refactor: modify xdp attach code

lib/Sys/Ebpf/Link/Netlink/Constants/Rtnetlink.pm

@@ -0,0 +1,96 @@
+package Sys::Ebpf::Link::Netlink::Constants::Rtnetlink;
+
+use strict;
+use warnings;
+use utf8;
+
+use Exporter 'import';
+
+# cf. https://github.com/torvalds/linux/blob/master/include/uapi/linux/rtnetlink.h
+my %constants = (
+
+    # /* Routing table identifiers. */
+    # /* Types of messages */
+    'RTM_BASE'             => 16,
+    'RTM_NEWLINK'          => 16,
+    'RTM_DELLINK'          => 17,
+    'RTM_GETLINK'          => 18,
+    'RTM_SETLINK'          => 19,
+    'RTM_NEWADDR'          => 20,
+    'RTM_DELADDR'          => 21,
+    'RTM_GETADDR'          => 22,
+    'RTM_NEWROUTE'         => 24,
+    'RTM_DELROUTE'         => 25,
+    'RTM_GETROUTE'         => 26,
+    'RTM_NEWNEIGH'         => 28,
+    'RTM_DELNEIGH'         => 29,
+    'RTM_GETNEIGH'         => 30,
+    'RTM_NEWRULE'          => 32,
+    'RTM_DELRULE'          => 33,
+    'RTM_GETRULE'          => 34,
+    'RTM_NEWQDISC'         => 36,
+    'RTM_DELQDISC'         => 37,
+    'RTM_GETQDISC'         => 38,
+    'RTM_NEWTCLASS'        => 40,
+    'RTM_DELTCLASS'        => 41,
+    'RTM_GETTCLASS'        => 42,
+    'RTM_NEWTFILTER'       => 44,
+    'RTM_DELTFILTER'       => 45,
+    'RTM_GETTFILTER'       => 46,
+    'RTM_NEWACTION'        => 48,
+    'RTM_DELACTION'        => 49,
+    'RTM_GETACTION'        => 50,
+    'RTM_NEWPREFIX'        => 52,
+    'RTM_GETMULTICAST'     => 58,
+    'RTM_GETANYCAST'       => 62,
+    'RTM_NEWNEIGHTBL'      => 64,
+    'RTM_GETNEIGHTBL'      => 66,
+    'RTM_SETNEIGHTBL'      => 67,
+    'RTM_NEWNDUSEROPT'     => 68,
+    'RTM_NEWADDRLABEL'     => 72,
+    'RTM_DELADDRLABEL'     => 73,
+    'RTM_GETADDRLABEL'     => 74,
+    'RTM_GETDCB'           => 78,
+    'RTM_SETDCB'           => 79,
+    'RTM_NEWNETCONF'       => 80,
+    'RTM_GETNETCONF'       => 82,
+    'RTM_NEWMDB'           => 84,
+    'RTM_DELMDB'           => 85,
+    'RTM_GETMDB'           => 86,
+    'RTM_NEWNSID'          => 88,
+    'RTM_DELNSID'          => 89,
+    'RTM_GETNSID'          => 90,
+    'RTM_NEWSTATS'         => 92,
+    'RTM_GETSTATS'         => 94,
+    'RTM_NEWCACHEREPORT'   => 96,
+    'RTM_NEWCHAIN'         => 100,
+    'RTM_DELCHAIN'         => 101,
+    'RTM_GETCHAIN'         => 102,
+    'RTM_NEWNEXTHOP'       => 104,
+    'RTM_DELNEXTHOP'       => 105,
+    'RTM_GETNEXTHOP'       => 106,
+    'RTM_NEWLINKPROP'      => 108,
+    'RTM_DELLINKPROP'      => 109,
+    'RTM_GETLINKPROP'      => 110,
+    'RTM_NEWVLAN'          => 112,
+    'RTM_DELVLAN'          => 113,
+    'RTM_GETVLAN'          => 114,
+    'RTM_NEWNEXTHOPBUCKET' => 116,
+    'RTM_DELNEXTHOPBUCKET' => 117,
+    'RTM_GETNEXTHOPBUCKET' => 118,
+    'RTM_NEWTUNNEL'        => 120,
+    'RTM_DELTUNNEL'        => 121,
+    'RTM_GETTUNNEL'        => 122,
+);
+
+# Export all constants
+our @EXPORT_OK   = keys %constants;
+our %EXPORT_TAGS = ( all => \@EXPORT_OK );
+
+# Define constants as subroutines
+for my $name (@EXPORT_OK) {
+    no strict 'refs';
+    *{$name} = sub () { $constants{$name} };
+}
+
+1;

lib/Sys/Ebpf/Link/Netlink/Socket.pm

@@ -42,8 +42,8 @@ sub new {
     setsockopt( $self->{sock}, SOL_NETLINK, NETLINK_EXT_ACK, $one )
         or warn "Failed to set NETLINK_EXT_ACK: $!";
 
-    # ソケットをバインド
-    my $sockaddr_nl = pack_sockaddr_nl($$);    # プロセスのPIDにバインド
+    # ソケットをバインド(procss pid bind)
+    my $sockaddr_nl = pack_sockaddr_nl($$);
     bind( $self->{sock}, $sockaddr_nl )
         or die "Failed to bind Netlink socket: $!";
 
@@ -81,6 +81,28 @@ sub close {
     close( $self->{sock} ) if $self->{sock};
 }
 
+# helper functions
+
+sub get_error_message {
+    my ($response) = @_;
+    my $offset     = NLMSG_HDRLEN + 4;    # After error code
+    my $len        = length($response);
+
+    if ( $len > $offset ) {
+        my $attr_data = substr( $response, $offset );
+        while ( length($attr_data) >= NLA_HDRLEN ) {
+            my ( $nla_len, $nla_type ) = unpack( 'S S', $attr_data );
+            my $payload
+                = substr( $attr_data, NLA_HDRLEN, $nla_len - NLA_HDRLEN );
+            if ( $nla_type == 1 ) {    # NLMSGERR_ATTR_MSG
+                return unpack( 'Z*', $payload );
+            }
+            $attr_data = substr( $attr_data, ( $nla_len + 3 ) & ~3 );
+        }
+    }
+    return "";
+}
+
 # cf. https://github.com/torvalds/linux/blob/3efc57369a0ce8f76bf0804f7e673982384e4ac9/include/uapi/linux/netlink.h#L37
 # typedef unsigned short __kernel_sa_family_t;
 # struct sockaddr_nl {