encode_opentelemetry: Handle minimal otel payloads

Signed-off-by: Hiroshi Hatake <hiroshi@chronosphere.io>

src/ctr_encode_opentelemetry.c

@@ -917,11 +917,21 @@ static Opentelemetry__Proto__Common__V1__InstrumentationScope *set_instrumentati
         return NULL;
     }
 
-    otel_scope->name = instrumentation_scope->name;
-    otel_scope->version = instrumentation_scope->version;
+    if (instrumentation_scope->name) {
+        otel_scope->name = instrumentation_scope->name;
+    }
+    else {
+        otel_scope->name = "";
+    }
+    if (instrumentation_scope->version) {
+        otel_scope->version = instrumentation_scope->version;
+    }
+    else {
+        otel_scope->version = "";
+    }
     otel_scope->n_attributes = get_attributes_count(instrumentation_scope->attr);
     otel_scope->dropped_attributes_count = instrumentation_scope->dropped_attr_count;
-    otel_scope->attributes = set_attributes_from_ctr(instrumentation_scope->attr);;
+    otel_scope->attributes = set_attributes_from_ctr(instrumentation_scope->attr);
 
     return otel_scope;
 }
@@ -989,7 +999,9 @@ static Opentelemetry__Proto__Trace__V1__ScopeSpans **set_scope_spans(struct ctra
         }
 
         otel_scope_span->schema_url = scope_span->schema_url;
-        otel_scope_span->scope = set_instrumentation_scope(scope_span->instrumentation_scope);
+        if (scope_span->instrumentation_scope != NULL) {
+            otel_scope_span->scope = set_instrumentation_scope(scope_span->instrumentation_scope);
+        }
 
         span_count = cfl_list_size(&scope_span->spans);
         otel_scope_span->n_spans = span_count;

tests/decoding.c

@@ -429,6 +429,81 @@ static struct ctrace *generate_encoder_test_data()
     return context;
 }
 
+static int generate_sample_resource_minimal_attributes(struct ctrace_resource *resource)
+{
+    struct ctrace_attributes *attributes;
+    int                       result;
+
+    attributes = ctr_attributes_create();
+
+    if (attributes == NULL) {
+        return -1;
+    }
+
+    result = ctr_attributes_set_string(attributes, "receiver.tool", "ctraces");
+
+    if (result != 0) {
+        ctr_attributes_destroy(attributes);
+
+        return -2;
+    }
+
+    result = ctr_resource_set_attributes(resource, attributes);
+
+    if (result != 0) {
+        ctr_attributes_destroy(attributes);
+
+        return -3;
+    }
+
+    return 0;
+}
+
+static struct ctrace *generate_encoder_test_data_with_empty_spans()
+{
+    struct ctrace_resource_span *resource_span;
+    struct ctrace_scope_span    *scope_span;
+    struct ctrace               *context;
+    int                          result;
+
+    context = ctr_create(NULL);
+
+    if (context == NULL) {
+        return NULL;
+    }
+
+    resource_span = ctr_resource_span_create(context);
+
+    if (resource_span == NULL) {
+        ctr_destroy(context);
+
+        return NULL;
+    }
+
+    ctr_resource_span_set_schema_url(resource_span, "");
+    ctr_resource_set_dropped_attr_count(resource_span->resource, 0);
+
+    result = generate_sample_resource_minimal_attributes(resource_span->resource);
+
+    if (result != 0) {
+        ctr_destroy(context);
+
+        return NULL;
+    }
+
+    scope_span = ctr_scope_span_create(resource_span);
+
+    if (scope_span == NULL) {
+        ctr_destroy(context);
+
+        return NULL;
+    }
+
+    ctr_scope_span_set_schema_url(scope_span, "");
+
+    return context;
+}
+
 /*
  * perform the following and then compare text buffers
  *
@@ -483,6 +558,23 @@ void test_msgpack_to_cmt()
     ctr_destroy(context);
 }
 
+void test_msgpack_to_ctr_with_empty_spans()
+{
+    struct ctrace *context;
+    char          *referece_text_buffer;
+
+    context = generate_encoder_test_data_with_empty_spans();
+    TEST_ASSERT(context != NULL);
+
+    referece_text_buffer = ctr_encode_text_create(context);
+    TEST_ASSERT(referece_text_buffer != NULL);
+
+    printf("%s\n", referece_text_buffer);
+    msgpack_encode_decode_and_compare(context);
+
+    ctr_destroy(context);
+}
+
 void test_simple_to_msgpack_and_back()
 {
     struct ctrace *ctx;
@@ -640,5 +732,6 @@ void test_simple_to_msgpack_and_back()
 TEST_LIST = {
     {"cmt_simple_to_msgpack_and_back", test_simple_to_msgpack_and_back},
     {"cmt_msgpack",                    test_msgpack_to_cmt},
+    {"empty_spans",                    test_msgpack_to_ctr_with_empty_spans},
     { 0 }
 };