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routes.go
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routes.go
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package routes
import (
"encoding/json"
"encoding/xml"
"io/ioutil"
"log"
"net/http"
"net/url"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"time"
)
const (
CONNECT = "CONNECT"
DELETE = "DELETE"
GET = "GET"
HEAD = "HEAD"
OPTIONS = "OPTIONS"
PATCH = "PATCH"
POST = "POST"
PUT = "PUT"
TRACE = "TRACE"
// log format, modeled after http://wiki.nginx.org/HttpLogModule
LOG = `%s - - [%s] "%s %s %s" %d %d "%s" "%s"`
// commonly used mime types
applicationJson = "application/json"
applicationXml = "application/xml"
textXml = "text/xml"
)
type Route struct {
method string
regex *regexp.Regexp
params map[int]string
handler http.HandlerFunc
auth AuthHandler
}
type RouteMux struct {
routes []*Route
static bool
static_dir string
Logging bool
Logger *log.Logger
}
func New() *RouteMux {
routeMux := RouteMux{}
routeMux.static = false
routeMux.static_dir = ""
routeMux.Logging = true
routeMux.Logger = log.New(os.Stdout, "", 0)
return &routeMux
}
// Adds a new Route to the Handler
func (this *RouteMux) AddRoute(method string, pattern string, handler http.HandlerFunc) *Route {
//split the url into sections
parts := strings.Split(pattern, "/")
//find params that start with ":"
//replace with regular expressions
j := 0
params := make(map[int]string)
for i, part := range parts {
if strings.HasPrefix(part, ":") {
expr := "([^/]+)"
//a user may choose to override the defult expression
// similar to expressjs: ‘/user/:id([0-9]+)’
if index := strings.Index(part, "("); index != -1 {
expr = part[index:]
part = part[:index]
}
params[j] = part
parts[i] = expr
j++
}
}
//recreate the url pattern, with parameters replaced
//by regular expressions. then compile the regex
pattern = strings.Join(parts, "/")
regex, regexErr := regexp.Compile(pattern)
if regexErr != nil {
//TODO add error handling here to avoid panic
panic(regexErr)
return nil
}
//now create the Route
route := &Route{}
route.method = method
route.regex = regex
route.handler = handler
route.params = params
//and finally append to the list of Routes
this.routes = append(this.routes, route)
return route
}
// Adds a new Route for GET requests
func (this *RouteMux) Get(pattern string, handler http.HandlerFunc) *Route {
return this.AddRoute(GET, pattern, handler)
}
// Adds a new Route for PUT requests
func (this *RouteMux) Put(pattern string, handler http.HandlerFunc) *Route {
return this.AddRoute(PUT, pattern, handler)
}
// Adds a new Route for DELETE requests
func (this *RouteMux) Del(pattern string, handler http.HandlerFunc) *Route {
return this.AddRoute(DELETE, pattern, handler)
}
// Adds a new Route for PATCH requests
// See http://www.ietf.org/rfc/rfc5789.txt
func (this *RouteMux) Patch(pattern string, handler http.HandlerFunc) *Route {
return this.AddRoute(PATCH, pattern, handler)
}
// Adds a new Route for POST requests
func (this *RouteMux) Post(pattern string, handler http.HandlerFunc) *Route {
return this.AddRoute(POST, pattern, handler)
}
// Secures a route using the default AuthHandler
func (this *Route) Secure() *Route {
this.auth = DefaultAuthHandler
return this
}
// SecureFunc a route using a custom AuthHandler function
func (this *Route) SecureFunc(handler AuthHandler) *Route {
this.auth = handler
return this
}
// Adds a new Route for Static http requests. Serves
// static files from the specified directory
func (this *RouteMux) Static(pattern string, dir string) *Route {
//append a regex to the param to match everything
// that comes after the prefix
pattern = pattern + "(.+)"
return this.AddRoute(GET, pattern, func(w http.ResponseWriter, r *http.Request) {
path := filepath.Clean(r.URL.Path)
path = filepath.Join(dir, path)
http.ServeFile(w, r, path)
})
}
// Adds a default static path for paths which do not match any routes
func (this *RouteMux) DefaultStatic(dir string) {
this.static = true
this.static_dir = dir
}
// Required by http.Handler interface. This method is invoked by the
// http server and will handle all page routing
func (this *RouteMux) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
requestPath := r.URL.Path
//wrap the response writer, in our custom interface
w := &responseWriter{writer: rw}
//find a matching Route
for _, route := range this.routes {
//if the methods don't match, skip this handler
//i.e if request.Method is 'PUT' Route.Method must be 'PUT'
if r.Method != route.method {
continue
}
//check if Route pattern matches url
if !route.regex.MatchString(requestPath) {
continue
}
//get submatches (params)
matches := route.regex.FindStringSubmatch(requestPath)
//double check that the Route matches the URL pattern.
if len(matches[0]) != len(requestPath) {
continue
}
//add url parameters to the query param map
values := r.URL.Query()
for i, match := range matches[1:] {
values.Add(route.params[i], match)
}
//reassemble query params and add to RawQuery
r.URL.RawQuery = url.Values(values).Encode()
//enfore security, if necessary
if route.auth != nil {
//autenticate the user
ok := route.auth(w, r)
//if the auth handler redirected the user
//or already wrote a response, we can just exit
if w.started {
return
} else if ok == false {
http.Error(w, "Unauthorized", http.StatusUnauthorized)
}
}
//Invoke the request handler
route.handler(w, r)
// if the response has been written, break
if w.started {
break
} else {
// remove the values written to the url
values := r.URL.Query()
for i, _ := range matches[1:] {
values.Del(route.params[i])
}
//reassemble query params and add to RawQuery
r.URL.RawQuery = url.Values(values).Encode()
}
}
//if no matches to url
if w.started == false {
// if a static route is set, attempt to send the file, else return 404
if this.static {
path := filepath.Clean(r.URL.Path)
path = filepath.Join(this.static_dir, path)
http.ServeFile(w, r, path)
} else {
http.NotFound(w, r)
}
}
//if logging is turned on
if this.Logging {
this.Logger.Printf(LOG, r.RemoteAddr, time.Now().String(), r.Method,
r.URL.Path, r.Proto, w.status, w.size,
r.Referer(), r.UserAgent())
}
}
// ---------------------------------------------------------------------------------
// Simple wrapper around a ResponseWriter
//responseWriter is a wrapper for the http.ResponseWriter
// to track if response was written to. It also allows us
// to automatically set certain headers, such as Content-Type,
// Access-Control-Allow-Origin, etc.
type responseWriter struct {
writer http.ResponseWriter // Writer
started bool
size int
status int
}
// Header returns the header map that will be sent by WriteHeader.
func (this *responseWriter) Header() http.Header {
return this.writer.Header()
}
// Write writes the data to the connection as part of an HTTP reply,
// and sets `started` to true
func (this *responseWriter) Write(p []byte) (int, error) {
this.size += len(p)
this.started = true
return this.writer.Write(p)
}
// WriteHeader sends an HTTP response header with status code,
// and sets `started` to true
func (this *responseWriter) WriteHeader(code int) {
this.status = code
this.started = true
this.writer.WriteHeader(code)
}
// ---------------------------------------------------------------------------------
// Authentication helper functions to enable user authentication
type AuthHandler func(http.ResponseWriter, *http.Request) bool
// DefaultAuthHandler will be applied to any route when the Secure() function
// is invoked, as opposed to SecureFunc(), which accepts a custom AuthHandler.
//
// By default, the DefaultAuthHandler will deny all requests. This value
// should be replaced with a custom AuthHandler implementation, as this
// is just a dummy function.
var DefaultAuthHandler = func(w http.ResponseWriter, r *http.Request) bool {
return false
}
// ---------------------------------------------------------------------------------
// Below are helper functions to replace boilerplate
// code that serializes resources and writes to the
// http response.
// ServeJson replies to the request with a JSON
// representation of resource v.
func ServeJson(w http.ResponseWriter, v interface{}) {
content, err := json.MarshalIndent(v, "", " ")
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.Write(content)
w.Header().Set("Content-Length", strconv.Itoa(len(content)))
w.Header().Set("Content-Type", applicationJson)
}
// ReadJson will parses the JSON-encoded data in the http
// Request object and stores the result in the value
// pointed to by v.
func ReadJson(r *http.Request, v interface{}) error {
body, err := ioutil.ReadAll(r.Body)
r.Body.Close()
if err != nil {
return err
}
return json.Unmarshal(body, v)
}
// ServeXml replies to the request with an XML
// representation of resource v.
func ServeXml(w http.ResponseWriter, v interface{}) {
content, err := xml.Marshal(v)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.Write(content)
w.Header().Set("Content-Length", strconv.Itoa(len(content)))
w.Header().Set("Content-Type", "text/xml; charset=utf-8")
}
// ReadXml will parses the XML-encoded data in the http
// Request object and stores the result in the value
// pointed to by v.
func ReadXml(r *http.Request, v interface{}) error {
body, err := ioutil.ReadAll(r.Body)
r.Body.Close()
if err != nil {
return err
}
return xml.Unmarshal(body, v)
}
// ServeFormatted replies to the request with
// a formatted representation of resource v, in the
// format requested by the client specified in the
// Accept header.
func ServeFormatted(w http.ResponseWriter, r *http.Request, v interface{}) {
accept := r.Header.Get("Accept")
switch accept {
case applicationJson:
ServeJson(w, v)
case applicationXml, textXml:
ServeXml(w, v)
default:
ServeJson(w, v)
}
return
}