Fix an antag rolling exploit

code/controllers/subsystem/jobs.dm

@@ -25,9 +25,9 @@ SUBSYSTEM_DEF(jobs)
 // Only fires every 5 minutes
 /datum/controller/subsystem/jobs/fire()
 	if(!config.sql_enabled || !config.use_exp_tracking)
-		return 
+		return
 	update_exp(5,0)
-	
+
 /datum/controller/subsystem/jobs/proc/SetupOccupations(var/list/faction = list("Station"))
 	occupations = list()
 	var/list/all_jobs = subtypesof(/datum/job)
@@ -284,7 +284,7 @@ SUBSYSTEM_DEF(jobs)
 
 	//Get the players who are ready
 	for(var/mob/new_player/player in GLOB.player_list)
-		if(player.ready && player.mind && !player.mind.assigned_role)
+		if(player.ready && player.has_valid_preferences() && player.mind && !player.mind.assigned_role)
 			unassigned += player
 			if(player.client.prefs.randomslot)
 				player.client.prefs.load_random_character_slot(player.client)

code/game/gamemodes/game_mode.dm

@@ -228,7 +228,7 @@
 
 	// Assemble a list of active players without jobbans.
 	for(var/mob/new_player/player in GLOB.player_list)
-		if(player.client && player.ready)
+		if(player.client && player.ready && player.has_valid_preferences())
 			if(!jobban_isbanned(player, "Syndicate") && !jobban_isbanned(player, roletext))
 				if(player_old_enough_antag(player.client,role))
 					players += player

code/modules/client/preference/preferences.dm

@@ -81,7 +81,7 @@ var/global/list/special_role_times = list( //minimum age (in days) for accounts
 	var/lastchangelog = ""				//Saved changlog filesize to detect if there was a change
 	var/exp
 	var/ooccolor = "#b82e00"
-	var/be_special = list()				//Special role selection
+	var/list/be_special = list()				//Special role selection
 	var/UI_style = "Midnight"
 	var/nanoui_fancy = TRUE
 	var/toggles = TOGGLES_DEFAULT
@@ -2280,3 +2280,7 @@ var/global/list/special_role_times = list( //minimum age (in days) for accounts
 
 /datum/preferences/proc/close_load_dialog(mob/user)
 	user << browse(null, "window=saves")
+
+//Check if the user has ANY job selected.
+/datum/preferences/proc/check_any_job()
+	return(job_support_high || job_support_med || job_support_low || job_medsci_high || job_medsci_med || job_medsci_low || job_engsec_high || job_engsec_med || job_engsec_low || job_karma_high || job_karma_med || job_karma_low)

code/modules/mob/mob_helpers.dm

@@ -641,5 +641,26 @@ var/list/intents = list(INTENT_HELP,INTENT_DISARM,INTENT_GRAB,INTENT_HARM)
 	// Cast to 1/0
 	return !!(client.prefs.toggles & toggleflag)
 
+// Used to make sure that a player has a valid job preference setup, used to knock players out of eligibility for anything if their prefs don't make sense.
+// A "valid job preference setup" in this situation means at least having one job set to low, or not having "return to lobby" enabled
+// Prevents "antag rolling" by setting antag prefs on, all jobs to never, and "return to lobby if preferences not availible"
+// Doing so would previously allow you to roll for antag, then send you back to lobby if you didn't get an antag role
+// This also does some admin notification and logging as well
+/mob/proc/has_valid_preferences()
+	if(!client)
+		return FALSE //Not sure how this would get run without the mob having a client, but let's just be safe.
+	if(client.prefs.alternate_option != RETURN_TO_LOBBY)
+		return TRUE
+	// If they have antags enabled, they're potentially doing this on purpose instead of by accident. Notify admins if so.
+	var/has_antags = FALSE
+	if(client.prefs.be_special.len > 0)
+		has_antags = TRUE
+	if(!client.prefs.check_any_job())
+		to_chat(src, "<span class='danger'>You have no jobs enabled, along with return to lobby if job is unavailable. This makes you ineligible for any round start role, please update your job preferences.</span>")
+		if(has_antags)
+			log_admin("[src.ckey] just got booted back to lobby with no jobs, but antags enabled.")
+			message_admins("[src.ckey] just got booted back to lobby with no jobs enabled, but antag rolling enabled. Likely antag rolling abuse.")
+		return FALSE //This is the only case someone should actually be completely blocked from antag rolling as well
+	return TRUE
 
 #define isterrorspider(A) (istype((A), /mob/living/simple_animal/hostile/poison/terror_spider))