Truncate Exception Messages if needed

CHANGELOG.md

@@ -1,6 +1,14 @@
 Changelog
 =========
 
+## TBD
+
+### Enhancements
+
+* Exception messages will be truncated if they have a length greater than 3,072
+  | [#636](https://github.com/bugsnag/bugsnag-ruby/pull/636)
+  | [joshuapinter](https://github.com/joshuapinter)
+
 ## 6.18.0 (27 October 2020)
 
 ### Enhancements

lib/bugsnag/helpers.rb

@@ -4,7 +4,7 @@
 
 
 module Bugsnag
-  module Helpers
+  module Helpers # rubocop:todo Metrics/ModuleLength
     MAX_STRING_LENGTH = 3072
     MAX_PAYLOAD_LENGTH = 512000
     MAX_ARRAY_LENGTH = 80
@@ -19,8 +19,12 @@ def self.trim_if_needed(value)
 
       return value unless payload_too_long?(value)
 
+      # Truncate exception messages
+      reduced_value = truncate_exception_messages(value)
+      return reduced_value unless payload_too_long?(reduced_value)
+
       # Trim metadata
-      reduced_value = trim_metadata(value)
+      reduced_value = trim_metadata(reduced_value)
       return reduced_value unless payload_too_long?(reduced_value)
 
       # Trim code from stacktrace
@@ -71,6 +75,15 @@ def self.deep_merge!(l_hash, r_hash)
 
     TRUNCATION_INFO = '[TRUNCATED]'
 
+    ##
+    # Truncate exception messages
+    def self.truncate_exception_messages(payload)
+      extract_exception(payload) do |exception|
+        exception[:message] = trim_as_string(exception[:message])
+      end
+      payload
+    end
+
     ##
     # Remove all code from stacktraces
     def self.trim_stacktrace_code(payload)

spec/helper_spec.rb

@@ -41,31 +41,75 @@
     end
 
     context "payload length is greater than allowed" do
+      it "trims exception messages" do
+        long_message = "should truncate" * 50000
+
+        payload = {
+          :events => [{
+            :exceptions => [{
+              :message => long_message,
+              :preserved => "Foo"
+            }]
+          }]
+        }
+
+        expect(::JSON.dump(payload).length).to be > Bugsnag::Helpers::MAX_PAYLOAD_LENGTH
+
+        trimmed = Bugsnag::Helpers.trim_if_needed(payload)
+
+        expect(::JSON.dump(trimmed).length).to be <= Bugsnag::Helpers::MAX_PAYLOAD_LENGTH
+
+        truncation_info = "[TRUNCATED]"
+        expected_length = Bugsnag::Helpers::MAX_STRING_LENGTH - truncation_info.length
+        expected_truncation = long_message[0...expected_length] + truncation_info
+
+        expect(trimmed[:events][0][:exceptions][0][:message]).to eq(expected_truncation)
+        expect(trimmed[:events][0][:exceptions][0][:preserved]).to eq("Foo")
+      end
+
       it "trims metadata strings" do
+        long_message = "should truncate" * 50000
+
         payload = {
           :events => [{
-            :metaData => 50000.times.map {|i| "should truncate" }.join(""),
+            :exceptions => [],
+            :metaData => long_message,
             :preserved => "Foo"
           }]
         }
+
         expect(::JSON.dump(payload).length).to be > Bugsnag::Helpers::MAX_PAYLOAD_LENGTH
+
         trimmed = Bugsnag::Helpers.trim_if_needed(payload)
+
         expect(::JSON.dump(trimmed).length).to be <= Bugsnag::Helpers::MAX_PAYLOAD_LENGTH
-        expect(trimmed[:events][0][:metaData].length).to be <= Bugsnag::Helpers::MAX_STRING_LENGTH
+
+        truncation_info = "[TRUNCATED]"
+        expected_length = Bugsnag::Helpers::MAX_STRING_LENGTH - truncation_info.length
+        expected_truncation = long_message[0...expected_length] + truncation_info
+
+        expect(trimmed[:events][0][:metaData]).to eq(expected_truncation)
         expect(trimmed[:events][0][:preserved]).to eq("Foo")
       end
 
       it "truncates metadata arrays" do
         payload = {
           :events => [{
+            :exceptions => [],
             :metaData => 50000.times.map {|i| "should truncate" },
             :preserved => "Foo"
           }]
         }
+
         expect(::JSON.dump(payload).length).to be > Bugsnag::Helpers::MAX_PAYLOAD_LENGTH
+
         trimmed = Bugsnag::Helpers.trim_if_needed(payload)
+
         expect(::JSON.dump(trimmed).length).to be <= Bugsnag::Helpers::MAX_PAYLOAD_LENGTH
-        expect(trimmed[:events][0][:metaData].length).to be <= Bugsnag::Helpers::MAX_ARRAY_LENGTH
+
+        expected_meta_data = payload[:events][0][:metaData].take(Bugsnag::Helpers::MAX_ARRAY_LENGTH)
+
+        expect(trimmed[:events][0][:metaData]).to eq(expected_meta_data)
         expect(trimmed[:events][0][:preserved]).to eq("Foo")
       end