TUN-3403: Unit test for origin/proxy to test serving HTTP and Websocket

vendor/github.com/gobwas/pool/pbytes/pool_sanitize.go

@@ -0,0 +1,121 @@
+// +build pool_sanitize
+
+package pbytes
+
+import (
+	"reflect"
+	"runtime"
+	"sync/atomic"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+const magic = uint64(0x777742)
+
+type guard struct {
+	magic  uint64
+	size   int
+	owners int32
+}
+
+const guardSize = int(unsafe.Sizeof(guard{}))
+
+type Pool struct {
+	min, max int
+}
+
+func New(min, max int) *Pool {
+	return &Pool{min, max}
+}
+
+// Get returns probably reused slice of bytes with at least capacity of c and
+// exactly len of n.
+func (p *Pool) Get(n, c int) []byte {
+	if n > c {
+		panic("requested length is greater than capacity")
+	}
+
+	pageSize := syscall.Getpagesize()
+	pages := (c+guardSize)/pageSize + 1
+	size := pages * pageSize
+
+	bts := alloc(size)
+
+	g := (*guard)(unsafe.Pointer(&bts[0]))
+	*g = guard{
+		magic:  magic,
+		size:   size,
+		owners: 1,
+	}
+
+	return bts[guardSize : guardSize+n]
+}
+
+func (p *Pool) GetCap(c int) []byte { return p.Get(0, c) }
+func (p *Pool) GetLen(n int) []byte { return Get(n, n) }
+
+// Put returns given slice to reuse pool.
+func (p *Pool) Put(bts []byte) {
+	hdr := *(*reflect.SliceHeader)(unsafe.Pointer(&bts))
+	ptr := hdr.Data - uintptr(guardSize)
+
+	g := (*guard)(unsafe.Pointer(ptr))
+	if g.magic != magic {
+		panic("unknown slice returned to the pool")
+	}
+	if n := atomic.AddInt32(&g.owners, -1); n < 0 {
+		panic("multiple Put() detected")
+	}
+
+	// Disable read and write on bytes memory pages. This will cause panic on
+	// incorrect access to returned slice.
+	mprotect(ptr, false, false, g.size)
+
+	runtime.SetFinalizer(&bts, func(b *[]byte) {
+		mprotect(ptr, true, true, g.size)
+		free(*(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
+			Data: ptr,
+			Len:  g.size,
+			Cap:  g.size,
+		})))
+	})
+}
+
+func alloc(n int) []byte {
+	b, err := unix.Mmap(-1, 0, n, unix.PROT_READ|unix.PROT_WRITE|unix.PROT_EXEC, unix.MAP_SHARED|unix.MAP_ANONYMOUS)
+	if err != nil {
+		panic(err.Error())
+	}
+	return b
+}
+
+func free(b []byte) {
+	if err := unix.Munmap(b); err != nil {
+		panic(err.Error())
+	}
+}
+
+func mprotect(ptr uintptr, r, w bool, size int) {
+	// Need to avoid "EINVAL addr is not a valid pointer,
+	// or not a multiple of PAGESIZE."
+	start := ptr & ^(uintptr(syscall.Getpagesize() - 1))
+
+	prot := uintptr(syscall.PROT_EXEC)
+	switch {
+	case r && w:
+		prot |= syscall.PROT_READ | syscall.PROT_WRITE
+	case r:
+		prot |= syscall.PROT_READ
+	case w:
+		prot |= syscall.PROT_WRITE
+	}
+
+	_, _, err := syscall.Syscall(syscall.SYS_MPROTECT,
+		start, uintptr(size), prot,
+	)
+	if err != 0 {
+		panic(err.Error())
+	}
+}