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router.go
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router.go
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// Forked from https://github.com/julienschmidt/httprouter
//
// Copyright 2013 Julien Schmidt. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be found
// in the LICENSE file.
package httprouter
import (
"context"
"net/http"
"strings"
)
// Param is a single URL parameter, consisting of a key and a value.
type Param struct {
Key string
Value string
}
// Params is a Param-slice, as returned by the router.
// The slice is ordered, the first URL parameter is also the first slice value.
// It is therefore safe to read values by the index.
type Params []Param
// ByName returns the value of the first Param which key matches the given name.
// If no matching Param is found, an empty string is returned.
func (ps Params) ByName(name string) string {
for _, p := range ps {
if p.Key == name {
return p.Value
}
}
return ""
}
var catchAllParam = "$catchAllParam"
// CatchAll retrieves the remaining path matched by the catch all, if
// the catch all was not named.
func (ps Params) CatchAll() string {
return ps.ByName(catchAllParam)
}
type paramsKey struct{}
// ParamsKey is the request context key under which URL params are stored.
var ParamsKey = paramsKey{}
// ParamsFromContext pulls the URL parameters from a request context,
// or returns nil if none are present.
func ParamsFromContext(ctx context.Context) Params {
p, _ := ctx.Value(ParamsKey).(Params)
return p
}
// Router is a http.Handler which can be used to dispatch requests to different
// handler functions via configurable routes
type Router struct {
trees map[string]*node
// If enabled, the router checks if another method is allowed for the
// current route, if the current request can not be routed.
// If this is the case, the request is answered with 'Method Not Allowed'
// and HTTP status code 405.
// If no other Method is allowed, the request is delegated to the NotFound
// handler.
HandleMethodNotAllowed bool
// If enabled, the router automatically replies to OPTIONS requests.
// Custom OPTIONS handlers take priority over automatic replies.
HandleOPTIONS bool
// An optional http.Handler that is called on automatic OPTIONS requests.
// The handler is only called if HandleOPTIONS is true and no OPTIONS
// handler for the specific path was set.
// The "Allowed" header is set before calling the handler.
GlobalOPTIONS http.Handler
// Cached value of global (*) allowed methods
globalAllowed string
// Configurable http.Handler which is called when no matching route is
// found. If it is not set, http.NotFound is used.
NotFound http.Handler
// Configurable http.Handler which is called when a request
// cannot be routed and HandleMethodNotAllowed is true.
// If it is not set, http.Error with http.StatusMethodNotAllowed is used.
// The "Allow" header with allowed request methods is set before the handler
// is called.
MethodNotAllowed http.Handler
// Function to handle panics recovered from http handlers.
// It should be used to generate a error page and return the http error code
// 500 (Internal Server Error).
// The handler can be used to keep your server from crashing because of
// unrecovered panics.
PanicHandler func(http.ResponseWriter, *http.Request, interface{})
// If enabled, the router prefers URL.RawPath for route matching instead of the unescaped URL.Path.
UseRawPath bool
// If enabled, the router tries to fix the current request path, if no
// handle is registered for it.
// First superfluous path elements like ../ or // are removed.
// Afterwards the router does a case-insensitive lookup of the cleaned path.
// If a handle can be found for this route, the router makes a redirection
// to the corrected path with status code 301 for GET requests and 308 for
// all other request methods.
// For example /FOO and /..//Foo could be redirected to /foo.
// RedirectTrailingSlash is independent of this option.
RedirectFixedPath bool
// Enables automatic redirection if the current route can't be matched but a
// handler for the path with (without) the trailing slash exists.
// For example if /foo/ is requested but a route only exists for /foo, the
// client is redirected to /foo with http status code 301 for GET requests
// and 308 for all other request methods.
RedirectTrailingSlash bool
// An optional handler that is called if any redirect is made by the router. If not provided,
// a regular http.Redirect call is made.
RedirectHandler func(http.ResponseWriter, *http.Request, int)
}
// Make sure the Router conforms with the http.Handler interface
var _ http.Handler = New()
// New returns a new initialized Router.
func New() *Router {
return &Router{
HandleMethodNotAllowed: true,
HandleOPTIONS: true,
RedirectTrailingSlash: true,
UseRawPath: false,
RedirectFixedPath: false,
}
}
// GET is a shortcut for router.HandlerFunc(http.MethodGet, path, handle)
func (r *Router) GET(path string, handle func(http.ResponseWriter, *http.Request)) {
r.HandlerFunc(http.MethodGet, path, handle)
}
// HEAD is a shortcut for router.HandlerFunc(http.MethodHead, path, handle)
func (r *Router) HEAD(path string, handle func(http.ResponseWriter, *http.Request)) {
r.HandlerFunc(http.MethodHead, path, handle)
}
// OPTIONS is a shortcut for router.HandlerFunc(http.MethodOptions, path, handle)
func (r *Router) OPTIONS(path string, handle func(http.ResponseWriter, *http.Request)) {
r.HandlerFunc(http.MethodOptions, path, handle)
}
// POST is a shortcut for router.HandlerFunc(http.MethodPost, path, handle)
func (r *Router) POST(path string, handle func(http.ResponseWriter, *http.Request)) {
r.HandlerFunc(http.MethodPost, path, handle)
}
// PUT is a shortcut for router.HandlerFunc(http.MethodPut, path, handle)
func (r *Router) PUT(path string, handle func(http.ResponseWriter, *http.Request)) {
r.HandlerFunc(http.MethodPut, path, handle)
}
// PATCH is a shortcut for router.HandlerFunc(http.MethodPatch, path, handle)
func (r *Router) PATCH(path string, handle func(http.ResponseWriter, *http.Request)) {
r.HandlerFunc(http.MethodPatch, path, handle)
}
// DELETE is a shortcut for router.HandlerFunc(http.MethodDelete, path, handle)
func (r *Router) DELETE(path string, handle func(http.ResponseWriter, *http.Request)) {
r.HandlerFunc(http.MethodDelete, path, handle)
}
// HandlerFunc is an adapter which allows the usage of an http.HandlerFunc as a
// request handle.
func (r *Router) HandlerFunc(method, path string, handle func(http.ResponseWriter, *http.Request)) {
if handle == nil {
panic("handle must not be nil")
}
r.Handler(method, path, http.HandlerFunc(handle))
}
// Handler registers a new request handle with the given path and method.
//
// For GET, POST, PUT, PATCH and DELETE requests the respective shortcut
// functions can be used.
//
// This function is intended for bulk loading and to allow the usage of less
// frequently used, non-standardized or custom methods (e.g. for internal
// communication with a proxy).
func (r *Router) Handler(method, path string, handle http.Handler) {
if method == "" {
panic("method must not be empty")
}
if len(path) < 1 || path[0] != '/' {
panic("path must begin with '/' in path '" + path + "'")
}
if handle == nil {
panic("handle must not be nil")
}
if r.trees == nil {
r.trees = make(map[string]*node)
}
root := r.trees[method]
if root == nil {
root = new(node)
r.trees[method] = root
r.globalAllowed = r.allowed("*", "")
}
root.addRoute(path, handle)
}
func (r *Router) allowed(path, reqMethod string) (allow string) {
allowed := make([]string, 0, 9)
if path == "*" { // server-wide
// empty method is used for internal calls to refresh the cache
if reqMethod == "" {
for method := range r.trees {
if method == http.MethodOptions {
continue
}
// Add request method to list of allowed methods
allowed = append(allowed, method)
}
} else {
return r.globalAllowed
}
} else { // specific path
for method := range r.trees {
// Skip the requested method - we already tried this one
if method == reqMethod || method == http.MethodOptions {
continue
}
foundNode, _ := r.trees[method].search(path)
if foundNode != nil && foundNode.handle != nil {
// Add request method to list of allowed methods
allowed = append(allowed, method)
}
}
}
if len(allowed) > 0 {
// Add request method to list of allowed methods
allowed = append(allowed, http.MethodOptions)
// Sort allowed methods.
// sort.Strings(allowed) unfortunately causes unnecessary allocations
// due to allowed being moved to the heap and interface conversion
for i, l := 1, len(allowed); i < l; i++ {
for j := i; j > 0 && allowed[j] < allowed[j-1]; j-- {
allowed[j], allowed[j-1] = allowed[j-1], allowed[j]
}
}
// return as comma separated list
return strings.Join(allowed, ", ")
}
return
}
func (r *Router) recv(w http.ResponseWriter, req *http.Request) {
if rcv := recover(); rcv != nil {
r.PanicHandler(w, req, rcv)
}
}
func (r *Router) lookup(method, path string) (http.Handler, Params) {
if path == "" {
return nil, nil
}
if root := r.trees[method]; root != nil {
nodeFound, paramValues := root.search(path)
if nodeFound == nil || nodeFound.handle == nil {
return nil, nil
}
if len(paramValues) > 0 {
params := make(Params, len(paramValues))
for i, name := range nodeFound.wildcardNames {
if name == "*" {
params[i] = Param{Key: catchAllParam, Value: paramValues[i]}
} else {
params[i] = Param{Key: name, Value: paramValues[i]}
}
}
return nodeFound.handle, params
}
return nodeFound.handle, nil
}
return nil, nil
}
func (r *Router) redirect(w http.ResponseWriter, req *http.Request, code int) {
if r.RedirectHandler != nil {
r.RedirectHandler(w, req, code)
} else {
http.Redirect(w, req, req.URL.String(), code)
}
}
// ServeHTTP makes the router implement the http.Handler interface.
func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
if r.PanicHandler != nil {
defer r.recv(w, req)
}
path := req.URL.Path
if r.UseRawPath && len(req.URL.RawPath) > 0 {
path = req.URL.RawPath
}
if handle, params := r.lookup(req.Method, path); handle != nil {
if len(params) > 0 {
req = req.WithContext(
context.WithValue(req.Context(), ParamsKey, params),
)
}
handle.ServeHTTP(w, req)
return
}
// No route matched the incoming request. Try any automatic fallbacks that are enabled.
if path != "/" && req.Method != http.MethodConnect {
// Moved Permanently, request with GET method
code := http.StatusMovedPermanently
if req.Method != http.MethodGet {
// Permanent Redirect, request with same method
code = http.StatusPermanentRedirect
}
// Redirect from (e.g.) `/foo/` to `/foo` (or vice-versa):
if r.RedirectTrailingSlash {
// using a separate variable here in case we're using RawPath
fixedPath := fixSlash(path)
if handle, _ := r.lookup(req.Method, fixedPath); handle != nil {
req.URL.Path = fixSlash(req.URL.Path)
r.redirect(w, req, code)
return
}
}
// Redirect from (e.g.) `/../foo/` to `/foo`:
if r.RedirectFixedPath && req.URL.Path != "*" {
fixedPath := CleanPath(path)
if handle, _ := r.lookup(req.Method, fixedPath); handle != nil {
req.URL.Path = fixedPath
r.redirect(w, req, code)
return
}
if r.RedirectTrailingSlash {
fixedPath = fixSlash(fixedPath)
if handle, _ := r.lookup(req.Method, fixedPath); handle != nil {
req.URL.Path = fixedPath
r.redirect(w, req, code)
return
}
}
}
}
if req.Method == http.MethodOptions && r.HandleOPTIONS {
// Handle OPTIONS requests
if allow := r.allowed(path, http.MethodOptions); allow != "" {
w.Header().Set("Allow", allow)
if r.GlobalOPTIONS != nil {
r.GlobalOPTIONS.ServeHTTP(w, req)
}
return
}
} else if r.HandleMethodNotAllowed { // Handle 405
if allow := r.allowed(path, req.Method); allow != "" {
w.Header().Set("Allow", allow)
if r.MethodNotAllowed != nil {
r.MethodNotAllowed.ServeHTTP(w, req)
} else {
http.Error(w,
http.StatusText(http.StatusMethodNotAllowed),
http.StatusMethodNotAllowed,
)
}
return
}
}
// Handle 404
if r.NotFound != nil {
r.NotFound.ServeHTTP(w, req)
} else {
http.NotFound(w, req)
}
}
// Adds or a remove a trailing slash from s
func fixSlash(s string) string {
if len(s) > 1 && s[len(s)-1] == '/' {
return s[:len(s)-1]
}
return s + "/"
}