From 48f3ade8bdf81f3e63d26ddb1f4529fcff38b77f Mon Sep 17 00:00:00 2001
From: Daniel Widgren <daniel.widgren@gmail.com>
Date: Sun, 24 May 2026 11:41:17 +0200
Subject: [PATCH] debug: logger=debug + try/catch verify_signature

Two complementary changes to surface what is actually going wrong
with webhook verification:

1. prod logger_level: info -> debug. Wider net so nothing is filtered.
2. Wrap gakudan_tickets_github:verify_signature/3 in try/catch with a
   ?LOG_ERROR that captures the crash class/reason/stack and the byte
   sizes of secret/body/sig. crypto:hash_equals/2 raises badarg when
   the two binaries differ in size; without this wrap the handler
   crashes and Nova renders a generic 500, which is what we just saw
   when probing with a short test signature. Real GitHub deliveries
   should not hit this, but the safety net + error log will tell us
   immediately if they do for some reason.
---
 config/prod_sys.config.src                     |  2 +-
 .../triagebot_webhook_controller.erl           | 18 +++++++++++++++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/config/prod_sys.config.src b/config/prod_sys.config.src
index 699b53d..19f3e97 100644
--- a/config/prod_sys.config.src
+++ b/config/prod_sys.config.src
@@ -1,6 +1,6 @@
 [
     {kernel, [
-        {logger_level, info},
+        {logger_level, debug},
         {logger, [
             {handler, default, logger_std_h, #{
                 formatter => {nova_jsonlogger, #{
diff --git a/src/controllers/triagebot_webhook_controller.erl b/src/controllers/triagebot_webhook_controller.erl
index ef32925..5a50187 100644
--- a/src/controllers/triagebot_webhook_controller.erl
+++ b/src/controllers/triagebot_webhook_controller.erl
@@ -28,7 +28,23 @@ github_event(Req) ->
     EventType = cowboy_req:header(~"x-github-event", Req1, ~""),
     Delivery = cowboy_req:header(~"x-github-delivery", Req1, ~""),
     Secret = triagebot_config:webhook_secret(),
-    case gakudan_tickets_github:verify_signature(Secret, Sig, Body) of
+    Valid =
+        try
+            gakudan_tickets_github:verify_signature(Secret, Sig, Body)
+        catch
+            Class:Reason:Stack ->
+                ?LOG_ERROR(#{
+                    event => verify_signature_crashed,
+                    class => Class,
+                    reason => Reason,
+                    stack => Stack,
+                    sig_byte_size => byte_size(Sig),
+                    secret_byte_size => byte_size(Secret),
+                    body_byte_size => byte_size(Body)
+                }),
+                false
+        end,
+    case Valid of
         false ->
             ?LOG_WARNING(#{
                 event => webhook_signature_invalid,