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fwd.go
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fwd.go
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// package forwarder implements http handler that forwards requests to remote server
// and serves back the response
// websocket proxying support based on https://github.com/yhat/wsutil
package forward
import (
"io"
"net/http"
"net/url"
"os"
"strconv"
"strings"
"time"
"crypto/tls"
"net"
"net/http/httputil"
"reflect"
log "github.com/sirupsen/logrus"
"github.com/vulcand/oxy/utils"
)
// ReqRewriter can alter request headers and body
type ReqRewriter interface {
Rewrite(r *http.Request)
}
type optSetter func(f *Forwarder) error
// PassHostHeader specifies if a client's Host header field should
// be delegated
func PassHostHeader(b bool) optSetter {
return func(f *Forwarder) error {
f.httpForwarder.passHost = b
return nil
}
}
// RoundTripper sets a new http.RoundTripper
// Forwarder will use http.DefaultTransport as a default round tripper
func RoundTripper(r http.RoundTripper) optSetter {
return func(f *Forwarder) error {
f.httpForwarder.roundTripper = r
return nil
}
}
// Rewriter defines a request rewriter for the HTTP forwarder
func Rewriter(r ReqRewriter) optSetter {
return func(f *Forwarder) error {
f.httpForwarder.rewriter = r
return nil
}
}
// PassHostHeader specifies if a client's Host header field should
// be delegated
func WebsocketTLSClientConfig(tcc *tls.Config) optSetter {
return func(f *Forwarder) error {
f.httpForwarder.tlsClientConfig = tcc
return nil
}
}
// ErrorHandler is a functional argument that sets error handler of the server
func ErrorHandler(h utils.ErrorHandler) optSetter {
return func(f *Forwarder) error {
f.errHandler = h
return nil
}
}
// Logger specifies the logger to use.
// Forwarder will default to oxyutils.NullLogger if no logger has been specified
func Stream(stream bool) optSetter {
return func(f *Forwarder) error {
f.stream = stream
return nil
}
}
func StateListener(stateListener UrlForwardingStateListener) optSetter {
return func(f *Forwarder) error {
f.stateListener = stateListener
return nil
}
}
func StreamingFlushInterval(flushInterval time.Duration) optSetter {
return func(f *Forwarder) error {
f.httpForwarder.flushInterval = flushInterval
return nil
}
}
// Forwarder wraps two traffic forwarding implementations: HTTP and websockets.
// It decides based on the specified request which implementation to use
type Forwarder struct {
*httpForwarder
*handlerContext
stateListener UrlForwardingStateListener
stream bool
}
// handlerContext defines a handler context for error reporting and logging
type handlerContext struct {
errHandler utils.ErrorHandler
}
// httpForwarder is a handler that can reverse proxy
// HTTP traffic
type httpForwarder struct {
roundTripper http.RoundTripper
rewriter ReqRewriter
passHost bool
flushInterval time.Duration
tlsClientConfig *tls.Config
}
const (
StateConnected = iota
StateDisconnected
)
type UrlForwardingStateListener func(*url.URL, int)
// New creates an instance of Forwarder based on the provided list of configuration options
func New(setters ...optSetter) (*Forwarder, error) {
f := &Forwarder{
httpForwarder: &httpForwarder{flushInterval: time.Duration(100) * time.Millisecond},
handlerContext: &handlerContext{},
}
for _, s := range setters {
if err := s(f); err != nil {
return nil, err
}
}
if f.httpForwarder.rewriter == nil {
h, err := os.Hostname()
if err != nil {
h = "localhost"
}
f.httpForwarder.rewriter = &HeaderRewriter{TrustForwardHeader: true, Hostname: h}
}
if f.httpForwarder.roundTripper == nil {
f.httpForwarder.roundTripper = http.DefaultTransport
}
if f.errHandler == nil {
f.errHandler = utils.DefaultHandler
}
return f, nil
}
// ServeHTTP decides which forwarder to use based on the specified
// request and delegates to the proper implementation
func (f *Forwarder) ServeHTTP(w http.ResponseWriter, req *http.Request) {
if log.GetLevel() >= log.DebugLevel {
logEntry := log.WithField("Request", utils.DumpHttpRequest(req))
logEntry.Debug("vulcand/oxy/forward: begin ServeHttp on request")
defer logEntry.Debug("vulcand/oxy/forward: competed ServeHttp on request")
}
if f.stateListener != nil {
f.stateListener(req.URL, StateConnected)
defer f.stateListener(req.URL, StateDisconnected)
}
if IsWebsocketRequest(req) {
f.httpForwarder.serveWebSocket(w, req, f.handlerContext)
} else if f.stream {
f.httpForwarder.serveStreamingHTTP(w, req, f.handlerContext)
} else {
f.httpForwarder.serveBufferedHTTP(w, req, f.handlerContext)
}
}
// serveHTTP forwards HTTP traffic using the configured transport
func (f *httpForwarder) serveBufferedHTTP(w http.ResponseWriter, req *http.Request, ctx *handlerContext) {
if log.GetLevel() >= log.DebugLevel {
logEntry := log.WithField("Request", utils.DumpHttpRequest(req))
logEntry.Debug("vulcand/oxy/forward/httpbuffer: begin ServeHttp on request")
defer logEntry.Debug("vulcand/oxy/forward/httpbuffer: competed ServeHttp on request")
}
start := time.Now().UTC()
response, err := f.roundTripper.RoundTrip(f.copyRequest(req, req.URL))
if err != nil {
log.Errorf("vulcand/oxy/forward/httpbuffer: Error forwarding to %v, err: %v", req.URL, err)
ctx.errHandler.ServeHTTP(w, req, err)
return
}
if req.TLS != nil {
log.Infof("vulcand/oxy/forward/httpbuffer: Round trip: %v, code: %v, duration: %v tls:version: %x, tls:resume:%t, tls:csuite:%x, tls:server:%v",
req.URL, response.StatusCode, time.Now().UTC().Sub(start),
req.TLS.Version,
req.TLS.DidResume,
req.TLS.CipherSuite,
req.TLS.ServerName)
} else {
log.Infof("vulcand/oxy/forward/httpbuffer: Round trip: %v, code: %v, duration: %v",
req.URL, response.StatusCode, time.Now().UTC().Sub(start))
}
// Connection: references headers that should be treated as hop by hop
if c := response.Header.Get("Connection"); c != "" {
for _, f := range strings.Split(c, ",") {
if f = strings.TrimSpace(f); f != "" {
response.Header.Del(f)
}
}
}
utils.RemoveHeaders(response.Header, HopHeaders...)
utils.CopyHeaders(w.Header(), response.Header)
w.WriteHeader(response.StatusCode)
written, err := io.Copy(w, response.Body)
defer response.Body.Close()
if err != nil {
log.Errorf("vulcand/oxy/forward/httpbuffer: Error copying upstream response Body: %v", err)
ctx.errHandler.ServeHTTP(w, req, err)
return
}
if written != 0 {
w.Header().Set(ContentLength, strconv.FormatInt(written, 10))
}
}
// copyRequest makes a copy of the specified request to be sent using the configured
// transport
func (f *httpForwarder) copyRequest(req *http.Request, u *url.URL) *http.Request {
outReq := new(http.Request)
*outReq = *req // includes shallow copies of maps, but we handle this below
outReq.URL = utils.CopyURL(req.URL)
outReq.URL.Scheme = u.Scheme
outReq.URL.Host = u.Host
outReq.URL.Opaque = req.RequestURI
// raw query is already included in RequestURI, so ignore it to avoid dupes
outReq.URL.RawQuery = ""
// Do not pass client Host header unless optsetter PassHostHeader is set.
if !f.passHost {
outReq.Host = u.Host
}
outReq.Proto = "HTTP/1.1"
outReq.ProtoMajor = 1
outReq.ProtoMinor = 1
// Overwrite close flag so we can keep persistent connection for the backend servers
outReq.Close = false
outReq.Header = make(http.Header)
utils.CopyHeaders(outReq.Header, req.Header)
if f.rewriter != nil {
f.rewriter.Rewrite(outReq)
}
return outReq
}
// serveHTTP forwards websocket traffic
func (f *httpForwarder) serveWebSocket(w http.ResponseWriter, req *http.Request, ctx *handlerContext) {
if log.GetLevel() >= log.DebugLevel {
logEntry := log.WithField("Request", utils.DumpHttpRequest(req))
logEntry.Debug("vulcand/oxy/forward/websocket: begin ServeHttp on request")
defer logEntry.Debug("vulcand/oxy/forward/websocket: competed ServeHttp on request")
}
outReq := f.copyWebSocketRequest(req)
host := outReq.URL.Host
// if host does not specify a port, use the default http port
if !strings.Contains(host, ":") {
if outReq.URL.Scheme == "wss" {
host = host + ":443"
} else {
host = host + ":80"
}
}
var targetConn net.Conn
var err error
if outReq.URL.Scheme == "wss" && f.tlsClientConfig != nil {
log.Debugf("vulcand/oxy/forward/websocket: Dialing secure (tls) tcp connection to host %s with TLS Client Config %v", host, f.tlsClientConfig)
targetConn, err = tls.Dial("tcp", host, f.tlsClientConfig)
} else {
log.Debugf("vulcand/oxy/forward/websocket: Dialing insecure (non-tls) tcp connection to host %s", host)
targetConn, err = net.Dial("tcp", host)
}
if err != nil {
log.Errorf("vulcand/oxy/forward/websocket: Error dialing `%v`: %v", host, err)
ctx.errHandler.ServeHTTP(w, req, err)
return
}
hijacker, ok := w.(http.Hijacker)
if !ok {
log.Errorf("vulcand/oxy/forward/websocket: Unable to hijack the connection: does not implement http.Hijacker. ResponseWriter implementation type: %v", reflect.TypeOf(w))
ctx.errHandler.ServeHTTP(w, req, err)
return
}
underlyingConn, _, err := hijacker.Hijack()
if err != nil {
log.Errorf("vulcand/oxy/forward/websocket: Unable to hijack the connection: %v", err)
ctx.errHandler.ServeHTTP(w, req, err)
return
}
// it is now caller's responsibility to Close the underlying connection
defer underlyingConn.Close()
defer targetConn.Close()
log.Infof("vulcand/oxy/forward/websocket: Writing outgoing Websocket request to target connection: %+v", outReq)
// write the modified incoming request to the dialed connection
if err = outReq.Write(targetConn); err != nil {
log.Errorf("vulcand/oxy/forward/websocket: Unable to copy request to target: %v", err)
ctx.errHandler.ServeHTTP(w, req, err)
return
}
errc := make(chan error, 2)
replicate := func(dst io.Writer, src io.Reader, dstName string, srcName string) {
_, err := io.Copy(dst, src)
if err != nil {
log.Errorf("vulcand/oxy/forward/websocket: Error when copying from %s to %s using io.Copy: %v", srcName, dstName, err)
} else {
log.Infof("vulcand/oxy/forward/websocket: Copying from %s to %s using io.Copy completed without error.", srcName, dstName)
}
errc <- err
}
go replicate(targetConn, underlyingConn, "backend", "client")
go replicate(underlyingConn, targetConn, "client", "backend")
err = <-errc // One goroutine complete
log.Infof("vulcand/oxy/forward/websocket: first proxying connection closed: %v", err)
err = <-errc // Both goroutines complete
log.Infof("vulcand/oxy/forward/websocket: second proxying connection closed: %v", err)
}
// copyRequest makes a copy of the specified request.
func (f *httpForwarder) copyWebSocketRequest(req *http.Request) (outReq *http.Request) {
outReq = new(http.Request)
*outReq = *req
outReq.URL = utils.CopyURL(req.URL)
//a good working default
outReq.URL.Scheme = req.URL.Scheme
//sometimes backends might be registered as HTTP/HTTPS servers so translate URLs to websocket URLs.
switch req.URL.Scheme {
case "https":
outReq.URL.Scheme = "wss"
case "http":
outReq.URL.Scheme = "ws"
}
outReq.URL.Host = req.URL.Host
outReq.URL.Opaque = req.RequestURI
// Do not pass client Host header unless optsetter PassHostHeader is set.
if !f.passHost {
outReq.Host = req.Host
}
// Overwrite close flag so we can keep persistent connection for the backend servers
outReq.Close = false
outReq.Header = make(http.Header)
utils.CopyHeaders(outReq.Header, req.Header)
if f.rewriter != nil {
f.rewriter.Rewrite(outReq)
}
return outReq
}
// serveHTTP forwards HTTP traffic using the configured transport
func (f *httpForwarder) serveStreamingHTTP(w http.ResponseWriter, inReq *http.Request, ctx *handlerContext) {
if log.GetLevel() >= log.DebugLevel {
logEntry := log.WithField("Request", utils.DumpHttpRequest(inReq))
logEntry.Debug("vulcand/oxy/forward/httpstream: begin ServeHttp on request")
defer logEntry.Debug("vulcand/oxy/forward/httpstream: competed ServeHttp on request")
}
outReq := f.copyRequest(inReq, inReq.URL)
pw := &utils.ProxyWriter{
W: w,
}
start := time.Now().UTC()
reqUrl, err := url.ParseRequestURI(outReq.RequestURI)
if err != nil {
log.Errorf("Error parsing Request URI %v, err: %v", outReq.RequestURI, err)
ctx.errHandler.ServeHTTP(w, outReq, err)
return
}
urlcpy := utils.CopyURL(outReq.URL)
urlcpy.Scheme = outReq.URL.Scheme
urlcpy.Host = outReq.URL.Host
outReq.URL.Path = reqUrl.Path
revproxy := httputil.NewSingleHostReverseProxy(urlcpy)
revproxy.Transport = f.roundTripper
revproxy.FlushInterval = f.flushInterval
revproxy.ServeHTTP(pw, outReq)
if outReq.TLS != nil {
log.Infof("vulcand/oxy/forward/httpstream: Round trip: %v, code: %v, Length: %v, duration: %v tls:version: %x, tls:resume:%t, tls:csuite:%x, tls:server:%v",
outReq.URL, pw.Code, pw.Length, time.Now().UTC().Sub(start),
outReq.TLS.Version,
outReq.TLS.DidResume,
outReq.TLS.CipherSuite,
outReq.TLS.ServerName)
} else {
log.Infof("vulcand/oxy/forward/httpstream: Round trip: %v, code: %v, Length: %v, duration: %v",
outReq.URL, pw.Code, pw.Length, time.Now().UTC().Sub(start))
}
}
// isWebsocketRequest determines if the specified HTTP request is a
// websocket handshake request
func IsWebsocketRequest(req *http.Request) bool {
containsHeader := func(name, value string) bool {
items := strings.Split(req.Header.Get(name), ",")
for _, item := range items {
if value == strings.ToLower(strings.TrimSpace(item)) {
return true
}
}
return false
}
return containsHeader(Connection, "upgrade") && containsHeader(Upgrade, "websocket")
}