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cloudflared/connection

connection/http2.go

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1package connection
2
3import (
4 "context"
5 "fmt"
6 "io"
7 "math"
8 "net"
9 "net/http"
10 "strings"
11 "sync"
12
13 "github.com/rs/zerolog"
14 "golang.org/x/net/http2"
15
16 tunnelpogs "github.com/cloudflare/cloudflared/tunnelrpc/pogs"
17)
18
19// note: these constants are exported so we can reuse them in the edge-side code
20const (
21 InternalUpgradeHeader = "Cf-Cloudflared-Proxy-Connection-Upgrade"
22 InternalTCPProxySrcHeader = "Cf-Cloudflared-Proxy-Src"
23 WebsocketUpgrade = "websocket"
24 ControlStreamUpgrade = "control-stream"
25)
26
27var errEdgeConnectionClosed = fmt.Errorf("connection with edge closed")
28
29type http2Connection struct {
30 conn net.Conn
31 server *http2.Server
32 config *Config
33 namedTunnel *NamedTunnelConfig
34 connOptions *tunnelpogs.ConnectionOptions
35 observer *Observer
36 connIndexStr string
37 connIndex uint8
38 // newRPCClientFunc allows us to mock RPCs during testing
39 newRPCClientFunc func(context.Context, io.ReadWriteCloser, *zerolog.Logger) NamedTunnelRPCClient
40
41 activeRequestsWG sync.WaitGroup
42 connectedFuse ConnectedFuse
43 gracefulShutdownC <-chan struct{}
44 stoppedGracefully bool
45 controlStreamErr error // result of running control stream handler
46}
47
48func NewHTTP2Connection(
49 conn net.Conn,
50 config *Config,
51 namedTunnelConfig *NamedTunnelConfig,
52 connOptions *tunnelpogs.ConnectionOptions,
53 observer *Observer,
54 connIndex uint8,
55 connectedFuse ConnectedFuse,
56 gracefulShutdownC <-chan struct{},
57) *http2Connection {
58 return &http2Connection{
59 conn: conn,
60 server: &http2.Server{
61 MaxConcurrentStreams: math.MaxUint32,
62 },
63 config: config,
64 namedTunnel: namedTunnelConfig,
65 connOptions: connOptions,
66 observer: observer,
67 connIndexStr: uint8ToString(connIndex),
68 connIndex: connIndex,
69 newRPCClientFunc: newRegistrationRPCClient,
70 connectedFuse: connectedFuse,
71 gracefulShutdownC: gracefulShutdownC,
72 }
73}
74
75func (c *http2Connection) Serve(ctx context.Context) error {
76 go func() {
77 <-ctx.Done()
78 c.close()
79 }()
80 c.server.ServeConn(c.conn, &http2.ServeConnOpts{
81 Context: ctx,
82 Handler: c,
83 })
84
85 switch {
86 case c.stoppedGracefully:
87 return nil
88 case c.controlStreamErr != nil:
89 return c.controlStreamErr
90 default:
91 c.observer.log.Info().Uint8(LogFieldConnIndex, c.connIndex).Msg("Lost connection with the edge")
92 return errEdgeConnectionClosed
93 }
94}
95
96func (c *http2Connection) ServeHTTP(w http.ResponseWriter, r *http.Request) {
97 c.activeRequestsWG.Add(1)
98 defer c.activeRequestsWG.Done()
99
100 connType := determineHTTP2Type(r)
101 respWriter, err := newHTTP2RespWriter(r, w, connType)
102 if err != nil {
103 c.observer.log.Error().Msg(err.Error())
104 return
105 }
106
107 var proxyErr error
108 switch connType {
109 case TypeControlStream:
110 proxyErr = c.serveControlStream(r.Context(), respWriter)
111 c.controlStreamErr = proxyErr
112 case TypeWebsocket:
113 stripWebsocketUpgradeHeader(r)
114 proxyErr = c.config.OriginProxy.Proxy(respWriter, r, TypeWebsocket)
115 default:
116 proxyErr = c.config.OriginProxy.Proxy(respWriter, r, connType)
117 }
118 if proxyErr != nil {
119 respWriter.WriteErrorResponse()
120 }
121}
122
123func (c *http2Connection) serveControlStream(ctx context.Context, respWriter *http2RespWriter) error {
124 rpcClient := c.newRPCClientFunc(ctx, respWriter, c.observer.log)
125 defer rpcClient.Close()
126
127 if err := rpcClient.RegisterConnection(ctx, c.namedTunnel, c.connOptions, c.connIndex, c.observer); err != nil {
128 return err
129 }
130 c.connectedFuse.Connected()
131
132 // wait for connection termination or start of graceful shutdown
133 select {
134 case <-ctx.Done():
135 break
136 case <-c.gracefulShutdownC:
137 c.stoppedGracefully = true
138 }
139
140 c.observer.sendUnregisteringEvent(c.connIndex)
141 rpcClient.GracefulShutdown(ctx, c.config.GracePeriod)
142 c.observer.log.Info().Uint8(LogFieldConnIndex, c.connIndex).Msg("Unregistered tunnel connection")
143 return nil
144}
145
146func (c *http2Connection) close() {
147 // Wait for all serve HTTP handlers to return
148 c.activeRequestsWG.Wait()
149 c.conn.Close()
150}
151
152type http2RespWriter struct {
153 r io.Reader
154 w http.ResponseWriter
155 flusher http.Flusher
156 shouldFlush bool
157}
158
159func newHTTP2RespWriter(r *http.Request, w http.ResponseWriter, connType Type) (*http2RespWriter, error) {
160 flusher, isFlusher := w.(http.Flusher)
161 if !isFlusher {
162 respWriter := &http2RespWriter{
163 r: r.Body,
164 w: w,
165 }
166 respWriter.WriteErrorResponse()
167 return nil, fmt.Errorf("%T doesn't implement http.Flusher", w)
168 }
169
170 return &http2RespWriter{
171 r: r.Body,
172 w: w,
173 flusher: flusher,
174 shouldFlush: connType.shouldFlush(),
175 }, nil
176}
177
178func (rp *http2RespWriter) WriteRespHeaders(status int, header http.Header) error {
179 dest := rp.w.Header()
180 userHeaders := make(http.Header, len(header))
181 for name, values := range header {
182 // Since these are http2 headers, they're required to be lowercase
183 h2name := strings.ToLower(name)
184 if h2name == "content-length" {
185 // This header has meaning in HTTP/2 and will be used by the edge,
186 // so it should be sent as an HTTP/2 response header.
187 dest[name] = values
188 // Since these are http2 headers, they're required to be lowercase
189 } else if !IsControlHeader(h2name) || IsWebsocketClientHeader(h2name) {
190 // User headers, on the other hand, must all be serialized so that
191 // HTTP/2 header validation won't be applied to HTTP/1 header values
192 userHeaders[name] = values
193 }
194 }
195
196 // Perform user header serialization and set them in the single header
197 dest.Set(CanonicalResponseUserHeaders, SerializeHeaders(userHeaders))
198 rp.setResponseMetaHeader(responseMetaHeaderOrigin)
199 // HTTP2 removes support for 101 Switching Protocols https://tools.ietf.org/html/rfc7540#section-8.1.1
200 if status == http.StatusSwitchingProtocols {
201 status = http.StatusOK
202 }
203 rp.w.WriteHeader(status)
204 if IsServerSentEvent(header) {
205 rp.shouldFlush = true
206 }
207 if rp.shouldFlush {
208 rp.flusher.Flush()
209 }
210 return nil
211}
212
213func (rp *http2RespWriter) WriteErrorResponse() {
214 rp.setResponseMetaHeader(responseMetaHeaderCfd)
215 rp.w.WriteHeader(http.StatusBadGateway)
216}
217
218func (rp *http2RespWriter) setResponseMetaHeader(value string) {
219 rp.w.Header().Set(CanonicalResponseMetaHeader, value)
220}
221
222func (rp *http2RespWriter) Read(p []byte) (n int, err error) {
223 return rp.r.Read(p)
224}
225
226func (rp *http2RespWriter) Write(p []byte) (n int, err error) {
227 defer func() {
228 // Implementer of OriginClient should make sure it doesn't write to the connection after Proxy returns
229 // Register a recover routine just in case.
230 if r := recover(); r != nil {
231 println("Recover from http2 response writer panic, error", r)
232 }
233 }()
234 n, err = rp.w.Write(p)
235 if err == nil && rp.shouldFlush {
236 rp.flusher.Flush()
237 }
238 return n, err
239}
240
241func (rp *http2RespWriter) Close() error {
242 return nil
243}
244
245func determineHTTP2Type(r *http.Request) Type {
246 switch {
247 case isWebsocketUpgrade(r):
248 return TypeWebsocket
249 case IsTCPStream(r):
250 return TypeTCP
251 case isControlStreamUpgrade(r):
252 return TypeControlStream
253 default:
254 return TypeHTTP
255 }
256}
257
258func isControlStreamUpgrade(r *http.Request) bool {
259 return r.Header.Get(InternalUpgradeHeader) == ControlStreamUpgrade
260}
261
262func isWebsocketUpgrade(r *http.Request) bool {
263 return r.Header.Get(InternalUpgradeHeader) == WebsocketUpgrade
264}
265
266// IsTCPStream discerns if the connection request needs a tcp stream proxy.
267func IsTCPStream(r *http.Request) bool {
268 return r.Header.Get(InternalTCPProxySrcHeader) != ""
269}
270
271func stripWebsocketUpgradeHeader(r *http.Request) {
272 r.Header.Del(InternalUpgradeHeader)
273}
274