github.com/akashshinde/docker@v1.9.1/api/server/server.go

package server

import (
	"crypto/tls"
	"net"
	"net/http"
	"os"
	"strings"

	"github.com/Sirupsen/logrus"
	"github.com/docker/docker/api/server/httputils"
	"github.com/docker/docker/api/server/router"
	"github.com/docker/docker/api/server/router/local"
	"github.com/docker/docker/api/server/router/network"
	"github.com/docker/docker/daemon"
	"github.com/docker/docker/pkg/sockets"
	"github.com/docker/docker/utils"
	"github.com/gorilla/mux"
	"golang.org/x/net/context"
)

// versionMatcher defines a variable matcher to be parsed by the router
// when a request is about to be served.
const versionMatcher = "/v{version:[0-9.]+}"

// Config provides the configuration for the API server
type Config struct {
	Logging     bool
	EnableCors  bool
	CorsHeaders string
	Version     string
	SocketGroup string
	TLSConfig   *tls.Config
	Addrs       []Addr
}

// Server contains instance details for the server
type Server struct {
	cfg     *Config
	start   chan struct{}
	servers []*HTTPServer
	routers []router.Router
}

// Addr contains string representation of address and its protocol (tcp, unix...).
type Addr struct {
	Proto string
	Addr  string
}

// New returns a new instance of the server based on the specified configuration.
// It allocates resources which will be needed for ServeAPI(ports, unix-sockets).
func New(cfg *Config) (*Server, error) {
	s := &Server{
		cfg:   cfg,
		start: make(chan struct{}),
	}
	for _, addr := range cfg.Addrs {
		srv, err := s.newServer(addr.Proto, addr.Addr)
		if err != nil {
			return nil, err
		}
		logrus.Debugf("Server created for HTTP on %s (%s)", addr.Proto, addr.Addr)
		s.servers = append(s.servers, srv...)
	}
	return s, nil
}

// Close closes servers and thus stop receiving requests
func (s *Server) Close() {
	for _, srv := range s.servers {
		if err := srv.Close(); err != nil {
			logrus.Error(err)
		}
	}
}

// ServeAPI loops through all initialized servers and spawns goroutine
// with Serve() method for each.
func (s *Server) ServeAPI() error {
	var chErrors = make(chan error, len(s.servers))
	for _, srv := range s.servers {
		go func(srv *HTTPServer) {
			var err error
			logrus.Infof("API listen on %s", srv.l.Addr())
			if err = srv.Serve(); err != nil && strings.Contains(err.Error(), "use of closed network connection") {
				err = nil
			}
			chErrors <- err
		}(srv)
	}

	for i := 0; i < len(s.servers); i++ {
		err := <-chErrors
		if err != nil {
			return err
		}
	}

	return nil
}

// HTTPServer contains an instance of http server and the listener.
// srv *http.Server, contains configuration to create a http server and a mux router with all api end points.
// l   net.Listener, is a TCP or Socket listener that dispatches incoming request to the router.
type HTTPServer struct {
	srv *http.Server
	l   net.Listener
}

// Serve starts listening for inbound requests.
func (s *HTTPServer) Serve() error {
	return s.srv.Serve(s.l)
}

// Close closes the HTTPServer from listening for the inbound requests.
func (s *HTTPServer) Close() error {
	return s.l.Close()
}

func writeCorsHeaders(w http.ResponseWriter, r *http.Request, corsHeaders string) {
	logrus.Debugf("CORS header is enabled and set to: %s", corsHeaders)
	w.Header().Add("Access-Control-Allow-Origin", corsHeaders)
	w.Header().Add("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, X-Registry-Auth")
	w.Header().Add("Access-Control-Allow-Methods", "HEAD, GET, POST, DELETE, PUT, OPTIONS")
}

func (s *Server) initTCPSocket(addr string) (l net.Listener, err error) {
	if s.cfg.TLSConfig == nil || s.cfg.TLSConfig.ClientAuth != tls.RequireAndVerifyClientCert {
		logrus.Warn("/!\\ DON'T BIND ON ANY IP ADDRESS WITHOUT setting -tlsverify IF YOU DON'T KNOW WHAT YOU'RE DOING /!\\")
	}
	if l, err = sockets.NewTCPSocket(addr, s.cfg.TLSConfig, s.start); err != nil {
		return nil, err
	}
	if err := allocateDaemonPort(addr); err != nil {
		return nil, err
	}
	return
}

func (s *Server) makeHTTPHandler(handler httputils.APIFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		// log the handler call
		logrus.Debugf("Calling %s %s", r.Method, r.URL.Path)

		// Define the context that we'll pass around to share info
		// like the docker-request-id.
		//
		// The 'context' will be used for global data that should
		// apply to all requests. Data that is specific to the
		// immediate function being called should still be passed
		// as 'args' on the function call.
		ctx := context.Background()
		handlerFunc := s.handleWithGlobalMiddlewares(handler)

		if err := handlerFunc(ctx, w, r, mux.Vars(r)); err != nil {
			logrus.Errorf("Handler for %s %s returned error: %s", r.Method, r.URL.Path, utils.GetErrorMessage(err))
			httputils.WriteError(w, err)
		}
	}
}

// InitRouters initializes a list of routers for the server.
// Sets those routers as Handler for each server.
func (s *Server) InitRouters(d *daemon.Daemon) {
	s.addRouter(local.NewRouter(d))
	s.addRouter(network.NewRouter(d))

	for _, srv := range s.servers {
		srv.srv.Handler = s.CreateMux()
	}
}

// addRouter adds a new router to the server.
func (s *Server) addRouter(r router.Router) {
	s.routers = append(s.routers, r)
}

// CreateMux initializes the main router the server uses.
// we keep enableCors just for legacy usage, need to be removed in the future
func (s *Server) CreateMux() *mux.Router {
	m := mux.NewRouter()
	if os.Getenv("DEBUG") != "" {
		profilerSetup(m, "/debug/")
	}

	logrus.Debugf("Registering routers")
	for _, apiRouter := range s.routers {
		for _, r := range apiRouter.Routes() {
			f := s.makeHTTPHandler(r.Handler())

			logrus.Debugf("Registering %s, %s", r.Method(), r.Path())
			m.Path(versionMatcher + r.Path()).Methods(r.Method()).Handler(f)
			m.Path(r.Path()).Methods(r.Method()).Handler(f)
		}
	}

	return m
}

// AcceptConnections allows clients to connect to the API server.
// Referenced Daemon is notified about this server, and waits for the
// daemon acknowledgement before the incoming connections are accepted.
func (s *Server) AcceptConnections() {
	// close the lock so the listeners start accepting connections
	select {
	case <-s.start:
	default:
		close(s.start)
	}
}