go.net/ipv4: simplify ancillary helpers
This CL reduces unnecessary allocations in ancillary helper
functions. Also clarifies documentation on ControlMessage,
ControlFlags.
benchmark old allocs new allocs delta
BenchmarkReadWriteNetUDP-2 6 6 0.00%
BenchmarkReadWriteIPv4UDP-2 17 15 -11.76%
R=dave
CC=golang-dev
https://golang.org/cl/9232050
diff --git a/ipv4/control.go b/ipv4/control.go
index 56d906f..6d1a49d 100644
--- a/ipv4/control.go
+++ b/ipv4/control.go
@@ -11,15 +11,13 @@
)
type rawOpt struct {
- mu sync.Mutex
+ sync.Mutex
cflags ControlFlags
}
-func (o *rawOpt) lock() { o.mu.Lock() }
-func (o *rawOpt) unlock() { o.mu.Unlock() }
-func (o *rawOpt) set(f ControlFlags) { o.cflags |= f }
-func (o *rawOpt) clear(f ControlFlags) { o.cflags &^= f }
-func (o *rawOpt) isset(f ControlFlags) bool { return o.cflags&f != 0 }
+func (c *rawOpt) set(f ControlFlags) { c.cflags |= f }
+func (c *rawOpt) clear(f ControlFlags) { c.cflags &^= f }
+func (c *rawOpt) isset(f ControlFlags) bool { return c.cflags&f != 0 }
type ControlFlags uint
@@ -27,16 +25,23 @@
FlagTTL ControlFlags = 1 << iota // pass the TTL on the received packet
FlagSrc // pass the source address on the received packet
FlagDst // pass the destination address on the received packet
- FlagInterface // pass the interface index on the received packet or outgoing packet
+ FlagInterface // pass the interface index on the received packet
)
-// A ControlMessage represents control information that contains per
-// packet IP-level option data.
+// A ControlMessage represents per packet basis IP-level socket options.
type ControlMessage struct {
- TTL int // time-to-live
- Src net.IP // source address
- Dst net.IP // destination address
- IfIndex int // interface index
+ // Receiving socket options: SetControlMessage allows to
+ // receive the options from the protocol stack using ReadFrom
+ // method of PacketConn or RawConn.
+ //
+ // Specifying socket options: ControlMessage for WriteTo
+ // method of PacketConn or RawConn allows to send the options
+ // to the protocol stack.
+ //
+ TTL int // time-to-live, receiving only
+ Src net.IP // source address, specifying only
+ Dst net.IP // destination address, receiving only
+ IfIndex int // interface index, must be 1 <= value when specifying
}
func (cm *ControlMessage) String() string {
diff --git a/ipv4/control_bsd.go b/ipv4/control_bsd.go
index cd9dc87..6b1b557 100644
--- a/ipv4/control_bsd.go
+++ b/ipv4/control_bsd.go
@@ -14,8 +14,8 @@
)
func setControlMessage(fd int, opt *rawOpt, cf ControlFlags, on bool) error {
- opt.lock()
- defer opt.unlock()
+ opt.Lock()
+ defer opt.Unlock()
if cf&FlagTTL != 0 {
if err := setIPv4ReceiveTTL(fd, on); err != nil {
return err
@@ -50,43 +50,53 @@
}
func newControlMessage(opt *rawOpt) (oob []byte) {
- opt.lock()
- defer opt.unlock()
+ opt.Lock()
+ defer opt.Unlock()
+ l, off := 0, 0
if opt.isset(FlagTTL) {
- b := make([]byte, syscall.CmsgSpace(1))
- cmsg := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
- cmsg.Level = ianaProtocolIP
- cmsg.Type = syscall.IP_RECVTTL
- cmsg.SetLen(syscall.CmsgLen(1))
- oob = append(oob, b...)
+ l += syscall.CmsgSpace(1)
}
if opt.isset(FlagDst) {
- b := make([]byte, syscall.CmsgSpace(net.IPv4len))
- cmsg := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
- cmsg.Level = ianaProtocolIP
- cmsg.Type = syscall.IP_RECVDSTADDR
- cmsg.SetLen(syscall.CmsgLen(net.IPv4len))
- oob = append(oob, b...)
+ l += syscall.CmsgSpace(net.IPv4len)
}
if opt.isset(FlagInterface) {
- b := make([]byte, syscall.CmsgSpace(syscall.SizeofSockaddrDatalink))
- cmsg := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
- cmsg.Level = ianaProtocolIP
- cmsg.Type = syscall.IP_RECVIF
- cmsg.SetLen(syscall.CmsgLen(syscall.SizeofSockaddrDatalink))
- oob = append(oob, b...)
+ l += syscall.CmsgSpace(syscall.SizeofSockaddrDatalink)
+ }
+ if l > 0 {
+ oob = make([]byte, l)
+ if opt.isset(FlagTTL) {
+ m := (*syscall.Cmsghdr)(unsafe.Pointer(&oob[off]))
+ m.Level = ianaProtocolIP
+ m.Type = syscall.IP_RECVTTL
+ m.SetLen(syscall.CmsgLen(1))
+ off += syscall.CmsgSpace(1)
+ }
+ if opt.isset(FlagDst) {
+ m := (*syscall.Cmsghdr)(unsafe.Pointer(&oob[off]))
+ m.Level = ianaProtocolIP
+ m.Type = syscall.IP_RECVDSTADDR
+ m.SetLen(syscall.CmsgLen(net.IPv4len))
+ off += syscall.CmsgSpace(net.IPv4len)
+ }
+ if opt.isset(FlagInterface) {
+ m := (*syscall.Cmsghdr)(unsafe.Pointer(&oob[off]))
+ m.Level = ianaProtocolIP
+ m.Type = syscall.IP_RECVIF
+ m.SetLen(syscall.CmsgLen(syscall.SizeofSockaddrDatalink))
+ off += syscall.CmsgSpace(syscall.SizeofSockaddrDatalink)
+ }
}
return
}
func parseControlMessage(b []byte) (*ControlMessage, error) {
+ if len(b) == 0 {
+ return nil, nil
+ }
cmsgs, err := syscall.ParseSocketControlMessage(b)
if err != nil {
return nil, os.NewSyscallError("parse socket control message", err)
}
- if len(b) == 0 {
- return nil, nil
- }
cm := &ControlMessage{}
for _, m := range cmsgs {
if m.Header.Level != ianaProtocolIP {
@@ -96,8 +106,7 @@
case syscall.IP_RECVTTL:
cm.TTL = int(*(*byte)(unsafe.Pointer(&m.Data[:1][0])))
case syscall.IP_RECVDSTADDR:
- v := m.Data[:4]
- cm.Dst = net.IPv4(v[0], v[1], v[2], v[3])
+ cm.Dst = m.Data[:net.IPv4len]
case syscall.IP_RECVIF:
sadl := (*syscall.SockaddrDatalink)(unsafe.Pointer(&m.Data[0]))
cm.IfIndex = int(sadl.Index)
diff --git a/ipv4/control_linux.go b/ipv4/control_linux.go
index cf2dcf0..fa7630f 100644
--- a/ipv4/control_linux.go
+++ b/ipv4/control_linux.go
@@ -5,7 +5,6 @@
package ipv4
import (
- "net"
"os"
"syscall"
"unsafe"
@@ -16,8 +15,8 @@
const pktinfo = FlagSrc | FlagDst | FlagInterface
func setControlMessage(fd int, opt *rawOpt, cf ControlFlags, on bool) error {
- opt.lock()
- defer opt.unlock()
+ opt.Lock()
+ defer opt.Unlock()
if cf&FlagTTL != 0 {
if err := setIPv4ReceiveTTL(fd, on); err != nil {
return err
@@ -42,35 +41,43 @@
}
func newControlMessage(opt *rawOpt) (oob []byte) {
- opt.lock()
- defer opt.unlock()
+ opt.Lock()
+ defer opt.Unlock()
+ l, off := 0, 0
if opt.isset(FlagTTL) {
- b := make([]byte, syscall.CmsgSpace(1))
- cmsg := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
- cmsg.Level = ianaProtocolIP
- cmsg.Type = syscall.IP_RECVTTL
- cmsg.SetLen(syscall.CmsgLen(1))
- oob = append(oob, b...)
+ l += syscall.CmsgSpace(1)
}
if opt.isset(pktinfo) {
- b := make([]byte, syscall.CmsgSpace(syscall.SizeofInet4Pktinfo))
- cmsg := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
- cmsg.Level = ianaProtocolIP
- cmsg.Type = syscall.IP_PKTINFO
- cmsg.SetLen(syscall.CmsgLen(syscall.SizeofInet4Pktinfo))
- oob = append(oob, b...)
+ l += syscall.CmsgSpace(syscall.SizeofInet4Pktinfo)
+ }
+ if l > 0 {
+ oob = make([]byte, l)
+ if opt.isset(FlagTTL) {
+ m := (*syscall.Cmsghdr)(unsafe.Pointer(&oob[off]))
+ m.Level = ianaProtocolIP
+ m.Type = syscall.IP_RECVTTL
+ m.SetLen(syscall.CmsgLen(1))
+ off += syscall.CmsgSpace(1)
+ }
+ if opt.isset(pktinfo) {
+ m := (*syscall.Cmsghdr)(unsafe.Pointer(&oob[off]))
+ m.Level = ianaProtocolIP
+ m.Type = syscall.IP_PKTINFO
+ m.SetLen(syscall.CmsgLen(syscall.SizeofInet4Pktinfo))
+ off += syscall.CmsgSpace(syscall.SizeofInet4Pktinfo)
+ }
}
return
}
func parseControlMessage(b []byte) (*ControlMessage, error) {
+ if len(b) == 0 {
+ return nil, nil
+ }
cmsgs, err := syscall.ParseSocketControlMessage(b)
if err != nil {
return nil, os.NewSyscallError("parse socket control message", err)
}
- if len(b) == 0 {
- return nil, nil
- }
cm := &ControlMessage{}
for _, m := range cmsgs {
if m.Header.Level != ianaProtocolIP {
@@ -82,7 +89,7 @@
case syscall.IP_PKTINFO:
pi := (*syscall.Inet4Pktinfo)(unsafe.Pointer(&m.Data[0]))
cm.IfIndex = int(pi.Ifindex)
- cm.Dst = net.IPv4(pi.Addr[0], pi.Addr[1], pi.Addr[2], pi.Addr[3])
+ cm.Dst = pi.Addr[:]
}
}
return cm, nil
@@ -92,25 +99,28 @@
if cm == nil {
return
}
- pi := &syscall.Inet4Pktinfo{}
+ l, off := 0, 0
pion := false
- if ip := cm.Src.To4(); ip != nil {
- copy(pi.Spec_dst[:], ip[:net.IPv4len])
+ if cm.Src.To4() != nil || cm.IfIndex != 0 {
pion = true
+ l += syscall.CmsgSpace(syscall.SizeofInet4Pktinfo)
}
- if cm.IfIndex != 0 {
- pi.Ifindex = int32(cm.IfIndex)
- pion = true
- }
- if pion {
- b := make([]byte, syscall.CmsgSpace(syscall.SizeofInet4Pktinfo))
- cmsg := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
- cmsg.Level = ianaProtocolIP
- cmsg.Type = syscall.IP_PKTINFO
- cmsg.SetLen(syscall.CmsgLen(syscall.SizeofInet4Pktinfo))
- data := b[syscall.CmsgLen(0):]
- copy(data[:syscall.SizeofInet4Pktinfo], (*[syscall.SizeofInet4Pktinfo]byte)(unsafe.Pointer(pi))[:syscall.SizeofInet4Pktinfo])
- oob = append(oob, b...)
+ if l > 0 {
+ oob = make([]byte, l)
+ if pion {
+ m := (*syscall.Cmsghdr)(unsafe.Pointer(&oob[off]))
+ m.Level = ianaProtocolIP
+ m.Type = syscall.IP_PKTINFO
+ m.SetLen(syscall.CmsgLen(syscall.SizeofInet4Pktinfo))
+ pi := (*syscall.Inet4Pktinfo)(unsafe.Pointer(&oob[off+syscall.CmsgLen(0)]))
+ if ip := cm.Src.To4(); ip != nil {
+ copy(pi.Addr[:], ip)
+ }
+ if cm.IfIndex != 0 {
+ pi.Ifindex = int32(cm.IfIndex)
+ }
+ off += syscall.CmsgSpace(syscall.SizeofInet4Pktinfo)
+ }
}
return
}
diff --git a/ipv4/control_plan9.go b/ipv4/control_plan9.go
index df9d50b..18feaaa 100644
--- a/ipv4/control_plan9.go
+++ b/ipv4/control_plan9.go
@@ -4,9 +4,7 @@
package ipv4
-import (
- "syscall"
-)
+import "syscall"
func setControlMessage(fd int, opt *rawOpt, cf ControlFlags, on bool) error {
// TODO(mikio): Implement this
diff --git a/ipv4/control_windows.go b/ipv4/control_windows.go
index 7b1d604..5a68a55 100644
--- a/ipv4/control_windows.go
+++ b/ipv4/control_windows.go
@@ -4,9 +4,7 @@
package ipv4
-import (
- "syscall"
-)
+import "syscall"
func setControlMessage(fd syscall.Handle, opt *rawOpt, cf ControlFlags, on bool) error {
// TODO(mikio): Implement this
