mirror of
https://github.com/gravitational/teleport.git
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rosstimothy
fa3bb9ac59
The `http.Client.Transport` created in `newWebClient` wraps a chain of `http.RoundTripper` over an underlying `http.Transport`. Since we cannot guarantee that each `http.RoundTipper` has a `CloseIdleConnections` method the usage of `defer clt.CloseIdleConnections()` does not guarantee that the http connections created during Find/Ping/etc are closed. To prevent leaking connections implementations of `http.RoundTripper` have added a `CloseIdleConnections` method added that forwards the request on to the wrapped interface. The `otelhttp.Transport` does not implement this method either so care has been taken to wrap it in a `http.RoundTripper` which will call the root transport in `enforceCloseIdleConnections`. An upstream issue has been filed with otelhttp: https://github.com/open-telemetry/opentelemetry-go-contrib/issues/3543 to get the method added to their `Transport` implementation. This wasn't noticed prior to upgrading to go1.20 becuase prior to [this](https://github.com/golang/go/commit/4e7e7ae1406c70d9cc0809ec11105a55a60a0b70) commit the `ReadHeaderTimeout` set on the Proxy web api http.Server would cause the connection to appear idle and get terminated by the server. `TestWebClientClosesIdleConnections` was added to capture the leak in connections as reported in #22757 and prevent any regressions.
120 lines
3.6 KiB
Go
120 lines
3.6 KiB
Go
/*
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Copyright 2022 Gravitational, Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package proxy
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import (
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"net/http"
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"net/url"
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"strings"
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"github.com/gravitational/trace"
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"golang.org/x/net/http/httpproxy"
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)
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// GetProxyURL gets the HTTP proxy address to use for a given address, if any.
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func GetProxyURL(dialAddr string) *url.URL {
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addrURL, err := parse(dialAddr)
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if err != nil || addrURL == nil {
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return nil
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}
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proxyFunc := httpproxy.FromEnvironment().ProxyFunc()
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if addrURL.Scheme != "" {
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proxyURL, err := proxyFunc(addrURL)
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if err != nil {
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return nil
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}
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return proxyURL
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}
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for _, scheme := range []string{"https", "http"} {
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addrURL.Scheme = scheme
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proxyURL, err := proxyFunc(addrURL)
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if err == nil && proxyURL != nil {
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return proxyURL
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}
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}
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return nil
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}
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// parse parses an absolute URL. Unlike url.Parse, absolute URLs without a scheme are allowed.
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func parse(addr string) (*url.URL, error) {
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if addr == "" {
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return nil, nil
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}
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addrURL, err := url.Parse(addr)
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if err == nil && addrURL.Host != "" {
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return addrURL, nil
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}
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// url.Parse won't correctly parse an absolute URL without a scheme, so try again with a scheme.
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addrURL, err2 := url.Parse("http://" + addr)
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if err2 != nil {
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return nil, trace.NewAggregate(err, err2)
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}
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addrURL.Scheme = ""
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return addrURL, nil
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}
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// HTTPRoundTripper is a wrapper for http.Transport that
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// - adds extra HTTP headers to all requests, and
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// - downgrades requests to plain HTTP when proxy is at localhost and the wrapped http.Transport has TLSClientConfig.InsecureSkipVerify set to true.
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type HTTPRoundTripper struct {
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*http.Transport
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// extraHeaders is a map of extra HTTP headers to be included in requests.
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extraHeaders map[string]string
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// isProxyHTTPLocalhost indicates that the HTTP_PROXY is at "http://localhost"
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isProxyHTTPLocalhost bool
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}
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// NewHTTPRoundTripper creates a new initialized HTTP roundtripper.
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func NewHTTPRoundTripper(transport *http.Transport, extraHeaders map[string]string) *HTTPRoundTripper {
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proxyConfig := httpproxy.FromEnvironment()
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return &HTTPRoundTripper{
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Transport: transport,
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extraHeaders: extraHeaders,
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isProxyHTTPLocalhost: strings.HasPrefix(proxyConfig.HTTPProxy, "http://localhost"),
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}
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}
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// CloseIdleConnections forwards closing of idle connections on to the wrapped
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// transport. This is required to ensure that the underlying [http.Transport] has
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// its idle connections closed per the [http.Client] docs:
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//
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// > If the Client's Transport does not have a CloseIdleConnections method
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// > then this method does nothing.
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func (rt *HTTPRoundTripper) CloseIdleConnections() {
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rt.Transport.CloseIdleConnections()
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}
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// RoundTrip executes a single HTTP transaction. Part of the RoundTripper interface.
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func (rt *HTTPRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
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// Add extra HTTP headers.
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for header, v := range rt.extraHeaders {
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req.Header.Add(header, v)
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}
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// Use plain HTTP if proxying via http://localhost in insecure mode.
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tlsConfig := rt.Transport.TLSClientConfig
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if rt.isProxyHTTPLocalhost && tlsConfig != nil && tlsConfig.InsecureSkipVerify {
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req.URL.Scheme = "http"
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}
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return rt.Transport.RoundTrip(req)
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}
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