From 449da2b53ee492b1c50f100ec1178b01343ff340 Mon Sep 17 00:00:00 2001
From: tearfur <46261767+tearfur@users.noreply.github.com>
Date: Wed, 5 Jul 2023 05:33:58 +0800
Subject: [PATCH] fix: assert failure when Transmission quit with pending IP
 queries (#5721)

---
 libtransmission/global-ip-cache.cc | 46 ++++++++++++++++++------------
 1 file changed, 28 insertions(+), 18 deletions(-)

diff --git a/libtransmission/global-ip-cache.cc b/libtransmission/global-ip-cache.cc
index ea69c6128..25f4adfda 100644
--- a/libtransmission/global-ip-cache.cc
+++ b/libtransmission/global-ip-cache.cc
@@ -33,13 +33,6 @@ static_assert(TR_AF_INET6 == 1);
 
 auto TR_CONSTEXPR23 protocol_str(tr_address_type type) noexcept
 {
-    /* TODO: very slight performance nit
-     * - If upgrading to C++20, change Map to a consteval lambda:
-     *   static auto Map = []() consteval { return std::array{ "IPv4"sv, "IPv6"sv }; };
-     * - If upgrading to C++23, change Map to static constexpr
-     *
-     * Ref: https://wg21.link/p2647r1
-     */
     static auto TR_CONSTEXPR23 map = std::array{ "IPv4"sv, "IPv6"sv };
     return map[type];
 }
@@ -50,6 +43,10 @@ auto constexpr IPQueryServices = std::array{ std::array{ "https://ip4.transmissi
 auto constexpr UpkeepInterval = 30min;
 auto constexpr RetryUpkeepInterval = 30s;
 
+// Normally there should only ever be 1 cache instance during the entire program execution
+// This is a counter only to cater for SessionTest.honorsSettings
+std::size_t cache_exists = 0;
+
 } // namespace
 
 namespace
@@ -147,6 +144,8 @@ tr_global_ip_cache::tr_global_ip_cache(Mediator& mediator_in)
         upkeep_timers_[i]->set_callback(cb);
         start_timer(type, UpkeepInterval);
     }
+
+    ++cache_exists;
 }
 
 std::unique_ptr<tr_global_ip_cache> tr_global_ip_cache::create(tr_global_ip_cache::Mediator& mediator_in)
@@ -161,10 +160,15 @@ tr_global_ip_cache::~tr_global_ip_cache()
                                          global_addr_mutex_[TR_AF_INET], global_addr_mutex_[TR_AF_INET6],
                                          source_addr_mutex_[TR_AF_INET], source_addr_mutex_[TR_AF_INET6] };
 
-    TR_ASSERT(std::all_of(
-        std::begin(is_updating_),
-        std::end(is_updating_),
-        [](is_updating_t const& v) { return v == is_updating_t::ABORT; }));
+    if (std::all_of(
+            std::begin(is_updating_),
+            std::end(is_updating_),
+            [](is_updating_t const& v) { return v == is_updating_t::ABORT; }))
+    {
+        tr_logAddDebug("Destructed while some global IP queries were pending.");
+    }
+
+    --cache_exists;
 }
 
 bool tr_global_ip_cache::try_shutdown() noexcept
@@ -238,7 +242,13 @@ void tr_global_ip_cache::update_global_addr(tr_address_type type) noexcept
                                                       tr_web::FetchOptions::IPProtocol::V6 };
     auto options = tr_web::FetchOptions{ IPQueryServices[type][ix_service_[type]],
                                          [this, type](tr_web::FetchResponse const& response)
-                                         { this->on_response_ip_query(type, response); },
+                                         {
+                                             // Check to avoid segfault
+                                             if (cache_exists != 0)
+                                             {
+                                                 this->on_response_ip_query(type, response);
+                                             }
+                                         },
                                          nullptr };
     options.ip_proto = IPProtocolMap[type];
     options.sndbuf = 4096;
@@ -312,14 +322,14 @@ void tr_global_ip_cache::on_response_ip_query(tr_address_type type, tr_web::Fetc
     }
 
     // Try next IP query URL
-    if (!success && ++ix_service_[type] < std::size(IPQueryServices[type]))
-    {
-        update_global_addr(type);
-        return;
-    }
-
     if (!success)
     {
+        if (++ix_service_[type] < std::size(IPQueryServices[type]))
+        {
+            update_global_addr(type);
+            return;
+        }
+
         tr_logAddDebug(fmt::format("Couldn't obtain global {} address", protocol));
         unset_global_addr(type);
         upkeep_timers_[type]->set_interval(RetryUpkeepInterval);