1 files changed, 426 insertions, 0 deletions
diff --git a/core/core.go b/core/core.go
new file mode 100644
index 000000000..1c0eba49a
--- /dev/null
+++ b/core/core.go
@@ -0,0 +1,426 @@
+// Package caddy implements the CoreDNS web server as a service
+// in your own Go programs.
+//
+// To use this package, follow a few simple steps:
+//
+//   1. Set the AppName and AppVersion variables.
+//   2. Call LoadCorefile() to get the Corefile (it
+//      might have been piped in as part of a restart).
+//      You should pass in your own Corefile loader.
+//   3. Call caddy.Start() to start CoreDNS, caddy.Stop()
+//      to stop it, or caddy.Restart() to restart it.
+//
+// You should use caddy.Wait() to wait for all CoreDNS servers
+// to quit before your process exits.
+package core
+
+import (
+	"bytes"
+	"encoding/gob"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"path"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/miekg/coredns/core/https"
+	"github.com/miekg/coredns/server"
+)
+
+// Configurable application parameters
+var (
+	// AppName is the name of the application.
+	AppName string
+
+	// AppVersion is the version of the application.
+	AppVersion string
+
+	// Quiet when set to true, will not show any informative output on initialization.
+	Quiet bool
+
+	// PidFile is the path to the pidfile to create.
+	PidFile string
+
+	// GracefulTimeout is the maximum duration of a graceful shutdown.
+	GracefulTimeout time.Duration
+)
+
+var (
+	// corefile is the input configuration text used for this process
+	corefile Input
+
+	// corefileMu protects corefile during changes
+	corefileMu sync.Mutex
+
+	// errIncompleteRestart occurs if this process is a fork
+	// of the parent but no Corefile was piped in
+	errIncompleteRestart = errors.New("incomplete restart")
+
+	// servers is a list of all the currently-listening servers
+	servers []*server.Server
+
+	// serversMu protects the servers slice during changes
+	serversMu sync.Mutex
+
+	// wg is used to wait for all servers to shut down
+	wg sync.WaitGroup
+
+	// loadedGob is used if this is a child process as part of
+	// a graceful restart; it is used to map listeners to their
+	// index in the list of inherited file descriptors. This
+	// variable is not safe for concurrent access.
+	loadedGob corefileGob
+
+	// startedBefore should be set to true if CoreDNS has been started
+	// at least once (does not indicate whether currently running).
+	startedBefore bool
+)
+
+const (
+	// DefaultHost is the default host.
+	DefaultHost = ""
+	// DefaultPort is the default port.
+	DefaultPort = "53"
+	// DefaultRoot is the default root folder.
+	DefaultRoot = "."
+)
+
+// Start starts CoreDNS with the given Corefile. If crfile
+// is nil, the LoadCorefile function will be called to get
+// one.
+//
+// This function blocks until all the servers are listening.
+//
+// Note (POSIX): If Start is called in the child process of a
+// restart more than once within the duration of the graceful
+// cutoff (i.e. the child process called Start a first time,
+// then called Stop, then Start again within the first 5 seconds
+// or however long GracefulTimeout is) and the Corefiles have
+// at least one listener address in common, the second Start
+// may fail with "address already in use" as there's no
+// guarantee that the parent process has relinquished the
+// address before the grace period ends.
+func Start(crfile Input) (err error) {
+	// If we return with no errors, we must do two things: tell the
+	// parent that we succeeded and write to the pidfile.
+	defer func() {
+		if err == nil {
+			signalSuccessToParent() // TODO: Is doing this more than once per process a bad idea? Start could get called more than once in other apps.
+			if PidFile != "" {
+				err := writePidFile()
+				if err != nil {
+					log.Printf("[ERROR] Could not write pidfile: %v", err)
+				}
+			}
+		}
+	}()
+
+	// Input must never be nil; try to load something
+	if crfile == nil {
+		crfile, err = LoadCorefile(nil)
+		if err != nil {
+			return err
+		}
+	}
+
+	corefileMu.Lock()
+	corefile = crfile
+	corefileMu.Unlock()
+
+	// load the server configs (activates Let's Encrypt)
+	configs, err := loadConfigs(path.Base(crfile.Path()), bytes.NewReader(crfile.Body()))
+	if err != nil {
+		return err
+	}
+
+	// group zones by address
+	groupings, err := arrangeBindings(configs)
+	if err != nil {
+		return err
+	}
+
+	// Start each server with its one or more configurations
+	err = startServers(groupings)
+	if err != nil {
+		return err
+	}
+	startedBefore = true
+
+	// Show initialization output
+	if !Quiet && !IsRestart() {
+		var checkedFdLimit bool
+		for _, group := range groupings {
+			for _, conf := range group.Configs {
+				// Print address of site
+				fmt.Println(conf.Address())
+
+				// Note if non-localhost site resolves to loopback interface
+				if group.BindAddr.IP.IsLoopback() && !isLocalhost(conf.Host) {
+					fmt.Printf("Notice: %s is only accessible on this machine (%s)\n",
+						conf.Host, group.BindAddr.IP.String())
+				}
+				if !checkedFdLimit && !group.BindAddr.IP.IsLoopback() && !isLocalhost(conf.Host) {
+					checkFdlimit()
+					checkedFdLimit = true
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
+// startServers starts all the servers in groupings,
+// taking into account whether or not this process is
+// a child from a graceful restart or not. It blocks
+// until the servers are listening.
+func startServers(groupings bindingGroup) error {
+	var startupWg sync.WaitGroup
+	errChan := make(chan error, len(groupings)) // must be buffered to allow Serve functions below to return if stopped later
+
+	for _, group := range groupings {
+		s, err := server.New(group.BindAddr.String(), group.Configs, GracefulTimeout)
+		if err != nil {
+			return err
+		}
+		// TODO(miek): does not work, because this callback uses http instead of dns
+		//		s.ReqCallback = https.RequestCallback // ensures we can solve ACME challenges while running
+		if s.OnDemandTLS {
+			s.TLSConfig.GetCertificate = https.GetOrObtainCertificate // TLS on demand -- awesome!
+		} else {
+			s.TLSConfig.GetCertificate = https.GetCertificate
+		}
+
+		var (
+			ln net.Listener
+			pc net.PacketConn
+		)
+
+		if IsRestart() {
+			// Look up this server's listener in the map of inherited file descriptors; if we don't have one, we must make a new one (later).
+			if fdIndex, ok := loadedGob.ListenerFds["tcp"+s.Addr]; ok {
+				file := os.NewFile(fdIndex, "")
+
+				fln, err := net.FileListener(file)
+				if err != nil {
+					return err
+				}
+
+				ln, ok = fln.(*net.TCPListener)
+				if !ok {
+					return errors.New("listener for " + s.Addr + " was not a *net.TCPListener")
+				}
+
+				file.Close()
+				delete(loadedGob.ListenerFds, "tcp"+s.Addr)
+			}
+			if fdIndex, ok := loadedGob.ListenerFds["udp"+s.Addr]; ok {
+				file := os.NewFile(fdIndex, "")
+
+				fpc, err := net.FilePacketConn(file)
+				if err != nil {
+					return err
+				}
+
+				pc, ok = fpc.(*net.UDPConn)
+				if !ok {
+					return errors.New("packetConn for " + s.Addr + " was not a *net.PacketConn")
+				}
+
+				file.Close()
+				delete(loadedGob.ListenerFds, "udp"+s.Addr)
+			}
+		}
+
+		wg.Add(1)
+		go func(s *server.Server, ln net.Listener, pc net.PacketConn) {
+			defer wg.Done()
+
+			// run startup functions that should only execute when the original parent process is starting.
+			if !IsRestart() && !startedBefore {
+				err := s.RunFirstStartupFuncs()
+				if err != nil {
+					errChan <- err
+					return
+				}
+			}
+
+			// start the server
+			if ln != nil && pc != nil {
+				errChan <- s.Serve(ln, pc)
+			} else {
+				errChan <- s.ListenAndServe()
+			}
+		}(s, ln, pc)
+
+		startupWg.Add(1)
+		go func(s *server.Server) {
+			defer startupWg.Done()
+			s.WaitUntilStarted()
+		}(s)
+
+		serversMu.Lock()
+		servers = append(servers, s)
+		serversMu.Unlock()
+	}
+
+	// Close the remaining (unused) file descriptors to free up resources
+	if IsRestart() {
+		for key, fdIndex := range loadedGob.ListenerFds {
+			os.NewFile(fdIndex, "").Close()
+			delete(loadedGob.ListenerFds, key)
+		}
+	}
+
+	// Wait for all servers to finish starting
+	startupWg.Wait()
+
+	// Return the first error, if any
+	select {
+	case err := <-errChan:
+		// "use of closed network connection" is normal if it was a graceful shutdown
+		if err != nil && !strings.Contains(err.Error(), "use of closed network connection") {
+			return err
+		}
+	default:
+	}
+
+	return nil
+}
+
+// Stop stops all servers. It blocks until they are all stopped.
+// It does NOT execute shutdown callbacks that may have been
+// configured by middleware (they must be executed separately).
+func Stop() error {
+	https.Deactivate()
+
+	serversMu.Lock()
+	for _, s := range servers {
+		if err := s.Stop(); err != nil {
+			log.Printf("[ERROR] Stopping %s: %v", s.Addr, err)
+		}
+	}
+	servers = []*server.Server{} // don't reuse servers
+	serversMu.Unlock()
+
+	return nil
+}
+
+// Wait blocks until all servers are stopped.
+func Wait() {
+	wg.Wait()
+}
+
+// LoadCorefile loads a Corefile, prioritizing a Corefile
+// piped from stdin as part of a restart (only happens on first call
+// to LoadCorefile). If it is not a restart, this function tries
+// calling the user's loader function, and if that returns nil, then
+// this function resorts to the default configuration. Thus, if there
+// are no other errors, this function always returns at least the
+// default Corefile.
+func LoadCorefile(loader func() (Input, error)) (crfile Input, err error) {
+	// If we are a fork, finishing the restart is highest priority;
+	// piped input is required in this case.
+	if IsRestart() {
+		err := gob.NewDecoder(os.Stdin).Decode(&loadedGob)
+		if err != nil {
+			return nil, err
+		}
+		crfile = loadedGob.Corefile
+		atomic.StoreInt32(https.OnDemandIssuedCount, loadedGob.OnDemandTLSCertsIssued)
+	}
+
+	// Try user's loader
+	if crfile == nil && loader != nil {
+		crfile, err = loader()
+	}
+
+	// Otherwise revert to default
+	if crfile == nil {
+		crfile = DefaultInput()
+	}
+
+	return
+}
+
+// CorefileFromPipe loads the Corefile input from f if f is
+// not interactive input. f is assumed to be a pipe or stream,
+// such as os.Stdin. If f is not a pipe, no error is returned
+// but the Input value will be nil. An error is only returned
+// if there was an error reading the pipe, even if the length
+// of what was read is 0.
+func CorefileFromPipe(f *os.File) (Input, error) {
+	fi, err := f.Stat()
+	if err == nil && fi.Mode()&os.ModeCharDevice == 0 {
+		// Note that a non-nil error is not a problem. Windows
+		// will not create a stdin if there is no pipe, which
+		// produces an error when calling Stat(). But Unix will
+		// make one either way, which is why we also check that
+		// bitmask.
+		// BUG: Reading from stdin after this fails (e.g. for the let's encrypt email address) (OS X)
+		confBody, err := ioutil.ReadAll(f)
+		if err != nil {
+			return nil, err
+		}
+		return CorefileInput{
+			Contents: confBody,
+			Filepath: f.Name(),
+		}, nil
+	}
+
+	// not having input from the pipe is not itself an error,
+	// just means no input to return.
+	return nil, nil
+}
+
+// Corefile returns the current Corefile
+func Corefile() Input {
+	corefileMu.Lock()
+	defer corefileMu.Unlock()
+	return corefile
+}
+
+// Input represents a Corefile; its contents and file path
+// (which should include the file name at the end of the path).
+// If path does not apply (e.g. piped input) you may use
+// any understandable value. The path is mainly used for logging,
+// error messages, and debugging.
+type Input interface {
+	// Gets the Corefile contents
+	Body() []byte
+
+	// Gets the path to the origin file
+	Path() string
+
+	// IsFile returns true if the original input was a file on the file system
+	// that could be loaded again later if requested.
+	IsFile() bool
+}
+
+// TestServer returns a test server.
+// The ports can be retreived with server.LocalAddr(). The testserver itself can be stopped
+// with Stop(). It just takes a normal Corefile as input.
+func TestServer(t *testing.T, corefile string) (*server.Server, error) {
+
+	crfile := CorefileInput{Contents: []byte(corefile)}
+	configs, err := loadConfigs(path.Base(crfile.Path()), bytes.NewReader(crfile.Body()))
+	if err != nil {
+		return nil, err
+	}
+	groupings, err := arrangeBindings(configs)
+	if err != nil {
+		return nil, err
+	}
+	t.Logf("Starting %d servers", len(groupings))
+
+	group := groupings[0]
+	s, err := server.New(group.BindAddr.String(), group.Configs, time.Second)
+	return s, err
+}