1package chi 2 3// Radix tree implementation below is a based on the original work by 4// Armon Dadgar in https://github.com/armon/go-radix/blob/master/radix.go 5// (MIT licensed). It's been heavily modified for use as a HTTP routing tree. 6 7import ( 8 "fmt" 9 "math" 10 "net/http" 11 "regexp" 12 "sort" 13 "strconv" 14 "strings" 15) 16 17type methodTyp int 18 19const ( 20 mSTUB methodTyp = 1 << iota 21 mCONNECT 22 mDELETE 23 mGET 24 mHEAD 25 mOPTIONS 26 mPATCH 27 mPOST 28 mPUT 29 mTRACE 30) 31 32var mALL = mCONNECT | mDELETE | mGET | mHEAD | 33 mOPTIONS | mPATCH | mPOST | mPUT | mTRACE 34 35var methodMap = map[string]methodTyp{ 36 http.MethodConnect: mCONNECT, 37 http.MethodDelete: mDELETE, 38 http.MethodGet: mGET, 39 http.MethodHead: mHEAD, 40 http.MethodOptions: mOPTIONS, 41 http.MethodPatch: mPATCH, 42 http.MethodPost: mPOST, 43 http.MethodPut: mPUT, 44 http.MethodTrace: mTRACE, 45} 46 47// RegisterMethod adds support for custom HTTP method handlers, available 48// via Router#Method and Router#MethodFunc 49func RegisterMethod(method string) { 50 if method == "" { 51 return 52 } 53 method = strings.ToUpper(method) 54 if _, ok := methodMap[method]; ok { 55 return 56 } 57 n := len(methodMap) 58 if n > strconv.IntSize { 59 panic(fmt.Sprintf("chi: max number of methods reached (%d)", strconv.IntSize)) 60 } 61 mt := methodTyp(math.Exp2(float64(n))) 62 methodMap[method] = mt 63 mALL |= mt 64} 65 66type nodeTyp uint8 67 68const ( 69 ntStatic nodeTyp = iota // /home 70 ntRegexp // /{id:[0-9]+} 71 ntParam // /{user} 72 ntCatchAll // /api/v1/* 73) 74 75type node struct { 76 // node type: static, regexp, param, catchAll 77 typ nodeTyp 78 79 // first byte of the prefix 80 label byte 81 82 // first byte of the child prefix 83 tail byte 84 85 // prefix is the common prefix we ignore 86 prefix string 87 88 // regexp matcher for regexp nodes 89 rex *regexp.Regexp 90 91 // HTTP handler endpoints on the leaf node 92 endpoints endpoints 93 94 // subroutes on the leaf node 95 subroutes Routes 96 97 // child nodes should be stored in-order for iteration, 98 // in groups of the node type. 99 children [ntCatchAll + 1]nodes 100} 101 102// endpoints is a mapping of http method constants to handlers 103// for a given route. 104type endpoints map[methodTyp]*endpoint 105 106type endpoint struct { 107 // endpoint handler 108 handler http.Handler 109 110 // pattern is the routing pattern for handler nodes 111 pattern string 112 113 // parameter keys recorded on handler nodes 114 paramKeys []string 115} 116 117func (s endpoints) Value(method methodTyp) *endpoint { 118 mh, ok := s[method] 119 if !ok { 120 mh = &endpoint{} 121 s[method] = mh 122 } 123 return mh 124} 125 126func (n *node) InsertRoute(method methodTyp, pattern string, handler http.Handler) *node { 127 var parent *node 128 search := pattern 129 130 for { 131 // Handle key exhaustion 132 if len(search) == 0 { 133 // Insert or update the node's leaf handler 134 n.setEndpoint(method, handler, pattern) 135 return n 136 } 137 138 // We're going to be searching for a wild node next, 139 // in this case, we need to get the tail 140 var label = search[0] 141 var segTail byte 142 var segEndIdx int 143 var segTyp nodeTyp 144 var segRexpat string 145 if label == '{' || label == '*' { 146 segTyp, _, segRexpat, segTail, _, segEndIdx = patNextSegment(search) 147 } 148 149 var prefix string 150 if segTyp == ntRegexp { 151 prefix = segRexpat 152 } 153 154 // Look for the edge to attach to 155 parent = n 156 n = n.getEdge(segTyp, label, segTail, prefix) 157 158 // No edge, create one 159 if n == nil { 160 child := &node{label: label, tail: segTail, prefix: search} 161 hn := parent.addChild(child, search) 162 hn.setEndpoint(method, handler, pattern) 163 164 return hn 165 } 166 167 // Found an edge to match the pattern 168 169 if n.typ > ntStatic { 170 // We found a param node, trim the param from the search path and continue. 171 // This param/wild pattern segment would already be on the tree from a previous 172 // call to addChild when creating a new node. 173 search = search[segEndIdx:] 174 continue 175 } 176 177 // Static nodes fall below here. 178 // Determine longest prefix of the search key on match. 179 commonPrefix := longestPrefix(search, n.prefix) 180 if commonPrefix == len(n.prefix) { 181 // the common prefix is as long as the current node's prefix we're attempting to insert. 182 // keep the search going. 183 search = search[commonPrefix:] 184 continue 185 } 186 187 // Split the node 188 child := &node{ 189 typ: ntStatic, 190 prefix: search[:commonPrefix], 191 } 192 parent.replaceChild(search[0], segTail, child) 193 194 // Restore the existing node 195 n.label = n.prefix[commonPrefix] 196 n.prefix = n.prefix[commonPrefix:] 197 child.addChild(n, n.prefix) 198 199 // If the new key is a subset, set the method/handler on this node and finish. 200 search = search[commonPrefix:] 201 if len(search) == 0 { 202 child.setEndpoint(method, handler, pattern) 203 return child 204 } 205 206 // Create a new edge for the node 207 subchild := &node{ 208 typ: ntStatic, 209 label: search[0], 210 prefix: search, 211 } 212 hn := child.addChild(subchild, search) 213 hn.setEndpoint(method, handler, pattern) 214 return hn 215 } 216} 217 218// addChild appends the new `child` node to the tree using the `pattern` as the trie key. 219// For a URL router like chi's, we split the static, param, regexp and wildcard segments 220// into different nodes. In addition, addChild will recursively call itself until every 221// pattern segment is added to the url pattern tree as individual nodes, depending on type. 222func (n *node) addChild(child *node, prefix string) *node { 223 search := prefix 224 225 // handler leaf node added to the tree is the child. 226 // this may be overridden later down the flow 227 hn := child 228 229 // Parse next segment 230 segTyp, _, segRexpat, segTail, segStartIdx, segEndIdx := patNextSegment(search) 231 232 // Add child depending on next up segment 233 switch segTyp { 234 235 case ntStatic: 236 // Search prefix is all static (that is, has no params in path) 237 // noop 238 239 default: 240 // Search prefix contains a param, regexp or wildcard 241 242 if segTyp == ntRegexp { 243 rex, err := regexp.Compile(segRexpat) 244 if err != nil { 245 panic(fmt.Sprintf("chi: invalid regexp pattern '%s' in route param", segRexpat)) 246 } 247 child.prefix = segRexpat 248 child.rex = rex 249 } 250 251 if segStartIdx == 0 { 252 // Route starts with a param 253 child.typ = segTyp 254 255 if segTyp == ntCatchAll { 256 segStartIdx = -1 257 } else { 258 segStartIdx = segEndIdx 259 } 260 if segStartIdx < 0 { 261 segStartIdx = len(search) 262 } 263 child.tail = segTail // for params, we set the tail 264 265 if segStartIdx != len(search) { 266 // add static edge for the remaining part, split the end. 267 // its not possible to have adjacent param nodes, so its certainly 268 // going to be a static node next. 269 270 search = search[segStartIdx:] // advance search position 271 272 nn := &node{ 273 typ: ntStatic, 274 label: search[0], 275 prefix: search, 276 } 277 hn = child.addChild(nn, search) 278 } 279 280 } else if segStartIdx > 0 { 281 // Route has some param 282 283 // starts with a static segment 284 child.typ = ntStatic 285 child.prefix = search[:segStartIdx] 286 child.rex = nil 287 288 // add the param edge node 289 search = search[segStartIdx:] 290 291 nn := &node{ 292 typ: segTyp, 293 label: search[0], 294 tail: segTail, 295 } 296 hn = child.addChild(nn, search) 297 298 } 299 } 300 301 n.children[child.typ] = append(n.children[child.typ], child) 302 n.children[child.typ].Sort() 303 return hn 304} 305 306func (n *node) replaceChild(label, tail byte, child *node) { 307 for i := 0; i < len(n.children[child.typ]); i++ { 308 if n.children[child.typ][i].label == label && n.children[child.typ][i].tail == tail { 309 n.children[child.typ][i] = child 310 n.children[child.typ][i].label = label 311 n.children[child.typ][i].tail = tail 312 return 313 } 314 } 315 panic("chi: replacing missing child") 316} 317 318func (n *node) getEdge(ntyp nodeTyp, label, tail byte, prefix string) *node { 319 nds := n.children[ntyp] 320 for i := 0; i < len(nds); i++ { 321 if nds[i].label == label && nds[i].tail == tail { 322 if ntyp == ntRegexp && nds[i].prefix != prefix { 323 continue 324 } 325 return nds[i] 326 } 327 } 328 return nil 329} 330 331func (n *node) setEndpoint(method methodTyp, handler http.Handler, pattern string) { 332 // Set the handler for the method type on the node 333 if n.endpoints == nil { 334 n.endpoints = make(endpoints, 0) 335 } 336 337 paramKeys := patParamKeys(pattern) 338 339 if method&mSTUB == mSTUB { 340 n.endpoints.Value(mSTUB).handler = handler 341 } 342 if method&mALL == mALL { 343 h := n.endpoints.Value(mALL) 344 h.handler = handler 345 h.pattern = pattern 346 h.paramKeys = paramKeys 347 for _, m := range methodMap { 348 h := n.endpoints.Value(m) 349 h.handler = handler 350 h.pattern = pattern 351 h.paramKeys = paramKeys 352 } 353 } else { 354 h := n.endpoints.Value(method) 355 h.handler = handler 356 h.pattern = pattern 357 h.paramKeys = paramKeys 358 } 359} 360 361func (n *node) FindRoute(rctx *Context, method methodTyp, path string) (*node, endpoints, http.Handler) { 362 // Reset the context routing pattern and params 363 rctx.routePattern = "" 364 rctx.routeParams.Keys = rctx.routeParams.Keys[:0] 365 rctx.routeParams.Values = rctx.routeParams.Values[:0] 366 367 // Find the routing handlers for the path 368 rn := n.findRoute(rctx, method, path) 369 if rn == nil { 370 return nil, nil, nil 371 } 372 373 // Record the routing params in the request lifecycle 374 rctx.URLParams.Keys = append(rctx.URLParams.Keys, rctx.routeParams.Keys...) 375 rctx.URLParams.Values = append(rctx.URLParams.Values, rctx.routeParams.Values...) 376 377 // Record the routing pattern in the request lifecycle 378 if rn.endpoints[method].pattern != "" { 379 rctx.routePattern = rn.endpoints[method].pattern 380 rctx.RoutePatterns = append(rctx.RoutePatterns, rctx.routePattern) 381 } 382 383 return rn, rn.endpoints, rn.endpoints[method].handler 384} 385 386// Recursive edge traversal by checking all nodeTyp groups along the way. 387// It's like searching through a multi-dimensional radix trie. 388func (n *node) findRoute(rctx *Context, method methodTyp, path string) *node { 389 nn := n 390 search := path 391 392 for t, nds := range nn.children { 393 ntyp := nodeTyp(t) 394 if len(nds) == 0 { 395 continue 396 } 397 398 var xn *node 399 xsearch := search 400 401 var label byte 402 if search != "" { 403 label = search[0] 404 } 405 406 switch ntyp { 407 case ntStatic: 408 xn = nds.findEdge(label) 409 if xn == nil || !strings.HasPrefix(xsearch, xn.prefix) { 410 continue 411 } 412 xsearch = xsearch[len(xn.prefix):] 413 414 case ntParam, ntRegexp: 415 // short-circuit and return no matching route for empty param values 416 if xsearch == "" { 417 continue 418 } 419 420 // serially loop through each node grouped by the tail delimiter 421 for idx := 0; idx < len(nds); idx++ { 422 xn = nds[idx] 423 424 // label for param nodes is the delimiter byte 425 p := strings.IndexByte(xsearch, xn.tail) 426 427 if p < 0 { 428 if xn.tail == '/' { 429 p = len(xsearch) 430 } else { 431 continue 432 } 433 } 434 435 if ntyp == ntRegexp && xn.rex != nil { 436 if xn.rex.Match([]byte(xsearch[:p])) == false { 437 continue 438 } 439 } else if strings.IndexByte(xsearch[:p], '/') != -1 { 440 // avoid a match across path segments 441 continue 442 } 443 444 rctx.routeParams.Values = append(rctx.routeParams.Values, xsearch[:p]) 445 xsearch = xsearch[p:] 446 break 447 } 448 449 default: 450 // catch-all nodes 451 rctx.routeParams.Values = append(rctx.routeParams.Values, search) 452 xn = nds[0] 453 xsearch = "" 454 } 455 456 if xn == nil { 457 continue 458 } 459 460 // did we find it yet? 461 if len(xsearch) == 0 { 462 if xn.isLeaf() { 463 h, _ := xn.endpoints[method] 464 if h != nil && h.handler != nil { 465 rctx.routeParams.Keys = append(rctx.routeParams.Keys, h.paramKeys...) 466 return xn 467 } 468 469 // flag that the routing context found a route, but not a corresponding 470 // supported method 471 rctx.methodNotAllowed = true 472 } 473 } 474 475 // recursively find the next node.. 476 fin := xn.findRoute(rctx, method, xsearch) 477 if fin != nil { 478 return fin 479 } 480 481 // Did not find final handler, let's remove the param here if it was set 482 if xn.typ > ntStatic { 483 if len(rctx.routeParams.Values) > 0 { 484 rctx.routeParams.Values = rctx.routeParams.Values[:len(rctx.routeParams.Values)-1] 485 } 486 } 487 488 } 489 490 return nil 491} 492 493func (n *node) findEdge(ntyp nodeTyp, label byte) *node { 494 nds := n.children[ntyp] 495 num := len(nds) 496 idx := 0 497 498 switch ntyp { 499 case ntStatic, ntParam, ntRegexp: 500 i, j := 0, num-1 501 for i <= j { 502 idx = i + (j-i)/2 503 if label > nds[idx].label { 504 i = idx + 1 505 } else if label < nds[idx].label { 506 j = idx - 1 507 } else { 508 i = num // breaks cond 509 } 510 } 511 if nds[idx].label != label { 512 return nil 513 } 514 return nds[idx] 515 516 default: // catch all 517 return nds[idx] 518 } 519} 520 521func (n *node) isEmpty() bool { 522 for _, nds := range n.children { 523 if len(nds) > 0 { 524 return false 525 } 526 } 527 return true 528} 529 530func (n *node) isLeaf() bool { 531 return n.endpoints != nil 532} 533 534func (n *node) findPattern(pattern string) bool { 535 nn := n 536 for _, nds := range nn.children { 537 if len(nds) == 0 { 538 continue 539 } 540 541 n = nn.findEdge(nds[0].typ, pattern[0]) 542 if n == nil { 543 continue 544 } 545 546 var idx int 547 var xpattern string 548 549 switch n.typ { 550 case ntStatic: 551 idx = longestPrefix(pattern, n.prefix) 552 if idx < len(n.prefix) { 553 continue 554 } 555 556 case ntParam, ntRegexp: 557 idx = strings.IndexByte(pattern, '}') + 1 558 559 case ntCatchAll: 560 idx = longestPrefix(pattern, "*") 561 562 default: 563 panic("chi: unknown node type") 564 } 565 566 xpattern = pattern[idx:] 567 if len(xpattern) == 0 { 568 return true 569 } 570 571 return n.findPattern(xpattern) 572 } 573 return false 574} 575 576func (n *node) routes() []Route { 577 rts := []Route{} 578 579 n.walk(func(eps endpoints, subroutes Routes) bool { 580 if eps[mSTUB] != nil && eps[mSTUB].handler != nil && subroutes == nil { 581 return false 582 } 583 584 // Group methodHandlers by unique patterns 585 pats := make(map[string]endpoints, 0) 586 587 for mt, h := range eps { 588 if h.pattern == "" { 589 continue 590 } 591 p, ok := pats[h.pattern] 592 if !ok { 593 p = endpoints{} 594 pats[h.pattern] = p 595 } 596 p[mt] = h 597 } 598 599 for p, mh := range pats { 600 hs := make(map[string]http.Handler, 0) 601 if mh[mALL] != nil && mh[mALL].handler != nil { 602 hs["*"] = mh[mALL].handler 603 } 604 605 for mt, h := range mh { 606 if h.handler == nil { 607 continue 608 } 609 m := methodTypString(mt) 610 if m == "" { 611 continue 612 } 613 hs[m] = h.handler 614 } 615 616 rt := Route{p, hs, subroutes} 617 rts = append(rts, rt) 618 } 619 620 return false 621 }) 622 623 return rts 624} 625 626func (n *node) walk(fn func(eps endpoints, subroutes Routes) bool) bool { 627 // Visit the leaf values if any 628 if (n.endpoints != nil || n.subroutes != nil) && fn(n.endpoints, n.subroutes) { 629 return true 630 } 631 632 // Recurse on the children 633 for _, ns := range n.children { 634 for _, cn := range ns { 635 if cn.walk(fn) { 636 return true 637 } 638 } 639 } 640 return false 641} 642 643// patNextSegment returns the next segment details from a pattern: 644// node type, param key, regexp string, param tail byte, param starting index, param ending index 645func patNextSegment(pattern string) (nodeTyp, string, string, byte, int, int) { 646 ps := strings.Index(pattern, "{") 647 ws := strings.Index(pattern, "*") 648 649 if ps < 0 && ws < 0 { 650 return ntStatic, "", "", 0, 0, len(pattern) // we return the entire thing 651 } 652 653 // Sanity check 654 if ps >= 0 && ws >= 0 && ws < ps { 655 panic("chi: wildcard '*' must be the last pattern in a route, otherwise use a '{param}'") 656 } 657 658 var tail byte = '/' // Default endpoint tail to / byte 659 660 if ps >= 0 { 661 // Param/Regexp pattern is next 662 nt := ntParam 663 664 // Read to closing } taking into account opens and closes in curl count (cc) 665 cc := 0 666 pe := ps 667 for i, c := range pattern[ps:] { 668 if c == '{' { 669 cc++ 670 } else if c == '}' { 671 cc-- 672 if cc == 0 { 673 pe = ps + i 674 break 675 } 676 } 677 } 678 if pe == ps { 679 panic("chi: route param closing delimiter '}' is missing") 680 } 681 682 key := pattern[ps+1 : pe] 683 pe++ // set end to next position 684 685 if pe < len(pattern) { 686 tail = pattern[pe] 687 } 688 689 var rexpat string 690 if idx := strings.Index(key, ":"); idx >= 0 { 691 nt = ntRegexp 692 rexpat = key[idx+1:] 693 key = key[:idx] 694 } 695 696 if len(rexpat) > 0 { 697 if rexpat[0] != '^' { 698 rexpat = "^" + rexpat 699 } 700 if rexpat[len(rexpat)-1] != '$' { 701 rexpat = rexpat + "$" 702 } 703 } 704 705 return nt, key, rexpat, tail, ps, pe 706 } 707 708 // Wildcard pattern as finale 709 if ws < len(pattern)-1 { 710 panic("chi: wildcard '*' must be the last value in a route. trim trailing text or use a '{param}' instead") 711 } 712 return ntCatchAll, "*", "", 0, ws, len(pattern) 713} 714 715func patParamKeys(pattern string) []string { 716 pat := pattern 717 paramKeys := []string{} 718 for { 719 ptyp, paramKey, _, _, _, e := patNextSegment(pat) 720 if ptyp == ntStatic { 721 return paramKeys 722 } 723 for i := 0; i < len(paramKeys); i++ { 724 if paramKeys[i] == paramKey { 725 panic(fmt.Sprintf("chi: routing pattern '%s' contains duplicate param key, '%s'", pattern, paramKey)) 726 } 727 } 728 paramKeys = append(paramKeys, paramKey) 729 pat = pat[e:] 730 } 731} 732 733// longestPrefix finds the length of the shared prefix 734// of two strings 735func longestPrefix(k1, k2 string) int { 736 max := len(k1) 737 if l := len(k2); l < max { 738 max = l 739 } 740 var i int 741 for i = 0; i < max; i++ { 742 if k1[i] != k2[i] { 743 break 744 } 745 } 746 return i 747} 748 749func methodTypString(method methodTyp) string { 750 for s, t := range methodMap { 751 if method == t { 752 return s 753 } 754 } 755 return "" 756} 757 758type nodes []*node 759 760// Sort the list of nodes by label 761func (ns nodes) Sort() { sort.Sort(ns); ns.tailSort() } 762func (ns nodes) Len() int { return len(ns) } 763func (ns nodes) Swap(i, j int) { ns[i], ns[j] = ns[j], ns[i] } 764func (ns nodes) Less(i, j int) bool { return ns[i].label < ns[j].label } 765 766// tailSort pushes nodes with '/' as the tail to the end of the list for param nodes. 767// The list order determines the traversal order. 768func (ns nodes) tailSort() { 769 for i := len(ns) - 1; i >= 0; i-- { 770 if ns[i].typ > ntStatic && ns[i].tail == '/' { 771 ns.Swap(i, len(ns)-1) 772 return 773 } 774 } 775} 776 777func (ns nodes) findEdge(label byte) *node { 778 num := len(ns) 779 idx := 0 780 i, j := 0, num-1 781 for i <= j { 782 idx = i + (j-i)/2 783 if label > ns[idx].label { 784 i = idx + 1 785 } else if label < ns[idx].label { 786 j = idx - 1 787 } else { 788 i = num // breaks cond 789 } 790 } 791 if ns[idx].label != label { 792 return nil 793 } 794 return ns[idx] 795} 796 797// Route describes the details of a routing handler. 798type Route struct { 799 Pattern string 800 Handlers map[string]http.Handler 801 SubRoutes Routes 802} 803 804// WalkFunc is the type of the function called for each method and route visited by Walk. 805type WalkFunc func(method string, route string, handler http.Handler, middlewares ...func(http.Handler) http.Handler) error 806 807// Walk walks any router tree that implements Routes interface. 808func Walk(r Routes, walkFn WalkFunc) error { 809 return walk(r, walkFn, "") 810} 811 812func walk(r Routes, walkFn WalkFunc, parentRoute string, parentMw ...func(http.Handler) http.Handler) error { 813 for _, route := range r.Routes() { 814 mws := make([]func(http.Handler) http.Handler, len(parentMw)) 815 copy(mws, parentMw) 816 mws = append(mws, r.Middlewares()...) 817 818 if route.SubRoutes != nil { 819 if err := walk(route.SubRoutes, walkFn, parentRoute+route.Pattern, mws...); err != nil { 820 return err 821 } 822 continue 823 } 824 825 for method, handler := range route.Handlers { 826 if method == "*" { 827 // Ignore a "catchAll" method, since we pass down all the specific methods for each route. 828 continue 829 } 830 831 fullRoute := parentRoute + route.Pattern 832 833 if chain, ok := handler.(*ChainHandler); ok { 834 if err := walkFn(method, fullRoute, chain.Endpoint, append(mws, chain.Middlewares...)...); err != nil { 835 return err 836 } 837 } else { 838 if err := walkFn(method, fullRoute, handler, mws...); err != nil { 839 return err 840 } 841 } 842 } 843 } 844 845 return nil 846} 847