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package bypass4netns
import (
"bytes"
"encoding/binary"
"fmt"
"net"
"syscall"
)
type sockaddr struct {
syscall.RawSockaddr
IP net.IP
Port int
Flowinfo uint32 // sin6_flowinfo
ScopeID uint32 // sin6_scope_id
}
func (sa *sockaddr) String() string {
return fmt.Sprintf("%s:%d", sa.IP, sa.Port)
}
func newSockaddr(buf []byte) (*sockaddr, error) {
sa := &sockaddr{}
reader := bytes.NewReader(buf)
// TODO: support big endian hosts
endian := binary.LittleEndian
if err := binary.Read(reader, endian, &sa.RawSockaddr); err != nil {
return nil, fmt.Errorf("cannot cast byte array to RawSocksddr: %w", err)
}
switch sa.Family {
case syscall.AF_INET:
addr4 := syscall.RawSockaddrInet4{}
if _, err := reader.Seek(0, 0); err != nil {
return nil, err
}
if err := binary.Read(reader, endian, &addr4); err != nil {
return nil, fmt.Errorf("cannot cast byte array to RawSockaddrInet4: %w", err)
}
sa.IP = make(net.IP, len(addr4.Addr))
copy(sa.IP, addr4.Addr[:])
p := make([]byte, 2)
binary.BigEndian.PutUint16(p, addr4.Port)
sa.Port = int(endian.Uint16(p))
case syscall.AF_INET6:
addr6 := syscall.RawSockaddrInet6{}
if _, err := reader.Seek(0, 0); err != nil {
return nil, err
}
if err := binary.Read(reader, endian, &addr6); err != nil {
return nil, fmt.Errorf("cannot cast byte array to RawSockaddrInet6: %w", err)
}
sa.IP = make(net.IP, len(addr6.Addr))
copy(sa.IP, addr6.Addr[:])
p := make([]byte, 2)
binary.BigEndian.PutUint16(p, addr6.Port)
sa.Port = int(endian.Uint16(p))
sa.Flowinfo = addr6.Flowinfo
sa.ScopeID = addr6.Scope_id
default:
return nil, fmt.Errorf("expected AF_INET or AF_INET6, got %d", sa.Family)
}
return sa, nil
}
func (sa *sockaddr) toBytes() ([]byte, error) {
res := bytes.Buffer{}
// TODO: support big endian hosts
endian := binary.LittleEndian
// ntohs
p := make([]byte, 2)
binary.BigEndian.PutUint16(p, uint16(sa.Port))
switch sa.Family {
case syscall.AF_INET:
addr4 := syscall.RawSockaddrInet4{}
addr4.Family = syscall.AF_INET
copy(addr4.Addr[:], sa.IP.To4()[:])
addr4.Port = endian.Uint16(p)
err := binary.Write(&res, endian, addr4)
if err != nil {
return nil, err
}
case syscall.AF_INET6:
addr6 := syscall.RawSockaddrInet6{}
addr6.Family = syscall.AF_INET6
copy(addr6.Addr[:], sa.IP.To16()[:])
addr6.Port = endian.Uint16(p)
addr6.Flowinfo = sa.Flowinfo
addr6.Scope_id = sa.ScopeID
err := binary.Write(&res, endian, addr6)
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("expected AF_INET or AF_INET6, got %d", sa.Family)
}
return res.Bytes(), nil
}
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