// Copyright 2009 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package net

import (
	"net";
	"os";
	"syscall";
	"unsafe";
)

func v4ToSockaddr(p IP, port int) (sa1 *syscall.Sockaddr, err os.Error) {
	p = p.To4();
	if p == nil || port < 0 || port > 0xFFFF {
		return nil, os.EINVAL
	}
	sa := new(syscall.SockaddrInet4);
	sa.Len = syscall.SizeofSockaddrInet4;
	sa.Family = syscall.AF_INET;
	sa.Port[0] = byte(port>>8);
	sa.Port[1] = byte(port);
	for i := 0; i < IPv4len; i++ {
		sa.Addr[i] = p[i]
	}
	return (*syscall.Sockaddr)(unsafe.Pointer(sa)), nil
}

func v6ToSockaddr(p IP, port int) (sa1 *syscall.Sockaddr, err os.Error) {
	p = p.To16();
	if p == nil || port < 0 || port > 0xFFFF {
		return nil, os.EINVAL
	}
	sa := new(syscall.SockaddrInet6);
	sa.Len = syscall.SizeofSockaddrInet6;
	sa.Family = syscall.AF_INET6;
	sa.Port[0] = byte(port>>8);
	sa.Port[1] = byte(port);
	for i := 0; i < IPv6len; i++ {
		sa.Addr[i] = p[i]
	}
	return (*syscall.Sockaddr)(unsafe.Pointer(sa)), nil
}

func sockaddrToIP(sa1 *syscall.Sockaddr) (p IP, port int, err os.Error) {
	switch sa1.Family {
	case syscall.AF_INET:
		sa := (*syscall.SockaddrInet4)(unsafe.Pointer(sa1));
		a := IP(&sa.Addr).To16();
		if a == nil {
			return nil, 0, os.EINVAL
		}
		return a, int(sa.Port[0])<<8 + int(sa.Port[1]), nil;
	case syscall.AF_INET6:
		sa := (*syscall.SockaddrInet6)(unsafe.Pointer(sa1));
		a := IP(&sa.Addr).To16();
		if a == nil {
			return nil, 0, os.EINVAL
		}
		return nil, int(sa.Port[0])<<8 + int(sa.Port[1]), nil;
	default:
		return nil, 0, os.EINVAL
	}
	return nil, 0, nil	// not reached
}

func listenBacklog() int64 {
	return syscall.SOMAXCONN
}

func unixToSockaddr(name string) (sa1 *syscall.Sockaddr, err os.Error) {
	sa := new(syscall.SockaddrUnix);
	n := len(name);
	if n >= len(sa.Path) || n == 0 {
		return nil, os.EINVAL;
	}
	sa.Len = byte(3 + n);	// 2 for Family, Len; 1 for NUL
	sa.Family = syscall.AF_UNIX;
	for i := 0; i < len(name); i++ {
		sa.Path[i] = name[i];
	}
	return (*syscall.Sockaddr)(unsafe.Pointer(sa)), nil;
}

func sockaddrToUnix(sa1 *syscall.Sockaddr) (string, os.Error) {
	if sa1.Family != syscall.AF_UNIX || sa1.Len < 3 || sa1.Len > syscall.SizeofSockaddrUnix {
		return "", os.EINVAL;
	}
	sa := (*syscall.SockaddrUnix)(unsafe.Pointer(sa1));
	n := int(sa.Len) - 3;	// subtract leading Family, Len, terminating NUL
	for i := 0; i < n; i++ {
		if sa.Path[i] == 0 {
			// found early NUL; assume Len is overestimating
			n = i;
			break;
		}
	}
	return string(sa.Path[0:n]), nil;
}