Add (hacky) possibility of handling of EADDRINUSE

Author: SolraBizna

netsock.cc

@@ -92,6 +92,7 @@ static const char* inet_ntop(int af, const void* src, char* dst, DWORD cnt) {
 # define WSAEINTR EINTR
 # define WSAEINPROGRESS EINPROGRESS
 # define WSAEMSGSIZE EMSGSIZE
+# define WSAEADDRINUSE EADDRINUSE
 #endif
 
 static const char* error_string(int err = last_error) {
@@ -116,6 +117,8 @@ static bool have_inited_sockets = false;
 static WSADATA wsaData;
 #endif
 
+const std::string Sock::ADDRESS_IN_USE = "Unable to bind: Address already in use";
+
 static void init_sockets() {
   have_inited_sockets = true;
 #ifdef __WIN32__
@@ -593,7 +596,11 @@ bool ServerSock::SubBind(std::string& error_out, const char* bind_address,
   case IPVersion::V6: addr.in6.sin6_port = htons(port); break;
   }
   if(bind(sock, &addr.faceless, addr.Length())) {
-    error_out = std::string("Unable to bind: ") + error_string();
+    int err = last_error;
+    if(err == WSAEADDRINUSE)
+      error_out = ADDRESS_IN_USE;
+    else
+      error_out = std::string("Unable to bind: ") + error_string(last_error);
     Close();
     return false;
   }

netsock.hh

@@ -123,6 +123,10 @@ namespace Net {
               bool blocking = false);
     void Become(SOCKET sock, bool blocking = false);
   public:
+    // If a Bind function puts this exact value into error_out, EADDRINUSE has
+    // occurred. The bind may succeed if you wait and retry.
+    // Special handling of this is NOT required.
+    static const std::string ADDRESS_IN_USE;
     inline Sock(Sock&& other) {
       if(&other == this) return;
       sock = other.sock;