net: avoid using Windows' TransmitFile on non-server machines

Windows API's TransmitFile function is limited to two concurrent
operations on workstation and client versions of Windows. This change
modifies the net.sendFile function to perform no work in such cases
so that TransmitFile is avoided.

Fixes #73746

Change-Id: Iba70d5d2758bf986e80c78254c8e9e10b39bb368
GitHub-Last-Rev: 315ddc0cd8034f52632dc31baf35057a8bad9bcd
GitHub-Pull-Request: golang/go#73758
Reviewed-on: https://go-review.googlesource.com/c/go/+/673855
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Auto-Submit: Damien Neil <dneil@google.com>
Reviewed-by: Quim Muntal <quimmuntal@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Damien Neil <dneil@google.com>

3 files changed, 36 insertions, 7 deletions

diff --git a/src/internal/syscall/windows/types_windows.go b/src/internal/syscall/windows/types_windows.go
index 9f8f61f6d9..93664b4b7d 100644
--- a/src/internal/syscall/windows/types_windows.go
+++ b/src/internal/syscall/windows/types_windows.go
@@ -256,3 +256,7 @@ type FILE_COMPLETION_INFORMATION struct {
 	Port syscall.Handle
 	Key  uintptr
 }
+
+// https://learn.microsoft.com/en-us/windows/win32/api/winnt/ns-winnt-osversioninfoexa
+// https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/ns-wdm-_osversioninfoexw
+const VER_NT_WORKSTATION = 0x0000001
diff --git a/src/internal/syscall/windows/version_windows.go b/src/internal/syscall/windows/version_windows.go
index cb5f6ba6cd..5edf7a01e2 100644
--- a/src/internal/syscall/windows/version_windows.go
+++ b/src/internal/syscall/windows/version_windows.go
@@ -11,28 +11,53 @@ import (
 	"unsafe"
 )
 
-// https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/ns-wdm-_osversioninfow
-type _OSVERSIONINFOW struct {
+// https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/ns-wdm-_osversioninfoexw
+type _OSVERSIONINFOEXW struct {
 	osVersionInfoSize uint32
 	majorVersion      uint32
 	minorVersion      uint32
 	buildNumber       uint32
 	platformId        uint32
 	csdVersion        [128]uint16
+	servicePackMajor  uint16
+	servicePackMinor  uint16
+	suiteMask         uint16
+	productType       byte
+	reserved          byte
 }
 
 // According to documentation, RtlGetVersion function always succeeds.
-//sys	rtlGetVersion(info *_OSVERSIONINFOW) = ntdll.RtlGetVersion
+//sys	rtlGetVersion(info *_OSVERSIONINFOEXW) = ntdll.RtlGetVersion
+
+// Retrieves version information of the current Windows OS
+// from the RtlGetVersion API.
+func getVersionInfo() *_OSVERSIONINFOEXW {
+	info := _OSVERSIONINFOEXW{}
+	info.osVersionInfoSize = uint32(unsafe.Sizeof(info))
+	rtlGetVersion(&info)
+	return &info
+}
 
 // Version retrieves the major, minor, and build version numbers
 // of the current Windows OS from the RtlGetVersion API.
 func Version() (major, minor, build uint32) {
-	info := _OSVERSIONINFOW{}
-	info.osVersionInfoSize = uint32(unsafe.Sizeof(info))
-	rtlGetVersion(&info)
+	info := getVersionInfo()
 	return info.majorVersion, info.minorVersion, info.buildNumber
 }
 
+// SupportUnlimitedTransmitFile indicates whether the current
+// Windows version's TransmitFile function imposes any
+// concurrent operation limits.
+// Workstation and client versions of Windows limit the number
+// of concurrent TransmitFile operations allowed on the system
+// to a maximum of two. Please see:
+// https://learn.microsoft.com/en-us/windows/win32/api/mswsock/nf-mswsock-transmitfile
+// https://golang.org/issue/73746
+var SupportUnlimitedTransmitFile = sync.OnceValue(func() bool {
+	info := getVersionInfo()
+	return info.productType != VER_NT_WORKSTATION
+})
+
 var (
 	supportTCPKeepAliveIdle     bool
 	supportTCPKeepAliveInterval bool
diff --git a/src/internal/syscall/windows/zsyscall_windows.go b/src/internal/syscall/windows/zsyscall_windows.go
index 8dcb377c3e..90cf0b92a4 100644
--- a/src/internal/syscall/windows/zsyscall_windows.go
+++ b/src/internal/syscall/windows/zsyscall_windows.go
@@ -539,7 +539,7 @@ func NtSetInformationFile(handle syscall.Handle, iosb *IO_STATUS_BLOCK, inBuffer
 	return
 }
 
-func rtlGetVersion(info *_OSVERSIONINFOW) {
+func rtlGetVersion(info *_OSVERSIONINFOEXW) {
 	syscall.Syscall(procRtlGetVersion.Addr(), 1, uintptr(unsafe.Pointer(info)), 0, 0)
 	return
 }