Fast and extensible multi-platform HTTP/1-2-3 web server with automatic HTTPS
Mirrored from https://github.com/Slazee/caddy.git
Synced Nov 11, 01:00 UTC
| 1 | // Copyright 2015 Matthew Holt and The Caddy 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 reverseproxy |
| 16 | |
| 17 | import ( |
| 18 | "crypto/hmac" |
| 19 | "crypto/sha256" |
| 20 | "encoding/hex" |
| 21 | "encoding/json" |
| 22 | "fmt" |
| 23 | weakrand "math/rand/v2" |
| 24 | "net" |
| 25 | "net/http" |
| 26 | "strconv" |
| 27 | "strings" |
| 28 | "sync/atomic" |
| 29 | "time" |
| 30 | |
| 31 | "github.com/cespare/xxhash/v2" |
| 32 | |
| 33 | "github.com/caddyserver/caddy/v2" |
| 34 | "github.com/caddyserver/caddy/v2/caddyconfig" |
| 35 | "github.com/caddyserver/caddy/v2/caddyconfig/caddyfile" |
| 36 | "github.com/caddyserver/caddy/v2/modules/caddyhttp" |
| 37 | ) |
| 38 | |
| 39 | func init() { |
| 40 | caddy.RegisterModule(RandomSelection{}) |
| 41 | caddy.RegisterModule(RandomChoiceSelection{}) |
| 42 | caddy.RegisterModule(LeastConnSelection{}) |
| 43 | caddy.RegisterModule(new(RoundRobinSelection)) |
| 44 | caddy.RegisterModule(new(WeightedRoundRobinSelection)) |
| 45 | caddy.RegisterModule(FirstSelection{}) |
| 46 | caddy.RegisterModule(IPHashSelection{}) |
| 47 | caddy.RegisterModule(ClientIPHashSelection{}) |
| 48 | caddy.RegisterModule(URIHashSelection{}) |
| 49 | caddy.RegisterModule(QueryHashSelection{}) |
| 50 | caddy.RegisterModule(HeaderHashSelection{}) |
| 51 | caddy.RegisterModule(CookieHashSelection{}) |
| 52 | } |
| 53 | |
| 54 | // RandomSelection is a policy that selects |
| 55 | // an available host at random. |
| 56 | type RandomSelection struct{} |
| 57 | |
| 58 | // CaddyModule returns the Caddy module information. |
| 59 | func (RandomSelection) CaddyModule() caddy.ModuleInfo { |
| 60 | return caddy.ModuleInfo{ |
| 61 | ID: "http.reverse_proxy.selection_policies.random", |
| 62 | New: func() caddy.Module { return new(RandomSelection) }, |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | // Select returns an available host, if any. |
| 67 | func (r RandomSelection) Select(pool UpstreamPool, request *http.Request, _ http.ResponseWriter) *Upstream { |
| 68 | return selectRandomHost(pool) |
| 69 | } |
| 70 | |
| 71 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 72 | func (r *RandomSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 73 | d.Next() // consume policy name |
| 74 | if d.NextArg() { |
| 75 | return d.ArgErr() |
| 76 | } |
| 77 | return nil |
| 78 | } |
| 79 | |
| 80 | // WeightedRoundRobinSelection is a policy that selects |
| 81 | // a host based on weighted round-robin ordering. |
| 82 | type WeightedRoundRobinSelection struct { |
| 83 | // The weight of each upstream in order, |
| 84 | // corresponding with the list of upstreams configured. |
| 85 | Weights []int `json:"weights,omitempty"` |
| 86 | index atomic.Uint32 |
| 87 | totalWeight int |
| 88 | } |
| 89 | |
| 90 | // CaddyModule returns the Caddy module information. |
| 91 | func (*WeightedRoundRobinSelection) CaddyModule() caddy.ModuleInfo { |
| 92 | return caddy.ModuleInfo{ |
| 93 | ID: "http.reverse_proxy.selection_policies.weighted_round_robin", |
| 94 | New: func() caddy.Module { |
| 95 | return new(WeightedRoundRobinSelection) |
| 96 | }, |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 101 | func (r *WeightedRoundRobinSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 102 | d.Next() // consume policy name |
| 103 | |
| 104 | args := d.RemainingArgs() |
| 105 | if len(args) == 0 { |
| 106 | return d.ArgErr() |
| 107 | } |
| 108 | |
| 109 | for _, weight := range args { |
| 110 | weightInt, err := strconv.Atoi(weight) |
| 111 | if err != nil { |
| 112 | return d.Errf("invalid weight value '%s': %v", weight, err) |
| 113 | } |
| 114 | if weightInt < 0 { |
| 115 | return d.Errf("invalid weight value '%s': weight should be non-negative", weight) |
| 116 | } |
| 117 | r.Weights = append(r.Weights, weightInt) |
| 118 | } |
| 119 | return nil |
| 120 | } |
| 121 | |
| 122 | // Provision sets up r. |
| 123 | func (r *WeightedRoundRobinSelection) Provision(ctx caddy.Context) error { |
| 124 | for _, weight := range r.Weights { |
| 125 | r.totalWeight += weight |
| 126 | } |
| 127 | return nil |
| 128 | } |
| 129 | |
| 130 | // Validate ensures that r's configuration is valid |
| 131 | func (r *WeightedRoundRobinSelection) Validate() error { |
| 132 | if r.totalWeight <= 0 { |
| 133 | return fmt.Errorf("weighted_round_robin requires at least one upstream with a positive weight") |
| 134 | } |
| 135 | for _, weight := range r.Weights { |
| 136 | if weight < 0 { |
| 137 | return fmt.Errorf("weight of an upstream cannot be negative") |
| 138 | } |
| 139 | } |
| 140 | return nil |
| 141 | } |
| 142 | |
| 143 | // Select returns an available host, if any. |
| 144 | func (r *WeightedRoundRobinSelection) Select(pool UpstreamPool, _ *http.Request, _ http.ResponseWriter) *Upstream { |
| 145 | type weightedUpstream struct { |
| 146 | upstream *Upstream |
| 147 | weight int |
| 148 | } |
| 149 | upstreams := make([]weightedUpstream, 0, len(pool)) |
| 150 | var totalWeight int |
| 151 | for i, upstream := range pool { |
| 152 | if i >= len(r.Weights) || r.Weights[i] <= 0 || !upstream.Available() { |
| 153 | continue |
| 154 | } |
| 155 | upstreams = append(upstreams, weightedUpstream{upstream, r.Weights[i]}) |
| 156 | totalWeight += r.Weights[i] |
| 157 | } |
| 158 | if totalWeight == 0 { |
| 159 | return nil |
| 160 | } |
| 161 | |
| 162 | currentWeight := uint64(r.index.Add(1)) % uint64(totalWeight) |
| 163 | for _, upstream := range upstreams { |
| 164 | if currentWeight < uint64(upstream.weight) { |
| 165 | return upstream.upstream |
| 166 | } |
| 167 | currentWeight -= uint64(upstream.weight) |
| 168 | } |
| 169 | return nil |
| 170 | } |
| 171 | |
| 172 | // RandomChoiceSelection is a policy that selects |
| 173 | // two or more available hosts at random, then |
| 174 | // chooses the one with the least load. |
| 175 | type RandomChoiceSelection struct { |
| 176 | // The size of the sub-pool created from the larger upstream pool. The default value |
| 177 | // is 2 and the maximum at selection time is the size of the upstream pool. |
| 178 | Choose int `json:"choose,omitempty"` |
| 179 | } |
| 180 | |
| 181 | // CaddyModule returns the Caddy module information. |
| 182 | func (RandomChoiceSelection) CaddyModule() caddy.ModuleInfo { |
| 183 | return caddy.ModuleInfo{ |
| 184 | ID: "http.reverse_proxy.selection_policies.random_choose", |
| 185 | New: func() caddy.Module { return new(RandomChoiceSelection) }, |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 190 | func (r *RandomChoiceSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 191 | d.Next() // consume policy name |
| 192 | |
| 193 | if !d.NextArg() { |
| 194 | return d.ArgErr() |
| 195 | } |
| 196 | chooseStr := d.Val() |
| 197 | choose, err := strconv.Atoi(chooseStr) |
| 198 | if err != nil { |
| 199 | return d.Errf("invalid choice value '%s': %v", chooseStr, err) |
| 200 | } |
| 201 | r.Choose = choose |
| 202 | return nil |
| 203 | } |
| 204 | |
| 205 | // Provision sets up r. |
| 206 | func (r *RandomChoiceSelection) Provision(ctx caddy.Context) error { |
| 207 | if r.Choose == 0 { |
| 208 | r.Choose = 2 |
| 209 | } |
| 210 | return nil |
| 211 | } |
| 212 | |
| 213 | // Validate ensures that r's configuration is valid. |
| 214 | func (r RandomChoiceSelection) Validate() error { |
| 215 | if r.Choose < 2 { |
| 216 | return fmt.Errorf("choose must be at least 2") |
| 217 | } |
| 218 | return nil |
| 219 | } |
| 220 | |
| 221 | // Select returns an available host, if any. |
| 222 | func (r RandomChoiceSelection) Select(pool UpstreamPool, _ *http.Request, _ http.ResponseWriter) *Upstream { |
| 223 | k := min(r.Choose, len(pool)) |
| 224 | |
| 225 | // reservoir sampling (Algorithm R) over the available upstreams: |
| 226 | // the first k available upstreams fill the reservoir, then each |
| 227 | // subsequent one replaces a random reservoir entry with probability |
| 228 | // k/n, so every available upstream is sampled uniformly |
| 229 | choices := make([]*Upstream, 0, k) |
| 230 | var available int |
| 231 | for _, upstream := range pool { |
| 232 | if !upstream.Available() { |
| 233 | continue |
| 234 | } |
| 235 | available++ |
| 236 | if len(choices) < k { |
| 237 | choices = append(choices, upstream) |
| 238 | continue |
| 239 | } |
| 240 | j := weakrand.IntN(available) //nolint:gosec |
| 241 | if j < k { |
| 242 | choices[j] = upstream |
| 243 | } |
| 244 | } |
| 245 | return leastRequests(choices) |
| 246 | } |
| 247 | |
| 248 | // LeastConnSelection is a policy that selects the |
| 249 | // host with the least active requests. If multiple |
| 250 | // hosts have the same fewest number, one is chosen |
| 251 | // randomly. The term "conn" or "connection" is used |
| 252 | // in this policy name due to its similar meaning in |
| 253 | // other software, but our load balancer actually |
| 254 | // counts active requests rather than connections, |
| 255 | // since these days requests are multiplexed onto |
| 256 | // shared connections. |
| 257 | type LeastConnSelection struct{} |
| 258 | |
| 259 | // CaddyModule returns the Caddy module information. |
| 260 | func (LeastConnSelection) CaddyModule() caddy.ModuleInfo { |
| 261 | return caddy.ModuleInfo{ |
| 262 | ID: "http.reverse_proxy.selection_policies.least_conn", |
| 263 | New: func() caddy.Module { return new(LeastConnSelection) }, |
| 264 | } |
| 265 | } |
| 266 | |
| 267 | // Select selects the up host with the least number of connections in the |
| 268 | // pool. If more than one host has the same least number of connections, |
| 269 | // one of the hosts is chosen at random. |
| 270 | func (LeastConnSelection) Select(pool UpstreamPool, _ *http.Request, _ http.ResponseWriter) *Upstream { |
| 271 | var bestHost *Upstream |
| 272 | var count int |
| 273 | leastReqs := -1 |
| 274 | |
| 275 | for _, host := range pool { |
| 276 | if !host.Available() { |
| 277 | continue |
| 278 | } |
| 279 | numReqs := host.NumRequests() |
| 280 | if leastReqs == -1 || numReqs < leastReqs { |
| 281 | leastReqs = numReqs |
| 282 | count = 0 |
| 283 | } |
| 284 | |
| 285 | // among hosts with same least connections, perform a reservoir |
| 286 | // sample: https://en.wikipedia.org/wiki/Reservoir_sampling |
| 287 | if numReqs == leastReqs { |
| 288 | count++ |
| 289 | if count == 1 || weakrand.IntN(count) == 0 { //nolint:gosec |
| 290 | bestHost = host |
| 291 | } |
| 292 | } |
| 293 | } |
| 294 | |
| 295 | return bestHost |
| 296 | } |
| 297 | |
| 298 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 299 | func (r *LeastConnSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 300 | d.Next() // consume policy name |
| 301 | if d.NextArg() { |
| 302 | return d.ArgErr() |
| 303 | } |
| 304 | return nil |
| 305 | } |
| 306 | |
| 307 | // RoundRobinSelection is a policy that selects |
| 308 | // a host based on round-robin ordering. |
| 309 | type RoundRobinSelection struct { |
| 310 | robin atomic.Uint32 |
| 311 | } |
| 312 | |
| 313 | // CaddyModule returns the Caddy module information. |
| 314 | func (*RoundRobinSelection) CaddyModule() caddy.ModuleInfo { |
| 315 | return caddy.ModuleInfo{ |
| 316 | ID: "http.reverse_proxy.selection_policies.round_robin", |
| 317 | New: func() caddy.Module { return new(RoundRobinSelection) }, |
| 318 | } |
| 319 | } |
| 320 | |
| 321 | // Select returns an available host, if any. |
| 322 | func (r *RoundRobinSelection) Select(pool UpstreamPool, _ *http.Request, _ http.ResponseWriter) *Upstream { |
| 323 | n := uint32(len(pool)) |
| 324 | if n == 0 { |
| 325 | return nil |
| 326 | } |
| 327 | for range n { |
| 328 | robin := r.robin.Add(1) |
| 329 | host := pool[robin%n] |
| 330 | if host.Available() { |
| 331 | return host |
| 332 | } |
| 333 | } |
| 334 | return nil |
| 335 | } |
| 336 | |
| 337 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 338 | func (r *RoundRobinSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 339 | d.Next() // consume policy name |
| 340 | if d.NextArg() { |
| 341 | return d.ArgErr() |
| 342 | } |
| 343 | return nil |
| 344 | } |
| 345 | |
| 346 | // FirstSelection is a policy that selects |
| 347 | // the first available host. |
| 348 | type FirstSelection struct{} |
| 349 | |
| 350 | // CaddyModule returns the Caddy module information. |
| 351 | func (FirstSelection) CaddyModule() caddy.ModuleInfo { |
| 352 | return caddy.ModuleInfo{ |
| 353 | ID: "http.reverse_proxy.selection_policies.first", |
| 354 | New: func() caddy.Module { return new(FirstSelection) }, |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | // Select returns an available host, if any. |
| 359 | func (FirstSelection) Select(pool UpstreamPool, _ *http.Request, _ http.ResponseWriter) *Upstream { |
| 360 | for _, host := range pool { |
| 361 | if host.Available() { |
| 362 | return host |
| 363 | } |
| 364 | } |
| 365 | return nil |
| 366 | } |
| 367 | |
| 368 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 369 | func (r *FirstSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 370 | d.Next() // consume policy name |
| 371 | if d.NextArg() { |
| 372 | return d.ArgErr() |
| 373 | } |
| 374 | return nil |
| 375 | } |
| 376 | |
| 377 | // IPHashSelection is a policy that selects a host |
| 378 | // based on hashing the remote IP of the request. |
| 379 | type IPHashSelection struct{} |
| 380 | |
| 381 | // CaddyModule returns the Caddy module information. |
| 382 | func (IPHashSelection) CaddyModule() caddy.ModuleInfo { |
| 383 | return caddy.ModuleInfo{ |
| 384 | ID: "http.reverse_proxy.selection_policies.ip_hash", |
| 385 | New: func() caddy.Module { return new(IPHashSelection) }, |
| 386 | } |
| 387 | } |
| 388 | |
| 389 | // Select returns an available host, if any. |
| 390 | func (IPHashSelection) Select(pool UpstreamPool, req *http.Request, _ http.ResponseWriter) *Upstream { |
| 391 | clientIP, _, err := net.SplitHostPort(req.RemoteAddr) |
| 392 | if err != nil { |
| 393 | clientIP = req.RemoteAddr |
| 394 | } |
| 395 | return hostByHashing(pool, clientIP) |
| 396 | } |
| 397 | |
| 398 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 399 | func (r *IPHashSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 400 | d.Next() // consume policy name |
| 401 | if d.NextArg() { |
| 402 | return d.ArgErr() |
| 403 | } |
| 404 | return nil |
| 405 | } |
| 406 | |
| 407 | // ClientIPHashSelection is a policy that selects a host |
| 408 | // based on hashing the client IP of the request, as determined |
| 409 | // by the HTTP app's trusted proxies settings. |
| 410 | type ClientIPHashSelection struct{} |
| 411 | |
| 412 | // CaddyModule returns the Caddy module information. |
| 413 | func (ClientIPHashSelection) CaddyModule() caddy.ModuleInfo { |
| 414 | return caddy.ModuleInfo{ |
| 415 | ID: "http.reverse_proxy.selection_policies.client_ip_hash", |
| 416 | New: func() caddy.Module { return new(ClientIPHashSelection) }, |
| 417 | } |
| 418 | } |
| 419 | |
| 420 | // Select returns an available host, if any. |
| 421 | func (ClientIPHashSelection) Select(pool UpstreamPool, req *http.Request, _ http.ResponseWriter) *Upstream { |
| 422 | address := caddyhttp.GetVar(req.Context(), caddyhttp.ClientIPVarKey).(string) |
| 423 | clientIP, _, err := net.SplitHostPort(address) |
| 424 | if err != nil { |
| 425 | clientIP = address // no port |
| 426 | } |
| 427 | return hostByHashing(pool, clientIP) |
| 428 | } |
| 429 | |
| 430 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 431 | func (r *ClientIPHashSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 432 | d.Next() // consume policy name |
| 433 | if d.NextArg() { |
| 434 | return d.ArgErr() |
| 435 | } |
| 436 | return nil |
| 437 | } |
| 438 | |
| 439 | // URIHashSelection is a policy that selects a |
| 440 | // host by hashing the request URI. |
| 441 | type URIHashSelection struct{} |
| 442 | |
| 443 | // CaddyModule returns the Caddy module information. |
| 444 | func (URIHashSelection) CaddyModule() caddy.ModuleInfo { |
| 445 | return caddy.ModuleInfo{ |
| 446 | ID: "http.reverse_proxy.selection_policies.uri_hash", |
| 447 | New: func() caddy.Module { return new(URIHashSelection) }, |
| 448 | } |
| 449 | } |
| 450 | |
| 451 | // Select returns an available host, if any. |
| 452 | func (URIHashSelection) Select(pool UpstreamPool, req *http.Request, _ http.ResponseWriter) *Upstream { |
| 453 | return hostByHashing(pool, req.RequestURI) |
| 454 | } |
| 455 | |
| 456 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 457 | func (r *URIHashSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 458 | d.Next() // consume policy name |
| 459 | if d.NextArg() { |
| 460 | return d.ArgErr() |
| 461 | } |
| 462 | return nil |
| 463 | } |
| 464 | |
| 465 | // QueryHashSelection is a policy that selects |
| 466 | // a host based on a given request query parameter. |
| 467 | type QueryHashSelection struct { |
| 468 | // The query key whose value is to be hashed and used for upstream selection. |
| 469 | Key string `json:"key,omitempty"` |
| 470 | |
| 471 | // The fallback policy to use if the query key is not present. Defaults to `random`. |
| 472 | FallbackRaw json.RawMessage `json:"fallback,omitempty" caddy:"namespace=http.reverse_proxy.selection_policies inline_key=policy"` |
| 473 | fallback Selector |
| 474 | } |
| 475 | |
| 476 | // CaddyModule returns the Caddy module information. |
| 477 | func (QueryHashSelection) CaddyModule() caddy.ModuleInfo { |
| 478 | return caddy.ModuleInfo{ |
| 479 | ID: "http.reverse_proxy.selection_policies.query", |
| 480 | New: func() caddy.Module { return new(QueryHashSelection) }, |
| 481 | } |
| 482 | } |
| 483 | |
| 484 | // Provision sets up the module. |
| 485 | func (s *QueryHashSelection) Provision(ctx caddy.Context) error { |
| 486 | if s.Key == "" { |
| 487 | return fmt.Errorf("query key is required") |
| 488 | } |
| 489 | if s.FallbackRaw == nil { |
| 490 | s.FallbackRaw = caddyconfig.JSONModuleObject(RandomSelection{}, "policy", "random", nil) |
| 491 | } |
| 492 | mod, err := ctx.LoadModule(s, "FallbackRaw") |
| 493 | if err != nil { |
| 494 | return fmt.Errorf("loading fallback selection policy: %s", err) |
| 495 | } |
| 496 | s.fallback = mod.(Selector) |
| 497 | return nil |
| 498 | } |
| 499 | |
| 500 | // Select returns an available host, if any. |
| 501 | func (s QueryHashSelection) Select(pool UpstreamPool, req *http.Request, _ http.ResponseWriter) *Upstream { |
| 502 | // Since the query may have multiple values for the same key, |
| 503 | // we'll join them to avoid a problem where the user can control |
| 504 | // the upstream that the request goes to by sending multiple values |
| 505 | // for the same key, when the upstream only considers the first value. |
| 506 | // Keep in mind that a client changing the order of the values may |
| 507 | // affect which upstream is selected, but this is a semantically |
| 508 | // different request, because the order of the values is significant. |
| 509 | vals := strings.Join(req.URL.Query()[s.Key], ",") |
| 510 | if vals == "" { |
| 511 | return s.fallback.Select(pool, req, nil) |
| 512 | } |
| 513 | return hostByHashing(pool, vals) |
| 514 | } |
| 515 | |
| 516 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 517 | func (s *QueryHashSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 518 | d.Next() // consume policy name |
| 519 | |
| 520 | if !d.NextArg() { |
| 521 | return d.ArgErr() |
| 522 | } |
| 523 | s.Key = d.Val() |
| 524 | |
| 525 | for d.NextBlock(0) { |
| 526 | switch d.Val() { |
| 527 | case "fallback": |
| 528 | if !d.NextArg() { |
| 529 | return d.ArgErr() |
| 530 | } |
| 531 | if s.FallbackRaw != nil { |
| 532 | return d.Err("fallback selection policy already specified") |
| 533 | } |
| 534 | mod, err := loadFallbackPolicy(d) |
| 535 | if err != nil { |
| 536 | return err |
| 537 | } |
| 538 | s.FallbackRaw = mod |
| 539 | default: |
| 540 | return d.Errf("unrecognized option '%s'", d.Val()) |
| 541 | } |
| 542 | } |
| 543 | return nil |
| 544 | } |
| 545 | |
| 546 | // HeaderHashSelection is a policy that selects |
| 547 | // a host based on a given request header. |
| 548 | type HeaderHashSelection struct { |
| 549 | // The HTTP header field whose value is to be hashed and used for upstream selection. |
| 550 | Field string `json:"field,omitempty"` |
| 551 | |
| 552 | // The fallback policy to use if the header is not present. Defaults to `random`. |
| 553 | FallbackRaw json.RawMessage `json:"fallback,omitempty" caddy:"namespace=http.reverse_proxy.selection_policies inline_key=policy"` |
| 554 | fallback Selector |
| 555 | } |
| 556 | |
| 557 | // CaddyModule returns the Caddy module information. |
| 558 | func (HeaderHashSelection) CaddyModule() caddy.ModuleInfo { |
| 559 | return caddy.ModuleInfo{ |
| 560 | ID: "http.reverse_proxy.selection_policies.header", |
| 561 | New: func() caddy.Module { return new(HeaderHashSelection) }, |
| 562 | } |
| 563 | } |
| 564 | |
| 565 | // Provision sets up the module. |
| 566 | func (s *HeaderHashSelection) Provision(ctx caddy.Context) error { |
| 567 | if s.Field == "" { |
| 568 | return fmt.Errorf("header field is required") |
| 569 | } |
| 570 | if s.FallbackRaw == nil { |
| 571 | s.FallbackRaw = caddyconfig.JSONModuleObject(RandomSelection{}, "policy", "random", nil) |
| 572 | } |
| 573 | mod, err := ctx.LoadModule(s, "FallbackRaw") |
| 574 | if err != nil { |
| 575 | return fmt.Errorf("loading fallback selection policy: %s", err) |
| 576 | } |
| 577 | s.fallback = mod.(Selector) |
| 578 | return nil |
| 579 | } |
| 580 | |
| 581 | // Select returns an available host, if any. |
| 582 | func (s HeaderHashSelection) Select(pool UpstreamPool, req *http.Request, _ http.ResponseWriter) *Upstream { |
| 583 | // The Host header should be obtained from the req.Host field |
| 584 | // since net/http removes it from the header map. |
| 585 | if s.Field == "Host" && req.Host != "" { |
| 586 | return hostByHashing(pool, req.Host) |
| 587 | } |
| 588 | |
| 589 | val := req.Header.Get(s.Field) |
| 590 | if val == "" { |
| 591 | return s.fallback.Select(pool, req, nil) |
| 592 | } |
| 593 | return hostByHashing(pool, val) |
| 594 | } |
| 595 | |
| 596 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. |
| 597 | func (s *HeaderHashSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 598 | d.Next() // consume policy name |
| 599 | |
| 600 | if !d.NextArg() { |
| 601 | return d.ArgErr() |
| 602 | } |
| 603 | s.Field = d.Val() |
| 604 | |
| 605 | for d.NextBlock(0) { |
| 606 | switch d.Val() { |
| 607 | case "fallback": |
| 608 | if !d.NextArg() { |
| 609 | return d.ArgErr() |
| 610 | } |
| 611 | if s.FallbackRaw != nil { |
| 612 | return d.Err("fallback selection policy already specified") |
| 613 | } |
| 614 | mod, err := loadFallbackPolicy(d) |
| 615 | if err != nil { |
| 616 | return err |
| 617 | } |
| 618 | s.FallbackRaw = mod |
| 619 | default: |
| 620 | return d.Errf("unrecognized option '%s'", d.Val()) |
| 621 | } |
| 622 | } |
| 623 | return nil |
| 624 | } |
| 625 | |
| 626 | // CookieHashSelection is a policy that selects |
| 627 | // a host based on a given cookie name. |
| 628 | type CookieHashSelection struct { |
| 629 | // The HTTP cookie name whose value is to be hashed and used for upstream selection. |
| 630 | Name string `json:"name,omitempty"` |
| 631 | // Secret to hash (Hmac256) chosen upstream in cookie |
| 632 | Secret string `json:"secret,omitempty"` //nolint:gosec // yes it's exported because it needs to encode to JSON |
| 633 | // The cookie's Max-Age before it expires. Default is no expiry. |
| 634 | MaxAge caddy.Duration `json:"max_age,omitempty"` |
| 635 | |
| 636 | // The fallback policy to use if the cookie is not present. Defaults to `random`. |
| 637 | FallbackRaw json.RawMessage `json:"fallback,omitempty" caddy:"namespace=http.reverse_proxy.selection_policies inline_key=policy"` |
| 638 | fallback Selector |
| 639 | } |
| 640 | |
| 641 | // CaddyModule returns the Caddy module information. |
| 642 | func (CookieHashSelection) CaddyModule() caddy.ModuleInfo { |
| 643 | return caddy.ModuleInfo{ |
| 644 | ID: "http.reverse_proxy.selection_policies.cookie", |
| 645 | New: func() caddy.Module { return new(CookieHashSelection) }, |
| 646 | } |
| 647 | } |
| 648 | |
| 649 | // Provision sets up the module. |
| 650 | func (s *CookieHashSelection) Provision(ctx caddy.Context) error { |
| 651 | if s.Name == "" { |
| 652 | s.Name = "lb" |
| 653 | } |
| 654 | if s.FallbackRaw == nil { |
| 655 | s.FallbackRaw = caddyconfig.JSONModuleObject(RandomSelection{}, "policy", "random", nil) |
| 656 | } |
| 657 | mod, err := ctx.LoadModule(s, "FallbackRaw") |
| 658 | if err != nil { |
| 659 | return fmt.Errorf("loading fallback selection policy: %s", err) |
| 660 | } |
| 661 | s.fallback = mod.(Selector) |
| 662 | return nil |
| 663 | } |
| 664 | |
| 665 | // Select returns an available host, if any. |
| 666 | func (s CookieHashSelection) Select(pool UpstreamPool, req *http.Request, w http.ResponseWriter) *Upstream { |
| 667 | // selects a new Host using the fallback policy (typically random) |
| 668 | // and write a sticky session cookie to the response. |
| 669 | selectNewHost := func() *Upstream { |
| 670 | upstream := s.fallback.Select(pool, req, w) |
| 671 | if upstream == nil { |
| 672 | return nil |
| 673 | } |
| 674 | sha, err := hashCookie(s.Secret, upstream.Dial) |
| 675 | if err != nil { |
| 676 | return upstream |
| 677 | } |
| 678 | cookie := &http.Cookie{ |
| 679 | Name: s.Name, |
| 680 | Value: sha, |
| 681 | Path: "/", |
| 682 | Secure: false, |
| 683 | HttpOnly: true, |
| 684 | SameSite: http.SameSiteLaxMode, |
| 685 | } |
| 686 | isProxyHttps := false |
| 687 | if trusted, ok := caddyhttp.GetVar(req.Context(), caddyhttp.TrustedProxyVarKey).(bool); ok && trusted { |
| 688 | xfp, xfpOk, _ := lastHeaderValue(req.Header, "X-Forwarded-Proto") |
| 689 | isProxyHttps = xfpOk && xfp == "https" |
| 690 | } |
| 691 | if req.TLS != nil || isProxyHttps { |
| 692 | cookie.Secure = true |
| 693 | cookie.SameSite = http.SameSiteNoneMode |
| 694 | } |
| 695 | if s.MaxAge > 0 { |
| 696 | cookie.MaxAge = int(time.Duration(s.MaxAge).Seconds()) |
| 697 | } |
| 698 | http.SetCookie(w, cookie) |
| 699 | return upstream |
| 700 | } |
| 701 | |
| 702 | cookie, err := req.Cookie(s.Name) |
| 703 | // If there's no cookie, select a host using the fallback policy |
| 704 | if err != nil || cookie == nil { |
| 705 | return selectNewHost() |
| 706 | } |
| 707 | // If the cookie is present, loop over the available upstreams until we find a match |
| 708 | cookieValue := cookie.Value |
| 709 | for _, upstream := range pool { |
| 710 | if !upstream.Available() { |
| 711 | continue |
| 712 | } |
| 713 | sha, err := hashCookie(s.Secret, upstream.Dial) |
| 714 | if err == nil && hmac.Equal([]byte(sha), []byte(cookieValue)) { |
| 715 | return upstream |
| 716 | } |
| 717 | } |
| 718 | // If there is no matching host, select a host using the fallback policy |
| 719 | return selectNewHost() |
| 720 | } |
| 721 | |
| 722 | // UnmarshalCaddyfile sets up the module from Caddyfile tokens. Syntax: |
| 723 | // |
| 724 | // lb_policy cookie [<name> [<secret>]] { |
| 725 | // fallback <policy> |
| 726 | // max_age <duration> |
| 727 | // } |
| 728 | // |
| 729 | // By default name is `lb` |
| 730 | func (s *CookieHashSelection) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { |
| 731 | args := d.RemainingArgs() |
| 732 | switch len(args) { |
| 733 | case 1: |
| 734 | case 2: |
| 735 | s.Name = args[1] |
| 736 | case 3: |
| 737 | s.Name = args[1] |
| 738 | s.Secret = args[2] |
| 739 | default: |
| 740 | return d.ArgErr() |
| 741 | } |
| 742 | for d.NextBlock(0) { |
| 743 | switch d.Val() { |
| 744 | case "fallback": |
| 745 | if !d.NextArg() { |
| 746 | return d.ArgErr() |
| 747 | } |
| 748 | if s.FallbackRaw != nil { |
| 749 | return d.Err("fallback selection policy already specified") |
| 750 | } |
| 751 | mod, err := loadFallbackPolicy(d) |
| 752 | if err != nil { |
| 753 | return err |
| 754 | } |
| 755 | s.FallbackRaw = mod |
| 756 | case "max_age": |
| 757 | if !d.NextArg() { |
| 758 | return d.ArgErr() |
| 759 | } |
| 760 | if s.MaxAge != 0 { |
| 761 | return d.Err("cookie max_age already specified") |
| 762 | } |
| 763 | maxAge, err := caddy.ParseDuration(d.Val()) |
| 764 | if err != nil { |
| 765 | return d.Errf("invalid duration: %s", d.Val()) |
| 766 | } |
| 767 | if maxAge <= 0 { |
| 768 | return d.Errf("invalid duration: %s, max_age should be non-zero and positive", d.Val()) |
| 769 | } |
| 770 | if d.NextArg() { |
| 771 | return d.ArgErr() |
| 772 | } |
| 773 | s.MaxAge = caddy.Duration(maxAge) |
| 774 | default: |
| 775 | return d.Errf("unrecognized option '%s'", d.Val()) |
| 776 | } |
| 777 | } |
| 778 | return nil |
| 779 | } |
| 780 | |
| 781 | // hashCookie hashes (HMAC 256) some data with the secret |
| 782 | func hashCookie(secret string, data string) (string, error) { |
| 783 | h := hmac.New(sha256.New, []byte(secret)) |
| 784 | _, err := h.Write([]byte(data)) |
| 785 | if err != nil { |
| 786 | return "", err |
| 787 | } |
| 788 | return hex.EncodeToString(h.Sum(nil)), nil |
| 789 | } |
| 790 | |
| 791 | // selectRandomHost returns a random available host |
| 792 | func selectRandomHost(pool []*Upstream) *Upstream { |
| 793 | // use reservoir sampling because the number of available |
| 794 | // hosts isn't known: https://en.wikipedia.org/wiki/Reservoir_sampling |
| 795 | var randomHost *Upstream |
| 796 | var count int |
| 797 | for _, upstream := range pool { |
| 798 | if !upstream.Available() { |
| 799 | continue |
| 800 | } |
| 801 | // (n % 1 == 0) holds for all n, therefore a |
| 802 | // upstream will always be chosen if there is at |
| 803 | // least one available |
| 804 | count++ |
| 805 | if weakrand.IntN(count) == 0 { //nolint:gosec |
| 806 | randomHost = upstream |
| 807 | } |
| 808 | } |
| 809 | return randomHost |
| 810 | } |
| 811 | |
| 812 | // leastRequests returns the host with the |
| 813 | // least number of active requests to it. |
| 814 | // If more than one host has the same |
| 815 | // least number of active requests, then |
| 816 | // one of those is chosen at random. |
| 817 | func leastRequests(upstreams []*Upstream) *Upstream { |
| 818 | if len(upstreams) == 0 { |
| 819 | return nil |
| 820 | } |
| 821 | var best []*Upstream |
| 822 | bestReqs := -1 |
| 823 | for _, upstream := range upstreams { |
| 824 | if upstream == nil { |
| 825 | continue |
| 826 | } |
| 827 | reqs := upstream.NumRequests() |
| 828 | if reqs == 0 { |
| 829 | return upstream |
| 830 | } |
| 831 | if reqs < bestReqs || bestReqs == -1 { |
| 832 | bestReqs = reqs |
| 833 | best = []*Upstream{upstream} |
| 834 | } else if reqs == bestReqs { |
| 835 | best = append(best, upstream) |
| 836 | } |
| 837 | } |
| 838 | if len(best) == 0 { |
| 839 | return nil |
| 840 | } |
| 841 | if len(best) == 1 { |
| 842 | return best[0] |
| 843 | } |
| 844 | return best[weakrand.IntN(len(best))] //nolint:gosec |
| 845 | } |
| 846 | |
| 847 | // hostByHashing returns an available host from pool based on a hashable string s. |
| 848 | func hostByHashing(pool []*Upstream, s string) *Upstream { |
| 849 | // Highest Random Weight (HRW, or "Rendezvous") hashing, |
| 850 | // guarantees stability when the list of upstreams changes; |
| 851 | // see https://medium.com/i0exception/rendezvous-hashing-8c00e2fb58b0, |
| 852 | // https://randorithms.com/2020/12/26/rendezvous-hashing.html, |
| 853 | // and https://en.wikipedia.org/wiki/Rendezvous_hashing. |
| 854 | var highestHash uint64 |
| 855 | var upstream *Upstream |
| 856 | for _, up := range pool { |
| 857 | if !up.Available() { |
| 858 | continue |
| 859 | } |
| 860 | h := hash(up.String() + s) // important to hash key and server together |
| 861 | if h > highestHash { |
| 862 | highestHash = h |
| 863 | upstream = up |
| 864 | } |
| 865 | } |
| 866 | return upstream |
| 867 | } |
| 868 | |
| 869 | // hash calculates a fast hash based on s. |
| 870 | func hash(s string) uint64 { |
| 871 | h := xxhash.New() |
| 872 | _, _ = h.Write([]byte(s)) |
| 873 | return h.Sum64() |
| 874 | } |
| 875 | |
| 876 | func loadFallbackPolicy(d *caddyfile.Dispenser) (json.RawMessage, error) { |
| 877 | name := d.Val() |
| 878 | modID := "http.reverse_proxy.selection_policies." + name |
| 879 | unm, err := caddyfile.UnmarshalModule(d, modID) |
| 880 | if err != nil { |
| 881 | return nil, err |
| 882 | } |
| 883 | sel, ok := unm.(Selector) |
| 884 | if !ok { |
| 885 | return nil, d.Errf("module %s (%T) is not a reverseproxy.Selector", modID, unm) |
| 886 | } |
| 887 | return caddyconfig.JSONModuleObject(sel, "policy", name, nil), nil |
| 888 | } |
| 889 | |
| 890 | // Interface guards |
| 891 | var ( |
| 892 | _ Selector = (*RandomSelection)(nil) |
| 893 | _ Selector = (*RandomChoiceSelection)(nil) |
| 894 | _ Selector = (*LeastConnSelection)(nil) |
| 895 | _ Selector = (*RoundRobinSelection)(nil) |
| 896 | _ Selector = (*WeightedRoundRobinSelection)(nil) |
| 897 | _ Selector = (*FirstSelection)(nil) |
| 898 | _ Selector = (*IPHashSelection)(nil) |
| 899 | _ Selector = (*ClientIPHashSelection)(nil) |
| 900 | _ Selector = (*URIHashSelection)(nil) |
| 901 | _ Selector = (*QueryHashSelection)(nil) |
| 902 | _ Selector = (*HeaderHashSelection)(nil) |
| 903 | _ Selector = (*CookieHashSelection)(nil) |
| 904 | |
| 905 | _ caddy.Validator = (*RandomChoiceSelection)(nil) |
| 906 | _ caddy.Validator = (*WeightedRoundRobinSelection)(nil) |
| 907 | |
| 908 | _ caddy.Provisioner = (*RandomChoiceSelection)(nil) |
| 909 | _ caddy.Provisioner = (*WeightedRoundRobinSelection)(nil) |
| 910 | |
| 911 | _ caddyfile.Unmarshaler = (*RandomChoiceSelection)(nil) |
| 912 | _ caddyfile.Unmarshaler = (*WeightedRoundRobinSelection)(nil) |
| 913 | ) |