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54faf09da6
An invocation of ares_cancel() walks through the request list, calling the callbacks of all pending requests on a channel. Previously, if such a callback added a new request to the channel, the request list might not end up empty, causing an abort by assertion failure. The present commit ensures that precisely all requests present upon entry of ares_cancel() are cancelled, and that adding new requests through callbacks is safe.
64 lines
2.2 KiB
C
64 lines
2.2 KiB
C
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/* Copyright (C) 2004 by Daniel Stenberg et al
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose and without fee is hereby granted, provided
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* that the above copyright notice appear in all copies and that both that
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* copyright notice and this permission notice appear in supporting
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* documentation, and that the name of M.I.T. not be used in advertising or
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* publicity pertaining to distribution of the software without specific,
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* written prior permission. M.I.T. makes no representations about the
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* suitability of this software for any purpose. It is provided "as is"
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* without express or implied warranty.
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*/
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#include "ares_setup.h"
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#include <assert.h>
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#include "ares.h"
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#include "ares_private.h"
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/*
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* ares_cancel() cancels all ongoing requests/resolves that might be going on
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* on the given channel. It does NOT kill the channel, use ares_destroy() for
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* that.
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*/
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void ares_cancel(ares_channel channel)
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{
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struct query *query;
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struct list_node list_head_copy;
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struct list_node* list_head;
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struct list_node* list_node;
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int i;
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if (!ares__is_list_empty(&(channel->all_queries)))
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{
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/* Swap list heads, so that only those queries which were present on entry
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* into this function are cancelled. New queries added by callbacks of
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* queries being cancelled will not be cancelled themselves.
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*/
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list_head = &(channel->all_queries);
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list_head_copy.prev = list_head->prev;
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list_head_copy.next = list_head->next;
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list_head_copy.prev->next = &list_head_copy;
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list_head_copy.next->prev = &list_head_copy;
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list_head->prev = list_head;
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list_head->next = list_head;
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for (list_node = list_head_copy.next; list_node != &list_head_copy; )
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{
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query = list_node->data;
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list_node = list_node->next; /* since we're deleting the query */
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query->callback(query->arg, ARES_ECANCELLED, 0, NULL, 0);
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ares__free_query(query);
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}
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}
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if (!(channel->flags & ARES_FLAG_STAYOPEN) && ares__is_list_empty(&(channel->all_queries)))
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{
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if (channel->servers)
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{
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for (i = 0; i < channel->nservers; i++)
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ares__close_sockets(channel, &channel->servers[i]);
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}
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}
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}
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