mirror of
https://github.com/tailscale/tailscale.git
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96 lines
2.7 KiB
Go
96 lines
2.7 KiB
Go
// 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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package controlhttp
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import (
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"bufio"
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"context"
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"encoding/base64"
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"errors"
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"fmt"
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"net"
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"net/http"
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"tailscale.com/control/controlbase"
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"tailscale.com/types/key"
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)
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// AcceptHTTP upgrades the HTTP request given by w and r into a
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// Tailscale control protocol base transport connection.
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//
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// AcceptHTTP always writes an HTTP response to w. The caller must not
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// attempt their own response after calling AcceptHTTP.
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func AcceptHTTP(ctx context.Context, w http.ResponseWriter, r *http.Request, private key.MachinePrivate) (*controlbase.Conn, error) {
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next := r.Header.Get("Upgrade")
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if next == "" {
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http.Error(w, "missing next protocol", http.StatusBadRequest)
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return nil, errors.New("no next protocol in HTTP request")
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}
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if next != upgradeHeaderValue {
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http.Error(w, "unknown next protocol", http.StatusBadRequest)
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return nil, fmt.Errorf("client requested unhandled next protocol %q", next)
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}
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initB64 := r.Header.Get(handshakeHeaderName)
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if initB64 == "" {
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http.Error(w, "missing Tailscale handshake header", http.StatusBadRequest)
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return nil, errors.New("no tailscale handshake header in HTTP request")
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}
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init, err := base64.StdEncoding.DecodeString(initB64)
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if err != nil {
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http.Error(w, "invalid tailscale handshake header", http.StatusBadRequest)
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return nil, fmt.Errorf("decoding base64 handshake header: %v", err)
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}
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hijacker, ok := w.(http.Hijacker)
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if !ok {
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http.Error(w, "make request over HTTP/1", http.StatusBadRequest)
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return nil, errors.New("can't hijack client connection")
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}
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w.Header().Set("Upgrade", upgradeHeaderValue)
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w.Header().Set("Connection", "upgrade")
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w.WriteHeader(http.StatusSwitchingProtocols)
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conn, brw, err := hijacker.Hijack()
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if err != nil {
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return nil, fmt.Errorf("hijacking client connection: %w", err)
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}
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if err := brw.Flush(); err != nil {
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conn.Close()
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return nil, fmt.Errorf("flushing hijacked HTTP buffer: %w", err)
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}
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if brw.Reader.Buffered() > 0 {
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conn = &drainBufConn{conn, brw.Reader}
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}
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nc, err := controlbase.Server(ctx, conn, private, init)
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if err != nil {
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conn.Close()
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return nil, fmt.Errorf("noise handshake failed: %w", err)
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}
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return nc, nil
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}
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// drainBufConn is a net.Conn with an initial bunch of bytes in a
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// bufio.Reader. Read drains the bufio.Reader until empty, then passes
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// through subsequent reads to the Conn directly.
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type drainBufConn struct {
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net.Conn
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r *bufio.Reader
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}
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func (b *drainBufConn) Read(bs []byte) (int, error) {
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if b.r == nil {
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return b.Conn.Read(bs)
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}
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n, err := b.r.Read(bs)
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if b.r.Buffered() == 0 {
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b.r = nil
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}
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return n, err
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}
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