webhooker/internal/server/routes.go

package server

import (
	"net/http"
	"time"

	sentryhttp "github.com/getsentry/sentry-go/http"
	"github.com/go-chi/chi"
	"github.com/go-chi/chi/middleware"
	"sneak.berlin/go/webhooker/static"
)

// maxFormBodySize is the maximum allowed request body size (in
// bytes) for form POST endpoints. 1 MB is generous for any form
// submission while preventing abuse from oversized payloads.
//
// The four admin page route groups below (/pages, /user/{username},
// /hooks and /hook/{sourceID}) install MaxBodySize(maxFormBodySize)
// right after their recoverer and error reporting, ahead of both CSRF
// and RequireAuth. Both orderings are deliberate.
//
// Ahead of CSRF because gorilla/csrf parses the form. The cap has to
// be installed before anything reads the body, or the parse runs
// under net/http's 10 MB default instead of this one.
//
// Ahead of RequireAuth because an oversize body should be refused
// before the request buys a cookie decrypt, a session load and the
// database read behind it. Rejecting first is the cheaper failure,
// and it is the ordering that keeps an unauthenticated flood from
// choosing how much session work the process does.
//
// What that ordering costs: the 413 branch is reachable
// unauthenticated, at a URL of the client's choosing and of the
// client's chosen length. So is the CSRF rejection, which sits in
// front of RequireAuth for the same reason. Both log that path, so
// both cap it — see the log calls in Middleware.MaxBodySize and
// Middleware.CSRF, which spend the same per-field budget as the
// access log.
const maxFormBodySize int64 = 1 * 1024 * 1024 // 1 MB

// requestTimeout is the maximum time allowed for a single HTTP
// request.
const requestTimeout = 60 * time.Second

// SetupRoutes configures all HTTP routes and middleware on the
// server's router.
func (s *Server) SetupRoutes() {
	s.router = chi.NewRouter()

	// An unknown path gets the error page. Registered before the
	// global middleware, because chi wraps a not-found handler in the
	// middleware already on its router, which would then run twice.
	// The route groups below wrap it in their own middleware the same
	// way; running theirs twice is harmless.
	s.router.NotFound(s.h.HandleErrorPage(http.StatusNotFound))

	s.setupGlobalMiddleware()
	s.setupRoutes()
}

func (s *Server) setupGlobalMiddleware() {
	s.router.Use(middleware.RequestID)
	s.router.Use(s.mw.SecurityHeaders())

	// Metrics recording middleware, registered only when the
	// endpoint that exposes what it records is served. The
	// condition is the same MetricsAuthEnabled the /metrics mount
	// in setupRoutes reads.
	//
	// It goes outside Logging. go-http-metrics' writer passes a flush
	// on only when the writer inside it has a Flush method, and the
	// access log's writer has none, so inside Logging a handler's
	// flush would silently do nothing.
	if s.params.Config.MetricsAuthEnabled() {
		s.router.Use(s.mw.Metrics())
	}

	s.router.Use(s.mw.Logging())
	s.router.Use(s.mw.CORS())
	s.router.Use(middleware.Timeout(requestTimeout))

	// Panic recovery, deliberately here rather than first. It has to
	// run inside every middleware that observes the response, so the
	// 500 it writes is the status the access log records and the
	// metrics count, and outside the sentryhttp handler, whose
	// Repanic option needs something further out to catch what it
	// re-raises. chi's own middleware.Recoverer held the first slot
	// until it was measured: on a current Go release it crashes
	// inside its stack pretty-printer instead of recovering, so the
	// connection dropped and the original panic was never reported.
	// See https://git.eeqj.de/sneak/webhooker/issues/187.
	s.recoverPanics(s.router, nil)
}

// recoverPanics installs on r the recoverer, answering a panic with
// page (a plain 500 when page is nil), and inside it the Sentry error
// reporting (if SENTRY_DSN is set). Repanic is true so panics still
// bubble up to the recoverer.
//
// Each admin page route group installs its own, with the error page,
// as its first middleware. A panic there is logged, reported and
// answered inside the group and never reaches the global recoverer,
// which keeps the plain 500 for every other route.
func (s *Server) recoverPanics(r chi.Router, page http.Handler) {
	r.Use(s.mw.Recoverer(page))

	if s.sentryEnabled.Load() {
		sentryHandler := sentryhttp.New(sentryhttp.Options{
			Repanic: true,
		})
		r.Use(sentryHandler.Handle)
	}
}

func (s *Server) setupRoutes() {
	s.router.Get("/", s.h.HandleIndex())

	// Static assets answer GET and HEAD only. chi's default 405
	// carries no Allow header, so this group supplies its own.
	staticFiles := http.StripPrefix(
		"/s", http.FileServer(http.FS(static.Static)),
	)

	s.router.Route("/s", func(r chi.Router) {
		r.MethodNotAllowed(func(w http.ResponseWriter, _ *http.Request) {
			w.Header().Set("Allow", "GET, HEAD")
			http.Error(
				w,
				"Method Not Allowed",
				http.StatusMethodNotAllowed,
			)
		})
		r.Method(http.MethodGet, "/*", staticFiles)
		r.Method(http.MethodHead, "/*", staticFiles)
	})

	s.router.Route("/api/v1", func(_ chi.Router) {
		// API routes will be added here.
	})

	s.router.Get(
		"/.well-known/healthcheck",
		s.h.HandleHealthCheck(),
	)

	// Authenticated /metrics route. The condition is
	// Config.MetricsAuthEnabled and never the username alone: a
	// username with an empty password would otherwise mount the
	// endpoint behind a credential map that accepts an empty
	// password. Config rejects that combination at startup, and
	// this reads the same value the startup log reports, so the
	// two cannot disagree about whether the route exists.
	if s.params.Config.MetricsAuthEnabled() {
		s.router.Group(func(r chi.Router) {
			r.Use(s.mw.MetricsAuth())
			r.Get("/metrics", s.h.HandleMetrics())
		})
	}

	s.setupPageRoutes()
	s.setupUserRoutes()
	s.setupSourceRoutes()
	s.setupWebhookRoutes()
}

func (s *Server) setupPageRoutes() {
	s.router.Route("/pages", func(r chi.Router) {
		s.recoverPanics(
			r, s.h.HandleErrorPage(http.StatusInternalServerError),
		)
		// MaxBodySize precedes CSRF and RequireAuth deliberately;
		// see maxFormBodySize for why, and for what it costs.
		r.Use(s.mw.MaxBodySize(maxFormBodySize))
		r.Use(s.mw.CSRF(s.h.HandleErrorPage(http.StatusForbidden)))
		r.Use(s.mw.NoCache())

		// The login POST carries no pre-emptive rate limiter. Behind
		// the reverse proxy production requires, when TRUSTED_PROXIES
		// does not cover it, every client shares one bucket, so a
		// limiter spent on arrival lets any stranger deny the operator
		// the only administrative path. The handler verifies
		// credentials first and charges only failures; see
		// Handlers.authenticateUser.
		r.Get("/login", s.h.HandleLoginPage())
		r.Post("/login", s.h.HandleLoginSubmit())

		r.Post("/logout", s.h.HandleLogout())
	})
}

func (s *Server) setupUserRoutes() {
	s.router.Route("/user/{username}", func(r chi.Router) {
		s.recoverPanics(
			r, s.h.HandleErrorPage(http.StatusInternalServerError),
		)
		// MaxBodySize precedes CSRF and RequireAuth deliberately;
		// see maxFormBodySize for why, and for what it costs.
		r.Use(s.mw.MaxBodySize(maxFormBodySize))
		r.Use(s.mw.CSRF(s.h.HandleErrorPage(http.StatusForbidden)))
		r.Use(s.mw.NoCache())
		r.Use(s.mw.RequireAuth())
		r.Get("/", s.h.HandleProfile())
		r.With(s.mw.PasswordChangeRateLimit()).Post(
			"/password", s.h.HandlePasswordChange(),
		)
	})
}

func (s *Server) setupSourceRoutes() {
	s.router.Route("/hooks", func(r chi.Router) {
		s.recoverPanics(
			r, s.h.HandleErrorPage(http.StatusInternalServerError),
		)
		// MaxBodySize precedes CSRF and RequireAuth deliberately;
		// see maxFormBodySize for why, and for what it costs.
		r.Use(s.mw.MaxBodySize(maxFormBodySize))
		r.Use(s.mw.CSRF(s.h.HandleErrorPage(http.StatusForbidden)))
		r.Use(s.mw.NoCache())
		r.Use(s.mw.RequireAuth())
		r.Get("/", s.h.HandleSourceList())
		r.Get("/new", s.h.HandleSourceCreate())
		r.Post("/new", s.h.HandleSourceCreateSubmit())
	})

	s.router.Route("/hook/{sourceID}", func(r chi.Router) {
		s.recoverPanics(
			r, s.h.HandleErrorPage(http.StatusInternalServerError),
		)
		// MaxBodySize precedes CSRF and RequireAuth deliberately;
		// see maxFormBodySize for why, and for what it costs.
		r.Use(s.mw.MaxBodySize(maxFormBodySize))
		r.Use(s.mw.CSRF(s.h.HandleErrorPage(http.StatusForbidden)))
		r.Use(s.mw.NoCache())
		r.Use(s.mw.RequireAuth())
		r.Get("/", s.h.HandleSourceDetail())
		r.Get("/edit", s.h.HandleSourceEdit())
		r.Post("/edit", s.h.HandleSourceEditSubmit())
		r.Post("/delete", s.h.HandleSourceDelete())
		r.Get("/events", s.h.HandleSourceLogs())
		// The log page renders each body only up to its cap, so
		// this is the only route that serves a whole one. It
		// belongs to this group for its RequireAuth and
		// NoCache; see HandleEventBodyDownload for the headers
		// that keep the bytes it returns inert.
		r.Get(
			"/events/{eventID}/body",
			s.h.HandleEventBodyDownload(),
		)
		// Replay is the one page action that queues outbound work:
		// it creates a delivery from a stored event and hands it to
		// the delivery engine. The rate limit is what bounds a
		// held-down button or a scripted loop; the handler
		// separately refuses a replay while an earlier one for the
		// same event and target is still in flight. POST only, so
		// the action cannot be taken by a link, a prefetch or an
		// image tag.
		r.With(s.mw.ReplayRateLimit()).Post(
			"/deliveries/{deliveryID}/replay",
			s.h.HandleDeliveryReplay(),
		)
		// Resubmit is the other page action that queues outbound
		// work: it copies a stored event into a new one and fans
		// that out to every currently active target. It is
		// deliberately repeatable, so the rate limit is the only
		// bound on a held-down button; it gets its own bucket so
		// that spending it does not also disable replay. POST
		// only, so the action cannot be taken by a link, a
		// prefetch or an image tag.
		r.With(s.mw.ResubmitRateLimit()).Post(
			"/events/{eventID}/resubmit",
			s.h.HandleEventResubmit(),
		)
		r.Post(
			"/entrypoints",
			s.h.HandleEntrypointCreate(),
		)
		r.Post(
			"/entrypoints/{entrypointID}/delete",
			s.h.HandleEntrypointDelete(),
		)
		r.Post(
			"/entrypoints/{entrypointID}/toggle",
			s.h.HandleEntrypointToggle(),
		)
		r.Post("/targets", s.h.HandleTargetCreate())
		// The edit form is the one page that renders a target's
		// destination URL and header values in full; see
		// delivery.TargetConfigForm. It belongs to this group for
		// its RequireAuth and NoCache, which are what keep that
		// exception from reaching an unauthenticated request or a
		// shared cache.
		r.Get(
			"/targets/{targetID}/edit",
			s.h.HandleTargetEdit(),
		)
		r.Post(
			"/targets/{targetID}/edit",
			s.h.HandleTargetEditSubmit(),
		)
		r.Post(
			"/targets/{targetID}/delete",
			s.h.HandleTargetDelete(),
		)
		r.Post(
			"/targets/{targetID}/toggle",
			s.h.HandleTargetToggle(),
		)
	})
}

func (s *Server) setupWebhookRoutes() {
	s.router.With(s.mw.ReceiverRateLimit()).HandleFunc(
		"/h/{uuid}",
		s.h.HandleWebhook(),
	)
}