[docs] Improve docstrings for middleware, skipclean (#375)

The example in the README does not pass the request through a mux therefore the request variables from the path are never populated. Update the sample to create a minimum viable router to use.

Fixes #373

.travis.yml

@@ -3,13 +3,14 @@ sudo: false
 
 matrix:
   include:
-    - go: 1.2
-    - go: 1.3
-    - go: 1.4
-    - go: 1.5
-    - go: 1.6
-    - go: 1.7
-    - go: 1.8
+    - go: 1.5.x
+    - go: 1.6.x
+    - go: 1.7.x
+    - go: 1.8.x
+    - go: 1.9.x
+    - go: 1.10.x
+    - go: tip
+  allow_failures:
     - go: tip
 
 install:

ISSUE_TEMPLATE.md

@@ -0,0 +1,11 @@
+**What version of Go are you running?** (Paste the output of `go version`)
+
+
+**What version of gorilla/mux are you at?** (Paste the output of `git rev-parse HEAD` inside `$GOPATH/src/github.com/gorilla/mux`)
+
+
+**Describe your problem** (and what you have tried so far)
+
+
+**Paste a minimal, runnable, reproduction of your issue below** (use backticks to format it)
+

README.md

@@ -1,5 +1,5 @@
-gorilla/mux
-===
+# gorilla/mux
+
 [![GoDoc](https://godoc.org/github.com/gorilla/mux?status.svg)](https://godoc.org/github.com/gorilla/mux)
 [![Build Status](https://travis-ci.org/gorilla/mux.svg?branch=master)](https://travis-ci.org/gorilla/mux)
 [![Sourcegraph](https://sourcegraph.com/github.com/gorilla/mux/-/badge.svg)](https://sourcegraph.com/github.com/gorilla/mux?badge)
@@ -15,7 +15,7 @@ The name mux stands for "HTTP request multiplexer". Like the standard `http.Serv
 
 * It implements the `http.Handler` interface so it is compatible with the standard `http.ServeMux`.
 * Requests can be matched based on URL host, path, path prefix, schemes, header and query values, HTTP methods or using custom matchers.
-* URL hosts and paths can have variables with an optional regular expression.
+* URL hosts, paths and query values can have variables with an optional regular expression.
 * Registered URLs can be built, or "reversed", which helps maintaining references to resources.
 * Routes can be used as subrouters: nested routes are only tested if the parent route matches. This is useful to define groups of routes that share common conditions like a host, a path prefix or other repeated attributes. As a bonus, this optimizes request matching.
 
@@ -24,9 +24,12 @@ The name mux stands for "HTTP request multiplexer". Like the standard `http.Serv
 * [Install](#install)
 * [Examples](#examples)
 * [Matching Routes](#matching-routes)
-* [Listing Routes](#listing-routes)
 * [Static Files](#static-files)
 * [Registered URLs](#registered-urls)
+* [Walking Routes](#walking-routes)
+* [Graceful Shutdown](#graceful-shutdown)
+* [Middleware](#middleware)
+* [Testing Handlers](#testing-handlers)
 * [Full Example](#full-example)
 
 ---
@@ -45,11 +48,11 @@ Let's start registering a couple of URL paths and handlers:
 
 ```go
 func main() {
-	r := mux.NewRouter()
-	r.HandleFunc("/", HomeHandler)
-	r.HandleFunc("/products", ProductsHandler)
-	r.HandleFunc("/articles", ArticlesHandler)
-	http.Handle("/", r)
+    r := mux.NewRouter()
+    r.HandleFunc("/", HomeHandler)
+    r.HandleFunc("/products", ProductsHandler)
+    r.HandleFunc("/articles", ArticlesHandler)
+    http.Handle("/", r)
 }
 ```
 
@@ -68,9 +71,9 @@ The names are used to create a map of route variables which can be retrieved cal
 
 ```go
 func ArticlesCategoryHandler(w http.ResponseWriter, r *http.Request) {
-	vars := mux.Vars(r)
-	w.WriteHeader(http.StatusOK)
-	fmt.Fprintf(w, "Category: %v\n", vars["category"])
+    vars := mux.Vars(r)
+    w.WriteHeader(http.StatusOK)
+    fmt.Fprintf(w, "Category: %v\n", vars["category"])
 }
 ```
 
@@ -122,7 +125,7 @@ r.Queries("key", "value")
 
 ```go
 r.MatcherFunc(func(r *http.Request, rm *RouteMatch) bool {
-	return r.ProtoMajor == 0
+    return r.ProtoMajor == 0
 })
 ```
 
@@ -135,6 +138,14 @@ r.HandleFunc("/products", ProductsHandler).
   Schemes("http")
 ```
 
+Routes are tested in the order they were added to the router. If two routes match, the first one wins:
+
+```go
+r := mux.NewRouter()
+r.HandleFunc("/specific", specificHandler)
+r.PathPrefix("/").Handler(catchAllHandler)
+```
+
 Setting the same matching conditions again and again can be boring, so we have a way to group several routes that share the same requirements. We call it "subrouting".
 
 For example, let's say we have several URLs that should only match when the host is `www.example.com`. Create a route for that host and get a "subrouter" from it:
@@ -169,79 +180,33 @@ s.HandleFunc("/{key}/", ProductHandler)
 s.HandleFunc("/{key}/details", ProductDetailsHandler)
 ```
 
-### Listing Routes
-
-Routes on a mux can be listed using the Router.Walk method—useful for generating documentation:
-
-```go
-package main
-
-import (
-    "fmt"
-    "net/http"
-    "strings"
-
-    "github.com/gorilla/mux"
-)
-
-func handler(w http.ResponseWriter, r *http.Request) {
-    return
-}
-
-func main() {
-    r := mux.NewRouter()
-    r.HandleFunc("/", handler)
-    r.Methods("POST").HandleFunc("/products", handler)
-    r.Methods("GET").HandleFunc("/articles", handler)
-    r.Methods("GET", "PUT").HandleFunc("/articles/{id}", handler)
-    r.Walk(func(route *mux.Route, router *mux.Router, ancestors []*mux.Route) error {
-        t, err := route.GetPathTemplate()
-        if err != nil {
-            return err
-        }
-        // p will contain regular expression is compatible with regular expression in Perl, Python, and other languages.
-        // for instance the regular expression for path '/articles/{id}' will be '^/articles/(?P<v0>[^/]+)$'
-        p, err := route.GetPathRegexp()
-        if err != nil {
-            return err
-        }
-        m, err := route.GetMethods()
-        if err != nil {
-            return err
-        }
-        fmt.Println(strings.Join(m, ","), t, p)
-        return nil
-    })
-    http.Handle("/", r)
-}
-```
 
 ### Static Files
 
 Note that the path provided to `PathPrefix()` represents a "wildcard": calling
 `PathPrefix("/static/").Handler(...)` means that the handler will be passed any
-request that matches "/static/*". This makes it easy to serve static files with mux:
+request that matches "/static/\*". This makes it easy to serve static files with mux:
 
 ```go
 func main() {
-	var dir string
+    var dir string
 
-	flag.StringVar(&dir, "dir", ".", "the directory to serve files from. Defaults to the current dir")
-	flag.Parse()
-	r := mux.NewRouter()
+    flag.StringVar(&dir, "dir", ".", "the directory to serve files from. Defaults to the current dir")
+    flag.Parse()
+    r := mux.NewRouter()
 
-	// This will serve files under http://localhost:8000/static/<filename>
-	r.PathPrefix("/static/").Handler(http.StripPrefix("/static/", http.FileServer(http.Dir(dir))))
+    // This will serve files under http://localhost:8000/static/<filename>
+    r.PathPrefix("/static/").Handler(http.StripPrefix("/static/", http.FileServer(http.Dir(dir))))
 
-	srv := &http.Server{
-		Handler:      r,
-		Addr:         "127.0.0.1:8000",
-		// Good practice: enforce timeouts for servers you create!
-		WriteTimeout: 15 * time.Second,
-		ReadTimeout:  15 * time.Second,
-	}
+    srv := &http.Server{
+        Handler:      r,
+        Addr:         "127.0.0.1:8000",
+        // Good practice: enforce timeouts for servers you create!
+        WriteTimeout: 15 * time.Second,
+        ReadTimeout:  15 * time.Second,
+    }
 
-	log.Fatal(srv.ListenAndServe())
+    log.Fatal(srv.ListenAndServe())
 }
 ```
 
@@ -269,19 +234,21 @@ url, err := r.Get("article").URL("category", "technology", "id", "42")
 "/articles/technology/42"
 ```
 
-This also works for host variables:
+This also works for host and query value variables:
 
 ```go
 r := mux.NewRouter()
 r.Host("{subdomain}.domain.com").
   Path("/articles/{category}/{id:[0-9]+}").
+  Queries("filter", "{filter}").
   HandlerFunc(ArticleHandler).
   Name("article")
 
-// url.String() will be "http://news.domain.com/articles/technology/42"
+// url.String() will be "http://news.domain.com/articles/technology/42?filter=gorilla"
 url, err := r.Get("article").URL("subdomain", "news",
                                  "category", "technology",
-                                 "id", "42")
+                                 "id", "42",
+                                 "filter", "gorilla")
 ```
 
 All variables defined in the route are required, and their values must conform to the corresponding patterns. These requirements guarantee that a generated URL will always match a registered route -- the only exception is for explicitly defined "build-only" routes which never match.
@@ -319,6 +286,337 @@ url, err := r.Get("article").URL("subdomain", "news",
                                  "id", "42")
 ```
 
+### Walking Routes
+
+The `Walk` function on `mux.Router` can be used to visit all of the routes that are registered on a router. For example,
+the following prints all of the registered routes:
+
+```go
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/gorilla/mux"
+)
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	return
+}
+
+func main() {
+	r := mux.NewRouter()
+	r.HandleFunc("/", handler)
+	r.HandleFunc("/products", handler).Methods("POST")
+	r.HandleFunc("/articles", handler).Methods("GET")
+	r.HandleFunc("/articles/{id}", handler).Methods("GET", "PUT")
+	r.HandleFunc("/authors", handler).Queries("surname", "{surname}")
+	err := r.Walk(func(route *mux.Route, router *mux.Router, ancestors []*mux.Route) error {
+		pathTemplate, err := route.GetPathTemplate()
+		if err == nil {
+			fmt.Println("ROUTE:", pathTemplate)
+		}
+		pathRegexp, err := route.GetPathRegexp()
+		if err == nil {
+			fmt.Println("Path regexp:", pathRegexp)
+		}
+		queriesTemplates, err := route.GetQueriesTemplates()
+		if err == nil {
+			fmt.Println("Queries templates:", strings.Join(queriesTemplates, ","))
+		}
+		queriesRegexps, err := route.GetQueriesRegexp()
+		if err == nil {
+			fmt.Println("Queries regexps:", strings.Join(queriesRegexps, ","))
+		}
+		methods, err := route.GetMethods()
+		if err == nil {
+			fmt.Println("Methods:", strings.Join(methods, ","))
+		}
+		fmt.Println()
+		return nil
+	})
+
+	if err != nil {
+		fmt.Println(err)
+	}
+
+	http.Handle("/", r)
+}
+```
+
+### Graceful Shutdown
+
+Go 1.8 introduced the ability to [gracefully shutdown](https://golang.org/doc/go1.8#http_shutdown) a `*http.Server`. Here's how to do that alongside `mux`:
+
+```go
+package main
+
+import (
+    "context"
+    "flag"
+    "log"
+    "net/http"
+    "os"
+    "os/signal"
+    "time"
+
+    "github.com/gorilla/mux"
+)
+
+func main() {
+    var wait time.Duration
+    flag.DurationVar(&wait, "graceful-timeout", time.Second * 15, "the duration for which the server gracefully wait for existing connections to finish - e.g. 15s or 1m")
+    flag.Parse()
+
+    r := mux.NewRouter()
+    // Add your routes as needed
+
+    srv := &http.Server{
+        Addr:         "0.0.0.0:8080",
+        // Good practice to set timeouts to avoid Slowloris attacks.
+        WriteTimeout: time.Second * 15,
+        ReadTimeout:  time.Second * 15,
+        IdleTimeout:  time.Second * 60,
+        Handler: r, // Pass our instance of gorilla/mux in.
+    }
+
+    // Run our server in a goroutine so that it doesn't block.
+    go func() {
+        if err := srv.ListenAndServe(); err != nil {
+            log.Println(err)
+        }
+    }()
+
+    c := make(chan os.Signal, 1)
+    // We'll accept graceful shutdowns when quit via SIGINT (Ctrl+C)
+    // SIGKILL, SIGQUIT or SIGTERM (Ctrl+/) will not be caught.
+    signal.Notify(c, os.Interrupt)
+
+    // Block until we receive our signal.
+    <-c
+
+    // Create a deadline to wait for.
+    ctx, cancel := context.WithTimeout(context.Background(), wait)
+    defer cancel()
+    // Doesn't block if no connections, but will otherwise wait
+    // until the timeout deadline.
+    srv.Shutdown(ctx)
+    // Optionally, you could run srv.Shutdown in a goroutine and block on
+    // <-ctx.Done() if your application should wait for other services
+    // to finalize based on context cancellation.
+    log.Println("shutting down")
+    os.Exit(0)
+}
+```
+
+### Middleware
+
+Mux supports the addition of middlewares to a [Router](https://godoc.org/github.com/gorilla/mux#Router), which are executed in the order they are added if a match is found, including its subrouters.
+Middlewares are (typically) small pieces of code which take one request, do something with it, and pass it down to another middleware or the final handler. Some common use cases for middleware are request logging, header manipulation, or `ResponseWriter` hijacking.
+
+Mux middlewares are defined using the de facto standard type:
+
+```go
+type MiddlewareFunc func(http.Handler) http.Handler
+```
+
+Typically, the returned handler is a closure which does something with the http.ResponseWriter and http.Request passed to it, and then calls the handler passed as parameter to the MiddlewareFunc. This takes advantage of closures being able access variables from the context where they are created, while retaining the signature enforced by the receivers.
+
+A very basic middleware which logs the URI of the request being handled could be written as:
+
+```go
+func loggingMiddleware(next http.Handler) http.Handler {
+    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+        // Do stuff here
+        log.Println(r.RequestURI)
+        // Call the next handler, which can be another middleware in the chain, or the final handler.
+        next.ServeHTTP(w, r)
+    })
+}
+```
+
+Middlewares can be added to a router using `Router.Use()`:
+
+```go
+r := mux.NewRouter()
+r.HandleFunc("/", handler)
+r.Use(loggingMiddleware)
+```
+
+A more complex authentication middleware, which maps session token to users, could be written as:
+
+```go
+// Define our struct
+type authenticationMiddleware struct {
+	tokenUsers map[string]string
+}
+
+// Initialize it somewhere
+func (amw *authenticationMiddleware) Populate() {
+	amw.tokenUsers["00000000"] = "user0"
+	amw.tokenUsers["aaaaaaaa"] = "userA"
+	amw.tokenUsers["05f717e5"] = "randomUser"
+	amw.tokenUsers["deadbeef"] = "user0"
+}
+
+// Middleware function, which will be called for each request
+func (amw *authenticationMiddleware) Middleware(next http.Handler) http.Handler {
+    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+        token := r.Header.Get("X-Session-Token")
+
+        if user, found := amw.tokenUsers[token]; found {
+        	// We found the token in our map
+        	log.Printf("Authenticated user %s\n", user)
+        	// Pass down the request to the next middleware (or final handler)
+        	next.ServeHTTP(w, r)
+        } else {
+        	// Write an error and stop the handler chain
+        	http.Error(w, "Forbidden", http.StatusForbidden)
+        }
+    })
+}
+```
+
+```go
+r := mux.NewRouter()
+r.HandleFunc("/", handler)
+
+amw := authenticationMiddleware{}
+amw.Populate()
+
+r.Use(amw.Middleware)
+```
+
+Note: The handler chain will be stopped if your middleware doesn't call `next.ServeHTTP()` with the corresponding parameters. This can be used to abort a request if the middleware writer wants to. Middlewares _should_ write to `ResponseWriter` if they _are_ going to terminate the request, and they _should not_ write to `ResponseWriter` if they _are not_ going to terminate it.
+
+### Testing Handlers
+
+Testing handlers in a Go web application is straightforward, and _mux_ doesn't complicate this any further. Given two files: `endpoints.go` and `endpoints_test.go`, here's how we'd test an application using _mux_.
+
+First, our simple HTTP handler:
+
+```go
+// endpoints.go
+package main
+
+func HealthCheckHandler(w http.ResponseWriter, r *http.Request) {
+    // A very simple health check.
+    w.WriteHeader(http.StatusOK)
+    w.Header().Set("Content-Type", "application/json")
+
+    // In the future we could report back on the status of our DB, or our cache
+    // (e.g. Redis) by performing a simple PING, and include them in the response.
+    io.WriteString(w, `{"alive": true}`)
+}
+
+func main() {
+    r := mux.NewRouter()
+    r.HandleFunc("/health", HealthCheckHandler)
+
+    log.Fatal(http.ListenAndServe("localhost:8080", r))
+}
+```
+
+Our test code:
+
+```go
+// endpoints_test.go
+package main
+
+import (
+    "net/http"
+    "net/http/httptest"
+    "testing"
+)
+
+func TestHealthCheckHandler(t *testing.T) {
+    // Create a request to pass to our handler. We don't have any query parameters for now, so we'll
+    // pass 'nil' as the third parameter.
+    req, err := http.NewRequest("GET", "/health", nil)
+    if err != nil {
+        t.Fatal(err)
+    }
+
+    // We create a ResponseRecorder (which satisfies http.ResponseWriter) to record the response.
+    rr := httptest.NewRecorder()
+    handler := http.HandlerFunc(HealthCheckHandler)
+
+    // Our handlers satisfy http.Handler, so we can call their ServeHTTP method
+    // directly and pass in our Request and ResponseRecorder.
+    handler.ServeHTTP(rr, req)
+
+    // Check the status code is what we expect.
+    if status := rr.Code; status != http.StatusOK {
+        t.Errorf("handler returned wrong status code: got %v want %v",
+            status, http.StatusOK)
+    }
+
+    // Check the response body is what we expect.
+    expected := `{"alive": true}`
+    if rr.Body.String() != expected {
+        t.Errorf("handler returned unexpected body: got %v want %v",
+            rr.Body.String(), expected)
+    }
+}
+```
+
+In the case that our routes have [variables](#examples), we can pass those in the request. We could write
+[table-driven tests](https://dave.cheney.net/2013/06/09/writing-table-driven-tests-in-go) to test multiple
+possible route variables as needed.
+
+```go
+// endpoints.go
+func main() {
+    r := mux.NewRouter()
+    // A route with a route variable:
+    r.HandleFunc("/metrics/{type}", MetricsHandler)
+
+    log.Fatal(http.ListenAndServe("localhost:8080", r))
+}
+```
+
+Our test file, with a table-driven test of `routeVariables`:
+
+```go
+// endpoints_test.go
+func TestMetricsHandler(t *testing.T) {
+    tt := []struct{
+        routeVariable string
+        shouldPass bool
+    }{
+        {"goroutines", true},
+        {"heap", true},
+        {"counters", true},
+        {"queries", true},
+        {"adhadaeqm3k", false},
+    }
+
+    for _, tc := range tt {
+        path := fmt.Sprintf("/metrics/%s", tc.routeVariable)
+        req, err := http.NewRequest("GET", path, nil)
+        if err != nil {
+            t.Fatal(err)
+        }
+
+        rr := httptest.NewRecorder()
+	
+	// Need to create a router that we can pass the request through so that the vars will be added to the context
+	router := mux.NewRouter()
+        router.HandleFunc("/metrics/{type}", MetricsHandler)
+        router.ServeHTTP(rr, req)
+
+        // In this case, our MetricsHandler returns a non-200 response
+        // for a route variable it doesn't know about.
+        if rr.Code == http.StatusOK && !tc.shouldPass {
+            t.Errorf("handler should have failed on routeVariable %s: got %v want %v",
+                tc.routeVariable, rr.Code, http.StatusOK)
+        }
+    }
+}
+```
+
 ## Full Example
 
 Here's a complete, runnable example of a small `mux` based server:
@@ -327,22 +625,22 @@ Here's a complete, runnable example of a small `mux` based server:
 package main
 
 import (
-	"net/http"
-	"log"
-	"github.com/gorilla/mux"
+    "net/http"
+    "log"
+    "github.com/gorilla/mux"
 )
 
 func YourHandler(w http.ResponseWriter, r *http.Request) {
-	w.Write([]byte("Gorilla!\n"))
+    w.Write([]byte("Gorilla!\n"))
 }
 
 func main() {
-	r := mux.NewRouter()
-	// Routes consist of a path and a handler function.
-	r.HandleFunc("/", YourHandler)
+    r := mux.NewRouter()
+    // Routes consist of a path and a handler function.
+    r.HandleFunc("/", YourHandler)
 
-	// Bind to a port and pass our router in
-	log.Fatal(http.ListenAndServe(":8000", r))
+    // Bind to a port and pass our router in
+    log.Fatal(http.ListenAndServe(":8000", r))
 }
 ```
 

doc.go

@@ -12,8 +12,8 @@ or other conditions. The main features are:
 
 	* Requests can be matched based on URL host, path, path prefix, schemes,
 	  header and query values, HTTP methods or using custom matchers.
-	* URL hosts and paths can have variables with an optional regular
-	  expression.
+	* URL hosts, paths and query values can have variables with an optional
+	  regular expression.
 	* Registered URLs can be built, or "reversed", which helps maintaining
 	  references to resources.
 	* Routes can be used as subrouters: nested routes are only tested if the
@@ -188,18 +188,20 @@ key/value pairs for the route variables. For the previous route, we would do:
 
 	"/articles/technology/42"
 
-This also works for host variables:
+This also works for host and query value variables:
 
 	r := mux.NewRouter()
 	r.Host("{subdomain}.domain.com").
 	  Path("/articles/{category}/{id:[0-9]+}").
+	  Queries("filter", "{filter}").
 	  HandlerFunc(ArticleHandler).
 	  Name("article")
 
-	// url.String() will be "http://news.domain.com/articles/technology/42"
+	// url.String() will be "http://news.domain.com/articles/technology/42?filter=gorilla"
 	url, err := r.Get("article").URL("subdomain", "news",
 	                                 "category", "technology",
-	                                 "id", "42")
+	                                 "id", "42",
+	                                 "filter", "gorilla")
 
 All variables defined in the route are required, and their values must
 conform to the corresponding patterns. These requirements guarantee that a
@@ -236,5 +238,69 @@ as well:
 	url, err := r.Get("article").URL("subdomain", "news",
 	                                 "category", "technology",
 	                                 "id", "42")
+
+Mux supports the addition of middlewares to a Router, which are executed in the order they are added if a match is found, including its subrouters. Middlewares are (typically) small pieces of code which take one request, do something with it, and pass it down to another middleware or the final handler. Some common use cases for middleware are request logging, header manipulation, or ResponseWriter hijacking.
+
+	type MiddlewareFunc func(http.Handler) http.Handler
+
+Typically, the returned handler is a closure which does something with the http.ResponseWriter and http.Request passed to it, and then calls the handler passed as parameter to the MiddlewareFunc (closures can access variables from the context where they are created).
+
+A very basic middleware which logs the URI of the request being handled could be written as:
+
+	func simpleMw(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// Do stuff here
+			log.Println(r.RequestURI)
+			// Call the next handler, which can be another middleware in the chain, or the final handler.
+			next.ServeHTTP(w, r)
+		})
+	}
+
+Middlewares can be added to a router using `Router.Use()`:
+
+	r := mux.NewRouter()
+	r.HandleFunc("/", handler)
+	r.Use(simpleMw)
+
+A more complex authentication middleware, which maps session token to users, could be written as:
+
+	// Define our struct
+	type authenticationMiddleware struct {
+		tokenUsers map[string]string
+	}
+
+	// Initialize it somewhere
+	func (amw *authenticationMiddleware) Populate() {
+		amw.tokenUsers["00000000"] = "user0"
+		amw.tokenUsers["aaaaaaaa"] = "userA"
+		amw.tokenUsers["05f717e5"] = "randomUser"
+		amw.tokenUsers["deadbeef"] = "user0"
+	}
+
+	// Middleware function, which will be called for each request
+	func (amw *authenticationMiddleware) Middleware(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			token := r.Header.Get("X-Session-Token")
+
+			if user, found := amw.tokenUsers[token]; found {
+				// We found the token in our map
+				log.Printf("Authenticated user %s\n", user)
+				next.ServeHTTP(w, r)
+			} else {
+				http.Error(w, "Forbidden", http.StatusForbidden)
+			}
+		})
+	}
+
+	r := mux.NewRouter()
+	r.HandleFunc("/", handler)
+
+	amw := authenticationMiddleware{}
+	amw.Populate()
+
+	r.Use(amw.Middleware)
+
+Note: The handler chain will be stopped if your middleware doesn't call `next.ServeHTTP()` with the corresponding parameters. This can be used to abort a request if the middleware writer wants to.
+
 */
 package mux

example_authentication_middleware_test.go

@@ -0,0 +1,46 @@
+package mux_test
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/gorilla/mux"
+)
+
+// Define our struct
+type authenticationMiddleware struct {
+	tokenUsers map[string]string
+}
+
+// Initialize it somewhere
+func (amw *authenticationMiddleware) Populate() {
+	amw.tokenUsers["00000000"] = "user0"
+	amw.tokenUsers["aaaaaaaa"] = "userA"
+	amw.tokenUsers["05f717e5"] = "randomUser"
+	amw.tokenUsers["deadbeef"] = "user0"
+}
+
+// Middleware function, which will be called for each request
+func (amw *authenticationMiddleware) Middleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		token := r.Header.Get("X-Session-Token")
+
+		if user, found := amw.tokenUsers[token]; found {
+			// We found the token in our map
+			log.Printf("Authenticated user %s\n", user)
+			next.ServeHTTP(w, r)
+		} else {
+			http.Error(w, "Forbidden", http.StatusForbidden)
+		}
+	})
+}
+
+func Example_authenticationMiddleware() {
+	r := mux.NewRouter()
+	r.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		// Do something here
+	})
+	amw := authenticationMiddleware{}
+	amw.Populate()
+	r.Use(amw.Middleware)
+}

example_route_test.go

@@ -0,0 +1,51 @@
+package mux_test
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/gorilla/mux"
+)
+
+// This example demonstrates setting a regular expression matcher for
+// the header value. A plain word will match any value that contains a
+// matching substring as if the pattern was wrapped with `.*`.
+func ExampleRoute_HeadersRegexp() {
+	r := mux.NewRouter()
+	route := r.NewRoute().HeadersRegexp("Accept", "html")
+
+	req1, _ := http.NewRequest("GET", "example.com", nil)
+	req1.Header.Add("Accept", "text/plain")
+	req1.Header.Add("Accept", "text/html")
+
+	req2, _ := http.NewRequest("GET", "example.com", nil)
+	req2.Header.Set("Accept", "application/xhtml+xml")
+
+	matchInfo := &mux.RouteMatch{}
+	fmt.Printf("Match: %v %q\n", route.Match(req1, matchInfo), req1.Header["Accept"])
+	fmt.Printf("Match: %v %q\n", route.Match(req2, matchInfo), req2.Header["Accept"])
+	// Output:
+	// Match: true ["text/plain" "text/html"]
+	// Match: true ["application/xhtml+xml"]
+}
+
+// This example demonstrates setting a strict regular expression matcher
+// for the header value. Using the start and end of string anchors, the
+// value must be an exact match.
+func ExampleRoute_HeadersRegexp_exactMatch() {
+	r := mux.NewRouter()
+	route := r.NewRoute().HeadersRegexp("Origin", "^https://example.co$")
+
+	yes, _ := http.NewRequest("GET", "example.co", nil)
+	yes.Header.Set("Origin", "https://example.co")
+
+	no, _ := http.NewRequest("GET", "example.co.uk", nil)
+	no.Header.Set("Origin", "https://example.co.uk")
+
+	matchInfo := &mux.RouteMatch{}
+	fmt.Printf("Match: %v %q\n", route.Match(yes, matchInfo), yes.Header["Origin"])
+	fmt.Printf("Match: %v %q\n", route.Match(no, matchInfo), no.Header["Origin"])
+	// Output:
+	// Match: true ["https://example.co"]
+	// Match: false ["https://example.co.uk"]
+}

middleware.go

@@ -0,0 +1,72 @@
+package mux
+
+import (
+	"net/http"
+	"strings"
+)
+
+// MiddlewareFunc is a function which receives an http.Handler and returns another http.Handler.
+// Typically, the returned handler is a closure which does something with the http.ResponseWriter and http.Request passed
+// to it, and then calls the handler passed as parameter to the MiddlewareFunc.
+type MiddlewareFunc func(http.Handler) http.Handler
+
+// middleware interface is anything which implements a MiddlewareFunc named Middleware.
+type middleware interface {
+	Middleware(handler http.Handler) http.Handler
+}
+
+// Middleware allows MiddlewareFunc to implement the middleware interface.
+func (mw MiddlewareFunc) Middleware(handler http.Handler) http.Handler {
+	return mw(handler)
+}
+
+// Use appends a MiddlewareFunc to the chain. Middleware can be used to intercept or otherwise modify requests and/or responses, and are executed in the order that they are applied to the Router.
+func (r *Router) Use(mwf ...MiddlewareFunc) {
+	for _, fn := range mwf {
+		r.middlewares = append(r.middlewares, fn)
+	}
+}
+
+// useInterface appends a middleware to the chain. Middleware can be used to intercept or otherwise modify requests and/or responses, and are executed in the order that they are applied to the Router.
+func (r *Router) useInterface(mw middleware) {
+	r.middlewares = append(r.middlewares, mw)
+}
+
+// CORSMethodMiddleware sets the Access-Control-Allow-Methods response header
+// on a request, by matching routes based only on paths. It also handles
+// OPTIONS requests, by settings Access-Control-Allow-Methods, and then
+// returning without calling the next http handler.
+func CORSMethodMiddleware(r *Router) MiddlewareFunc {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+			var allMethods []string
+
+			err := r.Walk(func(route *Route, _ *Router, _ []*Route) error {
+				for _, m := range route.matchers {
+					if _, ok := m.(*routeRegexp); ok {
+						if m.Match(req, &RouteMatch{}) {
+							methods, err := route.GetMethods()
+							if err != nil {
+								return err
+							}
+
+							allMethods = append(allMethods, methods...)
+						}
+						break
+					}
+				}
+				return nil
+			})
+
+			if err == nil {
+				w.Header().Set("Access-Control-Allow-Methods", strings.Join(append(allMethods, "OPTIONS"), ","))
+
+				if req.Method == "OPTIONS" {
+					return
+				}
+			}
+
+			next.ServeHTTP(w, req)
+		})
+	}
+}

middleware_test.go

@@ -0,0 +1,377 @@
+package mux
+
+import (
+	"bytes"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+type testMiddleware struct {
+	timesCalled uint
+}
+
+func (tm *testMiddleware) Middleware(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		tm.timesCalled++
+		h.ServeHTTP(w, r)
+	})
+}
+
+func dummyHandler(w http.ResponseWriter, r *http.Request) {}
+
+func TestMiddlewareAdd(t *testing.T) {
+	router := NewRouter()
+	router.HandleFunc("/", dummyHandler).Methods("GET")
+
+	mw := &testMiddleware{}
+
+	router.useInterface(mw)
+	if len(router.middlewares) != 1 || router.middlewares[0] != mw {
+		t.Fatal("Middleware was not added correctly")
+	}
+
+	router.Use(mw.Middleware)
+	if len(router.middlewares) != 2 {
+		t.Fatal("MiddlewareFunc method was not added correctly")
+	}
+
+	banalMw := func(handler http.Handler) http.Handler {
+		return handler
+	}
+	router.Use(banalMw)
+	if len(router.middlewares) != 3 {
+		t.Fatal("MiddlewareFunc method was not added correctly")
+	}
+}
+
+func TestMiddleware(t *testing.T) {
+	router := NewRouter()
+	router.HandleFunc("/", dummyHandler).Methods("GET")
+
+	mw := &testMiddleware{}
+	router.useInterface(mw)
+
+	rw := NewRecorder()
+	req := newRequest("GET", "/")
+
+	// Test regular middleware call
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 1 {
+		t.Fatalf("Expected %d calls, but got only %d", 1, mw.timesCalled)
+	}
+
+	// Middleware should not be called for 404
+	req = newRequest("GET", "/not/found")
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 1 {
+		t.Fatalf("Expected %d calls, but got only %d", 1, mw.timesCalled)
+	}
+
+	// Middleware should not be called if there is a method mismatch
+	req = newRequest("POST", "/")
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 1 {
+		t.Fatalf("Expected %d calls, but got only %d", 1, mw.timesCalled)
+	}
+
+	// Add the middleware again as function
+	router.Use(mw.Middleware)
+	req = newRequest("GET", "/")
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 3 {
+		t.Fatalf("Expected %d calls, but got only %d", 3, mw.timesCalled)
+	}
+
+}
+
+func TestMiddlewareSubrouter(t *testing.T) {
+	router := NewRouter()
+	router.HandleFunc("/", dummyHandler).Methods("GET")
+
+	subrouter := router.PathPrefix("/sub").Subrouter()
+	subrouter.HandleFunc("/x", dummyHandler).Methods("GET")
+
+	mw := &testMiddleware{}
+	subrouter.useInterface(mw)
+
+	rw := NewRecorder()
+	req := newRequest("GET", "/")
+
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 0 {
+		t.Fatalf("Expected %d calls, but got only %d", 0, mw.timesCalled)
+	}
+
+	req = newRequest("GET", "/sub/")
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 0 {
+		t.Fatalf("Expected %d calls, but got only %d", 0, mw.timesCalled)
+	}
+
+	req = newRequest("GET", "/sub/x")
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 1 {
+		t.Fatalf("Expected %d calls, but got only %d", 1, mw.timesCalled)
+	}
+
+	req = newRequest("GET", "/sub/not/found")
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 1 {
+		t.Fatalf("Expected %d calls, but got only %d", 1, mw.timesCalled)
+	}
+
+	router.useInterface(mw)
+
+	req = newRequest("GET", "/")
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 2 {
+		t.Fatalf("Expected %d calls, but got only %d", 2, mw.timesCalled)
+	}
+
+	req = newRequest("GET", "/sub/x")
+	router.ServeHTTP(rw, req)
+	if mw.timesCalled != 4 {
+		t.Fatalf("Expected %d calls, but got only %d", 4, mw.timesCalled)
+	}
+}
+
+func TestMiddlewareExecution(t *testing.T) {
+	mwStr := []byte("Middleware\n")
+	handlerStr := []byte("Logic\n")
+
+	router := NewRouter()
+	router.HandleFunc("/", func(w http.ResponseWriter, e *http.Request) {
+		w.Write(handlerStr)
+	})
+
+	rw := NewRecorder()
+	req := newRequest("GET", "/")
+
+	// Test handler-only call
+	router.ServeHTTP(rw, req)
+
+	if bytes.Compare(rw.Body.Bytes(), handlerStr) != 0 {
+		t.Fatal("Handler response is not what it should be")
+	}
+
+	// Test middleware call
+	rw = NewRecorder()
+
+	router.Use(func(h http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Write(mwStr)
+			h.ServeHTTP(w, r)
+		})
+	})
+
+	router.ServeHTTP(rw, req)
+	if bytes.Compare(rw.Body.Bytes(), append(mwStr, handlerStr...)) != 0 {
+		t.Fatal("Middleware + handler response is not what it should be")
+	}
+}
+
+func TestMiddlewareNotFound(t *testing.T) {
+	mwStr := []byte("Middleware\n")
+	handlerStr := []byte("Logic\n")
+
+	router := NewRouter()
+	router.HandleFunc("/", func(w http.ResponseWriter, e *http.Request) {
+		w.Write(handlerStr)
+	})
+	router.Use(func(h http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Write(mwStr)
+			h.ServeHTTP(w, r)
+		})
+	})
+
+	// Test not found call with default handler
+	rw := NewRecorder()
+	req := newRequest("GET", "/notfound")
+
+	router.ServeHTTP(rw, req)
+	if bytes.Contains(rw.Body.Bytes(), mwStr) {
+		t.Fatal("Middleware was called for a 404")
+	}
+
+	// Test not found call with custom handler
+	rw = NewRecorder()
+	req = newRequest("GET", "/notfound")
+
+	router.NotFoundHandler = http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		rw.Write([]byte("Custom 404 handler"))
+	})
+	router.ServeHTTP(rw, req)
+
+	if bytes.Contains(rw.Body.Bytes(), mwStr) {
+		t.Fatal("Middleware was called for a custom 404")
+	}
+}
+
+func TestMiddlewareMethodMismatch(t *testing.T) {
+	mwStr := []byte("Middleware\n")
+	handlerStr := []byte("Logic\n")
+
+	router := NewRouter()
+	router.HandleFunc("/", func(w http.ResponseWriter, e *http.Request) {
+		w.Write(handlerStr)
+	}).Methods("GET")
+
+	router.Use(func(h http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Write(mwStr)
+			h.ServeHTTP(w, r)
+		})
+	})
+
+	// Test method mismatch
+	rw := NewRecorder()
+	req := newRequest("POST", "/")
+
+	router.ServeHTTP(rw, req)
+	if bytes.Contains(rw.Body.Bytes(), mwStr) {
+		t.Fatal("Middleware was called for a method mismatch")
+	}
+
+	// Test not found call
+	rw = NewRecorder()
+	req = newRequest("POST", "/")
+
+	router.MethodNotAllowedHandler = http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		rw.Write([]byte("Method not allowed"))
+	})
+	router.ServeHTTP(rw, req)
+
+	if bytes.Contains(rw.Body.Bytes(), mwStr) {
+		t.Fatal("Middleware was called for a method mismatch")
+	}
+}
+
+func TestMiddlewareNotFoundSubrouter(t *testing.T) {
+	mwStr := []byte("Middleware\n")
+	handlerStr := []byte("Logic\n")
+
+	router := NewRouter()
+	router.HandleFunc("/", func(w http.ResponseWriter, e *http.Request) {
+		w.Write(handlerStr)
+	})
+
+	subrouter := router.PathPrefix("/sub/").Subrouter()
+	subrouter.HandleFunc("/", func(w http.ResponseWriter, e *http.Request) {
+		w.Write(handlerStr)
+	})
+
+	router.Use(func(h http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Write(mwStr)
+			h.ServeHTTP(w, r)
+		})
+	})
+
+	// Test not found call for default handler
+	rw := NewRecorder()
+	req := newRequest("GET", "/sub/notfound")
+
+	router.ServeHTTP(rw, req)
+	if bytes.Contains(rw.Body.Bytes(), mwStr) {
+		t.Fatal("Middleware was called for a 404")
+	}
+
+	// Test not found call with custom handler
+	rw = NewRecorder()
+	req = newRequest("GET", "/sub/notfound")
+
+	subrouter.NotFoundHandler = http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		rw.Write([]byte("Custom 404 handler"))
+	})
+	router.ServeHTTP(rw, req)
+
+	if bytes.Contains(rw.Body.Bytes(), mwStr) {
+		t.Fatal("Middleware was called for a custom 404")
+	}
+}
+
+func TestMiddlewareMethodMismatchSubrouter(t *testing.T) {
+	mwStr := []byte("Middleware\n")
+	handlerStr := []byte("Logic\n")
+
+	router := NewRouter()
+	router.HandleFunc("/", func(w http.ResponseWriter, e *http.Request) {
+		w.Write(handlerStr)
+	})
+
+	subrouter := router.PathPrefix("/sub/").Subrouter()
+	subrouter.HandleFunc("/", func(w http.ResponseWriter, e *http.Request) {
+		w.Write(handlerStr)
+	}).Methods("GET")
+
+	router.Use(func(h http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Write(mwStr)
+			h.ServeHTTP(w, r)
+		})
+	})
+
+	// Test method mismatch without custom handler
+	rw := NewRecorder()
+	req := newRequest("POST", "/sub/")
+
+	router.ServeHTTP(rw, req)
+	if bytes.Contains(rw.Body.Bytes(), mwStr) {
+		t.Fatal("Middleware was called for a method mismatch")
+	}
+
+	// Test method mismatch with custom handler
+	rw = NewRecorder()
+	req = newRequest("POST", "/sub/")
+
+	router.MethodNotAllowedHandler = http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		rw.Write([]byte("Method not allowed"))
+	})
+	router.ServeHTTP(rw, req)
+
+	if bytes.Contains(rw.Body.Bytes(), mwStr) {
+		t.Fatal("Middleware was called for a method mismatch")
+	}
+}
+
+func TestCORSMethodMiddleware(t *testing.T) {
+	router := NewRouter()
+
+	cases := []struct {
+		path                   string
+		response               string
+		method                 string
+		testURL                string
+		expectedAllowedMethods string
+	}{
+		{"/g/{o}", "a", "POST", "/g/asdf", "POST,PUT,GET,OPTIONS"},
+		{"/g/{o}", "b", "PUT", "/g/bla", "POST,PUT,GET,OPTIONS"},
+		{"/g/{o}", "c", "GET", "/g/orilla", "POST,PUT,GET,OPTIONS"},
+		{"/g", "d", "POST", "/g", "POST,OPTIONS"},
+	}
+
+	for _, tt := range cases {
+		router.HandleFunc(tt.path, stringHandler(tt.response)).Methods(tt.method)
+	}
+
+	router.Use(CORSMethodMiddleware(router))
+
+	for _, tt := range cases {
+		rr := httptest.NewRecorder()
+		req := newRequest(tt.method, tt.testURL)
+
+		router.ServeHTTP(rr, req)
+
+		if rr.Body.String() != tt.response {
+			t.Errorf("Expected body '%s', found '%s'", tt.response, rr.Body.String())
+		}
+
+		allowedMethods := rr.HeaderMap.Get("Access-Control-Allow-Methods")
+
+		if allowedMethods != tt.expectedAllowedMethods {
+			t.Errorf("Expected Access-Control-Allow-Methods '%s', found '%s'", tt.expectedAllowedMethods, allowedMethods)
+		}
+	}
+}

mux.go

@@ -10,7 +10,14 @@ import (
 	"net/http"
 	"path"
 	"regexp"
-	"strings"
+)
+
+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.
@@ -39,6 +46,10 @@ func NewRouter() *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.
@@ -55,21 +66,51 @@ type Router struct {
 	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 matches registered routes against the request.
+// 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
 }
 
@@ -81,7 +122,7 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	if !r.skipClean {
 		path := req.URL.Path
 		if r.useEncodedPath {
-			path = getPath(req)
+			path = req.URL.EscapedPath()
 		}
 		// Clean path to canonical form and redirect.
 		if p := cleanPath(path); p != path {
@@ -105,12 +146,19 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		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)
 }
 
@@ -128,13 +176,18 @@ func (r *Router) GetRoute(name string) *Route {
 // 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 redirect
+// 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
@@ -160,10 +213,6 @@ func (r *Router) SkipClean(value bool) *Router {
 // 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".
-// This behavior has the drawback of needing to match routes against
-// r.RequestURI instead of r.URL.Path. Any modifications (such as http.StripPrefix)
-// to r.URL.Path will not affect routing when this flag is on and thus may
-// induce unintended behavior.
 //
 // 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"
@@ -176,6 +225,13 @@ func (r *Router) UseEncodedPath() *Router {
 // 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 {
@@ -299,10 +355,6 @@ type WalkFunc func(route *Route, router *Router, ancestors []*Route) error
 
 func (r *Router) walk(walkFn WalkFunc, ancestors []*Route) error {
 	for _, t := range r.routes {
-		if t.regexp == nil || t.regexp.path == nil || t.regexp.path.template == "" {
-			continue
-		}
-
 		err := walkFn(t, r, ancestors)
 		if err == SkipRouter {
 			continue
@@ -312,10 +364,12 @@ func (r *Router) walk(walkFn WalkFunc, ancestors []*Route) error {
 		}
 		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 {
@@ -339,6 +393,11 @@ 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
@@ -380,28 +439,6 @@ func setCurrentRoute(r *http.Request, val interface{}) *http.Request {
 // Helpers
 // ----------------------------------------------------------------------------
 
-// getPath returns the escaped path if possible; doing what URL.EscapedPath()
-// which was added in go1.5 does
-func getPath(req *http.Request) string {
-	if req.RequestURI != "" {
-		// Extract the path from RequestURI (which is escaped unlike URL.Path)
-		// as detailed here as detailed in https://golang.org/pkg/net/url/#URL
-		// for < 1.5 server side workaround
-		// http://localhost/path/here?v=1 -> /path/here
-		path := req.RequestURI
-		path = strings.TrimPrefix(path, req.URL.Scheme+`://`)
-		path = strings.TrimPrefix(path, req.URL.Host)
-		if i := strings.LastIndex(path, "?"); i > -1 {
-			path = path[:i]
-		}
-		if i := strings.LastIndex(path, "#"); i > -1 {
-			path = path[:i]
-		}
-		return path
-	}
-	return req.URL.Path
-}
-
 // cleanPath returns the canonical path for p, eliminating . and .. elements.
 // Borrowed from the net/http package.
 func cleanPath(p string) string {
@@ -458,7 +495,7 @@ func mapFromPairsToString(pairs ...string) (map[string]string, error) {
 	return m, nil
 }
 
-// mapFromPairsToRegex converts variadic string paramers to a
+// mapFromPairsToRegex converts variadic string parameters to a
 // string to regex map.
 func mapFromPairsToRegex(pairs ...string) (map[string]*regexp.Regexp, error) {
 	length, err := checkPairs(pairs...)
@@ -540,3 +577,12 @@ func matchMapWithRegex(toCheck map[string]*regexp.Regexp, toMatch map[string][]s
 	}
 	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) }

old_test.go

@@ -121,12 +121,7 @@ func TestRouteMatchers(t *testing.T) {
 		var routeMatch RouteMatch
 		matched := router.Match(request, &routeMatch)
 		if matched != shouldMatch {
-			// Need better messages. :)
-			if matched {
-				t.Errorf("Should match.")
-			} else {
-				t.Errorf("Should not match.")
-			}
+			t.Errorf("Expected: %v\nGot: %v\nRequest: %v %v", shouldMatch, matched, request.Method, url)
 		}
 
 		if matched {
@@ -188,7 +183,6 @@ func TestRouteMatchers(t *testing.T) {
 	match(true)
 
 	// 2nd route --------------------------------------------------------------
-
 	// Everything match.
 	reset2()
 	match(true)
@@ -687,7 +681,7 @@ func TestNewRegexp(t *testing.T) {
 	}
 
 	for pattern, paths := range tests {
-		p, _ = newRouteRegexp(pattern, false, false, false, false, false)
+		p, _ = newRouteRegexp(pattern, regexpTypePath, routeRegexpOptions{})
 		for path, result := range paths {
 			matches = p.regexp.FindStringSubmatch(path)
 			if result == nil {

regexp.go

@@ -14,6 +14,20 @@ import (
 	"strings"
 )
 
+type routeRegexpOptions struct {
+	strictSlash    bool
+	useEncodedPath bool
+}
+
+type regexpType int
+
+const (
+	regexpTypePath   regexpType = 0
+	regexpTypeHost   regexpType = 1
+	regexpTypePrefix regexpType = 2
+	regexpTypeQuery  regexpType = 3
+)
+
 // newRouteRegexp parses a route template and returns a routeRegexp,
 // used to match a host, a path or a query string.
 //
@@ -24,7 +38,7 @@ import (
 // Previously we accepted only Python-like identifiers for variable
 // names ([a-zA-Z_][a-zA-Z0-9_]*), but currently the only restriction is that
 // name and pattern can't be empty, and names can't contain a colon.
-func newRouteRegexp(tpl string, matchHost, matchPrefix, matchQuery, strictSlash, useEncodedPath bool) (*routeRegexp, error) {
+func newRouteRegexp(tpl string, typ regexpType, options routeRegexpOptions) (*routeRegexp, error) {
 	// Check if it is well-formed.
 	idxs, errBraces := braceIndices(tpl)
 	if errBraces != nil {
@@ -34,19 +48,18 @@ func newRouteRegexp(tpl string, matchHost, matchPrefix, matchQuery, strictSlash,
 	template := tpl
 	// Now let's parse it.
 	defaultPattern := "[^/]+"
-	if matchQuery {
-		defaultPattern = "[^?&]*"
-	} else if matchHost {
+	if typ == regexpTypeQuery {
+		defaultPattern = ".*"
+	} else if typ == regexpTypeHost {
 		defaultPattern = "[^.]+"
-		matchPrefix = false
 	}
 	// Only match strict slash if not matching
-	if matchPrefix || matchHost || matchQuery {
-		strictSlash = false
+	if typ != regexpTypePath {
+		options.strictSlash = false
 	}
 	// Set a flag for strictSlash.
 	endSlash := false
-	if strictSlash && strings.HasSuffix(tpl, "/") {
+	if options.strictSlash && strings.HasSuffix(tpl, "/") {
 		tpl = tpl[:len(tpl)-1]
 		endSlash = true
 	}
@@ -88,16 +101,16 @@ func newRouteRegexp(tpl string, matchHost, matchPrefix, matchQuery, strictSlash,
 	// Add the remaining.
 	raw := tpl[end:]
 	pattern.WriteString(regexp.QuoteMeta(raw))
-	if strictSlash {
+	if options.strictSlash {
 		pattern.WriteString("[/]?")
 	}
-	if matchQuery {
+	if typ == regexpTypeQuery {
 		// Add the default pattern if the query value is empty
 		if queryVal := strings.SplitN(template, "=", 2)[1]; queryVal == "" {
 			pattern.WriteString(defaultPattern)
 		}
 	}
-	if !matchPrefix {
+	if typ != regexpTypePrefix {
 		pattern.WriteByte('$')
 	}
 	reverse.WriteString(raw)
@@ -118,15 +131,13 @@ func newRouteRegexp(tpl string, matchHost, matchPrefix, matchQuery, strictSlash,
 
 	// Done!
 	return &routeRegexp{
-		template:       template,
-		matchHost:      matchHost,
-		matchQuery:     matchQuery,
-		strictSlash:    strictSlash,
-		useEncodedPath: useEncodedPath,
-		regexp:         reg,
-		reverse:        reverse.String(),
-		varsN:          varsN,
-		varsR:          varsR,
+		template:   template,
+		regexpType: typ,
+		options:    options,
+		regexp:     reg,
+		reverse:    reverse.String(),
+		varsN:      varsN,
+		varsR:      varsR,
 	}, nil
 }
 
@@ -135,15 +146,10 @@ func newRouteRegexp(tpl string, matchHost, matchPrefix, matchQuery, strictSlash,
 type routeRegexp struct {
 	// The unmodified template.
 	template string
-	// True for host match, false for path or query string match.
-	matchHost bool
-	// True for query string match, false for path and host match.
-	matchQuery bool
-	// The strictSlash value defined on the route, but disabled if PathPrefix was used.
-	strictSlash bool
-	// Determines whether to use encoded path from getPath function or unencoded
-	// req.URL.Path for path matching
-	useEncodedPath bool
+	// The type of match
+	regexpType regexpType
+	// Options for matching
+	options routeRegexpOptions
 	// Expanded regexp.
 	regexp *regexp.Regexp
 	// Reverse template.
@@ -156,13 +162,13 @@ type routeRegexp struct {
 
 // Match matches the regexp against the URL host or path.
 func (r *routeRegexp) Match(req *http.Request, match *RouteMatch) bool {
-	if !r.matchHost {
-		if r.matchQuery {
+	if r.regexpType != regexpTypeHost {
+		if r.regexpType == regexpTypeQuery {
 			return r.matchQueryString(req)
 		}
 		path := req.URL.Path
-		if r.useEncodedPath {
-			path = getPath(req)
+		if r.options.useEncodedPath {
+			path = req.URL.EscapedPath()
 		}
 		return r.regexp.MatchString(path)
 	}
@@ -178,6 +184,9 @@ func (r *routeRegexp) url(values map[string]string) (string, error) {
 		if !ok {
 			return "", fmt.Errorf("mux: missing route variable %q", v)
 		}
+		if r.regexpType == regexpTypeQuery {
+			value = url.QueryEscape(value)
+		}
 		urlValues[k] = value
 	}
 	rv := fmt.Sprintf(r.reverse, urlValues...)
@@ -200,7 +209,7 @@ func (r *routeRegexp) url(values map[string]string) (string, error) {
 // For a URL with foo=bar&baz=ding, we return only the relevant key
 // value pair for the routeRegexp.
 func (r *routeRegexp) getURLQuery(req *http.Request) string {
-	if !r.matchQuery {
+	if r.regexpType != regexpTypeQuery {
 		return ""
 	}
 	templateKey := strings.SplitN(r.template, "=", 2)[0]
@@ -269,7 +278,7 @@ func (v *routeRegexpGroup) setMatch(req *http.Request, m *RouteMatch, r *Route)
 	}
 	path := req.URL.Path
 	if r.useEncodedPath {
-		path = getPath(req)
+		path = req.URL.EscapedPath()
 	}
 	// Store path variables.
 	if v.path != nil {
@@ -277,7 +286,7 @@ func (v *routeRegexpGroup) setMatch(req *http.Request, m *RouteMatch, r *Route)
 		if len(matches) > 0 {
 			extractVars(path, matches, v.path.varsN, m.Vars)
 			// Check if we should redirect.
-			if v.path.strictSlash {
+			if v.path.options.strictSlash {
 				p1 := strings.HasSuffix(path, "/")
 				p2 := strings.HasSuffix(v.path.template, "/")
 				if p1 != p2 {

route.go

@@ -43,6 +43,8 @@ type Route struct {
 	buildVarsFunc BuildVarsFunc
 }
 
+// SkipClean reports whether path cleaning is enabled for this route via
+// Router.SkipClean.
 func (r *Route) SkipClean() bool {
 	return r.skipClean
 }
@@ -52,12 +54,33 @@ func (r *Route) Match(req *http.Request, match *RouteMatch) bool {
 	if r.buildOnly || r.err != nil {
 		return false
 	}
+
+	var matchErr error
+
 	// Match everything.
 	for _, m := range r.matchers {
 		if matched := m.Match(req, match); !matched {
+			if _, ok := m.(methodMatcher); ok {
+				matchErr = ErrMethodMismatch
+				continue
+			}
+			matchErr = nil
 			return false
 		}
 	}
+
+	if matchErr != nil {
+		match.MatchErr = matchErr
+		return false
+	}
+
+	if match.MatchErr == ErrMethodMismatch {
+		// We found a route which matches request method, clear MatchErr
+		match.MatchErr = nil
+		// Then override the mis-matched handler
+		match.Handler = r.handler
+	}
+
 	// Yay, we have a match. Let's collect some info about it.
 	if match.Route == nil {
 		match.Route = r
@@ -68,6 +91,7 @@ func (r *Route) Match(req *http.Request, match *RouteMatch) bool {
 	if match.Vars == nil {
 		match.Vars = make(map[string]string)
 	}
+
 	// Set variables.
 	if r.regexp != nil {
 		r.regexp.setMatch(req, match, r)
@@ -149,12 +173,12 @@ func (r *Route) addMatcher(m matcher) *Route {
 }
 
 // addRegexpMatcher adds a host or path matcher and builder to a route.
-func (r *Route) addRegexpMatcher(tpl string, matchHost, matchPrefix, matchQuery bool) error {
+func (r *Route) addRegexpMatcher(tpl string, typ regexpType) error {
 	if r.err != nil {
 		return r.err
 	}
 	r.regexp = r.getRegexpGroup()
-	if !matchHost && !matchQuery {
+	if typ == regexpTypePath || typ == regexpTypePrefix {
 		if len(tpl) > 0 && tpl[0] != '/' {
 			return fmt.Errorf("mux: path must start with a slash, got %q", tpl)
 		}
@@ -162,7 +186,10 @@ func (r *Route) addRegexpMatcher(tpl string, matchHost, matchPrefix, matchQuery
 			tpl = strings.TrimRight(r.regexp.path.template, "/") + tpl
 		}
 	}
-	rr, err := newRouteRegexp(tpl, matchHost, matchPrefix, matchQuery, r.strictSlash, r.useEncodedPath)
+	rr, err := newRouteRegexp(tpl, typ, routeRegexpOptions{
+		strictSlash:    r.strictSlash,
+		useEncodedPath: r.useEncodedPath,
+	})
 	if err != nil {
 		return err
 	}
@@ -171,7 +198,7 @@ func (r *Route) addRegexpMatcher(tpl string, matchHost, matchPrefix, matchQuery
 			return err
 		}
 	}
-	if matchHost {
+	if typ == regexpTypeHost {
 		if r.regexp.path != nil {
 			if err = uniqueVars(rr.varsN, r.regexp.path.varsN); err != nil {
 				return err
@@ -184,7 +211,7 @@ func (r *Route) addRegexpMatcher(tpl string, matchHost, matchPrefix, matchQuery
 				return err
 			}
 		}
-		if matchQuery {
+		if typ == regexpTypeQuery {
 			r.regexp.queries = append(r.regexp.queries, rr)
 		} else {
 			r.regexp.path = rr
@@ -236,7 +263,8 @@ func (m headerRegexMatcher) Match(r *http.Request, match *RouteMatch) bool {
 //               "X-Requested-With", "XMLHttpRequest")
 //
 // The above route will only match if both the request header matches both regular expressions.
-// It the value is an empty string, it will match any value if the key is set.
+// If the value is an empty string, it will match any value if the key is set.
+// Use the start and end of string anchors (^ and $) to match an exact value.
 func (r *Route) HeadersRegexp(pairs ...string) *Route {
 	if r.err == nil {
 		var headers map[string]*regexp.Regexp
@@ -266,7 +294,7 @@ func (r *Route) HeadersRegexp(pairs ...string) *Route {
 // Variable names must be unique in a given route. They can be retrieved
 // calling mux.Vars(request).
 func (r *Route) Host(tpl string) *Route {
-	r.err = r.addRegexpMatcher(tpl, true, false, false)
+	r.err = r.addRegexpMatcher(tpl, regexpTypeHost)
 	return r
 }
 
@@ -326,7 +354,7 @@ func (r *Route) Methods(methods ...string) *Route {
 // Variable names must be unique in a given route. They can be retrieved
 // calling mux.Vars(request).
 func (r *Route) Path(tpl string) *Route {
-	r.err = r.addRegexpMatcher(tpl, false, false, false)
+	r.err = r.addRegexpMatcher(tpl, regexpTypePath)
 	return r
 }
 
@@ -342,7 +370,7 @@ func (r *Route) Path(tpl string) *Route {
 // Also note that the setting of Router.StrictSlash() has no effect on routes
 // with a PathPrefix matcher.
 func (r *Route) PathPrefix(tpl string) *Route {
-	r.err = r.addRegexpMatcher(tpl, false, true, false)
+	r.err = r.addRegexpMatcher(tpl, regexpTypePrefix)
 	return r
 }
 
@@ -373,7 +401,7 @@ func (r *Route) Queries(pairs ...string) *Route {
 		return nil
 	}
 	for i := 0; i < length; i += 2 {
-		if r.err = r.addRegexpMatcher(pairs[i]+"="+pairs[i+1], false, false, true); r.err != nil {
+		if r.err = r.addRegexpMatcher(pairs[i]+"="+pairs[i+1], regexpTypeQuery); r.err != nil {
 			return r
 		}
 	}
@@ -482,13 +510,14 @@ func (r *Route) URL(pairs ...string) (*url.URL, error) {
 		return nil, err
 	}
 	var scheme, host, path string
+	queries := make([]string, 0, len(r.regexp.queries))
 	if r.regexp.host != nil {
 		if host, err = r.regexp.host.url(values); err != nil {
 			return nil, err
 		}
 		scheme = "http"
-		if r.buildScheme != "" {
-			scheme = r.buildScheme
+		if s := r.getBuildScheme(); s != "" {
+			scheme = s
 		}
 	}
 	if r.regexp.path != nil {
@@ -496,10 +525,18 @@ func (r *Route) URL(pairs ...string) (*url.URL, error) {
 			return nil, err
 		}
 	}
+	for _, q := range r.regexp.queries {
+		var query string
+		if query, err = q.url(values); err != nil {
+			return nil, err
+		}
+		queries = append(queries, query)
+	}
 	return &url.URL{
-		Scheme: scheme,
-		Host:   host,
-		Path:   path,
+		Scheme:   scheme,
+		Host:     host,
+		Path:     path,
+		RawQuery: strings.Join(queries, "&"),
 	}, nil
 }
 
@@ -525,8 +562,8 @@ func (r *Route) URLHost(pairs ...string) (*url.URL, error) {
 		Scheme: "http",
 		Host:   host,
 	}
-	if r.buildScheme != "" {
-		u.Scheme = r.buildScheme
+	if s := r.getBuildScheme(); s != "" {
+		u.Scheme = s
 	}
 	return u, nil
 }
@@ -583,10 +620,48 @@ func (r *Route) GetPathRegexp() (string, error) {
 	return r.regexp.path.regexp.String(), nil
 }
 
+// GetQueriesRegexp returns the expanded regular expressions used to match the
+// route queries.
+// This is useful for building simple REST API documentation and for instrumentation
+// against third-party services.
+// An error will be returned if the route does not have queries.
+func (r *Route) GetQueriesRegexp() ([]string, error) {
+	if r.err != nil {
+		return nil, r.err
+	}
+	if r.regexp == nil || r.regexp.queries == nil {
+		return nil, errors.New("mux: route doesn't have queries")
+	}
+	var queries []string
+	for _, query := range r.regexp.queries {
+		queries = append(queries, query.regexp.String())
+	}
+	return queries, nil
+}
+
+// GetQueriesTemplates returns the templates used to build the
+// query matching.
+// This is useful for building simple REST API documentation and for instrumentation
+// against third-party services.
+// An error will be returned if the route does not define queries.
+func (r *Route) GetQueriesTemplates() ([]string, error) {
+	if r.err != nil {
+		return nil, r.err
+	}
+	if r.regexp == nil || r.regexp.queries == nil {
+		return nil, errors.New("mux: route doesn't have queries")
+	}
+	var queries []string
+	for _, query := range r.regexp.queries {
+		queries = append(queries, query.template)
+	}
+	return queries, nil
+}
+
 // GetMethods returns the methods the route matches against
 // This is useful for building simple REST API documentation and for instrumentation
 // against third-party services.
-// An empty list will be returned if route does not have methods.
+// An error will be returned if route does not have methods.
 func (r *Route) GetMethods() ([]string, error) {
 	if r.err != nil {
 		return nil, r.err
@@ -596,7 +671,7 @@ func (r *Route) GetMethods() ([]string, error) {
 			return []string(methods), nil
 		}
 	}
-	return nil, nil
+	return nil, errors.New("mux: route doesn't have methods")
 }
 
 // GetHostTemplate returns the template used to build the
@@ -640,11 +715,22 @@ func (r *Route) buildVars(m map[string]string) map[string]string {
 
 // parentRoute allows routes to know about parent host and path definitions.
 type parentRoute interface {
+	getBuildScheme() string
 	getNamedRoutes() map[string]*Route
 	getRegexpGroup() *routeRegexpGroup
 	buildVars(map[string]string) map[string]string
 }
 
+func (r *Route) getBuildScheme() string {
+	if r.buildScheme != "" {
+		return r.buildScheme
+	}
+	if r.parent != nil {
+		return r.parent.getBuildScheme()
+	}
+	return ""
+}
+
 // getNamedRoutes returns the map where named routes are registered.
 func (r *Route) getNamedRoutes() map[string]*Route {
 	if r.parent == nil {

test_helpers.go

@@ -0,0 +1,19 @@
+// 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 "net/http"
+
+// SetURLVars sets the URL variables for the given request, to be accessed via
+// mux.Vars for testing route behaviour. Arguments are not modified, a shallow
+// copy is returned.
+//
+// This API should only be used for testing purposes; it provides a way to
+// inject variables into the request context. Alternatively, URL variables
+// can be set by making a route that captures the required variables,
+// starting a server and sending the request to that server.
+func SetURLVars(r *http.Request, val map[string]string) *http.Request {
+	return setVars(r, val)
+}