/
meek.go
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/
meek.go
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/*
* Copyright (c) 2016, Psiphon Inc.
* All rights reserved.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package server
import (
"bytes"
"crypto/tls"
"encoding/base64"
"encoding/json"
"errors"
"io"
"net"
"net/http"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/Psiphon-Inc/crypto/nacl/box"
"github.com/Psiphon-Inc/goarista/monotime"
"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common"
)
// MeekServer is based on meek-server.go from Tor and Psiphon:
//
// https://gitweb.torproject.org/pluggable-transports/meek.git/blob/HEAD:/meek-client/meek-client.go
// CC0 1.0 Universal
//
// https://bitbucket.org/psiphon/psiphon-circumvention-system/src/default/go/meek-client/meek-client.go
const (
// Protocol version 1 clients can handle arbitrary length response bodies. Older clients
// report no version number and expect at most 64K response bodies.
MEEK_PROTOCOL_VERSION_1 = 1
// Protocol version 2 clients initiate a session by sending a encrypted and obfuscated meek
// cookie with their initial HTTP request. Connection information is contained within the
// encrypted cookie payload. The server inspects the cookie and establishes a new session and
// returns a new random session ID back to client via Set-Cookie header. The client uses this
// session ID on all subsequent requests for the remainder of the session.
MEEK_PROTOCOL_VERSION_2 = 2
MEEK_MAX_PAYLOAD_LENGTH = 0x10000
MEEK_TURN_AROUND_TIMEOUT = 20 * time.Millisecond
MEEK_EXTENDED_TURN_AROUND_TIMEOUT = 100 * time.Millisecond
MEEK_MAX_SESSION_STALENESS = 45 * time.Second
MEEK_HTTP_CLIENT_IO_TIMEOUT = 45 * time.Second
MEEK_MIN_SESSION_ID_LENGTH = 8
MEEK_MAX_SESSION_ID_LENGTH = 20
)
// MeekServer implements the meek protocol, which tunnels TCP traffic (in the case of Psiphon,
// Obfusated SSH traffic) over HTTP. Meek may be fronted (through a CDN) or direct and may be
// HTTP or HTTPS.
//
// Upstream traffic arrives in HTTP request bodies and downstream traffic is sent in response
// bodies. The sequence of traffic for a given flow is associated using a session ID that's
// set as a HTTP cookie for the client to submit with each request.
//
// MeekServer hooks into TunnelServer via the net.Conn interface by transforming the
// HTTP payload traffic for a given session into net.Conn conforming Read()s and Write()s via
// the meekConn struct.
type MeekServer struct {
support *SupportServices
listener net.Listener
tlsConfig *tls.Config
clientHandler func(clientConn net.Conn)
openConns *common.Conns
stopBroadcast <-chan struct{}
sessionsLock sync.RWMutex
sessions map[string]*meekSession
}
// NewMeekServer initializes a new meek server.
func NewMeekServer(
support *SupportServices,
listener net.Listener,
useTLS bool,
clientHandler func(clientConn net.Conn),
stopBroadcast <-chan struct{}) (*MeekServer, error) {
meekServer := &MeekServer{
support: support,
listener: listener,
clientHandler: clientHandler,
openConns: new(common.Conns),
stopBroadcast: stopBroadcast,
sessions: make(map[string]*meekSession),
}
if useTLS {
tlsConfig, err := makeMeekTLSConfig(support)
if err != nil {
return nil, common.ContextError(err)
}
meekServer.tlsConfig = tlsConfig
}
return meekServer, nil
}
// Run runs the meek server; this function blocks while serving HTTP or
// HTTPS connections on the specified listener. This function also runs
// a goroutine which cleans up expired meek client sessions.
//
// To stop the meek server, both Close() the listener and set the stopBroadcast
// signal specified in NewMeekServer.
func (server *MeekServer) Run() error {
defer server.listener.Close()
defer server.openConns.CloseAll()
// Expire sessions
reaperWaitGroup := new(sync.WaitGroup)
reaperWaitGroup.Add(1)
go func() {
defer reaperWaitGroup.Done()
ticker := time.NewTicker(MEEK_MAX_SESSION_STALENESS / 2)
defer ticker.Stop()
for {
select {
case <-ticker.C:
server.closeExpireSessions()
case <-server.stopBroadcast:
return
}
}
}()
// Serve HTTP or HTTPS
// Notes:
// - WriteTimeout may include time awaiting request, as per:
// https://blog.cloudflare.com/the-complete-guide-to-golang-net-http-timeouts
// - Legacy meek-server wrapped each client HTTP connection with an explict idle
// timeout net.Conn and didn't use http.Server timeouts. We could do the same
// here (use ActivityMonitoredConn) but the stock http.Server timeouts should
// now be sufficient.
httpServer := &http.Server{
ReadTimeout: MEEK_HTTP_CLIENT_IO_TIMEOUT,
WriteTimeout: MEEK_HTTP_CLIENT_IO_TIMEOUT,
Handler: server,
ConnState: server.httpConnStateCallback,
// Disable auto HTTP/2 (https://golang.org/doc/go1.6)
TLSNextProto: make(map[string]func(*http.Server, *tls.Conn, http.Handler)),
}
// Note: Serve() will be interrupted by listener.Close() call
var err error
if server.tlsConfig != nil {
httpServer.TLSConfig = server.tlsConfig
httpsServer := HTTPSServer{Server: *httpServer}
err = httpsServer.ServeTLS(server.listener)
} else {
err = httpServer.Serve(server.listener)
}
// Can't check for the exact error that Close() will cause in Accept(),
// (see: https://code.google.com/p/go/issues/detail?id=4373). So using an
// explicit stop signal to stop gracefully.
select {
case <-server.stopBroadcast:
err = nil
default:
}
reaperWaitGroup.Wait()
return err
}
// ServeHTTP handles meek client HTTP requests, where the request body
// contains upstream traffic and the response will contain downstream
// traffic.
func (server *MeekServer) ServeHTTP(responseWriter http.ResponseWriter, request *http.Request) {
// Note: no longer requiring that the request method is POST
// Check for the expected meek/session ID cookie.
// Also check for prohibited HTTP headers.
var meekCookie *http.Cookie
for _, c := range request.Cookies() {
meekCookie = c
break
}
if meekCookie == nil || len(meekCookie.Value) == 0 {
log.WithContext().Warning("missing meek cookie")
server.terminateConnection(responseWriter, request)
return
}
if len(server.support.Config.MeekProhibitedHeaders) > 0 {
for _, header := range server.support.Config.MeekProhibitedHeaders {
value := request.Header.Get(header)
if header != "" {
log.WithContextFields(LogFields{
"header": header,
"value": value,
}).Warning("prohibited meek header")
server.terminateConnection(responseWriter, request)
return
}
}
}
// Lookup or create a new session for given meek cookie/session ID.
sessionID, session, err := server.getSession(request, meekCookie)
if err != nil {
log.WithContextFields(LogFields{"error": err}).Warning("session lookup failed")
server.terminateConnection(responseWriter, request)
return
}
// pumpReads causes a TunnelServer/SSH goroutine blocking on a Read to
// read the request body as upstream traffic.
// TODO: run pumpReads and pumpWrites concurrently?
err = session.clientConn.pumpReads(request.Body)
if err != nil {
if err != io.EOF {
log.WithContextFields(LogFields{"error": err}).Warning("pump reads failed")
}
server.terminateConnection(responseWriter, request)
server.closeSession(sessionID)
return
}
// Set cookie before writing the response.
if session.meekProtocolVersion >= MEEK_PROTOCOL_VERSION_2 && session.sessionIDSent == false {
// Replace the meek cookie with the session ID.
// SetCookie for the the session ID cookie is only set once, to reduce overhead. This
// session ID value replaces the original meek cookie value.
http.SetCookie(responseWriter, &http.Cookie{Name: meekCookie.Name, Value: sessionID})
session.sessionIDSent = true
}
// pumpWrites causes a TunnelServer/SSH goroutine blocking on a Write to
// write its downstream traffic through to the response body.
err = session.clientConn.pumpWrites(responseWriter)
if err != nil {
if err != io.EOF {
log.WithContextFields(LogFields{"error": err}).Warning("pump writes failed")
}
server.terminateConnection(responseWriter, request)
server.closeSession(sessionID)
return
}
}
// getSession returns the meek client session corresponding the
// meek cookie/session ID. If no session is found, the cookie is
// treated as a meek cookie for a new session and its payload is
// extracted and used to establish a new session.
func (server *MeekServer) getSession(
request *http.Request, meekCookie *http.Cookie) (string, *meekSession, error) {
// Check for an existing session
server.sessionsLock.RLock()
existingSessionID := meekCookie.Value
session, ok := server.sessions[existingSessionID]
server.sessionsLock.RUnlock()
if ok {
session.touch()
return existingSessionID, session, nil
}
// TODO: can multiple http client connections using same session cookie
// cause race conditions on session struct?
// The session is new (or expired). Treat the cookie value as a new meek
// cookie, extract the payload, and create a new session.
payloadJSON, err := getMeekCookiePayload(server.support, meekCookie.Value)
if err != nil {
return "", nil, common.ContextError(err)
}
// Note: this meek server ignores all but Version MeekProtocolVersion;
// the other values are legacy or currently unused.
var clientSessionData struct {
MeekProtocolVersion int `json:"v"`
PsiphonClientSessionId string `json:"s"`
PsiphonServerAddress string `json:"p"`
}
err = json.Unmarshal(payloadJSON, &clientSessionData)
if err != nil {
return "", nil, common.ContextError(err)
}
// Determine the client remote address, which is used for geolocation
// and stats. When an intermediate proxy or CDN is in use, we may be
// able to determine the original client address by inspecting HTTP
// headers such as X-Forwarded-For.
clientIP := strings.Split(request.RemoteAddr, ":")[0]
if len(server.support.Config.MeekProxyForwardedForHeaders) > 0 {
for _, header := range server.support.Config.MeekProxyForwardedForHeaders {
value := request.Header.Get(header)
if len(value) > 0 {
// Some headers, such as X-Forwarded-For, are a comma-separated
// list of IPs (each proxy in a chain). The first IP should be
// the client IP.
proxyClientIP := strings.Split(value, ",")[0]
if net.ParseIP(proxyClientIP) != nil &&
server.support.GeoIPService.Lookup(proxyClientIP).Country != GEOIP_UNKNOWN_VALUE {
clientIP = proxyClientIP
break
}
}
}
}
// Create a new meek conn that will relay the payload
// between meek request/responses and the tunnel server client
// handler. The client IP is also used to initialize the
// meek conn with a useful value to return when the tunnel
// server calls conn.RemoteAddr() to get the client's IP address.
// Assumes clientIP is a valid IP address; the port value is a stub
// and is expected to be ignored.
clientConn := newMeekConn(
&net.TCPAddr{
IP: net.ParseIP(clientIP),
Port: 0,
},
clientSessionData.MeekProtocolVersion)
session = &meekSession{
clientConn: clientConn,
meekProtocolVersion: clientSessionData.MeekProtocolVersion,
sessionIDSent: false,
}
session.touch()
// Note: MEEK_PROTOCOL_VERSION_1 doesn't support changing the
// meek cookie to a session ID; v1 clients always send the
// original meek cookie value with each request. The issue with
// v1 is that clients which wake after a device sleep will attempt
// to resume a meek session and the server can't differentiate
// between resuming a session and creating a new session. This
// causes the v1 client connection to hang/timeout.
sessionID := meekCookie.Value
if clientSessionData.MeekProtocolVersion >= MEEK_PROTOCOL_VERSION_2 {
sessionID, err = makeMeekSessionID()
if err != nil {
return "", nil, common.ContextError(err)
}
}
server.sessionsLock.Lock()
server.sessions[sessionID] = session
server.sessionsLock.Unlock()
// Note: from the tunnel server's perspective, this client connection
// will close when closeSessionHelper calls Close() on the meekConn.
server.clientHandler(session.clientConn)
return sessionID, session, nil
}
func (server *MeekServer) closeSessionHelper(
sessionID string, session *meekSession) {
// TODO: close the persistent HTTP client connection, if one exists
session.clientConn.Close()
// Note: assumes caller holds lock on sessionsLock
delete(server.sessions, sessionID)
}
func (server *MeekServer) closeSession(sessionID string) {
server.sessionsLock.Lock()
session, ok := server.sessions[sessionID]
if ok {
server.closeSessionHelper(sessionID, session)
}
server.sessionsLock.Unlock()
}
func (server *MeekServer) closeExpireSessions() {
server.sessionsLock.Lock()
for sessionID, session := range server.sessions {
if session.expired() {
server.closeSessionHelper(sessionID, session)
}
}
server.sessionsLock.Unlock()
}
// httpConnStateCallback tracks open persistent HTTP/HTTPS connections to the
// meek server.
func (server *MeekServer) httpConnStateCallback(conn net.Conn, connState http.ConnState) {
switch connState {
case http.StateNew:
server.openConns.Add(conn)
case http.StateHijacked, http.StateClosed:
server.openConns.Remove(conn)
}
}
// terminateConnection sends a 404 response to a client and also closes
// a persisitent connection.
func (server *MeekServer) terminateConnection(
responseWriter http.ResponseWriter, request *http.Request) {
http.NotFound(responseWriter, request)
hijack, ok := responseWriter.(http.Hijacker)
if !ok {
return
}
conn, buffer, err := hijack.Hijack()
if err != nil {
return
}
buffer.Flush()
conn.Close()
}
type meekSession struct {
// Note: 64-bit ints used with atomic operations are at placed
// at the start of struct to ensure 64-bit alignment.
// (https://golang.org/pkg/sync/atomic/#pkg-note-BUG)
lastActivity int64
clientConn *meekConn
meekProtocolVersion int
sessionIDSent bool
}
func (session *meekSession) touch() {
atomic.StoreInt64(&session.lastActivity, int64(monotime.Now()))
}
func (session *meekSession) expired() bool {
lastActivity := monotime.Time(atomic.LoadInt64(&session.lastActivity))
return monotime.Since(lastActivity) > MEEK_MAX_SESSION_STALENESS
}
// makeMeekTLSConfig creates a TLS config for a meek HTTPS listener.
// Currently, this config is optimized for fronted meek where the nature
// of the connection is non-circumvention; it's optimized for performance
// assuming the peer is an uncensored CDN.
func makeMeekTLSConfig(support *SupportServices) (*tls.Config, error) {
certificate, privateKey, err := GenerateWebServerCertificate(
support.Config.MeekCertificateCommonName)
if err != nil {
return nil, common.ContextError(err)
}
tlsCertificate, err := tls.X509KeyPair(
[]byte(certificate), []byte(privateKey))
if err != nil {
return nil, common.ContextError(err)
}
return &tls.Config{
Certificates: []tls.Certificate{tlsCertificate},
NextProtos: []string{"http/1.1"},
MinVersion: tls.VersionTLS10,
// This is a reordering of the supported CipherSuites in golang 1.6. Non-ephemeral key
// CipherSuites greatly reduce server load, and we try to select these since the meek
// protocol is providing obfuscation, not privacy/integrity (this is provided by the
// tunneled SSH), so we don't benefit from the perfect forward secrecy property provided
// by ephemeral key CipherSuites.
// https://github.com/golang/go/blob/1cb3044c9fcd88e1557eca1bf35845a4108bc1db/src/crypto/tls/cipher_suites.go#L75
CipherSuites: []uint16{
tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
tls.TLS_RSA_WITH_RC4_128_SHA,
tls.TLS_RSA_WITH_AES_128_CBC_SHA,
tls.TLS_RSA_WITH_AES_256_CBC_SHA,
tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA,
tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
},
PreferServerCipherSuites: true,
}, nil
}
// getMeekCookiePayload extracts the payload from a meek cookie. The cookie
// paylod is base64 encoded, obfuscated, and NaCl encrypted.
func getMeekCookiePayload(support *SupportServices, cookieValue string) ([]byte, error) {
decodedValue, err := base64.StdEncoding.DecodeString(cookieValue)
if err != nil {
return nil, common.ContextError(err)
}
// The data consists of an obfuscated seed message prepended
// to the obfuscated, encrypted payload. The server obfuscator
// will read the seed message, leaving the remaining encrypted
// data in the reader.
reader := bytes.NewReader(decodedValue[:])
obfuscator, err := common.NewServerObfuscator(
reader,
&common.ObfuscatorConfig{Keyword: support.Config.MeekObfuscatedKey})
if err != nil {
return nil, common.ContextError(err)
}
offset, err := reader.Seek(0, 1)
if err != nil {
return nil, common.ContextError(err)
}
encryptedPayload := decodedValue[offset:]
obfuscator.ObfuscateClientToServer(encryptedPayload)
var nonce [24]byte
var privateKey, ephemeralPublicKey [32]byte
decodedPrivateKey, err := base64.StdEncoding.DecodeString(
support.Config.MeekCookieEncryptionPrivateKey)
if err != nil {
return nil, common.ContextError(err)
}
copy(privateKey[:], decodedPrivateKey)
if len(encryptedPayload) < 32 {
return nil, common.ContextError(errors.New("unexpected encrypted payload size"))
}
copy(ephemeralPublicKey[0:32], encryptedPayload[0:32])
payload, ok := box.Open(nil, encryptedPayload[32:], &nonce, &ephemeralPublicKey, &privateKey)
if !ok {
return nil, common.ContextError(errors.New("open box failed"))
}
return payload, nil
}
// makeMeekSessionID creates a new session ID. The variable size is intended to
// frustrate traffic analysis of both plaintext and TLS meek traffic.
func makeMeekSessionID() (string, error) {
size := MEEK_MIN_SESSION_ID_LENGTH
n, err := common.MakeSecureRandomInt(MEEK_MAX_SESSION_ID_LENGTH - MEEK_MIN_SESSION_ID_LENGTH)
if err != nil {
return "", common.ContextError(err)
}
size += n
sessionID, err := common.MakeRandomStringBase64(size)
if err != nil {
return "", common.ContextError(err)
}
return sessionID, nil
}
// meekConn implements the net.Conn interface and is to be used as a client
// connection by the tunnel server (being passed to sshServer.handleClient).
// meekConn bridges net/http request/response payload readers and writers
// and goroutines calling Read()s and Write()s.
type meekConn struct {
remoteAddr net.Addr
protocolVersion int
closeBroadcast chan struct{}
closed int32
readLock sync.Mutex
emptyReadBuffer chan *bytes.Buffer
partialReadBuffer chan *bytes.Buffer
fullReadBuffer chan *bytes.Buffer
writeLock sync.Mutex
nextWriteBuffer chan []byte
writeResult chan error
}
func newMeekConn(remoteAddr net.Addr, protocolVersion int) *meekConn {
conn := &meekConn{
remoteAddr: remoteAddr,
protocolVersion: protocolVersion,
closeBroadcast: make(chan struct{}),
closed: 0,
emptyReadBuffer: make(chan *bytes.Buffer, 1),
partialReadBuffer: make(chan *bytes.Buffer, 1),
fullReadBuffer: make(chan *bytes.Buffer, 1),
nextWriteBuffer: make(chan []byte, 1),
writeResult: make(chan error, 1),
}
// Read() calls and pumpReads() are synchronized by exchanging control
// of a single readBuffer. This is the same scheme used in and described
// in psiphon.MeekConn.
conn.emptyReadBuffer <- new(bytes.Buffer)
return conn
}
// pumpReads causes goroutines blocking on meekConn.Read() to read
// from the specified reader. This function blocks until the reader
// is fully consumed or the meekConn is closed. A read buffer allows
// up to MEEK_MAX_PAYLOAD_LENGTH bytes to be read and buffered without
// a Read() immediately consuming the bytes, but there's still a
// possibility of a stall if no Read() calls are made after this
// read buffer is full.
// Note: assumes only one concurrent call to pumpReads
func (conn *meekConn) pumpReads(reader io.Reader) error {
for {
var readBuffer *bytes.Buffer
select {
case readBuffer = <-conn.emptyReadBuffer:
case readBuffer = <-conn.partialReadBuffer:
case <-conn.closeBroadcast:
return io.EOF
}
limitReader := io.LimitReader(reader, int64(MEEK_MAX_PAYLOAD_LENGTH-readBuffer.Len()))
n, err := readBuffer.ReadFrom(limitReader)
conn.replaceReadBuffer(readBuffer)
if n == 0 || err != nil {
return err
}
}
}
// Read reads from the meekConn into buffer. Read blocks until
// some data is read or the meekConn closes. Under the hood, it
// waits for pumpReads to submit a reader to read from.
// Note: lock is to conform with net.Conn concurrency semantics
func (conn *meekConn) Read(buffer []byte) (int, error) {
conn.readLock.Lock()
defer conn.readLock.Unlock()
var readBuffer *bytes.Buffer
select {
case readBuffer = <-conn.partialReadBuffer:
case readBuffer = <-conn.fullReadBuffer:
case <-conn.closeBroadcast:
return 0, io.EOF
}
n, err := readBuffer.Read(buffer)
conn.replaceReadBuffer(readBuffer)
return n, err
}
func (conn *meekConn) replaceReadBuffer(readBuffer *bytes.Buffer) {
switch readBuffer.Len() {
case MEEK_MAX_PAYLOAD_LENGTH:
conn.fullReadBuffer <- readBuffer
case 0:
conn.emptyReadBuffer <- readBuffer
default:
conn.partialReadBuffer <- readBuffer
}
}
// pumpWrites causes goroutines blocking on meekConn.Write() to write
// to the specified writer. This function blocks until the meek response
// body limits (size for protocol v1, turn around time for protocol v2+)
// are met, or the meekConn is closed.
// Note: channel scheme assumes only one concurrent call to pumpWrites
func (conn *meekConn) pumpWrites(writer io.Writer) error {
startTime := monotime.Now()
timeout := time.NewTimer(MEEK_TURN_AROUND_TIMEOUT)
defer timeout.Stop()
for {
select {
case buffer := <-conn.nextWriteBuffer:
_, err := writer.Write(buffer)
// Assumes that writeResult won't block.
// Note: always send the err to writeResult,
// as the Write() caller is blocking on this.
conn.writeResult <- err
if err != nil {
return err
}
if conn.protocolVersion < MEEK_PROTOCOL_VERSION_1 {
// Pre-protocol version 1 clients expect at most
// MEEK_MAX_PAYLOAD_LENGTH response bodies
return nil
}
totalElapsedTime := monotime.Since(startTime) / time.Millisecond
if totalElapsedTime >= MEEK_EXTENDED_TURN_AROUND_TIMEOUT {
return nil
}
timeout.Reset(MEEK_TURN_AROUND_TIMEOUT)
case <-timeout.C:
return nil
case <-conn.closeBroadcast:
return io.EOF
}
}
}
// Write writes the buffer to the meekConn. It blocks until the
// entire buffer is written to or the meekConn closes. Under the
// hood, it waits for sufficient pumpWrites calls to consume the
// write buffer.
// Note: lock is to conform with net.Conn concurrency semantics
func (conn *meekConn) Write(buffer []byte) (int, error) {
conn.writeLock.Lock()
defer conn.writeLock.Unlock()
// TODO: may be more efficient to send whole buffer
// and have pumpWrites stash partial buffer when can't
// send it all.
n := 0
for n < len(buffer) {
end := n + MEEK_MAX_PAYLOAD_LENGTH
if end > len(buffer) {
end = len(buffer)
}
// Only write MEEK_MAX_PAYLOAD_LENGTH at a time,
// to ensure compatibility with v1 protocol.
chunk := buffer[n:end]
select {
case conn.nextWriteBuffer <- chunk:
case <-conn.closeBroadcast:
return n, io.EOF
}
// Wait for the buffer to be processed.
select {
case err := <-conn.writeResult:
if err != nil {
return n, err
}
case <-conn.closeBroadcast:
return n, io.EOF
}
n += len(chunk)
}
return n, nil
}
// Close closes the meekConn. This will interrupt any blocked
// Read, Write, pumpReads, and pumpWrites.
func (conn *meekConn) Close() error {
if atomic.CompareAndSwapInt32(&conn.closed, 0, 1) {
close(conn.closeBroadcast)
}
return nil
}
// Stub implementation of net.Conn.LocalAddr
func (conn *meekConn) LocalAddr() net.Addr {
return nil
}
// RemoteAddr returns the remoteAddr specified in newMeekConn. This
// acts as a proxy for the actual remote address, which is either a
// direct HTTP/HTTPS connection remote address, or in the case of
// downstream proxy of CDN fronts, some other value determined via
// HTTP headers.
func (conn *meekConn) RemoteAddr() net.Addr {
return conn.remoteAddr
}
// SetDeadline is not a true implementation of net.Conn.SetDeadline. It
// merely checks that the requested timeout exceeds the MEEK_MAX_SESSION_STALENESS
// period. When it does, and the session is idle, the meekConn Read/Write will
// be interrupted and return io.EOF (not a timeout error) before the deadline.
// In other words, this conn will approximate the desired functionality of
// timing out on idle on or before the requested deadline.
func (conn *meekConn) SetDeadline(t time.Time) error {
// Overhead: nanoseconds (https://blog.cloudflare.com/its-go-time-on-linux/)
if time.Now().Add(MEEK_MAX_SESSION_STALENESS).Before(t) {
return nil
}
return common.ContextError(errors.New("not supported"))
}
// Stub implementation of net.Conn.SetReadDeadline
func (conn *meekConn) SetReadDeadline(t time.Time) error {
return common.ContextError(errors.New("not supported"))
}
// Stub implementation of net.Conn.SetWriteDeadline
func (conn *meekConn) SetWriteDeadline(t time.Time) error {
return common.ContextError(errors.New("not supported"))
}