traefik/vendor/github.com/vulcand/oxy/forward/fwd.go

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2017-02-07 21:33:23 +00:00
// 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 (
"crypto/tls"
"io"
"net"
"net/http"
"net/url"
"os"
"reflect"
"strconv"
"strings"
"time"
"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.passHost = b
return nil
}
}
// StreamResponse forces streaming body (flushes response directly to client)
func StreamResponse(b bool) optSetter {
return func(f *Forwarder) error {
f.httpForwarder.streamResponse = 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.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
}
}
// WebsocketRewriter defines a request rewriter for the websocket forwarder
func WebsocketRewriter(r ReqRewriter) optSetter {
return func(f *Forwarder) error {
f.websocketForwarder.rewriter = r
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 Logger(l utils.Logger) optSetter {
return func(f *Forwarder) error {
f.log = l
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
*websocketForwarder
*handlerContext
}
// handlerContext defines a handler context for error reporting and logging
type handlerContext struct {
errHandler utils.ErrorHandler
log utils.Logger
}
// httpForwarder is a handler that can reverse proxy
// HTTP traffic
type httpForwarder struct {
roundTripper http.RoundTripper
rewriter ReqRewriter
passHost bool
streamResponse bool
}
// websocketForwarder is a handler that can reverse proxy
// websocket traffic
type websocketForwarder struct {
rewriter ReqRewriter
TLSClientConfig *tls.Config
}
// New creates an instance of Forwarder based on the provided list of configuration options
func New(setters ...optSetter) (*Forwarder, error) {
f := &Forwarder{
httpForwarder: &httpForwarder{},
websocketForwarder: &websocketForwarder{},
handlerContext: &handlerContext{},
}
for _, s := range setters {
if err := s(f); err != nil {
return nil, err
}
}
if f.httpForwarder.roundTripper == nil {
f.httpForwarder.roundTripper = http.DefaultTransport
}
if f.httpForwarder.rewriter == nil {
h, err := os.Hostname()
if err != nil {
h = "localhost"
}
f.httpForwarder.rewriter = &HeaderRewriter{TrustForwardHeader: true, Hostname: h}
}
if f.log == nil {
f.log = utils.NullLogger
}
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 isWebsocketRequest(req) {
f.websocketForwarder.serveHTTP(w, req, f.handlerContext)
} else {
f.httpForwarder.serveHTTP(w, req, f.handlerContext)
}
}
// serveHTTP forwards HTTP traffic using the configured transport
func (f *httpForwarder) serveHTTP(w http.ResponseWriter, req *http.Request, ctx *handlerContext) {
start := time.Now().UTC()
response, err := f.roundTripper.RoundTrip(f.copyRequest(req, req.URL))
if err != nil {
ctx.log.Errorf("Error forwarding to %v, err: %v", req.URL, err)
ctx.errHandler.ServeHTTP(w, req, err)
return
}
utils.CopyHeaders(w.Header(), response.Header)
// Remove hop-by-hop headers.
utils.RemoveHeaders(w.Header(), HopHeaders...)
w.WriteHeader(response.StatusCode)
stream := f.streamResponse
if !stream {
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contentType, err := utils.GetHeaderMediaType(response.Header, ContentType)
if err == nil {
stream = contentType == "text/event-stream"
}
}
written, err := io.Copy(newResponseFlusher(w, stream), response.Body)
if req.TLS != nil {
ctx.log.Infof("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 {
ctx.log.Infof("Round trip: %v, code: %v, duration: %v",
req.URL, response.StatusCode, time.Now().UTC().Sub(start))
}
defer response.Body.Close()
if err != nil {
ctx.log.Errorf("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 *websocketForwarder) serveHTTP(w http.ResponseWriter, req *http.Request, ctx *handlerContext) {
outReq := f.copyRequest(req, req.URL)
host := outReq.URL.Host
dial := net.Dial
// 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"
}
}
if outReq.URL.Scheme == "wss" {
if f.TLSClientConfig == nil {
f.TLSClientConfig = http.DefaultTransport.(*http.Transport).TLSClientConfig
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}
dial = func(network, address string) (net.Conn, error) {
return tls.Dial("tcp", host, f.TLSClientConfig)
}
}
targetConn, err := dial("tcp", host)
if err != nil {
ctx.log.Errorf("Error dialing `%v`: %v", host, err)
ctx.errHandler.ServeHTTP(w, req, err)
return
}
hijacker, ok := w.(http.Hijacker)
if !ok {
ctx.log.Errorf("Unable to hijack the connection: %v", reflect.TypeOf(w))
ctx.errHandler.ServeHTTP(w, req, nil)
return
}
underlyingConn, _, err := hijacker.Hijack()
if err != nil {
ctx.log.Errorf("Unable to hijack the connection: %v %v", reflect.TypeOf(w), 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()
ctx.log.Infof("Writing outgoing Websocket request to target connection: %+v", outReq)
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// write the modified incoming request to the dialed connection
if err = outReq.Write(targetConn); err != nil {
ctx.log.Errorf("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) {
_, err := io.Copy(dst, src)
errc <- err
}
go replicate(targetConn, underlyingConn)
go replicate(underlyingConn, targetConn)
<-errc
}
// copyRequest makes a copy of the specified request.
func (f *websocketForwarder) copyRequest(req *http.Request, u *url.URL) (outReq *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
//sometimes backends might be registered as HTTP/HTTPS servers so translate URLs to websocket URLs.
switch u.Scheme {
case "https":
outReq.URL.Scheme = "wss"
case "http":
outReq.URL.Scheme = "ws"
}
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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 = ""
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
}
// 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")
}