git » gofer » master » tree

[master] / server / http.go

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
package server

import (
	"context"
	"crypto/tls"
	"errors"
	"fmt"
	"io"
	golog "log"
	"net/http"
	"net/http/cgi"
	"net/http/httputil"
	"net/url"
	"strings"
	"time"

	"blitiri.com.ar/go/gofer/config"
	"blitiri.com.ar/go/gofer/reqlog"
	"blitiri.com.ar/go/gofer/trace"
	"blitiri.com.ar/go/gofer/util"
	"blitiri.com.ar/go/log"
	"blitiri.com.ar/go/systemd"
)

func httpServer(addr string, conf config.HTTP) (*http.Server, error) {
	tr := trace.New("httpserver", addr)
	tr.SetMaxEvents(1000)

	srv := &http.Server{
		Addr: addr,

		ReadTimeout:  60 * time.Second,
		WriteTimeout: 60 * time.Second,

		ErrorLog: golog.New(tr, "", golog.Lshortfile),
	}

	mux := http.NewServeMux()
	srv.Handler = mux

	// Load route table.
	for path, r := range conf.Routes {
		if r.Dir != "" {
			log.Infof("%s route %q -> dir %q", srv.Addr, path, r.Dir)
			mux.Handle(path, makeDir(path, r.Dir, r.DirOpts))
		} else if r.File != "" {
			log.Infof("%s route %q -> file %q", srv.Addr, path, r.File)
			mux.Handle(path, makeFile(path, r.File))
		} else if r.Proxy != nil {
			log.Infof("%s route %q -> proxy %s", srv.Addr, path, r.Proxy)
			mux.Handle(path, makeProxy(path, r.Proxy.URL()))
		} else if r.Redirect != nil {
			log.Infof("%s route %q -> redirect %s", srv.Addr, path, r.Redirect)
			mux.Handle(path, makeRedirect(path, r.Redirect.URL()))
		} else if len(r.CGI) > 0 {
			log.Infof("%s route %q -> cgi %q", srv.Addr, path, r.CGI)
			mux.Handle(path, makeCGI(path, r.CGI))
		} else if r.Status > 0 {
			log.Infof("%s route %q -> status %d", srv.Addr, path, r.Status)
			mux.Handle(path, makeStatus(path, r.Status))
		}
	}

	// Wrap the authentication handlers.
	if len(conf.Auth) > 0 {
		authMux := http.NewServeMux()
		for path, dbPath := range conf.Auth {
			users, err := LoadAuthFile(dbPath)
			if err != nil {
				return nil, log.Errorf(
					"failed to load auth file %q: %v", dbPath, err)
			}
			authMux.Handle(path,
				&AuthWrapper{
					handler: srv.Handler,
					users:   users,
				})

			log.Infof("%s auth %q -> %q", srv.Addr, path, dbPath)
		}

		if _, ok := conf.Auth["/"]; !ok {
			authMux.Handle("/", srv.Handler)
		}
		srv.Handler = authMux
	}

	// Extra headers.
	if len(conf.SetHeader) > 0 {
		hdrMux := http.NewServeMux()
		for path, extraHdrs := range conf.SetHeader {
			hdrMux.Handle(path, SetHeader(srv.Handler, extraHdrs))
			log.Infof("%s add headers %q -> %q", srv.Addr, path, extraHdrs)
		}

		if _, ok := conf.SetHeader["/"]; !ok {
			hdrMux.Handle("/", srv.Handler)
		}
		srv.Handler = hdrMux
	}

	// Logging for all entries.
	// Because this will use the request logs if available, it needs to be
	// wrapped by it.
	srv.Handler = WithLogging(srv.Handler)

	if len(conf.ReqLog) > 0 {
		logMux := http.NewServeMux()
		for path, logName := range conf.ReqLog {
			l := reqlog.FromName(logName)
			if l == nil {
				return nil, log.Errorf("unknown reqlog name %q", logName)
			}
			logMux.Handle(path, WithReqLog(srv.Handler, l))
			log.Infof("%s reqlog %q to %q", srv.Addr, path, logName)
		}

		if _, ok := conf.ReqLog["/"]; !ok {
			logMux.Handle("/", srv.Handler)
		}
		srv.Handler = logMux
	}

	// Tracing for all entries.
	srv.Handler = WithTrace("http@"+srv.Addr, srv.Handler)

	return srv, nil
}

func HTTP(addr string, conf config.HTTP) error {
	srv, err := httpServer(addr, conf)
	if err != nil {
		return err
	}
	lis, err := systemd.Listen("tcp", addr)
	if err != nil {
		return log.Errorf("%s error listening: %v", addr, err)
	}
	log.Infof("%s http starting on %q", addr, lis.Addr())
	err = srv.Serve(lis)
	return log.Errorf("%s http exited: %v", addr, err)
}

func HTTPS(addr string, conf config.HTTPS) error {
	srv, err := httpServer(addr, conf.HTTP)
	if err != nil {
		return err
	}

	srv.TLSConfig, err = util.LoadCertsForHTTPS(conf)
	if err != nil {
		return log.Errorf("%s error loading certs: %v", addr, err)
	}

	rawLis, err := systemd.Listen("tcp", addr)
	if err != nil {
		return log.Errorf("%s error listening: %v", addr, err)
	}

	lis := tls.NewListener(rawLis, srv.TLSConfig)

	log.Infof("%s https starting on %q", addr, lis.Addr())
	err = srv.Serve(lis)
	return log.Errorf("%s https exited: %v", addr, err)
}

// joinPath joins to HTTP paths. We can't use path.Join because it strips the
// final "/", which may have meaning in URLs.
func joinPath(a, b string) string {
	if a == "" && b == "" {
		return "/"
	}
	if a == "" || b == "" {
		return a + b
	}
	if strings.HasSuffix(a, "/") && strings.HasPrefix(b, "/") {
		return strings.TrimSuffix(a, "/") + b
	}
	if !strings.HasSuffix(a, "/") && !strings.HasPrefix(b, "/") {
		return a + "/" + b
	}

	return a + b
}

func stripDomain(from string) string {
	// Strip the domain from `from`, if any. That is useful for the http
	// router, but to us is irrelevant.
	if idx := strings.Index(from, "/"); idx > 0 {
		from = from[idx:]
	}
	return from
}

func adjustPath(req string, from string, to string) string {
	// Strip "from" from the request path, so that if we have this config:
	//
	//   /a/ -> http://dst/b
	//   /p/q -> http://dst/r/s
	//   www.example.com/t/ -> http://dst/u
	//
	// then:
	//   /a/x  goes to  http://dst/b/x (not http://dst/b/a/x)
	//   /p/q  goes to  http://dst/r/s
	//   www.example.com/t/x  goes to  http://dst/u/x
	//
	// It is expected that `from` already has the domain removed using
	// stripDomain.
	//
	// If req doesn't have from as prefix, then we panic.
	if !strings.HasPrefix(req, from) {
		panic(fmt.Errorf(
			"adjustPath(req=%q, from=%q, to=%q): from is not prefix",
			req, from, to))
	}

	dst := joinPath(to, strings.TrimPrefix(req, from))
	if dst == "" || dst[0] != '/' {
		dst = "/" + dst
	}
	return dst
}

func makeDir(path string, dir string, opts config.DirOpts) http.Handler {
	fs := FileServer(NewFS(http.Dir(dir), opts))

	path = stripDomain(path)
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tr, _ := trace.FromContext(r.Context())
		tr.Printf("serving dir root %q", dir)

		r.URL.Path = strings.TrimPrefix(r.URL.Path, path)
		if r.URL.Path == "" || r.URL.Path[0] != '/' {
			r.URL.Path = "/" + r.URL.Path
		}
		tr.Printf("adjusted dir: %q", r.URL.Path)
		fs.ServeHTTP(w, r)
	})
}

func makeFile(path string, file string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tr, _ := trace.FromContext(r.Context())
		tr.Printf("serving file %q", file)
		http.ServeFile(w, r, file)
	})
}

func makeCGI(path string, cmd []string) http.Handler {
	path = stripDomain(path)
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tr, _ := trace.FromContext(r.Context())
		tr.Printf("exec %q", cmd)
		h := cgi.Handler{
			Path:   cmd[0],
			Args:   cmd[1:],
			Root:   path,
			Logger: golog.New(tr, "", golog.Lshortfile),
			Stderr: tr,
		}
		h.ServeHTTP(w, r)
	})
}

func makeRedirect(path string, to url.URL) http.Handler {
	path = stripDomain(path)

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tr, _ := trace.FromContext(r.Context())
		target := to
		target.RawQuery = r.URL.RawQuery
		target.Path = adjustPath(r.URL.Path, path, to.Path)
		tr.Printf("redirect to %q", target.String())

		http.Redirect(w, r, target.String(), http.StatusTemporaryRedirect)
	})
}

func makeStatus(from string, status int) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tr, _ := trace.FromContext(r.Context())
		tr.Printf("status %d", status)
		w.WriteHeader(status)
	})
}

func makeProxy(path string, to url.URL) http.Handler {
	proxy := &httputil.ReverseProxy{}
	proxy.Transport = &proxyTransport{}

	// Director that strips "path" from the request path, so that if we have
	// this config:
	//
	//   /a/ -> http://dst/b
	//   www.example.com/p/ -> http://dst/q
	//
	// then:
	//   /a/x  goes to  http://dst/b/x (not http://dst/b/a/x)
	//   www.example.com/p/x  goes to  http://dst/q/x

	// Strip the domain from `path`, if any. That is useful for the http
	// router, but to us is irrelevant.
	path = stripDomain(path)

	proxy.Director = func(req *http.Request) {
		req.URL.Scheme = to.Scheme
		req.URL.Host = to.Host
		req.URL.Path = adjustPath(req.URL.Path, path, to.Path)

		// If the user agent is not set, prevent a fall back to the default value.
		if _, ok := req.Header["User-Agent"]; !ok {
			req.Header.Set("User-Agent", "")
		}

		// Strip X-Forwarded-For header, since we don't trust what the client
		// sent, and the reverse proxy will append to.
		req.Header.Del("X-Forwarded-For")

		// Note we don't do this so we can have routes independent of virtual
		// hosts. The downside is that if the destination scheme is HTTPS,
		// this causes issues with the TLS SNI negotiation.
		//req.Host = to.Host
	}

	return newReverseProxy(proxy)
}

type proxyTransport struct{}

func (t *proxyTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	tr, _ := trace.FromContext(req.Context())
	tr.Printf("proxy to: %s %s %s",
		req.Proto, req.Method, req.URL.String())

	response, err := http.DefaultTransport.RoundTrip(req)
	if err == nil {
		tr.Printf("backend response: %s, %d bytes",
			response.Status, response.ContentLength)
		if response.StatusCode >= 400 && response.StatusCode != 404 {
			tr.SetError()
		}
	} else {
		// errorHandler will be invoked when err != nil, avoid double error
		// logging.
	}

	return response, err
}

type reverseProxy struct {
	rp *httputil.ReverseProxy
}

func newReverseProxy(rp *httputil.ReverseProxy) http.Handler {
	p := &reverseProxy{
		rp: rp,
	}
	rp.ErrorHandler = p.errorHandler
	return p
}

func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
	p.rp.ServeHTTP(rw, req)
}

func (p *reverseProxy) errorHandler(w http.ResponseWriter, r *http.Request, err error) {
	tr, _ := trace.FromContext(r.Context())
	tr.Printf("backend error: %v", err)

	// Mark it as an error, unless it was context.Canceled, which is normal:
	// the client side has closed the connection.
	if !errors.Is(err, context.Canceled) {
		tr.SetError()
	}

	w.WriteHeader(http.StatusBadGateway)
}

// Wrapper around http.ResponseWriter so we can extract status and length.
type statusWriter struct {
	http.ResponseWriter
	status int
	length int64
}

func (w *statusWriter) WriteHeader(status int) {
	w.status = status
	w.ResponseWriter.WriteHeader(status)
}

func (w *statusWriter) Write(b []byte) (int, error) {
	n, err := w.ResponseWriter.Write(b)
	w.length += int64(n)
	return n, err
}

// ReadFrom is optional but enables the use of sendfile, which speeds things
// up considerably.
func (w *statusWriter) ReadFrom(src io.Reader) (int64, error) {
	n, err := io.Copy(w.ResponseWriter, src)
	w.length += n
	return n, err
}

// Flush is optional but makes it support the http.Flusher interface, which is
// needed for things like server-side events.
func (w *statusWriter) Flush() {
	flusher, ok := w.ResponseWriter.(http.Flusher)
	if ok {
		flusher.Flush()
	}
}

func SetHeader(parent http.Handler, hdrs map[string]string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tr, _ := trace.FromContext(r.Context())
		for k, v := range hdrs {
			w.Header().Set(k, v)
			tr.Printf("added header: %s: %q", k, v)
		}
		parent.ServeHTTP(w, r)
	})
}

func WithTrace(name string, parent http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tr, ok := trace.FromContext(r.Context())
		if !ok {
			tr = trace.New(name, r.Host+r.URL.String())
			defer tr.Finish()

			// Associate the trace with this request.
			r = r.WithContext(trace.NewContext(r.Context(), tr))

			// Log the request on creation.
			tr.Printf("%s %s %s %s %s",
				r.RemoteAddr, r.Proto, r.Method, r.Host, r.URL.String())
		}

		parent.ServeHTTP(w, r)
	})
}

func WithLogging(parent http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tr, _ := trace.FromContext(r.Context())

		// Wrap the writer so we can get output information.
		sw := statusWriter{ResponseWriter: w}

		// Save the URL, since some of the callers will change it (e.g.
		// makeDir).
		origURL := *r.URL

		start := time.Now()
		parent.ServeHTTP(&sw, r)
		lat := time.Since(start)

		tr.Printf("%d %s", sw.status, http.StatusText(sw.status))
		tr.Printf("%d bytes", sw.length)

		if sw.status >= 400 && sw.status != 404 {
			tr.SetError()
		}

		r.URL = &origURL
		reqLog(r, sw.status, sw.length, lat)
	})
}

func WithReqLog(parent http.Handler, rl *reqlog.Log) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Associate the log with this request. Actual logging will be
		// performed within the handlers (see WithLogging).
		r = r.WithContext(reqlog.NewContext(r.Context(), rl))

		parent.ServeHTTP(w, r)
	})
}

func reqLog(r *http.Request, status int, length int64, latency time.Duration) {
	rlog := reqlog.FromContext(r.Context())
	if rlog == nil {
		return
	}
	rlog.Log(&reqlog.Event{
		T:       time.Now(),
		H:       r,
		Status:  status,
		Length:  length,
		Latency: latency,
	})
}