From 9a17d3411db3ee41c9b8f1ff998c8f4474b7e9a0 Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Thu, 9 Oct 2025 14:53:51 +0200
Subject: [PATCH] dnsdist: Properly handle exceptions when processing timeout
 rules

Signed-off-by: Remi Gacogne <remi.gacogne@powerdns.com>
---
 pdns/dnsdistdist/dnsdist.cc | 72 +++++++++++++++++++++----------------
 1 file changed, 42 insertions(+), 30 deletions(-)

diff --git a/pdns/dnsdistdist/dnsdist.cc b/pdns/dnsdistdist/dnsdist.cc
index a1e58df1c7..c06c42acf5 100644
--- a/pdns/dnsdistdist/dnsdist.cc
+++ b/pdns/dnsdistdist/dnsdist.cc
@@ -1611,7 +1611,14 @@ bool handleTimeoutResponseRules(const std::vector<dnsdist::rules::ResponseRuleAc
       return false;
     }
   }
-  (void)applyRulesToResponse(rules, dnsResponse);
+
+  try {
+    (void)applyRulesToResponse(rules, dnsResponse);
+  }
+  catch (const std::exception& exp) {
+    vinfolog("Exception while processing timeout response rules: %s", exp.what());
+  }
+
   return dnsResponse.isAsynchronous();
 }
 
@@ -2425,45 +2432,50 @@ static void healthChecksThread()
     .tv_usec = 0};
 
   for (;;) {
-    checkExiting();
+    try {
+      checkExiting();
 
-    timeval now{};
-    gettimeofday(&now, nullptr);
-    auto elapsedTimeUsec = uSec(now - lastRound);
-    if (elapsedTimeUsec < intervalUsec) {
-      usleep(intervalUsec - elapsedTimeUsec);
-      gettimeofday(&lastRound, nullptr);
-    }
-    else {
-      lastRound = now;
-    }
+      timeval now{};
+      gettimeofday(&now, nullptr);
+      auto elapsedTimeUsec = uSec(now - lastRound);
+      if (elapsedTimeUsec < intervalUsec) {
+        usleep(intervalUsec - elapsedTimeUsec);
+        gettimeofday(&lastRound, nullptr);
+      }
+      else {
+        lastRound = now;
+      }
 
-    std::unique_ptr<FDMultiplexer> mplexer{nullptr};
-    const auto& runtimeConfig = dnsdist::configuration::refreshLocalRuntimeConfiguration();
+      std::unique_ptr<FDMultiplexer> mplexer{nullptr};
+      const auto& runtimeConfig = dnsdist::configuration::refreshLocalRuntimeConfiguration();
 
-    // this points to the actual shared_ptrs!
-    // coverity[auto_causes_copy]
-    const auto servers = runtimeConfig.d_backends;
-    for (const auto& dss : servers) {
-      dss->updateStatisticsInfo();
+      // this points to the actual shared_ptrs!
+      // coverity[auto_causes_copy]
+      const auto servers = runtimeConfig.d_backends;
+      for (const auto& dss : servers) {
+        dss->updateStatisticsInfo();
 
-      dss->handleUDPTimeouts();
+        dss->handleUDPTimeouts();
 
-      if (!dss->healthCheckRequired()) {
-        continue;
-      }
+        if (!dss->healthCheckRequired()) {
+          continue;
+        }
+
+        if (!mplexer) {
+          mplexer = std::unique_ptr<FDMultiplexer>(FDMultiplexer::getMultiplexerSilent(servers.size()));
+        }
 
-      if (!mplexer) {
-        mplexer = std::unique_ptr<FDMultiplexer>(FDMultiplexer::getMultiplexerSilent(servers.size()));
+        if (!queueHealthCheck(mplexer, dss)) {
+          dss->submitHealthCheckResult(false, false);
+        }
       }
 
-      if (!queueHealthCheck(mplexer, dss)) {
-        dss->submitHealthCheckResult(false, false);
+      if (mplexer) {
+        handleQueuedHealthChecks(*mplexer);
       }
     }
-
-    if (mplexer) {
-      handleQueuedHealthChecks(*mplexer);
+    catch (const std::exception& exp) {
+      vinfolog("Exception in the health-check thread: %s", exp.what());
     }
   }
 }
-- 
2.47.3