noproxy.go

// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// HTTP client implementation. See RFC 2616.
//
// This is the low-level Transport implementation of RoundTripper.
// The high-level interface is in client.go.

package proxy

import (
	"os"
	"strings"

	"github.com/gravitational/teleport"
)

// useProxy reports whether requests to addr should use a proxy,
// according to the NO_PROXY or no_proxy environment variable.
// addr is always a canonicalAddr with a host and port.
func useProxy(addr string) bool {
	if len(addr) == 0 {
		return true
	}
	var noProxy string
	for _, env := range []string{teleport.NoProxy, strings.ToLower(teleport.NoProxy)} {
		noProxy = os.Getenv(env)
		if noProxy != "" {
			break
		}
	}

	if noProxy == "" {
		return true
	}
	if noProxy == "*" {
		return false
	}

	addr = strings.ToLower(strings.TrimSpace(addr))
	if hasPort(addr) {
		addr = addr[:strings.LastIndex(addr, ":")]
	}
	for _, p := range strings.Split(noProxy, ",") {
		p = strings.ToLower(strings.TrimSpace(p))
		if len(p) == 0 {
			continue
		}
		if hasPort(p) {
			p = p[:strings.LastIndex(p, ":")]
		}
		if addr == p {
			return false
		}
		if len(p) == 0 {
			// There is no host part, likely the entry is malformed; ignore.
			continue
		}
		if p[0] == '.' && (strings.HasSuffix(addr, p) || addr == p[1:]) {
			// no_proxy ".foo.com" matches "bar.foo.com" or "foo.com"
			return false
		}
		if p[0] != '.' && strings.HasSuffix(addr, p) && addr[len(addr)-len(p)-1] == '.' {
			// no_proxy "foo.com" matches "bar.foo.com"
			return false
		}
	}
	return true
}

// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
// return true if the string includes a port.
func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }