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// Copyright 2012 The Gorilla Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package mux
import (
"errors"
"fmt"
"net/http"
"path"
"regexp"
)
var (
// ErrMethodMismatch is returned when the method in the request does not match
// the method defined against the route.
ErrMethodMismatch = errors.New("method is not allowed")
// ErrNotFound is returned when no route match is found.
ErrNotFound = errors.New("no matching route was found")
)
// NewRouter returns a new router instance.
func NewRouter() *Router {
return &Router{namedRoutes: make(map[string]*Route), KeepContext: false}
}
// Router registers routes to be matched and dispatches a handler.
//
// It implements the http.Handler interface, so it can be registered to serve
// requests:
//
// var router = mux.NewRouter()
//
// func main() {
// http.Handle("/", router)
// }
//
// Or, for Google App Engine, register it in a init() function:
//
// func init() {
// http.Handle("/", router)
// }
//
// This will send all incoming requests to the router.
type Router struct {
// Configurable Handler to be used when no route matches.
NotFoundHandler http.Handler
// Configurable Handler to be used when the request method does not match the route.
MethodNotAllowedHandler http.Handler
// Parent route, if this is a subrouter.
parent parentRoute
// Routes to be matched, in order.
routes []*Route
// Routes by name for URL building.
namedRoutes map[string]*Route
// See Router.StrictSlash(). This defines the flag for new routes.
strictSlash bool
// See Router.SkipClean(). This defines the flag for new routes.
skipClean bool
// If true, do not clear the request context after handling the request.
// This has no effect when go1.7+ is used, since the context is stored
// on the request itself.
KeepContext bool
// see Router.UseEncodedPath(). This defines a flag for all routes.
useEncodedPath bool
// Slice of middlewares to be called after a match is found
middlewares []middleware
}
// Match attempts to match the given request against the router's registered routes.
//
// If the request matches a route of this router or one of its subrouters the Route,
// Handler, and Vars fields of the the match argument are filled and this function
// returns true.
//
// If the request does not match any of this router's or its subrouters' routes
// then this function returns false. If available, a reason for the match failure
// will be filled in the match argument's MatchErr field. If the match failure type
// (eg: not found) has a registered handler, the handler is assigned to the Handler
// field of the match argument.
func (r *Router) Match(req *http.Request, match *RouteMatch) bool {
for _, route := range r.routes {
if route.Match(req, match) {
// Build middleware chain if no error was found
if match.MatchErr == nil {
for i := len(r.middlewares) - 1; i >= 0; i-- {
match.Handler = r.middlewares[i].Middleware(match.Handler)
}
}
return true
}
}
if match.MatchErr == ErrMethodMismatch {
if r.MethodNotAllowedHandler != nil {
match.Handler = r.MethodNotAllowedHandler
return true
}
return false
}
// Closest match for a router (includes sub-routers)
if r.NotFoundHandler != nil {
match.Handler = r.NotFoundHandler
match.MatchErr = ErrNotFound
return true
}
match.MatchErr = ErrNotFound
return false
}
// ServeHTTP dispatches the handler registered in the matched route.
//
// When there is a match, the route variables can be retrieved calling
// mux.Vars(request).
func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
if !r.skipClean {
path := req.URL.Path
if r.useEncodedPath {
path = req.URL.EscapedPath()
}
// Clean path to canonical form and redirect.
if p := cleanPath(path); p != path {
// Added 3 lines (Philip Schlump) - It was dropping the query string and #whatever from query.
// This matches with fix in go 1.2 r.c. 4 for same problem. Go Issue:
// http://code.google.com/p/go/issues/detail?id=5252
url := *req.URL
url.Path = p
p = url.String()
w.Header().Set("Location", p)
w.WriteHeader(http.StatusMovedPermanently)
return
}
}
var match RouteMatch
var handler http.Handler
if r.Match(req, &match) {
handler = match.Handler
req = setVars(req, match.Vars)
req = setCurrentRoute(req, match.Route)
}
if handler == nil && match.MatchErr == ErrMethodMismatch {
handler = methodNotAllowedHandler()
}
if handler == nil {
handler = http.NotFoundHandler()
}
if !r.KeepContext {
defer contextClear(req)
}
handler.ServeHTTP(w, req)
}
// Get returns a route registered with the given name.
func (r *Router) Get(name string) *Route {
return r.getNamedRoutes()[name]
}
// GetRoute returns a route registered with the given name. This method
// was renamed to Get() and remains here for backwards compatibility.
func (r *Router) GetRoute(name string) *Route {
return r.getNamedRoutes()[name]
}
// StrictSlash defines the trailing slash behavior for new routes. The initial
// value is false.
//
// When true, if the route path is "/path/", accessing "/path" will perform a redirect
// to the former and vice versa. In other words, your application will always
// see the path as specified in the route.
//
// When false, if the route path is "/path", accessing "/path/" will not match
// this route and vice versa.
//
// The re-direct is a HTTP 301 (Moved Permanently). Note that when this is set for
// routes with a non-idempotent method (e.g. POST, PUT), the subsequent re-directed
// request will be made as a GET by most clients. Use middleware or client settings
// to modify this behaviour as needed.
//
// Special case: when a route sets a path prefix using the PathPrefix() method,
// strict slash is ignored for that route because the redirect behavior can't
// be determined from a prefix alone. However, any subrouters created from that
// route inherit the original StrictSlash setting.
func (r *Router) StrictSlash(value bool) *Router {
r.strictSlash = value
return r
}
// SkipClean defines the path cleaning behaviour for new routes. The initial
// value is false. Users should be careful about which routes are not cleaned
//
// When true, if the route path is "/path//to", it will remain with the double
// slash. This is helpful if you have a route like: /fetch/http://xkcd.com/534/
//
// When false, the path will be cleaned, so /fetch/http://xkcd.com/534/ will
// become /fetch/http/xkcd.com/534
func (r *Router) SkipClean(value bool) *Router {
r.skipClean = value
return r
}
// UseEncodedPath tells the router to match the encoded original path
// to the routes.
// For eg. "/path/foo%2Fbar/to" will match the path "/path/{var}/to".
//
// If not called, the router will match the unencoded path to the routes.
// For eg. "/path/foo%2Fbar/to" will match the path "/path/foo/bar/to"
func (r *Router) UseEncodedPath() *Router {
r.useEncodedPath = true
return r
}
// ----------------------------------------------------------------------------
// parentRoute
// ----------------------------------------------------------------------------
func (r *Router) getBuildScheme() string {
if r.parent != nil {
return r.parent.getBuildScheme()
}
return ""
}
// getNamedRoutes returns the map where named routes are registered.
func (r *Router) getNamedRoutes() map[string]*Route {
if r.namedRoutes == nil {
if r.parent != nil {
r.namedRoutes = r.parent.getNamedRoutes()
} else {
r.namedRoutes = make(map[string]*Route)
}
}
return r.namedRoutes
}
// getRegexpGroup returns regexp definitions from the parent route, if any.
func (r *Router) getRegexpGroup() *routeRegexpGroup {
if r.parent != nil {
return r.parent.getRegexpGroup()
}
return nil
}
func (r *Router) buildVars(m map[string]string) map[string]string {
if r.parent != nil {
m = r.parent.buildVars(m)
}
return m
}
// ----------------------------------------------------------------------------
// Route factories
// ----------------------------------------------------------------------------
// NewRoute registers an empty route.
func (r *Router) NewRoute() *Route {
route := &Route{parent: r, strictSlash: r.strictSlash, skipClean: r.skipClean, useEncodedPath: r.useEncodedPath}
r.routes = append(r.routes, route)
return route
}
// Handle registers a new route with a matcher for the URL path.
// See Route.Path() and Route.Handler().
func (r *Router) Handle(path string, handler http.Handler) *Route {
return r.NewRoute().Path(path).Handler(handler)
}
// HandleFunc registers a new route with a matcher for the URL path.
// See Route.Path() and Route.HandlerFunc().
func (r *Router) HandleFunc(path string, f func(http.ResponseWriter,
*http.Request)) *Route {
return r.NewRoute().Path(path).HandlerFunc(f)
}
// Headers registers a new route with a matcher for request header values.
// See Route.Headers().
func (r *Router) Headers(pairs ...string) *Route {
return r.NewRoute().Headers(pairs...)
}
// Host registers a new route with a matcher for the URL host.
// See Route.Host().
func (r *Router) Host(tpl string) *Route {
return r.NewRoute().Host(tpl)
}
// MatcherFunc registers a new route with a custom matcher function.
// See Route.MatcherFunc().
func (r *Router) MatcherFunc(f MatcherFunc) *Route {
return r.NewRoute().MatcherFunc(f)
}
// Methods registers a new route with a matcher for HTTP methods.
// See Route.Methods().
func (r *Router) Methods(methods ...string) *Route {
return r.NewRoute().Methods(methods...)
}
// Path registers a new route with a matcher for the URL path.
// See Route.Path().
func (r *Router) Path(tpl string) *Route {
return r.NewRoute().Path(tpl)
}
// PathPrefix registers a new route with a matcher for the URL path prefix.
// See Route.PathPrefix().
func (r *Router) PathPrefix(tpl string) *Route {
return r.NewRoute().PathPrefix(tpl)
}
// Queries registers a new route with a matcher for URL query values.
// See Route.Queries().
func (r *Router) Queries(pairs ...string) *Route {
return r.NewRoute().Queries(pairs...)
}
// Schemes registers a new route with a matcher for URL schemes.
// See Route.Schemes().
func (r *Router) Schemes(schemes ...string) *Route {
return r.NewRoute().Schemes(schemes...)
}
// BuildVarsFunc registers a new route with a custom function for modifying
// route variables before building a URL.
func (r *Router) BuildVarsFunc(f BuildVarsFunc) *Route {
return r.NewRoute().BuildVarsFunc(f)
}
// Walk walks the router and all its sub-routers, calling walkFn for each route
// in the tree. The routes are walked in the order they were added. Sub-routers
// are explored depth-first.
func (r *Router) Walk(walkFn WalkFunc) error {
return r.walk(walkFn, []*Route{})
}
// SkipRouter is used as a return value from WalkFuncs to indicate that the
// router that walk is about to descend down to should be skipped.
var SkipRouter = errors.New("skip this router")
// WalkFunc is the type of the function called for each route visited by Walk.
// At every invocation, it is given the current route, and the current router,
// and a list of ancestor routes that lead to the current route.
type WalkFunc func(route *Route, router *Router, ancestors []*Route) error
func (r *Router) walk(walkFn WalkFunc, ancestors []*Route) error {
for _, t := range r.routes {
err := walkFn(t, r, ancestors)
if err == SkipRouter {
continue
}
if err != nil {
return err
}
for _, sr := range t.matchers {
if h, ok := sr.(*Router); ok {
ancestors = append(ancestors, t)
err := h.walk(walkFn, ancestors)
if err != nil {
return err
}
ancestors = ancestors[:len(ancestors)-1]
}
}
if h, ok := t.handler.(*Router); ok {
ancestors = append(ancestors, t)
err := h.walk(walkFn, ancestors)
if err != nil {
return err
}
ancestors = ancestors[:len(ancestors)-1]
}
}
return nil
}
// ----------------------------------------------------------------------------
// Context
// ----------------------------------------------------------------------------
// RouteMatch stores information about a matched route.
type RouteMatch struct {
Route *Route
Handler http.Handler
Vars map[string]string
// MatchErr is set to appropriate matching error
// It is set to ErrMethodMismatch if there is a mismatch in
// the request method and route method
MatchErr error
}
type contextKey int
const (
varsKey contextKey = iota
routeKey
)
// Vars returns the route variables for the current request, if any.
func Vars(r *http.Request) map[string]string {
if rv := contextGet(r, varsKey); rv != nil {
return rv.(map[string]string)
}
return nil
}
// CurrentRoute returns the matched route for the current request, if any.
// This only works when called inside the handler of the matched route
// because the matched route is stored in the request context which is cleared
// after the handler returns, unless the KeepContext option is set on the
// Router.
func CurrentRoute(r *http.Request) *Route {
if rv := contextGet(r, routeKey); rv != nil {
return rv.(*Route)
}
return nil
}
func setVars(r *http.Request, val interface{}) *http.Request {
return contextSet(r, varsKey, val)
}
func setCurrentRoute(r *http.Request, val interface{}) *http.Request {
return contextSet(r, routeKey, val)
}
// ----------------------------------------------------------------------------
// Helpers
// ----------------------------------------------------------------------------
// cleanPath returns the canonical path for p, eliminating . and .. elements.
// Borrowed from the net/http package.
func cleanPath(p string) string {
if p == "" {
return "/"
}
if p[0] != '/' {
p = "/" + p
}
np := path.Clean(p)
// path.Clean removes trailing slash except for root;
// put the trailing slash back if necessary.
if p[len(p)-1] == '/' && np != "/" {
np += "/"
}
return np
}
// uniqueVars returns an error if two slices contain duplicated strings.
func uniqueVars(s1, s2 []string) error {
for _, v1 := range s1 {
for _, v2 := range s2 {
if v1 == v2 {
return fmt.Errorf("mux: duplicated route variable %q", v2)
}
}
}
return nil
}
// checkPairs returns the count of strings passed in, and an error if
// the count is not an even number.
func checkPairs(pairs ...string) (int, error) {
length := len(pairs)
if length%2 != 0 {
return length, fmt.Errorf(
"mux: number of parameters must be multiple of 2, got %v", pairs)
}
return length, nil
}
// mapFromPairsToString converts variadic string parameters to a
// string to string map.
func mapFromPairsToString(pairs ...string) (map[string]string, error) {
length, err := checkPairs(pairs...)
if err != nil {
return nil, err
}
m := make(map[string]string, length/2)
for i := 0; i < length; i += 2 {
m[pairs[i]] = pairs[i+1]
}
return m, nil
}
// mapFromPairsToRegex converts variadic string parameters to a
// string to regex map.
func mapFromPairsToRegex(pairs ...string) (map[string]*regexp.Regexp, error) {
length, err := checkPairs(pairs...)
if err != nil {
return nil, err
}
m := make(map[string]*regexp.Regexp, length/2)
for i := 0; i < length; i += 2 {
regex, err := regexp.Compile(pairs[i+1])
if err != nil {
return nil, err
}
m[pairs[i]] = regex
}
return m, nil
}
// matchInArray returns true if the given string value is in the array.
func matchInArray(arr []string, value string) bool {
for _, v := range arr {
if v == value {
return true
}
}
return false
}
// matchMapWithString returns true if the given key/value pairs exist in a given map.
func matchMapWithString(toCheck map[string]string, toMatch map[string][]string, canonicalKey bool) bool {
for k, v := range toCheck {
// Check if key exists.
if canonicalKey {
k = http.CanonicalHeaderKey(k)
}
if values := toMatch[k]; values == nil {
return false
} else if v != "" {
// If value was defined as an empty string we only check that the
// key exists. Otherwise we also check for equality.
valueExists := false
for _, value := range values {
if v == value {
valueExists = true
break
}
}
if !valueExists {
return false
}
}
}
return true
}
// matchMapWithRegex returns true if the given key/value pairs exist in a given map compiled against
// the given regex
func matchMapWithRegex(toCheck map[string]*regexp.Regexp, toMatch map[string][]string, canonicalKey bool) bool {
for k, v := range toCheck {
// Check if key exists.
if canonicalKey {
k = http.CanonicalHeaderKey(k)
}
if values := toMatch[k]; values == nil {
return false
} else if v != nil {
// If value was defined as an empty string we only check that the
// key exists. Otherwise we also check for equality.
valueExists := false
for _, value := range values {
if v.MatchString(value) {
valueExists = true
break
}
}
if !valueExists {
return false
}
}
}
return true
}
// methodNotAllowed replies to the request with an HTTP status code 405.
func methodNotAllowed(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusMethodNotAllowed)
}
// methodNotAllowedHandler returns a simple request handler
// that replies to each request with a status code 405.
func methodNotAllowedHandler() http.Handler { return http.HandlerFunc(methodNotAllowed) }