sing/common/bufio/vectorised_unix.go

//go:build !windows

package bufio

import (
	"unsafe"

	"github.com/sagernet/sing/common/buf"
	M "github.com/sagernet/sing/common/metadata"

	"golang.org/x/sys/unix"
)

func (w *SyscallVectorisedWriter) WriteVectorised(buffers []*buf.Buffer) error {
	defer buf.ReleaseMulti(buffers)
	iovecList := make([]unix.Iovec, 0, len(buffers))
	for _, buffer := range buffers {
		var iovec unix.Iovec
		iovec.Base = &buffer.Bytes()[0]
		iovec.SetLen(buffer.Len())
		iovecList = append(iovecList, iovec)
	}
	var innerErr unix.Errno
	err := w.rawConn.Write(func(fd uintptr) (done bool) {
		_, _, innerErr = unix.Syscall(unix.SYS_WRITEV, fd, uintptr(unsafe.Pointer(&iovecList[0])), uintptr(len(iovecList)))
		return innerErr != unix.EAGAIN && innerErr != unix.EWOULDBLOCK
	})
	if innerErr != 0 {
		err = innerErr
	}
	return err
}

func (w *SyscallVectorisedPacketWriter) WriteVectorisedPacket(buffers []*buf.Buffer, destination M.Socksaddr) error {
	iovecList := make([]unix.Iovec, 0, len(buffers))
	for _, buffer := range buffers {
		var iovec unix.Iovec
		iovec.Base = &buffer.Bytes()[0]
		iovec.SetLen(buffer.Len())
		iovecList = append(iovecList, iovec)
	}
	name, nameLen := destination.Sockaddr()
	var msgHdr unix.Msghdr
	msgHdr.Name = (*byte)(name)
	msgHdr.Namelen = nameLen
	msgHdr.Iov = &iovecList[0]
	msgHdr.SetIovlen(len(iovecList))
	var innerErr unix.Errno
	err := w.rawConn.Write(func(fd uintptr) (done bool) {
		_, _, innerErr = unix.Syscall(unix.SYS_SENDMSG, fd, uintptr(unsafe.Pointer(&msgHdr)), 0)
		return innerErr != unix.EAGAIN && innerErr != unix.EWOULDBLOCK
	})
	if innerErr != 0 {
		err = innerErr
	}
	return err
}