套接字 – Perl 6 udp套接字：如何从服务器读取响应？

UDP连接由4个东西定义,(发送方地址,发送方端口,接收方地址,接收方端口).

服务器可以侦听给定的地址/端口.收到数据包后,通常会有方法查询发件人的地址/端口.这就是我在Perl 6中看不到的东西.

客户端可以将数据包定向到特定的服务器地址/端口.客户端通常会选择一个随机的“发送端口”,给出“连接”所需的第四个元素(在这种无连接协议中).

因此,如在其他语言的示例中,客户端发送数据包,服务器查找发送方的地址/端口,然后将数据包返回到同一地址/端口.在发送其数据包之后,客户端再次侦听它发送数据包的相同随机端口,以接收来自服务器的响应.我没有在Perl 6中看到一个明显的方法,就是在刚刚发送到的同一端口上使用recv跟进打印到.

话虽如此,Perl 6有一个出色的NativeCall工具,可用于直接调用动态库,因此如果您愿意,可以通过实际系统调用完成所需的一切.

无论如何,这不是’官方’Perl 6方式,一旦IO :: Socket :: Async可以做你想做的事,就可以从脑中清除所有这些,但是这里是如何用NativeCall做的：

server-udp.pl

use NativeCall;

constant AF_INET := 2;
constant SOCK_DGRAM := 2;

class sockaddr_in is repr('CStruct')
{
    has int16 $.sin_family;
    has uint16 $.sin_port;
    has int32 $.sin_addr;
    has int64 $.pad;
}

sub socket(int32,int32,int32 --> int32) is native() {}
sub bind(int32,sockaddr_in,uint32 --> int32) is native() {}
sub htons(uint16 --> uint16) is native() {}
sub ntohs(uint16 --> uint16) is native() {}
sub inet_ntoa(int32 --> Str) is native() {}
sub perror(Str) is native() {}
sub recvfrom(int32,Blob,size_t,int32 is rw --> ssize_t) is native() {}
sub sendto(int32,int32 --> ssize_t) is native() {}

my int32 $sock = socket(AF_INET,SOCK_DGRAM,0);
perror('socket') // die if $sock < 0;

my $addr = sockaddr_in.new(sin_family => AF_INET,sin_port => htons(3333),sin_addr => 0);

my $ret = bind($sock,$addr,nativesizeof(sockaddr_in));

perror('bind') // die if $ret < 0;

my $buf = buf8.allocate(1024);

my $fromaddr = sockaddr_in.new;

my int32 $addrsize = nativesizeof(sockaddr_in);

loop
{
    $ret = recvfrom($sock,$buf,$buf.bytes,$fromaddr,$addrsize);
    perror('recvfrom') // die if $ret < 0;

    my $msg = $buf.decode;
    $msg.print;

    my $return-msg = "Thank you for saying $msg";
    my $return-buf = $return-msg.encode;

    $ret = sendto($sock,$return-buf,$return-buf.bytes,$addrsize);
    perror('sendto') // die if $ret < 0;
}

client-udp.pl

use NativeCall;

constant AF_INET := 2;
constant SOCK_DGRAM := 2;

class sockaddr_in is repr('CStruct')
{
    has int16 $.sin_family;
    has uint16 $.sin_port;
    has int32 $.sin_addr;
    has int64 $.pad;
}

sub socket(int32,int32 --> int32) is native() {}
sub htons(uint16 --> uint16) is native() {}
sub inet_ntoa(int32 --> Str) is native() {}
sub inet_aton(Str,int32 is rw --> int32) is native() {}
sub perror(Str) is native() {}
sub recvfrom(int32,int32 is rw --> ssize_t) is native() {}
sub recv(int32,int32 --> ssize_t) is native() {}
sub sendto(int32,0);
perror('socket') // die if $sock < 0;

my int32 $addr-ip;
inet_aton('127.0.0.1',$addr-ip) or die "Bad address";

my $addr = sockaddr_in.new(sin_family => AF_INET,sin_addr => $addr-ip);

my $msg = "Hello,Perl 6!n".encode;

my $ret = sendto($sock,$msg,$msg.bytes,nativesizeof(sockaddr_in));
perror('sendto') // die if $ret < 0;

my $buf = buf8.allocate(1024);

$ret = recv($sock,0);

say "Return Msg: ",$buf.decode;