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// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: © 2015 LabStack LLC and Echo contributors
package echo
import (
"bytes"
"fmt"
"net/http"
)
// Router is the registry of all registered routes for an `Echo` instance for
// request matching and URL path parameter parsing.
type Router struct {
tree *node
routes map[string]*Route
echo *Echo
}
type node struct {
kind kind
label byte
prefix string
parent *node
staticChildren children
originalPath string
methods *routeMethods
paramChild *node
anyChild *node
paramsCount int
// isLeaf indicates that node does not have child routes
isLeaf bool
// isHandler indicates that node has at least one handler registered to it
isHandler bool
// notFoundHandler is handler registered with RouteNotFound method and is executed for 404 cases
notFoundHandler *routeMethod
}
type kind uint8
type children []*node
type routeMethod struct {
ppath string
pnames []string
handler HandlerFunc
}
type routeMethods struct {
connect *routeMethod
delete *routeMethod
get *routeMethod
head *routeMethod
options *routeMethod
patch *routeMethod
post *routeMethod
propfind *routeMethod
put *routeMethod
trace *routeMethod
report *routeMethod
anyOther map[string]*routeMethod
allowHeader string
}
const (
staticKind kind = iota
paramKind
anyKind
paramLabel = byte(':')
anyLabel = byte('*')
)
func (m *routeMethods) isHandler() bool {
return m.connect != nil ||
m.delete != nil ||
m.get != nil ||
m.head != nil ||
m.options != nil ||
m.patch != nil ||
m.post != nil ||
m.propfind != nil ||
m.put != nil ||
m.trace != nil ||
m.report != nil ||
len(m.anyOther) != 0
// RouteNotFound/404 is not considered as a handler
}
func (m *routeMethods) updateAllowHeader() {
buf := new(bytes.Buffer)
buf.WriteString(http.MethodOptions)
if m.connect != nil {
buf.WriteString(", ")
buf.WriteString(http.MethodConnect)
}
if m.delete != nil {
buf.WriteString(", ")
buf.WriteString(http.MethodDelete)
}
if m.get != nil {
buf.WriteString(", ")
buf.WriteString(http.MethodGet)
}
if m.head != nil {
buf.WriteString(", ")
buf.WriteString(http.MethodHead)
}
if m.patch != nil {
buf.WriteString(", ")
buf.WriteString(http.MethodPatch)
}
if m.post != nil {
buf.WriteString(", ")
buf.WriteString(http.MethodPost)
}
if m.propfind != nil {
buf.WriteString(", PROPFIND")
}
if m.put != nil {
buf.WriteString(", ")
buf.WriteString(http.MethodPut)
}
if m.trace != nil {
buf.WriteString(", ")
buf.WriteString(http.MethodTrace)
}
if m.report != nil {
buf.WriteString(", REPORT")
}
for method := range m.anyOther { // for simplicity, we use map and therefore order is not deterministic here
buf.WriteString(", ")
buf.WriteString(method)
}
m.allowHeader = buf.String()
}
// NewRouter returns a new Router instance.
func NewRouter(e *Echo) *Router {
return &Router{
tree: &node{
methods: new(routeMethods),
},
routes: map[string]*Route{},
echo: e,
}
}
// Routes returns the registered routes.
func (r *Router) Routes() []*Route {
routes := make([]*Route, 0, len(r.routes))
for _, v := range r.routes {
routes = append(routes, v)
}
return routes
}
// Reverse generates a URL from route name and provided parameters.
func (r *Router) Reverse(name string, params ...interface{}) string {
uri := new(bytes.Buffer)
ln := len(params)
n := 0
for _, route := range r.routes {
if route.Name == name {
for i, l := 0, len(route.Path); i < l; i++ {
hasBackslash := route.Path[i] == '\\'
if hasBackslash && i+1 < l && route.Path[i+1] == ':' {
i++ // backslash before colon escapes that colon. in that case skip backslash
}
if n < ln && (route.Path[i] == '*' || (!hasBackslash && route.Path[i] == ':')) {
// in case of `*` wildcard or `:` (unescaped colon) param we replace everything till next slash or end of path
for ; i < l && route.Path[i] != '/'; i++ {
}
uri.WriteString(fmt.Sprintf("%v", params[n]))
n++
}
if i < l {
uri.WriteByte(route.Path[i])
}
}
break
}
}
return uri.String()
}
func normalizePathSlash(path string) string {
if path == "" {
path = "/"
} else if path[0] != '/' {
path = "/" + path
}
return path
}
func (r *Router) add(method, path, name string, h HandlerFunc) *Route {
path = normalizePathSlash(path)
r.insert(method, path, h)
route := &Route{
Method: method,
Path: path,
Name: name,
}
r.routes[method+path] = route
return route
}
// Add registers a new route for method and path with matching handler.
func (r *Router) Add(method, path string, h HandlerFunc) {
r.insert(method, normalizePathSlash(path), h)
}
func (r *Router) insert(method, path string, h HandlerFunc) {
path = normalizePathSlash(path)
pnames := []string{} // Param names
ppath := path // Pristine path
if h == nil && r.echo.Logger != nil {
// FIXME: in future we should return error
r.echo.Logger.Errorf("Adding route without handler function: %v:%v", method, path)
}
for i, lcpIndex := 0, len(path); i < lcpIndex; i++ {
if path[i] == ':' {
if i > 0 && path[i-1] == '\\' {
path = path[:i-1] + path[i:]
i--
lcpIndex--
continue
}
j := i + 1
r.insertNode(method, path[:i], staticKind, routeMethod{})
for ; i < lcpIndex && path[i] != '/'; i++ {
}
pnames = append(pnames, path[j:i])
path = path[:j] + path[i:]
i, lcpIndex = j, len(path)
if i == lcpIndex {
// path node is last fragment of route path. ie. `/users/:id`
r.insertNode(method, path[:i], paramKind, routeMethod{ppath, pnames, h})
} else {
r.insertNode(method, path[:i], paramKind, routeMethod{})
}
} else if path[i] == '*' {
r.insertNode(method, path[:i], staticKind, routeMethod{})
pnames = append(pnames, "*")
r.insertNode(method, path[:i+1], anyKind, routeMethod{ppath, pnames, h})
}
}
r.insertNode(method, path, staticKind, routeMethod{ppath, pnames, h})
}
func (r *Router) insertNode(method, path string, t kind, rm routeMethod) {
// Adjust max param
paramLen := len(rm.pnames)
if *r.echo.maxParam < paramLen {
*r.echo.maxParam = paramLen
}
currentNode := r.tree // Current node as root
if currentNode == nil {
panic("echo: invalid method")
}
search := path
for {
searchLen := len(search)
prefixLen := len(currentNode.prefix)
lcpLen := 0
// LCP - Longest Common Prefix (https://en.wikipedia.org/wiki/LCP_array)
max := prefixLen
if searchLen < max {
max = searchLen
}
for ; lcpLen < max && search[lcpLen] == currentNode.prefix[lcpLen]; lcpLen++ {
}
if lcpLen == 0 {
// At root node
currentNode.label = search[0]
currentNode.prefix = search
if rm.handler != nil {
currentNode.kind = t
currentNode.addMethod(method, &rm)
currentNode.paramsCount = len(rm.pnames)
currentNode.originalPath = rm.ppath
}
currentNode.isLeaf = currentNode.staticChildren == nil && currentNode.paramChild == nil && currentNode.anyChild == nil
} else if lcpLen < prefixLen {
// Split node into two before we insert new node.
// This happens when we are inserting path that is submatch of any existing inserted paths.
// For example, we have node `/test` and now are about to insert `/te/*`. In that case
// 1. overlapping part is `/te` that is used as parent node
// 2. `st` is part from existing node that is not matching - it gets its own node (child to `/te`)
// 3. `/*` is the new part we are about to insert (child to `/te`)
n := newNode(
currentNode.kind,
currentNode.prefix[lcpLen:],
currentNode,
currentNode.staticChildren,
currentNode.originalPath,
currentNode.methods,
currentNode.paramsCount,
currentNode.paramChild,
currentNode.anyChild,
currentNode.notFoundHandler,
)
// Update parent path for all children to new node
for _, child := range currentNode.staticChildren {
child.parent = n
}
if currentNode.paramChild != nil {
currentNode.paramChild.parent = n
}
if currentNode.anyChild != nil {
currentNode.anyChild.parent = n
}
// Reset parent node
currentNode.kind = staticKind
currentNode.label = currentNode.prefix[0]
currentNode.prefix = currentNode.prefix[:lcpLen]
currentNode.staticChildren = nil
currentNode.originalPath = ""
currentNode.methods = new(routeMethods)
currentNode.paramsCount = 0
currentNode.paramChild = nil
currentNode.anyChild = nil
currentNode.isLeaf = false
currentNode.isHandler = false
currentNode.notFoundHandler = nil
// Only Static children could reach here
currentNode.addStaticChild(n)
if lcpLen == searchLen {
// At parent node
currentNode.kind = t
if rm.handler != nil {
currentNode.addMethod(method, &rm)
currentNode.paramsCount = len(rm.pnames)
currentNode.originalPath = rm.ppath
}
} else {
// Create child node
n = newNode(t, search[lcpLen:], currentNode, nil, "", new(routeMethods), 0, nil, nil, nil)
if rm.handler != nil {
n.addMethod(method, &rm)
n.paramsCount = len(rm.pnames)
n.originalPath = rm.ppath
}
// Only Static children could reach here
currentNode.addStaticChild(n)
}
currentNode.isLeaf = currentNode.staticChildren == nil && currentNode.paramChild == nil && currentNode.anyChild == nil
} else if lcpLen < searchLen {
search = search[lcpLen:]
c := currentNode.findChildWithLabel(search[0])
if c != nil {
// Go deeper
currentNode = c
continue
}
// Create child node
n := newNode(t, search, currentNode, nil, rm.ppath, new(routeMethods), 0, nil, nil, nil)
if rm.handler != nil {
n.addMethod(method, &rm)
n.paramsCount = len(rm.pnames)
}
switch t {
case staticKind:
currentNode.addStaticChild(n)
case paramKind:
currentNode.paramChild = n
case anyKind:
currentNode.anyChild = n
}
currentNode.isLeaf = currentNode.staticChildren == nil && currentNode.paramChild == nil && currentNode.anyChild == nil
} else {
// Node already exists
if rm.handler != nil {
currentNode.addMethod(method, &rm)
currentNode.paramsCount = len(rm.pnames)
currentNode.originalPath = rm.ppath
}
}
return
}
}
func newNode(
t kind,
pre string,
p *node,
sc children,
originalPath string,
methods *routeMethods,
paramsCount int,
paramChildren,
anyChildren *node,
notFoundHandler *routeMethod,
) *node {
return &node{
kind: t,
label: pre[0],
prefix: pre,
parent: p,
staticChildren: sc,
originalPath: originalPath,
methods: methods,
paramsCount: paramsCount,
paramChild: paramChildren,
anyChild: anyChildren,
isLeaf: sc == nil && paramChildren == nil && anyChildren == nil,
isHandler: methods.isHandler(),
notFoundHandler: notFoundHandler,
}
}
func (n *node) addStaticChild(c *node) {
n.staticChildren = append(n.staticChildren, c)
}
func (n *node) findStaticChild(l byte) *node {
for _, c := range n.staticChildren {
if c.label == l {
return c
}
}
return nil
}
func (n *node) findChildWithLabel(l byte) *node {
if c := n.findStaticChild(l); c != nil {
return c
}
if l == paramLabel {
return n.paramChild
}
if l == anyLabel {
return n.anyChild
}
return nil
}
func (n *node) addMethod(method string, h *routeMethod) {
switch method {
case http.MethodConnect:
n.methods.connect = h
case http.MethodDelete:
n.methods.delete = h
case http.MethodGet:
n.methods.get = h
case http.MethodHead:
n.methods.head = h
case http.MethodOptions:
n.methods.options = h
case http.MethodPatch:
n.methods.patch = h
case http.MethodPost:
n.methods.post = h
case PROPFIND:
n.methods.propfind = h
case http.MethodPut:
n.methods.put = h
case http.MethodTrace:
n.methods.trace = h
case REPORT:
n.methods.report = h
case RouteNotFound:
n.notFoundHandler = h
return // RouteNotFound/404 is not considered as a handler so no further logic needs to be executed
default:
if n.methods.anyOther == nil {
n.methods.anyOther = make(map[string]*routeMethod)
}
if h.handler == nil {
delete(n.methods.anyOther, method)
} else {
n.methods.anyOther[method] = h
}
}
n.methods.updateAllowHeader()
n.isHandler = true
}
func (n *node) findMethod(method string) *routeMethod {
switch method {
case http.MethodConnect:
return n.methods.connect
case http.MethodDelete:
return n.methods.delete
case http.MethodGet:
return n.methods.get
case http.MethodHead:
return n.methods.head
case http.MethodOptions:
return n.methods.options
case http.MethodPatch:
return n.methods.patch
case http.MethodPost:
return n.methods.post
case PROPFIND:
return n.methods.propfind
case http.MethodPut:
return n.methods.put
case http.MethodTrace:
return n.methods.trace
case REPORT:
return n.methods.report
default: // RouteNotFound/404 is not considered as a handler
return n.methods.anyOther[method]
}
}
func optionsMethodHandler(allowMethods string) func(c Context) error {
return func(c Context) error {
// Note: we are not handling most of the CORS headers here. CORS is handled by CORS middleware
// 'OPTIONS' method RFC: https://httpwg.org/specs/rfc7231.html#OPTIONS
// 'Allow' header RFC: https://datatracker.ietf.org/doc/html/rfc7231#section-7.4.1
c.Response().Header().Add(HeaderAllow, allowMethods)
return c.NoContent(http.StatusNoContent)
}
}
// Find lookup a handler registered for method and path. It also parses URL for path
// parameters and load them into context.
//
// For performance:
//
// - Get context from `Echo#AcquireContext()`
// - Reset it `Context#Reset()`
// - Return it `Echo#ReleaseContext()`.
func (r *Router) Find(method, path string, c Context) {
ctx := c.(*context)
currentNode := r.tree // Current node as root
var (
previousBestMatchNode *node
matchedRouteMethod *routeMethod
// search stores the remaining path to check for match. By each iteration we move from start of path to end of the path
// and search value gets shorter and shorter.
search = path
searchIndex = 0
paramIndex int // Param counter
paramValues = ctx.pvalues // Use the internal slice so the interface can keep the illusion of a dynamic slice
)
// Backtracking is needed when a dead end (leaf node) is reached in the router tree.
// To backtrack the current node will be changed to the parent node and the next kind for the
// router logic will be returned based on fromKind or kind of the dead end node (static > param > any).
// For example if there is no static node match we should check parent next sibling by kind (param).
// Backtracking itself does not check if there is a next sibling, this is done by the router logic.
backtrackToNextNodeKind := func(fromKind kind) (nextNodeKind kind, valid bool) {
previous := currentNode
currentNode = previous.parent
valid = currentNode != nil
// Next node type by priority
if previous.kind == anyKind {
nextNodeKind = staticKind
} else {
nextNodeKind = previous.kind + 1
}
if fromKind == staticKind {
// when backtracking is done from static kind block we did not change search so nothing to restore
return
}
// restore search to value it was before we move to current node we are backtracking from.
if previous.kind == staticKind {
searchIndex -= len(previous.prefix)
} else {
paramIndex--
// for param/any node.prefix value is always `:` so we can not deduce searchIndex from that and must use pValue
// for that index as it would also contain part of path we cut off before moving into node we are backtracking from
searchIndex -= len(paramValues[paramIndex])
paramValues[paramIndex] = ""
}
search = path[searchIndex:]
return
}
// Router tree is implemented by longest common prefix array (LCP array) https://en.wikipedia.org/wiki/LCP_array
// Tree search is implemented as for loop where one loop iteration is divided into 3 separate blocks
// Each of these blocks checks specific kind of node (static/param/any). Order of blocks reflex their priority in routing.
// Search order/priority is: static > param > any.
//
// Note: backtracking in tree is implemented by replacing/switching currentNode to previous node
// and hoping to (goto statement) next block by priority to check if it is the match.
for {
prefixLen := 0 // Prefix length
lcpLen := 0 // LCP (longest common prefix) length
if currentNode.kind == staticKind {
searchLen := len(search)
prefixLen = len(currentNode.prefix)
// LCP - Longest Common Prefix (https://en.wikipedia.org/wiki/LCP_array)
max := prefixLen
if searchLen < max {
max = searchLen
}
for ; lcpLen < max && search[lcpLen] == currentNode.prefix[lcpLen]; lcpLen++ {
}
}
if lcpLen != prefixLen {
// No matching prefix, let's backtrack to the first possible alternative node of the decision path
nk, ok := backtrackToNextNodeKind(staticKind)
if !ok {
return // No other possibilities on the decision path, handler will be whatever context is reset to.
} else if nk == paramKind {
goto Param
// NOTE: this case (backtracking from static node to previous any node) can not happen by current any matching logic. Any node is end of search currently
//} else if nk == anyKind {
// goto Any
} else {
// Not found (this should never be possible for static node we are looking currently)
break
}
}
// The full prefix has matched, remove the prefix from the remaining search
search = search[lcpLen:]
searchIndex = searchIndex + lcpLen
// Finish routing if is no request path remaining to search
if search == "" {
// in case of node that is handler we have exact method type match or something for 405 to use
if currentNode.isHandler {
// check if current node has handler registered for http method we are looking for. we store currentNode as
// best matching in case we do no find no more routes matching this path+method
if previousBestMatchNode == nil {
previousBestMatchNode = currentNode
}
if h := currentNode.findMethod(method); h != nil {
matchedRouteMethod = h
break
}
} else if currentNode.notFoundHandler != nil {
matchedRouteMethod = currentNode.notFoundHandler
break
}
}
// Static node
if search != "" {
if child := currentNode.findStaticChild(search[0]); child != nil {
currentNode = child
continue
}
}
Param:
// Param node
if child := currentNode.paramChild; search != "" && child != nil {
currentNode = child
i := 0
l := len(search)
if currentNode.isLeaf {
// when param node does not have any children (path param is last piece of route path) then param node should
// act similarly to any node - consider all remaining search as match
i = l
} else {
for ; i < l && search[i] != '/'; i++ {
}
}
paramValues[paramIndex] = search[:i]
paramIndex++
search = search[i:]
searchIndex = searchIndex + i
continue
}
Any:
// Any node
if child := currentNode.anyChild; child != nil {
// If any node is found, use remaining path for paramValues
currentNode = child
paramValues[currentNode.paramsCount-1] = search
// update indexes/search in case we need to backtrack when no handler match is found
paramIndex++
searchIndex += +len(search)
search = ""
if h := currentNode.findMethod(method); h != nil {
matchedRouteMethod = h
break
}
// we store currentNode as best matching in case we do not find more routes matching this path+method. Needed for 405
if previousBestMatchNode == nil {
previousBestMatchNode = currentNode
}
if currentNode.notFoundHandler != nil {
matchedRouteMethod = currentNode.notFoundHandler
break
}
}
// Let's backtrack to the first possible alternative node of the decision path
nk, ok := backtrackToNextNodeKind(anyKind)
if !ok {
break // No other possibilities on the decision path
} else if nk == paramKind {
goto Param
} else if nk == anyKind {
goto Any
} else {
// Not found
break
}
}
if currentNode == nil && previousBestMatchNode == nil {
return // nothing matched at all
}
// matchedHandler could be method+path handler that we matched or notFoundHandler from node with matching path
// user provided not found (404) handler has priority over generic method not found (405) handler or global 404 handler
var rPath string
var rPNames []string
if matchedRouteMethod != nil {
rPath = matchedRouteMethod.ppath
rPNames = matchedRouteMethod.pnames
ctx.handler = matchedRouteMethod.handler
} else {
// use previous match as basis. although we have no matching handler we have path match.
// so we can send http.StatusMethodNotAllowed (405) instead of http.StatusNotFound (404)
currentNode = previousBestMatchNode
rPath = currentNode.originalPath
rPNames = nil // no params here
ctx.handler = NotFoundHandler
if currentNode.notFoundHandler != nil {
rPath = currentNode.notFoundHandler.ppath
rPNames = currentNode.notFoundHandler.pnames
ctx.handler = currentNode.notFoundHandler.handler
} else if currentNode.isHandler {
ctx.Set(ContextKeyHeaderAllow, currentNode.methods.allowHeader)
ctx.handler = MethodNotAllowedHandler
if method == http.MethodOptions {
ctx.handler = optionsMethodHandler(currentNode.methods.allowHeader)
}
}
}
ctx.path = rPath
ctx.pnames = rPNames
}
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