Subject: Re: Linux ip codeReply-to: (fwd)
To: None <ghudson@MIT.EDU>
From: Charles M. Hannum <email@example.com>
Date: 05/06/1995 03:50:33
22.214.171.124 ICMP Messages
UDP MUST pass to the application layer all ICMP error
messages that it receives from the IP layer. Conceptually
at least, this may be accomplished with an upcall to the
ERROR_REPORT routine (see Section 126.96.36.199).
Note that ICMP error messages resulting from sending a
UDP datagram are received asynchronously. A UDP-based
application that wants to receive ICMP error messages
is responsible for maintaining the state necessary to
demultiplex these messages when they arrive; for
example, the application may keep a pending receive
operation for this purpose.
The last part of that indicates that the application may be required
to take some explicit action to received ICMP messages. In BSD, this
action is simply using the connect() call.