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Add channel lock protection around translation path setup.

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Most callers of ast_channel_make_compatible() happen before the channels
enter a two party bridge.  With the new bridging framework, two party
bridging technologies may also call ast_channel_make_compatible() when
there is more than one thread involved with the two channels.

* Added channel lock protection in set_format() and
ast_channel_make_compatible_helper() when dealing with the channel's
native formats while setting up a translation path.

* Fixed best_src_fmt and best_dst_fmt usage consistency in
ast_channel_make_compatible_helper().  The call to
ast_translator_best_choice() got them backwards.

* Updated some callers of ast_channel_make_compatible() and the function
documentation.  There is actually a difference between the two channels
passed in.

* Fixed the deadlock potential in res_fax.c dealing with
ast_channel_make_compatible().  The deadlock potential was already there
anyway because res_fax called ast_channel_make_compatible() with chan
locked.

(closes issue ASTERISK-22542)
Reported by: Matt Jordan

Review: https://reviewboard.asterisk.org/r/2915/
........

Merged revisions 401239 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@401240 65c4cc65-6c06-0410-ace0-fbb531ad65f3
changes/97/197/1
Richard Mudgett 12 years ago
parent 7352433be5
commit 057d105c5a
4 changed files with 84 additions and 46 deletions
Show Stats Download Patch File Download Diff File

4
apps/app_dial.c
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@ -870,7 +870,7 @@ static void do_forward(struct chanlist *o, struct cause_args *num,
c = o->chan = ast_request(tech, ast_channel_nativeformats(in), in, stuff, &cause);
if (c) {
if (single && !caller_entertained) {
ast_channel_make_compatible(o->chan, in);
ast_channel_make_compatible(in, o->chan);
}
ast_channel_lock_both(in, o->chan);
ast_channel_inherit_variables(in, o->chan);
@ -1070,7 +1070,7 @@ static struct ast_channel *wait_for_answer(struct ast_channel *in,
ast_deactivate_generator(in);
/* If we are calling a single channel, and not providing ringback or music, */
/* then, make them compatible for in-band tone purpose */
if (ast_channel_make_compatible(outgoing->chan, in) < 0) {
if (ast_channel_make_compatible(in, outgoing->chan) < 0) {
/* If these channels can not be made compatible,
* there is no point in continuing. The bridge
* will just fail if it gets that far.

21
include/asterisk/channel.h
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@ -1984,14 +1984,23 @@ int ast_readstring_full(struct ast_channel *c, char *s, int len, int timeout, in
/*!
* \brief Makes two channel formats compatible
* \param c0 first channel to make compatible
* \param c1 other channel to make compatible
* \brief Make the frame formats of two channels compatible.
*
* \param chan First channel to make compatible. Should be the calling party.
* \param peer Other channel to make compatible. Should be the called party.
*
* \note Absolutely _NO_ channel locks should be held before calling this function.
*
* \details
* Set two channels to compatible formats -- call before ast_channel_bridge in general.
* \return Returns 0 on success and -1 if it could not be done
* Set two channels to compatible frame formats in both
* directions. The path from peer to chan is made compatible
* first to allow for in-band audio in case the other direction
* cannot be made compatible.
*
* \retval 0 on success.
* \retval -1 on error.
*/
int ast_channel_make_compatible(struct ast_channel *c0, struct ast_channel *c1);
int ast_channel_make_compatible(struct ast_channel *chan, struct ast_channel *peer);
/*!
* \brief Bridge two channels together (early)

97
main/channel.c
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@ -5288,11 +5288,10 @@ static int set_format(struct ast_channel *chan,
const int direction)
{
struct ast_trans_pvt *trans_pvt;
struct ast_format_cap *cap_native = ast_channel_nativeformats(chan);
struct ast_format_cap *cap_native;
struct ast_format best_set_fmt;
struct ast_format best_native_fmt;
int res;
char from[200], to[200];
ast_best_codec(cap_set, &best_set_fmt);
@ -5324,6 +5323,9 @@ static int set_format(struct ast_channel *chan,
return 0;
}
ast_channel_lock(chan);
cap_native = ast_channel_nativeformats(chan);
/* Find a translation path from the native format to one of the desired formats */
if (!direction) {
/* reading */
@ -5332,17 +5334,20 @@ static int set_format(struct ast_channel *chan,
/* writing */
res = ast_translator_best_choice(cap_native, cap_set, &best_native_fmt, &best_set_fmt);
}
if (res < 0) {
char from[200];
char to[200];
ast_getformatname_multiple(from, sizeof(from), cap_native);
ast_channel_unlock(chan);
ast_getformatname_multiple(to, sizeof(to), cap_set);
ast_log(LOG_WARNING, "Unable to find a codec translation path from %s to %s\n",
ast_getformatname_multiple(from, sizeof(from), cap_native),
ast_getformatname_multiple(to, sizeof(to), cap_set));
from, to);
return -1;
}
/* Now we have a good choice for both. */
ast_channel_lock(chan);
if ((ast_format_cmp(rawformat, &best_native_fmt) != AST_FORMAT_CMP_NOT_EQUAL) &&
(ast_format_cmp(format, &best_set_fmt) != AST_FORMAT_CMP_NOT_EQUAL) &&
((ast_format_cmp(rawformat, format) != AST_FORMAT_CMP_NOT_EQUAL) || trans->get(chan))) {
@ -6144,24 +6149,41 @@ int ast_channel_sendurl(struct ast_channel *chan, const char *url)
/*! \brief Set up translation from one channel to another */
static int ast_channel_make_compatible_helper(struct ast_channel *from, struct ast_channel *to)
{
struct ast_format_cap *src_cap = ast_channel_nativeformats(from); /* shallow copy, do not destroy */
struct ast_format_cap *dst_cap = ast_channel_nativeformats(to); /* shallow copy, do not destroy */
struct ast_format_cap *src_cap;
struct ast_format_cap *dst_cap;
struct ast_format best_src_fmt;
struct ast_format best_dst_fmt;
int use_slin;
int no_path;
ast_channel_lock_both(from, to);
if ((ast_format_cmp(ast_channel_readformat(from), ast_channel_writeformat(to)) != AST_FORMAT_CMP_NOT_EQUAL) &&
(ast_format_cmp(ast_channel_readformat(to), ast_channel_writeformat(from)) != AST_FORMAT_CMP_NOT_EQUAL)) {
/* Already compatible! Moving on ... */
ast_channel_unlock(to);
ast_channel_unlock(from);
return 0;
}
src_cap = ast_channel_nativeformats(from); /* shallow copy, do not destroy */
dst_cap = ast_channel_nativeformats(to); /* shallow copy, do not destroy */
/* If there's no audio in this call, don't bother with trying to find a translation path */
if (!ast_format_cap_has_type(src_cap, AST_FORMAT_TYPE_AUDIO) || !ast_format_cap_has_type(dst_cap, AST_FORMAT_TYPE_AUDIO))
if (!ast_format_cap_has_type(src_cap, AST_FORMAT_TYPE_AUDIO)
|| !ast_format_cap_has_type(dst_cap, AST_FORMAT_TYPE_AUDIO)) {
ast_channel_unlock(to);
ast_channel_unlock(from);
return 0;
}
no_path = ast_translator_best_choice(dst_cap, src_cap, &best_dst_fmt, &best_src_fmt);
if (ast_translator_best_choice(dst_cap, src_cap, &best_src_fmt, &best_dst_fmt) < 0) {
ast_log(LOG_WARNING, "No path to translate from %s to %s\n", ast_channel_name(from), ast_channel_name(to));
ast_channel_unlock(to);
ast_channel_unlock(from);
if (no_path) {
ast_log(LOG_WARNING, "No path to translate from %s to %s\n",
ast_channel_name(from), ast_channel_name(to));
return -1;
}
@ -6171,24 +6193,28 @@ static int ast_channel_make_compatible_helper(struct ast_channel *from, struct a
* no direct conversion available. If generic PLC is
* desired, then transcoding via SLINEAR is a requirement
*/
use_slin = ast_format_is_slinear(&best_src_fmt) || ast_format_is_slinear(&best_dst_fmt) ? 1 : 0;
if ((ast_format_cmp(&best_src_fmt, &best_dst_fmt) == AST_FORMAT_CMP_NOT_EQUAL) &&
(ast_opt_generic_plc || ast_opt_transcode_via_slin) &&
(ast_translate_path_steps(&best_dst_fmt, &best_src_fmt) != 1 || use_slin)) {
if (ast_format_cmp(&best_dst_fmt, &best_src_fmt) == AST_FORMAT_CMP_NOT_EQUAL
&& (ast_opt_generic_plc || ast_opt_transcode_via_slin)) {
int use_slin = (ast_format_is_slinear(&best_src_fmt)
|| ast_format_is_slinear(&best_dst_fmt)) ? 1 : 0;
int best_sample_rate = ast_format_rate(&best_src_fmt) > ast_format_rate(&best_dst_fmt) ?
ast_format_rate(&best_src_fmt) : ast_format_rate(&best_dst_fmt);
if (use_slin || ast_translate_path_steps(&best_dst_fmt, &best_src_fmt) != 1) {
int best_sample_rate = (ast_format_rate(&best_src_fmt) > ast_format_rate(&best_dst_fmt)) ?
ast_format_rate(&best_src_fmt) : ast_format_rate(&best_dst_fmt);
/* pick the best signed linear format based upon what preserves the sample rate the best. */
ast_format_set(&best_dst_fmt, ast_format_slin_by_rate(best_sample_rate), 0);
/* pick the best signed linear format based upon what preserves the sample rate the best. */
ast_format_set(&best_src_fmt, ast_format_slin_by_rate(best_sample_rate), 0);
}
}
if (ast_set_read_format(from, &best_dst_fmt) < 0) {
ast_log(LOG_WARNING, "Unable to set read format on channel %s to %s\n", ast_channel_name(from), ast_getformatname(&best_dst_fmt));
if (ast_set_read_format(from, &best_src_fmt)) {
ast_log(LOG_WARNING, "Unable to set read format on channel %s to %s\n",
ast_channel_name(from), ast_getformatname(&best_src_fmt));
return -1;
}
if (ast_set_write_format(to, &best_dst_fmt) < 0) {
ast_log(LOG_WARNING, "Unable to set write format on channel %s to %s\n", ast_channel_name(to), ast_getformatname(&best_dst_fmt));
if (ast_set_write_format(to, &best_src_fmt)) {
ast_log(LOG_WARNING, "Unable to set write format on channel %s to %s\n",
ast_channel_name(to), ast_getformatname(&best_src_fmt));
return -1;
}
return 0;
@ -6196,19 +6222,20 @@ static int ast_channel_make_compatible_helper(struct ast_channel *from, struct a
int ast_channel_make_compatible(struct ast_channel *chan, struct ast_channel *peer)
{
/* Some callers do not check return code, and we must try to set all call legs correctly */
int rc = 0;
/*
* Set up translation from the peer to the chan first in case we
* need to hear any in-band tones and the other direction fails.
*/
if (ast_channel_make_compatible_helper(peer, chan)) {
return -1;
}
/* Set up translation from the chan to the peer */
rc = ast_channel_make_compatible_helper(chan, peer);
if (rc < 0)
return rc;
/* Set up translation from the peer to the chan */
rc = ast_channel_make_compatible_helper(peer, chan);
if (ast_channel_make_compatible_helper(chan, peer)) {
return -1;
}
return rc;
return 0;
}
int ast_channel_masquerade(struct ast_channel *original, struct ast_channel *clonechan)

8
res/res_fax.c
Unescape View File

@ -3057,12 +3057,12 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
ast_channel_unlock(chan);
peer = ast_channel_bridge_peer(chan);
ast_channel_lock(chan);
if (peer) {
ast_set_read_format(peer, &gateway->peer_read_format);
ast_set_read_format(peer, &gateway->peer_write_format);
ast_channel_make_compatible(chan, peer);
}
ast_channel_lock(chan);
}
return NULL;
}
@ -3084,7 +3084,7 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
return f;
}
if (!gateway->bridged && peer) {
if (!gateway->bridged) {
/* don't start a gateway if neither channel can handle T.38 */
if (ast_channel_get_t38_state(chan) == T38_STATE_UNAVAILABLE && ast_channel_get_t38_state(peer) == T38_STATE_UNAVAILABLE) {
ast_debug(1, "not starting gateway for %s and %s; neither channel supports T.38\n", ast_channel_name(chan), ast_channel_name(peer));
@ -3113,10 +3113,12 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
ast_set_read_format_by_id(chan, AST_FORMAT_SLINEAR);
ast_set_write_format_by_id(chan, AST_FORMAT_SLINEAR);
ast_channel_unlock(chan);
ast_set_read_format_by_id(peer, AST_FORMAT_SLINEAR);
ast_set_write_format_by_id(peer, AST_FORMAT_SLINEAR);
ast_channel_make_compatible(chan, peer);
ast_channel_lock(chan);
gateway->bridged = 1;
}
@ -3381,10 +3383,10 @@ static struct ast_frame *fax_detect_framehook(struct ast_channel *chan, struct a
ast_set_read_format(chan, &faxdetect->orig_format);
ast_channel_unlock(chan);
peer = ast_channel_bridge_peer(chan);
ast_channel_lock(chan);
if (peer) {
ast_channel_make_compatible(chan, peer);
}
ast_channel_lock(chan);
return NULL;
case AST_FRAMEHOOK_EVENT_READ:
if (f) {

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