I am writing a Perl program that sends and receives messages from two sockets and acta as a switch. I have to modify the received messages received from one socket, prepend 3 bytes to the data, and finally send the modified messages to another socket. I adopt select()...sysread()...syswrite() mechanism to poll for messages between sockets. The received messages are stored in $buffer during modification.
Now I can use following way to get the received messages:
my $hexmsg = unpack("H*", $buffer);
my @msg = ( $hexmsg =~ m/../g );

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then I can insert 3 bytes to @msg using splice(). However, I don't know how to pack the message in @msg into a scalar(such as $buffer) and send it to another socket by syswrite().
I know this method is fool and I believe there must be more clever ways. Can anybody help me with this problem? Thank you in advance!
BTW, are messages in $buffer binary?

In reply to How can I modify received socket messages in Perl? by bonny95

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