frostfs-s3-gw/pkg/handlers/forwarder.go

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/*
* MinIO Cloud Storage, (C) 2018-2019 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package handlers
import (
"context"
"net"
"net/http"
"net/http/httputil"
"net/url"
"strings"
"time"
)
const defaultFlushInterval = time.Duration(100) * time.Millisecond
// Forwarder forwards all incoming HTTP requests to configured transport.
type Forwarder struct {
RoundTripper http.RoundTripper
PassHost bool
Logger func(error)
// internal variables
rewriter *headerRewriter
}
// NewForwarder creates an instance of Forwarder based on the provided list of configuration options
func NewForwarder(f *Forwarder) *Forwarder {
f.rewriter = &headerRewriter{}
if f.RoundTripper == nil {
f.RoundTripper = http.DefaultTransport
}
return f
}
// ServeHTTP forwards HTTP traffic using the configured transport
func (f *Forwarder) ServeHTTP(w http.ResponseWriter, inReq *http.Request) {
outReq := new(http.Request)
*outReq = *inReq // includes shallow copies of maps, but we handle this in Director
revproxy := httputil.ReverseProxy{
Director: func(req *http.Request) {
f.modifyRequest(req, inReq.URL)
},
Transport: f.RoundTripper,
FlushInterval: defaultFlushInterval,
ErrorHandler: f.customErrHandler,
}
revproxy.ServeHTTP(w, outReq)
}
// customErrHandler is originally implemented to avoid having the following error
// `http: proxy error: context canceled` printed by Golang
func (f *Forwarder) customErrHandler(w http.ResponseWriter, r *http.Request, err error) {
if f.Logger != nil && err != context.Canceled {
f.Logger(err)
}
w.WriteHeader(http.StatusBadGateway)
}
func (f *Forwarder) getURLFromRequest(req *http.Request) *url.URL {
// If the Request was created by Go via a real HTTP request, RequestURI will
// contain the original query string. If the Request was created in code, RequestURI
// will be empty, and we will use the URL object instead
u := req.URL
if req.RequestURI != "" {
parsedURL, err := url.ParseRequestURI(req.RequestURI)
if err == nil {
u = parsedURL
}
}
return u
}
// copyURL provides update safe copy by avoiding shallow copying User field
func copyURL(i *url.URL) *url.URL {
out := *i
if i.User != nil {
u := *i.User
out.User = &u
}
return &out
}
// Modify the request to handle the target URL
func (f *Forwarder) modifyRequest(outReq *http.Request, target *url.URL) {
outReq.URL = copyURL(outReq.URL)
outReq.URL.Scheme = target.Scheme
outReq.URL.Host = target.Host
u := f.getURLFromRequest(outReq)
outReq.URL.Path = u.Path
outReq.URL.RawPath = u.RawPath
outReq.URL.RawQuery = u.RawQuery
outReq.RequestURI = "" // Outgoing request should not have RequestURI
// Do not pass client Host header unless requested.
if !f.PassHost {
outReq.Host = target.Host
}
// TODO: only supports HTTP 1.1 for now.
outReq.Proto = "HTTP/1.1"
outReq.ProtoMajor = 1
outReq.ProtoMinor = 1
f.rewriter.Rewrite(outReq)
// Disable closeNotify when method GET for http pipelining
if outReq.Method == http.MethodGet {
quietReq := outReq.WithContext(context.Background())
*outReq = *quietReq
}
}
// headerRewriter is responsible for removing hop-by-hop headers and setting forwarding headers
type headerRewriter struct{}
// Clean up IP in case if it is ipv6 address and it has {zone} information in it, like
// "[fe80::d806:a55d:eb1b:49cc%vEthernet (vmxnet3 Ethernet Adapter - Virtual Switch)]:64692"
func ipv6fix(clientIP string) string {
return strings.Split(clientIP, "%")[0]
}
func (rw *headerRewriter) Rewrite(req *http.Request) {
if clientIP, _, err := net.SplitHostPort(req.RemoteAddr); err == nil {
clientIP = ipv6fix(clientIP)
if req.Header.Get(xRealIP) == "" {
req.Header.Set(xRealIP, clientIP)
}
}
xfProto := req.Header.Get(xForwardedProto)
if xfProto == "" {
if req.TLS != nil {
req.Header.Set(xForwardedProto, "https")
} else {
req.Header.Set(xForwardedProto, "http")
}
}
if xfPort := req.Header.Get(xForwardedPort); xfPort == "" {
req.Header.Set(xForwardedPort, forwardedPort(req))
}
if xfHost := req.Header.Get(xForwardedHost); xfHost == "" && req.Host != "" {
req.Header.Set(xForwardedHost, req.Host)
}
}
func forwardedPort(req *http.Request) string {
if req == nil {
return ""
}
if _, port, err := net.SplitHostPort(req.Host); err == nil && port != "" {
return port
}
if req.TLS != nil {
return "443"
}
return "80"
}