forked from opentracing/opentracing-go
/
utils.go
62 lines (56 loc) · 1.8 KB
/
utils.go
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
package opentracing
import (
"net/http"
"net/url"
"strings"
)
const (
// ContextIDHTTPHeaderPrefix precedes the opentracing-related ContextID HTTP
// headers.
ContextIDHTTPHeaderPrefix = "Open-Tracing-Context-Id-"
// TagsHTTPHeaderPrefix precedes the opentracing-related trace-tags HTTP
// headers.
TagsHTTPHeaderPrefix = "Open-Tracing-Trace-Tags-"
)
// AddTraceContextToHeader encodes TraceContext `ctx` to `h` as a series of
// HTTP headers. Values are URL-escaped.
func AddTraceContextToHeader(
ctx TraceContext,
h http.Header,
encoder TraceContextEncoder,
) {
contextIDMap, tagsMap := encoder.TraceContextToText(ctx)
for headerSuffix, val := range contextIDMap {
h.Add(ContextIDHTTPHeaderPrefix+headerSuffix, url.QueryEscape(val))
}
for headerSuffix, val := range tagsMap {
h.Add(TagsHTTPHeaderPrefix+headerSuffix, url.QueryEscape(val))
}
}
// TraceContextFromHeader decodes a TraceContext from `h`, expecting that
// header values are URL-escpaed.
func TraceContextFromHeader(
h http.Header,
decoder TraceContextDecoder,
) (TraceContext, error) {
contextIDMap := make(map[string]string)
tagsMap := make(map[string]string)
for key, val := range h {
if strings.HasPrefix(key, ContextIDHTTPHeaderPrefix) {
// We don't know what to do with anything beyond slice item v[0]:
unescaped, err := url.QueryUnescape(val[0])
if err != nil {
return nil, err
}
contextIDMap[strings.TrimPrefix(key, ContextIDHTTPHeaderPrefix)] = unescaped
} else if strings.HasPrefix(key, TagsHTTPHeaderPrefix) {
// We don't know what to do with anything beyond slice item v[0]:
unescaped, err := url.QueryUnescape(val[0])
if err != nil {
return nil, err
}
tagsMap[strings.TrimPrefix(key, TagsHTTPHeaderPrefix)] = unescaped
}
}
return decoder.TraceContextFromText(contextIDMap, tagsMap)
}