Add db-connect, a SQL over HTTPS server

dbconnect/proxy.go

@@ -0,0 +1,271 @@
+package dbconnect
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/cloudflare/cloudflared/hello"
+	"github.com/cloudflare/cloudflared/validation"
+	"github.com/gorilla/mux"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// Proxy is an HTTP server that proxies requests to a Client.
+type Proxy struct {
+	client          Client
+	accessValidator *validation.Access
+	logger          *logrus.Logger
+}
+
+// NewInsecureProxy creates a Proxy that talks to a Client at an origin.
+//
+// In insecure mode, the Proxy will allow all Command requests.
+func NewInsecureProxy(ctx context.Context, origin string) (*Proxy, error) {
+	originURL, err := url.Parse(origin)
+	if err != nil {
+		return nil, errors.Wrap(err, "must provide a valid database url")
+	}
+
+	client, err := NewClient(ctx, originURL)
+	if err != nil {
+		return nil, err
+	}
+
+	err = client.Ping(ctx)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not connect to the database")
+	}
+
+	return &Proxy{client, nil, logrus.New()}, nil
+}
+
+// NewSecureProxy creates a Proxy that talks to a Client at an origin.
+//
+// In secure mode, the Proxy will reject any Command requests that are
+// not authenticated by Cloudflare Access with a valid JWT.
+func NewSecureProxy(ctx context.Context, origin, authDomain, applicationAUD string) (*Proxy, error) {
+	proxy, err := NewInsecureProxy(ctx, origin)
+	if err != nil {
+		return nil, err
+	}
+
+	validator, err := validation.NewAccessValidator(ctx, authDomain, authDomain, applicationAUD)
+	if err != nil {
+		return nil, err
+	}
+
+	proxy.accessValidator = validator
+
+	return proxy, err
+}
+
+// IsInsecure gets whether the Proxy will accept a Command from any source.
+func (proxy *Proxy) IsInsecure() bool {
+	return proxy.accessValidator == nil
+}
+
+// IsAllowed checks whether a http.Request is allowed to receive data.
+//
+// By default, requests must pass through Cloudflare Access for authentication.
+// If the proxy is explcitly set to insecure mode, all requests will be allowed.
+func (proxy *Proxy) IsAllowed(r *http.Request, verbose ...bool) bool {
+	if proxy.IsInsecure() {
+		return true
+	}
+
+	// Access and Tunnel should prevent bad JWTs from even reaching the origin,
+	// but validate tokens anyway as an abundance of caution.
+	err := proxy.accessValidator.ValidateRequest(r.Context(), r)
+	if err == nil {
+		return true
+	}
+
+	// Warn administrators that invalid JWTs are being rejected. This is indicative
+	// of either a misconfiguration of the CLI or a massive failure of upstream systems.
+	if len(verbose) > 0 {
+		proxy.httpLog(r, err).Error("Failed JWT authentication")
+	}
+
+	return false
+}
+
+// Start the Proxy at a given address and notify the listener channel when the server is online.
+func (proxy *Proxy) Start(ctx context.Context, addr string, listenerC chan<- net.Listener) error {
+	// STOR-611: use a seperate listener and consider web socket support.
+	httpListener, err := hello.CreateTLSListener(addr)
+	if err != nil {
+		return errors.Wrapf(err, "could not create listener at %s", addr)
+	}
+
+	errC := make(chan error)
+	defer close(errC)
+
+	// Starts the HTTP server and begins to serve requests.
+	go func() {
+		errC <- proxy.httpListen(ctx, httpListener)
+	}()
+
+	// Continually ping the server until it comes online or 10 attempts fail.
+	go func() {
+		var err error
+		for i := 0; i < 10; i++ {
+			_, err = http.Get("http://" + httpListener.Addr().String())
+
+			// Once no error was detected, notify the listener channel and return.
+			if err == nil {
+				listenerC <- httpListener
+				return
+			}
+
+			// Backoff between requests to ping the server.
+			<-time.After(1 * time.Second)
+		}
+		errC <- errors.Wrap(err, "took too long for the http server to start")
+	}()
+
+	return <-errC
+}
+
+// httpListen starts the httpServer and blocks until the context closes.
+func (proxy *Proxy) httpListen(ctx context.Context, listener net.Listener) error {
+	httpServer := &http.Server{
+		Addr:         listener.Addr().String(),
+		Handler:      proxy.httpRouter(),
+		ReadTimeout:  10 * time.Second,
+		WriteTimeout: 60 * time.Second,
+		IdleTimeout:  60 * time.Second,
+	}
+
+	go func() {
+		<-ctx.Done()
+		httpServer.Close()
+		listener.Close()
+	}()
+
+	return httpServer.Serve(listener)
+}
+
+// httpRouter creates a mux.Router for the Proxy.
+func (proxy *Proxy) httpRouter() *mux.Router {
+	router := mux.NewRouter()
+
+	router.HandleFunc("/ping", proxy.httpPing()).Methods("GET", "HEAD")
+	router.HandleFunc("/submit", proxy.httpSubmit()).Methods("POST")
+
+	return router
+}
+
+// httpPing tests the connection to the database.
+//
+// By default, this endpoint is unauthenticated to allow for health checks.
+// To enable authentication, Cloudflare Access must be enabled on this route.
+func (proxy *Proxy) httpPing() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		ctx := r.Context()
+		err := proxy.client.Ping(ctx)
+
+		if err == nil {
+			proxy.httpRespond(w, r, http.StatusOK, "")
+		} else {
+			proxy.httpRespondErr(w, r, http.StatusInternalServerError, err)
+		}
+	}
+}
+
+// httpSubmit sends a command to the database and returns its response.
+//
+// By default, this endpoint will reject requests that do not pass through Cloudflare Access.
+// To disable authentication, the --insecure flag must be specified in the command line.
+func (proxy *Proxy) httpSubmit() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if !proxy.IsAllowed(r, true) {
+			proxy.httpRespondErr(w, r, http.StatusForbidden, fmt.Errorf(""))
+			return
+		}
+
+		var cmd Command
+		err := json.NewDecoder(r.Body).Decode(&cmd)
+		if err != nil {
+			proxy.httpRespondErr(w, r, http.StatusBadRequest, err)
+			return
+		}
+
+		ctx := r.Context()
+		data, err := proxy.client.Submit(ctx, &cmd)
+
+		if err != nil {
+			proxy.httpRespondErr(w, r, http.StatusUnprocessableEntity, err)
+			return
+		}
+
+		w.Header().Set("Content-type", "application/json")
+		err = json.NewEncoder(w).Encode(data)
+		if err != nil {
+			proxy.httpRespondErr(w, r, http.StatusInternalServerError, err)
+		}
+	}
+}
+
+// httpRespond writes a status code and string response to the response writer.
+func (proxy *Proxy) httpRespond(w http.ResponseWriter, r *http.Request, status int, message string) {
+	w.WriteHeader(status)
+
+	// Only expose the message detail of the reponse if the request is not HEAD
+	// and the user is authenticated. For example, this prevents an unauthenticated
+	// failed health check from accidentally leaking sensitive information about the Client.
+	if r.Method != http.MethodHead && proxy.IsAllowed(r) {
+		if message == "" {
+			message = http.StatusText(status)
+		}
+		fmt.Fprint(w, message)
+	}
+}
+
+// httpRespondErr is similar to httpRespond, except it formats errors to be more friendly.
+func (proxy *Proxy) httpRespondErr(w http.ResponseWriter, r *http.Request, defaultStatus int, err error) {
+	status, err := httpError(defaultStatus, err)
+
+	proxy.httpRespond(w, r, status, err.Error())
+	if len(err.Error()) > 0 {
+		proxy.httpLog(r, err).Warn("Database proxy error")
+	}
+}
+
+// httpLog returns a logrus.Entry that is formatted to output a request Cf-ray.
+func (proxy *Proxy) httpLog(r *http.Request, err error) *logrus.Entry {
+	return proxy.logger.WithContext(r.Context()).WithField("CF-RAY", r.Header.Get("Cf-ray")).WithError(err)
+}
+
+// httpError extracts common errors and returns an status code and friendly error.
+func httpError(defaultStatus int, err error) (int, error) {
+	if err == nil {
+		return http.StatusNotImplemented, fmt.Errorf("error expected but found none")
+	}
+
+	if err == io.EOF {
+		return http.StatusBadRequest, fmt.Errorf("request body cannot be empty")
+	}
+
+	if err == context.DeadlineExceeded {
+		return http.StatusRequestTimeout, err
+	}
+
+	_, ok := err.(net.Error)
+	if ok {
+		return http.StatusRequestTimeout, err
+	}
+
+	if err == context.Canceled {
+		// Does not exist in Golang, but would be: http.StatusClientClosedWithoutResponse
+		return 444, err
+	}
+
+	return defaultStatus, err
+}