber                  = DEFAULT_QOS_NUMBER;
     ELicenceType eLicenceType                = LT_NO_LICENCE;
     QString      strMIDISetup                = "";
@@ -209,6 +210,15 @@ int main ( int argc, char** argv )
             continue;
         }
 
+        // JSON-RPC bind address ------------------------------------------------
+        if ( GetStringArgument ( argc, argv, i, "--jsonrpcbindip", "--jsonrpcbindip", strArgument ) )
+        {
+            strJsonRpcBindIP = QString ( strArgument );
+            qInfo() << qUtf8Printable ( QString ( "- JSON-RPC will bind to: %1 if enabled" ).arg ( strJsonRpcBindIP ) );
+            CommandLineOptions << "--jsonrpcbindip";
+            continue;
+        }
+
         // Quality of Service --------------------------------------------------
         if ( GetNumericArgument ( argc, argv, i, "-Q", "--qos", 0, 255, rDbleArgument ) )
         {
@@ -783,6 +793,31 @@ int main ( int argc, char** argv )
                 strServerBindIP = "";
             }
         }
+
+#ifndef NO_JSON_RPC
+        //
+        // strJsonRpcBind address defaults to loopback and should not be empty, but
+        // in the odd chance that an empty IP is passed, we'll check for it here.
+
+        if ( strJsonRpcBindIP.trimmed().isEmpty() )
+        {
+            qCritical() << qUtf8Printable ( QString ( "JSON-RPC is enabled but no bind address was provided, exiting." ) );
+            exit ( 1 );
+        }
+
+        // This means of testing the validity of IP addresses is far from perfect but
+        // we do it here as an upfront check.  The downstream network calls will error
+        // out on malformed addresses not caught here.
+        {
+            QHostAddress InetAddr;
+            if ( !InetAddr.setAddress ( strJsonRpcBindIP ) )
+            {
+                qCritical() << qUtf8Printable ( QString ( "The JSON-RPC address specified is not valid, exiting. " ) );
+                exit ( 1 );
+            }
+        }
+
+#endif
     }
 
     // Application/GUI setup ---------------------------------------------------
@@ -880,7 +915,7 @@ int main ( int argc, char** argv )
         qWarning() << "- JSON-RPC: This interface is experimental and is subject to breaking changes even on patch versions "
                       "(not subject to semantic versioning) during the initial phase.";
 
-        pRpcServer = new CRpcServer ( pApp, iJsonRpcPortNumber, strJsonRpcSecret );
+        pRpcServer = new CRpcServer ( pApp, strJsonRpcBindIP, iJsonRpcPortNumber, strJsonRpcSecret );
         if ( !pRpcServer->Start() )
         {
             qCritical() << qUtf8Printable ( QString ( "- JSON-RPC: Server failed to start. Exiting." ) );
@@ -1072,6 +1107,7 @@ QString UsageArguments ( char** argv )
            "      --jsonrpcsecretfile\n"
            "                        path to a single-line file which contains a freely\n"
            "                        chosen secret to authenticate JSON-RPC users.\n"
+           "      --jsonrpcbindip   optional network address to bind RPC server. Defaults to 127.0.0.1 (IPv4 only, IPv6 not tested).\n"
            "  -Q, --qos             set the QoS value. Default is 128. Disable with 0\n"
            "                        (see the Jamulus website to enable QoS on Windows)\n"
            "  -t, --notranslation   disable translation (use English language)\n"

src/rpcserver.cpp

@@ -26,8 +26,9 @@
 #include "global.h"
 #include "rpcserver.h"
 
-CRpcServer::CRpcServer ( QObject* parent, int iPort, QString strSecret ) :
+CRpcServer::CRpcServer ( QObject* parent, QString strBindIP, int iPort, QString strSecret ) :
     QObject ( parent ),
+    strBindIP ( strBindIP ),
     iPort ( iPort ),
     strSecret ( strSecret ),
     pTransportServer ( new QTcpServer ( this ) )
@@ -60,7 +61,7 @@ bool CRpcServer::Start()
     {
         return false;
     }
-    if ( pTransportServer->listen ( QHostAddress ( JSON_RPC_LISTEN_ADDRESS ), iPort ) )
+    if ( pTransportServer->listen ( QHostAddress ( strBindIP ), iPort ) )
     {
         qInfo() << qUtf8Printable ( QString ( "- JSON-RPC: Server started on %1:%2" )
                                         .arg ( pTransportServer->serverAddress().toString() )

src/rpcserver.h

@@ -44,7 +44,7 @@ class CRpcServer : public QObject
     Q_OBJECT
 
 public:
-    CRpcServer ( QObject* parent, int iPort, QString secret );
+    CRpcServer ( QObject* parent, QString strBindIP, int iPort, QString secret );
     virtual ~CRpcServer();
 
     bool Start();
@@ -64,6 +64,7 @@ class CRpcServer : public QObject
     static const int iErrUnauthenticated      = 401;
 
 private:
+    QString     strBindIP;
     int         iPort;
     QString     strSecret;
     QTcpServer* pTransportServer;

tools/generate_json_rpc_docs.py

@@ -204,6 +204,9 @@ def to_markdown(self):
 $ openssl rand -base64 10 > /file/with/a/secret.txt
 ```
 
+The JSON-RPC server defaults to listening on the local loopback network interface (127.0.0.1).  This can be optionally changed by using the `--jsonrpcbindip <ip address>` command line option. **IPv4 only. IPv6 support has not been tested.**
+
+
 ## Wire protocol
 
 The JSON-RPC server is based on the [JSON-RPC 2.0](https://www.jsonrpc.org/specification) protocol, using [streaming newline-delimited JSON over TCP](https://clue.engineering/2018/introducing-reactphp-ndjson) as the transport. There are three main types of messages being exchanged: