khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 1 | // Copyright 2017 The Prometheus Authors |
| 2 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 3 | // you may not use this file except in compliance with the License. |
| 4 | // You may obtain a copy of the License at |
| 5 | // |
| 6 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 7 | // |
| 8 | // Unless required by applicable law or agreed to in writing, software |
| 9 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 10 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 11 | // See the License for the specific language governing permissions and |
| 12 | // limitations under the License. |
| 13 | |
| 14 | package promhttp |
| 15 | |
| 16 | import ( |
| 17 | "bufio" |
| 18 | "io" |
| 19 | "net" |
| 20 | "net/http" |
| 21 | ) |
| 22 | |
| 23 | const ( |
| 24 | closeNotifier = 1 << iota |
| 25 | flusher |
| 26 | hijacker |
| 27 | readerFrom |
| 28 | pusher |
| 29 | ) |
| 30 | |
| 31 | type delegator interface { |
| 32 | http.ResponseWriter |
| 33 | |
| 34 | Status() int |
| 35 | Written() int64 |
| 36 | } |
| 37 | |
| 38 | type responseWriterDelegator struct { |
| 39 | http.ResponseWriter |
| 40 | |
| 41 | status int |
| 42 | written int64 |
| 43 | wroteHeader bool |
| 44 | observeWriteHeader func(int) |
| 45 | } |
| 46 | |
| 47 | func (r *responseWriterDelegator) Status() int { |
| 48 | return r.status |
| 49 | } |
| 50 | |
| 51 | func (r *responseWriterDelegator) Written() int64 { |
| 52 | return r.written |
| 53 | } |
| 54 | |
| 55 | func (r *responseWriterDelegator) WriteHeader(code int) { |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 56 | if r.observeWriteHeader != nil && !r.wroteHeader { |
| 57 | // Only call observeWriteHeader for the 1st time. It's a bug if |
| 58 | // WriteHeader is called more than once, but we want to protect |
| 59 | // against it here. Note that we still delegate the WriteHeader |
| 60 | // to the original ResponseWriter to not mask the bug from it. |
| 61 | r.observeWriteHeader(code) |
| 62 | } |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 63 | r.status = code |
| 64 | r.wroteHeader = true |
| 65 | r.ResponseWriter.WriteHeader(code) |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 66 | } |
| 67 | |
| 68 | func (r *responseWriterDelegator) Write(b []byte) (int, error) { |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 69 | // If applicable, call WriteHeader here so that observeWriteHeader is |
| 70 | // handled appropriately. |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 71 | if !r.wroteHeader { |
| 72 | r.WriteHeader(http.StatusOK) |
| 73 | } |
| 74 | n, err := r.ResponseWriter.Write(b) |
| 75 | r.written += int64(n) |
| 76 | return n, err |
| 77 | } |
| 78 | |
| 79 | type closeNotifierDelegator struct{ *responseWriterDelegator } |
| 80 | type flusherDelegator struct{ *responseWriterDelegator } |
| 81 | type hijackerDelegator struct{ *responseWriterDelegator } |
| 82 | type readerFromDelegator struct{ *responseWriterDelegator } |
| 83 | type pusherDelegator struct{ *responseWriterDelegator } |
| 84 | |
| 85 | func (d closeNotifierDelegator) CloseNotify() <-chan bool { |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 86 | //nolint:staticcheck // Ignore SA1019. http.CloseNotifier is deprecated but we keep it here to not break existing users. |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 87 | return d.ResponseWriter.(http.CloseNotifier).CloseNotify() |
| 88 | } |
| 89 | func (d flusherDelegator) Flush() { |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 90 | // If applicable, call WriteHeader here so that observeWriteHeader is |
| 91 | // handled appropriately. |
| 92 | if !d.wroteHeader { |
| 93 | d.WriteHeader(http.StatusOK) |
| 94 | } |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 95 | d.ResponseWriter.(http.Flusher).Flush() |
| 96 | } |
| 97 | func (d hijackerDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) { |
| 98 | return d.ResponseWriter.(http.Hijacker).Hijack() |
| 99 | } |
| 100 | func (d readerFromDelegator) ReadFrom(re io.Reader) (int64, error) { |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 101 | // If applicable, call WriteHeader here so that observeWriteHeader is |
| 102 | // handled appropriately. |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 103 | if !d.wroteHeader { |
| 104 | d.WriteHeader(http.StatusOK) |
| 105 | } |
| 106 | n, err := d.ResponseWriter.(io.ReaderFrom).ReadFrom(re) |
| 107 | d.written += n |
| 108 | return n, err |
| 109 | } |
| 110 | func (d pusherDelegator) Push(target string, opts *http.PushOptions) error { |
| 111 | return d.ResponseWriter.(http.Pusher).Push(target, opts) |
| 112 | } |
| 113 | |
| 114 | var pickDelegator = make([]func(*responseWriterDelegator) delegator, 32) |
| 115 | |
| 116 | func init() { |
| 117 | // TODO(beorn7): Code generation would help here. |
| 118 | pickDelegator[0] = func(d *responseWriterDelegator) delegator { // 0 |
| 119 | return d |
| 120 | } |
| 121 | pickDelegator[closeNotifier] = func(d *responseWriterDelegator) delegator { // 1 |
| 122 | return closeNotifierDelegator{d} |
| 123 | } |
| 124 | pickDelegator[flusher] = func(d *responseWriterDelegator) delegator { // 2 |
| 125 | return flusherDelegator{d} |
| 126 | } |
| 127 | pickDelegator[flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 3 |
| 128 | return struct { |
| 129 | *responseWriterDelegator |
| 130 | http.Flusher |
| 131 | http.CloseNotifier |
| 132 | }{d, flusherDelegator{d}, closeNotifierDelegator{d}} |
| 133 | } |
| 134 | pickDelegator[hijacker] = func(d *responseWriterDelegator) delegator { // 4 |
| 135 | return hijackerDelegator{d} |
| 136 | } |
| 137 | pickDelegator[hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 5 |
| 138 | return struct { |
| 139 | *responseWriterDelegator |
| 140 | http.Hijacker |
| 141 | http.CloseNotifier |
| 142 | }{d, hijackerDelegator{d}, closeNotifierDelegator{d}} |
| 143 | } |
| 144 | pickDelegator[hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 6 |
| 145 | return struct { |
| 146 | *responseWriterDelegator |
| 147 | http.Hijacker |
| 148 | http.Flusher |
| 149 | }{d, hijackerDelegator{d}, flusherDelegator{d}} |
| 150 | } |
| 151 | pickDelegator[hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 7 |
| 152 | return struct { |
| 153 | *responseWriterDelegator |
| 154 | http.Hijacker |
| 155 | http.Flusher |
| 156 | http.CloseNotifier |
| 157 | }{d, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} |
| 158 | } |
| 159 | pickDelegator[readerFrom] = func(d *responseWriterDelegator) delegator { // 8 |
| 160 | return readerFromDelegator{d} |
| 161 | } |
| 162 | pickDelegator[readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 9 |
| 163 | return struct { |
| 164 | *responseWriterDelegator |
| 165 | io.ReaderFrom |
| 166 | http.CloseNotifier |
| 167 | }{d, readerFromDelegator{d}, closeNotifierDelegator{d}} |
| 168 | } |
| 169 | pickDelegator[readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 10 |
| 170 | return struct { |
| 171 | *responseWriterDelegator |
| 172 | io.ReaderFrom |
| 173 | http.Flusher |
| 174 | }{d, readerFromDelegator{d}, flusherDelegator{d}} |
| 175 | } |
| 176 | pickDelegator[readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 11 |
| 177 | return struct { |
| 178 | *responseWriterDelegator |
| 179 | io.ReaderFrom |
| 180 | http.Flusher |
| 181 | http.CloseNotifier |
| 182 | }{d, readerFromDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} |
| 183 | } |
| 184 | pickDelegator[readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 12 |
| 185 | return struct { |
| 186 | *responseWriterDelegator |
| 187 | io.ReaderFrom |
| 188 | http.Hijacker |
| 189 | }{d, readerFromDelegator{d}, hijackerDelegator{d}} |
| 190 | } |
| 191 | pickDelegator[readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 13 |
| 192 | return struct { |
| 193 | *responseWriterDelegator |
| 194 | io.ReaderFrom |
| 195 | http.Hijacker |
| 196 | http.CloseNotifier |
| 197 | }{d, readerFromDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}} |
| 198 | } |
| 199 | pickDelegator[readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 14 |
| 200 | return struct { |
| 201 | *responseWriterDelegator |
| 202 | io.ReaderFrom |
| 203 | http.Hijacker |
| 204 | http.Flusher |
| 205 | }{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}} |
| 206 | } |
| 207 | pickDelegator[readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 15 |
| 208 | return struct { |
| 209 | *responseWriterDelegator |
| 210 | io.ReaderFrom |
| 211 | http.Hijacker |
| 212 | http.Flusher |
| 213 | http.CloseNotifier |
| 214 | }{d, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} |
| 215 | } |
| 216 | pickDelegator[pusher] = func(d *responseWriterDelegator) delegator { // 16 |
| 217 | return pusherDelegator{d} |
| 218 | } |
| 219 | pickDelegator[pusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 17 |
| 220 | return struct { |
| 221 | *responseWriterDelegator |
| 222 | http.Pusher |
| 223 | http.CloseNotifier |
| 224 | }{d, pusherDelegator{d}, closeNotifierDelegator{d}} |
| 225 | } |
| 226 | pickDelegator[pusher+flusher] = func(d *responseWriterDelegator) delegator { // 18 |
| 227 | return struct { |
| 228 | *responseWriterDelegator |
| 229 | http.Pusher |
| 230 | http.Flusher |
| 231 | }{d, pusherDelegator{d}, flusherDelegator{d}} |
| 232 | } |
| 233 | pickDelegator[pusher+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 19 |
| 234 | return struct { |
| 235 | *responseWriterDelegator |
| 236 | http.Pusher |
| 237 | http.Flusher |
| 238 | http.CloseNotifier |
| 239 | }{d, pusherDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} |
| 240 | } |
| 241 | pickDelegator[pusher+hijacker] = func(d *responseWriterDelegator) delegator { // 20 |
| 242 | return struct { |
| 243 | *responseWriterDelegator |
| 244 | http.Pusher |
| 245 | http.Hijacker |
| 246 | }{d, pusherDelegator{d}, hijackerDelegator{d}} |
| 247 | } |
| 248 | pickDelegator[pusher+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 21 |
| 249 | return struct { |
| 250 | *responseWriterDelegator |
| 251 | http.Pusher |
| 252 | http.Hijacker |
| 253 | http.CloseNotifier |
| 254 | }{d, pusherDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}} |
| 255 | } |
| 256 | pickDelegator[pusher+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 22 |
| 257 | return struct { |
| 258 | *responseWriterDelegator |
| 259 | http.Pusher |
| 260 | http.Hijacker |
| 261 | http.Flusher |
| 262 | }{d, pusherDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}} |
| 263 | } |
| 264 | pickDelegator[pusher+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { //23 |
| 265 | return struct { |
| 266 | *responseWriterDelegator |
| 267 | http.Pusher |
| 268 | http.Hijacker |
| 269 | http.Flusher |
| 270 | http.CloseNotifier |
| 271 | }{d, pusherDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} |
| 272 | } |
| 273 | pickDelegator[pusher+readerFrom] = func(d *responseWriterDelegator) delegator { // 24 |
| 274 | return struct { |
| 275 | *responseWriterDelegator |
| 276 | http.Pusher |
| 277 | io.ReaderFrom |
| 278 | }{d, pusherDelegator{d}, readerFromDelegator{d}} |
| 279 | } |
| 280 | pickDelegator[pusher+readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 25 |
| 281 | return struct { |
| 282 | *responseWriterDelegator |
| 283 | http.Pusher |
| 284 | io.ReaderFrom |
| 285 | http.CloseNotifier |
| 286 | }{d, pusherDelegator{d}, readerFromDelegator{d}, closeNotifierDelegator{d}} |
| 287 | } |
| 288 | pickDelegator[pusher+readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 26 |
| 289 | return struct { |
| 290 | *responseWriterDelegator |
| 291 | http.Pusher |
| 292 | io.ReaderFrom |
| 293 | http.Flusher |
| 294 | }{d, pusherDelegator{d}, readerFromDelegator{d}, flusherDelegator{d}} |
| 295 | } |
| 296 | pickDelegator[pusher+readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 27 |
| 297 | return struct { |
| 298 | *responseWriterDelegator |
| 299 | http.Pusher |
| 300 | io.ReaderFrom |
| 301 | http.Flusher |
| 302 | http.CloseNotifier |
| 303 | }{d, pusherDelegator{d}, readerFromDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} |
| 304 | } |
| 305 | pickDelegator[pusher+readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 28 |
| 306 | return struct { |
| 307 | *responseWriterDelegator |
| 308 | http.Pusher |
| 309 | io.ReaderFrom |
| 310 | http.Hijacker |
| 311 | }{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}} |
| 312 | } |
| 313 | pickDelegator[pusher+readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 29 |
| 314 | return struct { |
| 315 | *responseWriterDelegator |
| 316 | http.Pusher |
| 317 | io.ReaderFrom |
| 318 | http.Hijacker |
| 319 | http.CloseNotifier |
| 320 | }{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, closeNotifierDelegator{d}} |
| 321 | } |
| 322 | pickDelegator[pusher+readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 30 |
| 323 | return struct { |
| 324 | *responseWriterDelegator |
| 325 | http.Pusher |
| 326 | io.ReaderFrom |
| 327 | http.Hijacker |
| 328 | http.Flusher |
| 329 | }{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}} |
| 330 | } |
| 331 | pickDelegator[pusher+readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 31 |
| 332 | return struct { |
| 333 | *responseWriterDelegator |
| 334 | http.Pusher |
| 335 | io.ReaderFrom |
| 336 | http.Hijacker |
| 337 | http.Flusher |
| 338 | http.CloseNotifier |
| 339 | }{d, pusherDelegator{d}, readerFromDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}, closeNotifierDelegator{d}} |
| 340 | } |
| 341 | } |
| 342 | |
| 343 | func newDelegator(w http.ResponseWriter, observeWriteHeaderFunc func(int)) delegator { |
| 344 | d := &responseWriterDelegator{ |
| 345 | ResponseWriter: w, |
| 346 | observeWriteHeader: observeWriteHeaderFunc, |
| 347 | } |
| 348 | |
| 349 | id := 0 |
khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 350 | //nolint:staticcheck // Ignore SA1019. http.CloseNotifier is deprecated but we keep it here to not break existing users. |
khenaidoo | ab1f7bd | 2019-11-14 14:00:27 -0500 | [diff] [blame] | 351 | if _, ok := w.(http.CloseNotifier); ok { |
| 352 | id += closeNotifier |
| 353 | } |
| 354 | if _, ok := w.(http.Flusher); ok { |
| 355 | id += flusher |
| 356 | } |
| 357 | if _, ok := w.(http.Hijacker); ok { |
| 358 | id += hijacker |
| 359 | } |
| 360 | if _, ok := w.(io.ReaderFrom); ok { |
| 361 | id += readerFrom |
| 362 | } |
| 363 | if _, ok := w.(http.Pusher); ok { |
| 364 | id += pusher |
| 365 | } |
| 366 | |
| 367 | return pickDelegator[id](d) |
| 368 | } |