handle.go
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handle.go
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	/*
	* Copyright © 2018 A Bunch Tell LLC.
	*
	* This file is part of WriteFreely.
	*
	* WriteFreely is free software: you can redistribute it and/or modify
	* it under the terms of the GNU Affero General Public License, included
	* in the LICENSE file in this source code package.
	*/

	package writefreely

	import (
	"fmt"
	"html/template"
	"net/http"
	"net/url"
	"runtime/debug"
	"strconv"
	"strings"
	"time"

	"github.com/gorilla/sessions"
	"github.com/writeas/impart"
	"github.com/writeas/web-core/log"
	"github.com/writeas/writefreely/page"
	)

	type UserLevel int

	const (
	UserLevelNone UserLevel = iota // user or not -- ignored
	UserLevelOptional // user or not -- object fetched if user
	UserLevelNoneRequired // non-user (required)
	UserLevelUser // user (required)
	)

	type (
	handlerFunc func(app App, w http.ResponseWriter, r http.Request) error
	userHandlerFunc func(app App, u User, w http.ResponseWriter, r *http.Request) error
	dataHandlerFunc func(app App, w http.ResponseWriter, r http.Request) ([]byte, string, error)
	authFunc func(app App, r http.Request) (*User, error)
	)

	type Handler struct {
	errors *ErrorPages
	sessionStore *sessions.CookieStore
	app *App
	}

	// ErrorPages hold template HTML error pages for displaying errors to the user.
	// In each, there should be a defined template named "base".
	type ErrorPages struct {
	NotFound *template.Template
	Gone *template.Template
	InternalServerError *template.Template
	Blank *template.Template
	}

	// NewHandler returns a new Handler instance, using the given StaticPage data,
	// and saving alias to the application's CookieStore.
	func NewHandler(app App) Handler {
	h := &Handler{
	errors: &ErrorPages{
	NotFound: template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>404</title></head><body><p>Not found.</p></body></html>{{end}}")),
	Gone: template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>410</title></head><body><p>Gone.</p></body></html>{{end}}")),
	InternalServerError: template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>500</title></head><body><p>Internal server error.</p></body></html>{{end}}")),
	Blank: template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>{{.Title}}</title></head><body><p>{{.Content}}</p></body></html>{{end}}")),
	},
	sessionStore: app.sessionStore,
	app: app,
	}

	return h
	}

	// NewWFHandler returns a new Handler instance, using WriteFreely template files.
	// You MUST call writefreely.InitTemplates() before this.
	func NewWFHandler(app App) Handler {
	h := NewHandler(app)
	h.SetErrorPages(&ErrorPages{
	NotFound: pages["404-general.tmpl"],
	Gone: pages["410.tmpl"],
	InternalServerError: pages["500.tmpl"],
	Blank: pages["blank.tmpl"],
	})
	return h
	}

	// SetErrorPages sets the given set of ErrorPages as templates for any errors
	// that come up.
	func (h Handler) SetErrorPages(e ErrorPages) {
	h.errors = e
	}

	// User handles requests made in the web application by the authenticated user.
	// This provides user-friendly HTML pages and actions that work in the browser.
	func (h *Handler) User(f userHandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	h.handleHTTPError(w, r, func() error {
	var status int
	start := time.Now()

	defer func() {
	if e := recover(); e != nil {
	log.Error("%s: %s", e, debug.Stack())
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	status = http.StatusInternalServerError
	}

	log.Info("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent())
	}()

	u := getUserSession(h.app, r)
	if u == nil {
	err := ErrNotLoggedIn
	status = err.Status
	return err
	}

	err := f(h.app, u, w, r)
	if err == nil {
	status = http.StatusOK
	} else if err, ok := err.(impart.HTTPError); ok {
	status = err.Status
	} else {
	status = http.StatusInternalServerError
	}

	return err
	}())
	}
	}

	// Admin handles requests on /admin routes
	func (h *Handler) Admin(f userHandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	h.handleHTTPError(w, r, func() error {
	var status int
	start := time.Now()

	defer func() {
	if e := recover(); e != nil {
	log.Error("%s: %s", e, debug.Stack())
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	status = http.StatusInternalServerError
	}

	log.Info(fmt.Sprintf("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent()))
	}()

	u := getUserSession(h.app, r)
	if u == nil \|\| !u.IsAdmin() {
	err := impart.HTTPError{http.StatusNotFound, ""}
	status = err.Status
	return err
	}

	err := f(h.app, u, w, r)
	if err == nil {
	status = http.StatusOK
	} else if err, ok := err.(impart.HTTPError); ok {
	status = err.Status
	} else {
	status = http.StatusInternalServerError
	}

	return err
	}())
	}
	}

	// UserAPI handles requests made in the API by the authenticated user.
	// This provides user-friendly HTML pages and actions that work in the browser.
	func (h *Handler) UserAPI(f userHandlerFunc) http.HandlerFunc {
	return h.UserAll(false, f, func(app App, r http.Request) (*User, error) {
	// Authorize user from Authorization header
	t := r.Header.Get("Authorization")
	if t == "" {
	return nil, ErrNoAccessToken
	}
	u := &User{ID: app.db.GetUserID(t)}
	if u.ID == -1 {
	return nil, ErrBadAccessToken
	}

	return u, nil
	})
	}

	func (h *Handler) UserAll(web bool, f userHandlerFunc, a authFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	handleFunc := func() error {
	var status int
	start := time.Now()

	defer func() {
	if e := recover(); e != nil {
	log.Error("%s: %s", e, debug.Stack())
	impart.WriteError(w, impart.HTTPError{http.StatusInternalServerError, "Something didn't work quite right."})
	status = 500
	}

	log.Info("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent())
	}()

	u, err := a(h.app, r)
	if err != nil {
	if err, ok := err.(impart.HTTPError); ok {
	status = err.Status
	} else {
	status = 500
	}
	return err
	}

	err = f(h.app, u, w, r)
	if err == nil {
	status = 200
	} else if err, ok := err.(impart.HTTPError); ok {
	status = err.Status
	} else {
	status = 500
	}

	return err
	}

	if web {
	h.handleHTTPError(w, r, handleFunc())
	} else {
	h.handleError(w, r, handleFunc())
	}
	}
	}

	func (h *Handler) RedirectOnErr(f handlerFunc, loc string) handlerFunc {
	return func(app App, w http.ResponseWriter, r http.Request) error {
	err := f(app, w, r)
	if err != nil {
	if ie, ok := err.(impart.HTTPError); ok {
	// Override default redirect with returned error's, if it's a
	// redirect error.
	if ie.Status == http.StatusFound {
	return ie
	}
	}
	return impart.HTTPError{http.StatusFound, loc}
	}
	return nil
	}
	}

	func (h *Handler) Page(n string) http.HandlerFunc {
	return h.Web(func(app App, w http.ResponseWriter, r http.Request) error {
	t, ok := pages[n]
	if !ok {
	return impart.HTTPError{http.StatusNotFound, "Page not found."}
	}

	sp := pageForReq(app, r)

	err := t.ExecuteTemplate(w, "base", sp)
	if err != nil {
	log.Error("Unable to render page: %v", err)
	}
	return err
	}, UserLevelOptional)
	}

	func (h *Handler) WebErrors(f handlerFunc, ul UserLevel) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	// TODO: factor out this logic shared with Web()
	h.handleHTTPError(w, r, func() error {
	var status int
	start := time.Now()

	defer func() {
	if e := recover(); e != nil {
	u := getUserSession(h.app, r)
	username := "None"
	if u != nil {
	username = u.Username
	}
	log.Error("User: %s\n\n%s: %s", username, e, debug.Stack())
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	status = 500
	}

	log.Info("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent())
	}()

	var session *sessions.Session
	var err error
	if ul != UserLevelNone {
	session, err = h.sessionStore.Get(r, cookieName)
	if err != nil && (ul == UserLevelNoneRequired \|\| ul == UserLevelUser) {
	// Cookie is required, but we can ignore this error
	log.Error("Handler: Unable to get session (for user permission %d); ignoring: %v", ul, err)
	}

	_, gotUser := session.Values[cookieUserVal].(*User)
	if ul == UserLevelNoneRequired && gotUser {
	to := correctPageFromLoginAttempt(r)
	log.Info("Handler: Required NO user, but got one. Redirecting to %s", to)
	err := impart.HTTPError{http.StatusFound, to}
	status = err.Status
	return err
	} else if ul == UserLevelUser && !gotUser {
	log.Info("Handler: Required a user, but DIDN'T get one. Sending not logged in.")
	err := ErrNotLoggedIn
	status = err.Status
	return err
	}
	}

	// TODO: pass User object to function
	err = f(h.app, w, r)
	if err == nil {
	status = 200
	} else if httpErr, ok := err.(impart.HTTPError); ok {
	status = httpErr.Status
	if status < 300 \|\| status > 399 {
	addSessionFlash(h.app, w, r, httpErr.Message, session)
	return impart.HTTPError{http.StatusFound, r.Referer()}
	}
	} else {
	e := fmt.Sprintf("[Web handler] 500: %v", err)
	if !strings.HasSuffix(e, "write: broken pipe") {
	log.Error(e)
	} else {
	log.Error(e)
	}
	log.Info("Web handler internal error render")
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	status = 500
	}

	return err
	}())
	}
	}

	// Web handles requests made in the web application. This provides user-
	// friendly HTML pages and actions that work in the browser.
	func (h *Handler) Web(f handlerFunc, ul UserLevel) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	h.handleHTTPError(w, r, func() error {
	var status int
	start := time.Now()

	defer func() {
	if e := recover(); e != nil {
	u := getUserSession(h.app, r)
	username := "None"
	if u != nil {
	username = u.Username
	}
	log.Error("User: %s\n\n%s: %s", username, e, debug.Stack())
	log.Info("Web deferred internal error render")
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	status = 500
	}

	log.Info("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent())
	}()

	if ul != UserLevelNone {
	session, err := h.sessionStore.Get(r, cookieName)
	if err != nil && (ul == UserLevelNoneRequired \|\| ul == UserLevelUser) {
	// Cookie is required, but we can ignore this error
	log.Error("Handler: Unable to get session (for user permission %d); ignoring: %v", ul, err)
	}

	_, gotUser := session.Values[cookieUserVal].(*User)
	if ul == UserLevelNoneRequired && gotUser {
	to := correctPageFromLoginAttempt(r)
	log.Info("Handler: Required NO user, but got one. Redirecting to %s", to)
	err := impart.HTTPError{http.StatusFound, to}
	status = err.Status
	return err
	} else if ul == UserLevelUser && !gotUser {
	log.Info("Handler: Required a user, but DIDN'T get one. Sending not logged in.")
	err := ErrNotLoggedIn
	status = err.Status
	return err
	}
	}

	// TODO: pass User object to function
	err := f(h.app, w, r)
	if err == nil {
	status = 200
	} else if httpErr, ok := err.(impart.HTTPError); ok {
	status = httpErr.Status
	} else {
	e := fmt.Sprintf("[Web handler] 500: %v", err)
	log.Error(e)
	log.Info("Web internal error render")
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	status = 500
	}

	return err
	}())
	}
	}

	func (h *Handler) All(f handlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	h.handleError(w, r, func() error {
	// TODO: return correct "success" status
	status := 200
	start := time.Now()

	defer func() {
	if e := recover(); e != nil {
	log.Error("%s:\n%s", e, debug.Stack())
	impart.WriteError(w, impart.HTTPError{http.StatusInternalServerError, "Something didn't work quite right."})
	status = 500
	}

	log.Info("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent())
	}()

	// TODO: do any needed authentication

	err := f(h.app, w, r)
	if err != nil {
	if err, ok := err.(impart.HTTPError); ok {
	status = err.Status
	} else {
	status = 500
	}
	}

	return err
	}())
	}
	}

	func (h *Handler) Download(f dataHandlerFunc, ul UserLevel) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	h.handleHTTPError(w, r, func() error {
	var status int
	start := time.Now()
	defer func() {
	if e := recover(); e != nil {
	log.Error("%s: %s", e, debug.Stack())
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	status = 500
	}

	log.Info("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent())
	}()

	data, filename, err := f(h.app, w, r)
	if err != nil {
	if err, ok := err.(impart.HTTPError); ok {
	status = err.Status
	} else {
	status = 500
	}
	return err
	}

	ext := ".json"
	ct := "application/json"
	if strings.HasSuffix(r.URL.Path, ".csv") {
	ext = ".csv"
	ct = "text/csv"
	} else if strings.HasSuffix(r.URL.Path, ".zip") {
	ext = ".zip"
	ct = "application/zip"
	}
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%s%s", filename, ext))
	w.Header().Set("Content-Type", ct)
	w.Header().Set("Content-Length", strconv.Itoa(len(data)))
	fmt.Fprint(w, string(data))

	status = 200
	return nil
	}())
	}
	}

	func (h *Handler) Redirect(url string, ul UserLevel) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	h.handleHTTPError(w, r, func() error {
	start := time.Now()

	var status int
	if ul != UserLevelNone {
	session, err := h.sessionStore.Get(r, cookieName)
	if err != nil && (ul == UserLevelNoneRequired \|\| ul == UserLevelUser) {
	// Cookie is required, but we can ignore this error
	log.Error("Handler: Unable to get session (for user permission %d); ignoring: %v", ul, err)
	}

	_, gotUser := session.Values[cookieUserVal].(*User)
	if ul == UserLevelNoneRequired && gotUser {
	to := correctPageFromLoginAttempt(r)
	log.Info("Handler: Required NO user, but got one. Redirecting to %s", to)
	err := impart.HTTPError{http.StatusFound, to}
	status = err.Status
	return err
	} else if ul == UserLevelUser && !gotUser {
	log.Info("Handler: Required a user, but DIDN'T get one. Sending not logged in.")
	err := ErrNotLoggedIn
	status = err.Status
	return err
	}
	}

	status = sendRedirect(w, http.StatusFound, url)

	log.Info("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent())

	return nil
	}())
	}
	}

	func (h Handler) handleHTTPError(w http.ResponseWriter, r http.Request, err error) {
	if err == nil {
	return
	}

	if err, ok := err.(impart.HTTPError); ok {
	if err.Status >= 300 && err.Status < 400 {
	sendRedirect(w, err.Status, err.Message)
	return
	} else if err.Status == http.StatusUnauthorized {
	q := ""
	if r.URL.RawQuery != "" {
	q = url.QueryEscape("?" + r.URL.RawQuery)
	}
	sendRedirect(w, http.StatusFound, "/login?to="+r.URL.Path+q)
	return
	} else if err.Status == http.StatusGone {
	w.WriteHeader(err.Status)
	p := &struct {
	page.StaticPage
	Content *template.HTML
	}{
	StaticPage: pageForReq(h.app, r),
	}
	if err.Message != "" {
	co := template.HTML(err.Message)
	p.Content = &co
	}
	h.errors.Gone.ExecuteTemplate(w, "base", p)
	return
	} else if err.Status == http.StatusNotFound {
	w.WriteHeader(err.Status)
	h.errors.NotFound.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	return
	} else if err.Status == http.StatusInternalServerError {
	w.WriteHeader(err.Status)
	log.Info("handleHTTPErorr internal error render")
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	return
	} else if err.Status == http.StatusAccepted {
	impart.WriteSuccess(w, "", err.Status)
	return
	} else {
	p := &struct {
	page.StaticPage
	Title string
	Content template.HTML
	}{
	pageForReq(h.app, r),
	fmt.Sprintf("Uh oh (%d)", err.Status),
	template.HTML(fmt.Sprintf("<p style=\"text-align: center\" class=\"introduction\">%s</p>", err.Message)),
	}
	h.errors.Blank.ExecuteTemplate(w, "base", p)
	return
	}
	impart.WriteError(w, err)
	return
	}

	impart.WriteError(w, impart.HTTPError{http.StatusInternalServerError, "This is an unhelpful error message for a miscellaneous internal error."})
	}

	func (h Handler) handleError(w http.ResponseWriter, r http.Request, err error) {
	if err == nil {
	return
	}

	if err, ok := err.(impart.HTTPError); ok {
	if err.Status >= 300 && err.Status < 400 {
	sendRedirect(w, err.Status, err.Message)
	return
	}

	// if strings.Contains(r.Header.Get("Accept"), "text/html") {
	impart.WriteError(w, err)
	// }
	return
	}

	if IsJSON(r.Header.Get("Content-Type")) {
	impart.WriteError(w, impart.HTTPError{http.StatusInternalServerError, "This is an unhelpful error message for a miscellaneous internal error."})
	return
	}
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	}

	func correctPageFromLoginAttempt(r *http.Request) string {
	to := r.FormValue("to")
	if to == "" {
	to = "/"
	} else if !strings.HasPrefix(to, "/") {
	to = "/" + to
	}
	return to
	}

	func (h *Handler) LogHandlerFunc(f http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	h.handleHTTPError(w, r, func() error {
	status := 200
	start := time.Now()

	defer func() {
	if e := recover(); e != nil {
	log.Error("Handler.LogHandlerFunc\n\n%s: %s", e, debug.Stack())
	h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app, r))
	status = 500
	}

	// TODO: log actual status code returned
	log.Info("\"%s %s\" %d %s \"%s\"", r.Method, r.RequestURI, status, time.Since(start), r.UserAgent())
	}()

	f(w, r)

	return nil
	}())
	}
	}

	func sendRedirect(w http.ResponseWriter, code int, location string) int {
	w.Header().Set("Location", location)
	w.WriteHeader(code)
	return code
	}

File Metadata

Mime Type: text/html
Expires: Sat, Nov 23, 7:43 AM (1 d, 13 h)
Storage Engine: blob
Storage Format: Raw Data
Storage Handle: 3104450

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