network: Rework initial interface search by using a dump

Instead of using an alternative way to list all links in order to
choose one when an "interface" is in the configuration, we can ask for
a dump of all interface an reuse the handleEvents() function.

This patch also start to rework the handleEvents() function to grab
more information out of each event, like the interface name.

include/modules/network.hpp

@@ -28,8 +28,11 @@ class Network : public ALabel {
   static const uint8_t EPOLL_MAX = 200;
 
   static int handleEvents(struct nl_msg*, void*);
+  static int handleEventsDone(struct nl_msg*, void*);
   static int handleScan(struct nl_msg*, void*);
 
+  void askForStateDump(void);
+
   void              worker();
   void              createInfoSocket();
   void              createEventSocket();
@@ -59,6 +62,9 @@ class Network : public ALabel {
   int                nl80211_id_;
   std::mutex         mutex_;
 
+  bool               want_link_dump_;
+  bool               dump_in_progress_;
+
   unsigned long long bandwidth_down_total_;
   unsigned long long bandwidth_up_total_;
 

src/modules/network.cpp

@@ -86,6 +86,8 @@ waybar::modules::Network::Network(const std::string &id, const Json::Value &conf
       family_(config["family"] == "ipv6" ? AF_INET6 : AF_INET),
       efd_(-1),
       ev_fd_(-1),
+      want_link_dump_(false),
+      dump_in_progress_(false),
       cidr_(0),
       signal_strength_dbm_(0),
       signal_strength_(0),
@@ -114,6 +116,11 @@ waybar::modules::Network::Network(const std::string &id, const Json::Value &conf
     bandwidth_up_total_ = 0;
   }
 
+  if (config_["interface"].isString()) {
+    // Look for an interface that match "interface"
+    want_link_dump_ = true;
+  }
+
   createEventSocket();
   createInfoSocket();
   auto default_iface = getPreferredIface(-1, false);
@@ -125,6 +132,10 @@ waybar::modules::Network::Network(const std::string &id, const Json::Value &conf
     getInterfaceAddress();
   }
   dp.emit();
+  // Ask for a dump of interfaces and then addresses to populate our
+  // information. First the interface dump, and once done, the callback
+  // will be called again which will ask for addresses dump.
+  askForStateDump();
   worker();
 }
 
@@ -155,6 +166,7 @@ void waybar::modules::Network::createEventSocket() {
   ev_sock_ = nl_socket_alloc();
   nl_socket_disable_seq_check(ev_sock_);
   nl_socket_modify_cb(ev_sock_, NL_CB_VALID, NL_CB_CUSTOM, handleEvents, this);
+  nl_socket_modify_cb(ev_sock_, NL_CB_FINISH, NL_CB_CUSTOM, handleEventsDone, this);
   auto groups = RTMGRP_LINK | (family_ == AF_INET ? RTMGRP_IPV4_IFADDR : RTMGRP_IPV6_IFADDR);
   nl_join_groups(ev_sock_, groups);  // Deprecated
   if (nl_connect(ev_sock_, NETLINK_ROUTE) != 0) {
@@ -590,29 +602,9 @@ bool waybar::modules::Network::checkInterface(struct ifinfomsg *rtif, std::strin
 int waybar::modules::Network::getPreferredIface(int skip_idx, bool wait) const {
   int ifid = -1;
   if (config_["interface"].isString()) {
-    ifid = if_nametoindex(config_["interface"].asCString());
-    if (ifid > 0) {
-      return ifid;
-    } else {
-      // Try with wildcard
-      struct ifaddrs *ifaddr, *ifa;
-      int             success = getifaddrs(&ifaddr);
-      if (success != 0) {
+    // Using link dump instead
     return -1;
   }
-      ifa = ifaddr;
-      ifid = -1;
-      while (ifa != nullptr) {
-        if (wildcardMatch(config_["interface"].asString(), ifa->ifa_name)) {
-          ifid = if_nametoindex(ifa->ifa_name);
-          break;
-        }
-        ifa = ifa->ifa_next;
-      }
-      freeifaddrs(ifaddr);
-      return ifid;
-    }
-  }
   // getExternalInterface may need some delay to detect external interface
   for (uint8_t tries = 0; tries < MAX_RETRY; tries += 1) {
     ifid = getExternalInterface(skip_idx);
@@ -656,6 +648,55 @@ int waybar::modules::Network::handleEvents(struct nl_msg *msg, void *data) {
   std::lock_guard<std::mutex> lock(net->mutex_);
   auto                        nh = nlmsg_hdr(msg);
   auto                        ifi = static_cast<struct ifinfomsg *>(NLMSG_DATA(nh));
+  bool                        is_del_event = false;
+
+  switch (nh->nlmsg_type) {
+  case RTM_DELLINK:
+    is_del_event = true;
+  case RTM_NEWLINK: {
+    struct ifinfomsg *ifi = static_cast<struct ifinfomsg *>(NLMSG_DATA(nh));
+    ssize_t attrlen = IFLA_PAYLOAD(nh);
+    struct rtattr *ifla = IFLA_RTA(ifi);
+    const char *ifname = NULL;
+    size_t ifname_len = 0;
+
+    if (net->ifid_ != -1 && ifi->ifi_index != net->ifid_) {
+      return NL_OK;
+    }
+
+    for (; RTA_OK(ifla, attrlen); ifla = RTA_NEXT(ifla, attrlen)) {
+      switch (ifla->rta_type) {
+      case IFLA_IFNAME:
+        ifname = static_cast<const char *>(RTA_DATA(ifla));
+        ifname_len = RTA_PAYLOAD(ifla) - 1; // minus \0
+        break;
+      }
+    }
+
+    if (!is_del_event && net->ifid_ == -1) {
+      // Checking if it's an interface we care about.
+      std::string new_ifname (ifname, ifname_len);
+      if (net->checkInterface(ifi, new_ifname)) {
+        spdlog::debug("network: selecting new interface {}/{}", new_ifname, ifi->ifi_index);
+
+        net->ifname_ = new_ifname;
+        net->ifid_ = ifi->ifi_index;
+        net->getInterfaceAddress();
+        net->thread_timer_.wake_up();
+      }
+    } else if (is_del_event && net->ifid_ >= 0) {
+      // Our interface has been deleted, start looking/waiting for one we care.
+      spdlog::debug("network: interface {}/{} deleted", net->ifname_, net->ifid_);
+
+      net->clearIface();
+      // Check for a new interface and get info
+      net->checkNewInterface(ifi);
+      net->dp.emit();
+    }
+    return NL_OK;
+  }
+  }
+
   if (nh->nlmsg_type == RTM_DELADDR) {
     // Check for valid interface
     if (ifi->ifi_index == net->ifid_) {
@@ -671,25 +712,6 @@ int waybar::modules::Network::handleEvents(struct nl_msg *msg, void *data) {
       }
       return NL_OK;
     }
-  } else if (nh->nlmsg_type == RTM_NEWLINK || nh->nlmsg_type == RTM_DELLINK) {
-    char ifname[IF_NAMESIZE];
-    if_indextoname(ifi->ifi_index, ifname);
-    // Check for valid interface
-    if (ifi->ifi_index != net->ifid_ && net->checkInterface(ifi, ifname)) {
-      net->ifname_ = ifname;
-      net->ifid_ = ifi->ifi_index;
-      // Get Iface and WIFI info
-      net->getInterfaceAddress();
-      net->thread_timer_.wake_up();
-      return NL_OK;
-    } else if (ifi->ifi_index == net->ifid_ &&
-               (!(ifi->ifi_flags & IFF_RUNNING) || !(ifi->ifi_flags & IFF_UP) ||
-                !net->checkInterface(ifi, ifname))) {
-      net->clearIface();
-      // Check for a new interface and get info
-      net->checkNewInterface(ifi);
-      return NL_OK;
-    }
   } else {
     char ifname[IF_NAMESIZE];
     if_indextoname(ifi->ifi_index, ifname);
@@ -713,6 +735,32 @@ int waybar::modules::Network::handleEvents(struct nl_msg *msg, void *data) {
   return NL_SKIP;
 }
 
+void waybar::modules::Network::askForStateDump(void) {
+  /* We need to wait until the current dump is done before sending new
+   * messages. handleEventsDone() is called when a dump is done. */
+  if (dump_in_progress_)
+    return;
+
+  struct rtgenmsg rt_hdr = {
+    .rtgen_family = AF_UNSPEC,
+  };
+
+  if (want_link_dump_) {
+    nl_send_simple(ev_sock_, RTM_GETLINK, NLM_F_DUMP,
+                   &rt_hdr, sizeof (rt_hdr));
+    want_link_dump_ = false;
+    dump_in_progress_ = true;
+
+  }
+}
+
+int waybar::modules::Network::handleEventsDone(struct nl_msg *msg, void *data) {
+  auto net = static_cast<waybar::modules::Network *>(data);
+  net->dump_in_progress_ = false;
+  net->askForStateDump();
+  return NL_OK;
+}
+
 int waybar::modules::Network::handleScan(struct nl_msg *msg, void *data) {
   auto              net = static_cast<waybar::modules::Network *>(data);
   auto              gnlh = static_cast<genlmsghdr *>(nlmsg_data(nlmsg_hdr(msg)));