sslobodr | d046be8 | 2019-01-16 10:02:22 -0500 | [diff] [blame] | 1 | // Copyright 2015 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package httpproxy |
| 16 | |
| 17 | import ( |
| 18 | "bytes" |
| 19 | "context" |
| 20 | "fmt" |
| 21 | "io" |
| 22 | "io/ioutil" |
| 23 | "net" |
| 24 | "net/http" |
| 25 | "net/url" |
| 26 | "strings" |
| 27 | "sync/atomic" |
| 28 | "time" |
| 29 | |
| 30 | "github.com/coreos/etcd/etcdserver/api/v2http/httptypes" |
| 31 | "github.com/coreos/pkg/capnslog" |
| 32 | ) |
| 33 | |
| 34 | var ( |
| 35 | plog = capnslog.NewPackageLogger("github.com/coreos/etcd", "proxy/httpproxy") |
| 36 | |
| 37 | // Hop-by-hop headers. These are removed when sent to the backend. |
| 38 | // http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html |
| 39 | // This list of headers borrowed from stdlib httputil.ReverseProxy |
| 40 | singleHopHeaders = []string{ |
| 41 | "Connection", |
| 42 | "Keep-Alive", |
| 43 | "Proxy-Authenticate", |
| 44 | "Proxy-Authorization", |
| 45 | "Te", // canonicalized version of "TE" |
| 46 | "Trailers", |
| 47 | "Transfer-Encoding", |
| 48 | "Upgrade", |
| 49 | } |
| 50 | ) |
| 51 | |
| 52 | func removeSingleHopHeaders(hdrs *http.Header) { |
| 53 | for _, h := range singleHopHeaders { |
| 54 | hdrs.Del(h) |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | type reverseProxy struct { |
| 59 | director *director |
| 60 | transport http.RoundTripper |
| 61 | } |
| 62 | |
| 63 | func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request) { |
| 64 | reportIncomingRequest(clientreq) |
| 65 | proxyreq := new(http.Request) |
| 66 | *proxyreq = *clientreq |
| 67 | startTime := time.Now() |
| 68 | |
| 69 | var ( |
| 70 | proxybody []byte |
| 71 | err error |
| 72 | ) |
| 73 | |
| 74 | if clientreq.Body != nil { |
| 75 | proxybody, err = ioutil.ReadAll(clientreq.Body) |
| 76 | if err != nil { |
| 77 | msg := fmt.Sprintf("failed to read request body: %v", err) |
| 78 | plog.Println(msg) |
| 79 | e := httptypes.NewHTTPError(http.StatusInternalServerError, "httpproxy: "+msg) |
| 80 | if we := e.WriteTo(rw); we != nil { |
| 81 | plog.Debugf("error writing HTTPError (%v) to %s", we, clientreq.RemoteAddr) |
| 82 | } |
| 83 | return |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | // deep-copy the headers, as these will be modified below |
| 88 | proxyreq.Header = make(http.Header) |
| 89 | copyHeader(proxyreq.Header, clientreq.Header) |
| 90 | |
| 91 | normalizeRequest(proxyreq) |
| 92 | removeSingleHopHeaders(&proxyreq.Header) |
| 93 | maybeSetForwardedFor(proxyreq) |
| 94 | |
| 95 | endpoints := p.director.endpoints() |
| 96 | if len(endpoints) == 0 { |
| 97 | msg := "zero endpoints currently available" |
| 98 | reportRequestDropped(clientreq, zeroEndpoints) |
| 99 | |
| 100 | // TODO: limit the rate of the error logging. |
| 101 | plog.Println(msg) |
| 102 | e := httptypes.NewHTTPError(http.StatusServiceUnavailable, "httpproxy: "+msg) |
| 103 | if we := e.WriteTo(rw); we != nil { |
| 104 | plog.Debugf("error writing HTTPError (%v) to %s", we, clientreq.RemoteAddr) |
| 105 | } |
| 106 | return |
| 107 | } |
| 108 | |
| 109 | var requestClosed int32 |
| 110 | completeCh := make(chan bool, 1) |
| 111 | closeNotifier, ok := rw.(http.CloseNotifier) |
| 112 | ctx, cancel := context.WithCancel(context.Background()) |
| 113 | proxyreq = proxyreq.WithContext(ctx) |
| 114 | defer cancel() |
| 115 | if ok { |
| 116 | closeCh := closeNotifier.CloseNotify() |
| 117 | go func() { |
| 118 | select { |
| 119 | case <-closeCh: |
| 120 | atomic.StoreInt32(&requestClosed, 1) |
| 121 | plog.Printf("client %v closed request prematurely", clientreq.RemoteAddr) |
| 122 | cancel() |
| 123 | case <-completeCh: |
| 124 | } |
| 125 | }() |
| 126 | |
| 127 | defer func() { |
| 128 | completeCh <- true |
| 129 | }() |
| 130 | } |
| 131 | |
| 132 | var res *http.Response |
| 133 | |
| 134 | for _, ep := range endpoints { |
| 135 | if proxybody != nil { |
| 136 | proxyreq.Body = ioutil.NopCloser(bytes.NewBuffer(proxybody)) |
| 137 | } |
| 138 | redirectRequest(proxyreq, ep.URL) |
| 139 | |
| 140 | res, err = p.transport.RoundTrip(proxyreq) |
| 141 | if atomic.LoadInt32(&requestClosed) == 1 { |
| 142 | return |
| 143 | } |
| 144 | if err != nil { |
| 145 | reportRequestDropped(clientreq, failedSendingRequest) |
| 146 | plog.Printf("failed to direct request to %s: %v", ep.URL.String(), err) |
| 147 | ep.Failed() |
| 148 | continue |
| 149 | } |
| 150 | |
| 151 | break |
| 152 | } |
| 153 | |
| 154 | if res == nil { |
| 155 | // TODO: limit the rate of the error logging. |
| 156 | msg := fmt.Sprintf("unable to get response from %d endpoint(s)", len(endpoints)) |
| 157 | reportRequestDropped(clientreq, failedGettingResponse) |
| 158 | plog.Println(msg) |
| 159 | e := httptypes.NewHTTPError(http.StatusBadGateway, "httpproxy: "+msg) |
| 160 | if we := e.WriteTo(rw); we != nil { |
| 161 | plog.Debugf("error writing HTTPError (%v) to %s", we, clientreq.RemoteAddr) |
| 162 | } |
| 163 | return |
| 164 | } |
| 165 | |
| 166 | defer res.Body.Close() |
| 167 | reportRequestHandled(clientreq, res, startTime) |
| 168 | removeSingleHopHeaders(&res.Header) |
| 169 | copyHeader(rw.Header(), res.Header) |
| 170 | |
| 171 | rw.WriteHeader(res.StatusCode) |
| 172 | io.Copy(rw, res.Body) |
| 173 | } |
| 174 | |
| 175 | func copyHeader(dst, src http.Header) { |
| 176 | for k, vv := range src { |
| 177 | for _, v := range vv { |
| 178 | dst.Add(k, v) |
| 179 | } |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | func redirectRequest(req *http.Request, loc url.URL) { |
| 184 | req.URL.Scheme = loc.Scheme |
| 185 | req.URL.Host = loc.Host |
| 186 | } |
| 187 | |
| 188 | func normalizeRequest(req *http.Request) { |
| 189 | req.Proto = "HTTP/1.1" |
| 190 | req.ProtoMajor = 1 |
| 191 | req.ProtoMinor = 1 |
| 192 | req.Close = false |
| 193 | } |
| 194 | |
| 195 | func maybeSetForwardedFor(req *http.Request) { |
| 196 | clientIP, _, err := net.SplitHostPort(req.RemoteAddr) |
| 197 | if err != nil { |
| 198 | return |
| 199 | } |
| 200 | |
| 201 | // If we aren't the first proxy retain prior |
| 202 | // X-Forwarded-For information as a comma+space |
| 203 | // separated list and fold multiple headers into one. |
| 204 | if prior, ok := req.Header["X-Forwarded-For"]; ok { |
| 205 | clientIP = strings.Join(prior, ", ") + ", " + clientIP |
| 206 | } |
| 207 | req.Header.Set("X-Forwarded-For", clientIP) |
| 208 | } |