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Merge "res_fax: Fix deadlock in ast_channel_get_t38_state()."

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This commit is contained in:
Joshua Colp
2016-08-26 14:03:10 -05:00
committed by Gerrit Code Review
parent 179e8c15c8 5eb6cb969f
commit 4a8bdfc49b
2 changed files with 31 additions and 7 deletions
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6
include/asterisk/channel.h
View File

@@ -2549,7 +2549,11 @@ static inline int ast_fdisset(struct pollfd *pfds, int fd, int maximum, int *sta
return 0;
}
/*! \brief Retrieves the current T38 state of a channel */
/*!
* \brief Retrieves the current T38 state of a channel
*
* \note Absolutely _NO_ channel locks should be held before calling this function.
*/
static inline enum ast_t38_state ast_channel_get_t38_state(struct ast_channel *chan)
{
enum ast_t38_state state = T38_STATE_UNAVAILABLE;

32
res/res_fax.c
View File

@@ -3001,8 +3001,14 @@ static struct ast_frame *fax_gateway_detect_v21(struct fax_gateway *gateway, str
}
if (gateway->detected_v21) {
enum ast_t38_state state_other;
destroy_v21_sessions(gateway);
if (ast_channel_get_t38_state(other) == T38_STATE_UNKNOWN) {
ast_channel_unlock(chan);
state_other = ast_channel_get_t38_state(other);
ast_channel_lock(chan);
if (state_other == T38_STATE_UNKNOWN) {
ast_debug(1, "detected v21 preamble from %s\n", ast_channel_name(active));
return fax_gateway_request_t38(gateway, chan, f);
} else {
@@ -3043,6 +3049,7 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
struct ast_control_t38_parameters *control_params = f->data.ptr;
struct ast_channel *other = (active == chan) ? peer : chan;
struct ast_fax_session_details *details;
enum ast_t38_state state_other;
if (f->datalen != sizeof(struct ast_control_t38_parameters)) {
/* invalaid AST_CONTROL_T38_PARAMETERS frame, we can't
@@ -3065,9 +3072,11 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
}
if (control_params->request_response == AST_T38_REQUEST_NEGOTIATE) {
enum ast_t38_state state = ast_channel_get_t38_state(other);
ast_channel_unlock(chan);
state_other = ast_channel_get_t38_state(other);
ast_channel_lock(chan);
if (state == T38_STATE_UNKNOWN) {
if (state_other == T38_STATE_UNKNOWN) {
/* we detected a request to negotiate T.38 and the
* other channel appears to support T.38, we'll pass
* the request through and only step in if the other
@@ -3080,7 +3089,7 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
details->gateway_timeout = FAX_GATEWAY_TIMEOUT;
ao2_ref(details, -1);
return f;
} else if (state == T38_STATE_UNAVAILABLE || state == T38_STATE_REJECTED) {
} else if (state_other == T38_STATE_UNAVAILABLE || state_other == T38_STATE_REJECTED) {
/* the other channel does not support T.38, we need to
* step in here */
ast_debug(1, "%s is attempting to negotiate T.38 but %s does not support it\n", ast_channel_name(active), ast_channel_name(other));
@@ -3160,7 +3169,10 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
/* our request to negotiate T.38 was refused, if the other
* channel supports T.38, they might still reinvite and save
* the day. Otherwise disable the gateway. */
if (ast_channel_get_t38_state(other) == T38_STATE_UNKNOWN) {
ast_channel_unlock(chan);
state_other = ast_channel_get_t38_state(other);
ast_channel_lock(chan);
if (state_other == T38_STATE_UNKNOWN) {
gateway->t38_state = T38_STATE_UNAVAILABLE;
} else {
ast_framehook_detach(chan, details->gateway_id);
@@ -3366,8 +3378,16 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
}
if (!gateway->bridged) {
enum ast_t38_state state_chan;
enum ast_t38_state state_peer;
ast_channel_unlock(chan);
state_chan = ast_channel_get_t38_state(chan);
state_peer = ast_channel_get_t38_state(peer);
ast_channel_lock(chan);
/* 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) {
if (state_chan == T38_STATE_UNAVAILABLE && 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));
ast_framehook_detach(chan, gateway->framehook);
details->gateway_id = -1;