Use constant value for unix socket so valid host is set in request URL

[jakubbujny]

Description

When unix socket is used, usually it's in form like VAULT_ADDR="unix:///var/run/vault.sock"
Currently library correctly detects usage of unix socket based on unix:// prefix. However later /var/run/vault.sock is used as Host parameter in HTTP requests over unix socket. It's incorrect as golang URL library expects valid URL in such case so it will try to escape slashes and construct URL in form like: http://%2Fvar%2Frun%2Fvault%2Fvault.sock/v1/secret/data/... what will cause error as host is incorrect.

I propose to use instead "fake" host which is still valid URL as http://unix.socket/v1/secret/data is correct from HTTP perspective - later dial function with unix socket will be used anyway (

vault-client-go/client.go

Lines 97 to 104 in b335dfa

	if strings.HasPrefix(configuration.Address, "unix://") {
	// Adjust the dial context for unix domain socket addresses in the
	// internal HTTP transport, if exists.
	if httpTransport, ok := c.client.Transport.(*http.Transport); ok {
	httpTransport.DialContext = func(context.Context, string, string) (net.Conn, error) {
	return net.Dial("unix", strings.TrimPrefix(configuration.Address, "unix://"))
	}
	} else {

) so host part of the URL will be ignored.

How has this been tested?

Ran go test ./... and tested code locally.

[hashicorp-cla]

All committers have signed the CLA.

[averche]

Thanks again for contributing!

[jakubbujny]

thanks for the suggestions @averche ! I committed them :)

[jakubbujny]

@averche is there any chance to release new version of library with that change?