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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include <array>
#include "detail/hex.h"
#include "detail/string.h"
#include "opentelemetry/context/propagation/text_map_propagator.h"
#include "opentelemetry/nostd/function_ref.h"
#include "opentelemetry/nostd/shared_ptr.h"
#include "opentelemetry/nostd/span.h"
#include "opentelemetry/nostd/string_view.h"
#include "opentelemetry/trace/context.h"
#include "opentelemetry/trace/default_span.h"
#include "opentelemetry/version.h"
OPENTELEMETRY_BEGIN_NAMESPACE
namespace trace
{
namespace propagation
{
static const nostd::string_view kTraceParent = "traceparent";
static const nostd::string_view kTraceState = "tracestate";
static const size_t kVersionSize = 2;
static const size_t kTraceIdSize = 32;
static const size_t kSpanIdSize = 16;
static const size_t kTraceFlagsSize = 2;
static const size_t kTraceParentSize = 55;
// The HttpTraceContext provides methods to extract and inject
// context into headers of HTTP requests with traces.
// Example:
// HttpTraceContext().Inject(carrier, context);
// HttpTraceContext().Extract(carrier, context);
class HttpTraceContext : public context::propagation::TextMapPropagator
{
public:
void Inject(context::propagation::TextMapCarrier &carrier,
const context::Context &context) noexcept override
{
SpanContext span_context = trace::GetSpan(context)->GetContext();
if (!span_context.IsValid())
{
return;
}
InjectImpl(carrier, span_context);
}
context::Context Extract(const context::propagation::TextMapCarrier &carrier,
context::Context &context) noexcept override
{
SpanContext span_context = ExtractImpl(carrier);
nostd::shared_ptr<Span> sp{new DefaultSpan(span_context)};
if (span_context.IsValid())
{
return trace::SetSpan(context, sp);
}
else
{
return context;
}
}
static TraceId TraceIdFromHex(nostd::string_view trace_id)
{
uint8_t buf[kTraceIdSize / 2];
detail::HexToBinary(trace_id, buf, sizeof(buf));
return TraceId(buf);
}
static SpanId SpanIdFromHex(nostd::string_view span_id)
{
uint8_t buf[kSpanIdSize / 2];
detail::HexToBinary(span_id, buf, sizeof(buf));
return SpanId(buf);
}
static TraceFlags TraceFlagsFromHex(nostd::string_view trace_flags)
{
uint8_t flags;
detail::HexToBinary(trace_flags, &flags, sizeof(flags));
return TraceFlags(flags);
}
private:
static constexpr uint8_t kInvalidVersion = 0xFF;
static constexpr uint8_t kDefaultAssumedVersion = 0x00;
static void InjectImpl(context::propagation::TextMapCarrier &carrier,
const SpanContext &span_context)
{
char trace_parent[kTraceParentSize];
trace_parent[0] = '0';
trace_parent[1] = '0';
trace_parent[2] = '-';
span_context.trace_id().ToLowerBase16(
nostd::span<char, 2 * TraceId::kSize>{&trace_parent[3], kTraceIdSize});
trace_parent[kTraceIdSize + 3] = '-';
span_context.span_id().ToLowerBase16(
nostd::span<char, 2 * SpanId::kSize>{&trace_parent[kTraceIdSize + 4], kSpanIdSize});
trace_parent[kTraceIdSize + kSpanIdSize + 4] = '-';
span_context.trace_flags().ToLowerBase16(
nostd::span<char, 2>{&trace_parent[kTraceIdSize + kSpanIdSize + 5], 2});
carrier.Set(kTraceParent, nostd::string_view(trace_parent, sizeof(trace_parent)));
const auto trace_state = span_context.trace_state()->ToHeader();
if (!trace_state.empty())
{
carrier.Set(kTraceState, trace_state);
}
}
static SpanContext ExtractContextFromTraceHeaders(nostd::string_view trace_parent,
nostd::string_view trace_state)
{
std::array<nostd::string_view, 4> fields{};
if (detail::SplitString(trace_parent, '-', fields.data(), 4) != 4)
{
return SpanContext::GetInvalid();
}
nostd::string_view version_hex = fields[0];
nostd::string_view trace_id_hex = fields[1];
nostd::string_view span_id_hex = fields[2];
nostd::string_view trace_flags_hex = fields[3];
if (version_hex.size() != kVersionSize || trace_id_hex.size() != kTraceIdSize ||
span_id_hex.size() != kSpanIdSize || trace_flags_hex.size() != kTraceFlagsSize)
{
return SpanContext::GetInvalid();
}
if (!detail::IsValidHex(version_hex) || !detail::IsValidHex(trace_id_hex) ||
!detail::IsValidHex(span_id_hex) || !detail::IsValidHex(trace_flags_hex))
{
return SpanContext::GetInvalid();
}
// hex is valid, convert it to binary
uint8_t version_binary;
detail::HexToBinary(version_hex, &version_binary, sizeof(version_binary));
if (version_binary == kInvalidVersion)
{
// invalid version encountered
return SpanContext::GetInvalid();
}
// See https://www.w3.org/TR/trace-context/#versioning-of-traceparent
if (version_binary > kDefaultAssumedVersion)
{
// higher than default version detected
if (trace_parent.size() < kTraceParentSize)
{
return SpanContext::GetInvalid();
}
}
else
{
// version is either lower or same as the default version
if (trace_parent.size() != kTraceParentSize)
{
return SpanContext::GetInvalid();
}
}
TraceId trace_id = TraceIdFromHex(trace_id_hex);
SpanId span_id = SpanIdFromHex(span_id_hex);
if (!trace_id.IsValid() || !span_id.IsValid())
{
return SpanContext::GetInvalid();
}
return SpanContext(trace_id, span_id, TraceFlagsFromHex(trace_flags_hex), true,
trace::TraceState::FromHeader(trace_state));
}
static SpanContext ExtractImpl(const context::propagation::TextMapCarrier &carrier)
{
// Get trace_parent after trimming the leading and trailing whitespaces
nostd::string_view trace_parent = common::StringUtil::Trim(carrier.Get(kTraceParent));
nostd::string_view trace_state = carrier.Get(kTraceState);
if (trace_parent == "")
{
return SpanContext::GetInvalid();
}
return ExtractContextFromTraceHeaders(trace_parent, trace_state);
}
bool Fields(nostd::function_ref<bool(nostd::string_view)> callback) const noexcept override
{
return (callback(kTraceParent) && callback(kTraceState));
}
};
} // namespace propagation
} // namespace trace
OPENTELEMETRY_END_NAMESPACE
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