1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
// 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/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 kB3CombinedHeader = "b3";
static const nostd::string_view kB3TraceIdHeader = "X-B3-TraceId";
static const nostd::string_view kB3SpanIdHeader = "X-B3-SpanId";
static const nostd::string_view kB3SampledHeader = "X-B3-Sampled";
/*
B3, single header:
b3: 80f198ee56343ba864fe8b2a57d3eff7-e457b5a2e4d86bd1-1-05e3ac9a4f6e3b90
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ ^ ^^^^^^^^^^^^^^^^
0 TraceId 31 33 SpanId 48 | 52 ParentSpanId 68
50 Debug flag
Multiheader version: X-B3-Sampled
X-B3-TraceId X-B3-SpanId X-B3-ParentSpanId (ignored)
*/
static const int kTraceIdHexStrLength = 32;
static const int kSpanIdHexStrLength = 16;
// The B3PropagatorExtractor class provides an interface that enables extracting context from
// headers of HTTP requests. HTTP frameworks and clients can integrate with B3Propagator by
// providing the object containing the headers, and a getter function for the extraction. Based on:
// https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/context/api-propagators.md#b3-extract
class B3PropagatorExtractor : public context::propagation::TextMapPropagator
{
public:
// Returns the context that is stored in the HTTP header carrier.
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[kTraceIdHexStrLength / 2];
detail::HexToBinary(trace_id, buf, sizeof(buf));
return TraceId(buf);
}
static SpanId SpanIdFromHex(nostd::string_view span_id)
{
uint8_t buf[kSpanIdHexStrLength / 2];
detail::HexToBinary(span_id, buf, sizeof(buf));
return SpanId(buf);
}
static TraceFlags TraceFlagsFromHex(nostd::string_view trace_flags)
{
if (trace_flags.length() != 1 || (trace_flags[0] != '1' && trace_flags[0] != 'd'))
{ // check for invalid length of flags and treat 'd' as sampled
return TraceFlags(0);
}
return TraceFlags(TraceFlags::kIsSampled);
}
private:
static SpanContext ExtractImpl(const context::propagation::TextMapCarrier &carrier)
{
nostd::string_view trace_id_hex;
nostd::string_view span_id_hex;
nostd::string_view trace_flags_hex;
// first let's try a single-header variant
auto singleB3Header = carrier.Get(kB3CombinedHeader);
if (!singleB3Header.empty())
{
std::array<nostd::string_view, 3> fields{};
// https://github.com/openzipkin/b3-propagation/blob/master/RATIONALE.md
if (detail::SplitString(singleB3Header, '-', fields.data(), 3) < 2)
{
return SpanContext::GetInvalid();
}
trace_id_hex = fields[0];
span_id_hex = fields[1];
trace_flags_hex = fields[2];
}
else
{
trace_id_hex = carrier.Get(kB3TraceIdHeader);
span_id_hex = carrier.Get(kB3SpanIdHeader);
trace_flags_hex = carrier.Get(kB3SampledHeader);
}
if (!detail::IsValidHex(trace_id_hex) || !detail::IsValidHex(span_id_hex))
{
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);
}
};
// The B3Propagator class provides interface that enables extracting and injecting context into
// single header of HTTP Request.
class B3Propagator : public B3PropagatorExtractor
{
public:
// Sets the context for a HTTP header carrier with self defined rules.
void Inject(context::propagation::TextMapCarrier &carrier,
const context::Context &context) noexcept override
{
SpanContext span_context = trace::GetSpan(context)->GetContext();
if (!span_context.IsValid())
{
return;
}
char trace_identity[kTraceIdHexStrLength + kSpanIdHexStrLength + 3];
static_assert(sizeof(trace_identity) == 51, "b3 trace identity buffer size mismatch");
span_context.trace_id().ToLowerBase16(nostd::span<char, 2 * TraceId::kSize>{
&trace_identity[0], static_cast<std::size_t>(kTraceIdHexStrLength)});
trace_identity[kTraceIdHexStrLength] = '-';
span_context.span_id().ToLowerBase16(nostd::span<char, 2 * SpanId::kSize>{
&trace_identity[kTraceIdHexStrLength + 1], static_cast<std::size_t>(kSpanIdHexStrLength)});
trace_identity[kTraceIdHexStrLength + kSpanIdHexStrLength + 1] = '-';
trace_identity[kTraceIdHexStrLength + kSpanIdHexStrLength + 2] =
span_context.trace_flags().IsSampled() ? '1' : '0';
carrier.Set(kB3CombinedHeader, nostd::string_view(trace_identity, sizeof(trace_identity)));
}
bool Fields(nostd::function_ref<bool(nostd::string_view)> callback) const noexcept override
{
return callback(kB3CombinedHeader);
}
};
class B3PropagatorMultiHeader : public B3PropagatorExtractor
{
public:
void Inject(context::propagation::TextMapCarrier &carrier,
const context::Context &context) noexcept override
{
SpanContext span_context = GetSpan(context)->GetContext();
if (!span_context.IsValid())
{
return;
}
char trace_id[32];
TraceId(span_context.trace_id()).ToLowerBase16(trace_id);
char span_id[16];
SpanId(span_context.span_id()).ToLowerBase16(span_id);
char trace_flags[2];
TraceFlags(span_context.trace_flags()).ToLowerBase16(trace_flags);
carrier.Set(kB3TraceIdHeader, nostd::string_view(trace_id, sizeof(trace_id)));
carrier.Set(kB3SpanIdHeader, nostd::string_view(span_id, sizeof(span_id)));
carrier.Set(kB3SampledHeader, nostd::string_view(trace_flags + 1, 1));
}
bool Fields(nostd::function_ref<bool(nostd::string_view)> callback) const noexcept override
{
return callback(kB3TraceIdHeader) && callback(kB3SpanIdHeader) && callback(kB3SampledHeader);
}
};
} // namespace propagation
} // namespace trace
OPENTELEMETRY_END_NAMESPACE
|
