net/internal/socktest: new package

Package socktest provides utilities for socket testing.

This package allows test cases in the net package to simulate
complicated network conditions such as that a destination address is
resolvable/discoverable but is not routable/reachable at network layer.
Those conditions are required for testing functionality of timeout,
multiple address families.

Change-Id: Idbe32bcc3319b41b0cecac3d058014a93e13288b
Reviewed-on: https://go-review.googlesource.com/6090
Reviewed-by: Ian Lance Taylor <[email protected]>

src/net/internal/socktest/main_test.go

@@ -0,0 +1,40 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !plan9
+
+package socktest_test
+
+import (
+	"net/internal/socktest"
+	"os"
+	"syscall"
+	"testing"
+)
+
+var sw socktest.Switch
+
+func TestMain(m *testing.M) {
+	installTestHooks()
+
+	st := m.Run()
+
+	for s := range sw.Sockets() {
+		closeFunc(s)
+	}
+	uninstallTestHooks()
+	os.Exit(st)
+}
+
+func TestSocket(t *testing.T) {
+	for _, f := range []socktest.Filter{
+		func(st *socktest.Status) (socktest.AfterFilter, error) { return nil, nil },
+		nil,
+	} {
+		sw.Set(socktest.FilterSocket, f)
+		for _, family := range []int{syscall.AF_INET, syscall.AF_INET6} {
+			socketFunc(family, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
+		}
+	}
+}

src/net/internal/socktest/main_unix_test.go

@@ -0,0 +1,24 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !plan9,!windows
+
+package socktest_test
+
+import "syscall"
+
+var (
+	socketFunc func(int, int, int) (int, error)
+	closeFunc  func(int) error
+)
+
+func installTestHooks() {
+	socketFunc = sw.Socket
+	closeFunc = sw.Close
+}
+
+func uninstallTestHooks() {
+	socketFunc = syscall.Socket
+	closeFunc = syscall.Close
+}

src/net/internal/socktest/main_windows_test.go

@@ -0,0 +1,22 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package socktest_test
+
+import "syscall"
+
+var (
+	socketFunc func(int, int, int) (syscall.Handle, error)
+	closeFunc  func(syscall.Handle) error
+)
+
+func installTestHooks() {
+	socketFunc = sw.Socket
+	closeFunc = sw.Closesocket
+}
+
+func uninstallTestHooks() {
+	socketFunc = syscall.Socket
+	closeFunc = syscall.Closesocket
+}

src/net/internal/socktest/switch.go

@@ -0,0 +1,150 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package socktest provides utilities for socket testing.
+package socktest
+
+import "sync"
+
+func switchInit(sw *Switch) {
+	sw.fltab = make(map[FilterType]Filter)
+	sw.sotab = make(Sockets)
+	sw.stats = make(stats)
+}
+
+// A Switch represents a callpath point switch for socket system
+// calls.
+type Switch struct {
+	once sync.Once
+
+	fmu   sync.RWMutex
+	fltab map[FilterType]Filter
+
+	smu   sync.RWMutex
+	sotab Sockets
+	stats stats
+}
+
+// Stats returns a list of per-cookie socket statistics.
+func (sw *Switch) Stats() []Stat {
+	var st []Stat
+	sw.smu.RLock()
+	for _, s := range sw.stats {
+		ns := *s
+		st = append(st, ns)
+	}
+	sw.smu.RUnlock()
+	return st
+}
+
+// Sockets returns mappings of socket descriptor to socket status.
+func (sw *Switch) Sockets() Sockets {
+	sw.smu.RLock()
+	tab := make(Sockets, len(sw.sotab))
+	for i, s := range sw.sotab {
+		tab[i] = s
+	}
+	sw.smu.RUnlock()
+	return tab
+}
+
+// A Cookie represents a 3-tuple of a socket; address family, socket
+// type and protocol number.
+type Cookie uint64
+
+// Family returns an address family.
+func (c Cookie) Family() int { return int(c >> 48) }
+
+// Type returns a socket type.
+func (c Cookie) Type() int { return int(c << 16 >> 32) }
+
+// Protocol returns a protocol number.
+func (c Cookie) Protocol() int { return int(c & 0xff) }
+
+func cookie(family, sotype, proto int) Cookie {
+	return Cookie(family)<<48 | Cookie(sotype)&0xffffffff<<16 | Cookie(proto)&0xff
+}
+
+// A Status represents the status of a socket.
+type Status struct {
+	Cookie    Cookie
+	Err       error // error status of socket system call
+	SocketErr int   // error status of socket by SO_ERROR
+}
+
+// A Stat represents a per-cookie socket statistics.
+type Stat struct {
+	Family   int // address family
+	Type     int // socket type
+	Protocol int // protocol number
+
+	Opened    uint64 // number of sockets opened
+	Accepted  uint64 // number of sockets accepted
+	Connected uint64 // number of sockets connected
+	Closed    uint64 // number of sockets closed
+}
+
+type stats map[Cookie]*Stat
+
+func (st stats) getLocked(c Cookie) *Stat {
+	s, ok := st[c]
+	if !ok {
+		s = &Stat{Family: c.Family(), Type: c.Type(), Protocol: c.Protocol()}
+		st[c] = s
+	}
+	return s
+}
+
+// A FilterType represents a filter type.
+type FilterType int
+
+const (
+	FilterSocket        FilterType = iota // for Socket
+	FilterAccept                          // for Accept or Accept4
+	FilterConnect                         // for Connect or ConnectEx
+	FilterGetsockoptInt                   // for GetsockoptInt
+	FilterClose                           // for Close or Closesocket
+)
+
+// A Filter represents a socket system call filter.
+//
+// It will only be executed before a system call for a socket that has
+// an entry in internal table.
+// If the filter returns a non-nil error, the execution of system call
+// will be canceled and the system call function returns the non-nil
+// error.
+// It can return a non-nil AfterFilter for filtering after the
+// execution of the system call.
+type Filter func(*Status) (AfterFilter, error)
+
+func (f Filter) apply(st *Status) (AfterFilter, error) {
+	if f == nil {
+		return nil, nil
+	}
+	return f(st)
+}
+
+// An AfterFilter represents a socket system call filter after an
+// execution of a system call.
+//
+// It will only be executed after a system call for a socket that has
+// an entry in internal table.
+// If the filter returns a non-nil error, the system call function
+// returns the non-nil error.
+type AfterFilter func(*Status) error
+
+func (f AfterFilter) apply(st *Status) error {
+	if f == nil {
+		return nil
+	}
+	return f(st)
+}
+
+// Set deploys the socket system call filter f for the filter type t.
+func (sw *Switch) Set(t FilterType, f Filter) {
+	sw.once.Do(func() { switchInit(sw) })
+	sw.fmu.Lock()
+	sw.fltab[t] = f
+	sw.fmu.Unlock()
+}

src/net/internal/socktest/switch_stub.go

@@ -0,0 +1,10 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build plan9
+
+package socktest
+
+// Sockets maps a socket descriptor to the status of socket.
+type Sockets map[int]Status

src/net/internal/socktest/switch_unix.go

@@ -0,0 +1,29 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+
+package socktest
+
+// Sockets maps a socket descriptor to the status of socket.
+type Sockets map[int]Status
+
+func (sw *Switch) sockso(s int) *Status {
+	sw.smu.RLock()
+	defer sw.smu.RUnlock()
+	so, ok := sw.sotab[s]
+	if !ok {
+		return nil
+	}
+	return &so
+}
+
+// addLocked returns a new Status without locking.
+// sw.smu must be held before call.
+func (sw *Switch) addLocked(s, family, sotype, proto int) *Status {
+	sw.once.Do(func() { switchInit(sw) })
+	so := Status{Cookie: cookie(family, sotype, proto)}
+	sw.sotab[s] = so
+	return &so
+}

src/net/internal/socktest/switch_windows.go

@@ -0,0 +1,29 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package socktest
+
+import "syscall"
+
+// Sockets maps a socket descriptor to the status of socket.
+type Sockets map[syscall.Handle]Status
+
+func (sw *Switch) sockso(s syscall.Handle) *Status {
+	sw.smu.RLock()
+	defer sw.smu.RUnlock()
+	so, ok := sw.sotab[s]
+	if !ok {
+		return nil
+	}
+	return &so
+}
+
+// addLocked returns a new Status without locking.
+// sw.smu must be held before call.
+func (sw *Switch) addLocked(s syscall.Handle, family, sotype, proto int) *Status {
+	sw.once.Do(func() { switchInit(sw) })
+	so := Status{Cookie: cookie(family, sotype, proto)}
+	sw.sotab[s] = so
+	return &so
+}

src/net/internal/socktest/sys_cloexec.go

@@ -0,0 +1,41 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build freebsd linux
+
+package socktest
+
+import "syscall"
+
+// Accept4 wraps syscall.Accept4.
+func (sw *Switch) Accept4(s, flags int) (ns int, sa syscall.Sockaddr, err error) {
+	so := sw.sockso(s)
+	if so == nil {
+		return syscall.Accept4(s, flags)
+	}
+	sw.fmu.RLock()
+	f, _ := sw.fltab[FilterAccept]
+	sw.fmu.RUnlock()
+
+	af, err := f.apply(so)
+	if err != nil {
+		return -1, nil, err
+	}
+	ns, sa, so.Err = syscall.Accept4(s, flags)
+	if err = af.apply(so); err != nil {
+		if so.Err == nil {
+			syscall.Close(ns)
+		}
+		return -1, nil, err
+	}
+
+	if so.Err != nil {
+		return -1, nil, so.Err
+	}
+	sw.smu.Lock()
+	nso := sw.addLocked(ns, so.Cookie.Family(), so.Cookie.Type(), so.Cookie.Protocol())
+	sw.stats.getLocked(nso.Cookie).Accepted++
+	sw.smu.Unlock()
+	return ns, sa, nil
+}