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restic/vendor/golang.org/x/net/http/httpproxy/proxy.go
Alexander Neumann 946c8399e2 Update dependenciess
Exclude minio-go for now (pin to 3.x.y).
2017-12-03 21:22:33 +01:00

240 lines
7.0 KiB
Go

// Copyright 2017 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.
// Package httpproxy provides support for HTTP proxy determination
// based on environment variables, as provided by net/http's
// ProxyFromEnvironment function.
//
// The API is not subject to the Go 1 compatibility promise and may change at
// any time.
package httpproxy
import (
"errors"
"fmt"
"net"
"net/url"
"os"
"strings"
"unicode/utf8"
"golang.org/x/net/idna"
)
// Config holds configuration for HTTP proxy settings. See
// FromEnvironment for details.
type Config struct {
// HTTPProxy represents the value of the HTTP_PROXY or
// http_proxy environment variable. It will be used as the proxy
// URL for HTTP requests and HTTPS requests unless overridden by
// HTTPSProxy or NoProxy.
HTTPProxy string
// HTTPSProxy represents the HTTPS_PROXY or https_proxy
// environment variable. It will be used as the proxy URL for
// HTTPS requests unless overridden by NoProxy.
HTTPSProxy string
// NoProxy represents the NO_PROXY or no_proxy environment
// variable. It specifies URLs that should be excluded from
// proxying as a comma-separated list of domain names or a
// single asterisk (*) to indicate that no proxying should be
// done. A domain name matches that name and all subdomains. A
// domain name with a leading "." matches subdomains only. For
// example "foo.com" matches "foo.com" and "bar.foo.com";
// ".y.com" matches "x.y.com" but not "y.com".
NoProxy string
// CGI holds whether the current process is running
// as a CGI handler (FromEnvironment infers this from the
// presence of a REQUEST_METHOD environment variable).
// When this is set, ProxyForURL will return an error
// when HTTPProxy applies, because a client could be
// setting HTTP_PROXY maliciously. See https://golang.org/s/cgihttpproxy.
CGI bool
}
// FromEnvironment returns a Config instance populated from the
// environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the
// lowercase versions thereof). HTTPS_PROXY takes precedence over
// HTTP_PROXY for https requests.
//
// The environment values may be either a complete URL or a
// "host[:port]", in which case the "http" scheme is assumed. An error
// is returned if the value is a different form.
func FromEnvironment() *Config {
return &Config{
HTTPProxy: getEnvAny("HTTP_PROXY", "http_proxy"),
HTTPSProxy: getEnvAny("HTTPS_PROXY", "https_proxy"),
NoProxy: getEnvAny("NO_PROXY", "no_proxy"),
CGI: os.Getenv("REQUEST_METHOD") != "",
}
}
func getEnvAny(names ...string) string {
for _, n := range names {
if val := os.Getenv(n); val != "" {
return val
}
}
return ""
}
// ProxyFunc returns a function that determines the proxy URL to use for
// a given request URL. Changing the contents of cfg will not affect
// proxy functions created earlier.
//
// A nil URL and nil error are returned if no proxy is defined in the
// environment, or a proxy should not be used for the given request, as
// defined by NO_PROXY.
//
// As a special case, if req.URL.Host is "localhost" (with or without a
// port number), then a nil URL and nil error will be returned.
func (cfg *Config) ProxyFunc() func(reqURL *url.URL) (*url.URL, error) {
// Prevent Config changes from affecting the function calculation.
// TODO Preprocess proxy settings for more efficient evaluation.
cfg1 := *cfg
return cfg1.proxyForURL
}
func (cfg *Config) proxyForURL(reqURL *url.URL) (*url.URL, error) {
var proxy string
if reqURL.Scheme == "https" {
proxy = cfg.HTTPSProxy
}
if proxy == "" {
proxy = cfg.HTTPProxy
if proxy != "" && cfg.CGI {
return nil, errors.New("refusing to use HTTP_PROXY value in CGI environment; see golang.org/s/cgihttpproxy")
}
}
if proxy == "" {
return nil, nil
}
if !cfg.useProxy(canonicalAddr(reqURL)) {
return nil, nil
}
proxyURL, err := url.Parse(proxy)
if err != nil ||
(proxyURL.Scheme != "http" &&
proxyURL.Scheme != "https" &&
proxyURL.Scheme != "socks5") {
// proxy was bogus. Try prepending "http://" to it and
// see if that parses correctly. If not, we fall
// through and complain about the original one.
if proxyURL, err := url.Parse("http://" + proxy); err == nil {
return proxyURL, nil
}
}
if err != nil {
return nil, fmt.Errorf("invalid proxy address %q: %v", proxy, err)
}
return proxyURL, nil
}
// 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 (cfg *Config) useProxy(addr string) bool {
if len(addr) == 0 {
return true
}
host, _, err := net.SplitHostPort(addr)
if err != nil {
return false
}
if host == "localhost" {
return false
}
if ip := net.ParseIP(host); ip != nil {
if ip.IsLoopback() {
return false
}
}
noProxy := cfg.NoProxy
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
}
var portMap = map[string]string{
"http": "80",
"https": "443",
"socks5": "1080",
}
// canonicalAddr returns url.Host but always with a ":port" suffix
func canonicalAddr(url *url.URL) string {
addr := url.Hostname()
if v, err := idnaASCII(addr); err == nil {
addr = v
}
port := url.Port()
if port == "" {
port = portMap[url.Scheme]
}
return net.JoinHostPort(addr, port)
}
// 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, "]") }
func idnaASCII(v string) (string, error) {
// TODO: Consider removing this check after verifying performance is okay.
// Right now punycode verification, length checks, context checks, and the
// permissible character tests are all omitted. It also prevents the ToASCII
// call from salvaging an invalid IDN, when possible. As a result it may be
// possible to have two IDNs that appear identical to the user where the
// ASCII-only version causes an error downstream whereas the non-ASCII
// version does not.
// Note that for correct ASCII IDNs ToASCII will only do considerably more
// work, but it will not cause an allocation.
if isASCII(v) {
return v, nil
}
return idna.Lookup.ToASCII(v)
}
func isASCII(s string) bool {
for i := 0; i < len(s); i++ {
if s[i] >= utf8.RuneSelf {
return false
}
}
return true
}