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Perl 的 udp socket 及取得來源IP 無次要群組 列印 推薦
作者或來源 瘦河馬 2009-11-18 17:26:51
關鍵字 1udp 2socket 3peeraddr
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Perl 的 udp socket 及取得來源IP

要用Perl寫一個udp的Socket是很簡單的,只消簡單的一行就可以:

my $server = IO::Socket::INET->new(LocalPort => 514, Proto => "udp") or print "Couldn't be a udp server on port $port : $@\n";

而要取得收到的 udp 封包也是容易的事,下面這裡的 $datagram 就是收到的資料,因為 udp一次最大是1024個byte,所以拿1024個就可以了。

while ($server->recv($datagram, 1024, 0)) {

     # 利用$server->peeraddr(); 取回來源udp 的ip位址,不過這裡得到的位址是個class,要經過轉換才行
     # 可以用 inet_ntoa($ipaddr) 轉成常見的IP 字串

     my $ipaddr = $server->peeraddr();
     $host = gethostbyaddr($ipaddr, AF_INET);

     # 為了避免系統資源浪費,可以讓迴圈休息一下,sleep() 函數最小休息1秒,所以要少於1秒就可以用 select 函數
     # sleep(1);
     select(undef,undef,undef,0.2);    

}

Perl 和網路有關的函數如下,截錄自 http://www.icewalkers.com/Perl/5.8.0/lib/Socket.html

inet_aton HOSTNAME

Takes a string giving the name of a host, and translates that to an opaque string (if programming in C, struct in_addr). Takes arguments of both the 'rtfm.mit.edu' type and '18.181.0.24'. If the host name cannot be resolved, returns undef. For multi-homed hosts (hosts with more than one address), the first address found is returned.

For portability do not assume that the result of inet_aton() is 32 bits wide, in other words, that it would contain only the IPv4 address in network order.

inet_ntoa IP_ADDRESS
Takes a string (an opaque string as returned by inet_aton(), or a v-string representing the four octets of the IPv4 address in network order) and translates it into a string of the form 'd.d.d.d' where the 'd's are numbers less than 256 (the normal human-readable four dotted number notation for Internet addresses).
INADDR_ANY

Note: does not return a number, but a packed string.

Returns the 4-byte wildcard ip address which specifies any of the hosts ip addresses. (A particular machine can have more than one ip address, each address corresponding to a particular network interface. This wildcard address allows you to bind to all of them simultaneously.) Normally equivalent to inet_aton('0.0.0.0').

INADDR_BROADCAST

Note: does not return a number, but a packed string.

Returns the 4-byte 'this-lan' ip broadcast address. This can be useful for some protocols to solicit information from all servers on the same LAN cable. Normally equivalent to inet_aton('255.255.255.255').

INADDR_LOOPBACK

Note - does not return a number.

Returns the 4-byte loopback address. Normally equivalent to inet_aton('localhost').

INADDR_NONE

Note - does not return a number.

Returns the 4-byte 'invalid' ip address. Normally equivalent to inet_aton('255.255.255.255').

sockaddr_family SOCKADDR
Takes a sockaddr structure (as returned by pack_sockaddr_in(), pack_sockaddr_un() or the perl builtin functions getsockname() and getpeername()) and returns the address family tag. It will match the constant AF_INET for a sockaddr_in and AF_UNIX for a sockaddr_un. It can be used to figure out what unpacker to use for a sockaddr of unknown type.
sockaddr_in PORT, ADDRESS
 
sockaddr_in SOCKADDR_IN
In a list context, unpacks its SOCKADDR_IN argument and returns an array consisting of (PORT, ADDRESS). In a scalar context, packs its (PORT, ADDRESS) arguments as a SOCKADDR_IN and returns it. If this is confusing, use pack_sockaddr_in() and unpack_sockaddr_in() explicitly.
pack_sockaddr_in PORT, IP_ADDRESS
Takes two arguments, a port number and an opaque string, IP_ADDRESS (as returned by inet_aton(), or a v-string). Returns the sockaddr_in structure with those arguments packed in with AF_INET filled in. For Internet domain sockets, this structure is normally what you need for the arguments in bind(), connect(), and send(), and is also returned by getpeername(), getsockname() and recv().
unpack_sockaddr_in SOCKADDR_IN
Takes a sockaddr_in structure (as returned by pack_sockaddr_in()) and returns an array of two elements: the port and an opaque string representing the IP address (you can use inet_ntoa() to convert the address to the four-dotted numeric format). Will croak if the structure does not have AF_INET in the right place.
sockaddr_un PATHNAME
 
sockaddr_un SOCKADDR_UN
In a list context, unpacks its SOCKADDR_UN argument and returns an array consisting of (PATHNAME). In a scalar context, packs its PATHNAME arguments as a SOCKADDR_UN and returns it. If this is confusing, use pack_sockaddr_un() and unpack_sockaddr_un() explicitly. These are only supported if your system has <sys/un.h>.
pack_sockaddr_un PATH
Takes one argument, a pathname. Returns the sockaddr_un structure with that path packed in with AF_UNIX filled in. For unix domain sockets, this structure is normally what you need for the arguments in bind(), connect(), and send(), and is also returned by getpeername(), getsockname() and recv().
unpack_sockaddr_un SOCKADDR_UN
Takes a sockaddr_un structure (as returned by pack_sockaddr_un()) and returns the pathname. Will croak if the structure does not have AF_UNIX in the right place.
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