server.go

Documentation: net/http/httptest

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Implementation of Server
     6  
     7  package httptest
     8  
     9  import (
    10  	"crypto/tls"
    11  	"crypto/x509"
    12  	"flag"
    13  	"fmt"
    14  	"log"
    15  	"net"
    16  	"net/http"
    17  	"net/http/internal"
    18  	"os"
    19  	"strings"
    20  	"sync"
    21  	"time"
    22  )
    23  
    24  // A Server is an HTTP server listening on a system-chosen port on the
    25  // local loopback interface, for use in end-to-end HTTP tests.
    26  type Server struct {
    27  	URL      string // base URL of form http://ipaddr:port with no trailing slash
    28  	Listener net.Listener
    29  
    30  	// EnableHTTP2 controls whether HTTP/2 is enabled
    31  	// on the server. It must be set between calling
    32  	// NewUnstartedServer and calling Server.StartTLS.
    33  	EnableHTTP2 bool
    34  
    35  	// TLS is the optional TLS configuration, populated with a new config
    36  	// after TLS is started. If set on an unstarted server before StartTLS
    37  	// is called, existing fields are copied into the new config.
    38  	TLS *tls.Config
    39  
    40  	// Config may be changed after calling NewUnstartedServer and
    41  	// before Start or StartTLS.
    42  	Config *http.Server
    43  
    44  	// certificate is a parsed version of the TLS config certificate, if present.
    45  	certificate *x509.Certificate
    46  
    47  	// wg counts the number of outstanding HTTP requests on this server.
    48  	// Close blocks until all requests are finished.
    49  	wg sync.WaitGroup
    50  
    51  	mu     sync.Mutex // guards closed and conns
    52  	closed bool
    53  	conns  map[net.Conn]http.ConnState // except terminal states
    54  
    55  	// client is configured for use with the server.
    56  	// Its transport is automatically closed when Close is called.
    57  	client *http.Client
    58  }
    59  
    60  func newLocalListener() net.Listener {
    61  	if serveFlag != "" {
    62  		l, err := net.Listen("tcp", serveFlag)
    63  		if err != nil {
    64  			panic(fmt.Sprintf("httptest: failed to listen on %v: %v", serveFlag, err))
    65  		}
    66  		return l
    67  	}
    68  	l, err := net.Listen("tcp", "127.0.0.1:0")
    69  	if err != nil {
    70  		if l, err = net.Listen("tcp6", "[::1]:0"); err != nil {
    71  			panic(fmt.Sprintf("httptest: failed to listen on a port: %v", err))
    72  		}
    73  	}
    74  	return l
    75  }
    76  
    77  // When debugging a particular http server-based test,
    78  // this flag lets you run
    79  //	go test -run=BrokenTest -httptest.serve=127.0.0.1:8000
    80  // to start the broken server so you can interact with it manually.
    81  // We only register this flag if it looks like the caller knows about it
    82  // and is trying to use it as we don't want to pollute flags and this
    83  // isn't really part of our API. Don't depend on this.
    84  var serveFlag string
    85  
    86  func init() {
    87  	if strSliceContainsPrefix(os.Args, "-httptest.serve=") || strSliceContainsPrefix(os.Args, "--httptest.serve=") {
    88  		flag.StringVar(&serveFlag, "httptest.serve", "", "if non-empty, httptest.NewServer serves on this address and blocks.")
    89  	}
    90  }
    91  
    92  func strSliceContainsPrefix(v []string, pre string) bool {
    93  	for _, s := range v {
    94  		if strings.HasPrefix(s, pre) {
    95  			return true
    96  		}
    97  	}
    98  	return false
    99  }
   100  
   101  // NewServer starts and returns a new Server.
   102  // The caller should call Close when finished, to shut it down.
   103  func NewServer(handler http.Handler) *Server {
   104  	ts := NewUnstartedServer(handler)
   105  	ts.Start()
   106  	return ts
   107  }
   108  
   109  // NewUnstartedServer returns a new Server but doesn't start it.
   110  //
   111  // After changing its configuration, the caller should call Start or
   112  // StartTLS.
   113  //
   114  // The caller should call Close when finished, to shut it down.
   115  func NewUnstartedServer(handler http.Handler) *Server {
   116  	return &Server{
   117  		Listener: newLocalListener(),
   118  		Config:   &http.Server{Handler: handler},
   119  	}
   120  }
   121  
   122  // Start starts a server from NewUnstartedServer.
   123  func (s *Server) Start() {
   124  	if s.URL != "" {
   125  		panic("Server already started")
   126  	}
   127  	if s.client == nil {
   128  		s.client = &http.Client{Transport: &http.Transport{}}
   129  	}
   130  	s.URL = "http://" + s.Listener.Addr().String()
   131  	s.wrap()
   132  	s.goServe()
   133  	if serveFlag != "" {
   134  		fmt.Fprintln(os.Stderr, "httptest: serving on", s.URL)
   135  		select {}
   136  	}
   137  }
   138  
   139  // StartTLS starts TLS on a server from NewUnstartedServer.
   140  func (s *Server) StartTLS() {
   141  	if s.URL != "" {
   142  		panic("Server already started")
   143  	}
   144  	if s.client == nil {
   145  		s.client = &http.Client{Transport: &http.Transport{}}
   146  	}
   147  	cert, err := tls.X509KeyPair(internal.LocalhostCert, internal.LocalhostKey)
   148  	if err != nil {
   149  		panic(fmt.Sprintf("httptest: NewTLSServer: %v", err))
   150  	}
   151  
   152  	existingConfig := s.TLS
   153  	if existingConfig != nil {
   154  		s.TLS = existingConfig.Clone()
   155  	} else {
   156  		s.TLS = new(tls.Config)
   157  	}
   158  	if s.TLS.NextProtos == nil {
   159  		nextProtos := []string{"http/1.1"}
   160  		if s.EnableHTTP2 {
   161  			nextProtos = []string{"h2"}
   162  		}
   163  		s.TLS.NextProtos = nextProtos
   164  	}
   165  	if len(s.TLS.Certificates) == 0 {
   166  		s.TLS.Certificates = []tls.Certificate{cert}
   167  	}
   168  	s.certificate, err = x509.ParseCertificate(s.TLS.Certificates[0].Certificate[0])
   169  	if err != nil {
   170  		panic(fmt.Sprintf("httptest: NewTLSServer: %v", err))
   171  	}
   172  	certpool := x509.NewCertPool()
   173  	certpool.AddCert(s.certificate)
   174  	s.client.Transport = &http.Transport{
   175  		TLSClientConfig: &tls.Config{
   176  			RootCAs: certpool,
   177  		},
   178  		ForceAttemptHTTP2: s.EnableHTTP2,
   179  	}
   180  	s.Listener = tls.NewListener(s.Listener, s.TLS)
   181  	s.URL = "https://" + s.Listener.Addr().String()
   182  	s.wrap()
   183  	s.goServe()
   184  }
   185  
   186  // NewTLSServer starts and returns a new Server using TLS.
   187  // The caller should call Close when finished, to shut it down.
   188  func NewTLSServer(handler http.Handler) *Server {
   189  	ts := NewUnstartedServer(handler)
   190  	ts.StartTLS()
   191  	return ts
   192  }
   193  
   194  type closeIdleTransport interface {
   195  	CloseIdleConnections()
   196  }
   197  
   198  // Close shuts down the server and blocks until all outstanding
   199  // requests on this server have completed.
   200  func (s *Server) Close() {
   201  	s.mu.Lock()
   202  	if !s.closed {
   203  		s.closed = true
   204  		s.Listener.Close()
   205  		s.Config.SetKeepAlivesEnabled(false)
   206  		for c, st := range s.conns {
   207  			// Force-close any idle connections (those between
   208  			// requests) and new connections (those which connected
   209  			// but never sent a request). StateNew connections are
   210  			// super rare and have only been seen (in
   211  			// previously-flaky tests) in the case of
   212  			// socket-late-binding races from the http Client
   213  			// dialing this server and then getting an idle
   214  			// connection before the dial completed. There is thus
   215  			// a connected connection in StateNew with no
   216  			// associated Request. We only close StateIdle and
   217  			// StateNew because they're not doing anything. It's
   218  			// possible StateNew is about to do something in a few
   219  			// milliseconds, but a previous CL to check again in a
   220  			// few milliseconds wasn't liked (early versions of
   221  			// https://golang.org/cl/15151) so now we just
   222  			// forcefully close StateNew. The docs for Server.Close say
   223  			// we wait for "outstanding requests", so we don't close things
   224  			// in StateActive.
   225  			if st == http.StateIdle || st == http.StateNew {
   226  				s.closeConn(c)
   227  			}
   228  		}
   229  		// If this server doesn't shut down in 5 seconds, tell the user why.
   230  		t := time.AfterFunc(5*time.Second, s.logCloseHangDebugInfo)
   231  		defer t.Stop()
   232  	}
   233  	s.mu.Unlock()
   234  
   235  	// Not part of httptest.Server's correctness, but assume most
   236  	// users of httptest.Server will be using the standard
   237  	// transport, so help them out and close any idle connections for them.
   238  	if t, ok := http.DefaultTransport.(closeIdleTransport); ok {
   239  		t.CloseIdleConnections()
   240  	}
   241  
   242  	// Also close the client idle connections.
   243  	if s.client != nil {
   244  		if t, ok := s.client.Transport.(closeIdleTransport); ok {
   245  			t.CloseIdleConnections()
   246  		}
   247  	}
   248  
   249  	s.wg.Wait()
   250  }
   251  
   252  func (s *Server) logCloseHangDebugInfo() {
   253  	s.mu.Lock()
   254  	defer s.mu.Unlock()
   255  	var buf strings.Builder
   256  	buf.WriteString("httptest.Server blocked in Close after 5 seconds, waiting for connections:\n")
   257  	for c, st := range s.conns {
   258  		fmt.Fprintf(&buf, "  %T %p %v in state %v\n", c, c, c.RemoteAddr(), st)
   259  	}
   260  	log.Print(buf.String())
   261  }
   262  
   263  // CloseClientConnections closes any open HTTP connections to the test Server.
   264  func (s *Server) CloseClientConnections() {
   265  	s.mu.Lock()
   266  	nconn := len(s.conns)
   267  	ch := make(chan struct{}, nconn)
   268  	for c := range s.conns {
   269  		go s.closeConnChan(c, ch)
   270  	}
   271  	s.mu.Unlock()
   272  
   273  	// Wait for outstanding closes to finish.
   274  	//
   275  	// Out of paranoia for making a late change in Go 1.6, we
   276  	// bound how long this can wait, since golang.org/issue/14291
   277  	// isn't fully understood yet. At least this should only be used
   278  	// in tests.
   279  	timer := time.NewTimer(5 * time.Second)
   280  	defer timer.Stop()
   281  	for i := 0; i < nconn; i++ {
   282  		select {
   283  		case <-ch:
   284  		case <-timer.C:
   285  			// Too slow. Give up.
   286  			return
   287  		}
   288  	}
   289  }
   290  
   291  // Certificate returns the certificate used by the server, or nil if
   292  // the server doesn't use TLS.
   293  func (s *Server) Certificate() *x509.Certificate {
   294  	return s.certificate
   295  }
   296  
   297  // Client returns an HTTP client configured for making requests to the server.
   298  // It is configured to trust the server's TLS test certificate and will
   299  // close its idle connections on Server.Close.
   300  func (s *Server) Client() *http.Client {
   301  	return s.client
   302  }
   303  
   304  func (s *Server) goServe() {
   305  	s.wg.Add(1)
   306  	go func() {
   307  		defer s.wg.Done()
   308  		s.Config.Serve(s.Listener)
   309  	}()
   310  }
   311  
   312  // wrap installs the connection state-tracking hook to know which
   313  // connections are idle.
   314  func (s *Server) wrap() {
   315  	oldHook := s.Config.ConnState
   316  	s.Config.ConnState = func(c net.Conn, cs http.ConnState) {
   317  		s.mu.Lock()
   318  		defer s.mu.Unlock()
   319  		switch cs {
   320  		case http.StateNew:
   321  			s.wg.Add(1)
   322  			if _, exists := s.conns[c]; exists {
   323  				panic("invalid state transition")
   324  			}
   325  			if s.conns == nil {
   326  				s.conns = make(map[net.Conn]http.ConnState)
   327  			}
   328  			s.conns[c] = cs
   329  			if s.closed {
   330  				// Probably just a socket-late-binding dial from
   331  				// the default transport that lost the race (and
   332  				// thus this connection is now idle and will
   333  				// never be used).
   334  				s.closeConn(c)
   335  			}
   336  		case http.StateActive:
   337  			if oldState, ok := s.conns[c]; ok {
   338  				if oldState != http.StateNew && oldState != http.StateIdle {
   339  					panic("invalid state transition")
   340  				}
   341  				s.conns[c] = cs
   342  			}
   343  		case http.StateIdle:
   344  			if oldState, ok := s.conns[c]; ok {
   345  				if oldState != http.StateActive {
   346  					panic("invalid state transition")
   347  				}
   348  				s.conns[c] = cs
   349  			}
   350  			if s.closed {
   351  				s.closeConn(c)
   352  			}
   353  		case http.StateHijacked, http.StateClosed:
   354  			s.forgetConn(c)
   355  		}
   356  		if oldHook != nil {
   357  			oldHook(c, cs)
   358  		}
   359  	}
   360  }
   361  
   362  // closeConn closes c.
   363  // s.mu must be held.
   364  func (s *Server) closeConn(c net.Conn) { s.closeConnChan(c, nil) }
   365  
   366  // closeConnChan is like closeConn, but takes an optional channel to receive a value
   367  // when the goroutine closing c is done.
   368  func (s *Server) closeConnChan(c net.Conn, done chan<- struct{}) {
   369  	c.Close()
   370  	if done != nil {
   371  		done <- struct{}{}
   372  	}
   373  }
   374  
   375  // forgetConn removes c from the set of tracked conns and decrements it from the
   376  // waitgroup, unless it was previously removed.
   377  // s.mu must be held.
   378  func (s *Server) forgetConn(c net.Conn) {
   379  	if _, ok := s.conns[c]; ok {
   380  		delete(s.conns, c)
   381  		s.wg.Done()
   382  	}
   383  }
   384
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