Description
What version of Go are you using (go version)?
$ go version go version go1.12.7 linux/amd64
Does this issue reproduce with the latest release?
Yes
What operating system and processor architecture are you using (go env)?
Any environment
go env Output
GOARCH="amd64" GOBIN="" GOCACHE="/home/user/.cache/go-build" GOEXE="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOOS="linux" GOPATH="/home/user/go" GOPROXY="" GORACE="" GOROOT="/usr/local/go" GOTMPDIR="" GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64" GCCGO="gccgo" CC="gcc" CXX="g++" CGO_ENABLED="1" GOMOD="" CGO_CFLAGS="-g -O2" CGO_CPPFLAGS="" CGO_CXXFLAGS="-g -O2" CGO_FFLAGS="-g -O2" CGO_LDFLAGS="-g -O2" PKG_CONFIG="pkg-config" GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build606111517=/tmp/go-build -gno-record-gcc-switches"
What did you do?
package main
import (
"fmt"
"html/template"
"net/http"
"net/url"
)
type content struct {
TplEncoded string
ManuallyEncoded template.URL
ShowPaths bool
RawPath string
Path string
}
func main() {
tpl, _ := template.New("test").Parse(`<!doctype html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta charset="utf-8" />
</head>
<body>
{{ if .ShowPaths }}
<p>RawPath = {{ .RawPath }}</p>
<p>Path = {{ .Path }}</p>
{{ else }}
<a href="/link/{{ .TplEncoded }}">Template encoded link</a><br />
<a href="/link/{{ .ManuallyEncoded }}">Manually encoded link</a>
<br />
<p>View this page's source to see the (lower/upper)case difference
in the links</p>
{{ end }}
</body>
</html>`)
// Renders the root with good and bad links.
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
s := "😋" // Unicode emoji.
tpl.Execute(w, content{
// html/template encodes into lowercase characters.
TplEncoded: s,
// url.PathEscape encodes into uppercase characters.
ManuallyEncoded: template.URL(url.PathEscape(s)),
})
})
// This handler produces inconsistent RawPath based on (upper/lower)case encoding in the URI.
http.HandleFunc("/link/", func(w http.ResponseWriter, r *http.Request) {
tpl.Execute(w, content{
ShowPaths: true,
RawPath: r.URL.RawPath,
Path: r.URL.Path,
})
})
fmt.Println("Go to http://127.0.0.1:8080")
http.ListenAndServe(":8080", nil)
}What did you expect to see?
url.PathEscape("😋") => %F0%9F%98%8B
/link/%F0%9F%98%8B (A) and /link/%f0%9f%98%8b (B) (upper and lower case respectively) are equivalent as per RFC 3986. An http.HandlerFunc() handling either of the URLs is expected to show consistent behaviour.
What did you see instead?
An http handler that processes the identical URIs A and B behaves differently. B, which has uppercase characters, produces an empty http.Request.URL.RawPath where as A that has lowercase characters produces an http.Request.URL.RawPath with unescaped characters. This breaks Unicode URL handling in popular HTTP routers like chi and httprouter.
Discovered this inconsistency when using html/template that encodes Unicode strings in <a> to have lowercase characters as opposed to url.PathEscape that produces uppercase characters.