net/http: ProxyFromEnvironment does not support socks5h

[sorsasampo]

What version of Go are you using (go version)?

go version go1.10 linux/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/user/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/user/go"
GORACE=""
GOROOT="/home/user/go1.10"
GOTMPDIR=""
GOTOOLDIR="/home/user/go1.10/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
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-build712629011=/tmp/go-build -gno-record-gcc-switches"

What did you do?

What did you expect to see?

What did you see instead?

go get does not understand socks5h in HTTPS_PROXY, even though it understands socks5.

For example, to test using the tor proxy:

$ HTTPS_PROXY=socks5h://127.0.0.1:9050 go get -v golang.org/x/tools/cmd/goimports
Fetching https://golang.org/x/tools/cmd/goimports?go-get=1
https fetch failed: Get https://golang.org/x/tools/cmd/goimports?go-get=1: proxyconnect tcp: dial tcp: lookup socks5h: No address associated with hostname
package golang.org/x/tools/cmd/goimports: unrecognized import path "golang.org/x/tools/cmd/goimports" (https fetch: Get https://golang.org/x/tools/cmd/goimports?go-get=1: proxyconnect tcp: dial tcp: lookup socks5h: No address associated with hostname)

Other tools that understand HTTPS_PROXY also understand socks5h (resolve hostname through the proxy, not locally). curl and yum, for example.

Related to issue #18508.

[bradfitz]

Seems reasonable. We need to clean up the x/net/socks* packages first, but then somebody can do this.

/cc @mikioh