net/url: misleading error message when url has a leading space #29261
Description
What version of Go are you using (go version)?
$ go version go version go1.11.3 darwin/amd64
Does this issue reproduce with the latest release?
Yes
What operating system and processor architecture are you using (go env)?
go env Output
$ go env GOARCH="amd64" GOBIN="" GOCACHE="/Users/stefanb/Library/Caches/go-build" GOEXE="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="darwin" GOOS="darwin" GOPATH="/Users/stefanb/go" GOPROXY="" GORACE="" GOROOT="/usr/local/Cellar/go/1.11.3/libexec" GOTMPDIR="" GOTOOLDIR="/usr/local/Cellar/go/1.11.3/libexec/pkg/tool/darwin_amd64" GCCGO="gccgo" CC="clang" CXX="clang++" 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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/z2/3bdl__bs0xxd3kmf5c1pj0gm0000gn/T/go-build212726590=/tmp/go-build -gno-record-gcc-switches -fno-common"
What did you do?
package main
import (
"net/http"
)
func main() {
_, err := http.Get(" http://example.org")
if err != nil {
panic(err)
}
}https://play.golang.org/p/jkcYSD6ZRcO
What did you expect to see?
Either
- a generic error message of invalid URL or
- a detailed error of invalid URL scheme or
- a detailed error of leading space in URL
What did you see instead?
A misleading detailed error message:
parse http://example.org: first path segment in URL cannot contain colon
In #24246 the proposed solution was to trim the URLs before using them, but from the given error message it is very hard to see what the real problem is.
I propose to either:
- adjust the error message to eg:
parse http://example.org: URL scheme cannot contain spaces
or
- quote the problematic URL in the error message, so that it is more obvious even if the message itself remains misleading:
parse " http://example.org": first path segment in URL cannot contain colon
or
- ideally both adjust the error message + quote the URL:
parse " http://example.org": URL scheme cannot contain spaces
The cannot contain spaces in error message can be changed for cannot contain whitespace or even contains invalid characters, depending how the check is implemented.
Current implementation:
Lines 540 to 562 in b50210f