/
s_posix.go
169 lines (151 loc) · 3.23 KB
/
s_posix.go
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package main
import (
_ "unsafe"
"net/netip"
"os"
"runtime"
"sync"
"syscall"
"golang.org/x/sys/unix"
)
//go:linkname RecvmsgInet4 syscall.recvmsgInet4
//go:noescape
func RecvmsgInet4(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet4) (n, oobn int, recvflags int, err error)
//go:linkname SendtoInet4 syscall.sendtoInet4
//go:noescape
func SendtoInet4(fd int, p []byte, flags int, to *syscall.SockaddrInet4) (err error)
var (
lmu sync.Mutex
laddr unix.SockaddrInet4
raddr syscall.SockaddrInet4
buf [1024]byte
)
func logUint64(f *os.File, x uint64) {
b := make([]byte, 20)
n := 0
for {
b[n] = '0' + byte(x%10)
n++
x /= 10
if x == 0 {
break
}
}
for i, j := 0, n-1; i < j; i, j = i+1, j-1 {
b[i], b[j] = b[j], b[i]
}
f.Write(b[:n])
}
func logBytes(f *os.File, x []byte) {
f.Write(x)
}
func logString(f *os.File, x string) {
f.Write([]byte(x))
}
func logLn(f *os.File) {
f.Write([]byte{'\n'})
}
func logError(f *os.File, label string, err error) {
lmu.Lock()
defer lmu.Unlock()
logString(f, label)
logString(f, ": ")
logString(f, err.Error())
logLn(f)
}
func logMsg(f *os.File, buf []byte, n int, oob []byte, oobn int, flags int, peer *syscall.SockaddrInet4) {
lmu.Lock()
defer lmu.Unlock()
logString(f, "n: ")
logUint64(f, uint64(n))
logLn(f)
logString(f, "oobn: ")
logUint64(f, uint64(oobn))
logLn(f)
logString(f, "flags: ")
logUint64(f, uint64(flags))
logLn(f)
logString(f, "peer: ")
logUint64(f, uint64(peer.Addr[0]))
logString(f, ".")
logUint64(f, uint64(peer.Addr[1]))
logString(f, ".")
logUint64(f, uint64(peer.Addr[2]))
logString(f, ".")
logUint64(f, uint64(peer.Addr[3]))
logString(f, ":")
logUint64(f, uint64(peer.Port))
logLn(f)
logString(f, "buf: ")
logBytes(f, buf[:n])
logLn(f)
logLn(f)
}
func logMemStats(f *os.File) {
var m runtime.MemStats
runtime.ReadMemStats(&m)
lmu.Lock()
defer lmu.Unlock()
logString(f, "TotalAlloc: ")
logUint64(f, uint64(m.TotalAlloc))
logLn(f)
logString(f, "Mallocs: ")
logUint64(f, uint64(m.Mallocs))
logLn(f)
logString(f, "Frees: ")
logUint64(f, uint64(m.Frees))
logLn(f)
logString(f, "NumGC: ")
logUint64(f, uint64(m.NumGC))
logLn(f)
logLn(f)
}
func sleep(sec int64) {
var tv unix.Timeval
tv.Sec = sec
unix.Select(0, nil, nil, nil, &tv)
}
func monitor() {
for {
sleep(3)
logMemStats(os.Stderr)
}
}
func main() {
go monitor()
ap, err := netip.ParseAddrPort(os.Args[1])
if err != nil {
logError(os.Stderr, "unexpected local address: ", err)
os.Exit(1)
}
fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
if err != nil {
logError(os.Stderr, "socket creation failed: ", err)
os.Exit(1)
}
defer unix.Close(fd)
laddr = unix.SockaddrInet4{
Port: int(ap.Port()),
}
err = unix.Bind(fd, &laddr)
if err != nil {
logError(os.Stderr, "bind failed: ", err)
os.Exit(1)
}
for {
n, oobn, flags, err := RecvmsgInet4(fd, buf[:], nil, 0, &raddr)
if err != nil {
logError(os.Stderr, "recv failed: ", err)
continue
}
// time.Sleep(1 * time.Millisecond)
_, _ = oobn, flags
// logMsg(os.Stdout, buf[:], n, nil, oobn, flags, &raddr)
err = SendtoInet4(fd, buf[:n], 0, &raddr)
if err != nil {
logError(os.Stderr, "send failed: ", err)
continue
}
}
}
// GODEBUG='allocfreetrace=1' ./s_posix 0.0.0.0:10123