resolve net device host during connect (fixes #336)

src/lib/ebus/device.cpp

@@ -74,21 +74,10 @@ Device* Device::create(const char* name, bool checkDevice, bool readOnly, bool i
       free(in);
       return nullptr;  // invalid port
     }
-    struct sockaddr_in address;
-    memset(reinterpret_cast<char*>(&address), 0, sizeof(address));
     *portpos = 0;
-    if (inet_aton(addrpos, &address.sin_addr) == 0) {
+    char* hostOrIp = strdup(addrpos);
-      struct hostent* h = gethostbyname(addrpos);
-      if (h == nullptr) {
-        free(in);
-        return nullptr;  // invalid host
-      }
-      memcpy(&address.sin_addr, h->h_addr_list[0], h->h_length);
-    }
     free(in);
-    address.sin_family = AF_INET;
+    return new NetworkDevice(name, hostOrIp, port, readOnly, initialSend, udp);
-    address.sin_port = (in_port_t)htons((uint16_t)port);
-    return new NetworkDevice(name, address, readOnly, initialSend, udp);
   }
   return new SerialDevice(name, checkDevice, readOnly, initialSend);
 }
@@ -296,13 +285,24 @@ result_t NetworkDevice::open() {
   if (m_fd != -1) {
     close();
   }
+  struct sockaddr_in address;
+  memset(reinterpret_cast<char*>(&address), 0, sizeof(address));
+  if (inet_aton(m_hostOrIp, &address.sin_addr) == 0) {
+    struct hostent* h = gethostbyname(m_hostOrIp);
+    if (h == nullptr) {
+      return RESULT_ERR_GENERIC_IO;  // invalid host
+    }
+    memcpy(&address.sin_addr, h->h_addr_list[0], h->h_length);
+  }
+  address.sin_family = AF_INET;
+  address.sin_port = (in_port_t)htons(m_port);
+
   m_fd = socket(AF_INET, m_udp ? SOCK_DGRAM : SOCK_STREAM, 0);
   if (m_fd < 0) {
     return RESULT_ERR_GENERIC_IO;
   }
   int ret;
   if (m_udp) {
-    struct sockaddr_in address = m_address;
     address.sin_addr.s_addr = INADDR_ANY;
     ret = bind(m_fd, (struct sockaddr*)&address, sizeof(address));
   } else {
@@ -318,7 +318,7 @@ result_t NetworkDevice::open() {
     setsockopt(m_fd, IPPROTO_TCP, TCP_KEEPCNT, reinterpret_cast<void*>(&value), sizeof(value));
   }
   if (ret >= 0) {
-    ret = connect(m_fd, (struct sockaddr*)&m_address, sizeof(m_address));
+    ret = connect(m_fd, (struct sockaddr*)&address, sizeof(address));
   }
   if (ret < 0) {
     close();

src/lib/ebus/device.h

@@ -237,19 +237,23 @@ class NetworkDevice : public Device {
    * Construct a new instance.
    * @param name the device name (e.g. "/dev/ttyUSB0" for serial, "127.0.0.1:1234" for network).
    * @param address the socket address of the device.
+   * @param hostOrIp the host name or IP address of the device.
+   * @param port the TCP or UDP port of the device.
    * @param readOnly whether to allow read access to the device only.
    * @param initialSend whether to send an initial @a ESC symbol in @a open().
    * @param udp true for UDP, false to TCP.
    */
-  NetworkDevice(const char* name, const struct sockaddr_in& address, bool readOnly, bool initialSend,
+  NetworkDevice(const char* name, const char* hostOrIp, uint16_t port, bool readOnly, bool initialSend, bool udp)
-    bool udp)
+    : Device(name, true, readOnly, initialSend), m_hostOrIp(hostOrIp), m_port(port), m_udp(udp),
-    : Device(name, true, readOnly, initialSend), m_address(address), m_udp(udp),
       m_buffer(nullptr), m_bufSize(0), m_bufLen(0), m_bufPos(0) {}
 
   /**
    * Destructor.
    */
   virtual ~NetworkDevice() {
+    if (m_hostOrIp) {
+      free((void*)m_hostOrIp);
+    }
     if (m_buffer) {
       free(m_buffer);
     }
@@ -279,8 +283,11 @@ class NetworkDevice : public Device {
 
 
  private:
-  /** the socket address of the device. */
+  /** the host name or IP address of the device. */
-  const struct sockaddr_in m_address;
+  const char* m_hostOrIp;
+
+  /** the TCP or UDP port of the device. */
+  const uint16_t m_port;
 
   /** true for UDP, false to TCP. */
   const bool m_udp;