80 lines
1.8 KiB
Go
80 lines
1.8 KiB
Go
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// Copyright (c) 2021 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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// HTTP proxy code
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package main
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import (
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"context"
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"io"
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"net"
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"net/http"
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"net/http/httputil"
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"strings"
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)
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// httpProxyHandler returns an HTTP proxy http.Handler using the
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// provided backend dialer.
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func httpProxyHandler(dialer func(ctx context.Context, netw, addr string) (net.Conn, error)) http.Handler {
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rp := &httputil.ReverseProxy{
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Director: func(r *http.Request) {}, // no change
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Transport: &http.Transport{
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DialContext: dialer,
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},
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}
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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if r.Method != "CONNECT" {
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backURL := r.RequestURI
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if strings.HasPrefix(backURL, "/") || backURL == "*" {
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http.Error(w, "bogus RequestURI; must be absolute URL or CONNECT", 400)
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return
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}
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rp.ServeHTTP(w, r)
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return
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}
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// CONNECT support:
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dst := r.RequestURI
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c, err := dialer(r.Context(), "tcp", dst)
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if err != nil {
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w.Header().Set("Tailscale-Connect-Error", err.Error())
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http.Error(w, err.Error(), 500)
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return
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}
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defer c.Close()
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cc, ccbuf, err := w.(http.Hijacker).Hijack()
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if err != nil {
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http.Error(w, err.Error(), 500)
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return
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}
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defer cc.Close()
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io.WriteString(cc, "HTTP/1.1 200 OK\r\n\r\n")
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var clientSrc io.Reader = ccbuf
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if ccbuf.Reader.Buffered() == 0 {
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// In the common case (with no
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// buffered data), read directly from
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// the underlying client connection to
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// save some memory, letting the
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// bufio.Reader/Writer get GC'ed.
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clientSrc = cc
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}
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errc := make(chan error, 1)
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go func() {
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_, err := io.Copy(cc, c)
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errc <- err
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}()
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go func() {
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_, err := io.Copy(c, clientSrc)
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errc <- err
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}()
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<-errc
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})
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}
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