package http // Radix tree implementation below is a based on the original work by // Armon Dadgar in https://github.com/armon/go-radix/blob/master/radix.go // (MIT licensed). It's been heavily modified for use as a HTTP routing tree. // Copied from chi mux tree.go https://raw.githubusercontent.com/go-chi/chi/master/tree.go // Modified by Unistack LLC to support interface{} type handler and parameters in map[string]string import ( "fmt" "net/http" "regexp" "sort" "strconv" "strings" ) type methodTyp uint const ( mSTUB methodTyp = 1 << iota mCONNECT mDELETE mGET mHEAD mOPTIONS mPATCH mPOST mPUT mTRACE ) var mALL = mCONNECT | mDELETE | mGET | mHEAD | mOPTIONS | mPATCH | mPOST | mPUT | mTRACE var methodMap = map[string]methodTyp{ http.MethodConnect: mCONNECT, http.MethodDelete: mDELETE, http.MethodGet: mGET, http.MethodHead: mHEAD, http.MethodOptions: mOPTIONS, http.MethodPatch: mPATCH, http.MethodPost: mPOST, http.MethodPut: mPUT, http.MethodTrace: mTRACE, } // RegisterMethod adds support for custom HTTP method handlers, available // via Router#Method and Router#MethodFunc func RegisterMethod(method string) error { if method == "" { return nil } method = strings.ToUpper(method) if _, ok := methodMap[method]; ok { return nil } n := len(methodMap) if n > strconv.IntSize-2 { return fmt.Errorf("max number of methods reached (%d)", strconv.IntSize) } mt := methodTyp(2 << n) methodMap[method] = mt mALL |= mt return nil } type nodeTyp uint8 const ( ntStatic nodeTyp = iota // /home ntRegexp // /{id:[0-9]+} ntParam // /{user} ntCatchAll // /api/v1/* ) func NewTrie() *Node { return &Node{} } type Trie = Node type Node struct { // regexp matcher for regexp nodes rex *regexp.Regexp // HTTP handler endpoints on the leaf node endpoints endpoints // prefix is the common prefix we ignore prefix string // child nodes should be stored in-order for iteration, // in groups of the node type. children [ntCatchAll + 1]nodes // first byte of the child prefix tail byte // node type: static, regexp, param, catchAll typ nodeTyp // first byte of the prefix label byte } // endpoints is a mapping of http method constants to handlers // for a given route. type endpoints map[methodTyp]*endpoint type endpoint struct { // endpoint handler handler interface{} // pattern is the routing pattern for handler nodes pattern string // parameters keys recorded on handler nodes paramKeys []string } func (s endpoints) Value(method methodTyp) *endpoint { mh, ok := s[method] if !ok { mh = &endpoint{} s[method] = mh } return mh } func (n *Node) Insert(methods []string, pattern string, handler interface{}) error { var err error for _, method := range methods { if err = n.insert(methodMap[method], pattern, handler); err != nil { return err } } return nil } func (n *Node) insert(method methodTyp, pattern string, handler interface{}) error { var parent *Node search := pattern for { // Handle key exhaustion if len(search) == 0 { // Insert or update the node's leaf handler return n.setEndpoint(method, handler, pattern) } // We're going to be searching for a wild node next, // in this case, we need to get the tail label := search[0] var segTail byte var segEndIdx int var segTyp nodeTyp var segRexpat string var err error if label == '{' || label == '*' { segTyp, _, segRexpat, segTail, _, segEndIdx, err = patNextSegment(search) } if err != nil { return err } var prefix string if segTyp == ntRegexp { prefix = segRexpat } // Look for the edge to attach to parent = n n = n.getEdge(segTyp, label, segTail, prefix) // No edge, create one if n == nil { child := &Node{typ: ntStatic, label: label, tail: segTail, prefix: search} var hn *Node hn, err = parent.addChild(child, search) if err != nil { return err } return hn.setEndpoint(method, handler, pattern) } // Found an edge to match the pattern if n.typ > ntStatic { // We found a param node, trim the param from the search path and continue. // This param/wild pattern segment would already be on the tree from a previous // call to addChild when creating a new node. search = search[segEndIdx:] continue } // Static nodes fall below here. // Determine longest prefix of the search key on match. commonPrefix := longestPrefix(search, n.prefix) if commonPrefix == len(n.prefix) { // the common prefix is as long as the current node's prefix we're attempting to insert. // keep the search going. search = search[commonPrefix:] continue } // Split the node child := &Node{ typ: ntStatic, prefix: search[:commonPrefix], } if err = parent.replaceChild(search[0], segTail, child); err != nil { return err } // Restore the existing node n.label = n.prefix[commonPrefix] n.prefix = n.prefix[commonPrefix:] if _, err = child.addChild(n, n.prefix); err != nil { return err } // If the new key is a subset, set the method/handler on this node and finish. search = search[commonPrefix:] if len(search) == 0 { return child.setEndpoint(method, handler, pattern) } // Create a new edge for the node subchild := &Node{ typ: ntStatic, label: search[0], prefix: search, } var hn *Node hn, err = child.addChild(subchild, search) if err != nil { return err } return hn.setEndpoint(method, handler, pattern) } } // addChild appends the new `child` node to the tree using the `pattern` as the trie key. // For a URL router like chi's, we split the static, param, regexp and wildcard segments // into different nodes. In addition, addChild will recursively call itself until every // pattern segment is added to the url pattern tree as individual nodes, depending on type. func (n *Node) addChild(child *Node, prefix string) (*Node, error) { search := prefix // handler leaf node added to the tree is the child. // this may be overridden later down the flow hn := child // Parse next segment segTyp, _, segRexpat, segTail, segStartIdx, segEndIdx, err := patNextSegment(search) if err != nil { return nil, err } // Add child depending on next up segment switch segTyp { case ntStatic: // Search prefix is all static (that is, has no params in path) // noop default: // Search prefix contains a param, regexp or wildcard if segTyp == ntRegexp { rex, err := regexp.Compile(segRexpat) if err != nil { return nil, fmt.Errorf("invalid regexp pattern '%s' in route param", segRexpat) } child.prefix = segRexpat child.rex = rex } switch { case segStartIdx == 0: // Route starts with a param child.typ = segTyp if segTyp == ntCatchAll { segStartIdx = -1 } else { segStartIdx = segEndIdx } if segStartIdx < 0 { segStartIdx = len(search) } child.tail = segTail // for params, we set the tail if segStartIdx != len(search) { // add static edge for the remaining part, split the end. // its not possible to have adjacent param nodes, so its certainly // going to be a static node next. search = search[segStartIdx:] // advance search position nn := &Node{ typ: ntStatic, label: search[0], prefix: search, } var err error hn, err = child.addChild(nn, search) if err != nil { return nil, err } } case segStartIdx > 0: // Route has some param // starts with a static segment child.typ = ntStatic child.prefix = search[:segStartIdx] child.rex = nil // add the param edge node search = search[segStartIdx:] nn := &Node{ typ: segTyp, label: search[0], tail: segTail, } var err error hn, err = child.addChild(nn, search) if err != nil { return nil, err } } } n.children[child.typ] = append(n.children[child.typ], child) n.children[child.typ].Sort() return hn, nil } func (n *Node) replaceChild(label, tail byte, child *Node) error { for i := 0; i < len(n.children[child.typ]); i++ { if n.children[child.typ][i].label == label && n.children[child.typ][i].tail == tail { n.children[child.typ][i] = child n.children[child.typ][i].label = label n.children[child.typ][i].tail = tail return nil } } return fmt.Errorf("replacing missing child") } func (n *Node) getEdge(ntyp nodeTyp, label, tail byte, prefix string) *Node { nds := n.children[ntyp] for i := 0; i < len(nds); i++ { if nds[i].label == label && nds[i].tail == tail { if ntyp == ntRegexp && nds[i].prefix != prefix { continue } return nds[i] } } return nil } func (n *Node) setEndpoint(method methodTyp, handler interface{}, pattern string) error { // Set the handler for the method type on the node if n.endpoints == nil { n.endpoints = make(endpoints) } paramKeys, err := patParamKeys(pattern) if err != nil { return err } if method&mSTUB == mSTUB { n.endpoints.Value(mSTUB).handler = handler } if method&mALL == mALL { h := n.endpoints.Value(mALL) h.handler = handler h.pattern = pattern h.paramKeys = paramKeys for _, m := range methodMap { h := n.endpoints.Value(m) h.handler = handler h.pattern = pattern h.paramKeys = paramKeys } } else { h := n.endpoints.Value(method) h.handler = handler h.pattern = pattern h.paramKeys = paramKeys } return nil } func (n *Node) Search(method string, path string) (interface{}, map[string]string, bool) { params := &routeParams{} // Find the routing handlers for the path rn := n.findRoute(params, methodMap[method], path) if rn == nil { return nil, nil, false } ep, ok := rn.endpoints[methodMap[method]] if !ok { return nil, nil, false } eparams := make(map[string]string, len(params.keys)) for idx, key := range params.keys { eparams[key] = params.vals[idx] } return ep.handler, eparams, true } type routeParams struct { keys []string vals []string } // Recursive edge traversal by checking all nodeTyp groups along the way. // It's like searching through a multi-dimensional radix trie. func (n *Node) findRoute(params *routeParams, method methodTyp, path string) *Node { nn := n search := path for t, nds := range nn.children { ntyp := nodeTyp(t) if len(nds) == 0 { continue } var xn *Node xsearch := search var label byte if search != "" { label = search[0] } switch ntyp { case ntStatic: xn = nds.findEdge(label) if xn == nil || !strings.HasPrefix(xsearch, xn.prefix) { continue } xsearch = xsearch[len(xn.prefix):] case ntParam, ntRegexp: // short-circuit and return no matching route for empty param values if xsearch == "" { continue } // serially loop through each node grouped by the tail delimiter for idx := 0; idx < len(nds); idx++ { xn = nds[idx] // label for param nodes is the delimiter byte p := strings.IndexByte(xsearch, xn.tail) if p < 0 { if xn.tail == '/' { p = len(xsearch) } else { continue } } else if ntyp == ntRegexp && p == 0 { continue } if ntyp == ntRegexp && xn.rex != nil { if !xn.rex.MatchString(xsearch[:p]) { continue } } else if strings.IndexByte(xsearch[:p], '/') != -1 { // avoid a match across path segments continue } prevlen := len(params.vals) params.vals = append(params.vals, xsearch[:p]) xsearch = xsearch[p:] if len(xsearch) == 0 { if xn.isLeaf() { h := xn.endpoints[method] if h != nil && h.handler != nil { params.keys = append(params.keys, h.paramKeys...) return xn } } } // recursively find the next node on this branch fin := xn.findRoute(params, method, xsearch) if fin != nil { return fin } // not found on this branch, reset vars params.vals = params.vals[:prevlen] xsearch = search } params.vals = append(params.vals, "") default: // catch-all nodes params.vals = append(params.vals, search) xn = nds[0] xsearch = "" } if xn == nil { continue } // did we find it yet? if len(xsearch) == 0 { if xn.isLeaf() { h := xn.endpoints[method] if h != nil && h.handler != nil { params.keys = append(params.keys, h.paramKeys...) return xn } } } // recursively find the next node.. fin := xn.findRoute(params, method, xsearch) if fin != nil { return fin } // Did not find final handler, let's remove the param here if it was set if xn.typ > ntStatic { if len(params.vals) > 0 { params.vals = params.vals[:len(params.vals)-1] } } } return nil } func (n *Node) isLeaf() bool { return n.endpoints != nil } // patNextSegment returns the next segment details from a pattern: // node type, param key, regexp string, param tail byte, param starting index, param ending index func patNextSegment(pattern string) (nodeTyp, string, string, byte, int, int, error) { ps := strings.Index(pattern, "{") ws := strings.Index(pattern, "*") if ps < 0 && ws < 0 { return ntStatic, "", "", 0, 0, len(pattern), nil // we return the entire thing } // Sanity check if ps >= 0 && ws >= 0 && ws < ps { return ntStatic, "", "", 0, 0, 0, fmt.Errorf("wildcard '*' must be the last pattern in a route, otherwise use a '{param}'") } var tail byte = '/' // Default endpoint tail to / byte if ps < 0 { // Wildcard pattern as finale if ws < len(pattern)-1 { return ntStatic, "", "", 0, 0, 0, fmt.Errorf("wildcard '*' must be the last value in a route. trim trailing text or use a '{param}' instead") } return ntCatchAll, "*", "", 0, ws, len(pattern), nil } // Param/Regexp pattern is next nt := ntParam // Read to closing } taking into account opens and closes in curl count (cc) cc := 0 pe := ps for i, c := range pattern[ps:] { if c == '{' { cc++ } else if c == '}' { cc-- if cc == 0 { pe = ps + i break } } } if pe == ps { return ntStatic, "", "", 0, 0, 0, fmt.Errorf("route param closing delimiter '}' is missing") } key := pattern[ps+1 : pe] pe++ // set end to next position if pe < len(pattern) { tail = pattern[pe] } var rexpat string if idx := strings.Index(key, ":"); idx >= 0 { nt = ntRegexp rexpat = key[idx+1:] key = key[:idx] } if len(rexpat) > 0 { if rexpat[0] != '^' { rexpat = "^" + rexpat } if rexpat[len(rexpat)-1] != '$' { rexpat += "$" } } return nt, key, rexpat, tail, ps, pe, nil } func patParamKeys(pattern string) ([]string, error) { pat := pattern paramKeys := []string{} for { ptyp, paramKey, _, _, _, e, err := patNextSegment(pat) if err != nil { return nil, err } if ptyp == ntStatic { return paramKeys, nil } for i := 0; i < len(paramKeys); i++ { if paramKeys[i] == paramKey { return nil, fmt.Errorf("routing pattern '%s' contains duplicate param key, '%s'", pattern, paramKey) } } paramKeys = append(paramKeys, paramKey) pat = pat[e:] } } // longestPrefix finds the length of the shared prefix // of two strings func longestPrefix(k1, k2 string) int { max := len(k1) if l := len(k2); l < max { max = l } var i int for i = 0; i < max; i++ { if k1[i] != k2[i] { break } } return i } type nodes []*Node // Sort the list of nodes by label func (ns nodes) Sort() { sort.Sort(ns); ns.tailSort() } func (ns nodes) Len() int { return len(ns) } func (ns nodes) Swap(i, j int) { ns[i], ns[j] = ns[j], ns[i] } func (ns nodes) Less(i, j int) bool { return ns[i].label < ns[j].label } // tailSort pushes nodes with '/' as the tail to the end of the list for param nodes. // The list order determines the traversal order. func (ns nodes) tailSort() { for i := len(ns) - 1; i >= 0; i-- { if ns[i].typ > ntStatic && ns[i].tail == '/' { ns.Swap(i, len(ns)-1) return } } } func (ns nodes) findEdge(label byte) *Node { num := len(ns) idx := 0 i, j := 0, num-1 for i <= j { idx = i + (j-i)/2 if label > ns[idx].label { i = idx + 1 } else if label < ns[idx].label { j = idx - 1 } else { i = num // breaks cond } } if ns[idx].label != label { return nil } return ns[idx] }