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5bcac4eaac
Otherwise when PAC server is down, we log, and each log entry is a new HTTP request (from logtail) and a new GetProxyForURL call, which again logs, non-stop. This is also nicer to the WinHTTP service. Then also hook up link change notifications to the cache to reset it if there's a chance the network might work sooner.
90 lines
2.2 KiB
Go
90 lines
2.2 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package tshttpproxy contains Tailscale additions to httpproxy not available
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// in golang.org/x/net/http/httpproxy. Notably, it aims to support Windows better.
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package tshttpproxy
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import (
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"net/http"
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"net/url"
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"os"
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"sync"
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"time"
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)
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// InvalidateCache invalidates the package-level cache for ProxyFromEnvironment.
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//
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// It's intended to be called on network link/routing table changes.
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func InvalidateCache() {
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mu.Lock()
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defer mu.Unlock()
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noProxyUntil = time.Time{}
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}
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var (
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mu sync.Mutex
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noProxyUntil time.Time // if non-zero, time at which ProxyFromEnvironment should check again
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)
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func setNoProxyUntil(d time.Duration) {
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mu.Lock()
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defer mu.Unlock()
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noProxyUntil = time.Now().Add(d)
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}
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// sysProxyFromEnv, if non-nil, specifies a platform-specific ProxyFromEnvironment
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// func to use if http.ProxyFromEnvironment doesn't return a proxy.
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// For example, WPAD PAC files on Windows.
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var sysProxyFromEnv func(*http.Request) (*url.URL, error)
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func ProxyFromEnvironment(req *http.Request) (*url.URL, error) {
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mu.Lock()
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noProxyTime := noProxyUntil
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mu.Unlock()
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if time.Now().Before(noProxyTime) {
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return nil, nil
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}
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u, err := http.ProxyFromEnvironment(req)
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if u != nil && err == nil {
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return u, nil
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}
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if sysProxyFromEnv != nil {
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u, err := sysProxyFromEnv(req)
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if u != nil && err == nil {
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return u, nil
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}
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}
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return nil, err
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}
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var sysAuthHeader func(*url.URL) (string, error)
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// GetAuthHeader returns the Authorization header value to send to proxy u.
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func GetAuthHeader(u *url.URL) (string, error) {
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if fake := os.Getenv("TS_DEBUG_FAKE_PROXY_AUTH"); fake != "" {
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return fake, nil
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}
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if sysAuthHeader != nil {
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return sysAuthHeader(u)
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}
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return "", nil
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}
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var condSetTransportGetProxyConnectHeader func(*http.Transport)
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// SetTarnsportGetProxyConnectHeader sets the provided Transport's
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// GetProxyConnectHeader field, if the current build of Go supports
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// it.
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//
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// See https://github.com/golang/go/issues/41048.
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func SetTransportGetProxyConnectHeader(tr *http.Transport) {
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if f := condSetTransportGetProxyConnectHeader; f != nil {
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f(tr)
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}
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}
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