e1608: scan review fixes (EINTR in Scan::poll, cfg-based broadcast test, no per-tick copy)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/source/e1608/e1608_kind.cpp

@@ -233,22 +233,22 @@ void hook_entry(GtkWidget* w, const FormPtr& f) {
 constexpr int kScanMs = 1500;  ///< how long a scan listens
 constexpr int kTickMs = 50;    ///< how often it drains the sockets
 
-/// A result row's two ways to name the board, with the form they fill.
+/// A result row's two ways to name the board: what each fills into the form (the other is cleared).
 struct Pick {
   FormPtr form;
-  std::string ip, mac;
+  std::string value;
 };
 
 void free_pick(gpointer d, GClosure*) { delete static_cast<Pick*>(d); }
 
 void on_pick_address(AdwActionRow*, gpointer user) {
   Pick& p = *static_cast<Pick*>(user);
-  p.form->fill(p.ip, "");
+  p.form->fill(p.value, "");
 }
 
 void on_pick_mac(GtkButton*, gpointer user) {
   Pick& p = *static_cast<Pick*>(user);
-  p.form->fill("", p.mac);
+  p.form->fill("", p.value);
 }
 
 void add_result(const FormPtr& f, const DeviceInfo& d) {
@@ -263,8 +263,8 @@ void add_result(const FormPtr& f, const DeviceInfo& d) {
   gtk_widget_set_valign(use_mac, GTK_ALIGN_CENTER);
   adw_action_row_add_suffix(ADW_ACTION_ROW(row), use_mac);
   g_signal_connect_data(row, "activated", G_CALLBACK(on_pick_address),
-                        new Pick{f, d.ip, mac}, free_pick, static_cast<GConnectFlags>(0));
-  g_signal_connect_data(use_mac, "clicked", G_CALLBACK(on_pick_mac), new Pick{f, d.ip, mac},
+                        new Pick{f, d.ip}, free_pick, static_cast<GConnectFlags>(0));
+  g_signal_connect_data(use_mac, "clicked", G_CALLBACK(on_pick_mac), new Pick{f, mac},
                         free_pick, static_cast<GConnectFlags>(0));
   adw_expander_row_add_row(ADW_EXPANDER_ROW(f->scan_row), row);
   adw_expander_row_set_expanded(ADW_EXPANDER_ROW(f->scan_row), TRUE);
@@ -284,7 +284,7 @@ gboolean on_scan_tick(gpointer user) {
     f.timer = 0;
     return G_SOURCE_REMOVE;
   }
-  const std::vector<DeviceInfo> found = f.scan->poll();
+  const auto& found = f.scan->poll();  // valid until f.scan.reset() below, after its last use
   while (f.results.size() < found.size()) add_result(fp, found[f.results.size()]);
   f.scan_ms += kTickMs;
   if (f.scan_ms < kScanMs) return G_SOURCE_CONTINUE;

src/source/e1608/e1608_link.cpp

@@ -291,7 +291,10 @@ const std::vector<DeviceInfo>& Scan::poll() {
       socklen_t flen = sizeof from;
       const ssize_t n = ::recvfrom(s.get(), buf, sizeof buf, MSG_DONTWAIT,
                                    reinterpret_cast<sockaddr*>(&from), &flen);
-      if (n < 0) break;  // nothing more on this socket for now
+      if (n < 0) {
+        if (errno == EINTR) continue;
+        break;  // nothing more on this socket for now
+      }
       take_reply(buf, n, from, found_);
     }
   }

src/source/e1608/e1608_source.cpp

@@ -272,15 +272,15 @@ void E1608Source::connect_and_start() {
   Mac want{};
   const bool have_mac = !cfg_.mac_text.empty() && parse_mac(cfg_.mac_text, want);
   if (host.empty() || have_mac) {
-    const std::vector<std::string> targets =
-        host.empty() ? sweep_targets(cfg_.subnet) : std::vector<std::string>{host};
     const int wait_ms = std::min(cfg_.timeout_ms, 1500);
     // No address and no subnet: the limited broadcast, sent on every interface rather than only
     // the default route's.
-    const bool broadcast =
-        host.empty() && targets.size() == 1 && targets[0] == "255.255.255.255";
+    const bool broadcast = host.empty() && cfg_.subnet.empty();
     const std::vector<DeviceInfo> found =
-        broadcast ? discover_broadcast(cfg_.port, wait_ms) : discover(targets, cfg_.port, wait_ms);
+        broadcast ? discover_broadcast(cfg_.port, wait_ms)
+                  : discover(host.empty() ? sweep_targets(cfg_.subnet)
+                                          : std::vector<std::string>{host},
+                             cfg_.port, wait_ms);
     if (host.empty()) {
       for (const DeviceInfo& d : found) {
         if (d.mac == want) host = d.ip;