github.com/pawelgaczynski/giouring@v0.0.0-20230826085535-69588b89acb9/recvmsg.go (about)

     1  // MIT License
     2  //
     3  // Copyright (c) 2023 Paweł Gaczyński
     4  //
     5  // Permission is hereby granted, free of charge, to any person obtaining a
     6  // copy of this software and associated documentation files (the
     7  // "Software"), to deal in the Software without restriction, including
     8  // without limitation the rights to use, copy, modify, merge, publish,
     9  // distribute, sublicense, and/or sell copies of the Software, and to
    10  // permit persons to whom the Software is furnished to do so, subject to
    11  // the following conditions:
    12  //
    13  // The above copyright notice and this permission notice shall be included
    14  // in all copies or substantial portions of the Software.
    15  //
    16  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
    17  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    18  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    19  // IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
    20  // CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
    21  // TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    22  // SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    23  
    24  package giouring
    25  
    26  import (
    27  	"syscall"
    28  	"unsafe"
    29  )
    30  
    31  // liburing: CMSG_ALIGN
    32  func cmsgAlign(length uint64) uint64 {
    33  	return (length + uint64(unsafe.Sizeof(uintptr(0))) - 1) & ^(uint64(unsafe.Sizeof(uintptr(0))) - 1)
    34  }
    35  
    36  // liburing: io_uring_recvmsg_cmsg_nexthdr - https://manpages.debian.org/unstable/liburing-dev/io_uring_recvmsg_cmsg_nexthdr.3.en.html
    37  func (o *RecvmsgOut) CmsgNexthdr(msgh *syscall.Msghdr, cmsg *syscall.Cmsghdr) *syscall.Cmsghdr {
    38  	if cmsg.Len < syscall.SizeofCmsghdr {
    39  		return nil
    40  	}
    41  	end := (*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(o.CmsgFirsthdr(msgh))) + uintptr(o.ControlLen)))
    42  	cmsg = (*syscall.Cmsghdr)(unsafe.Pointer(uintptr(unsafe.Pointer(cmsg)) + uintptr(cmsgAlign(cmsg.Len))))
    43  	if uintptr(unsafe.Pointer(cmsg))+unsafe.Sizeof(*cmsg) > uintptr(unsafe.Pointer(end)) {
    44  		return nil
    45  	}
    46  	if uintptr(unsafe.Pointer(cmsg))+uintptr(cmsgAlign(cmsg.Len)) > uintptr(unsafe.Pointer(end)) {
    47  		return nil
    48  	}
    49  
    50  	return cmsg
    51  }
    52  
    53  // liburing: io_uring_recvmsg_name - https://manpages.debian.org/unstable/liburing-dev/io_uring_recvmsg_name.3.en.html
    54  func (o *RecvmsgOut) Name() unsafe.Pointer {
    55  	return unsafe.Pointer(uintptr(unsafe.Pointer(o)) + unsafe.Sizeof(*o))
    56  }
    57  
    58  // liburing: io_uring_recvmsg_cmsg_firsthdr - https://manpages.debian.org/unstable/liburing-dev/io_uring_recvmsg_cmsg_firsthdr.3.en.html
    59  func (o *RecvmsgOut) CmsgFirsthdr(msgh *syscall.Msghdr) *syscall.Cmsghdr {
    60  	if o.ControlLen < syscall.SizeofCmsghdr {
    61  		return nil
    62  	}
    63  
    64  	return (*syscall.Cmsghdr)(unsafe.Pointer(uintptr(o.Name()) + uintptr(msgh.Namelen)))
    65  }
    66  
    67  // liburing: io_uring_recvmsg_payload - https://manpages.debian.org/unstable/liburing-dev/io_uring_recvmsg_payload.3.en.html
    68  func (o *RecvmsgOut) Payload(msgh *syscall.Msghdr) unsafe.Pointer {
    69  	return unsafe.Pointer(uintptr(unsafe.Pointer(o)) +
    70  		unsafe.Sizeof(*o) +
    71  		uintptr(msgh.Namelen) +
    72  		uintptr(msgh.Controllen))
    73  }
    74  
    75  // liburing: io_uring_recvmsg_payload_length - https://manpages.debian.org/unstable/liburing-dev/io_uring_recvmsg_payload_length.3.en.html
    76  func (o *RecvmsgOut) PayloadLength(bufLen int, msgh *syscall.Msghdr) uint32 {
    77  	payloadStart := uintptr(o.Payload(msgh))
    78  	payloadEnd := uintptr(unsafe.Pointer(o)) + uintptr(bufLen)
    79  
    80  	return uint32(payloadEnd - payloadStart)
    81  }
    82  
    83  // liburing: io_uring_recvmsg_validate - https://manpages.debian.org/unstable/liburing-dev/io_uring_recvmsg_validate.3.en.html
    84  func RecvmsgValidate(buf unsafe.Pointer, bufLen int, msgh *syscall.Msghdr) *RecvmsgOut {
    85  	header := uintptr(msgh.Controllen) + uintptr(msgh.Namelen) + unsafe.Sizeof(RecvmsgOut{})
    86  	if bufLen < 0 || uintptr(bufLen) < header {
    87  		return nil
    88  	}
    89  
    90  	return (*RecvmsgOut)(buf)
    91  }