Show error dialog when ZeroTier fails

Fixes #2708

Source/DiabloUI/selgame.cpp

@@ -478,7 +478,10 @@ void selgame_Password_Select(int /*value*/)
 			selgame_endMenu = true;
 		} else {
 			selgame_Free();
-			UiSelOkDialog(_("Multi Player Game"), SDL_GetError(), false);
+			std::string error = SDL_GetError();
+			if (error.empty())
+				error = "Unknown network error";
+			UiSelOkDialog(_("Multi Player Game"), error.c_str(), false);
 			LoadBackgroundArt("ui_art\\selgame.pcx");
 			selgame_Password_Init(selgame_selectedGame);
 		}
@@ -496,7 +499,10 @@ void selgame_Password_Select(int /*value*/)
 		selgame_endMenu = true;
 	} else {
 		selgame_Free();
-		UiSelOkDialog(_("Multi Player Game"), SDL_GetError(), false);
+		std::string error = SDL_GetError();
+		if (error.empty())
+			error = "Unknown network error";
+		UiSelOkDialog(_("Multi Player Game"), error.c_str(), false);
 		LoadBackgroundArt("ui_art\\selgame.pcx");
 		selgame_Password_Init(0);
 	}

Source/dvlnet/base_protocol.h

@@ -129,8 +129,7 @@ int base_protocol<P>::create(std::string addrstr)
 		plr_self = 0;
 		connected_table[plr_self] = true;
 	}
-
-	return (plr_self == PLR_BROADCAST ? MAX_PLRS : plr_self);
+	return (plr_self == PLR_BROADCAST ? -1 : plr_self);
 }
 
 template <class P>
@@ -140,7 +139,8 @@ int base_protocol<P>::join(std::string addrstr)
 	if (wait_network())
 		if (wait_firstpeer())
 			wait_join();
-	return (plr_self == PLR_BROADCAST ? MAX_PLRS : plr_self);
+
+	return (plr_self == PLR_BROADCAST ? -1 : plr_self);
 }
 
 template <class P>

Source/dvlnet/protocol_zt.cpp

@@ -63,6 +63,7 @@ bool protocol_zt::network_online()
 		auto ret = lwip_bind(fd_udp, (struct sockaddr *)&in6, sizeof(in6));
 		if (ret < 0) {
 			Log("lwip, (udp) bind: {}", strerror(errno));
+			SDL_SetError("lwip, (udp) bind: %s", strerror(errno));
 			throw protocol_exception();
 		}
 		set_nonblock(fd_udp);
@@ -73,11 +74,13 @@ bool protocol_zt::network_online()
 		auto r1 = lwip_bind(fd_tcp, (struct sockaddr *)&in6, sizeof(in6));
 		if (r1 < 0) {
 			Log("lwip, (tcp) bind: {}", strerror(errno));
+			SDL_SetError("lwip, (udp) bind: %s", strerror(errno));
 			throw protocol_exception();
 		}
 		auto r2 = lwip_listen(fd_tcp, 10);
 		if (r2 < 0) {
 			Log("lwip, listen: {}", strerror(errno));
+			SDL_SetError("lwip, listen: %s", strerror(errno));
 			throw protocol_exception();
 		}
 		set_nonblock(fd_tcp);
@@ -209,6 +212,7 @@ bool protocol_zt::accept_all()
 		std::copy(in6.sin6_addr.s6_addr, in6.sin6_addr.s6_addr + 16, ep.addr.begin());
 		if (peer_list[ep].fd != -1) {
 			Log("protocol_zt::accept_all: WARNING: overwriting connection");
+			SDL_SetError("protocol_zt::accept_all: WARNING: overwriting connection");
 			lwip_close(peer_list[ep].fd);
 		}
 		set_nonblock(newfd);
@@ -258,6 +262,7 @@ void protocol_zt::disconnect(const endpoint &peer)
 		if (peer_list[peer].fd != -1) {
 			if (lwip_close(peer_list[peer].fd) < 0) {
 				Log("lwip_close: {}", strerror(errno));
+				SDL_SetError("lwip_close: %s", strerror(errno));
 			}
 		}
 		peer_list.erase(peer);