Chapter 9
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| 9.1
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There are a number of situations where
sctp_peeloff can play an important role. An example
application that might use this function is a traditional UDP-like
server that responds to requests such as small transactions, but
occasionally is requested to do a long-term audit. In most cases,
you only need to send one or two small messages and no more; but
when a audit request arrives, a long-term conversation is invoked,
sending audit information. In this situation, you would peel off
the audit into its own thread or process to do the audit.
In summary, any application that has mainly
small requests but on occasion needs to have a long-term
conversation can take advantage of sctp_peeloff.
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| 9.2
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The server side closes automatically when the
client closes the association. This is because SCTP does not
support the half-closed state, so when the client calls close, the
shutdown sequence will flush any pending data the server had queued
for the client and complete the shutdown, closing the
association.
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| 9.3
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In the one-to-one style, a connect call must be
performed first, and so when the COOKIE is sent to the peer, no
data is pending. For the one-to-many style, an application can send
data to a peer to set up an association. This means that when the
COOKIE is sent, the DATA is available to send to the peer.
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| 9.4
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The only time a peer that you would be setting
up an association with would be able to send back data is if it had
DATA pending BEFORE the connection was set up. This would occur if
each side was using the one-to-many style and each side did a send
to implicitly set up the association. This type of association
setup is called an INIT collision, and details on it can be found
in Chapter 4 of [Stewart and Xie 2001].
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| 9.5
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In some cases, not all addresses that are bound
may be passed to a peer endpoint. In particular, when addresses
that an application has bound contain both private and public IP
addresses, only the public addresses may be shared with a peer
endpoint. Another example is found in IPv6, where link-local
addresses cannot necessarily be shared with a peer.
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