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|
package nslcd_proto
import (
"encoding/binary"
"fmt"
"io"
"net"
"reflect"
"syscall"
)
type NslcdObject interface {
NslcdWrite(fd io.Writer)
}
type NslcdObjectPtr interface {
NslcdRead(fd io.Reader)
}
func write(fd io.Writer, data interface{}) {
switch data := data.(type) {
// basic data types
case NslcdObject:
data.NslcdWrite(fd)
case []byte:
_, err := fd.Write(data)
if err != nil {
panic(err)
}
case int32:
err := binary.Write(fd, binary.BigEndian, data)
if err != nil {
panic(err)
}
// composite datatypes
case string:
write(fd, int32(len(data)))
write(fd, []byte(data))
case []string:
write(fd, int32(len(data)))
for _, item := range data {
write(fd, item)
}
case net.IP:
var af int32 = -1
switch len(data) {
case net.IPv4len:
af = syscall.AF_INET
case net.IPv6len:
af = syscall.AF_INET6
}
var bytes []byte
if af < 0 {
bytes = make([]byte, 0)
} else {
bytes = data
}
write(fd, af)
write(fd, int32(len(bytes)))
write(fd, bytes)
case []net.IP:
write(fd, int32(len(data)))
for _, item := range data {
write(fd, item)
}
default:
v := reflect.ValueOf(data)
switch v.Kind() {
case reflect.Struct:
for i, n := 0, v.NumField(); i < n; i++ {
write(fd, v.Field(i).Interface())
}
default:
panic(fmt.Sprintf("Invalid structure to write NSLCD protocol data from: %T ( %#v )", data, data))
}
}
}
func read(fd io.Reader, data interface{}) {
switch data := data.(type) {
// basic data types
case NslcdObjectPtr:
data.NslcdRead(fd)
case *[]byte:
_, err := fd.Read(*data)
if err != nil {
panic(err)
}
case *int32:
err := binary.Read(fd, binary.BigEndian, data)
if err != nil {
panic(err)
}
// composite datatypes
case *string:
var len int32
read(fd, &len)
buf := make([]byte, len)
read(fd, &buf)
*data = string(buf)
case *[]string:
var num int32
read(fd, &num)
*data = make([]string, num)
for i := 0; i < int(num); i++ {
read(fd, &((*data)[i]))
}
case *net.IP:
var af int32
read(fd, &af)
var _len int32
switch af {
case syscall.AF_INET:
_len = net.IPv4len
case syscall.AF_INET6:
_len = net.IPv6len
default:
panic(NslcdError(fmt.Sprintf("incorrect address family specified: %d", af)))
}
var len int32
read(fd, &len)
if len != _len {
panic(NslcdError(fmt.Sprintf("address length incorrect: %d", len)))
}
buf := make([]byte, len)
read(fd, &buf)
*data = buf
case *[]net.IP:
var num int32
read(fd, &num)
*data = make([]net.IP, num)
for i := 0; i < int(num); i++ {
read(fd, &((*data)[i]))
}
default:
p := reflect.ValueOf(data)
v := reflect.Indirect(p)
if p == v || v.Kind() != reflect.Struct {
panic(fmt.Sprintf("The argument to nslcd_proto.read() must be a pointer: %T ( %#v )", data, data))
}
for i, n := 0, v.NumField(); i < n; i++ {
read(fd, v.Field(i).Addr().Interface())
}
}
}
|
