From 62e480fed714d003ab83b398cfb9820ea4968b2d Mon Sep 17 00:00:00 2001
From: hg <4683435+hgtw@users.noreply.github.com>
Date: Sat, 30 Jan 2021 18:31:19 -0500
Subject: [PATCH] Verify expedition is not empty on invites

Fixes an edge case where a member could accept a pending invite into an
empty expedition before world could invalidate it
---
 zone/expedition.cpp | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/zone/expedition.cpp b/zone/expedition.cpp
index f75b09c3f..cf9ebc0c1 100644
--- a/zone/expedition.cpp
+++ b/zone/expedition.cpp
@@ -781,11 +781,19 @@ bool Expedition::ProcessAddConflicts(Client* leader_client, Client* add_client,
 		}
 	}
 
-	// swapping ignores the max player count check since it's a 1:1 change
-	if (!swapping && ExpeditionDatabase::GetMemberCount(m_id) >= m_max_players)
+	// member swapping integrity is handled by invite response
+	if (!swapping)
 	{
-		SendLeaderMessage(leader_client, Chat::Red, DZADD_EXCEED_MAX, { fmt::format_int(m_max_players).str() });
-		has_conflict = true;
+		auto member_count = ExpeditionDatabase::GetMemberCount(m_id);
+		if (member_count == 0)
+		{
+			has_conflict = true;
+		}
+		else if (member_count >= m_max_players)
+		{
+			SendLeaderMessage(leader_client, Chat::Red, DZADD_EXCEED_MAX, { fmt::format_int(m_max_players).str() });
+			has_conflict = true;
+		}
 	}
 
 	auto invite_id = add_client->GetPendingExpeditionInviteID();