unix: add support for TCP_CONNECTION_INFO on macOS

x/sys provides support for accessing TCP_INFO on Linux but does
not provide support for accessing the equivalent (TCP_CONNECTION_INFO)
on macOS. This patch adds that functionality.

Fixes golang/go#53330

Change-Id: Ia1c1bf79a8bbb76f3ccfe58c61e1a82e08735152
Reviewed-on: https://go-review.googlesource.com/c/sys/+/411734
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

unix/syscall_darwin.go

@@ -393,6 +393,13 @@ func GetsockoptXucred(fd, level, opt int) (*Xucred, error) {
 	return x, err
 }
 
+func GetsockoptTCPConnectionInfo(fd, level, opt int) (*TCPConnectionInfo, error) {
+	var value TCPConnectionInfo
+	vallen := _Socklen(SizeofTCPConnectionInfo)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
 func SysctlKinfoProc(name string, args ...int) (*KinfoProc, error) {
 	mib, err := sysctlmib(name, args...)
 	if err != nil {

unix/types_darwin.go

@@ -200,6 +200,8 @@ type IPv6MTUInfo C.struct_ip6_mtuinfo
 
 type ICMPv6Filter C.struct_icmp6_filter
 
+type TCPConnectionInfo C.struct_tcp_connection_info
+
 const (
 	SizeofSockaddrInet4     = C.sizeof_struct_sockaddr_in
 	SizeofSockaddrInet6     = C.sizeof_struct_sockaddr_in6
@@ -224,6 +226,7 @@ const (
 	SizeofInet6Pktinfo      = C.sizeof_struct_in6_pktinfo
 	SizeofIPv6MTUInfo       = C.sizeof_struct_ip6_mtuinfo
 	SizeofICMPv6Filter      = C.sizeof_struct_icmp6_filter
+	SizeofTCPConnectionInfo = C.sizeof_struct_tcp_connection_info
 )
 
 // Ptrace requests

unix/ztypes_darwin_amd64.go

@@ -366,6 +366,32 @@ type ICMPv6Filter struct {
 	Filt [8]uint32
 }
 
+type TCPConnectionInfo struct {
+	State               uint8
+	Snd_wscale          uint8
+	Rcv_wscale          uint8
+	_                   uint8
+	Options             uint32
+	Flags               uint32
+	Rto                 uint32
+	Maxseg              uint32
+	Snd_ssthresh        uint32
+	Snd_cwnd            uint32
+	Snd_wnd             uint32
+	Snd_sbbytes         uint32
+	Rcv_wnd             uint32
+	Rttcur              uint32
+	Srtt                uint32
+	Rttvar              uint32
+	Txpackets           uint64
+	Txbytes             uint64
+	Txretransmitbytes   uint64
+	Rxpackets           uint64
+	Rxbytes             uint64
+	Rxoutoforderbytes   uint64
+	Txretransmitpackets uint64
+}
+
 const (
 	SizeofSockaddrInet4     = 0x10
 	SizeofSockaddrInet6     = 0x1c
@@ -390,6 +416,7 @@ const (
 	SizeofInet6Pktinfo      = 0x14
 	SizeofIPv6MTUInfo       = 0x20
 	SizeofICMPv6Filter      = 0x20
+	SizeofTCPConnectionInfo = 0x70
 )
 
 const (

unix/ztypes_darwin_arm64.go

@@ -366,6 +366,32 @@ type ICMPv6Filter struct {
 	Filt [8]uint32
 }
 
+type TCPConnectionInfo struct {
+	State               uint8
+	Snd_wscale          uint8
+	Rcv_wscale          uint8
+	_                   uint8
+	Options             uint32
+	Flags               uint32
+	Rto                 uint32
+	Maxseg              uint32
+	Snd_ssthresh        uint32
+	Snd_cwnd            uint32
+	Snd_wnd             uint32
+	Snd_sbbytes         uint32
+	Rcv_wnd             uint32
+	Rttcur              uint32
+	Srtt                uint32
+	Rttvar              uint32
+	Txpackets           uint64
+	Txbytes             uint64
+	Txretransmitbytes   uint64
+	Rxpackets           uint64
+	Rxbytes             uint64
+	Rxoutoforderbytes   uint64
+	Txretransmitpackets uint64
+}
+
 const (
 	SizeofSockaddrInet4     = 0x10
 	SizeofSockaddrInet6     = 0x1c
@@ -390,6 +416,7 @@ const (
 	SizeofInet6Pktinfo      = 0x14
 	SizeofIPv6MTUInfo       = 0x20
 	SizeofICMPv6Filter      = 0x20
+	SizeofTCPConnectionInfo = 0x70
 )
 
 const (