print ip of connected master

Author: NikolasK-source

src/Modbus_TCP_Slave.cpp

@@ -6,8 +6,11 @@
 #include "Modbus_TCP_Slave.hpp"
 
 #include <algorithm>
+#include <arpa/inet.h>
+#include <cstring>
 #include <netinet/in.h>
 #include <netinet/tcp.h>
+#include <sstream>
 #include <stdexcept>
 #include <sys/socket.h>
 #include <system_error>
@@ -107,12 +110,29 @@ void Slave::set_debug(bool debug) {
     }
 }
 
-void Slave::connect_client() {
+std::string Slave::connect_client() {
     int tmp = modbus_tcp_accept(modbus, &socket);
     if (tmp < 0) {
         const std::string error_msg = modbus_strerror(errno);
         throw std::runtime_error("modbus_tcp_accept failed: " + error_msg);
     }
+
+    struct sockaddr_in peer_addr;
+    socklen_t          len = sizeof(peer_addr);
+    tmp = getpeername(modbus_get_socket(modbus), reinterpret_cast<struct sockaddr *>(&peer_addr), &len);
+
+    if (tmp < 0) {
+        const std::string error_msg = modbus_strerror(errno);
+        throw std::runtime_error("getpeername failed: " + error_msg);
+    }
+
+    char buffer[INET_ADDRSTRLEN];
+    inet_ntop(peer_addr.sin_family, &peer_addr.sin_addr, buffer, sizeof(buffer));
+
+    std::ostringstream sstr;
+    sstr << buffer << ':' << htons(peer_addr.sin_port);
+
+    return sstr.str();
 }
 
 bool Slave::handle_request() {

src/Modbus_TCP_Slave.hpp

@@ -44,8 +44,9 @@ class Slave {
 
     /*! \brief wait for client to connect
      *
+     * @return ip of the connected client
      */
-    void connect_client();
+    std::string connect_client();
 
     /*! \brief wait for request from Master and generate reply
      *

src/main.cpp

@@ -88,18 +88,18 @@ int main(int argc, char **argv) {
                          ("m,monitor",
                           "output all incoming and outgoing packets to stdout")
                          ("r,reconnect",
-                          "do not terminate if Master disconnects.")
+                          "do not terminate if the Modbus master disconnects.")
                          ("byte-timeout",
                           "timeout interval in seconds between two consecutive bytes of the same message. "
-                           "In most cases it is sufficient to set teh response timeout. "
+                           "In most cases it is sufficient to set the response timeout. "
                            "Fractional values are possible.",
                           cxxopts::value<double>())
                          ("response-timeout",
                           "set the timeout interval in seconds used to wait for a response. "
-                          "When a byte timeout is set, if elapsed time for the first byte of response is longer than "
-                          "the given timeout, a timeout is detected. "
+                          "When a byte timeout is set, if the elapsed time for the first byte of response is longer "
+                          "than the given timeout, a timeout is detected. "
                           "When byte timeout is disabled, the full confirmation response must be received before "
-                          "expiration of the response timeout."
+                          "expiration of the response timeout. "
                           "Fractional values are possible.",
                           cxxopts::value<double>())
 #ifdef OS_LINUX
@@ -231,8 +231,9 @@ int main(int argc, char **argv) {
     do {
         // connect client
         std::cerr << "Waiting for Master to establish a connection..." << std::endl;
+        std::string client;
         try {
-            slave->connect_client();
+            client = slave->connect_client();
         } catch (const std::runtime_error &e) {
             if (!terminate) {
                 std::cerr << e.what() << std::endl;
@@ -241,7 +242,7 @@ int main(int argc, char **argv) {
             break;
         }
 
-        std::cerr << "Master established connection." << std::endl;
+        std::cerr << "Master (" << client << ") established connection." << std::endl;
 
         // ========== MAIN LOOP ========== (handle requests)
         bool connection_closed = false;