From 025f49a5fd667afb8d672d3639f8fc806d0a3928 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=92=D0=B0=D1=88=D0=B5=20=D0=98=D0=BC=D1=8F?=
 <you@example.com>
Date: Tue, 7 Oct 2025 18:40:54 +0400
Subject: [PATCH] feat(core): add LocalPingScanner for subnet host discovery

---
 src/core/local_ping_scanner.cpp | 103 ++++++++++++++++++++++++++++++++
 src/core/local_ping_scanner.hpp |  26 ++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 src/core/local_ping_scanner.cpp
 create mode 100644 src/core/local_ping_scanner.hpp

diff --git a/src/core/local_ping_scanner.cpp b/src/core/local_ping_scanner.cpp
new file mode 100644
index 0000000..d71a2bf
--- /dev/null
+++ b/src/core/local_ping_scanner.cpp
@@ -0,0 +1,103 @@
+#include "local_ping_scanner.hpp"
+#include "logger.hpp"
+#include <Poco/Net/ICMPClient.h>
+#include <boost/asio/ip/address_v4.hpp>
+#include <stdexcept>
+
+LocalPingScanner::LocalPingScanner(
+    const std::string &baseIp, int prefixLen, int timeoutMs
+)
+    : baseIp_(baseIp)
+    , prefixLen_(prefixLen)
+    , timeoutMs_(timeoutMs)
+{
+    if (prefixLen_ < 0 || prefixLen_ > 32) {
+        Logger::error("Invalid prefix length in LocalPingScanner constructor");
+        throw std::runtime_error("Bad prefix length");
+    }
+    if (timeoutMs_ <= 0) {
+        timeoutMs_ = 2000;
+    }
+}
+
+const std::vector<std::string> &LocalPingScanner::alive() const
+{
+    return alive_;
+}
+
+uint32_t LocalPingScanner::ipToU32(const std::string &ip)
+{
+    using namespace boost::asio::ip;
+    return static_cast<uint32_t>(make_address_v4(ip).to_uint());
+}
+
+std::string LocalPingScanner::u32ToIp(uint32_t v)
+{
+    using namespace boost::asio::ip;
+    return address_v4(v).to_string();
+}
+
+bool LocalPingScanner::pingHost(const std::string &ip) const
+{
+    try {
+        return Poco::Net::ICMPClient::pingIPv4(
+                   ip,
+                   /*repeat=*/1,
+                   /*dataSize=*/48,
+                   /*ttl=*/64,
+                   /*timeout=*/timeoutMs_
+               )
+               > 0;
+    } catch (const std::exception &ex) {
+        Logger::error(
+            std::string("Ping failed for host ") + ip + ": " + ex.what()
+        );
+        return false;
+    } catch (...) {
+        Logger::fatal(std::string("Unknown error pinging host ") + ip);
+        return false;
+    }
+}
+
+void LocalPingScanner::runImpl()
+{
+    alive_.clear();
+
+    const uint32_t base = ipToU32(baseIp_);
+    const uint32_t mask =
+        (prefixLen_ == 0) ? 0u : (0xFFFFFFFFu << (32 - prefixLen_));
+    const uint32_t network = base & mask;
+    const uint32_t broadcast = network | (~mask);
+
+    // No hosts when prefix is too tight (e.g., /32).
+    if (broadcast - network <= 2) {
+        return;
+    }
+
+    const std::string selfIp = u32ToIp(base);
+
+    for (uint32_t v = network + 1; v < broadcast; ++v) {
+        const std::string ipStr = u32ToIp(v);
+
+        if (ipStr == selfIp) {
+            continue;
+        }
+
+        if (pingHost(ipStr)) {
+            alive_.push_back(ipStr);
+        }
+    }
+}
+
+void LocalPingScanner::run()
+{
+    try {
+        runImpl();
+    } catch (const std::exception &ex) {
+        Logger::error(
+            std::string("Exception in LocalPingScanner::run: ") + ex.what()
+        );
+    } catch (...) {
+        Logger::fatal("Unknown exception in LocalPingScanner::run");
+    }
+}
diff --git a/src/core/local_ping_scanner.hpp b/src/core/local_ping_scanner.hpp
new file mode 100644
index 0000000..e41ffb6
--- /dev/null
+++ b/src/core/local_ping_scanner.hpp
@@ -0,0 +1,26 @@
+#pragma once
+#include <cstdint>
+#include <string>
+#include <vector>
+
+class LocalPingScanner
+{
+  public:
+    LocalPingScanner(
+        const std::string &baseIp, int prefixLen, int timeoutMs = 2000
+    );
+
+    void run(); // blocking scan over subnet
+    const std::vector<std::string> &alive() const;
+
+  private:
+    static std::string u32ToIp(uint32_t v);
+    static uint32_t ipToU32(const std::string &ip);
+    bool pingHost(const std::string &ip) const;
+    void runImpl();
+
+    std::string baseIp_;
+    int prefixLen_;
+    int timeoutMs_;
+    std::vector<std::string> alive_;
+};