Revised Avahi client integration in mDNS client:

- aligned state handling with avahi-browse tool: browser is started in client callback
- browsing is limited to IPv4 services discovered on the specific daemon network interface only
Additional minor changes.

daemon/browser.cpp

@@ -35,11 +35,11 @@ std::shared_ptr<Browser> Browser::create(
   return ptr;
 }
 
-std::list<RemoteSource> Browser::get_remote_sources() {
+std::list<RemoteSource> Browser::get_remote_sources() const {
   std::list<RemoteSource> sources_list;
   std::shared_lock sources_lock(sources_mutex_);
   // return list of remote sources ordered by name
-  for (auto& source: sources_.get<name_tag>()) {
+  for (const auto& source: sources_.get<name_tag>()) {
     sources_list.push_back(source);
   }
   return sources_list;

daemon/browser.hpp

@@ -61,12 +61,12 @@ class Browser : public MDNSClient {
   bool init() override;
   bool terminate() override;
 
-  std::list<RemoteSource> get_remote_sources();
+  std::list<RemoteSource> get_remote_sources() const;
 
  protected:
   // singleton, use create() to build
   Browser(std::shared_ptr<Config> config):
-      config_(config),
+      MDNSClient(config),
       startup_(std::chrono::steady_clock::now()){};
 
   bool worker();
@@ -79,7 +79,6 @@ class Browser : public MDNSClient {
                    const std::string& name,
                    const std::string& domain) override;
 
-  std::shared_ptr<Config> config_;
   std::future<bool> res_;
   std::atomic_bool running_{false};
 

daemon/config.cpp

@@ -95,6 +95,13 @@ std::shared_ptr<Config> Config::parse(const std::string& filename) {
   }
   config.ip_addr_ = ip_addr;
   config.ip_str_ = ip_str;
+  auto interface_idx = get_interface_index(config.interface_name_);
+  if (interface_idx < 0) {
+    std::cerr << "Cannot retrieve index for interface "
+              << config.interface_name_ << std::endl;
+    return nullptr;
+  }
+  config.interface_idx_ = interface_idx;
   config.config_filename_ = filename;
   config.need_restart_ = false;
 

daemon/config.hpp

@@ -57,7 +57,8 @@ class Config {
   uint32_t get_ip_addr() const { return ip_addr_; };
   const std::string& get_ip_addr_str() const { return ip_str_; };
   bool get_need_restart() const { return need_restart_; };
-  bool get_mdns_enabled() const { return mdns_enabled; };
+  bool get_mdns_enabled() const { return mdns_enabled_; };
+  int get_interface_idx() { return interface_idx_; };
 
   void set_http_port(uint16_t http_port) { http_port_ = http_port; };
   void set_http_base_dir(const std::string& http_base_dir) { http_base_dir_ = http_base_dir; };
@@ -103,8 +104,9 @@ class Config {
     mac_addr_ = mac_addr;
   };
   void set_mdns_enabled(bool enabled) {
-    mdns_enabled = enabled;
+    mdns_enabled_ = enabled;
   };
+  void set_interface_idx(int index) { interface_idx_ = index; };
 
  private:
   /* from json */
@@ -125,13 +127,14 @@ class Config {
   std::string syslog_server_{""};
   std::string status_file_{"./status.json"};
   std::string interface_name_{"eth0"};
-  bool mdns_enabled{true};
+  bool mdns_enabled_{true};
 
   /* set during init */
   std::array<uint8_t, 6> mac_addr_{0, 0, 0, 0, 0, 0};
   std::string mac_str_;
   uint32_t ip_addr_{0};
   std::string ip_str_;
+  int interface_idx_;
   std::string config_filename_;
 
   /* reconfig needs daemon restart */

daemon/interface.cpp

@@ -48,8 +48,8 @@ std::pair<uint32_t, std::string> get_interface_ip(
       reinterpret_cast<struct sockaddr_in*>(&ifr.ifr_addr);
   uint32_t addr = ntohl(sockaddr->sin_addr.s_addr);
   std::string str_addr(ip::address_v4(addr).to_string());
-  /*BOOST_LOG_TRIVIAL(debug) << "interface " << interface_name << " IP address "
+  /*BOOST_LOG_TRIVIAL(debug) << "interface " << interface_name
-                          << str_addr;*/
+                             << " IP address " << str_addr;*/
 
   return std::make_pair(addr, str_addr);
 }
@@ -81,8 +81,31 @@ std::pair<std::array<uint8_t, 6>, std::string> get_interface_mac(
   char str_mac[18];
   sprintf(str_mac, "%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
           mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
-  /*BOOST_LOG_TRIVIAL(debug) << "interface " << interface_name << " MAC address "
+  /*BOOST_LOG_TRIVIAL(debug) << "interface " << interface_name
-                          << str_mac;*/
+                             << " MAC address " << str_mac;*/
 
   return std::make_pair(mac, str_mac);
 }
+
+int get_interface_index(const std::string& interface_name) {
+  int fd = socket(AF_INET, SOCK_DGRAM, 0);
+  if (fd < 0) {
+    BOOST_LOG_TRIVIAL(error)
+        << "Cannot retrieve index for interface " << interface_name;
+    return -1;
+  }
+  struct ifreq ifr;
+  ifr.ifr_addr.sa_family = AF_INET;
+  strncpy(ifr.ifr_name, interface_name.c_str(), IFNAMSIZ - 1);
+  if (ioctl(fd, SIOCGIFADDR, &ifr) < 0) {
+    close(fd);
+    BOOST_LOG_TRIVIAL(error)
+        << "Cannot retrieve index for interface " << interface_name;
+    return -1;
+  }
+  close(fd);
+  /*BOOST_LOG_TRIVIAL(debug) << "interface " << interface_name
+                             << " index " << ifr.ifr_ifindex;*/
+
+  return ifr.ifr_ifindex;
+}

daemon/interface.hpp

@@ -24,5 +24,6 @@ std::pair<uint32_t, std::string> get_interface_ip(
     const std::string& interface_name);
 std::pair<std::array<uint8_t, 6>, std::string> get_interface_mac(
     const std::string& interface_name);
+int get_interface_index(const std::string& interface_name);
 
 #endif

daemon/mdns_client.cpp

@@ -22,6 +22,7 @@
 #include <boost/asio.hpp>
 
 #include "config.hpp"
+#include "interface.hpp"
 #include "log.hpp"
 #include "rtsp_client.hpp"
 
@@ -156,16 +157,40 @@ void MDNSClient::browse_callback(AvahiServiceBrowser* b,
   }
 }
 
-void MDNSClient::client_callback(AvahiClient* c,
+void MDNSClient::client_callback(AvahiClient* client,
                                  AvahiClientState state,
                                  void* userdata) {
   MDNSClient& mdns = *(reinterpret_cast<MDNSClient*>(userdata));
   /* Called whenever the client or server state changes */
-  if (state == AVAHI_CLIENT_FAILURE) {
+
+  switch (state) {
+  case AVAHI_CLIENT_FAILURE:
     BOOST_LOG_TRIVIAL(fatal) << "avahi_client:: server connection failure: "
-                             << avahi_strerror(avahi_client_errno(c));
+                             << avahi_strerror(avahi_client_errno(client));
+    /* TODO reconnect if disconnected */
     avahi_threaded_poll_quit(mdns.poll_.get());
+    break;
+
+   case AVAHI_CLIENT_S_REGISTERING:
+   case AVAHI_CLIENT_S_RUNNING:
+   case AVAHI_CLIENT_S_COLLISION:
+    /* Create the service browser */
+    mdns.sb_.reset(avahi_service_browser_new(client,
+                                        mdns.config_->get_interface_idx(),
+                                        AVAHI_PROTO_INET, "_rtsp._tcp", nullptr,
+                                        {}, browse_callback, &mdns));
+    if (mdns.sb_ == nullptr) {
+      BOOST_LOG_TRIVIAL(fatal)
+          << "avahi_client:: failed to create service browser: "
+          << avahi_strerror(avahi_client_errno(mdns.client_.get()));
+      avahi_threaded_poll_quit(mdns.poll_.get());
+    }
+    break;
+
+  case AVAHI_CLIENT_CONNECTING:
+    break;
   }
+
 }
 #endif
 
@@ -194,17 +219,6 @@ bool MDNSClient::init() {
     return false;
   }
 
-  /* Create the service browser */
-  sb_.reset(avahi_service_browser_new(client_.get(), AVAHI_IF_UNSPEC,
-                                      AVAHI_PROTO_UNSPEC, "_rtsp._tcp", nullptr,
-                                      {}, browse_callback, this));
-  if (sb_ == nullptr) {
-    BOOST_LOG_TRIVIAL(fatal)
-        << "avahi_client:: failed to create service browser: "
-        << avahi_strerror(avahi_client_errno(client_.get()));
-    return false;
-  }
-
   (void)avahi_threaded_poll_start(poll_.get());
 #endif
   running_ = true;

daemon/mdns_client.hpp

@@ -38,7 +38,8 @@
 
 class MDNSClient {
  public:
-  MDNSClient(){};
+  MDNSClient(std::shared_ptr<Config> config): config_(config){};
+  MDNSClient() = delete;
   MDNSClient(const MDNSClient&) = delete;
   MDNSClient& operator=(const MDNSClient&) = delete;
   virtual ~MDNSClient() { terminate(); };
@@ -93,6 +94,8 @@ class MDNSClient {
   static void client_callback(AvahiClient* c,
                               AvahiClientState state,
                               void* userdata);
+
+  std::shared_ptr<Config> config_;
 #endif
 };