cloudflared-mirror/connection/http2.go

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package connection
import (
"bufio"
"context"
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gojson "encoding/json"
"fmt"
"io"
"net"
"net/http"
"runtime/debug"
"strings"
"sync"
"github.com/pkg/errors"
"github.com/rs/zerolog"
"golang.org/x/net/http2"
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"github.com/cloudflare/cloudflared/tracing"
tunnelpogs "github.com/cloudflare/cloudflared/tunnelrpc/pogs"
)
// note: these constants are exported so we can reuse them in the edge-side code
const (
InternalUpgradeHeader = "Cf-Cloudflared-Proxy-Connection-Upgrade"
InternalTCPProxySrcHeader = "Cf-Cloudflared-Proxy-Src"
WebsocketUpgrade = "websocket"
ControlStreamUpgrade = "control-stream"
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ConfigurationUpdate = "update-configuration"
)
var errEdgeConnectionClosed = fmt.Errorf("connection with edge closed")
// HTTP2Connection represents a net.Conn that uses HTTP2 frames to proxy traffic from the edge to cloudflared on the
// origin.
type HTTP2Connection struct {
conn net.Conn
server *http2.Server
orchestrator Orchestrator
connOptions *tunnelpogs.ConnectionOptions
observer *Observer
connIndex uint8
log *zerolog.Logger
activeRequestsWG sync.WaitGroup
controlStreamHandler ControlStreamHandler
stoppedGracefully bool
controlStreamErr error // result of running control stream handler
}
// NewHTTP2Connection returns a new instance of HTTP2Connection.
func NewHTTP2Connection(
conn net.Conn,
orchestrator Orchestrator,
connOptions *tunnelpogs.ConnectionOptions,
observer *Observer,
connIndex uint8,
controlStreamHandler ControlStreamHandler,
log *zerolog.Logger,
) *HTTP2Connection {
return &HTTP2Connection{
conn: conn,
server: &http2.Server{
MaxConcurrentStreams: MaxConcurrentStreams,
},
orchestrator: orchestrator,
connOptions: connOptions,
observer: observer,
connIndex: connIndex,
controlStreamHandler: controlStreamHandler,
log: log,
}
}
// Serve serves an HTTP2 server that the edge can talk to.
func (c *HTTP2Connection) Serve(ctx context.Context) error {
go func() {
<-ctx.Done()
c.close()
}()
c.server.ServeConn(c.conn, &http2.ServeConnOpts{
Context: ctx,
Handler: c,
})
switch {
case c.controlStreamHandler.IsStopped():
return nil
case c.controlStreamErr != nil:
return c.controlStreamErr
default:
c.observer.log.Info().Uint8(LogFieldConnIndex, c.connIndex).Msg("Lost connection with the edge")
return errEdgeConnectionClosed
}
}
func (c *HTTP2Connection) ServeHTTP(w http.ResponseWriter, r *http.Request) {
c.activeRequestsWG.Add(1)
defer c.activeRequestsWG.Done()
connType := determineHTTP2Type(r)
handleMissingRequestParts(connType, r)
respWriter, err := NewHTTP2RespWriter(r, w, connType, c.log)
if err != nil {
c.observer.log.Error().Msg(err.Error())
return
}
originProxy, err := c.orchestrator.GetOriginProxy()
if err != nil {
c.observer.log.Error().Msg(err.Error())
return
}
var requestErr error
switch connType {
case TypeControlStream:
requestErr = c.controlStreamHandler.ServeControlStream(r.Context(), respWriter, c.connOptions, c.orchestrator)
if requestErr != nil {
c.controlStreamErr = requestErr
}
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case TypeConfiguration:
requestErr = c.handleConfigurationUpdate(respWriter, r)
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case TypeWebsocket, TypeHTTP:
stripWebsocketUpgradeHeader(r)
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// Check for tracing on request
tr := tracing.NewTracedHTTPRequest(r, c.connIndex, c.log)
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if err := originProxy.ProxyHTTP(respWriter, tr, connType == TypeWebsocket); err != nil {
requestErr = fmt.Errorf("Failed to proxy HTTP: %w", err)
}
case TypeTCP:
host, err := getRequestHost(r)
if err != nil {
requestErr = fmt.Errorf(`cloudflared received a warp-routing request with an empty host value: %w`, err)
break
}
rws := NewHTTPResponseReadWriterAcker(respWriter, respWriter, r)
requestErr = originProxy.ProxyTCP(r.Context(), rws, &TCPRequest{
Dest: host,
CFRay: FindCfRayHeader(r),
LBProbe: IsLBProbeRequest(r),
CfTraceID: r.Header.Get(tracing.TracerContextName),
ConnIndex: c.connIndex,
})
default:
requestErr = fmt.Errorf("Received unknown connection type: %s", connType)
}
if requestErr != nil {
c.log.Error().Err(requestErr).Msg("failed to serve incoming request")
// WriteErrorResponse will return false if status was already written. we need to abort handler.
if !respWriter.WriteErrorResponse() {
c.log.Debug().Msg("Handler aborted due to failure to write error response after status already sent")
panic(http.ErrAbortHandler)
}
}
}
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// ConfigurationUpdateBody is the representation followed by the edge to send updates to cloudflared.
type ConfigurationUpdateBody struct {
Version int32 `json:"version"`
Config gojson.RawMessage `json:"config"`
}
func (c *HTTP2Connection) handleConfigurationUpdate(respWriter *http2RespWriter, r *http.Request) error {
var configBody ConfigurationUpdateBody
if err := json.NewDecoder(r.Body).Decode(&configBody); err != nil {
return err
}
resp := c.orchestrator.UpdateConfig(configBody.Version, configBody.Config)
bdy, err := json.Marshal(resp)
if err != nil {
return err
}
_, err = respWriter.Write(bdy)
return err
}
func (c *HTTP2Connection) close() {
// Wait for all serve HTTP handlers to return
c.activeRequestsWG.Wait()
c.conn.Close()
}
type http2RespWriter struct {
r io.Reader
w http.ResponseWriter
flusher http.Flusher
shouldFlush bool
statusWritten bool
respHeaders http.Header
hijackedMutex sync.Mutex
hijackedv bool
log *zerolog.Logger
}
func NewHTTP2RespWriter(r *http.Request, w http.ResponseWriter, connType Type, log *zerolog.Logger) (*http2RespWriter, error) {
flusher, isFlusher := w.(http.Flusher)
if !isFlusher {
respWriter := &http2RespWriter{
r: r.Body,
w: w,
log: log,
}
respWriter.WriteErrorResponse()
return nil, fmt.Errorf("%T doesn't implement http.Flusher", w)
}
return &http2RespWriter{
r: r.Body,
w: w,
flusher: flusher,
shouldFlush: connType.shouldFlush(),
respHeaders: make(http.Header),
log: log,
}, nil
}
func (rp *http2RespWriter) AddTrailer(trailerName, trailerValue string) {
if !rp.statusWritten {
rp.log.Warn().Msg("Tried to add Trailer to response before status written. Ignoring...")
return
}
rp.w.Header().Add(http2.TrailerPrefix+trailerName, trailerValue)
}
func (rp *http2RespWriter) WriteRespHeaders(status int, header http.Header) error {
if rp.hijacked() {
rp.log.Warn().Msg("WriteRespHeaders after hijack")
return nil
}
dest := rp.w.Header()
userHeaders := make(http.Header, len(header))
for name, values := range header {
// lowercase headers for simplicity check
h2name := strings.ToLower(name)
if h2name == "content-length" {
// This header has meaning in HTTP/2 and will be used by the edge,
// so it should be sent *also* as an HTTP/2 response header.
dest[name] = values
}
if h2name == tracing.IntCloudflaredTracingHeader {
// Add cf-int-cloudflared-tracing header outside of serialized userHeaders
dest[tracing.CanonicalCloudflaredTracingHeader] = values
continue
}
if !IsControlResponseHeader(h2name) || IsWebsocketClientHeader(h2name) {
// User headers, on the other hand, must all be serialized so that
// HTTP/2 header validation won't be applied to HTTP/1 header values
userHeaders[name] = values
}
}
// Perform user header serialization and set them in the single header
dest.Set(CanonicalResponseUserHeaders, SerializeHeaders(userHeaders))
rp.setResponseMetaHeader(responseMetaHeaderOrigin)
// HTTP2 removes support for 101 Switching Protocols https://tools.ietf.org/html/rfc7540#section-8.1.1
if status == http.StatusSwitchingProtocols {
status = http.StatusOK
}
rp.w.WriteHeader(status)
if shouldFlush(header) {
rp.shouldFlush = true
}
if rp.shouldFlush {
rp.flusher.Flush()
}
rp.statusWritten = true
return nil
}
func (rp *http2RespWriter) Header() http.Header {
return rp.respHeaders
}
func (rp *http2RespWriter) Flush() {
rp.flusher.Flush()
}
func (rp *http2RespWriter) WriteHeader(status int) {
if rp.hijacked() {
rp.log.Warn().Msg("WriteHeader after hijack")
return
}
rp.WriteRespHeaders(status, rp.respHeaders)
}
func (rp *http2RespWriter) hijacked() bool {
rp.hijackedMutex.Lock()
defer rp.hijackedMutex.Unlock()
return rp.hijackedv
}
func (rp *http2RespWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
if !rp.statusWritten {
return nil, nil, fmt.Errorf("status not yet written before attempting to hijack connection")
}
// Make sure to flush anything left in the buffer before hijacking
if rp.shouldFlush {
rp.flusher.Flush()
}
rp.hijackedMutex.Lock()
defer rp.hijackedMutex.Unlock()
if rp.hijackedv {
return nil, nil, http.ErrHijacked
}
rp.hijackedv = true
conn := &localProxyConnection{rp}
// We return the http2RespWriter here because we want to make sure that we flush after every write
// otherwise the HTTP2 write buffer waits a few seconds before sending.
readWriter := bufio.NewReadWriter(
bufio.NewReader(rp),
bufio.NewWriter(rp),
)
return conn, readWriter, nil
}
func (rp *http2RespWriter) WriteErrorResponse() bool {
if rp.statusWritten {
return false
}
rp.setResponseMetaHeader(responseMetaHeaderCfd)
rp.w.WriteHeader(http.StatusBadGateway)
rp.statusWritten = true
return true
}
func (rp *http2RespWriter) setResponseMetaHeader(value string) {
rp.w.Header().Set(CanonicalResponseMetaHeader, value)
}
func (rp *http2RespWriter) Read(p []byte) (n int, err error) {
return rp.r.Read(p)
}
func (rp *http2RespWriter) Write(p []byte) (n int, err error) {
defer func() {
// Implementer of OriginClient should make sure it doesn't write to the connection after Proxy returns
// Register a recover routine just in case.
if r := recover(); r != nil {
rp.log.Debug().Msgf("Recover from http2 response writer panic, error %s", debug.Stack())
}
}()
n, err = rp.w.Write(p)
if err == nil && rp.shouldFlush {
rp.flusher.Flush()
}
return n, err
}
func (rp *http2RespWriter) Close() error {
return nil
}
func determineHTTP2Type(r *http.Request) Type {
switch {
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case isConfigurationUpdate(r):
return TypeConfiguration
case isWebsocketUpgrade(r):
return TypeWebsocket
case IsTCPStream(r):
return TypeTCP
case isControlStreamUpgrade(r):
return TypeControlStream
default:
return TypeHTTP
}
}
func handleMissingRequestParts(connType Type, r *http.Request) {
if connType == TypeHTTP {
// http library has no guarantees that we receive a filled URL. If not, then we fill it, as we reuse the request
// for proxying. We use the same values as we used to in h2mux. For proxying they should not matter since we
// control the dialer on every egress proxied.
if len(r.URL.Scheme) == 0 {
r.URL.Scheme = "http"
}
if len(r.URL.Host) == 0 {
r.URL.Host = "localhost:8080"
}
}
}
func isControlStreamUpgrade(r *http.Request) bool {
return r.Header.Get(InternalUpgradeHeader) == ControlStreamUpgrade
}
func isWebsocketUpgrade(r *http.Request) bool {
return r.Header.Get(InternalUpgradeHeader) == WebsocketUpgrade
}
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func isConfigurationUpdate(r *http.Request) bool {
return r.Header.Get(InternalUpgradeHeader) == ConfigurationUpdate
}
// IsTCPStream discerns if the connection request needs a tcp stream proxy.
func IsTCPStream(r *http.Request) bool {
return r.Header.Get(InternalTCPProxySrcHeader) != ""
}
func stripWebsocketUpgradeHeader(r *http.Request) {
r.Header.Del(InternalUpgradeHeader)
}
// getRequestHost returns the host of the http.Request.
func getRequestHost(r *http.Request) (string, error) {
if r.Host != "" {
return r.Host, nil
}
if r.URL != nil {
return r.URL.Host, nil
}
return "", errors.New("host not set in incoming request")
}