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e8d2fc7f7f
Updates #11196 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: Id6334c10f52f4cfbda9f03dc8096ab7a6c54a088
220 lines
5.8 KiB
Go
220 lines
5.8 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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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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"context"
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"fmt"
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"log"
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"net"
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"net/http"
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"net/url"
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"os"
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"runtime"
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"strings"
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"sync"
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"time"
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"golang.org/x/net/http/httpproxy"
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"tailscale.com/util/mak"
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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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config *httpproxy.Config // used to create proxyFunc
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proxyFunc func(*url.URL) (*url.URL, error)
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)
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func getProxyFunc() func(*url.URL) (*url.URL, error) {
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// Create config/proxyFunc if it's not created
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mu.Lock()
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defer mu.Unlock()
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if config == nil {
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config = httpproxy.FromEnvironment()
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}
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if proxyFunc == nil {
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proxyFunc = config.ProxyFunc()
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}
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return proxyFunc
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}
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// setNoProxyUntil stops calls to sysProxyEnv (if any) for the provided duration.
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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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var _ = setNoProxyUntil // quiet staticcheck; Windows uses the above, more might later
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// SetSelfProxy configures this package to avoid proxying through any of the
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// provided addresses–e.g. if they refer to proxies being run by this process.
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func SetSelfProxy(addrs ...string) {
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mu.Lock()
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defer mu.Unlock()
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// Ensure we have a valid config
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if config == nil {
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config = httpproxy.FromEnvironment()
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}
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normalizeHostPort := func(s string) string {
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host, portStr, err := net.SplitHostPort(s)
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if err != nil {
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return s
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}
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// Normalize the localhost IP into "localhost", to avoid IPv4/IPv6 confusion.
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if host == "127.0.0.1" || host == "::1" {
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return "localhost:" + portStr
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}
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// On Linux, all 127.0.0.1/8 IPs are also localhost.
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if runtime.GOOS == "linux" && strings.HasPrefix(host, "127.0.0.") {
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return "localhost:" + portStr
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}
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return s
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}
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normHTTP := normalizeHostPort(config.HTTPProxy)
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normHTTPS := normalizeHostPort(config.HTTPSProxy)
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// If any of our proxy variables point to one of the configured
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// addresses, ignore them.
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for _, addr := range addrs {
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normAddr := normalizeHostPort(addr)
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if normHTTP != "" && normHTTP == normAddr {
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log.Printf("tshttpproxy: skipping HTTP_PROXY pointing to self: %q", addr)
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config.HTTPProxy = ""
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normHTTP = ""
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}
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if normHTTPS != "" && normHTTPS == normAddr {
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log.Printf("tshttpproxy: skipping HTTPS_PROXY pointing to self: %q", addr)
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config.HTTPSProxy = ""
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normHTTPS = ""
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}
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}
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// Invalidate to cause it to get re-created
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proxyFunc = nil
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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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// These variables track whether we've printed a log message for a given proxy
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// URL; we only print them once to avoid log spam.
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var (
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logMessageMu sync.Mutex
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logMessagePrinted map[string]bool
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)
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// ProxyFromEnvironment is like the standard library's http.ProxyFromEnvironment
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// but additionally does OS-specific proxy lookups if the environment variables
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// alone don't specify a proxy.
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func ProxyFromEnvironment(req *http.Request) (ret *url.URL, _ error) {
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defer func() {
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if ret == nil {
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return
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}
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ss := ret.String()
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logMessageMu.Lock()
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defer logMessageMu.Unlock()
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if logMessagePrinted[ss] {
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return
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}
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log.Printf("tshttpproxy: using proxy %q for URL: %q", ss, req.URL.String())
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mak.Set(&logMessagePrinted, ss, true)
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}()
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localProxyFunc := getProxyFunc()
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u, err := localProxyFunc(req.URL)
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if u != nil && err == nil {
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return u, nil
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}
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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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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 user := u.User.Username(); user != "" {
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pass, ok := u.User.Password()
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if !ok {
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return "", nil
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}
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req := &http.Request{Header: make(http.Header)}
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req.SetBasicAuth(user, pass)
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return req.Header.Get("Authorization"), 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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const proxyAuthHeader = "Proxy-Authorization"
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// SetTransportGetProxyConnectHeader sets the provided Transport's
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// GetProxyConnectHeader field, and adds logging of the received response.
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func SetTransportGetProxyConnectHeader(tr *http.Transport) {
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tr.GetProxyConnectHeader = func(ctx context.Context, proxyURL *url.URL, target string) (http.Header, error) {
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v, err := GetAuthHeader(proxyURL)
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if err != nil {
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log.Printf("failed to get proxy Auth header for %v; ignoring: %v", proxyURL, err)
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return nil, nil
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}
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if v == "" {
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return nil, nil
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}
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return http.Header{proxyAuthHeader: []string{v}}, nil
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}
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tr.OnProxyConnectResponse = func(ctx context.Context, proxyURL *url.URL, connectReq *http.Request, res *http.Response) error {
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auth := connectReq.Header.Get(proxyAuthHeader)
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const truncLen = 20
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if len(auth) > truncLen {
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auth = fmt.Sprintf("%s...(%d total bytes)", auth[:truncLen], len(auth))
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}
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log.Printf("tshttpproxy: CONNECT response from %v for target %q (auth %q): %v", proxyURL, connectReq.Host, auth, res.Status)
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return nil
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}
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}
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