net: introduce Sock::WaitMany()

It allows waiting concurrently on more than one socket. Being a
`virtual` `Sock` method it can be overriden by tests.

Will be used to replace `CConnman::SocketEvents()`.

src/test/fuzz/util.cpp

@@ -223,6 +223,15 @@ bool FuzzedSock::Wait(std::chrono::milliseconds timeout, Event requested, Event*
     return true;
 }
 
+bool FuzzedSock::WaitMany(std::chrono::milliseconds timeout, EventsPerSock& events_per_sock) const
+{
+    for (auto& [sock, events] : events_per_sock) {
+        (void)sock;
+        events.occurred = m_fuzzed_data_provider.ConsumeBool() ? events.requested : 0;
+    }
+    return true;
+}
+
 bool FuzzedSock::IsConnected(std::string& errmsg) const
 {
     if (m_fuzzed_data_provider.ConsumeBool()) {

src/test/fuzz/util.h

@@ -72,6 +72,8 @@ public:
 
     bool Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred = nullptr) const override;
 
+    bool WaitMany(std::chrono::milliseconds timeout, EventsPerSock& events_per_sock) const override;
+
     bool IsConnected(std::string& errmsg) const override;
 };
 

src/test/util/net.h

@@ -162,6 +162,15 @@ public:
         return true;
     }
 
+    bool WaitMany(std::chrono::milliseconds timeout, EventsPerSock& events_per_sock) const override
+    {
+        for (auto& [sock, events] : events_per_sock) {
+            (void)sock;
+            events.occurred = events.requested;
+        }
+        return true;
+    }
+
 private:
     const std::string m_contents;
     mutable size_t m_consumed;