diff options
Diffstat (limited to 'pkg/tcpip/link/rawfile')
| -rw-r--r-- | pkg/tcpip/link/rawfile/rawfile_unsafe.go | 61 |
1 files changed, 54 insertions, 7 deletions
diff --git a/pkg/tcpip/link/rawfile/rawfile_unsafe.go b/pkg/tcpip/link/rawfile/rawfile_unsafe.go index ba92aedbc..43fe57830 100644 --- a/pkg/tcpip/link/rawfile/rawfile_unsafe.go +++ b/pkg/tcpip/link/rawfile/rawfile_unsafe.go @@ -19,12 +19,66 @@ package rawfile import ( + "reflect" "unsafe" "golang.org/x/sys/unix" "gvisor.dev/gvisor/pkg/tcpip" ) +// SizeofIovec is the size of a unix.Iovec in bytes. +const SizeofIovec = unsafe.Sizeof(unix.Iovec{}) + +// MaxIovs is UIO_MAXIOV, the maximum number of iovecs that may be passed to a +// host system call in a single array. +const MaxIovs = 1024 + +// IovecFromBytes returns a unix.Iovec representing bs. +// +// Preconditions: len(bs) > 0. +func IovecFromBytes(bs []byte) unix.Iovec { + iov := unix.Iovec{ + Base: &bs[0], + } + iov.SetLen(len(bs)) + return iov +} + +func bytesFromIovec(iov unix.Iovec) (bs []byte) { + sh := (*reflect.SliceHeader)(unsafe.Pointer(&bs)) + sh.Data = uintptr(unsafe.Pointer(iov.Base)) + sh.Len = int(iov.Len) + sh.Cap = int(iov.Len) + return +} + +// AppendIovecFromBytes returns append(iovs, IovecFromBytes(bs)). If len(bs) == +// 0, AppendIovecFromBytes returns iovs without modification. If len(iovs) >= +// max, AppendIovecFromBytes replaces the final iovec in iovs with one that +// also includes the contents of bs. Note that this implies that +// AppendIovecFromBytes is only usable when the returned iovec slice is used as +// the source of a write. +func AppendIovecFromBytes(iovs []unix.Iovec, bs []byte, max int) []unix.Iovec { + if len(bs) == 0 { + return iovs + } + if len(iovs) < max { + return append(iovs, IovecFromBytes(bs)) + } + iovs[len(iovs)-1] = IovecFromBytes(append(bytesFromIovec(iovs[len(iovs)-1]), bs...)) + return iovs +} + +// MMsgHdr represents the mmsg_hdr structure required by recvmmsg() on linux. +type MMsgHdr struct { + Msg unix.Msghdr + Len uint32 + _ [4]byte +} + +// SizeofMMsgHdr is the size of a MMsgHdr in bytes. +const SizeofMMsgHdr = unsafe.Sizeof(MMsgHdr{}) + // GetMTU determines the MTU of a network interface device. func GetMTU(name string) (uint32, error) { fd, err := unix.Socket(unix.AF_UNIX, unix.SOCK_DGRAM, 0) @@ -137,13 +191,6 @@ func BlockingReadv(fd int, iovecs []unix.Iovec) (int, tcpip.Error) { } } -// MMsgHdr represents the mmsg_hdr structure required by recvmmsg() on linux. -type MMsgHdr struct { - Msg unix.Msghdr - Len uint32 - _ [4]byte -} - // BlockingRecvMMsg reads from a file descriptor that is set up as non-blocking // and stores the received messages in a slice of MMsgHdr structures. If no data // is available, it will block in a poll() syscall until the file descriptor |