Add analytics_id config: inject Google Analytics into dashboard pages

Node owners can set analytics_id in YAML config to automatically inject
the GA4 gtag.js snippet into all HTML pages served by the dashboard.
No injection when unset (default).

Author: frstrtr

config/c2pool_mainnet.yaml

@@ -96,3 +96,4 @@ storage_save_interval: 300     # Periodic sharechain save interval (seconds)
 
 # ─── Web Dashboard ──────────────────────────────────────────────────────────
 dashboard_dir: "web-static"    # Static dashboard directory (relative or absolute)
+# analytics_id: "G-XXXXXXXXXX"  # Google Analytics measurement ID (optional)

config/c2pool_testnet.yaml

@@ -58,6 +58,7 @@ cors_origin: "*"               # Access-Control-Allow-Origin header
 
 # ─── Web Dashboard ──────────────────────────────────────────────────────────
 dashboard_dir: "web-static"    # Static dashboard directory (relative or absolute)
+# analytics_id: "G-XXXXXXXXXX"  # Google Analytics measurement ID (optional)
 
 # ─── DOGE Merged Mining ─────────────────────────────────────────────────────
 doge_testnet4alpha: true       # Use testnet4alpha chain params (not testnet3)

src/c2pool/c2pool_refactored.cpp

@@ -502,6 +502,9 @@ int main(int argc, char* argv[]) {
     // Dashboard directory (web-static/ by default, relative to CWD)
     std::string dashboard_dir = "web-static";
 
+    // Google Analytics measurement ID (e.g. G-XXXXXXXXXX)
+    std::string analytics_id;
+
     // Optional encrypted authority message_data blob for local V36 shares.
     std::string operator_message_blob_hex;
 
@@ -1087,6 +1090,8 @@ int main(int argc, char* argv[]) {
                 storage_save_interval = cfg["storage_save_interval"].as<int>();
             if (!cli_explicit.count("dashboard_dir") && cfg["dashboard_dir"])
                 dashboard_dir = cfg["dashboard_dir"].as<std::string>();
+            if (cfg["analytics_id"])
+                analytics_id = cfg["analytics_id"].as<std::string>();
             if (cfg["cache_max_shared_hashes"])
                 cache_max_shared_hashes = cfg["cache_max_shared_hashes"].as<int>();
             if (cfg["cache_max_known_txs"])
@@ -1518,6 +1523,8 @@ int main(int argc, char* argv[]) {
 
             // Dashboard serving directory and payout address for legacy API
             web_server.set_dashboard_dir(dashboard_dir);
+            if (!analytics_id.empty())
+                web_server.set_analytics_id(analytics_id);
             web_server.get_mining_interface()->set_payout_address(payout_address);
             LOG_INFO << "Stratum config: min_diff=" << stratum_config.min_difficulty
                      << " max_diff=" << stratum_config.max_difficulty

src/core/web_server.cpp

@@ -469,6 +469,25 @@ void HttpSession::process_request()
                         std::string contents((std::istreambuf_iterator<char>(file)),
                                              std::istreambuf_iterator<char>());
 
+                        // Inject analytics tag into HTML pages if configured
+                        const auto& analytics_id = mining_interface_->get_analytics_id();
+                        if (!analytics_id.empty() && (ext == ".html" || ext == ".htm")) {
+                            auto pos = contents.find("</head>");
+                            if (pos == std::string::npos) pos = contents.find("</HEAD>");
+                            if (pos != std::string::npos) {
+                                std::string tag =
+                                    "<!-- analytics -->\n"
+                                    "<script async src=\"https://www.googletagmanager.com/gtag/js?id=" + analytics_id + "\"></script>\n"
+                                    "<script>\n"
+                                    "window.dataLayer=window.dataLayer||[];\n"
+                                    "function gtag(){dataLayer.push(arguments);}\n"
+                                    "gtag('js',new Date());\n"
+                                    "gtag('config','" + analytics_id + "');\n"
+                                    "</script>\n";
+                                contents.insert(pos, tag);
+                            }
+                        }
+
                         response.set(http::field::content_type, mime);
                         response.set(http::field::cache_control, "public, max-age=3600");
                         response.body() = std::move(contents);
@@ -5796,6 +5815,13 @@ void WebServer::set_dashboard_dir(const std::string& dir)
         LOG_INFO << "Dashboard serving from: " << dir;
 }
 
+void WebServer::set_analytics_id(const std::string& id)
+{
+    mining_interface_->set_analytics_id(id);
+    if (!id.empty())
+        LOG_INFO << "Analytics tag enabled: " << id;
+}
+
 bool WebServer::start_solo()
 {
     solo_mode_ = true;

src/core/web_server.hpp

@@ -867,6 +867,10 @@ class MiningInterface : public jsonrpccxx::JsonRpc2Server
     void set_dashboard_dir(const std::string& dir) { m_dashboard_dir = dir; }
     const std::string& get_dashboard_dir() const { return m_dashboard_dir; }
 
+    // Google Analytics (or compatible) measurement ID injected into HTML pages
+    void set_analytics_id(const std::string& id) { m_analytics_id = id; }
+    const std::string& get_analytics_id() const { return m_analytics_id; }
+
     // Primary payout address (for legacy /payout_addr endpoint)
     void set_payout_address(const std::string& addr) { m_payout_address = addr; }
     const std::string& get_payout_address() const { return m_payout_address; }
@@ -896,6 +900,8 @@ class MiningInterface : public jsonrpccxx::JsonRpc2Server
 
     // Dashboard static file serving directory (empty = disabled)
     std::string m_dashboard_dir;
+    // Google Analytics measurement ID (e.g. "G-XXXXXXXXXX")
+    std::string m_analytics_id;
     // Primary payout address for legacy API
     std::string m_payout_address;
 
@@ -1038,6 +1044,7 @@ class WebServer
 
     // Dashboard directory for static file serving
     void set_dashboard_dir(const std::string& dir);
+    void set_analytics_id(const std::string& id);
 
     // Wire a live coin-daemon RPC connection for block template generation
     void set_coin_rpc(ltc::coin::NodeRPC* rpc, ltc::interfaces::Node* coin = nullptr);