Grcov report - span_context

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#include "source/extensions/tracers/opentelemetry/span_context_extractor.h"

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#include "envoy/tracing/tracer.h"

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#include "source/common/http/header_map_impl.h"

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#include "source/common/tracing/trace_context_impl.h"

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#include "source/extensions/tracers/opentelemetry/span_context.h"

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#include "absl/strings/escaping.h"

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namespace Envoy {

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namespace Extensions {

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namespace Tracers {

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namespace OpenTelemetry {

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namespace {

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// See https://www.w3.org/TR/trace-context/#traceparent-header

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constexpr int kTraceparentHeaderSize = 55; // 2 + 1 + 32 + 1 + 16 + 1 + 2

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constexpr int kVersionHexSize = 2;

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constexpr int kTraceIdHexSize = 32;

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constexpr int kParentIdHexSize = 16;

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constexpr int kTraceFlagsHexSize = 2;

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bool isValidHex(const absl::string_view& input) {

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  return std::all_of(input.begin(), input.end(),

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                     [](const char& c) { return absl::ascii_isxdigit(c); });

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bool isAllZeros(const absl::string_view& input) {

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  return std::all_of(input.begin(), input.end(), [](const char& c) { return c == '0'; });

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} // namespace

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SpanContextExtractor::SpanContextExtractor(Tracing::TraceContext& trace_context)

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    : trace_context_(trace_context) {}

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SpanContextExtractor::~SpanContextExtractor() = default;

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bool SpanContextExtractor::propagationHeaderPresent() {

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  auto propagation_header = OpenTelemetryConstants::get().TRACE_PARENT.get(trace_context_);

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  return propagation_header.has_value();

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absl::StatusOr<SpanContext> SpanContextExtractor::extractSpanContext() {

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  auto propagation_header = OpenTelemetryConstants::get().TRACE_PARENT.get(trace_context_);

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  if (!propagation_header.has_value()) {

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    // We should have already caught this, but just in case.

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    return absl::InvalidArgumentError("No propagation header found");

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  auto header_value_string = propagation_header.value();

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  if (header_value_string.size() != kTraceparentHeaderSize) {

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    return absl::InvalidArgumentError("Invalid traceparent header length");

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  // Try to split it into its component parts:

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  std::vector<absl::string_view> propagation_header_components =

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      absl::StrSplit(header_value_string, '-', absl::SkipEmpty());

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  if (propagation_header_components.size() != 4) {

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    return absl::InvalidArgumentError("Invalid traceparent hyphenation");

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  absl::string_view version = propagation_header_components[0];

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  absl::string_view trace_id = propagation_header_components[1];

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  absl::string_view span_id = propagation_header_components[2];

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  absl::string_view trace_flags = propagation_header_components[3];

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  if (version.size() != kVersionHexSize || trace_id.size() != kTraceIdHexSize ||

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      span_id.size() != kParentIdHexSize || trace_flags.size() != kTraceFlagsHexSize) {

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    return absl::InvalidArgumentError("Invalid traceparent field sizes");

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  if (!isValidHex(version) || !isValidHex(trace_id) || !isValidHex(span_id) ||

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      !isValidHex(trace_flags)) {

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    return absl::InvalidArgumentError("Invalid header hex");

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  // As per the traceparent header definition, if the trace-id or parent-id are all zeros, they are

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  // invalid and must be ignored.

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  if (isAllZeros(trace_id)) {

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    return absl::InvalidArgumentError("Invalid trace id");

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  if (isAllZeros(span_id)) {

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    return absl::InvalidArgumentError("Invalid parent id");

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  // Set whether or not the span is sampled from the trace flags.

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  // See https://w3c.github.io/trace-context/#trace-flags.

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  char decoded_trace_flags = absl::HexStringToBytes(trace_flags).front();

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  bool sampled = (decoded_trace_flags & 1);

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  // If a tracestate header is received without an accompanying traceparent header,

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  // it is invalid and MUST be discarded. Because we're already checking for the

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  // traceparent header above, we don't need to check here.

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  // See https://www.w3.org/TR/trace-context/#processing-model-for-working-with-trace-context

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  const auto tracestate_values = OpenTelemetryConstants::get().TRACE_STATE.getAll(trace_context_);

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  SpanContext parent_context(version, trace_id, span_id, sampled,

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                             absl::StrJoin(tracestate_values, ","));

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  return parent_context;

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} // namespace OpenTelemetry

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} // namespace Tracers

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} // namespace Extensions

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} // namespace Envoy