more socket options

Author: NikolasK-git

src/Modbus_TCP_Slave.cpp

@@ -17,7 +17,7 @@ namespace TCP {
 
 static constexpr int MAX_REGS = 0x10000;
 
-Slave::Slave(const std::string &ip, unsigned short port, modbus_mapping_t *mapping) {
+Slave::Slave(const std::string &ip, unsigned short port, modbus_mapping_t *mapping, std::size_t tcp_timeout) {
     // create modbus object
     modbus = modbus_new_tcp(ip.c_str(), static_cast<int>(port));
     if (modbus == nullptr) {
@@ -54,10 +54,30 @@ Slave::Slave(const std::string &ip, unsigned short port, modbus_mapping_t *mappi
         throw std::system_error(errno, std::generic_category(), "Failed to set socket option SO_KEEPALIVE");
     }
 
-    unsigned user_timeout = 5000;
-    tmp                   = setsockopt(socket, IPPROTO_TCP, TCP_USER_TIMEOUT, &keepalive, sizeof(user_timeout));
-    if (tmp != 0) {
-        throw std::system_error(errno, std::generic_category(), "Failed to set socket option SO_KEEPALIVE");
+    if (tcp_timeout) {
+        unsigned user_timeout = static_cast<unsigned>(tcp_timeout) * 1000;
+        tmp                   = setsockopt(socket, IPPROTO_TCP, TCP_USER_TIMEOUT, &user_timeout, sizeof(keepalive));
+        if (tmp != 0) {
+            throw std::system_error(errno, std::generic_category(), "Failed to set socket option TCP_USER_TIMEOUT");
+        }
+
+        unsigned keepidle = 1;
+        tmp               = setsockopt(socket, IPPROTO_TCP, TCP_KEEPIDLE, &keepidle, sizeof(keepidle));
+        if (tmp != 0) {
+            throw std::system_error(errno, std::generic_category(), "Failed to set socket option TCP_KEEPIDLE");
+        }
+
+        unsigned keepintvl = 1;
+        tmp                = setsockopt(socket, IPPROTO_TCP, TCP_KEEPINTVL, &keepintvl, sizeof(keepintvl));
+        if (tmp != 0) {
+            throw std::system_error(errno, std::generic_category(), "Failed to set socket option TCP_KEEPINTVL");
+        }
+
+        unsigned keepcnt = static_cast<unsigned>(tcp_timeout);
+        tmp              = setsockopt(socket, IPPROTO_TCP, TCP_KEEPCNT, &keepcnt, sizeof(keepcnt));
+        if (tmp != 0) {
+            throw std::system_error(errno, std::generic_category(), "Failed to set socket option TCP_KEEPCNT");
+        }
     }
 }
 

src/Modbus_TCP_Slave.hpp

@@ -26,9 +26,10 @@ class Slave {
      * @param port port to listen  for incoming connections (default 502)
      * @param mapping modbus mapping object (nullptr: an mapping object with maximum size is generated)
      */
-    explicit Slave(const std::string &ip      = "0.0.0.0",
-                   short unsigned int port    = 502,
-                   modbus_mapping_t * mapping = nullptr);
+    explicit Slave(const std::string &ip          = "0.0.0.0",
+                   short unsigned int port        = 502,
+                   modbus_mapping_t * mapping     = nullptr,
+                   std::size_t        tcp_timeout = 5);
 
     /*! \brief destroy the modbus slave
      *

src/main.cpp

@@ -91,14 +91,17 @@ int main(int argc, char **argv) {
                            "In most cases it is sufficient to set teh response timeout. "
                            "Fractional values are possible.",
                           cxxopts::value<double>())
-                         ("t,response-timeout",
+                         ("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, the a timeout is detected."
                           "When byte timeout is disabled, the full confirmation response must be received before "
                           "expiration of the response timeout."
                           "Fractional values are possible.",
                           cxxopts::value<double>())
+                         ("t,tcp-timeout",
+                          "tcp timeout in seconds",
+                          cxxopts::value<std::size_t>()->default_value("5"))
                          ("h,help",
                           "print usage")
                          ("version",
@@ -178,8 +181,10 @@ int main(int argc, char **argv) {
     // create slave
     std::unique_ptr<Modbus::TCP::Slave> slave;
     try {
-        slave = std::make_unique<Modbus::TCP::Slave>(
-                args["ip"].as<std::string>(), args["port"].as<uint16_t>(), mapping.get_mapping());
+        slave = std::make_unique<Modbus::TCP::Slave>(args["ip"].as<std::string>(),
+                                                     args["port"].as<uint16_t>(),
+                                                     mapping.get_mapping(),
+                                                     args["tcp-timeout"].as<std::size_t>());
         slave->set_debug(args.count("monitor"));
     } catch (const std::runtime_error &e) {
         std::cerr << e.what() << std::endl;