mirror of
https://gitlab.isc.org/isc-projects/bind9.git
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145 lines
3.4 KiB
Plaintext
145 lines
3.4 KiB
Plaintext
Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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See COPYRIGHT in the source root or http://isc.org/copyright.html for terms.
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UDP receive:
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/*
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* General flow:
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*
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* If I/O result == CANCELED, free the buffer and notify everyone as
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* the various queues drain.
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*
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* If I/O is error (not canceled and not success) log it, free the buffer,
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* and restart.
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*
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* If query:
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* if no listeners: free the buffer, restart.
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* if listener: allocate event, fill in details.
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* If cannot allocate, free buffer, restart.
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* if rq event queue is not empty, queue. else, send.
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* restart.
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*
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* If response:
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* Allocate event, fill in details.
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* If cannot allocate, free buffer, restart.
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* find target. If not found, free buffer, restart.
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* if event queue is not empty, queue. else, send.
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* restart.
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*/
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UDP restart:
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/*
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* If too many recv()'s are already running, just return.
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*
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* If no one is attached to us, just return.
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*
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* Allocate a new buffer to receive into.
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* If no more buffers:
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* If there are buffers handed out: wait for one to come back.
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* If there are no buffers handed out:
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* If there are responses attached to us, just return.
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* If there are queries only, send one an error event.
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*
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*
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* start recv() on socket. If this fails:
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* Free buffer.
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* Set dispatch state to "shutting down" and why to "socket error"
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* Start failsafe shutdown.
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*/
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Adding a response:
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/*
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* If shutting down, return error.
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*
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* Allocate an unique messageid and return it. If none can be allocated,
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* return that.
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*
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* Allocate a new structure and fill it in. If no memory, return that.
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*
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* Insert into the correct linked list.
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*
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* If the receiver is not running, try to start it.
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*/
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Adding a request:
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/*
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* If shutting down, return error.
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*
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* Allocate new structure and fill it in. If no memory, return that.
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*
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* Insert it into the linked list.
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*
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* If the incoming query packet queue is not empty, pull an item off and
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* send that event to this task.
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*
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* If the receiver is not running, try to start it.
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*/
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Detaching a response:
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/*
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* decrement dispatch reference count by one. If zero, remember to kill it
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* later.
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*
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* unlink the response from the hashed list.
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*
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* Free any buffers and events attached to the response structure.
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*
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* Free the response structure.
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*
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* If an event is also being returned, jump to "internal event free" below.
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*
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* If the ref count became zero above, destroy this dispatch fully, and return.
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*
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* If the receiver is not running, try to start it.
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*/
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Detaching a request:
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/*
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* decrement dispatch ref count by one. If zero, remember to kill it later.
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*
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* unlink from the request list.
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*
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* Free the response structure.
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*
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* If an event is also being returned, jump to "internal event free" below.
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*
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* If the ref count became zero above, destroy the dispatch fully, and return.
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*
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* If the receiver is not running, try to start it.
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*/
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Internal event free (from library space):
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/*
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* If it is the failsafe event, send it to the next response/request on the
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* dispatcher, and return.
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*
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* Free buffer.
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*
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* Free event.
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*/
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Returning an event (from application space):
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/*
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* If it is the failsafe event, die.
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*
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* Free associated buffer.
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*
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* Free event.
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*
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* If response: do next response on this response's queue, if any.
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* If request: do next request on this dispatcher's queue, if any.
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*
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* If the receiver is not running, try to start it.
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*/
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