400 lines
13 KiB
Go
400 lines
13 KiB
Go
// Copyright 2013 Julien Schmidt. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be found
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// in the LICENSE file.
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// Package httprouter is a trie based high performance HTTP request router.
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//
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// A trivial example is:
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//
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// package main
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//
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// import (
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// "fmt"
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// "github.com/julienschmidt/httprouter"
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// "net/http"
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// "log"
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// )
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//
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// func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
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// fmt.Fprint(w, "Welcome!\n")
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// }
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//
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// func Hello(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
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// fmt.Fprintf(w, "hello, %s!\n", ps.ByName("name"))
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// }
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//
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// func main() {
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// router := httprouter.New()
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// router.GET("/", Index)
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// router.GET("/hello/:name", Hello)
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//
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// log.Fatal(http.ListenAndServe(":8080", router))
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// }
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//
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// The router matches incoming requests by the request method and the path.
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// If a handle is registered for this path and method, the router delegates the
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// request to that function.
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// For the methods GET, POST, PUT, PATCH and DELETE shortcut functions exist to
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// register handles, for all other methods router.Handle can be used.
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//
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// The registered path, against which the router matches incoming requests, can
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// contain two types of parameters:
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// Syntax Type
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// :name named parameter
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// *name catch-all parameter
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//
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// Named parameters are dynamic path segments. They match anything until the
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// next '/' or the path end:
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// Path: /blog/:category/:post
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//
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// Requests:
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// /blog/go/request-routers match: category="go", post="request-routers"
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// /blog/go/request-routers/ no match, but the router would redirect
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// /blog/go/ no match
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// /blog/go/request-routers/comments no match
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//
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// Catch-all parameters match anything until the path end, including the
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// directory index (the '/' before the catch-all). Since they match anything
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// until the end, catch-all parameters must always be the final path element.
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// Path: /files/*filepath
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//
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// Requests:
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// /files/ match: filepath="/"
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// /files/LICENSE match: filepath="/LICENSE"
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// /files/templates/article.html match: filepath="/templates/article.html"
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// /files no match, but the router would redirect
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//
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// The value of parameters is saved as a slice of the Param struct, consisting
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// each of a key and a value. The slice is passed to the Handle func as a third
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// parameter.
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// There are two ways to retrieve the value of a parameter:
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// // by the name of the parameter
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// user := ps.ByName("user") // defined by :user or *user
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//
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// // by the index of the parameter. This way you can also get the name (key)
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// thirdKey := ps[2].Key // the name of the 3rd parameter
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// thirdValue := ps[2].Value // the value of the 3rd parameter
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package httprouter
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import (
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"net/http"
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)
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// Handle is a function that can be registered to a route to handle HTTP
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// requests. Like http.HandlerFunc, but has a third parameter for the values of
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// wildcards (variables).
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type Handle func(http.ResponseWriter, *http.Request, Params)
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// Param is a single URL parameter, consisting of a key and a value.
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type Param struct {
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Key string
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Value string
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}
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// Params is a Param-slice, as returned by the router.
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// The slice is ordered, the first URL parameter is also the first slice value.
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// It is therefore safe to read values by the index.
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type Params []Param
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// ByName returns the value of the first Param which key matches the given name.
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// If no matching Param is found, an empty string is returned.
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func (ps Params) ByName(name string) string {
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for i := range ps {
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if ps[i].Key == name {
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return ps[i].Value
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}
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}
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return ""
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}
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// Router is a http.Handler which can be used to dispatch requests to different
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// handler functions via configurable routes
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type Router struct {
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trees map[string]*node
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// Enables automatic redirection if the current route can't be matched but a
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// handler for the path with (without) the trailing slash exists.
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// For example if /foo/ is requested but a route only exists for /foo, the
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// client is redirected to /foo with http status code 301 for GET requests
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// and 307 for all other request methods.
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RedirectTrailingSlash bool
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// If enabled, the router tries to fix the current request path, if no
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// handle is registered for it.
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// First superfluous path elements like ../ or // are removed.
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// Afterwards the router does a case-insensitive lookup of the cleaned path.
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// If a handle can be found for this route, the router makes a redirection
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// to the corrected path with status code 301 for GET requests and 307 for
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// all other request methods.
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// For example /FOO and /..//Foo could be redirected to /foo.
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// RedirectTrailingSlash is independent of this option.
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RedirectFixedPath bool
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// If enabled, the router checks if another method is allowed for the
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// current route, if the current request can not be routed.
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// If this is the case, the request is answered with 'Method Not Allowed'
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// and HTTP status code 405.
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// If no other Method is allowed, the request is delegated to the NotFound
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// handler.
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HandleMethodNotAllowed bool
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// If enabled, the router automatically replies to OPTIONS requests.
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// Custom OPTIONS handlers take priority over automatic replies.
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HandleOPTIONS bool
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// Configurable http.Handler which is called when no matching route is
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// found. If it is not set, http.NotFound is used.
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NotFound http.Handler
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// Configurable http.Handler which is called when a request
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// cannot be routed and HandleMethodNotAllowed is true.
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// If it is not set, http.Error with http.StatusMethodNotAllowed is used.
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// The "Allow" header with allowed request methods is set before the handler
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// is called.
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MethodNotAllowed http.Handler
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// Function to handle panics recovered from http handlers.
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// It should be used to generate a error page and return the http error code
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// 500 (Internal Server Error).
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// The handler can be used to keep your server from crashing because of
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// unrecovered panics.
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PanicHandler func(http.ResponseWriter, *http.Request, interface{})
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}
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// Make sure the Router conforms with the http.Handler interface
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var _ http.Handler = New()
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// New returns a new initialized Router.
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// Path auto-correction, including trailing slashes, is enabled by default.
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func New() *Router {
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return &Router{
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RedirectTrailingSlash: true,
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RedirectFixedPath: true,
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HandleMethodNotAllowed: true,
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HandleOPTIONS: true,
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}
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}
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// GET is a shortcut for router.Handle("GET", path, handle)
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func (r *Router) GET(path string, handle Handle) {
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r.Handle("GET", path, handle)
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}
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// HEAD is a shortcut for router.Handle("HEAD", path, handle)
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func (r *Router) HEAD(path string, handle Handle) {
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r.Handle("HEAD", path, handle)
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}
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// OPTIONS is a shortcut for router.Handle("OPTIONS", path, handle)
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func (r *Router) OPTIONS(path string, handle Handle) {
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r.Handle("OPTIONS", path, handle)
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}
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// POST is a shortcut for router.Handle("POST", path, handle)
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func (r *Router) POST(path string, handle Handle) {
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r.Handle("POST", path, handle)
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}
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// PUT is a shortcut for router.Handle("PUT", path, handle)
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func (r *Router) PUT(path string, handle Handle) {
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r.Handle("PUT", path, handle)
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}
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// PATCH is a shortcut for router.Handle("PATCH", path, handle)
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func (r *Router) PATCH(path string, handle Handle) {
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r.Handle("PATCH", path, handle)
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}
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// DELETE is a shortcut for router.Handle("DELETE", path, handle)
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func (r *Router) DELETE(path string, handle Handle) {
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r.Handle("DELETE", path, handle)
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}
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// Handle registers a new request handle with the given path and method.
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//
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// For GET, POST, PUT, PATCH and DELETE requests the respective shortcut
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// functions can be used.
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//
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// This function is intended for bulk loading and to allow the usage of less
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// frequently used, non-standardized or custom methods (e.g. for internal
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// communication with a proxy).
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func (r *Router) Handle(method, path string, handle Handle) {
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if path[0] != '/' {
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panic("path must begin with '/' in path '" + path + "'")
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}
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if r.trees == nil {
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r.trees = make(map[string]*node)
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}
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root := r.trees[method]
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if root == nil {
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root = new(node)
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r.trees[method] = root
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}
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root.addRoute(path, handle)
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}
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// HandlerFunc is an adapter which allows the usage of an http.HandlerFunc as a
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// request handle.
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func (r *Router) HandlerFunc(method, path string, handler http.HandlerFunc) {
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r.Handler(method, path, handler)
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}
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// ServeFiles serves files from the given file system root.
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// The path must end with "/*filepath", files are then served from the local
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// path /defined/root/dir/*filepath.
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// For example if root is "/etc" and *filepath is "passwd", the local file
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// "/etc/passwd" would be served.
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// Internally a http.FileServer is used, therefore http.NotFound is used instead
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// of the Router's NotFound handler.
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// To use the operating system's file system implementation,
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// use http.Dir:
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// router.ServeFiles("/src/*filepath", http.Dir("/var/www"))
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func (r *Router) ServeFiles(path string, root http.FileSystem) {
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if len(path) < 10 || path[len(path)-10:] != "/*filepath" {
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panic("path must end with /*filepath in path '" + path + "'")
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}
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fileServer := http.FileServer(root)
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r.GET(path, func(w http.ResponseWriter, req *http.Request, ps Params) {
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req.URL.Path = ps.ByName("filepath")
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fileServer.ServeHTTP(w, req)
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})
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}
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func (r *Router) recv(w http.ResponseWriter, req *http.Request) {
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if rcv := recover(); rcv != nil {
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r.PanicHandler(w, req, rcv)
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}
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}
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// Lookup allows the manual lookup of a method + path combo.
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// This is e.g. useful to build a framework around this router.
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// If the path was found, it returns the handle function and the path parameter
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// values. Otherwise the third return value indicates whether a redirection to
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// the same path with an extra / without the trailing slash should be performed.
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func (r *Router) Lookup(method, path string) (Handle, Params, bool) {
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if root := r.trees[method]; root != nil {
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return root.getValue(path)
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}
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return nil, nil, false
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}
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func (r *Router) allowed(path, reqMethod string) (allow string) {
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if path == "*" { // server-wide
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for method := range r.trees {
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if method == "OPTIONS" {
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continue
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}
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// add request method to list of allowed methods
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if len(allow) == 0 {
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allow = method
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} else {
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allow += ", " + method
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}
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}
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} else { // specific path
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for method := range r.trees {
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// Skip the requested method - we already tried this one
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if method == reqMethod || method == "OPTIONS" {
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continue
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}
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handle, _, _ := r.trees[method].getValue(path)
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if handle != nil {
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// add request method to list of allowed methods
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if len(allow) == 0 {
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allow = method
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} else {
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allow += ", " + method
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}
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}
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}
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}
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if len(allow) > 0 {
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allow += ", OPTIONS"
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}
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return
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}
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// ServeHTTP makes the router implement the http.Handler interface.
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func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
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if r.PanicHandler != nil {
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defer r.recv(w, req)
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}
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path := req.URL.Path
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if root := r.trees[req.Method]; root != nil {
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if handle, ps, tsr := root.getValue(path); handle != nil {
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handle(w, req, ps)
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return
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} else if req.Method != "CONNECT" && path != "/" {
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code := 301 // Permanent redirect, request with GET method
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if req.Method != "GET" {
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// Temporary redirect, request with same method
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// As of Go 1.3, Go does not support status code 308.
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code = 307
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}
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if tsr && r.RedirectTrailingSlash {
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if len(path) > 1 && path[len(path)-1] == '/' {
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req.URL.Path = path[:len(path)-1]
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} else {
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req.URL.Path = path + "/"
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}
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http.Redirect(w, req, req.URL.String(), code)
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return
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}
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// Try to fix the request path
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if r.RedirectFixedPath {
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fixedPath, found := root.findCaseInsensitivePath(
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CleanPath(path),
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r.RedirectTrailingSlash,
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)
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if found {
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req.URL.Path = string(fixedPath)
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http.Redirect(w, req, req.URL.String(), code)
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return
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}
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}
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}
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}
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if req.Method == "OPTIONS" && r.HandleOPTIONS {
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// Handle OPTIONS requests
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if allow := r.allowed(path, req.Method); len(allow) > 0 {
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w.Header().Set("Allow", allow)
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return
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}
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} else {
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// Handle 405
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if r.HandleMethodNotAllowed {
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if allow := r.allowed(path, req.Method); len(allow) > 0 {
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w.Header().Set("Allow", allow)
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if r.MethodNotAllowed != nil {
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r.MethodNotAllowed.ServeHTTP(w, req)
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} else {
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http.Error(w,
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http.StatusText(http.StatusMethodNotAllowed),
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http.StatusMethodNotAllowed,
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)
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}
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return
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}
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}
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}
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// Handle 404
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if r.NotFound != nil {
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r.NotFound.ServeHTTP(w, req)
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} else {
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http.NotFound(w, req)
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}
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}
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