Merge pull request #4534 from DataDog/munir/fix-128-trace-id-validations

fix(datadog-headers): ignore invalid tid values in x-datadog-tags

Author: mabdinur

lib/datadog/tracing/distributed/datadog.rb

@@ -116,6 +116,8 @@ def build_tags(digest)
         def extract_trace_id!(trace_id, tags)
           return trace_id unless tags
           return trace_id unless (high_order = tags.delete(Tracing::Metadata::Ext::Distributed::TAG_TID))
+          return trace_id unless high_order.size == 16
+          return trace_id unless /\A[0-9a-f]+\z/i.match?(high_order)
 
           Tracing::Utils::TraceId.concatenate(high_order.to_i(16), trace_id)
         end

spec/datadog/tracing/distributed/datadog_spec.rb

@@ -503,6 +503,28 @@
       it { expect(digest.span_id).to eq(0xbbbbbbbbbbbbbbbb) }
       it { expect(digest.trace_distributed_tags).not_to include('_dd.p.tid') }
     end
+
+    context 'with a trace id and an invalid distributed tags `_dd.p.tid`' do
+      [
+        '00123456789abcdef', # too long
+        '234567890abcdef', # too short
+        'g123456789abcdef', # invalid character
+      ].each do |invalid_trace_id|
+        context "when given invalid trace_id: #{invalid_trace_id}" do
+          let(:data) do
+            {
+              prepare_key['x-datadog-trace-id'] => 0xffffffffffffffff.to_s,
+              prepare_key['x-datadog-parent-id'] => 0xbbbbbbbbbbbbbbbb.to_s,
+              prepare_key['x-datadog-tags'] => "_dd.p.tid= #{invalid_trace_id}"
+            }
+          end
+
+          it { expect(digest.trace_id).to eq(0xffffffffffffffff) }
+          it { expect(digest.span_id).to eq(0xbbbbbbbbbbbbbbbb) }
+          it { expect(digest.trace_distributed_tags).not_to include('_dd.p.tid') }
+        end
+      end
+    end
   end
 end