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Give zombies a safe channel driver to use.

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Recent crashes from zombie channels suggests that they need a safe home to
goto.  When a masquerade happens, the physical part of the zombie channel
is hungup.  The hangup normally sets the channel private pointer to NULL.
If someone then blindly does a callback to the channel driver, a crash is
likely because the private pointer is NULL.

The masquerade now sets the channel technology of zombie channels to the
kill channel driver.

Related to the following issues:
(issue #19116)
(issue #19310)

Review: https://reviewboard.asterisk.org/r/1224/


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@320796 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Richard Mudgett
2011-05-25 16:23:11 +00:00
parent 5427820aaf
commit aa64eb1077
3 changed files with 64 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
main/features.c
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@@ -469,59 +469,16 @@ struct ast_dial_features {
int is_caller;
};
#if defined(ATXFER_NULL_TECH)
static struct ast_frame *null_read(struct ast_channel *chan)
{
/* Hangup channel. */
return NULL;
}
static struct ast_frame *null_exception(struct ast_channel *chan)
{
/* Hangup channel. */
return NULL;
}
static int null_write(struct ast_channel *chan, struct ast_frame *frame)
{
/* Hangup channel. */
return -1;
}
static int null_fixup(struct ast_channel *oldchan, struct ast_channel *newchan)
{
/* No problem fixing up the channel. */
return 0;
}
static int null_hangup(struct ast_channel *chan)
{
chan->tech_pvt = NULL;
return 0;
}
static const struct ast_channel_tech null_tech = {
.type = "NULL",
.description = "NULL channel driver for atxfer",
.capabilities = -1,
.read = null_read,
.exception = null_exception,
.write = null_write,
.fixup = null_fixup,
.hangup = null_hangup,
};
#endif /* defined(ATXFER_NULL_TECH) */
#if defined(ATXFER_NULL_TECH)
/*!
* \internal
* \brief Set the channel technology to the NULL technology.
* \brief Set the channel technology to the kill technology.
*
* \param chan Channel to change technology.
*
* \return Nothing
*/
static void set_null_chan_tech(struct ast_channel *chan)
static void set_kill_chan_tech(struct ast_channel *chan)
{
int idx;
@@ -538,8 +495,8 @@ static void set_null_chan_tech(struct ast_channel *chan)
chan->tech_pvt = NULL;
}
/* Install the NULL technology and wake up anyone waiting on it. */
chan->tech = &null_tech;
/* Install the kill technology and wake up anyone waiting on it. */
chan->tech = &ast_kill_tech;
for (idx = 0; idx < AST_MAX_FDS; ++idx) {
switch (idx) {
case AST_ALERT_FD:
@@ -3115,7 +3072,7 @@ static struct ast_channel *feature_request_and_dial(struct ast_channel *caller,
* Get rid of caller's physical technology so it is free for
* other calls.
*/
set_null_chan_tech(caller);
set_kill_chan_tech(caller);
#endif /* defined(ATXFER_NULL_TECH) */
} else {
/* caller is not hungup so monitor it. */